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15th Symposium on Thermal Science and Engineering of Serbia

under title:

“Energy – Ecology –Efficiency”

is organized by:

University of Niš, Faculty of Mechanical Engineering Niš and

Society of Thermal Engineers of Serbia

Under patronage of the

GOVERNMENT OF THE REPUBLIC OF SERBIA MINISTRY OF EDUCATION AND SCIENCE

and supported by:

General Sponsor

SERBIAN CHAMBER OF ENGINEERS, Belgrade

Grand Donor

ENERGOPROJEKT ENTEL, Belgrade

Sponsors and Donors

VIA OCEL, Belgrade

RADIJATOR INŽENJERING, Kraljevo

VERSO IL PARADISO, Leskovac

TROX, Belgrade

GASTEH, Inđija

HERZ, Belgrade

RADING, Kraljevo

REHAU, Belgrade

WILO, Belgrade

ALFA CLIMA, Knjaževac

LABORATORIJA TESTO, Belgrade

KNAUF INSULATION Belgrade

Влада Републике Србије Министарство просвете и науке

Инжењерска комора Србије

ENERGOPROJEKT ENTEL

v

International Scientific Committee Prof. Dr Gligor Kanevče [MKD]

Prof. Dr Petar Novak [SVN] Prof. Dr Jordan Hristov [BGR]

Prof. Dr Neven Duić [HRV] Prof. Dr Engin Ture [TUR]

Prof. Dr Dušan Golubović [BIH] Prof. Dr Petar Gvero [BIH]

Dr Maria Ichim [ROU] Dr Vesna Barišić [FIN]

Prof. Dr Agis M. Papadopoulos [GRC] Prof. Dr Nenad Kažić [MNE]

Program Committee Prof. Dr Milan Radovanović, Faculty of Mechanical Engineering Belgrade

Prof. Dr Simeon Oka, Vinča Institute, Belgrade Prof. Dr Miroljub Adžić, Faculty of Mechanical Engineering Belgrade

Prof. Dr Miloš Banjac, Faculty of Mechanical Engineering Belgrade Prof. Dr Dragoslava Stojiljković, Faculty of Mechanical Engineering Belgrade

Prof. Dr Goran Jankes, Faculty of Mechanical Engineering Belgrade Dr Predrag Stefanović, Vinča Institute, Belgrade

Prof. Dr Dragoslav Šumarac, Faculty of Civil Engineering Belgrade Dr Miodrag Mesarović, Energoprojekt ENTEL, Belgrade

Prof. Dr Dušan Gvozdenac, Faculty of Technical Sciences Novi Sad Prof. Dr Milun Babić, Faculty of Mechanical Engineering Kragujevac

Prof. Dr Vladan Karamarković, Faculty of Mechanical Engineering Kraljevo Dr Žarko Stevanović, Vinča Institute, Belgrade

Prof. Dr Gradimir Ilić, Faculty of Mechanical Engineering Niš Prof. Dr Bratislav Blagojević, Faculty of Mechanical Engineering Niš Prof. Dr Dragoljub Živković, Faculty of Mechanical Engineering Niš

Honorary Committee Prof. Dr Vlastimir Nikolić, Faculty of Mechanical Engineering Niš

Prof. Dr Kosta Maglić, Vinča Institute, Belgrade Prof. Dr Dimitrije Voronjec, Faculty of Mechanical Engineering Belgrade Prof. Dr Slobodan Laković, Faculty of Mechanical Engineering Niš

Prof. Dr Nenad Radojković, Faculty of Mechanical Engineering Niš Prof. Dr Zoran Boričić, Faculty of Mechanical Engineering Niš

Prof. Dr Maja Đurović Petrović, European University, Belgrade Jaroslav Urošević, Energoprojekt ENTEL

Organizing Committee President: Prof. Dr Mladen Stojiljković, Faculty of Mechanical Engineering Niš

Vice President: Doc. Dr Mirjana Laković, Faculty of Mechanical Engineering Niš Vice President: Doc. Dr Dejan Mitrović, Faculty of Mechanical Engineering Niš

Prof. Dr Branislav Stojanović, Faculty of Mechanical Engineering Niš Prof. Dr Mića Vukić, Faculty of Mechanical Engineering Niš

Doc. Dr Jelena Janevski, Faculty of Mechanical Engineering Niš Prof. Dr Velimir Strefanović, Faculty of Mechanical Engineering Niš Doc. Dr Gordana Stefanović, Faculty of Mechanical Engineering Niš

Mr Goran Vučković, Faculty of Mechanical Engineering Niš Dr Predrag Zivković, Faculty of Mechanical Engineering Niš

Mr Dragan Kuštrimović, Faculty of Mechanical Engineering Niš Mirko Stojiljković, Faculty of Mechanical Engineering Niš Marko Ignjatović, Faculty of Mechanical Engineering Niš

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Disclaimer

The contents of the papers presented in this publication are the sole responsibility of their authors and can in no way be taken to reflect the views of the Organizer.

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Contents

1. Plenary Session 1

1.01. INTEGRATED RENEWABLE ENERGY SYSTEMS IN BUILDINGS: POTENTIAL AND PERSPECTIVES OF LOW TEMPERATURE SYSTEMS

Agis M. Papadopoulos 2

1.02. DEVELOPMENT OF THE MACEDONIAN ENERGY SECTOR IN THE FRAMEWORK OF THE ENERGY COMMUNITY

G. H. Kanevce, L. P. Kanevce 3

1.03. EXERGY ANALYSIS OF TWO-STAGE WATER TO WATER HEAT PUMP D. Antonijević, N. Rudonja, M. Komatina, D. Manić, S. Uzelac 4

1.04. EDUCATION, SCIENCE AND TECHNOLOGY – TRENDS AND ACCIVEMENTS Vojin Grković 5

1.05. NEW ENERGY TECHNOLOGIES AS A CHALLENGE FOR THERMAL ENGINEERS Miodrag Mesarović 6

2. Environmental Protection 7

2.01. POLLUTANTS DISPERSION MODELING USING CLASSICAL AND MODIFIED GAUSSIAN MODELS

Igor B. Andreevski, Gligor H. Kanevče, Ljubica P. Kanevče, Aleksandar P. Markoski, Sevde K. Stavreva 8

2.02. THE CONCEPT OF CCS READY PLANTS Sanja B. Petrović Bećirović, Đorđina Lj. Milovanović 9

2.03. A METHOD FOR DEFINING STREETS AS SOURCES OF CO2 EMISSION AND THEIR CLASSIFICATION IN THE CITY OF NIŠ

Mladen Tomić, Predrag Živković, Gradimir Ilić, Mića Vukić, Jelena Milisavljević, Petar Đekić 10

2.04. TRAFFIC AND POLLUTION IN THE CITY OF NIŠ Predrag M. Živković, Mladen A. Tomić, Gradimir S. Ilić 11

2.05. INFLUENCE OF TRAFFIC ON THE CITY OF NIŠ AIR QUALITY Predrag M. Živković, Mladen A. Tomić, Gradimir S. Ilić 12

2.06. GASIFICATION PROCESSES OF THT ORGANIC WASTE WITH PRODUTION OF THE ELECTRICAL ENERGY

Ranko Zrilic 13

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2.07. ENVIRONMENTAL BENEFITS OF USING MUNICIPAL SOLID WASTE AS AN ENERGY SOURCE-CASE STUDY: SERBIA

Dušan Marković , Gordana Stefanović , Mladen Tomić, Goran Vučković, Biljana Milutinović 14

3. Mathematical Modeling and Numerical Simulation 15

3.01. NUMERICAL PREDICTION OF OVERFIRE AIR INFLUENCE ON FEGT AND NOX EMISSION IN 350 MWe PULVERIZED COAL UTILITY BOILER

V. B. Beljanski, I. D. Tomanović, S. V. Belošević, M. A. Sijerčić, B. D. Stanković, N. Đ. Crnomarković, A. D. Stojanović 16

3.02. REVIEW OF SOFTWARE FOR SIMULATION AND OPTIMIZATION OF ENERGY SYSTEMS

Marko M. Mančić, Dragoljub S. Živković, Velimir P. Stefanović, Milan Lj. Đorđević, Saša R. Pavlović 17

3.03. MODELING OF SMALL SCALE POLYGENERATION SYSTEMS Marko M. Mančić, Dragoljub S. Živković, Velimir.P. Stefanović, Saša R. Pavlović 18

3.04. MODELING OF FLUE GAS TEMPERATURE INFLUENCE ON POLLUTANT PRODUCTS EMISSION DURING THE BIOMASS COMBUSTION

B. S. Repić, A. D. Marinković, G. S. Živković, S. Dj. Nemoda, B. D. Grubor 19

3.05. MATHEMATICAL SIMULATION AND OPTIMIZATION OF AUTONOMOUS SOLAR-WIND ENERGY INSTALLATIONS

O. S. Popel, S. E. Frid, A. V. Mordynsky 20

3.06. COMPARISON OF DIFFERENT INDIVIDUAL SOLAR WATER HEATER TYPES EFFECTIVENESS FOR CLIMATIC CONDITIONS OF RUSSIAN REGIONS

S. E. Frid, Yu. G. Kolomiets, E. V. Sushnikova 21

3.07. SOLVING THE PROBLEMS OF HIBRID AUTONOMOUS POWER-GENERATING UNIT OPTIMIZATION

I. L. Maikov, L. B. Director 22

3.08. USAGE OF METHODS OF OPTIMIZATION FOR SELECTION OF CONSTRUCTIVE CONCEPTION OF FACILITIES OF SMALL HYDRO POWER PLANTS ON PREVIOUSLY SELECTED MACRO LOCATIONS BY METHOD OF MULTY CRITERIA RANKING

Zdravko N. Milovanović, Darko Knežević, Aleksandar Milašinović, Svetlana Dumonjić-Milovanović, Jovan Škundrić 23

3.09. MODELING OF POLLUTANTS AT THE LANDFILL WASTE Sonja Stefanov, Rade Biočanin 24

3.10. CALCULATION OF FAN OPERATING PARAMETERS FOR DIFFERENT NUMBERS OF REVOLUTIONS, CONSIDERING THE INFLUENCE OF REYNOLDS NUMBER

B. P. Bogdanović, J. B. Bogdanović-Jovanović, S. Milanović 25

3.11. MONTE CARLO RANDOM WALK METHOD FOR SOLVING LAPLACE EQUATION Mladen Tomić, Predrag Živković, Mića Vukić, Gradimir Ilić, Žarko Stevanović 26

3.12. RESIDENTIAL BUILDINGS’ SUSTAINABILITY BY NON-LINEAR NORMALIZATION B. Vučićević, M. Stojiljković, N. Afgan, V. Turanjanin, M. Jovanović 27

3.13. ABOVE GROUND PIPING UNDER THE INFLUENCE OF RADIATION Marko N. Ilic, Velimir P. Stefanovic, Gradimir S. Ilic, Saša R. Pavlović 28

3.14. MATHEMATICAL MODEL AND NUMERICAL SIMULATION OF CPC-2V CONCENTRATING COLAR COLLECTOR

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Velimir P. Stefanović, Saša R. Pavlović, Marko V. Mančić, Andrijana D. Stojanović, Milan Lj. Đorđević, Žarko Janković 29

3.15. STABILITY ANALYSES OF A GUYED MAST EXPOSED TO DYNAMIC WIND ACTION M. Pezo, V. Bakić, Z. Marković, Ž. Stevanović 30

3.16. DYNAMICAL ANALYSIS OF COMBINED WIND-PHOTOVOLTAIC ENERGY SYSTEM V. Bakić, M. Pezo, M. Zivković 31

3.17. OPTIMIZATION OF OPERATION OF ENERGY SUPPLY SYSTEMS WITH COGENERATION AND ABSORPTION REFRIGERATION

Mirko M. Stojiljković, Mladen M. Stojiljković, Bratislav D. Blagojević 32

4. New and Renewable Energy Sources 33

4.01. RENEWABLE ENERGY SOURCES IN RUSSIA: PROBLEMS AND PROSPECTS OF WIDE UTILIZATION

O.S. Popel, V.E. Fortov 34

4.02. MODERN TECHNOLOGY FOR SUSTAINABLE EXPLOITATION OF GEOTHERMAL ENERGY Dragoljub S. Živković, Dragan S. Milčić, Dejan M. Mitrović, Marko V. Mančić 35

4.03. THE POSSIBILITY ADVANTAGE OF GEOTHERMAL WATERS OF SIJARINSKA SPA Dragan T. Stojiljković, Nebojša Č. Mitić, Andrija Šmelcerović 36

4.04. GEOTHERMAL ENERGY IN VOJVODINA - POTENTIAL, UTILIZATION, POSSIBILITIES AND LEGAL REGULATIONS

Milovan M. Medojević, Milana S. Perić 37

4.05. POSSIBILITIES FOR USING VINEYARD PRUNNING BIOMASS IN SERBIA

Ivana Radojević, Gordana Stefanović, Marko V. Mančić, Dušan Marković, Zorica Ranković Vasić 38

4.06. SMALL SCALE PLANT FOR COMBINED HEAT AND POWER GENERATION UTILIZING LOCAL BIOMASS

B. S. Repić, D. V. Dakić, D. M. Đurović, A. M. Erić, M. J. Paprika 39

4.07. MODELING OF TRANSPORT PHENOMENA DURING BALED SOYBEAN RESIDUES COMBUSTION

Aleksandar M. Erić, Dragoljub V. Dakić, Mirko S. Komatina, Stevan Đ. Nemoda, Branislav S. Repić Milica. R. Mladenović 40

4.08. SOLAR ORGANIC RANKINE CYCLES Milan. Lj. Đorđević, Velimir P. Stefanović, Marko V. Mančić, Saša R. Pavlović, Žarko Janković 41

4.09. ELECTRIC ENERGY GENERATION AND CO2 EMISSIONS BY PV SYSTEMS Jasna Radulović, Dragan Taranović, Mirko Blagojević, Jasmina Skerlić, Milorad Bojić 42

4.10. APPLICATION OF SOLAR ENERGY IN STREET LIGHTING DESIGNING Kristina Zubović 43

4.11. WIND ENERGY POTENTIALS ON STARA PLANINA MOUNTAIN

Predrag M. Živković, Dušan LJ. Petković, Mladen A. Tomić, Gradimir S. Ilić, Žarko M. Stevanović, Andrijana D. Stojanović 44

4.12. WOOD CHIPS PRODUCTION - LOCATIONS AND WOOD CHIP PRODUCTION EQUIPMENT Dejan Mitrović, Branislav Stojanović, Mladen Stojiljković, Jelena Janevski, Marko Ignjatović 45

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4.13. THE SUPPLY OF HEAT ENERGY FOR SMALLER URBAN UNITS OBTAINED FROM RENEWABLE ENERGY SOURCES

Maja N. Marković; Ana A. Berket Bakota; Milena S. Jovanović; Branislav V. Stojanović; Jelena N. Janevski 46

4.14. BIOMASS DISTRICT HEATING SYSTEMS AND CONTROL STRATEGIES Marko G. Ignjatović, Bratislav D. Blagojević, Dejan M. Mitrović, Mirko M. Stojiljković 47

4.15. POSSIBILITIES OF USING BIOMASS IN THE SLAUGHTER-HOUSE INDUSTRY FOR HEAT PRODUCTION

D. V. Dakić, B. S. Repić, A. M. Erić, D. M. Đurović, M. R. Mladenović 48

4.16. IMPACT OF THE NUMBER AND OF THE TYPES OF THE COVERS ON THE TOP HEAT LOSS OF A SOLAR WATER HEATER FLAT PLATE COLLECTOR

Velimir P. Stefanović, Andrijana D. Stojanović, Saša R. Pavlović, Predrag Živković 49

4.17. POTENTIAL OF MUNICIPAL SOLID WASTE AS RENEWABLE ENERGY SOURCE: CURRENT STATE IN SERBIA AND THE WORLD


4.18. ADVANTAGES AND DISADVANTAGES OF INNOVATIVE TECHNOLOGIES FOR THERMAL TREATMENT OF MUNICIPAL SOLID WASTE


4.19. MULTI-CRITERIA METHODS FOR RANKING POLYGENERATION SYSTEMS BASED ON RENEWABLE ENERGY SOURCES

S. M. Savić, G. Lj. Janaćković, M. S. Stanković 52

4.20. EFFICIENT USE OF WIND ENERGY USING WIND TURBINES WITH CVT DRIVE TRAIN Vukašin Pavlović, Miloš Miloševic, Nenad D. Pavlović, Milan Pavlović, Nataša Jovanović 53

4.21. PRODUCTION OF PELLETS AND THEIR USE FOR HEATING PURPOSES Mladen Stojiljković, Mirjana Laković, Branislav Stojanović, Jelena Janevski, Dejan Mitrović 54

4.22. THE USE OF AQUIFERS AS SEASONAL THERMAL STORAGE RESERVOIRS Miloš Banjac, Mirjana Laković 55

4.23. POTENTIALS AND POSSIBILITIES OF USING WOOD BIOMASS IN SERBIA Jelena N. Janevski, Branislav V. Stojanović, Mirjana S. Laković, Mirko M. Stojiljković 56

5. Fluid Flow and Heat and Mass Transfer 57

5.01. THERMOECONOMIC MODELING OF A SIMPLE HEAT PUMP CYCLE: AN ALTERNATIVE APPROACH FOR VALVE ISOLATION

A. B. Lourenço, J. J. Santos, J. L. Donatelli 58

5.02. THERMAL BIOMASS CONVERSION INTO SYNGAS V. V. Kosov , V. A. Sinelshchikov, V. M. Zaichenko 59

5.03. ONE DIMENSIONAL MODEL OF COOLING WATER IN COUNTERFLOW COOLING TOWER Dušan Golubović, Dušica Golubović 60

5.04. INFLUENCE OF VOLUME INITIALIZATION IN LARGE EDDY SIMULATION OF TURBULENT COMBUSTION INSIDE CLOSED VESSEL

L. Perković, M. Tomić, N. Duić 61

5.05. THERMAL INSTABILITY IN PERTURBED POISEUILLE FLOW IN PRESENCE OF TIME VARYING TEMPERATURE DIFFERENCE BETWEEN THE WALLS

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Milos M. Jovanovic, Jelena D. Nikodijevic 62

5.06. CHARACTERISTICS OF COMBUSTION CHAMBER FOR COMBUSTION OF PELLETS AND WOODCHIPS

Branislav Stojanović, Jelena Janevski, Mladen Stojiljković, Dejan Mitrović 63

5.07. VERTICAL TEMPERATURE PROFILE IN THE INSTALLATION FOR THE COMBUSTION OF WASTE FUELS IN THE FLUIDIZED BED FURNACE

Milica R. Mladenović, Dragoljub V.Dakić, Stevan Đ. Nemoda, Rastko V. Mladenović, Aleksandar M. Erić, Milijana Paprika, Mirko S. Komatina 64

5.08. INFLUENCE OF THE ALTITUDE ON EVAPORATION RATE OF COOLING WATER AT NATURAL DRAUGHT COOLING TOWER

Vladimir I. Mijakovski, Vangelče B. Mitrevski, Nikola I. Mijakovski 65

5.09. MHD DYNAMIC AND DIFFUSION BOUNDARY LAYER FLOW OF VARIABLE ELECTRICAL CONDUCTIVITY FLUID PAST A CIRCULAR CILYNDER

A. Boričić, Ž. Stamenković, B. Boričić 66

6. Examination of Operating Plants and Experimental Examination of Plants 67

6.01. POSSIBILITY OF IMPROVING MAINTENANCE PROCESS IN HEATING PLANTS Peđa Milosavljević, Dragoljub Živković, Dragan Milčić 68

6.02. EXPERIMENTAL DETERMINATION AND COMPARISON OF HEAT PERFORMANCES OF THREE FLAT COLLECTORS AND A CPC-2V CONCENTRATING COLLECTOR WITH A SMALL CONCENTRATION RATIO

Velimir P. Stefanović, Saša R. Pavlović, Andrijana D. Stojanović, Marko V. Mančić, Milan Lj. Đorđević 69

6.03. EFFECT OF CARBON DIOXIDE CONTENT IN NATURAL GAS ON EMISSIONS AT LEAN PREMIXED CONDITIONS

Marija Živković, Miroljub Adžić, Aleksandar Milivojević, Vuk Adžić, Vasko Fotev 70

6.04. THE IMPACT OF LOAD OF TRANSMISSION LINES AND TRANSFORMERS ON POWER SYSTEM GENERATION

Ljiljana M. Samardžić, Vladan D. Krsman 71

6.05. THE INFORMATION SYSTEM OF REPORTING AND MONITORING PROCESSES IN A POWER PLANT HEATING PLANT NOVI SAD

Slobodan Stevanović, Sladjana Barjaktarović, Nebojša Kaljević, Tatjana Karadjinović, 72

6.06. PARTICULATE MATTER EMISSION INVESTIGATION ON THE UPGRADED ELECROSTATIC PRECIPITATORS AT TPP ''NIKOLA TESLA''

Milić Erić, Predrag Škobalj, Zoran Marković, Dejan Cvetinović, Rastko Jovanović, Predrag Stefanović 73

6.07. MATHEMATICAL MODELLING AND EXPERIMENTAL INVESTIGATION OF THE FURNACE FOR STRAW COMBUSTION

D. Djurovic, S. Nemoda, D. Dakic, A. Eric, B. Repic 74

6.08. VARIATION OF OPERATION OF LOW-PRESSURE REVERSIBLE AXIAL FAN DRIVEN BY INDUCTION MOTOR FROM START TO THE STEADY-STATE

Živan Spasić, Božidar Bogdanović, Milan Radić 75

7. Energy Efficiency and Rational Energy Management 76

7.01. ENERGY EFFICIENCY OF TYPICAL SERBIAN RURAL HOUSES

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D. M. Šumarac, M.N. Todorović, Z.B. Perović, R. D. Roglić 77

7.02. THE DIFFERENT ENERGY SOURCE TYPE INFLUENCE ON BUILDING PRIMARY ENERGY NEEDS M. N. Todorović, T. S. Bajc 78

7.03. A REVIEW OF BENCHMARKING AND RATING CONCEPTS WITHIN THE FRAMEWORK OF BUILDING ENERGY CERTIFICATION SCHEMES

J. Skerlić, D. Gordić 79

7.04. FORECASTING ENERGY CONSUMPTION IN RESIDENTIAL HOUSE DURING HEATING PERIOD USING FEED-FORWARD NEURAL NETWORKS

Vesna Ranković, Dragan Cvetković, Ilija Nikolić, Nenad Miloradović, Milorad Bojić 80

7.05. EFFICIENT CONTROL OF UNIVERSITY AUDITORIUIM HEATING SYSTEM Saša Jovanović, Milan Matijević, Milan Ristanović, Dragan Lazić 81

7.06. COOLING BUILDING BY GEOTHERMAL ENERGY: APPLICATION IN SOUTH ALGERIA Sehli Abdelkrim , Tamali Mohamed, Hasni Abdelhafid 82

7.07. APPLICATION OF ENERGY EFFICIENCY AND BIOCLIMATIC PRINCIPLES IN URBAN PLANNING Biljana Rakić, Ljiljana Mihajlović 83

7.08. DUOBLE SKIN FAÇADES – DEFINITION AND CONCEPT, HISTORICAL DEVELOPMENT, ADVANTAGES AND DISADVATANGES

Aleksandar S. Anđelković, Damir D. Đaković 84

7.09. COMPRESSED AIR SYSTEM STRUCTURE AND ENERGY EFFICIENCY D. D. Šešlija, I. M. Ignjatović, S. M. Dudić 85

7.10. COMPARATIVE REVIEW OF THE ENERGY EFFICIENCY OF THERMAL POWER PLANTS WITH THE OPEN AND CLOSED-CYCLE COOLING SYSTEM

Mirjana Laković, Slobodan Laković, Miloš Banjac, Mladen Stojiljković 86

7.11. TECHNO - ECONOMIC ANALYSIS OF THE POSSIBILITY OF COMBINED HEAT AND POWER GENERATION IN DISTRICT HEATING PLANT "ERDOGLIJA" KRAGUJEVAC

Vladimir Vukašinović, Milun Babić, Dušan Gordić, Dubravka Jelić, Davor Končalović 87

7.12. DESIGN OF SYSTEM FOR CENTRAL ASPIRATION OF WOOD DUST Vladimir Vukašinović, Dušan Gorgić, Milun Babić 88

7.13. PROPER SELECTION AND USE OF THE HOUSEHOLD APPLIANCES AS A WAY OF THE ELECTRICAL ENERGY SAVINGS

D. Adamović, N. Lukić, Z. Đorđević, V. Marjanović, S. Jovanović 89

7.14. APPLICATION OF AHP AND QFD METHOD IN THE ANALYSIS OF ENERGY EFFICIENCY Slađana Živadinović, Ivan Savić 90

7.15. A STRATEGIC APPROACH TO ENERGY AND ENVIRONMENTAL MANAGEMENT Sladjana Živadinovic, Marija Milicevic, Nada Živanovic 91

7.16. STUDY OF USAGE OF RECYCLED RUBBER CRUMBS (RRC) FOR PRODUCTION OF THERMAL INSULATION PANELS

Petar Đekić, Anica Milošević, Boban Cvetanović 92

7.17. INDUSTRIAL WASTE HEAT TO COVER DOMESTIC HEAT DEMAND -ANALYZING POTENTIAL AND DEMAND

S. Brückner, H. Schäfers, I. Peters 93

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7.18. EVALUATION OF THERMAL AND ELECTRICAL ENERGY CONSUMPTIONS IN SCHOOLS OF ČAČAK REGION

S. M. Dragićević, S. M. Stojković , S. G. Vasović 94

7.19. REVIEW OF THE CURRENT ENERGY POLICY IN THE REPUBLIC OF SERBIA WITH THE DEVELOPMENT PERSPECTIVES

Mirjana Laković, Branislav Stojanović, Mladen Stojiljković, Marko Ignjatović 95

7.20. THE ROLE OF THE INTELLIGENT BUILDING SKIN IN INCREASING ENERGY EFFICIENCY IN BUILDINGS

Milica Stojanović, Nataša Petković 96

7.21. ESTIMATION OF ENERGETIC CHARACTERISTICS OF SETTLEMENTS IN NIŠ REGION, SERBIA

Branislav V. Stojanović, Mirko M. Stojiljković, Marko G. Ignjatović, Goran D. Vučković, Mladen M. Stojiljković, Jelena N. Janevski 97

8. Energy and Environmental Aspects of Transportation 99

8.01. NEW WORLD-WIDE LIGHT-DUTY TEST CYCLE Stojan Petrović, Velimir Petrović 100

8.02. ONE APPROACH FOR IMPROVEMENT OF SPARK IGNITION ENGINE EFFICIENCY Jovan Ž. Dorić, Zoran M. Čepić, Ivan J. Klinar 101

8.03. HYDRAULIC HYBRID TECHNOLOGY REVIEW – PERSPECTIVES AND BENEFITS OF ITS IMPLEMENTATION ON PUBLIC TRANSPORTATION VEHICLES

M. Kitanović, S. J. Popović, N. Miljić, M. Cvetić, M. Tomić , P. Mrđa 102

8.04. THE EFFECT OF BIODIESEL AND BLENDED DIESEL FUEL ON EXHAUST EMISSIONS R. Gligorijević, J. Jevtić, Đ. Borak 103

8.05. ECOLOGICAL AND ENERGETIC DIESEL ENGINE CHARACTERISTICS WITH BIODIESEL Aleksandar Lj. Davinić, Radivoje B. Pešić, Stevan P. Veinović, Stojan V. Petrović 104

8.06. THE COMBUSTION CHAMBER APPRAISAL ON THE BASIS OF ITS FLUID FLOW CHARACTERISTICS

Zoran S. Jovanović, Zlatomir M. Živanović, Željko B. Šakota, Zoran M. Masonicic 105

8.07. USAGE OF SMALLER VEHICLES IN URBAN ENVIRONMENT IN ORDER TO DECREASE CO2 EMISSIONS

V. Momčilović, A. Manojlović, D. Vujanović, S. Bunčić, V. Papić 106

8.08. AUTOMOTIVE MECHATRONIC SYSTEMS – ECONOMY AND ECOLOGY

Milan Pavlović, Miloš Milošević, Dušan Stamenković, Aleksandar Stefanović, Vukašin Pavlović 107

9. Technologies and Plants 109

9.01. ENERGY EFFICIENCY IMPROVING OF COMBINED CYCLE GAS POWER PLANTS (CCGPP) AND ENVIRONMENT BENEFITS WITH TRIGENERATION AND TRIGENERATION POWER PLANTS (TPP) USED

Marijan Gacevski 110

9.02. THE ANALYSIS A CALCULATION OF WAVED EXPANSION JOINT Jelena Nikolić, Aleksandar Petrović , Aleksandra Đerić 111

9.03. EFFICIENCY ASSESSMENT OF DIFFERENT CAB AIR DISTRIBUTION SYSTEM LAYOUTS Dragan Ružić, Ferenc Časnji, Aleksandar Poznić 112

xiv

9.04. HOW TO DETERMINE WHEN DRYING INTERVALS START AND FINISH DURING GRAIN DRYING

Damir D. Đaković, Aleksandar S. Anđelković 113

9.05. COMBINED HEAT AND POWER TECHNOLOGIES - AN OVERVIEW Dejan Mitrović, Dragoljub Živković, Velimir Stefanović, Mirjana Laković-Paunović 114

9.06. ROTATING STALL IN CENTRIFUGAL PUMP RADIAL IMPELLERS Ž. M. Stamenković, J. B. Bogdanović-Jovanović 115

9.07. CONVENTIONAL AND ADVANCED EXERGETIC ANALYSES APPLIED TO AN INDUSTRIAL PLANT Goran Vučković, Gradimir Ilić, Mića Vukić, Mirko M. Stojiljković 116

10. Automatics, Process Control and Expert Systems 117

10.01. ABOUT THE DYNAMIC BEHAVIOR AND THE REGULATION OF NEW TYPE OF WIND TURBINE GEARBOX BASED ON CVT

Boban Andjelković, Dragan Milčić, Jelena Stefanović Marinović, Aca Micić, Biljana Djordjević 118

10.02. SYSTEM MODERNIZATION OF THE STEAM BLOCK AUTOMATIC CONTROL USING DCS AND SCADA SYSTEMS AND PLC CONTROLLERS

Milena Todorović, Dragoljub Živković 119

10.03. INTELLIGENT CONTROL SYSTEMS FOR AUTONOMOUS ENERGY COMPLEXES OF THE DISTRIBUTION POWER NETWORK

L. B. Director, I. L. Maikov 120

10.04. DETECTION OF THE POSITION AND ESTIMATION OF DIMENSIONS OF THE MOVING OBJECT IN THE LOW VISIBILITY CONDITIONS BY APPLYING THE TECHNIQUE OF DIGITAL IMAGE PROCESSING

Aca Micić, Biljana Djordjević, Boban Andjelković, Dragan Radenković 121

10.05. A TRACEABLE RELATIVE HUMIDITY CALIBRATION IN THE INSTITUTE “VINČA“ N.D. Milošević, N.M. Stepanić 122

10.06. LIQUID COOLING IMPLEMENTATION FOR DATACOM EQUIPMENT Sevde Stavreva, Marko Serafimov 123

10.07. EXPLOITATION RESEARCHES OF THE THERMO-ENERGETIC SYSTEM’S AVAILABILITY Dragan Milčić, Dragan Kalaba, Dragoljub Živković, Miroslav Mijajlović 124

10.08. CONTROL SYSTEMS FOR MICRO AND MINI HYDROPOWER PLANTS Vladislav. A. Blagojević, Jasmina B. Bogdanović-Jovanović, Miodrag M. Stojiljković 125

1. Plenary Session

15th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 18–21, 2011

Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering Niš

2

INTEGRATED RENEWABLE ENERGY SYSTEMS IN BUILDINGS:

POTENTIAL AND PERSPECTIVES OF LOW TEMPERATURE SYSTEMS

Agis M. Papadopoulos

Abstract. On the move towards the Near Zero or Zero Energy Building one cannot but consider low temperature, renewable energy systems as an integral part of a building’s design. This applies from active solar thermal to geothermal systems in order to provide the necessary heating and cooling, but also hot water and, aiming at a truly Zero Energy Building, to cope with part of the building services like laundering and domestic refrigeration.

It is fairly clear, that the aim of a Zero Energy Building cannot be achieved without a truly integrated Energy Design approach – and also its consequent implementation. Achieving the aim of a Zero Energy Building can be dealt with by a combination of two major tools: (a) Avoiding, postponing or reducing the generation of heating and cooling loads, by applying the basic principles of building physics. This implies the implementation of sound sun-protection schemes, the use of thermal insulation, the use of reflective and low-absorbing materials on the building’s interior, the practice of reasonable ventilation patterns and the reduction of internal thermal loads production and (b) Using alternative, renewable sources and systems to produce the heating and refrigeration necessary.

The implementation of this approach implies the use of state of the art renewable energy systems, of heat pumps, of thermal energy storage systems and techniques as they have an enormous potential to make the use of thermal energy equipment more effective, and of heat distribution systems fitting smoothly into the thermodynamic profile of the RES systems. It also implies the use of advanced controls and automation systems, as the optimum combination of all this “hardware” is rather difficult to achieve by using “traditional” controls. Finally, understanding the requirements of the user and providing adequate solutions remains the single most important prerequisite, if the design had to be successful and just a simple academic exercise.

Within this paper, the results of a study will be discussed, which assesses the potential, the limitations and the perspectives of using a combination of low temperature renewable energy systems towards the Zero Energy Building.



3

DEVELOPMENT OF THE MACEDONIAN ENERGY SECTOR

IN THE FRAMEWORK OF THE ENERGY COMMUNITY

G. H. Kanevce, L. P. Kanevce

Abstract. In order to create a competitive integrated regional energy market the Energy Community Secretariat has prepared a Regional Energy Community Strategy for the period up to 2021. The Strategy aims at identifying common tools which shall ensure that the Contracting Parties can achieve the goals set by the Treaty establishing the Energy Community and develop a competitive, secure and sustainable regionally integrated energy market. The Strategy provides a general regional framework in which national strategies can be further developed to reflect specific circumstances and priorities.

The Government of the Republic of Macedonia in 2010 adopted a Strategy for energy development in the republic of Macedonia until 2030 and a Strategy on use of renewable energy sources in the Republic of Macedonia by 2020. In the paper the relationship of the two Macedonian Strategies with the Regional Energy Community Strategy is analyzed as well as the possibilities and challenges in Macedonia to achieve the main goals underlined in the proposed Regional Strategy.

Keywords: Strategy, Energy, Energy Community



4

EXERGY ANALYSIS OF TWO-STAGE WATER TO WATER HEAT PUMP

D. Antonijević, N. Rudonja, M. Komatina, D. Manić, S. Uzelac

Abstract. The paper presents an exergy analysis of the selected two-stage compression water to water heat pump system in heating mode of operation. The foreseen heat source is underground water of constant temperature level. The characteristic exergy values are calculated for the ambient temperature 0 [oC] and ambient pressure 100 kPa. In addition, values of exergy losses, exergy efficiency, exergy loss ratio, exergy loss coefficient and exergy effectiveness (degree of thermodynamic ideality) are also calculated and analyzed. The objective to indicate components and working conditions with increased exergy losses was fulfilled and the obtained results should provide guidance for design and optimization of heat pumps that operate with underground water and are used for water heating applications.

Keywords: Heat pump, Exergy analysis, Underground water, Heating



5

EDUCATION, SCIENCE AND TECHNOLOGY – TRENDS AND ACCIVEMENTS

Vojin Grković

Abstract. Globalization and explosive enlargement of the knowledge quantum are among the largest new appearances manifested in the last decades of the twentieth century at the world stage. Starting from these appearances attention was turned to global unbalance of the development among countries, and the patterns in the global education. The main aspects of the state’s knowledge, economy and competitiveness were conceived, as well as those of provinces and regions. The existences of the knowledge infrastructure as well as the interconnection of main types of the knowledge are underlined. In that respect the knowledge core is defined and discussed. The knowledge flow potentials toward new products are discussed. The university scientist’s motivation is pointed as important knowledge flow potential, and also as the drugging force for the further development of Serbia, as well. An overview of the main indicators of the higher education in Serbia is presented. In that respect the aspects of the higher and university education future development in Serbia is conceived. The possible schemes for the compounding of higher education, scientific research, technology development and entrepreneurship were conceived targeting their high synergy achievement. The establishing of the appropriate scientific-education infrastructure in Serbia was also discussed.



6

NEW ENERGY TECHNOLOGIES AS A CHALLENGE FOR THERMAL ENGINEERS

Miodrag Mesarović

Abstract. It has been nearly a century since the world has had a comparable opportunity to change its energy system. Much of the system now in place was created in an explosion of invention that began around 1890 and was largely finished by 1910. Technologies that had prevailed for centuries became obsolete in a matter of years, and the 20th century emerged as the age of fossil fuels. The world may be at a similar turning point today. After decades of public policy support, new energy technologies are finally coming of age. Thermal engineers are and will continue to be the leaders in their deployment throughout the 21st century. This paper presents the new technological challenges facing the thermal engineers.

2. Environmental Protection



8

POLLUTANTS DISPERSION MODELING USING CLASSICAL AND

MODIFIED GAUSSIAN MODELS

Igor B. Andreevski, Gligor H. Kanevče, Ljubica P. Kanevče,

Aleksandar P. Markoski, Sevde K. Stavreva

Abstract. Pollutant transport modeling after its emission in the atmosphere is a problem that involves a large number of researchers in the world. In order to better describe pollutants dispersion, and to get more realistic definition of environment pollution we use a number of mathematical models to simulate the transport and estimate pollutant ground level concentrations. In this paper, some major characteristics of classical Gaussian models are presented, as well as changes that can be made in model algorithms in order to achieve progress in their performances. In this way we can achieve greater estimation accuracy and these models can reach characteristics of modified Gaussian models, or new generation models. As an example, the analysis of model MADAM was taken. Model MADAM was developed at the Faculty of Technical Sciences and it has gone through several transformation stages. The new algorithms were applied compared to the classical Gaussian models, a group in which it belonged in the early development stage. Also, some new methods to improve model performances were analyzed, primary inverse approach.

Keywords: dispersion modeling, Gaussian models, MADAM



9

THE CONCEPT OF CCS READY PLANTS

Sanja B. Petrović Bećirović. Đorđina Lj. Milovanović

Abstract. The problem of global warming, resulting from an increase in atmospheric GHG concentrations, has been recognized as one of the most alarming global issues of today. Activities carried out up to date indicate that if catastrophic climate change effects are to be avoided, global temperature rise must be kept below 2°C compared to the pre-industrial times. In order to achieve the goal set, global GHG emissions must be significantly reduced. Power generation sector, relying primarily on the fossil fuel combustion, has been identified as the most significant global source of GHG emissions, contributing with 41% to total GHG emissions. Consequently, coal burning power generation facilities have been recognized as the primary target for implementation of all feasible GHG emission reduction measures. Having in mind that CO2 emission reduction technologies applicable for large-scale coal power plants have not yet reached full technical and commercial maturity, EU legislation has introduced a concept of carbon-capture-and-storage ready plants. The specified concept requires all new plants to be designed in such manner as to enable later integration of CCS systems, once the systems become technically proven and commercially available. The paper provides a clarification of the much speculated definition of CCS ready plants, defining all requirements that need to be taken into account when designing a CCS ready plant.

Keywords: GHG emissions, energy generation, CCS ready plants



10

A METHOD FOR DEFINING STREETS AS SOURCES OF CO2 EMISSION

AND THEIR CLASSIFICATION IN THE CITY OF NIŠ

Mladen Tomić, Predrag Živković, Gradimir Ilić, Mića Vukić, Jelena Milisavljević, Petar Đekić

Abstract. Traffic is one of the main sources of CO2 in Serbia, as well as in the world. The subject of this study is to determine city streets as sources of CO2 emission in south Serbian city of Niš. In order to make these possible, measurements were carried out of frequency of traffic at critical intersections in the city, measurement of the concentration of CO2, as well as monitoring of a direction of the vehicle at the crossroad. Based on these data, the connection has been established between the traffic flow at crossroads, and traffic flow on the roads, between monitored crossroads, enabling the definition of CO2 emissions on the road. Also, this makes it possible to perform classification of streets according to their annual emissivity.

Keywords: COPERT, CO2, emission, traffic



11

TRAFFIC AND POLLUTION IN THE CITY OF NIŠ

Predrag M. Živković, Mladen A. Tomić, Gradimir S. Ilić

Abstract. The air quality is very important for the quality of living in modern cities. It is known that the traffic is the single largest pollutant in Europe. Therefore, proper treatment of this component of pollution is very important for precise estimation of pollution levels. In this paper, specific approach for measurement of roadside CO2 concentration, as the tracer gas, is analysed. TESTO 454 gas analyzer have been used for CO2 concentration measurements. The wind speed and direction have been measured on several locations in the City of Niš, considering that pollution distribution is globally determined by wind characteristics, and for wind measurements cup anemometer was used. For wind data collecting, specific measuring system was developed, a well as the software needed. Traffic intensity have been measured on six major crossroads in the City. The data obtained were used to estimate the traffic generated CO2 emission on the major streets in Niš. Given methodology shows possibilities for further implementation of other pollutant components measurement, which will allow tracking of main pollution pathways.

Keywords: traffic intensity, CO2 concentration, measurement, data analysis



12

INFLUENCE OF TRAFFIC ON THE CITY OF NIŠ AIR QUALITY

Predrag M. Živković, Mladen A. Tomić, Gradimir S. Ilić

Abstract. Air quality in urban areas is being influenced by many factors, mostly anthropogenic. Proper estimation of pollutant distribution is very important for making decisions for air quality improvement. Application of CFD techniques is giving the most detailed information about pollutant dispersion. If we consider pollution a problem, application of CFD techniques is not a solution for the problem, but an estimation tool, which gives the data needed to the environment protection experts. In this paper, measured traffic intensity is used for defining initial and boundary conditions in the CFD model. For this usage, COPERT software package is used. As being well known that wind characteristics have the largest influence on pollutant dispersion, they were carefully treated. There are two main wind directions on the City of Niš area, so two groups of simulations were done, for each main wind direction separately. For pollutant dispersion estimation PHOENICS software package was used. For each wind direction, two simulations were done, considering the traffic intensity distribution, one for the morning traffic minimum, and other for the afternoon traffic maximum, considering measured wind data at the same time. The results of the numerical simulation shows good agreement with the measured wind data and CO2 concentrations.

Keywords: traffic intensity, CO2 concentration, CFD, PHOENICS



13

GASIFICATION PROCESSES OF THT ORGANIC WASTE

WITH PRODUTION OF THE ELECTRICAL ENERGY

Ranko Zrilic

Abstract. Gasification is the process of converting carbonaceous materials such as coal, petroleum, biomass and waste into combustible gases (carbon monoxide and hydrogen)that ideally contain all the energy originally present in the feedstock. In practice energy conversion effiencies lie between 70% and 90%. Gasification is achieved by thermally organic materials in the absence of adequate air to support full combustion. Gasification of organic materials is not a new subject. It was widely employed during the Second World War with approximately one million gasifies used to operate cars, trucks, boats, trains and electricity generators in Europe. The possibility of using gasification for organic waste disposal is an application that has arisen as a results both public pressures for environmental improvement coupled with wish to derive commercial benefit from the energy of such wastes. Bellwether Gasification Technology uses gasification to convert all calorific waste into s clean combustible gas, vitrified slag and high-value energy product with no impact on the environment through the development of its innovative Technology.



14

ENVIRONMENTAL BENEFITS OF USING MUNICIPAL SOLID WASTE

AS AN ENERGY SOURCE-CASE STUDY: SERBIA

Dušan Marković , Gordana Stefanović , Mladen Tomić, Goran Vučković, Biljana Milutinović

Abstract. Large quantities of waste which are being disposed of near major cities and settlements in the Republic of Serbia have a negative impact to human health and the quality of life in general. Increasing quantities of waste are asking for systematic planning and implementation of waste management in a sustainable manner. On the other hand, waste has big energy potential, which could substitute fossil fuels. Since waste is renewable energy source, and more than 50% of waste in the Republic of Serbia is organic waste (carbon neutral), it is recommended that energy from waste be recovered. This paper focuses on environmental benefits, in terms of global warming potential and acidification potential, by substituting fossil fuels with municipal solid waste in the Republic of Serbia. An energy transformation efficiency equal to or greater than about 25 percent results in an allowable average substituted net energy potential that renders the emission of waste incineration plants (calculated as CO2 equivalents) climate-neutral due to the emission credits from the power plant mix.

Keywords: energy from waste, municipal solid waste, ghg emissions from waste incinerator

3. Mathematical Modeling and Numerical Simulation



16

NUMERICAL PREDICTION OF OVERFIRE AIR INFLUENCE ON FEGT AND NOX

EMISSION IN 350 MWe PULVERIZED COAL UTILITY BOILER

V. B. Beljanski, I. D. Tomanović, S. V. Belošević, M. A. Sijerčić, B. D. Stanković,

N. Đ. Crnomarković, A. D. Stojanović

Abstract. Emission of NOx from coal fired boilers is of great concern to environmental protection. One method for NOx reduction in coal fired furnaces is OFA (overfire air). This work presents the numerical investigation of OFA port parameters for possible retrofit of tangentially-fired furnaces of the power plant Kostolac-B boiler units. The goal was to determine influence of various OFA parameter combinations (dimensions, position and flow through OFA) on NOx emission for various operating conditions. Technical requirement, necessary for proper operation of the boiler, was to maintain the furnace exit gas temperature (FEGT) in certain range. Simulation was performed by an in-house developed software validated against experimental data. The model is based on k-ε model of turbulence with Eulerian-Lagrangian approach to multiphase flow, six-flux method for radiation modeling and heterogeneous reactions model. The NOx submodel is focused on homogeneous reactions of thermal NO and fuel NO formation and destruction. Obtained results show significant NOx reduction (up to 24,1%) for operating condition which before OFA modification had high FEGT and NOx emission, up to 7,7% for operating condition with high FEGT and good NOx emission and up to 4% for operating conditions with good FEGT and NOx emission.

Keywords: Numerical simulation, Pulverized coal boiler, NOx emission, Overfire air



17

REVIEW OF SOFTWARE FOR SIMULATION AND OPTIMIZATION OF ENERGY SYSTEMS

Marko M. Mančić, Dragoljub S. Živković, Velimir P. Stefanović, Milan Lj. Đorđević, Saša R. Pavlović

Abstract. Constant increase in energy consumption and demand, followed by the inevitable green house gas emissions conveys new challenges in the terms of energy efficiency and sustainable development. Global challenge of sustainable development implies increased renewable energy utilization, improving the efficiency of energy conversion, lower gas emissions and reducing dependency on fossil fuels. Systematic approach with integration of processes and technologies into polygeneration systems reveals overall benefits of combined technologies, and pinpoints integration conditions and possible problems. Fulfillment of these conditions is followed by a substantial use of financial resources. Due to complicated structure and complex infulences between parametars which define the techno-economic operating conditions of these systems their optimization is a necessity. Until now, manz softwares with abilities for different simulations and optimizations of energy systems have been developed. The objective of this paper is to determine and compare features of these software, thus pinpointing tools most suitable for the mentioned challenges of energy system design and integration. For this purpose, a comparative analysis of available energy system software is carried out and presented. Features, advantages/disadvantages are discussed and remarks about features, inputs/outputs, technologies included and possibilities for integration and system optimization are made. As a result, software with most tools and most flexibility are identified.

Keywords: Energy system simulation, polygeneration, optimization, process integration, software



18

MODELING OF SMALL SCALE POLYGENERATION SYSTEMS

Marko M. Mančić, Dragoljub S. Živković, Velimir.P. Stefanović, Saša R. Pavlović

Abstract. Fulfilling conditions of any country’s sustainable development implies the application of measures of energy efficiency, renewable energy sources, reduction of environment pollution and green house effects. One of the most effective measures for increasing energy efficiency is the use of polygeneraton systems for simultaneous heating, cooling and electricity production. In this way, a substantial increase in overall efficiency is achieved, and thus, indirectly, a reduction of pollution and green house gas emissions. Small scale polygeneration systems involve a combination of conventional and new technologies for heating cooling and electricity production, but also other products such as CO2, bio-fuels etc

In order to design and make an integration and optimization of such energy systems, a mathematical model of the system has to be introduced. Possible approaches and methods for modeling of small scale polygeneration systems are presented in this paper. Mathematical models of components of these systems are presented, and methods for their connection are discussed. Components included in the model are small gas turbines, gas engines based on OTO cycle, and heat exchangers. Possibilities for finding solutions for the mathematical model numerically are discussed.

Keywords: Energy system modelling, small scale polygeneration, process integration



19

MODELING OF FLUE GAS TEMPERATURE INFLUENCE ON

POLLUTANT PRODUCTS EMISSION DURING THE BIOMASS COMBUSTION

B. S. Repić, A. D. Marinković, G. S. Živković, S. Dj. Nemoda, B. D. Grubor

Abstract. Biomass combustion is followed by emission of many pollutants, i.e. NO, NO2, CO, CO2 and in small amount SO and SO2 compounds. In order to find a suitable method for organizing the combustion process, it is necessary to analyze the influence of temperature on combustion pollutant products emission. Such an analysis is being performed by computation of the chemical thermodynamic equilibrium composition of the system, which yields the equilibrium composition of flue gases with respect to the combustion temperature. The thermodynamic computations of the chemical equilibrium enable reducing the range experimental investigations and estimating the probability of particular reactions. In the paper presented are the results of an application of the developed model on computation of chemical thermodynamic equilibrium of a system formed by compounds and elements contained in fuel (biomass) and combusted air. The results are obtained at temperatures from 800-1700 K, pressure 1 bar, excess air α = 1.0, 1.50, 2.0, 2.5 and 3.0, moisture content W = 10, 20, 30, 40 and 50%, and for several different types of biomass. For practical application of computation results in the paper presented are the results of measurements of the local furnace temperature conditions at 1.5 MW and 75 kW boilers burning baled biomass.

Keywords: Biomass; emission; modeling; chemical thermodynamic equilibrium



20

MATHEMATICAL SIMULATION AND OPTIMIZATION

OF AUTONOMOUS SOLAR-WIND ENERGY INSTALLATIONS

O. S. Popel, S. E. Frid, A. V. Mordynsky

Abstract. The paper presents some results of autonomous combined solar-wind energy installations mathematical simulation to justify their optimal configurations taking into account real climatic conditions of operation and load curve. Mathematical models of components of a system, consisting of wind installation, PV-panels, battery and control unit have been developed and system dynamic simulations have been carried out for climatic conditions of different Russian Federation regions using TRNSYS simulation tool to optimize technical and economical parameters of the systems.

Two typical load schedules have been considered: one is a constant load, another – street lighting load. It has been shown that combination of solar and wind installations provides development of fully autonomous energy systems in most climatic conditions of Russia with better economical indicators then only wind or PV installations.

The relationships between rated electrical load, installed powers of wind and PV installations as well as battery capacity necessary for all-year consumer energy supply with minimal expenditures at different climatic conditions have been received. It has been shown that optimally configured wind-solar autonomous energy systems could be competitive in comparison with traditional autonomous energy installations at noticeable part of Russian territory and have good prospects for implementation. In some cases conversion of surplus of generated be primary energy sources during some periods of time electricity into heat, accumulated in a solid-phase heat storage, is reasonable to supply a consumer not only with electrical energy but with heat, that could improve system economical parameters.

Keywords: autonomous solar-wind system, solar-wind street lamp



21

COMPARISON OF DIFFERENT INDIVIDUAL SOLAR WATER HEATER TYPES

EFFECTIVENESS FOR CLIMATIC CONDITIONS OF RUSSIAN REGIONS

S. E. Frid, Yu. G. Kolomiets, E. V. Sushnikova

Abstract. Simulation of solar water heaters (SWH) operating in climatic conditions of different regions of Russian Federation has been carried out using TRNSYS simulation tool. Three general classes of SWH have been considered: integrated collector-storage unit, flat-plate solar collector with separate heat storage tank and vacuum tube solar collector with storage tank. All SWHs had 100 l water storage tank volume and was directed to supply 100 l of hot water per day.

It has been shown that collector-storage unit is the most efficient for seasonal (warm period of year) hot water supply, whereas for all-year operation the most efficient is traditional installation with separate storage tank (especially for large systems).

Moderate temperatures of water that is necessary for hot water supply eliminate the advantage of low heat losses of vacuum tube collectors. So the thermal efficiencies of systems with flat-plate and vacuum tube solar collectors, that have the same gross area, are almost equal. However intensive growth of vacuum tube collectors mass-production leads to reduction of their price below the price of flat-plate collectors that provides for vacuum tube collectors some advantages.

Keywords: solar water heater, integrated collector-storage unit, flat-plate solar collector, vacuum tube solar collector



22

SOLVING THE PROBLEMS OF

HIBRID AUTONOMOUS POWER-GENERATING UNIT OPTIMIZATION

I. L. Maikov, L. B. Director

Abstract. We propose a general model of a power-supply unit, a computational routine for circuit design analysis and optimization, and software that accurately accounts for the changes in the consumption schedule and solves the optimization problems for long time horizon. Simplex method with artificial basis is used in an iterative process to minimize the goal function that depends on the criterion chosen (costs, primary resources consumption, or environment). Decomposition method is employed due to high dimensionality of the problem.

Keywords: mathematical modeling, optimization, numerical methods, power-generating unit, linear programming



23

USAGE OF METHODS OF OPTIMIZATION FOR SELECTION OF CONSTRUCTIVE

CONCEPTION OF FACILITIES OF SMALL HYDRO POWER PLANTS ON PREVIOUSLY

SELECTED MACRO LOCATIONS BY METHOD OF MULTY CRITERIA RANKING

Zdravko N. Milovanović, Darko Knežević, Aleksandar Milašinović,

Svetlana Dumonjić-Milovanović, Jovan Škundrić

Abstract. Article considers usage of optimization method regarding the selection of optimal concept of facilities of SHPP (Small Hydro Power Plants) from the point of view of selection of options within already defined space. For selected qualitative and quantitative characteristics relative ponder (weighted) coefficients are set through the mixture of AHP (Analytical Hierarchical Process), Saaty - scale and primary defined parameters. Within specified problem we deal with alternatives which are defined through qualitative criteria, without precise parameters which gives an impression that existing multi criteria method should be adjusted for solving such problems of ranking alternative solutions by gradual reduction of prior starting multi criteria. Described optimization method is applied on selection of system of Small Hydro Power Plants on Sućeska River as part of Drina River that was later designed, constructed and initiated into regular exploitation.

Keywords: Small Hydro Power Plants (SHPP), optmization method, multi criteria, ranking alternative



24

MODELING OF POLLUTANTS AT THE LANDFILL WASTE

Sonja Stefanov, Rade Biočanin

Abstract. Paper presents modelling of pollutants at the landfill waste. Uncontrolled fire on landfill where are tyre produce a lot of smoke and air pollutants, including benzene and polycyclic aromatic hydrocarbons (PAH). Great heat leads to the generation of pyrolytic oil which, when mixed with the fire extinguishing agent, contaminates the surrounding soil, surface water and underground water. Paper analyzes and presents in particular the emission factors of incomplete burning of waste car tyres. Metal dust emissions have been presented, volatile organic compund (VOC) emissions, slightly volatile organic compound (SVOC) emissions and emissions of polycyclic aromatic hydrocarbons (PAH). Evaluation of the effect on the air quality has been graphically presented by modelling of uncotrolled tyre burning by using EPA "SCREEN 3 MODEL".

Keywords: modeling, pollutants, landfill, air, tyre, emissions



25

CALCULATION OF FAN OPERATING PARAMETERS FOR DIFFERENT NUMBERS OF

REVOLUTIONS, CONSIDERING THE INFLUENCE OF REYNOLDS NUMBER

B. P. Bogdanović, J. B. Bogdanović-Jovanović, S. Milanović

Abstract. Fan operating parameters for different numbers of revolution of the fan runner, typically provided by fans manufacturers, are obtained by calculation of experimentally determined operating parameters for one specific number of revolution (which is usually the maximum operating number of revolution for the certain fan). These recalculations are usually done by disregarding the influence of Reynolds number on the mechanical losses of flow energy in the fan. This approach can lead to considerable errors for low Reynolds numbers. In this paper data of Reynolds number’s influence on the fan efficiency are given. According to experimentally obtained data is also derived formula for recalculating the functional characteristic of centrifugal fan efficiency due to alteration of numbers of revolution, taking into account the influence of Reynolds number. Changing of fan efficiency characteristic considering the influence of Reynolds number causes the changing of other operating parameter characteristics as well, as is represented in the paper.

Keywords: fan, operating parameters, number of revolution, Reynolds number, fan efficiency



26

MONTE CARLO RANDOM WALK METHOD FOR SOLVING LAPLACE EQUATION

Mladen Tomić, Predrag Živković, Mića Vukić, Gradimir Ilić, Žarko Stevanović

Abstract. In this article a stochastic Random Walk Method was implemented and investigated for solving Laplace equation. In this paper will be considered on a case of 2D stationary heat conduction; a thin plate, which upper and bottom sides are adiabatically insulated, has been exposed to different temperatures on the boundaries. The method is based on random movements through domain. After each movement, a result has been obtained in the point of arrival. The analysis presented in the article, have show that RWM solution is convergenting. The results for various number of random walks were compared mutually and with analytical solution Based upon for this examples an error analysis was performed. Simplicity and accuracy are the main features of the method.

Keywords: Heat conduction, Laplace equation, Monte Carlo method, Random walk method



27

RESIDENTIAL BUILDINGS’ SUSTAINABILITY BY NON-LINEAR NORMALIZATION

B. Vučićević, M. Stojiljković, N. Afgan, V. Turanjanin, M. Jovanović

Abstract. This paper presents the mathematical procedure for the determination of overall sustainability index of nine options for the agglomeration of economic, environmental and social indicators. Eleven sub-indicators were selected and calculated for all chosen options. In accordance to final energy consumption (for space heating, hot water production, cooking and the household electrical appliances) the selection, defining and determining the economic, social and environmental indicators was developed. It was done for all selected options of residential buildings (single family houses and multi apartment buildings).

Investigation of the influence of non-linear normalization on the sub-indicators' agglomeration was the aim of this paper. Normalized sub-indicators are obtained by selection of the appropriate linear (θ=1) or non-linear function (θ≠1). Sustainability index and its standard deviation were calculated for different value of the parameter θ and each option. The functional dependence between the sustainability index and the associated standard deviation of the θ parameter (characterizing the way of normalization) was obtained.

Keywords: Sustainability Index, building, ASPID method



28

ABOVE GROUND PIPING UNDER THE INFLUENCE OF RADIATION

Marko N. Ilic, Velimir P. Stefanovic, Gradimir S. Ilic, Saša R. Pavlović

Abstract. This paper presents one of the possible accidental situations during transportation of gas and tends to contribute in defining a practical response of workers in such situation.

Within natural gas processing plants such as compressor stations, the piping is partially located above the ground. In the rare incident of a gas leakage on these high-pressure facilities, a supersonic compressible gas jet will form. This jet may ignite and burn, causing a considerable radiation heat flow rate impinging on the surface of above-ground pipes located in the vicinity of the leak.

As a consequence of heat impingement on the pipe surface will be, change of material properties (decreasing of strength) at high temperatures. In order to avoid greater rapture a reasonable pressure relief rate needs to be applied.

Main goal to implement was the numerical calculation of the radiation heat flux on the surface of the pipe with the CFD software package FLUENT (software was exploited in German gas company E.ON Ruhrgas). Achieved results were used as a boundary condition in an additional calculation of time resolved wall temperature of the pipe. From these results some conclusions about technical response were derived.

Keywords: non-premixed combustion in jet; thermal reach of jet



29

MATHEMATICAL MODEL AND NUMERICAL SIMULATION OF

CPC-2V CONCENTRATING COLAR COLLECTOR

Velimir P. Stefanović, Saša R. Pavlović, Marko V. Mančić, Andrijana D. Stojanović,

Milan Lj. Đorđević, Žarko Janković

Abstract. Physical and mathematical model is presented, as well as numerical procedure for predicting thermal performances of the CPC-2V solar concentrator. The CPC-2V solar collector is designed for the area of mid temperature conversion of solar radiation into heat. The collector has high efficiency and low price. Working fluid is water with laminar flow through a copper pipe surrounded by an evacuated glass layer. Based on the physical model, a mathematical model is introduced, which consists of energy balance equations for four collector components. In this paper water temperatures in flow directions are numerically predicted, as well as temperatures of relevant CPC-2V collector components for various values of input temperatures and mass flow rates of the working fluid, and also for various values of direct sunlight radiation and for different collector length.

Keywords: thermal, solar radiation, performance, model, unsteady state analysis



30

STABILITY ANALYSES OF A GUYED MAST EXPOSED TO DYNAMIC WIND ACTION

M. Pezo, V. Bakić, Z. Marković, Ž. Stevanović

Abstract. The interaction of a flexible structure with a flowing fluid by which structure is surrounded gives rise to a rich variety of physical phenomena with applications in many fields of engineering, for example, the stability and response of guyed masts to wind. The guyed masts are used for meteorological measurements, wireless communication or for power transmission. For understanding these phenomena is necessary to model both the structure and the fluid. The tower analyzed in this paper is an 80 m tall guyed mast which consists of 13 segments with two levels of guys and a ground exposure. The behavior of the mast is non-linear due to its slenderness and compliant guyed-support system. The sensitivity of such guyed mast to dynamic excitation by wind attains considerable importance. Dynamic excitation of the masts is mainly caused by the gustiness of the wind. The influence of the gravity is also taken into account. The commercial finite element software ANSYS was used for finite element modeling and numerical simulation of a thin-walled guyed mast structure response to dynamic wind action. ANSYS CFX software was used for fluid dynamics simulation.

Keywords: guyed mast, wind load, fluid-structure interaction



31

DYNAMICAL ANALYSIS OF COMBINED WIND-PHOTOVOLTAIC ENERGY SYSTEM

V. Bakić, M. Pezo and M. Zivković

Abstract. The technical analysis of a combined wind-photovoltaic energy system with hydrogen gas storage was studied. The market for distributed power generation based on renewable energy is increasing, particularly for stand-alone mini-grid applications. This paper presents the dynamical simulation and analysis of energy system consists of different wind turbines, photovoltaic arrays and an electrolyser whit tank. The analysis is based on transient system simulation program TRNSYS 16. The purpose of the study is to design a realistic energy system that maximizes using the renewable energy and minimizes using the fossil fuels. The technical analysis has done for Typical Meteorological Year (TMY) for region of Kopaonik national park. In this paper also CO2 emissions reductions is analyzed.

Keywords: wind-photovoltaic, hydrogen storage, dynamical simulation, TRNSYS



32

OPTIMIZATION OF OPERATION OF ENERGY SUPPLY SYSTEMS WITH

COGENERATION AND ABSORPTION REFRIGERATION

Mirko M. Stojiljković, Mladen M. Stojiljković, Bratislav D. Blagojević

Abstract. Energy supply systems with cogeneration can provide economic, energetic and environmental benefits due to their higher overall efficiencies compared to their most commonly used separate production alternatives. These benefits might be even more significant if cogenerated heat is used during summer months for cooling with an absorption refrigerator. In addition to that, thermal energy storage is often used because it is very convenient for peak shaving enabling cogenerator to operate continuously at nominal conditions while loads vary.

Optimization of operation parameters of such energy supply systems is important as a component of entire optimization process (including also optimization of synthesis and design parameters) in pre-construction (planning, identification and design) phases, but also in the process of short term energy production planning and for optimal control of the plants. Objective of energy supply systems optimization is usually some economic parameter, while constraints might be technical, energetic, environmental, legal, etc.

In this paper, operational optimization approach for energy supply systems with small and medium scale cogeneration, absorption refrigeration and thermal energy storage is proposed. Optimization problem is defined as mixed integer nonlinear and solved using combination of binary or integer genetic algorithms and classical linear programming techniques, i.e. dual simplex and interior point methods. The solver used is a component of “ESO-MS” software solution for simulation and optimization of energy supply systems, built on the .Net Framework.

Partial load performances of the system components are taken into account, as well as the dependence of the performance characteristics on other parameters such is environment temperature. This approach also allows definition of heat demands at multiple temperature levels, indicating from which source each demand might be satisfied.

Keywords: Optimization, Cogeneration, Absorption refrigeration, Genetic algorithms, Linear programming

4. New and Renewable Energy Sources



34

RENEWABLE ENERGY SOURCES IN RUSSIA:

PROBLEMS AND PROSPECTS OF WIDE UTILIZATION

O.S. Popel, V.E. Fortov

Abstract. Presentation will give information concerning renewable energy resources distribution on the territory of the Russian Federation (solar, wind, biomass, small-hydro, geothermal, tidal, etc.) and experience of Russian organizations in their development and practical utilization.

Despite that Russia is considered as an energy superpower and meets not only domestic needs in fuel and energy, but also supplies energy resources to Europe and Asia the energy situation in many Russian regions is not so well-being. Unlike European countries, the USA, Japan and other developed countries, where renewable energy sources are being already widely used, in Russia, centralized energy supply systems cover only around 1/3 of its territory. Decentralized power supply zones populated by around 20 million people. The energy installations here are fired with liquid fuel that is expensive due to transport costs, or use traditional local resources (coal, firewood, peat, etc.). Relatively inexpensive natural gas is piped to slightly over 50% of towns and about 35% of rural communities.

In the presentation examples of different renewable energy sources effective utilization for production of electric power, heat, and alternative fuels will be considered and most promising niches for their future implementation will be described.

Keywords: renewable energy sources, Russia



35

MODERN TECHNOLOGY FOR SUSTAINABLE EXPLOITATION OF GEOTHERMAL ENERGY

Dragoljub S. Živković, Dragan S. Milčić, Dejan M. Mitrović, Marko V. Mančić

Abstract. In Serbia, there are more than 60 hydrogeothermal low-temperature convective systems (T<150oC). Estimated energy reserves of geothermal resources are about 800 MWt, but utilization of this is low, only about 80 MWt. Utilization of geothermal energy is mostly of the cascade type, with a few examples of integrated utilization. Integrated utilization combines the use of gas, oil, and electric power for heat pumps. According to the installations already built, utilization of geothermal energy is mostly for balneological purposes and tourism. From an energy point of view, utilization of geothermal energy is mostly for heating of buildings and greenhouses.

In Serbia the use of hydro-geothermal energy for the generation of electric power is possible at several localities applying "flash steam" technology and the "binary system" method. With the use of "flash steam" technology (T>130 oC) and "binary system" technology (T>80 oC) it is possible to generate electric energy from geothermal fluids that have considerably low temperatures. In the territory of Serbia there are several convective hydrogeothermal systems in which the highest temperature of hydrogeothermal fluids may reach 150 oC. Owing to this fact it may be stated that the generation of electric energy is possible in this region.

This paper presents modern technology for sustainable exploitation of geothermal energy.

Keywords: geothermal resources, utilization, balneology, greenhouse, heat pump



36

THE POSSIBILITY ADVANTAGE OF GEOTHERMAL WATERS OF SIJARINSKA SPA

Dragan T. Stojiljković, Nebojša Č. Mitić, Andrija Šmelcerović

Abstract. Geothermal water of Sijarinska Spa was having a significant energy potential. Well B-4 in Sijarinska Spa is able to exploit to 30L/s of water temperature 75oC. This worked there are structure and tendency to create deposits in the pipe installation. Investigation of the composition was performed by standard physical and chemical methods. Was determined by the saturation index (L.I.) and Ryzner stability index (R.I.) and measure of the tendency to create deposits. The results indikate that the value of the L.I. and R.I. for geothermal water of Sijarinska spa (well B-4) were 1.45 and 4.6, respectively. The obtained values show that the geothermal water of B-4 is more favorable for use in pipe installations, since it indikate bigest tendency to create deposits. The not decrease of deposits, not come to aggressive effects in material of pipe installations.

Keywords: water, deposits, deposits creations, L.I., R.I



37

GEOTHERMAL ENERGY IN VOJVODINA - POTENTIAL, UTILIZATION,

POSSIBILITIES AND LEGAL REGULATIONS

Milovan M. Medojević, Milana S. Perić

Abstract. Republic of Serbia is characterized by high import dependence for the energy, which causes low security of energy supply. Plants where the energy transformations are performed are becoming absolutely inefficient according to modern standards, and the exploitation of renewable energy is still in its infancy. Bearing in mind all previously mentioned, the theme and goal of this paper is to point out and if possible raise the current level of awareness of energy use and potential of renewable energy to a higher level. In this paper, attention is devoted to geothermal energy and its potential in Vojvodina. Utilization of this energy is minimal, but not because this potential is not recognized, but for non-existing legal regulations related to the exploitation of these types of resources. More efficient and effective use of resources could affect the reduction of import dependence of Vojvodina, as well as increasing security of energy supply. In the further text the data of the geothermal features of the region, the methodology by which this potential is estimated, the current situation regarding utilization of this potential and existing regulations in this area are displayed.

Keywords: Geothermal energy, potential, utilization, legal regulations



38

POSSIBILITIES FOR USING VINEYARD PRUNNING BIOMASS IN SERBIA

Ivana Radojević, Gordana Stefanović, Marko V. Mančić,

Dušan Marković, Zorica Ranković Vasić

Abstract. Compared to other renewable energy sources in Serbia, biomass has the largest estimated potential accounting for around 63% of the total estimated renewable energy potential. Although, agricultural biomass accounts for one of the most important biomass sources in Serbia, agricultural biomass seldom utilized and treated as waste in most cases instead. This paper presents analysis of energy potential of vineyard pruning residues biomass in Serbia, and investigates the possibilities of its future utilization. Areas covered with vineyard and sustainable energy challenges together imply the necessity of further development and utilization of the vineyard biomass potential and investigation of conditions for its successful utilization. In this paper, the analysis of good practices in the terms of vineyard pruning residues and biomass utilization is conducted. The collected date of heating values of various sorts of vineyard residues in Serbia obtained by measuring in laboratory can be used in further research

Keywords: biomass, vineyard residues, renewable energy sources, energy potential



39

SMALL SCALE PLANT FOR COMBINED HEAT AND POWER GENERATION

UTILIZING LOCAL BIOMASS

B. S. Repić, D. V. Dakić, D. M. Đurović, A. M. Erić, M. J. Paprika

Abstract. Republic of Serbia has 4.3 Mtoe of renewable energy resources, of which 2.7 Mtoe in biomass. Currently only a small amount of biomass is used for energy production. The best way to use waste biomass for energy production is in industrial plants or district heating. One of the most efficient way, recommended by many institutions around the world, the combined production of heat and electricity with the least possible consumption of energy his own, and without disturbing the balance in food production. This paper presents the results of the construction of plants for combined heat and power (CHP plant) to cigarette type biomass combustion from agricultural production. The plant would be realized within the PKB Corporation that has great potential in agricultural biomass. The project envisages that the CHP plant is used for heating greenhouses and various social structures deployed in the region, and that parallel is the production of electricity. Now for this purpose using liquid fuel that would be replaced by biomass. The paper presents the details of this project and the choice of technology for electricity production in cogeneration plants Organic Rankin cycle.

Keywords: Biomass; CHP plant; generation; technology



40

MODELING OF TRANSPORT PHENOMENA DURING

BALED SOYBEAN RESIDUES COMBUSTION

Aleksandar M. Erić, Dragoljub V. Dakić, Mirko S. Komatina,

Stevan Đ. Nemoda, Branislav S. Repić Milica. R. Mladenović

Abstract. This paper presents numerical and experimental investigations of complex and interrelated physical and chemical phenomena that occur during combustion of baled soybean residue in the furnace with the cigarette type of combustion. The result of comprehensive research is reactive flow model of biomass combustion inside furnace. Model is described by set of partial differential equations which define momentum, heat and mass transfer processes in porous and fluid system. The main aim of developed CFD model is numerical simulation of combustion process inside the pushing furnace. It is also used to provide deeper insight in complex processes occurring during biomass combustion.

Verification of proposed numerical model was performed through comprehensive experimental researches conducted on the experimental-industrial plant of 1.5 MW boiler for heating the greenhouses in the “Agricultural Corporation in Belgrade”. Investigations were included measurement of input and output values on the furnace surfaces that are taken as the boundary of the developed model. Comparison of the results showed satisfactory agreement with numerical results, so that the developed mathematical model could be used to analyze the effects of structural and parametric changes to the facility from the standpoint of energy efficiency and ecology

Keywords: baled biomass, combustion, modeling, experimental



41

SOLAR ORGANIC RANKINE CYCLES

Milan. Lj. Đorđević, Velimir P. Stefanović, Marko V. Mančić, Saša R. Pavlović, Žarko Janković

Abstract. Organic Rankine Cycle (ORC) technology is commercially available and has been successfully applied in past decades, mainly for generating electricity from low temperature heat sources. With the help of green power certificates, ORC – solar thermal collector couples were found very attractive as renewable energy applications, especially in small scale applications.

The objective of this paper is to show complexity of modeling and optimization of ORC engines using currently available solar thermal collectors to drive ORC. Selection of the most appropriate working fluids according to the type of solar collectors used in each case optimizes the global ORC-thermal solar plant efficiency. Operating temperature is optimized as a compromise between high ORC cycle efficiency and solar plant efficiency that decreases as this temperature increases. Technology review followed by practical research is shown in order to determine technical and economical feasibility of transferring this technology to real applications. Since heat guided ORCs do not necessarily have a large operational range on a comparably high efficiency level, some dependencies that influence electric cycle efficiency in a negative way were observed.

Keywords: Organic Rankine Cycle (ORC), Solar thermal energy, energy efficiency



42

ELECTRIC ENERGY GENERATION AND CO2 EMISSIONS BY PV SYSTEMS

Jasna Radulović, Dragan Taranović, Mirko Blagojević, Jasmina Skerlić, Milorad Bojić

Abstract. The objective of this paper is to review the existing knowledge on the energy requirements for manufacturing of photovoltaic (PV) systems and to give some representative calculations for the energy pay-back time and the CO2 emissions. The paper will also report the effects of the future enhancements in the PV production technology to evaluate the long-term prospects of PV systems use for CO2 mitigation. Both the c-Si and thin film module technologies are analyzed. The CO2 mitigation potential and the importance of PV systems for the sustainable development are also highlighted. In addition, this paper reviews the energy viability of the photovoltaic energy technology to answer the question whether the PV systems can generate the sufficient energy output in comparison with the energy input required during production of the system components.

Keywords: Photovoltaic systems; Energy pay-back time; CO2 emissions



43

APPLICATION OF SOLAR ENERGY IN STREET LIGHTING DESIGNING

Kristina Zubović

Abstract. The main objective of this paper is to show, by means of a block diagram, the basic elements needed for the designing of street lighting. As an example we took the block diagram of the system of 14 LED lights powered with solar energy, with power of 30 W each one, which are placed at the exit of a city. Block diagram showing this solar power system includes LED flashlight, solar panel, two solar GEL batteries, controller, pole lamps, mounting material, and cabling. Of particular importance is the positioning of LED lighting.

Keywords: street lighting, solar LED lighting, solar panel



44

WIND ENERGY POTENTIALS ON STARA PLANINA MOUNTAIN

Predrag M. Živković, Dušan LJ. Petković, Mladen A. Tomić,

Gradimir S. Ilić, Žarko M. Stevanović, Andrijana D. Stojanović

Abstract. The main goal of this paper was to obtain all acceptable locations for siting of wind turbines on Stara Planina (Balkan) mountain. Finally, 705 locations are accepted, which covers the most of the area of Stara Planina mountain. The simulations are mostly performed using the WAsP simulation software. The results are compared by means of the quality and quantity of the wind data and load factor. Finally, the economical analysis of the acceptabillity of the installing of wind turbines was done.

Keywords: energy, wind turbine, WAsP, WindSim, assessment



45

WOOD CHIPS PRODUCTION - LOCATIONS AND WOOD CHIP

PRODUCTION EQUIPMENT

Dejan Mitrović, Branislav Stojanović, Mladen Stojiljković, Jelena Janevski, Marko Ignjatović

Abstract. Biomass is already the most important Renewable Energy Source in Europe with a huge potential for further expansion. The future development of biomass should follow some basic principles such as high conversion efficiency, competitiveness and sustainability. The experience proves that the use of biomass to produce heat complies in an optimal way with these principles. Biomass for heat can be used in small scale units for individual houses, in heat contracting projects, in district heating and in the industry. In any case the supply of high quality biomass be it firewood, wood chips or refined wood is of essential importance for the rapid growth of this market.

Wood wastes include a large spectrum of wood products from primary and secondary processing such as bark, slabs, sawdust, chips, planer shavings, sander dust, end trims, used or scrapped pallets, and construction wood wastes. However, wood wastes also include logs, branches, and brush from urban tree removals and land clearing for construction, farming and industrial projects. Nowadays wood should be principal source of biomass. This wood is transformed into chips in order to increase automatic operations and to decrease the technical effort needed at the energy conversion plant.

For examples, wood chips are used in power plants, in CHP-plants, in biogas stations, in large heating plants and in small combustion units. Wood chipping serves many purposes such as upgrading waste forest wood, decreasing the production cost of renewable energy, promoting the development of unproblematic supply chain from technical and economic viewpoint and giving possibilities to automate the operation in the end use technology. Trees damaged by storms, harvesting residues and wood from thinning or pruning represent the main sources of the raw material for chipping. There are three different devices which can produce wood chips: the cone-screw wood chunker, the drum chipper and the disc chipper. In this paper basic properties and methods for producing wood chips, are presented.

Keywords: wood chips, production, location, chipping equipment



46

THE SUPPLY OF HEAT ENERGY FOR SMALLER URBAN UNITS OBTAINED FROM

RENEWABLE ENERGY SOURCES

Maja N. Marković; Ana A. Berket Bakota; Milena S. Jovanović;

Branislav V. Stojanović; Jelena N. Janevski

Abstract. Growing need for use of renewable energy sources in Serbia is caused by the price of fossil fuels and the constant decrease of their resources.

So far researches indicate that somewhere about one quarter of produced biomass can be used for energy production, without bigger impact on the structure of the soil.

Since Niš doesn’t have enough sunny days, energy of Sun is not a reliable source for this region. This applies also for the energy of the Wind, hydro potential and geothermal energy. Based on everything mentioned above, it can be said that in Niš and its narrow surrounding best solution is use of biomass as alternative energy source.

This paper presents analysis for one smaller urban settlement Čalije (part of Niš). This settlement presents suitable location for analysis of biomass implementation for the needs of heating and hot water preparation, during winter and summer. This small area is consisted of approximately 250 residential units, with average of 100 sq.metters area each. Analysis is done for four member households in each residential area.

Keywords: energy, biomass, energy savings, urban settlement, mini power plants.



47

BIOMASS DISTRICT HEATING SYSTEMS AND CONTROL STRATEGIES

Marko G. Ignjatović, Bratislav D. Blagojević, Dejan M. Mitrović, Mirko M. Stojiljković

Abstract. Biomass district heating systems are widely spread in Scandinavian countries, Austria, Canada, and UK etc. Since, there is tendency in Serbia to reduce GHG emissions through implementation of state of the art technologies in energy consuming sector, especially in municipal energy systems and to reduce emissions from individual households, biomass district heating systems could be proven as a good starting point to do so. The objective of this paper is to identify some of the biomass district heating system concepts as well as control strategies for central heating plant with the focus on biomass boiler. Three most widely used concepts have been identified: biomass boiler with buffer tank, biomass boiler with thermal storage and well known boiler cascade. Main characteristics of operation have been described for each of these concepts. Also two biomass boiler control strategies were described. The conclusion is that an in-depth analysis for various operating parameters of central heating plant with one or several boilers of known capacity and buffer tank/thermal storage sizing for a settlement of finite size and thermal load should be performed and presented to decision makers, especially in parts of Serbia where biomass potential is sufficient for operation of biomass district heating facility.

Keywords: biomass, district heating, biomass boiler control



48

POSSIBILITIES OF USING BIOMASS IN THE

SLAUGHTER-HOUSE INDUSTRY FOR HEAT PRODUCTION

D. V. Dakić, B. S. Repić, A. M. Erić, D. M. Đurović, M. R. Mladenović

Abstract. Slaughter-house industry is a major consumer of thermal energy used in the elaboration of the initial and final materials. Now for the heat producing mainly use liquid and gaseous fuels. Biomass, which represents the largest renewable energy source in Serbia, can be successfully used for this purpose, especially in places that have significant potential of biomass. The possibility of using agricultural biomass to produce thermal energy at a local abattoir was considered. Analyzed the various aspects of biomass uses: operating regimes, changes for heat demand in summer and winter period, and others. All consumers of thermal energy, which is led by hot-heated water, are circulating in a closed circuit, so it does not provide for water losses. Because of the technological cycle, which is uneven in terms of hot water, and the heating, the construction of the heat reservoir is planning. The construction of the reservoir is avoided oversize boiler, and his frequent switching on and off. It is anticipated that the primary fuel in the boiler house being baled biomass, the remains of crop production. As the remains may appear cereal straw, remnants of soybean and rapeseed or corn. Bales are cylindrical dimensions Φ ≈ (135-145) cm, L ≈ 135 cm.

Keywords: Biomass; slaughter-house industry; production; technology



49

IMPACT OF THE NUMBER AND OF THE TYPES OF THE COVERS ON THE TOP HEAT LOSS

OF A SOLAR WATER HEATER FLAT PLATE COLLECTOR

Velimir P. Stefanović, Andrijana D. Stojanović, Saša R. Pavlović, Predrag Živković

Abstract. Solar water heating systems are often viable to replace electricity and fossil fuels used for many home applications and therefore contribute to a sustainable energy future. Flat plate solar collector thermal performances can be modelled according to complex functions of the meteorological data, of the operating conditions and of the design system. Since the meteorological conditions cannot be modified, the flat plate solar collector performance can be enhanced working either on the operations conditions or on the solar water heating system components. This paper analysis a set of experimental results for single and double glazed flat plate water collector with different combinations of transparent material as well as their effect on top heat loss. It has been also presented an approach to the model of heat transfer process as well as the thermal behaviour of a flat plate collector evaluating different cover configurations. The effect of the thickness of the single glass cover has been also discussed. The results show that increasing the thickness of the single glass cover, the steady heat flux decreases at both low and high temperature of the absorber. The general aim of this paper is to define the optimal water flow and of the optimal collector flat area in order to give a good compromise between the collector efficiency and the output water temperature

Keywords: collector efficiency; heat losses; transparent cover



50

POTENTIAL OF MUNICIPAL SOLID WASTE AS RENEWABLE ENERGY SOURCE:

CURRENT STATE IN SERBIA AND THE WORLD


Abstract. Municipal Solid Waste management represents one of the priority environmental problems in the world. In the Republic of Serbia, there is no systematic, organized, separated collecting, gathering and recycling of municipal solid waste. Within the context of European Union (EU) energy policy and sustainability in waste management, waste-to-energy incineration which recovers energy from discardeed municipal solid waste and produce electricity and/or steam for heating, is recognized as a renewable source of energy. This paper presents an overview of the waste-to-energy industry, discusses the major challenges in expanding WTE incineration in the world, namely, high capital and operational costs, equipment corrosion, air pollutant emissions, and fly ash disposal. A perspective on municipal solid waste as a renewable energy source is also presented. With the significant benefits of environmental quality, the reduction of greenhouse gas (GHG) emissions, and government policies and financial incentives as a renewable energy source, WTE incineration industry is expected to experience significant growth in the coming decade and make greater contribution to supplying renewable energy in the world.

Keywords: renewable energy; waste-to-energy; greenhouse gas reduction



51

ADVANTAGES AND DISADVANTAGES OF INNOVATIVE TECHNOLOGIES FOR THERMAL

TREATMENT OF MUNICIPAL SOLID WASTE


Abstract. The development of innovative technologies for energy recovery from municipal solid waste could contribute to the reduction of both environmental pollution and dependence on fossil fuels. The hierarchy of methodologies for dealing with municipal solid wastes consists of recycling and composting, combustion with energy recovery and landfilling. Thermal disposal, especially incineration and gasification are viable and proven alternative. Gasification is the main technologies for biomass conversion to energy and particularly suitable to treat industrial waste, but there are some problems with municipal solid wastes related to their heterogeneity. But mass-burn grate incineration is currently the dominating method because of its simplicity and relatively low capital cost, nevertheless its hazardous emissions and harmful process residues. The number of different uses of gas shows the flexibility of gasification and therefore allows it to be integrated with several industrial processes, as well as power generation systems. This paper describes the current state of gasification technologies and gives an overview of their characteristics based on their energy analysis. Novel and innovative technology approaches emphasising European developments are reviewed, and prospective in syngas use with particular attention to the different process cycles and environmental impacts of solid wastes gasification.

Keywords: incineration; gasification; energy analysis



52

MULTI-CRITERIA METHODS FOR RANKING POLYGENERATION SYSTEMS

BASED ON RENEWABLE ENERGY SOURCES

S. M. Savić, G. Lj. Janaćković, M. S. Stanković

Abstract. The decision making process for polygeneration systems selection is very complex, and it should be evaluated and compared by means of multi-criteria methods of analysis. The classical method for selection is usually based only on a single criterion analysis, and it is defined by thermal or economic criteria. This sometimes results in wrong solutions or solutions which are not optimal. In recent years, multi-criteria decision making has been recommended as a method of selecting strategies, policies and methods for polygeneration systems and selecting appropriate renewable energy sources. The construction and functioning of a polygeneration system should be evaluated from many aspects. These aspects are: technical, social, economic, and environmental. The complexity and a number of polygeneration system quality parameters require the use of analytic tools that can evaluate a problem in multiple dimensions, examine all these parameters in the same way, taking into account different views of stakeholders which are included in decision making process. The paper presents methods for ranking elements (performances, indicators) while selecting polygeneration systems, as well as selecting appropriate renewable energy sources used in polygeneration systems

Keywords: polygeneration systems, performance indicators, multi criteria ranking, renewable energy sources



53

EFFICIENT USE OF WIND ENERGY USING WIND TURBINES WITH CVT DRIVE TRAIN

Vukašin Pavlović, Miloš Miloševic, Nenad D. Pavlović, Milan Pavlović, Nataša Jovanović

Abstract. Fossil fuels are, at the moment, the basic source of energy on the planet. However, constant increase of demand for energy lead to the point where energy gained from fossil fuels is no longer enough. Furthermore, burning fossil fuels releases toxic gases in form of carbon monoxide, carbon dioxide, sulfur monoxide and others, which have a negative impact on the environment. With all that in mind, there is obvious need for renewable sources of energy, which will participate in overall energy production and in the same time help preserve the environment. One of the possibilities for making this kind of energy is using the wind power, that is to say building a wind turbine. Today’s wind turbines with classic gear power transmission have a problem, in form of unavailability to regulate frequency number of generator’s rotor revolution in optimal interval. This paper presents a new approach to renewable energy, with special emphasis on optimal use of wind turbines using CVT drive train for efficient utilization of wind energy.

Keywords: fossil fuels, renewable energy, wind energy, wind turbine, CVT drive train



54

PRODUCTION OF PELLETS AND THEIR USE FOR HEATING PURPOSES

Mladen Stojiljković, Mirjana Laković, Branislav Stojanović, Jelena Janevski, Dejan Mitrović

Abstract. By the year 2020, greenhouse gas emissions should be reduced by 20 percent, renewable energy sources should represent 20 percent of Europe’s final energy consumption and energy efficiency should increase by 20 percent. There are also a number of major uncertainties and misperceptions in the debate regarding biomass energy, for instance regarding its sustainability, cost competitiveness, logistical viability, availability, and its potential impact on food and feed production. However, biomass can be good substitute for conventional fuels in heating systems for both residential and industrial buildings.

Biomass is a promising option for providing locally produced, renewable energy in Serbia. With 55% of its territory being arable land, and 25% under forests, Serbia has high biomass potentials. While it is not unusual for homes in the state to be heated with firewood, other forms of biomass fuel are not as common and commercial-scale use of biomass fuel is very limited.

This paper focuses on biomass in the form of pellets for heating purposes. A pellets physical characteristic, equipment for their production and combustion is described, with special regard to advantages and disadvantages of the pellets use for heating

Keywords: renewable energy, biomass, pellets, production, combustion, heating



55

THE USE OF AQUIFERS AS SEASONAL THERMAL STORAGE RESERVOIRS

Miloš Banjac, Mirjana Laković

Abstract. For several decades, aquifers have represented common heat sources for Ground Source Heat Pumps - GSHP. Such a method of groundwater use, its abstraction and re-injection in the ground after thermal exploitation (cooling), results in the creation of cold temperature fields in the ground – a cold "thermal plume". At the same time, for the sustainability of GSHP systems, it is possible, with additional solar energy collected during the summer period and its accumulation in those same aquifers, to annul this phenomenon. Moreover, if significantly greater amounts of heat are accumulated, it is possible to form a so-called - thermal storage reservoir. Since the efficiency of GSHP systems directly depends on the temperature of the heat source - aquifers, controlled formation and maintenance of the anthropogenic geothermal resource, can significantly increase the energy efficiency of the entire GSHP system. In this paper is presented state of the art of mathematical modeling of temperature fields in the groundwater layers and fields of underground water flows, which occur at work GSHP and highlight the main shortcomings of existing models.



56

POTENTIALS AND POSSIBILITIES OF USING WOOD BIOMASS IN SERBIA

Jelena N. Janevski, Branislav V. Stojanović, Mirjana S. Laković, Mirko M. Stojiljković

Abstract. Biomass is a renewable energy source that can be used as substitute for fossil fuels in the production of heat. The current condition of renewable energy source in Serbia is bed although Serbia has good potential for development. The potential of forest biomass as another important resource of biomass in Serbia lies in the processing of 1,5 million cubic meters of forest growth per year in the form of segments, chips and sawdust.

Wood biomass is currently the most exploited energy. The primary purpose of this work is to show the potential and possibilities of wood biomass in Serbia, which is important for further development of the renewable energy sector. The tendency in our country with developed wood industry is to use wood refuse for energy purposes. The most frequently used wood biomass is in shape of briquettes, pellets and wood chips. Production of wood pellets in Serbia is constantly growing, but not fast enough, and the technology has been developed that provides better burning in the boilers. Despite the potential, wood still has a low position in energy needs.

Keywords: biomass, wood, potentional, energy, development

5. Fluid Flow and Heat and Mass Transfer



58

THERMOECONOMIC MODELING OF A SIMPLE HEAT PUMP CYCLE:

AN ALTERNATIVE APPROACH FOR VALVE ISOLATION

A. B. Lourenço, J. J. Santos, J. L. Donatelli

Abstract. In any energy system, in the same manner that there are productive components, there also exist dissipative components. One of the thermoeconomic methodologies challenges is to define the productive structure of thermal systems that allows allocating rationally the cost of the dissipative components to the final products. Although there has been an advance in the development of thermoeconomic criteria for dissipative components allocation, this problem is still open. The introduction of the negentropy in thermoeconomics represented a great advance, since this magnitude allows quantifying the condenser product, which was not possible before because the condenser is a dissipative component, whose product cannot be expressed in terms of exergy only. However this magnitude does not allow defining the product of the valves. To overcome this limitation, this paper present a new approach based on disaggregation of physical exergy into, internal energy (U-U0), flow work (pV-p0V0) and the here called syntropy (T0S- T0S0), by applying it to a simple heat pump cycle to obtain the unit cost of the internal flows. The results show that this methodology is consistent, because the product-fuel ratio of each component of the structure is less than one for irreversible processes and this ratio will be equal to one for the reversible ones.

Keywords: Thermoeconomic Modeling, Exergy Disaggregation, Valve Isolation, Exergetic Cost



59

THERMAL BIOMASS CONVERSION INTO SYNGAS

V. V. Kosov , V. A. Sinelshchikov, V. M. Zaichenko

Abstract. Methods of gas fuel production as a result of biomass thermal processing are considered. The experimental data on composition and quantity of the gaseous products formed in the processes of pyrolysis of wood, peat and agriculture waste at various operating conditions are presented. It is offered to increase the conversion degree of initial raw materials into gas at the expense of thermal processing of liquid pyrolysis products. The method consists in filtration of gases and vapor formed during pyrolysis of initial raw materials through the porous carbon bed supported at a fixed temperature Tf. As the carbon filter the char obtained as a result of carbonization of initial raw materials was used. It was shown that as a result of thermal processing of the mentioned kinds of raw materials and the subsequent cracking of emanating volatile products over a charcoal at the temperature Tf = 10000С it is possible to receive about 1.4 m3 of synthesis gas with calorific value at level 11 MJ/m3 per one kg of initial raw material

Keywords: pyrolysis, biomass, synthesis gas



60

ONE DIMENSIONAL MODEL OF COOLING WATER IN COUNTERFLOW COOLING TOWER

Dušan Golubović, Dušica Golubović

Abstract. The basic characteristics of evaporated cooling water were presented in this paper. The film flow of water in the filling of counterflow cooling tower was analyzed. The equations of conservation of mass end energy for water and air were presented. The model was applied for cooling water in the hyperbolic cooling tower. For specific technical data, the basic dimensions of cooling tower silhouete of film type filling were established. The cooling water curve of diferent parameters of air were presented.

Keywords: Counterflow cooling tower, dimensional model



61

INFLUENCE OF VOLUME INITIALIZATION IN LARGE EDDY SIMULATION OF

TURBULENT COMBUSTION INSIDE CLOSED VESSEL

L. Perković, M. Tomić, N. Duić

Abstract. The intensity of turbulent combustion inside the closed vessel is mainly determined by level of turbulence persisting prior to the combustion. The first objective of this work is to introduce new algorithm for turbulence volume initialization within Large Eddy Simulation (LES) framework. The second objective of this work is to capture flame propagation, and consequently pressure-raise function, with reasonable accuracy w.r.t. the experimental results by means of computational fluid dynamics for different levels of initial turbulence. New algorithm for volume initialization directly employs vortices in a divergence-free way. The approach for turbulence – flame interacion is Coherent Flame Model within Large Eddy Simulation framework (CFMLES). Results are showing that turbulence initialization procedure proposed in this work is able to reconstruct the turbulence field given by the experiment. On the other hand, by proper initialization of turbulence the flame propagation and pressure raise function are matching the experiment results.

Keywords: Turbulent premixed combustion, turbulent flame speed, closed vessel, combustion bomb



62

THERMAL INSTABILITY IN PERTURBED POISEUILLE FLOW IN PRESENCE OF TIME

VARYING TEMPERATURE DIFFERENCE BETWEEN THE WALLS

Milos M. Jovanovic, Jelena D. Nikodijevic

Abstract. We consider Poiseuille-Rayleigh-Bénard flow which is directly numerical simulated by a two-dimensional pseudospectral method. This flow is subjected to longitudinal pressure gradient in horizontal rectangular channel which is heated from below and cooled from above. A temperature perturbation is used as initial disturbed source for the basic parallel flows. We consider the Poiseuille flow which is perturbed by tempreture field formed between two parallel horizontal plates with constant temperature at one wall and time varying temperature at the other. The whole spatio-temporal evolution is exhibited in this simulation.

For Re>0, the transition from Poiseuille flow in a cellular flow is obtained for values of Ra that are above the critical ones. Beyond this critical values the conductive state becomes unstable and the thermoconvective structures appear. The flow changes in a number of counter rotating vortices which move in direction of flow under the influence of streamwise (favorable) pressure gradient. The simulation has been carried out for two different Prandtl numbers, Pr=0.71 and Pr=7.

The pseudospectral technique is based on trigonometric polynomials as basis functions and Galerkin method in homogeneous direction (paralel to the plates of channel) and Chebyshev polynomials and collocation method in nonhomogeneous direction (normal to the plates of channel). The momentum equation is in the form of vorticity-streamfunction, and the problem of two boundary conditions for streamfunction and none for vorticity is circumvented by using the influence matrix method, to obtain the unkown boundary conditions for vorticity. For time discretisation semi-implicit Adams-Bashworth method has been used. The temperature, velocity and vorticity fields, which are induced by means of Poiseuille motion and free convection currents fields, are shown. The effect of different parameters like Rayleigh, Reynolds and Prandtl number and time are discussed

Keywords: Thermal instability, direct numerical simulation, Poiseuille-Raylaigh-Benard flow, time varying temperature difference, Rayleigh number



63

CHARACTERISTICS OF COMBUSTION CHAMBER FOR

COMBUSTION OF PELLETS AND WOODCHIPS

Branislav Stojanović, Jelena Janevski, Mladen Stojiljković, Dejan Mitrović

Abstract. Objective of this paper is to define main characteristics of combustion chamber for combustion of pellets and woodchips taking into account their specificities. First, specificities of biomass combustion are analyzed, with special focus on wood chips. Fuel humidity content, temperature and time of combustion is taken into account. Based on stoichiometrics for combustion and kinetics of combustion, necessary quantity of air for combustion process is determined as well as the air flow into the chamber and mixing fuel and air. Existing combustion chamber constructions are analyzed, for both small and large capacity boilers. Based on these constructions, basic flows of fuel and air within the chamber are defined. As the result, concept of combustion chamber for pellets and chips for boilers with capacity greater than 500 kW is given. Also, all necessary operating parameters needed for reliable combustion chamber operation are given.

Keywords: combustion chamber, combustion, pellet, woodchips



64

VERTICAL TEMPERATURE PROFILE IN THE INSTALLATION FOR THE COMBUSTION OF

WASTE FUELS IN THE FLUIDIZED BED FURNACE

Milica R. Mladenović, Dragoljub V. Dakić, Stevan Đ. Nemoda, Rastko V. Mladenović,

Aleksandar M. Erić, Milijana Paprika, Mirko S. Komatina

Abstract. This paper is a contribution to the investigation of combustion of waste liquid and solid fuels. Waste liquid fuels include sediment from crude fuel oil tanks or used edible/mineral oils, the disposal of which is most often linked to environmental issues. In addition, these substances, due to high ballast content, non-uniform composition and density, can not be burnt in conventional combustors, hence the technology of thermal disintegration in the fluidized bed (FB) imposes as a solution, which enables the combustion of fuels of most distinct types and non-uniform compositions. Waste solid fuels refer to coals from off-balance reserves (fine-grained, with high ballast and sulfur contents and low heating values) which should be used more rationally, implying the application of the FB combustion (FBC) as well. The fact that FB boilers can burn fuels with 85% of inert materials, with effective retention of SO2 by adding limestone into the furnace, and with lower NOx emissions, gives FBC significant advantages, compared to other combustion technologies.

Description of the experimental FBC facility is given, as well as experimental results, with the focus on the furnace temperature distribution, in order to determine the location of the intensive combustion zone as a function of fuel properties.

Keywords: liquid fuels, lowgrade coals, fluidized bed



65

INFLUENCE OF THE ALTITUDE ON EVAPORATION RATE OF COOLING WATER

AT NATURAL DRAUGHT COOLING TOWER

Vladimir I. Mijakovski, Vangelče B. Mitrevski, Nikola I. Mijakovski

Abstract. Natural draught cooling towers used at large power generating facilities during their operation are greatly influenced by local weather conditions, mainly temperature and humidity of the air. Another parameter that influences the operation of cooling towers is altitude of the power plant. Altitude has direct influence on the absolute humidity of the air and on the barometric pressure at certain location. Natural draught cooling tower of Thermo Power Plant (TPP) – Bitola, largest electricity producer in the Republic of Macedonia is taken as a reference and influence of the altitude on the evaporation rate of cooling water at the tower is given by a numerical example for three locations-cities in the Republic of Macedonia: Skopje with 245 meters altitude above sea level (asl), Bitola (615 meters asl) and Kruševo (1200 meters asl)

Keywords: altitude, cooling tower, evaporation rate



66

MHD DYNAMIC AND DIFFUSION BOUNDARY LAYER FLOW OF VARIABLE

ELECTRICAL CONDUCTIVITY FLUID PAST A CIRCULAR CILYNDER

A. Boričić, Ž. Stamenković, B. Boričić

Abstract. This paper concerns with unsteady two-dimensional dynamic and diffusion magnetohydrodynamic (MHD) laminar boundary layer of incompressible fluid past a horizontal circular cylinder. It is assumed that induction of outer magnetic field is function of longitudinal coordinate with force lines perpendicular to the body surface on which boundary layer forms. Outer electric field is neglected and magnetic Reynolds number is significantly lower then i.e. considered problem is in induction-less approximation. Variable electrical conductivity of the fluid is assumed as linear function of concentration. The developed governing boundary layer equations and associated boundary conditions are converted into a non-dimensional form using a suitable similarity transformation. Non-dimensional system of equations is solved using the finite difference method and iteration method. Numerical results are obtained and presented for incompressible fluid for different parameters such Sc and N number. The solutions for the flow and diffusion transfer and other integral characteristics, boundary layer, are evaluated numerical for difference values the magnetic field. Transient effects of velocity and diffusion are analyzed.

Keywords: MHD, dynamic, diffusion, boundary layer, circular cylinder

6. Examination of Operating Plants and

Experimental Examination of Plants



68

POSSIBILITY OF IMPROVING MAINTENANCE PROCESS IN HEATING PLANTS

Peđa Milosavljević, Dragoljub Živković, Dragan Milčić

Abstract. In today’s market, it is only those companies which are capable of permanent and quick adaptation to the conditions which change at a high rate that survive. In order for an company to remain competitive and maintain maximal efficiency of its plants, an approach different from the traditional maintenance concept is required. The classic approach to the maintenance process does not render maximal efficiency of plants, being based on the technological degree of the use of plants. Therefore, the man-plant environment must be fully taken into account, which renders high availability and performance of plants, which are then in their optimal state. Maintenance related to a process includes adequate maintenance measures, which are needed for a stable process, pinpointing the weak spots and their elimination, and permanent improvement of plants with respect to their management and maintenance. In order to achieve this goal, one must observe the complete lifetime of plants, starting with their design, building, installation, and use, until they are changed or abandoned. The paper includes examples of several improved maintenance processes in heating plant. The processes will be described according to the SIPOC (Supplier-Input-Process-Output-Consumer) model. Models of improved maintenance processes will also be given.

Keywords: energy efficiency, process, improvement, maintenance, plant



69

EXPERIMENTAL DETERMINATION AND COMPARISON OF HEAT PERFORMANCES OF

THREE FLAT COLLECTORS AND A CPC-2V CONCENTRATING COLLECTOR WITH A

SMALL CONCENTRATION RATIO

Velimir P. Stefanović, Saša R. Pavlović, Andrijana D. Stojanović,

Marko V. Mančić, Milan Lj. Đorđević

Abstract. Solar energy may be practically utilized directly through transformation into heat, electrical or chemical energy. Furthermore, it may be utilized for heating water for residential buildings, household and office space heating, as well as in some industrial processes. Solar systems referred as mid temperature (100 – 400 oC) are considered suitable for integration with industrial processes, cooling and polygeneration systems through use of concentrating solar collectors. The purpose of this paper is to not just to gain new theoretical knowledge via experimental and theoretical research of the CPC-2V concentrating collector, but also to gain experimental data relevant in the field of heat transfer in mid temperature and low temperature solar collectors, thus distinguishing the possibilities for improving efficiency of the mentioned collectors by parallel analysis of heating efficiencies between mid temperature and low temperature collectors.

The measuring results are presented as instantaneous heating efficiency as a function of reduced temperature. In this manner, it is possible to compare heating efficiency of the concentrating CPC collector with small concentrating ratio (CR=1.38) with sun traction control system and a stationary flat plate collector.

Keywords: Flat plate Collector, Efficiency, CPC collector, solar energy



70

EFFECT OF CARBON DIOXIDE CONTENT IN NATURAL GAS ON

EMISSIONS AT LEAN PREMIXED CONDITIONS

Marija Živković, Miroljub Adžić, Aleksandar Milivojević, Vuk Adžić, Vasko Fotev

Abstract. This paper presents an analysis of the influence of the carbon dioxide content in natural gas on nitrogen oxides and carbon monoxide emissions at lean premixed conditions. Natural gas used, was with different content of CO2 (10, 20, 30 and 40%). Experimental investigation of NOx and CO emissions of a purposely designed micro turbine gas burner with pilot burner is presented. Both burners are equipped with swirlers. Mixtures of air and fuel are introduced separately: through inner swirler primary mixture for pilot burner, and through outer swirler secondary mixture for the main burner. Effects of variations of carbon dioxide content in natural gas were investigated, including parametric variations of the thermal power and air coefficient

Keywords: carbondioxide content, emissions, swirl burner



71

THE IMPACT OF LOAD OF TRANSMISSION LINES AND TRANSFORMERS ON POWER

SYSTEM GENERATION

Ljiljana M. Samardžić, Vladan D. Krsman

Abstract. This paper deals with the problems of Security analysis of transmission network of power system. There is implemented the application for detection of overloaded branches and calculation of sensitivity coefficients of branch current per every generation power in the network. After calculation of these coefficients, the next step is the analysis of retrieved values. The calculation of sensitivity coefficients is done after base case power flow which is executed after base case state estimation. The next steps are to check of results and to obtain how is possible to use these results efficiently in real time to correct generators limits. There are monitored changes of state variables and values of sensitivity coefficients. Phase measurements, which are part of base case state estimation, have no significant influence in calculation. As it is expected, the main influence on calculation comes from topology change, branch overloads, and nodes elimination as consequence of power flow algorithm. After analysis of retrieved results, there is concluded that results are stable and usable for correction of generators limits, as preventive action. Basically, this application provides an interface between transmission network and power generation, in power system. Every operator, five minutes cyclically, has information about branch overloads and preventive action. Preventive action can be increase or decrease power generation. Also, information can be “keep generation – no preventive action”. From the other side, operator has efficient monitoring of overloaded branches and their influence on generation.

Keywords: sensitivity analysis, security analysis, state estimation, power flow, transmission network, interface transmission network and power plant



72

THE INFORMATION SYSTEM OF REPORTING AND MONITORING PROCESSES IN A

POWER PLANT HEATING PLANT NOVI SAD

Slobodan Stevanović, Sladjana Barjaktarović, Nebojša Kaljević, Tatjana Karadjinović,

Abstract. Production Monitoring sub module implemented in Panonske thermal power plants as part of ERP System is mainly designed to monitor hour-to-hour production progress. Also, it supports an organization in tracking production, daily, weekly and/or monthly, as well as in planning resources and further on, it offers a possibility to achieve the optimal utilization of all available resources.

Keywords: information system, reporting, monitoring, cogeneration, electrical and thermal energy, energy efficiency.



73

PARTICULATE MATTER EMISSION INVESTIGATION ON THE UPGRADED

ELECROSTATIC PRECIPITATORS AT TPP ''NIKOLA TESLA''

Milić Erić, Predrag Škobalj, Zoran Marković, Dejan Cvetinović,

Rastko Jovanović, Predrag Stefanović

Abstract. Electric Power Industry of Serbia have to coordinate their operation in compliance with EU requirements related on the limitation of emissions of certain pollutants into the air from large combustion plants up to 2016. Among other measures, the reconstructions of the electrostatic precipitators on the residue units was planned until 2015.

Long term plan of environmental modernization for Economic Assosiation ''TPP Nikola Tesla'' has been prepared in year 2002. Priority is given to reduction of emission of particulate matters – fly ash from the stacks as sources of pollution.

The reduction of the outlet concentration of particulate matter was achieved by increasing of height and number of collecting electrodes, adding one additional field of electrodes and enhancement of current and voltage characteristics of electrostatic precipitator sections.

This paper presents outlet concentration of particulate matter results of the guaranteed investigations for the reconstructed electrostatic precipitators. Manufacturers of electrostatic precipitators guaranteed the outlet concentration of particulate matter in the highest amount of 50 mg/Nm3.

All tests were performed by Institute of Nuclear Sciences Vinča, Laboratory for Thermal Engineering and Energy, in accordance with standards ISO 9096 and EN 13284-1.

Keywords: particulate matter, emission, electrostatic precipitator, reconstruction, modernization



74

MATHEMATICAL MODELLING AND EXPERIMENTAL INVESTIGATION

OF THE FURNACE FOR STRAW COMBUSTION

D. Djurovic, S. Nemoda, D. Dakic, A. Eric, B. Repic

Abstract. As one of the most easily accessible renewable energy resources, straw can be burned to provide heat energy. In this paper, results of theoretical and experimental research conducted under the proceedings of mathematical - numerical modeling of turbulent reacting flows has been presented. Two-dimensional turbulent flow model with homogeneous chemical reactions has been developed. The proposed model has been analyzed on the example of adiabatic combustion chamber for combustion of agricultural biomass. Turbulent flow is considered using time averaging Navier-Stokes equations that are closed by k-ε turbulence model. Calculations based on the proposed models were conducted using commercial CFD package FLUENT 6.3.26. For the purposes of experimental research, measurements of fluid flow and thermal parameters, such as continuous measurement of temperature in different points in the workspace furnace, air flow, flue gas flow, continual analysis of combustion products as well as setting heat and material balance, were carried out. Comparative analysis of the results of experiments and calculations indicate satisfactory agreement between the model and experiment.

Keywords: biomass, mathematical modelling, k-ε model, experimental investigation



75

VARIATION OF OPERATION OF LOW-PRESSURE REVERSIBLE AXIAL FAN DRIVEN

BY INDUCTION MOTOR FROM START TO THE STEADY-STATE

Živan Spasić, Božidar Bogdanović, Milan Radić

Abstract. Operating characteristics of a fan are determined by experimental tests on test stands, for the constant speed and for certain density of air. In experimental studies, it is necessary to provide conditions of repeatability of results. This can be achieved only if we take the impact of all relevant factors into account.

We investigated the reversible low-pressure axial fan, outer diameter of impeller De=630 mm, hub diameter Di=300mm, which is directly set to the induction motor with nominal power P=1,5 kW.

The paper considers changes of the fan speed, from start to the steady-state, the fan at a constant load, for different positions of the blades.

Experiments have shown that from the start to the steady-state regime speed of rotation decreases by 1%, decreasing the pressure in the ventilator for 2% and volumetric flow rate for 1%. The steady-state regime of investigated fan, or constant rotation speed at constant load, is achieved approximately after 60 minutes from starting.

The noted change is eplained by the increase of winding resistances of induction motor, due to heting.

Keywords: Axial Fan, Characteristic, Airflow, Induction Motor.

7. Energy Efficiency and Rational Energy Management



77

ENERGY EFFICIENCY OF TYPICAL SERBIAN RURAL HOUSES

D. M. Šumarac, M.N. Todorović, Z.B. Perović, R. D. Roglić

Abstract. According to European Directives (EPBD 2002 and EPBD 2010-Recast) all member states are obliged to introduce Passport of energy efficiency (here after will be referred to as Passport of EE) for houses. Without Passport of EE new buildings cannot obtain permission for usage, while already existing buildings cannot be sold or rented. Serbia already adopted new regulations, based on the Low of planning and construction (official gazette No. 61/2011). Regulations predict the use of Passport of EE in Serbia too, and it is predicted that in Serbia there is 3.5 million of residential units (houses and apartments). For rural houses there are no special requirements in EPBD directives. If they are used occasionally then there is no need for Passport of EE to be issued. However in this study it is shown that considerable savings can be achieved if the houses are properly repaired according to the principles of energy efficiency.

In this paper, rural house in the mountainous region of Serbia, which was built in the beginning of 20th century, is analyzed. Only traditional materials for construction and primitive technology without heat insulation were used. Taking into account the fact that analyzed house is typical for Serbian mountainous region, the results and conclusions obtained herein can be extended to other rural houses of this type in this region. Besides that rural house, built in Vojvodina is analyzed. On both houses measurements of temperature, humidity and dew point are performed. Based on this measurements and calculations of needed energy for heating it is show that both houses are inefficient and considerable retrofitting are necessary to decrease it.

Keywords: energy efficiency, rural house, mountainous hose, Vojvodina house



78

THE DIFFERENT ENERGY SOURCE TYPE INFLUENCE ON

BUILDING PRIMARY ENERGY NEEDS

M. N. Todorović, T. S. Bajc

Abstract. The paper deals with the influence of different energy sources types on primary energy needs of a residential-business building with a total usable area of 1300m2, which is located in Belgrade. The annual final energy consumption of the building, including energy for heating, cooling, ventilation, lighting and domestic hot water preparation, is calculated. The total energy needs of the building are calculated and compared for different energy sources. The impact of the applied energy source on primary energy needs is valuated. Different energy sources types, which are compared are as follows: district heating system that generates heat from fossil fuels, individual gas boiler for the building, local air conditioning units, heat pump, and solar heating systems for domestic hot water preparation, and furthermore their influence on primary energy needs of the building. The final energy consumption is calculated in accordance with International and European standards EN ISO 1379, EN 15316 and EN 15193. The energy savings that can be achieved by appropriate selection of energy source and the optimal system operating regime are analyzed.

Keywords: primary energy needs, annual energy consumption, energy source type, energy savings, optimal working regime



79

A REVIEW OF BENCHMARKING AND RATING CONCEPTS WITHIN THE

FRAMEWORK OF BUILDING ENERGY CERTIFICATION SCHEMES

J. Skerlić, D. Gordić

Abstract. Energy certification schemes for buildings emerged in the early 1990s as an essential method for improving energy efficiency, minimising energy consumption and enabling greater transparency with regards to the use of energy in buildings. However, from the beginning their definition and implementation process were diffuse and, occasionally, have confused building sector stakeholders. A multiplicity of terms and concepts such as energy performance, energy efficiency, energy ratings, benchmarking, labelling, etc., have emerged with sometimes overlapping meanings. This has frequently led to misleading interpretations by regulatory bodies, energy agencies and final consumers.

This paper analyses the origin and the historic development of energy certification schemes in buildings along with the definition and scope of a building energy certificate and critical aspects of its implementation. Embodied energy calculations and life cycle analysis are pointed out as key elements in building energy assessment and should be included in energy regulation and certification schemes in order to effectively lead the building sector towards sustainability.

Keywords: energy certification, energy rating, energy benchmarking, embodied energy, building life cycle



80

FORECASTING ENERGY CONSUMPTION IN RESIDENTIAL HOUSE DURING HEATING

PERIOD USING FEED-FORWARD NEURAL NETWORKS

Vesna Ranković, Dragan Cvetković, Ilija Nikolić, Nenad Miloradović, Milorad Bojić

Abstract. The objective of this study is to develop a feedforward neural network (FNN) to predict the energy consumption during the heating period inside a small residential building.

The two-layer FNN with the Levenberg–Marquardt learning was constructed. A database was generated using the simulation by EnergyPlus software. The FNN structure was designed and trained by using the MATLAB Neural Network Toolbox.

The input variables analyzed in this paper are the following: the temperature of the heating water from the gas boiler, the thermal comfort temperature in the zone and the ventilation air change per hour. The optimal FNN architecture was determined. The FNN predicted values are in accordance with the values obtained by the simulation of the total energy consumption in the building. The performance of the FNN was assessed through the correlation coefficient (r), mean absolute error (MAE) and mean square error (MSE). This FNN can be used as an alternative numerical methodology, thus saving the computational time and reducing the cost of studies

Keywords: Feedforward Neural network, Energy consumption, EnergyPlus, Building heating



81

EFFICIENT CONTROL OF UNIVERSITY AUDITORIUIM HEATING SYSTEM

Saša Jovanović, Milan Matijević, Milan Ristanović, Dragan Lazić

Abstract. Automatization for measurement and control of an intermittent heating system applied to an auditorium at Faculty of Mechanical Engineering in Kragujevac is presented in this paper. The technical solution based on KNX/EIB standard is described. The technical characteristics of a controlled system, data acquisition, heating regimes, components of the system, visualization and testing have been presented. The described system has been exploited in the function of every day needs and energy efficiency. Measurement results, data and costs analysis for 14 days periods during winter season were done for controlled and non controlled heating system, with almost identical outside (i.e. weather) conditions and auditorium occupation. It has been shown that a controlled system significantly reduces energy consumption compared to a non controlled system.

Keywords: heating system, automatic control, consumption



82

COOLING BUILDING BY GEOTHERMAL ENERGY: APPLICATION IN SOUTH ALGERIA

Sehli Abdelkrim , Tamali Mohamed, Hasni Abdelhafid

Abstract. In this study we are interested in the refreshment by the geothermal science, the technique which is not very exploited until now in our country. This technique, called Canadian’s well, uses air/ground heat exchanger system. In this study a numerical analysis of the phenomenon through the modeling and the simulation of the performances of this system are carried out. The question is to know the air temperature evolution at the output of the exchanger. The temperature at the inlet of the heat exchanger tends throughout the exchanger to the ground temperature and its value depends on many parameters.

Keywords: Renewables energy- Refresh - air to ground heat Exchanger - Geothermal.



83

APPLICATION OF ENERGY EFFICIENCY AND BIOCLIMATIC PRINCIPLES

IN URBAN PLANNING

Biljana Rakić, Ljiljana Mihajlović

Abstract. Concepts of urban planning based on energy principles imply more rational and efficient energy wise cities than the ones we live in today. Planning at any level needs to have a human, ecological and energy efficient component and currently not many cities have that.

Usage of structural landscape and the structure of singular buildings have a large influence on the rational consumption of energy. Careful design of buildings, settlements and urban structures can significantly contribute to energy savings, provided that the appropriate, multidisciplinary studies are conducted. When we speak of energy efficiency in planning and application, there are several levels that need to be mentioned:

• Energy efficiency in spatial, regional and urban plans, • Energy efficiency in building design, • Energy efficiency in building and exploitation, etc.

The energy efficient building design implies not only energy optimization, but comfort optimization as well. If these measures of rational energy consumption are to be applied to new buildings, 2% more should be saved annually than in the old buildings. This is why it is important to invest into adaption and reconstruction of existing building fund as well.

Bioclimatic houses, apart from energy saving, create a more balanced relationship between human and his surroundings. As stated, bioclimatic elements in planning and design significantly lower the usage of conventional energy. Bioclimatic design is not a new style or direction in the buildings trends of XX century. This concept takes into consideration the global method of solving the basic question of human existence, the habitat. Integration of house with its surrounding and natural energy flows, their usage for comfort without misbalance in the environment, are some of the goals of bioclimatic design. Bioclimatic is a concept of design and facilitation in a building aiming to become an integral part of the environment.

Buildings represent around 50% of the overall energy consumption. It is possible to implement principles of bioclimatic planning and design with exploitation of renewable energy sources (RES) to improve the efficiency and lower the overall energy consumption for residential purposes (heating and cooling, lighting, water heating, etc.) It is necessary to define basic principles which would allow the broader application of new, energy efficient, methods, especially in urban environments.

Keywords: energy efficiency, bioclimatic principles, urban planning, renewable energy sources, public participation



84

DUOBLE SKIN FAÇADES – DEFINITION AND CONCEPT,

HISTORICAL DEVELOPMENT, ADVANTAGES AND DISADVATANGES

Aleksandar S. Anđelković, Damir D. Đaković

Abstract. Concept of double skin façades (DSF) for offices and commercial buildings was first established in Europe. Through continuous evolution and development, it became an important and rising architectural element of buildings all around the world. In Serbia, there aren’t many examples of the buildings with double skin façades, but considering energy efficiency and other benefits, this concept (DSF) should become more popular in future.

From a building physics point of view, double skin façades are very complex; optical and thermal comfort, heating losses during winter, cooling loads in summertime, ventilation, acoustics, moisture, and fire safety requires careful investigation at the design stage. This text, as start of my PhD thesis, presents review of current situation in a field of integrated building design – concept of double skin façades. Historical development, classification, advantages and disadvantages are presented in this paper. Also, plans and recommendations for the future work are presented.

Keywords: double skin façades, definition, concept



85

COMPRESSED AIR SYSTEM STRUCTURE AND ENERGY EFFICIENCY

D. D. Šešlija, I. M. Ignjatović, S. M. Dudić

Abstract. Compressed air systems represent significant consumer of electric energy in contemporary industrial systems. Average value is about 10 % of overall energy consumption in industry. Unlike the electrical energy, compressed air is produced and consumed at the same place, inside the production facility. It is, therefore, very important to take care about the energy efficiency of this systems. In this paper is given an overview of the influence of compressed air system structure on the energy efficiency of this system as well as on the production system itself. Following possibilities are identified and discussed: Dissection of the system in smaller systems that are separately controlled (remotely controlled shut-off valves with possibility of disconnecting from main supply when production is not operating); Separate level of pressure in some segments with lower or higher level than in the main system; Position of discharging valve, etc. Some experimental measurements are given in order to obtain more clear view of the significance of appropriate structuring of compressed air system.

Keywords: Compressed Air System Structure, Energy Efficiency



86

COMPARATIVE REVIEW OF THE ENERGY EFFICIENCY OF THERMAL POWER PLANTS

WITH THE OPEN AND CLOSED-CYCLE COOLING SYSTEM

Mirjana Laković, Slobodan Laković, Miloš Banjac, Mladen Stojiljković

Abstract. Energy efficiency of thermal power plants depends on many factors, but the influence of parameters of atmospheric air on the energy efficiency, in terms of achieving maximum power and minimum specific heat consumption was neglected in the design of the capacity, and in their exploitation.

In this paper, the influence of parameters of atmospheric air on the operation of thermal power plants is analysed, for the plant that have once-through (or open-cycle) cooling system, and also for the plant with closed-cycle cooling system with wet cooling towers. Plants certainly show the same trend of decrease in energy efficiency by increasing the temperature of atmospheric air in the summer. Thereby changing the efficiency of power plants with once-through cooling system is related to the mean temperature of the natural water which is using for removal of waste heat in the condenser, while the plant with the closed-cycle system is exposed to a daily change of water temperature in the cooling tower, and thus the daily change of the energy efficiency.

Power plants which are using wet cooling towers for cooling condenser cooling water usually have higher design temperature of cooling water, thus the designed condensing pressure is higher compared to plants with once-through cooling system. Daily and seasonal changes further deteriorate energy efficiency of these plants, so it can be concluded that these plants have up to 5% less efficiency compared to systems with once-through cooling.

Keywords: power plant, cooling water, armospheric air, energy efficiency



87

TECHNO - ECONOMIC ANALYSIS OF THE POSSIBILITY OF COMBINED HEAT AND

POWER GENERATION IN DISTRICT HEATING PLANT "ERDOGLIJA" KRAGUJEVAC

Vladimir Vukašinović, Milun Babić, Dušan Gordić, Dubravka Jelić, Davor Končalović

Abstract. Combined production of thermal and mechanical (electrical) energy, in most cases, has greater efficiency than separate production of heat and electricity. Implementation of cogeneration units in the existing plants was significantly stimulated in the European countries. Techno-economic analysis of combined heat and power is carried out based on several criteria. Analysis of the heating plant that uses a natural gas as primary fuel and oil fuel as a reserve fuel is presented in this paper. Installed power of three hot-water boiler plant is 40.15 MW. A comparative analysis of using gas turbines and gas engines and selection of the optimal solution is also presented in this paper. Comparative analysis was performed according to the criteria of total power, fuel consumption, gas temperature, overall efficiency and total annual fund savings.

Keywords: cogeneration, gas turbine, gas engine, efficiency



88

DESIGN OF SYSTEM FOR CENTRAL ASPIRATION OF WOOD DUST

Vladimir Vukašinović, Dušan Gorgić, Milun Babić

Abstract. A major prerequisite for the efficient operation of machineries in furniture industry is properly designed system for dust removal and collection. Inadequate dusting directly affects the life cycle of cutting tools, as well as the lubrication system, because inadequate removal of waste material from the cutting tool is cause for insufficient heat dissipation. In addition, proper design of aspiration ensures limited emissions of particles into the atmosphere, as well as dusting of a production hall. A large amount of dust in the production hall, which has accumulated on heat exchangers, significantly reduces the efficiency of heating systems. Installation of central aspiration system provides a lot of benefits, among other things, the place to collect waste. Waste material can be used for energy purposes, and that can leads to significant savings. The model of replacing the existing system of aspiration with a central one with appropriate techno-economic analysis is presented in this paper.

Keywords: aspiration, dusting, wood industry, pellet production, energy saving



89

PROPER SELECTION AND USE OF THE HOUSEHOLD APPLIANCES

AS A WAY OF THE ELECTRICAL ENERGY SAVINGS

D. Adamović, N. Lukić, Z. Đorđević, V. Marjanović, S. Jovanović

Abstract. High consumption of the electrical energy in households is result of the growing number of electrical appliances in the home and use electricity for heating and lighting. Age of household appliances in houses in Serbia shows possibilities of significant savings of the electrical energy by using appliances of the next-generation. Today, household appliances have a mark of the energy efficiency class, which indicates to the consumers a future cost of electricity. It is often that declared consumption may differ from the real one. Conditions of use, selected programs and incoming technical parameters affect this. Generally, electricity consumption in households depends on the dynamics and way of use, type and number of appliances, their age and class of energy efficiency.

In this paper it will be shown how to reduce energy consumption by proper selection and use of the household appliances. There will also be an overview of the energy efficiency of these devices and the cost of buying more expensive and more efficient devices, in conditions of the prices ratio in Serbia.

Keywords: household appliances, energy efficiency class, cost of more efficient devices



90

APPLICATION OF AHP AND QFD METHOD IN THE ANALYSIS OF ENERGY EFFICIENCY

Slađana Živadinović, Ivan Savić

Abstract. In addition to planning, organizing, leadership and control decision making is one of the basic management processes.

In this project, much attention is devoted to just making decisions and determining the weights using the AHP method in order to achieve the maximum degree of utilization of energy and energy efficiency.

The higher the value of weights follows that the decision maker attaches more importance to a given criterion, and thus determines the priorities in achieving energy efficiency policies.

Keywords: decision making, energy efficiency, AHP method



91

A STRATEGIC APPROACH TO ENERGY AND ENVIRONMENTAL MANAGEMENT

Sladjana Živadinovic, Marija Milicevic, Nada Živanovic

Abstract. Energy management represents integral part of the strategic management approach of the organization. Ecologic audit represents a way to control organizations outcomes trough which we can compare gained results with the set goals. Ecologically responsible organizations plan and ran their own processes respecting the fundamentals of the sustainable development.

Environment management cannot be treated separately from quality management. It is organizational obligation to involve activities for environment protection control as well as control of implemented activities (in agreement of activities defined by ISO 14000 series of standards)

Keywords: strategy, energy, management, environmental



92

STUDY OF USAGE OF RECYCLED RUBBER CRUMBS (RRC) FOR PRODUCTION OF

THERMAL INSULATION PANELS

Petar Đekić, Anica Milošević, Boban Cvetanović

Abstract. One of the greatest problems of the modern consumer society is the production of waste and its disposal. Current measures that are based on landfilling and incineration have not provided good results, therefore the process of waste recycling is gaining more ground every day. Special attention is being paid to production of ecological products with sustainable development in mind. The process of recycling is not economically worthwhile, thus a number of countries in the world offer financial help to rubber recycling centers, which has recently become the case in our country also. The products made from recycled rubber crumbs are very good sound and thermal insulators, they can be used as roof and floor thermal insulation in buildings and houses. Physical and mechanical properties (fire-retard, breaking strength, heat conductivity, and the heat conductivity coefficient) panels made of crumbs particle size from 0,1 to 3 mm are examined in this paper

Keywords: Recycled rubber, testing, insulation properties



93

INDUSTRIAL WASTE HEAT TO COVER DOMESTIC HEAT DEMAND -

ANALYZING POTENTIAL AND DEMAND

S. Brückner, H. Schäfers, I. Peters

Abstract. Domestic heat holds a large share of energy consumption in European household and therefore also represents a large CO2 saving potential. The idea of the presented work is to use excess heat form industrial production units in the cities and use it to supply the neighboring houses with heat. Therefore the heat demand in the investigated area in Hamburg was estimated based on building age, area and volume and virtually equipped with a statistical heating system. The potential of industrial waste heat was estimated through data collection of the major companies and data from the chamber of crafts combined with waste heat data for different sectors and estimated production rates. To account for different temperature levels of the waste heat (30-1500°C) and the domestic heat demand (40-130°C) a pinch analysis is used. First results show that a lowering of the heat demand temperature by switching radiators to panel heating is mandatory to be able to use the excess heat in the investigated area of Hamburg. As a next step renewable resources (geothermal heat etc.) are considered as additional heat sources.

Keywords: industrial waste heat, domestic heat, pinch analysis, energetic potential



94

EVALUATION OF THERMAL AND ELECTRICAL ENERGY CONSUMPTIONS

IN SCHOOLS OF ČAČAK REGION

S. M. Dragićević, S. M. Stojković , S. G. Vasović

Abstract. School buildings are most numerous typology objects and big energy consumers that should be supplied continuously with species quality. As school buildings usually have great potential for improving energy efficiency they are a promising location for addressing energy savings. This paper presents an energy analysis of the school buildings in Čačak region. On sample of eleven primary schools and four high schools follow data were gathered and analyzed: annual consumption of thermal and electrical energy, volume and floor area of buildings, surface of facade and windows, number of students, number of classrooms, type and year of building of the object and type of insulation material used. In order to analyze energy consumption and proposals of measures for energy efficiency of school buildings on the territory of Čačak, energy specific consumption indexes per unit floor area, per student and per classroom of thermal and electrical energy have been calculated. The obtained results identify schools, which need measures for energy efficiency improvement.

Keywords: energy consumption, school, energy specific consumption index



95

REVIEW OF THE CURRENT ENERGY POLICY IN THE REPUBLIC OF SERBIA

WITH THE DEVELOPMENT PERSPECTIVES

Mirjana Laković, Branislav Stojanović, Mladen Stojiljković, Marko Ignjatović

Abstract. The Republic of Serbia in its early stage of development is trying to harmonize its legislation to acording Europian Union legislation, and also to synchronize its progress with experience of other countries from the field of sustainable development in the field of energy and energy efficiency. Serbia is a country which largely depends on import of all forms of energy, which to a great extent affects its economic stability. On the other hand, Serbia has very high unused potential in improvement of energy efficiency in both, energy consumption and energy production sector, as well as great renewable energy potential, which can cover almost half of its primary energy needs.

In this paper the basics of Serbian energy policy, current energy supply and energy demand statistics, the possibilities and limitations of energy sector are described. Special attention is devoted to renewable energy sources potentials and possibilities for their exploatation.

Keywords: Energy Law, Development Strategy, Renewable Energy Sources



96

THE ROLE OF THE INTELLIGENT BUILDING SKIN IN

INCREASING ENERGY EFFICIENCY IN BUILDINGS

Milica Stojanović, Nataša Petković

Abstract. In the past few decades more and more attention is being paid to energy conservation issues. In building design it can be achieved through increased energy efficiency. In order to achieve this goal the concept of 'intelligent buildings' has been introduced. The conventional paradigm of ’inteligent buildings’ relates to the use of more or less complex building management system, which provides a building with motorized actions. The development of the intelligent skin, which is part of a wider program of the intelligent buildings, is related to its responsive performance, sometimes but not always in relation to the energy performance of the whole building, and can be compared with the biological idea of intelligence and response. Through applying the intelligent building envelope, the need for additional heating and cooling, and other systems can be minimized or avoided completely. This paper, based on energy requirements, discusses the concept of intelligent skin in the context of their solar control, ventilation, heating and cooling buildings.

Keywords: intelligent skin, energy efficiency, adaptive façade



97

ESTIMATION OF ENERGETIC CHARACTERISTICS OF

SETTLEMENTS IN NIŠ REGION, SERBIA

Branislav V. Stojanović, Mirko M. Stojiljković, Marko G. Ignjatović,

Goran D. Vučković, Mladen M. Stojiljković, Jelena N. Janevski

Abstract. Estimation of energetic characteristics of settlements is of great importance when sustainable energy systems are planned, when energy efficiency and renewable energy projects are identified and estimated, but also for short term energy supply planning. Sometimes annual or monthly energy consumption estimation for some standard, average or predicted weather conditions is enough, but there are cases when it is necessary to collect data related to hourly demand profiles.

Here, approach for estimating energy characteristics of buildings based on annual or monthly energy consumption data in terms of primary energy is presented. The approach is based on the classification of objects. Hourly energy demands for some characteristic days are also given as an example.

Keywords: Energy consumption, Settlements, Primary energy, Demand profiles

8. Energy and Environmental Aspects of Transportation



100

NEW WORLD-WIDE LIGHT-DUTY TEST CYCLE

Stojan Petrović, Velimir Petrović

Abstract. Vehicle manufacturer sells their products all around the world. However, it is economically inefficient to prepare substantially the same model in different versions in order to meet different emission regulations and methods of measuring emissions for different world regions. Therefore, UN Economic Commission for Europe (ECE) gave a task to its World Forum for Harmonization of Vehicle Regulation (WP.29) to create harmonized procedures for vehicle emission certification. The work on development of world-wide procedures for emission certification of heavy duty vehicles and non-road mobile machinery is already finished and corresponding Global Technical Regulations (GTR) concerning new harmonized world driving cycles, their performances and measurement methodologies are accepted. However, the development of world-wide light-duty test procedure (WLTP) is still at the beginning though the work on it started three years ago and it is expected to be finished by the end of 2013. On its 62nd session (at this year July meeting), Working Party on Pollution and energy (GRPE/ECE/UN) accepted first version of global transient test cycle for passenger cars and light duty commercial vehicles. This paper presents information on the development of world-wide light-duty test cycle (WLTC) which will be part of WLTP GTR. The presentation involves introduction on discussed problem, purpose of new procedure with participating countries, formation of driving cycle from collected data on driving conditions around the world, and proposed first version of new transient driving cycle which has four driving modes: low, middle, high and extra-high. Proposal of this driving cycle is still under discussion.



101

ONE APPROACH FOR IMPROVEMENT OF SPARK IGNITION ENGINE EFFICIENCY

Jovan Ž. Dorić, Zoran M. Čepić, Ivan J. Klinar

Abstract. The possibilities that enable the improvement of a spark ignition engine fuel economy has been analysed. In this paper was presented simulation of engine performance in case when unconventional piston motion law was used. Main aim of this new piston motion is the realization of combustion during constant volume. With this unconventional piston movement more complete expansion in engine`s cylinder was also achieved. The analysis has been performed numerically, using engine cycle computer simulation software Ricardo/WAVE. New four stroke cycle that was presented with this study is characterized by higher power, volumetric and thermal efficiency than the standard four stroke cycle. The results obtained in this paper may provide guidance for the design of practical internal combustion engines.

Keywords: IC engine, efficiency, constant volume combustion



102

HYDRAULIC HYBRID TECHNOLOGY REVIEW – PERSPECTIVES AND BENEFITS OF ITS

IMPLEMENTATION ON PUBLIC TRANSPORTATION VEHICLES

M. Kitanović, S. J. Popović, N. Miljić, M. Cvetić, M. Tomić , P. Mrđa

Abstract. IC engines amount to 25% in global energy consumption, which is mostly due to their massive share in road transport of approximately 99%. The motivation for development of fuel efficient vehicle propulsion systems arises from strong dependence of the transportation sector on fossil fuels and the need for a rapid response to the global warming challenge. Hybridization has, globally, proven its capabilities in enhancing the powertrain efficiency and is the only technology offering significant breakthroughs in near and mid-term. While there are a number of approaches, Hydraulic Hybrid Technology (HHT) has been lately utilized as an alternative power source for vehicles. HHT gives unique advantages for easy and cost-effective implementation in current production vehicles as well as an aftermarket solution. It seems to be the replacement for expensive, bulky and environmentally hazardous battery technology. Hydraulic energy conversion and storage provide exceptional power density and efficiency making them ideally suited for regenerative powertrain design. It is particularly efficient in city traffic conditions, characterized by frequent stops, coasting and long idling periods. Additionally, emissions are reduced, particularly at idling and low speeds, compared to conventionally powered vehicles. While HHT is still in the prototype and simulation stage, this paper reviews current state-of-the-art.

Keywords: IC Engine, Hydraulic Hybrid, regenerative powertrain, fuel consumption, emission



103

THE EFFECT OF BIODIESEL AND BLENDED DIESEL FUEL ON EXHAUST EMISSIONS

R. Gligorijević, J. Jevtić, Đ. Borak

Abstract. Exploitation of the natural reserves of petroleum products and emission reduction has put a tremendous onus on the automotive industry.

Diesel engines are the most efficient prime movers. Hence, diesel is being used extensively, but due to gradual depletion of fossil fuel reserves, its price keep changing, and the impact of environmental pollution of increasing exhaust emission there is an urgent need for suitable alternative fuels.

Uasge of vegetable oils poses some challenge like poor spray penetration,valve sticking and clogging of injector nozzles. Most of these problems may be solved by partial substitution of diesel with vegetable oil.

From this aspect this work deal with the effect of biodiesel and blended diesel fuel on exhaust emissions diesel engine



104

ECOLOGICAL AND ENERGETIC DIESEL ENGINE CHARACTERISTICS WITH BIODIESEL

Aleksandar Lj. Davinić, Radivoje B. Pešić, Stevan P. Veinović, Stojan V. Petrović

Abstract. Bio fuels are often considered as a renewable fuel and neutral in terms of CO2 emissions. In spite of the desires of researchers to find new fuels, engines and vehicle technologies, it should be known that there are no "clean" vehicles, or "clean" energies, or "fully renewable" fuels. According to our knowledge, there is no correct scientific definition of the meaning of the word “renewable” – existing meanings contain very small differences. Technically, all energy sources are renewable, but in different time intervals. The correct use of the term "renewable" fuels is pointed in the first part of the paper, while the results of own experimental research on the engine fuelled with biodiesel and diesel fuel are presented in another part of the paper.

Keywords: biodiesel, ecological characteristics, energy characteristics, IC engine



105

THE COMBUSTION CHAMBER APPRAISAL ON THE BASIS OF ITS

FLUID FLOW CHARACTERISTICS

Zoran S. Jovanović, Zlatomir M. Živanović, Željko B. Šakota, Zoran M. Masonicic

Abstract. In this paper some results concerning the comparison of 3D fluid flow patterns in combustion chambers with entirely different bowl-in-piston shapes such as ”omega” and “cylinder” were presented. Both combustion chambers were with flat head, vertical valves and identical elevation of intake and exhaust ports. All results were obtained by dint of multidimensional modeling of nonreactive fluid flow in arbitrary geometry with moving objects and boundaries. The fluid flow pattern during induction and compression in both cases was extremely complicated and entirely three-dimensional. Some differences due to geometry of the bowl were observed only in the vicinity of TDC. In the case of “omega” bowl all three types of organized macro flows were observed while in the case of “cylinder” bowl no circumferential velocity was registered at all. In the case of “cylinder” bowl the reverse tumble center of rotation shifting from exhaust valve zone to intake valve zone during induction stroke and vice-verse from intake valve zone to exhaust valve zone during compression were observed while in the case of “omega” bowl no such a displacement was legible. During expansion and exhaust the fluid flow pattern is entirely invariant as regards the geometry of the bowl.



106

USAGE OF SMALLER VEHICLES IN URBAN ENVIRONMENT

IN ORDER TO DECREASE CO2 EMISSIONS

V. Momčilović, A. Manojlović, D. Vujanović, S. Bunčić, V. Papić

Abstract. Passenger cars entering an enclosed and heavily polluted (therefore “endangered”) urban zone are to be charged increasingly based on their “weight inefficiency”. The authors came up with a solution to impose restrictions and sort of access charging (weight-based) to private cars in order to decrease the number of environmentally inefficient SUVs and larger passenger cars, whose share have importantly grown in the last decade or so. Their energy efficiency is a direct result of the realized transport volumes (transported tare- and brute-weight) likewise their CO2 emissions. The objective is to minimize vehicles’ weight to be able also to lower their engine power and therefore their CO2 emissions. Those bigger, weight- and CO2-inefficient vehicles are often circulating in the critical urban zones where their environmental impact represents an important issue. Therefore, one of the viable and recommended long-term solutions for the developing countries is to somehow influence citizens’ purchasing habits toward smaller and fuel efficient (but safe) - “weight efficient” cars with lesser pollutant emission, permitting with a green label open access to all “critical” urban zones exempt of such access charging.

Keywords: small vehicle, urban environment, weight efficiency, CO2 emissions



107

AUTOMOTIVE MECHATRONIC SYSTEMS – ECONOMY AND ECOLOGY

Milan Pavlović, Miloš Milošević, Dušan Stamenković, Aleksandar Stefanović, Vukašin Pavlović

Abstract. Mechatronics is multidisciplinary field of engineering. Mechatronic system design deals with the integrated and optimal design of a physical system, including sensors, actuators, electronic components, and the embedded digital control system. These systems have micro to macro application, and one of them is application in motorcars. As we know, constantly reducing fossil fuels and lower fuel consumption in motorcars are top problems in world. Moreover, combustion of fossil fuels releases harmful gases (carbon – dioxide, carbon – monoxide, nitrogen oxides, etc.) which contribute to the global warming and destroying an environment. Mechatronics can affect on solving these problems. Because of that, today, mechatronic systems have become a required system in all vehicles, from basic systems to comfort. In this paper are shown mechatronic systems in spark-ignition and diesel engines which has a goal to reduce fuel consumption and pollutants in exhaust gases

Keywords: Mechatronic systems, automotive engineering, environment protection, fuel consumption, pollutants in exhaust gases

9. Technologies and Plants



110

ENERGY EFFICIENCY IMPROVING OF COMBINED CYCLE GAS POWER PLANTS

(CCGPP) AND ENVIRONMENT BENEFITS WITH TRIGENERATION AND

TRIGENERATION POWER PLANTS (TPP) USED

Marijan Gacevski

Abstract. Energy efficiency indicators of CCGPP and TPP and environment indicators by Thermal Power Plant (ThPP) use are given in the paper.

Analyzes over comparison of the presenting results will refer in way of ability proving by implementation and upgrading of trigeneration systems in CCGPP. Although analyzes and investigations of environmental indicators and how these indicators shows positive environment affects by TPP using in comparison by other conventional ThPP.

On base on all made analyzes and investigations which will belong on this kind of plants and systems adequate conclusions, refers and future directions would be defined.

Keywords: trigeneration plants, trigeneration systems, energy efficiency indicators, environmental indicators



111

THE ANALYSIS A CALCULATION OF WAVED EXPANSION JOINT

Jelena Nikolić, Aleksandar Petrović , Aleksandra Đerić

Abstract. This study shows the different methodological procedures related to calculation and design of wave expansion joints of circular cross section. Calculation of wave expansion joints according to relevant standards is presented in this paper. Analysis of terms according to relevant SRPS standards and EN standards is also shown in the paper. As a special part of the paper, examples of wave expansion joints application in different exploitation conditions are calculated.

Keywords: wave expansion joints, design, calculations, strength



112

EFFICIENCY ASSESSMENT OF DIFFERENT CAB AIR DISTRIBUTION SYSTEM LAYOUTS

Dragan Ružić, Ferenc Časnji, Aleksandar Poznić

Abstract. Conditions inside the cab are important factor for operator's performance, therefore for total efficiency and safety of operator-tractor-environment system. Cab ergonomic is prerequisite in ensuring the optimal working performance of the system, where the human could easily become the weakest link in the agricultural working process.

Hot environmental conditions during the summer agricultural works are especially unfavourable, since there is a large amount of heat entering the cab, mostly due to solar radiation. Despite of applied heat rejection methods, the stream of the air flow from ventilation outlets is the only active method for cooling an operator's body in a ventilated and air-conditioned tractor cab. Two main layouts of the air distribution systems present in modern tractor cabs are analyzed, the system with outlets located on ceiling and the system with outlets located on instrument panel.

The aim of the study is to compare local thermal effects on operator's body between different designs of air distribution, under the same mass flow rate of equal air temperature. For this purpose, the virtual model of the middle-sized tractor cab with operator was made, and efficiency is assessed by comparison of dry heat loss from the human body segments, which is related with human thermal sensation. The analysis was done by computational fluid dynamics, using published experimental and other data for verification purposes. The results show that differences in segmental dry heat transfer for different air distribution layouts have an influence on an operator's thermal sensation and comfort, under the same cab thermal conditions.

Keywords: tractor cab, ergonomic, microclimate, air distribution, thermal sensation



113

HOW TO DETERMINE WHEN DRYING INTERVALS

START AND FINISH DURING GRAIN DRYING

Damir D. Đaković, Aleksandar S. Anđelković

Abstract. Some possibilities for determination of start and end point for drying interval during grain drying are shown in the paper. Two graphic ways of determination of drying periods are widely accepted. However, there are several different ways not previously used for determination of these intervals, such as values obtained during calculation of effective moisture diffusivity, some exergetic parameters and even uncertainty analysis. Some results are shown in this paper according to the results of corn drying and analyses conducted. Comparative analyses among different parameters are shown.

Keywords: drying interval, effective moisture diffusivity, exergy, uncertainty



114

COMBINED HEAT AND POWER TECHNOLOGIES - AN OVERVIEW

Dejan Mitrović, Dragoljub Živković, Velimir Stefanović, Mirjana Laković-Paunović

Abstract. Thermal power plants are a major source of electricity supply in many developing countries. The conventional method of power generation and supply to the customer is wasteful in the sense that about a quarter of the primary energy fed into the power plant is actually made available to the user in the form of electricity. The major source of loss in the conversion process is the heat rejected to the surrounding water or air due to the inherent constraints of the different thermodynamic cycles employed in power generation. Moreover, users may be far from the point of generation, which results in additional transmission and distribution losses in the network. The concept of cogeneration is based on the principle of thermal cascading which consists of generating power on site where a substantial fraction of waste heat produced is recovered to satisfy the heating demand of the end-user. There is thus a considerable enhancement of the overall conversion efficiency. There are essentially four types of group’s cogeneration plants for heat and power. These are plants which are based on the technology of steam turbines (plant based on steam turbines with back pressure, or plant-based condensing steam turbine), then plants based on gas turbines (whether derived from the heat recovery gas output from gas turbines, whether used for heat and electricity with combined cycle) plant to produce heat and power on the basis of the internal combustion engine (Otto or Diesel-petrol engines) or on an external combustion engine (Stirling engine) and alternative and innovative concepts CHP plants.

In this paper overview of cogeneration technologies based on according to the sequence of energy use and in accord with the technology, is presented.

Keywords: Cogeneration, cogeneration technology



115

ROTATING STALL IN CENTRIFUGAL PUMP RADIAL IMPELLERS

Ž. M. Stamenković, J. B. Bogdanović-Jovanović

Abstract. The design of hydraulic turbomachines has reached the stage where improvements can only be achieved through a detailed understanding of the internal flow. The prediction of the flow in such equipment is very complicated due to the rotation and the curved three-dimensional shape of the impellers. Furthermore, the flow in turbomachines shows unsteady behavior, especially at off-design conditions. Considering these complexities, computer simulations is becomeing increasingly important. With the objective of gaining improved insight in the local flow behavior and increasing the accuracy of numerical simulations, the flow field in a centrifugal pump impeller has been investigated using DES in order to analyze rotating stall formation and development. Obtained results are compared with other author’s experimental and numerical results, showing satisfactory agreement.

Keywords: centrifugal pump, rotating stall, radial impeller, CFD, DES



116

CONVENTIONAL AND ADVANCED EXERGETIC ANALYSES

APPLIED TO AN INDUSTRIAL PLANT

Goran Vučković, Gradimir Ilić, Mića Vukić, Mirko M. Stojiljković

Abstract. Exergetic analysis is an universal method for evaluating the rational use of energy. It can be applied to any kind of energy conversion system or chemical process. An exergy analysis identifies the location, the magnitude and the causes of thermodynamic inefficiencies and enhances understanding of the energy conversion processes in complex systems. Conventional exergetic analyses pinpoint components and processes with high irreversibility. The total exergy destruction occurring in a component is not only due exclusively to the component but is also caused by the inefficiencies of the remaining system components. To overcome the limitations of the conventional analyses and to increase our knowledge about a plant, advanced exergy-based analyses have been developed. These analyses provide additional information about component interactions and reveal the real potential for improvement of each component constituting a system, as well as of the overall system. In this paper, an industrial plant is analyzed using both conventional and advanced exergetic analyses. Some of the exergy destruction in the plant components is unavoidable. This unavoidable part is constrained by internal technological, physical and economical limitations, i.e. each component's endogenous exergy destruction. Calculations related to the total avoidable exergy destruction caused by each component of the plant supplement the outcome of the conventional exergetic analysis.

Keywords: exergy, exergy destruction, conventional exergetic analysis, advanced exergetic analysis

10. Automatics, Process Control and Expert Systems



118

ABOUT THE DYNAMIC BEHAVIOR AND THE REGULATION OF

NEW TYPE OF WIND TURBINE GEARBOX BASED ON CVT

Boban Andjelković, Dragan Milčić, Jelena Stefanović Marinović, Aca Micić, Biljana Djordjević

Abstract. The published research of the future of energy indicate the importance of wind energy as energy source. Because of the difficulties related to the intermittent nature of wind power, automatic control must be applied. Random nature of wind requires the use of variable transmission ratio between the propeller and electrical power generator. To achieve this, a new concept of wind turbine power transmissions, anticipate differential power transmission and power transmitters with variable transmission ratio (CVT) has been developed within project TR14004. Only a part of the power is transmitted through CVT. In this paper the possibility for automatic control of such system due to its complex structure is presented. Implementation of classical controller for automatic control, due to the difficulty in determining its parameters, difficulty in determining the dynamic properties of structural elements and stochastic characteristics of wind, is uncertain.

The main objective of this paper is the analyze of the possibility and conditions of using automatic control on such system. The second objective is fuzzy reasoning in the process of automatic control analize.

Keywords: wind turbine, fuzzy reasoning, automatic control, simulation



119

SYSTEM MODERNIZATION OF THE STEAM BLOCK AUTOMATIC CONTROL USING DCS

AND SCADA SYSTEMS AND PLC CONTROLLERS

Milena Todorović, Dragoljub Živković

Abstract: In thermal power plant ''Nikola Tesla'' - A in Obrenovac old relay systems for regulation and control, on all 6 units, were replaced with new modern DCS systems. These systems enable on-line monitoring of operating parameters, their archiving and further processing according with the user’s needs. Since these systems contain the functional units for enthalpy calculation, required number of measurements was introduced and values were adopted for the non-measurable variables, the mathematical model was made for calculation of specific GROSS unit consumption and specific NET unit consumption. Considering this, continuous monitoring of each change of GROSS and NET efficiency was enabled.

Automatic generation control (AGC) system in power plants plays very important roll in controlling of electric power system. Electric power industry of Serbia (EPS) for the purpose of secondary load frequency control and active power used only hydro power plants so far. Looking up to electric power system of developed countries, Electric power industry of Serbia (EPS) started to create conditions to include steam blocks in secondary load frequency control and active power. Necessary condition for this is their modernization. In this paper, beside the review of the modern controlling system (PLC/SCADA system), it will be presented how steam block takes part in secondary load frequency control and active power of the electric power system, as well as one of the solution of simulation of the steam turbine operation.

Keywords: Regulation unit, Secondary load frequency control, DCS-Distributed Control System, SCADA - Supervisory Control And Data Acquisition, AGC - Automatic Generation Control, PLC - Programmable Logical Controller



120

INTELLIGENT CONTROL SYSTEMS FOR AUTONOMOUS

ENERGY COMPLEXES OF THE DISTRIBUTION POWER NETWORK

L. B. Director, I. L. Maikov

Abstract. The modern concept of energy based on the creation of active-adaptive networks, smart meters, multi-level control, distribution and consumption of energy, the use of digital technologies. The problem of developing of technology for smart grid autonomous power systems incorporating different energy sources and energy storages is no less urgent than the development of smart grid systems for the large-scale power. At the represented paper approaches to simulation of the energy complex and the control algorithms when operating in standalone mode, and as part of a local distribution network are presented. The optimal configuration of the energy complex and the value of nominal parameters of its elements are calculated with variable energy loads of the consumer and changes in external conditions (wind speed, solar radiation). As a criterion for optimizing the criterion of minimum cost of energy has been selected.

Keywords: smart grid, microgrid, autonomous power systems, distributed generation



121

DETECTION OF THE POSITION AND ESTIMATION OF DIMENSIONS OF THE MOVING

OBJECT IN THE LOW VISIBILITY CONDITIONS BY APPLYING THE TECHNIQUE OF

DIGITAL IMAGE PROCESSING

Aca Micić, Biljana Djordjević, Boban Andjelković, Dragan Radenković

Abstract. Flexible, real, mechatronical systems often use processes of automatic detection and estimation of the moving object in the low visibility conditions. It has been suggested in this work a sistem for improvement of the image quality along with the more precise estimation of the dimensions of the object, which can be easily implemented and which is suitable for working in the real world time under the unfavorable conditions, as well as in cases when the object is physically inaccessible. The system has been based on the fact that some regions might have increased local illumination and decreased local contrast as a consequence of decrease of light signal intensity. The improvement has been obtained by applying the inverse process, in other words, by increasing of the local contrast and decreasing of the local illumination. The process that has been suggested is being executed by applying of the modified techniques of the homomorphic filtering of the digital image. The system has been tested on an example of object with high level of symmetry and the results that have been achieved have been analyzed and presented.

Keywords: Measuring. Nonlinear enhancement of the contrast. Homomorphic filtering



122

A TRACEABLE RELATIVE HUMIDITY CALIBRATION IN THE INSTITUTE “VINČA“

N.D. Milošević, N.M. Stepanić

Abstract. The paper presents a method used in the Institute Vinča for a reliable and traceable relative humidity calibration in the temperature range from 5 to 50 °C. Inside a controlled temperature and humidity environment, supplied by a mixed-flow humidity generator, measurements of hygrometers under calibration (HUC) are compared with those of calibrated reference instruments. A traceability chain from temperature to reference relative humidity and next to HUCs is provided by using a chilled-mirror dew-point temperature system and precise relative humidity probes. Corresponding calibration uncertainties are analyzed, particularly those associated to temperature uniformity of controlled calibration environment. Two examples of relative humidity calibration with dew-point and relative humidity reference measurements in the range from 15 to 75 %RH and from 5 to 45 °C are presented and discussed.

Keywords: Dew-point temperature; Mixed-flow humidity generator; Relative humidity; Relative humidity calibration



123

LIQUID COOLING IMPLEMENTATION FOR DATACOM EQUIPMENT

Sevde Stavreva, Marko Serafimov

Abstract. Data centers are distinguished by especially high heat generation, which is highly concentrated, ununiformly distributed and variable. As the heat load density increases, thus increase the requirements for providing the prescribed working conditions, which in these centers are classified in for classes. Providing the working conditions in these centers is a challenging task. The heat load at the Datacom equipment ( computers, network equipment, electronic equipment etc. ) imposing the need for liquid cooling devices. This paper discusses the possibilities and ways of liquid cooling of Datacom equipment



124

EXPLOITATION RESEARCHES OF THE THERMO-ENERGETIC SYSTEM’S AVAILABILITY

Dragan Milčić, Dragan Kalaba, Dragoljub Živković, Miroslav Mijajlović

Abstract. Thermo-energetic system, consisting of boiler, steam turbine and three-phase synchronous generator, represents a major power plant component, so delays in the working process of such a systems directly cause delays in work of the power system, or furthermore of complete electro-energetic system of a country. This implies that power plants must have technical solutions that will work give maximum availability and reliability during the process of working. The paper presents the determination of availability and reliability of a thermo-energetic system based on exploitation researches.

Keywords: Thermo-energetic system , Reliability, Maintainability, Availability



125

CONTROL SYSTEMS FOR MICRO AND MINI HYDROPOWER PLANTS

Vladislav. A. Blagojević, Jasmina B. Bogdanović-Jovanović, Miodrag M. Stojiljković

Abstract. The need to reduce global energy consumption and make efficient use of energy resources is undisputed today and this has been an integral element of international contacts and agreements for many years now, especially from Kyoto Protocol to the United Nations Framework Convention on Climatic Change passed on 1997. Hydropower plants, especially micro and mini hydropower plants are nowadays the best example of such a strategy in many developed and developing countries. The main aim of this paper is the description of different micro and mini hydropower systems, with emphasis on the control systems used in their operation

Keywords: micro and mini hydropower plants, energy efficiency, turbine, control systems

PREDUZEĆE ZA PROIZVODNJU, INŽENJERING, UNUTRAŠNJU I SPOLJNU TRGOVINU

Tadeuša Košćuška 56 11000 Beograd Tel/fax: +381 11 6557 930; 6557 927

http:// www.viaocel.rs e-mail: [email protected] e-mail: [email protected]

Osnovna delatnost preduzeća VIA OCEL d.o.o. je inženjering termotehničkih i termoenergetskih postrojenja, što podrazumeva sve faze počev od izrade projektno tehničke dokumentacije, izvođenja radova pa do kasnijeg održavanja sistema, trgovina proizvodima crne i obojene metalurgije. U kratkom periodu VIA OCEL je zauzeo jednu od vodećih pozicija u ovim delatnostima i postao pouzdan partner zahvaljujući visokom kvalitetu svojih usluga.

NAJZNAČAJNIJE REFERENCE:

JKP BEOGRADSKE ELEKTRANE:

Modernizacija toplotnih podstanica za daljinsko grejanje, toplovodi i priključenja objekata,

rekonstrukcija toplane Konjarnik i Novi Beograd , izmenjivačka stanica TO Novi Beograd .

JP ELEKTROPRIVREDA SRBIJE - TE NIKOLA TESLA, OBRENOVAC:

Proizvodnja grejnih površina, isporuka elemenata za pregrejače

i međupregrejače, izrada i isporuka ekonomajzera , izrada i

isporuka ulaznih i izlaznih komora pregrejača pare, izrada i

isporuka parovoda, izrada i isporuka radnih kola mlina za

ugalj - N 400.42,kapaciteta 130t/h. TE KRAJOVA, RUMUNIJA Izrada i isporuka aksijalnih ventilatora dimnog gasa.

mailto:[email protected]

simterm 2011-book of abstracts

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