hidraulica.fluidas.rohidraulica.fluidas.ro/2014/nr3/hidraulica_magazine_no3-2014.pdf · - prof....

No. 3/2014

ISSN 1453 – 7303 “HIDRAULICA” (No. 3/2014) Magazine of Hydraulics, Pneumatics, Tribology, Ecology, Sensorics, Mechatronics

3

CONTENTS

• EDITORIAL Petrin DRUMEA

5 - 6

• THE EXPERIMENTAL VERIFICATION OF EFFECT OF LUBRICATION ON COEFFICIENT OF FRICTION IN ENDOPROSTHESIS OF HIP JOINT

Andrea HARINGOVÁ, Karol STRAČÁR, Karol PRIKKEL

7 - 12

• THE USE OF BIOCHAR AS A MEANS OF SOIL REGENERATION Sava ANGHEL, Alina Iolanda POPESCU

13 - 18

• ELECTRONIC SCREENING Justinian Laviniu CÎRSTEA, Dorel STOICA

19 - 24

• TILLER HYDROSTATIC TRANSMISSION Gheorghe IVAN, Radu CIUPERCA, Ioan GANEA

25 - 30

• RAINFALL INDICES IN THE CITY OF BUCHAREST Carmen Otilia RUSĂNESCU

31 - 35

• STUDY OF THE FLUIDIZED BED HYDRODYNAMICS FROM THE ENERGETIC BOILERS USING DIFFERENT TYPE OF SOLID PARTICLES

Daniela HOARĂ, Gheorghe LĂZĂROIU

36 - 45

• GENERAL METHODOLOGY OF WORKING WITH HVOF INTEGRATED TECHNOLOGICAL SYSTEM

Valeriu AVRAMESCU, Luminita Elena OLTEANU, Loredana Theodora PAUN, Raluca Magdalena NITA, Daniel BOBE, Sebastian ROSULESCU, Marius MANEA

46 - 51

• CABIN HEAT REMOVAL FROM PARKED CARS Adrian CIOCANEA, Dorin Laurentiu BURETEA

52 - 58

• INTEGRATED TECHNOLOGICAL SYSTEM FOR THERMAL SPRAYING BY HVOF PROCESS

Theodora Loredana PAUN, Valeriu AVRAMESCU, Raluca Magdalena NITA, Daniel BOBE, Sebastian ROSULESCU, Elena Luminita OLTEANU, Marius MANEA

59 - 65

• THE PROCEDURE FOR DRYING PLANT PRODUCTS IN CONVECTIVE DRYERS 66 - 71Iulian – Cezar GIRLEANU, Gabriela MATACHE


4

MANAGER OF PUBLICATION

- PhD. Eng.Petrin DRUMEA - Hydraulics and Pneumatics Research Institute in Bucharest, Romania

CHIEF EDITOR - PhD.Eng. Gabriela MATACHE - Hydraulics and Pneumatics Research Institute in Bucharest, Romania

EXECUTIVE EDITORS

- Valentin MIROIU - Hydraulics and Pneumatics Research Institute in Bucharest, Romania

- Ana-Maria POPESCU - Hydraulics and Pneumatics Research Institute in Bucharest, Romania

SPECIALIZED REVIEWERS - PhD. Eng. Heinrich THEISSEN – Scientific Director of Institute for Fluid Power Drives and Controls IFAS,

Aachen - Germany

- Prof. PhD. Eng. Henryk CHROSTOWSKI – Wroclaw University of Technology, Poland

- Prof. PhD. Eng. Pavel MACH – Czech Technical University in Prague, Czech Republic

- Prof. PhD. Eng.Alexandru MARIN – POLITEHNICA University of Bucharest, Romania

- Assoc.Prof. PhD. Eng. Constantin RANEA – POLITEHNICA University of Bucharest, Romania

- Lecturer PhD.Eng. Andrei DRUMEA – POLITEHNICA University of Bucharest, Romania

- PhD.Eng. Ion PIRNA - General Manager - National Institute Of Research - Development for Machines and

Installations Designed to Agriculture and Food Industry – INMA, Bucharest- Romania

- PhD.Eng. Gabriela MATACHE - Hydraulics & Pneumatics Research Institute in Bucharest, Romania

- Lecturer PhD.Eng. Lucian MARCU - Technical University of Cluj Napoca, ROMANIA

- PhD.Eng.Corneliu CRISTESCU - Hydraulics & Pneumatics Research Institute in Bucharest, Romania

- Prof.PhD.Eng. Dan OPRUTA - Technical University of Cluj Napoca, ROMANIA

Published by: Hydraulics & Pneumatics Research Institute, Bucharest-Romania Address: 14 Cuţitul de Argint, district 4, Bucharest, cod 040557, ROMANIA Phone: +40 21 336 39 90; +40 21 336 39 91 ; Fax:+40 21 337 30 40 ; E-mail: [email protected] Web: www.ihp.ro with support of: National Professional Association of Hydraulics and Pneumatics in Romania - FLUIDAS E-mail: [email protected] Web: www.fluidas.ro HIDRAULICA Magazine is indexed in the international databases:

HIDRAULICA Magazine is indexed in the Romanian Editorial Platform:

ISSN 1453 – 7303; ISSN – L 1453 – 7303


5

EDITORIAL DE CE HERVEX? In perioada 5-7 noiembrie 2014 se desfasoara la Calimanesti-Caciulata in judetul Valcea editia a 21-a a Conferintei si Expozitiei Internationale de Hidraulica si Pneumatica “HERVEX”.

Incepand cu anul 2013 organizatorilor traditionali (INOE 2000-IHP Bucuresti si CCIVL) li se alatura si o unitate de cercetare de prestigiu din Polonia (Institutul de Tehnologie Miniera – KOMAG din Gliwice), facand ca manifestarea sa se desfasoare alternativ in cele doua tari, in anii impari in Polonia sub numele de CYLINDER, iar in anii pari in Romania sub numele de HERVEX.

Dr.ing. Petrin DRUMEA DIRECTOR DE PUBLICATIE

Intrucat conferinta, probabil cea mai importanta din domeniul hidraulicii si pneumaticii din Romania, are in continuare rolul de platforma de prezentare a noutatilor, inovatiilor si tendintelor, ea reuseste sa adune foarte multi specialisti romani pentru un schimb direct de idei.

Inca de la inceput organizatorii romani si-au pus intrebarea privind rolul si utilitatea acestui simpozion. Initial HERVEX a avut un rol extrem de important in aducerea la aceeasi masa a producatorilor, a proiectantilor, a profesorilor si a utilizatorilor romani de hidraulica si pneumatica pentru a-si prezenta realizarile ultimilor ani. Astazi manifestarea, care intre timp a devenit internationala, include cateva activitati interesante, utile si de mare interes pentru specialistii domeniului.

Una dintre aceste actiuni este cea de a analiza si face unele recomandari profesorilor care pregatesc pe viitorii specialisti ai domeniului, atat la nivel universitar cat si la nivelul perfectionarii profesionale. Tot in acest sens, de mai multi ani se desfasoara un concurs tehnic pentru tinerii specialisti, fie studenti, fie proaspat absolventi.

O alta activitate de perspectiva o constituie contactul cu specialistii si profesorii de hidraulica si pneumatica din tari europene cu care Romania a stabilit legaturi si care prezinta realizarile lor recente si mai ales tendintele dezvoltarii domeniului.

In acest an se va dezbate noul program european Orizont 2020 si se vor analiza posibilitatile participarii in comun la realizarea unor proiecte de interes pentru tarile prezente la HERVEX 2014. Acest lucru este favorizat si de participarea unor IMM-uri de profil sau interesate de domeniu.

De mare interes a fost in ultimii ani si prezentarea unor echipamente complexe cu actionare hidraulica sau pneumatica utilizate in productia energiei, atat a celei clasice, dar mai ales a celei bazate pe resurse regenerabile si, de asemenea, implicarea in sistemele care reduc, recupereaza sau optimizeaza resursele si consumurile energetice.


6

EDITORIAL WHY HERVEX? From 5th to 7th of November 2014 in Valcea county, at Calimanesti Caciulata, will be organized the 21st edition of the International Conference and Exhibition of Hydraulics and Pneumatics “HERVEX”.

Since 2013 a prestigious research entity in Poland (KOMAG Institute of Mining Technology in Gliwice) joins the traditional organizers (INOE 2000-IHP Bucharest and CCIVL), determining the event to be held alternately in both countries, in odd years in Poland, referred to as CYLINDER, and in even years in Romania referred to as HERVEX.

Ph.D.Eng. Petrin DRUMEA MANAGER OF PUBLICATION

Since the conference, perhaps the most important in the field of hydraulics and pneumatics in Romania, continues to play the role of a platform for presenting news, innovations and trends, it manages to gather a lot of Romanian specialists for a direct exchange of ideas.

Since its inception Romanian organizers have asked themselves the question on the role and usefulness of this symposium. Originally HERVEX had a major role in gathering around the same table the Romanian producers, designers, teachers and users of Hydraulics and Pneumatics for them to present their achievements in recent years. Today the event, which has since become an international one, includes several interesting activities, useful and of great interest to the specialists in the field.

One of these activities is to analyze and make recommendations to professors who teach the future specialists in the field, both at university level and in professional training. In the same regard, for several editions there has been organized a technical contest for young professionals either students or newly graduates.

Another prospect activity is the contact with specialists and professors of Hydraulics and Pneumatics in European countries which Romania has established connections with, who come to present their recent achievements and especially the development trends in the field.

This year there will be discussed the new European Programme Horizon 2020 and will be explored the possibilities for joint participation in the implementation of projects of interest to the countries attending HERVEX 2014. This is encouraged by the participation of SMEs active in the field or interested in the field.

Of high interest there was in recent years also the presentation of complex equipment hydraulically or pneumatically actuated used in energy production, both classical, and especially the one based on renewable resources, and likewise the involvement in systems that reduce, recover and optimize energy resources and consumption.


7

THE EXPERIMENTAL VERIFICATION OF EFFECT OF LUBRICATION ON COEFFICIENT OF FRICTION IN ENDOPROSTHESIS OF HIP JOINT

Andrea HARINGOVÁ1, Karol STRAČÁR 2, Karol PRIKKEL 3

1 Institute of chemical and hydraulic machines and equipment, STU in Bratislava, Slovak republic, [email protected]



Abstract: The endoprosthesis of hip joint has overall lifetime up to 20 years. After this period the patient has to submit the revision operation. The main problem of the failure of endoprosthesis of hip joint are debris that comes from direct contact of head and socket pad and so called dry friction. The paper deals with effect of additional lubricant on the value of coefficient of friction in endoprosthesis of hip joint. As the testing fluid was selected the replacement of synovial fluid: solution of hyaluronic acid. Keywords: lubrication, coefficient of friction, endoprosthesis

1. Introduction

The endoprosthesis of hip joint is composed from 3 basic parts- stem with head and socket and has overall lifetime 20 years. The lifetime is limited by debris that are caused by direct contact of head and socket with absenting lubrication layer. The dry friction continuously reflects in mostly polyethylene debris coming from the socket cup. These polyethylene debris are very harmful for human body and causes infection and loosening of the endoprosthesis followed by the failure of endoprosthesis (fig. 1).

Fig.1 Failed components of endoprosthesis

According to the [5] 55% cases of failure of primary total hip joint endoprosthesis are caused by loosening of one of the components of the endoprosthesis. The amount of debris caused by dry friction is 100 - 200 μm/year for endoprothetic pair ceramics/metal- polyethylene and the polyethylene debris have irregular shape. In this article we would deal with the effect of lubrication on coefficient of friction. The average coefficient of friction in endoprosthesis is 0,3 that is more than 10 times higher as coefficient of friction in the healthy human joints (0,01 < f < 0,1 [2]). 2. Lubrication in hip joints

The fluid flow in endoprosthesis is described by Navier-Stokes equation that describes the equilibrium between mass, pressure and viscose forces.


8

).(. vpUgradgradvvtv

G Δ++−=+∂∂ ν

ρ (1)

The viscose forces are the basic benefit of fluid in the healthy hip joint gap and effects in decrease of coefficient of friction. The lubrication fluid in hip joint is called the synovial fluid and is captured in synovial membrane around the whole joint. The elementary component of synovial fluid that is responsible for the excellent lubrication properties is hyaluronic acid. The solution of hyaluronic acid is used also for viscosuplemantation- to add the absenting lubrication layer in joint as the first solution of degenerative diseases. The solution of hyaluronic acid would be used also in our experiment as testing lubrication fluid. Thy synovial fluid behaves according to the shear rate as Newtonian or Non-Newtonian fluid. The dynamic viscosity of synovial fluid is described:

20

1 BXAXp ++−

+= ∞∞

μμμμ (2)

hvX ∂∂= /1 (3) where μ∞ - dynamic viscosity of synovial fluid for high shear rates, over 105 s-1;

μ0 - dynamic viscosity of synovial fluid for low shear rates; X – shear rate ratio; v1 – circumferential component of synovial velocity; h – high of the gap; A,B – empiric coefficients, for healthy joints A= 1,88307, B= 0,00458 and for pathological joints A= 0,03349, B= 0,00131.

The character of lubrication in human joint is changing during the motion. According to the Dowson (2001) and Medley (2001) is lubrication determined by coefficient λ that is derived from following equation [3]:

´´

min

Rah

=λ (4)

where hmin minimum thickness of synovial fluid;

Ra’ composite roughness of endoprothetic pair. According to the (4), it is determined the character of lubrication: 0,1 < λ < 1 critical lubrication, 1 ≤ λ ≤ 3 mixed lubrication, λ > 3 thin flow lubrication or hydrodynamic. Critical lubrication means that the layer of fluid is so thin that there is a high risk of direct contact of materials of joint. The thin layer lubrication is secured with minimum thickness of lubrication layer 0,15 – 0,25 μm [3] and in this region we obtain the lowest value of coefficient of friction as it is visible in fig.2.


9

Fig.2 Stribeck´s curve of lubrication on joints[1]

of experiment

The stand for testing of endoprosthesis and their properties was designed in the

3. Description

laboratories of Institute of chemical and hydraulic machines and equipment of Faculty of Mechanical Engineering of STU in Bratislava. The stand is designed according to the standards ISO 142 42 for stand for testing of endoprosthesis of hip joint and secures the prescribed value of vertical load as well as the horizontak displacement value. The force and motional system is secured by hydraulic components from company FESTO Slovakia s.r.o. and demanded limits are set by the sensors: load cell, displacement sensor and magnetic sensor of position on the valve.

Fig.3 The stand for testing of effect of lubrication

As it was noted in the beginning the purpose of the measurements is the verification of the

on coefficient of friction. The measurement is done in

1. Phase A – simplified model of endoprosthesis of hip joint, with added lubrication layer friction, no lubrication layer

effect of lubrication in endoprosthesis of hip joint 2 steps-phases.

2. Phase B - simplified model of endoprosthesis of hip joint, dry


10

Fig.4 Position of strain gages on hip joint

To capture the data from measurement we have used the following sensors: - one-axis strain gage 1-LY11-1.5/120, sensitivity0,1 %, produced by HBM; - subminiature stainless steel compression load cell LC 302-± 0,5 % from range, produced by OMEGA; - inductive displacement tra

ensor of temperature ALM

ta was made with twBM th

1K, measuring range 457 kg, accuracy

produced by HBM; s

o softwares. Software CATMAN from company H

nsducer WA100, measuring range 0-100mm,EMO 5690-2. -

The evaluation of measured da

at help us to read the obtained data from QUANTUM MX 1615, and computational software MATLAB for next evaluation of measured data.

Fig.5 Software for evaluation of measured data

The measurement properties from phases A and B are following: Date of measurement: 17.6.-10.7. 2014 Place: STU SjF Bratislava, Length of one cycle: 1,2s The length of loading cycle: simulation of 2 days walk Lubricant: solution of hyaluronic acid 4. Results

The results from the experiment are on the figures 6-9. From figures follows that addition of lubrication layer causes decrease of coefficient of friction from maximum value captured in phase B - dry friction 0,2062, to the value for phase A with added lubricant 0,0502.


11

10 10.5 11 11.5 12 12.5 13

-15

-10

-5

0

5

10

15

Fáza A: endoprotéza bez úp

Čas [s]

Drá

ha v

ertik

ravy s mazaním hyaluronanom

álne

ho v

alca

- fle

xia

a ex

tenz

ia c

hôdz

e [m

m]

10 10.5 11 11.5 12 12.5 13

-0.075

-0.05

-0.025

0

0.025

0.05

0.075

Koef

icie

nt tr

enia

[-]

10 10.5 11 11.5 12 12.5-20

-15

-10

-5

0

5

10

15

Fáza A: endoprotéza bez úpravy s mazaním hyaluronanom

m]

Čas [s]

Drá

ha v

ertik

ia [m

3500

a e

xten

zia

chôd

zeál

neho

val

ca- f

lex

10 10.5 11 11.5 12 12.50

500

1000

1500

2000

2500

3000

Verti

káln

e zaťa

ž

Fig.6 Phase A, Horizontal loading and coeffiecient of fricton with respect to the time, Vertical and horizontal

loading with respect to time, endoprosthesis with added lubricant

enie

[N]

9.8 10 10.2 10.4 10.6

0.04

0.03

0.02

0.01

0

-0.01

-0.02

-0.03

-0.04

-0.0510.8

Fáza A: endoprotéza bez úpravy s mazaním hyaluronanom

Koe

ficient tr

enia [-

]

Fig.7 Phase A, ant

Čas [s]

Coefficient of friction, endoprosthesis with added lubric

333.5 334 334.5 335 335.5 336

-15

-10

-5

0

5

10

15

Fáza B: endoprotéza bez úpravy, bez prídavného mazania

Čas [s]

lca-

0.25

Drá

ha v

ertik

álne

ho v

a fl

exia

a e

xten

zia

chôd

ze [m

m]

333.5 334 334.5 335 335.5 336-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

Koe

ficie

nt tr

enia

[-]

333.5 334 334.5 335 335.5 336-20

-15

Fáza B: endoprotéza bez úpravy, bez prídavného mazania15

-10

-5

0

5

10

Čas [s]

Dr

a- fl

exia

a e

xe

[

3500

mm

]

3000

áha

verti

káln

eho

valc

tenz

ia c

hôdz

2500

333.5 334 334.5 335 335.5 3360

500

1000

1500

2000

[N]

nie

ežať

a ze

Ver

tikál

n

Fig.8 Phase B, S Horizontal loading and coeffiecient of fricton with respect to the time, Vertical and

horizontal loading with respect to time, endoprosthesis with dry friction

332 332.1 332.2 332.3 332.4 332.5 332.6 332.7 332.8 332.9

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

Fáza B: endoprotéza bez úpravy, prídavného mazania

Čas [s]

Koe

ficient

tren

ia [-

]

Fig.9 Phase B, Coefficient of friction, endoprosthesis with dry friction


12

5. Conclusions

The addition of lubricant into the endoprosthesis gap is significant step in decreasing of coefficient friction and we could derive that could also positively effect the lifetime of endoprosthesis. This results would continue to the lifetime tests of endoprosthesis with simulation of one year walking, representing 1 million of cycles.

Fig. 10 Resulting coefficient of friction

REFERENCES

[1] COLES, J. M. – CHANG, D. P. – ZAUSCHER, S. 2010. Molecular mechanisms of aquaeous boundary lubrication by mucinus glycoproteins . In Current Opinion in Colloid & Interface Science, 2010. Vol. 15, s. 406 – 416., ISSN 1359-0294 [2] KLEINSTREUKRER, C. 2006. Biofluid Dynamics. Boca Raton: CRC Press Taylor & Francis Group, 2006. 492 s. ISBN 0-8493-2221-9. [3] SEEBECK, P. 2009. Clinical and Technical Review: Hyaluronic acid (Hyaluronan). TECOmedical Group, 2011. [online]. [cit.2012-02-12]. 24 s. Dostupné na: http://www.tecomedical.com/downloads/pdf/Hyaluron%20%28e%29%20%28 10%29.pdf>. [4] MATTEI,L.-DI PUCCIO,F.-PICCIGALLO,B.-CIULLI,E., 2011, Lubrication and wear modelling of artificial hip joints: A review, In Tribology International, vol.44, 2011, s. 532-549, ISSN 0301-679X [5] NEČAS, L. a kol. 2009. Sloveský artroplastický register. Analýza 2003 – 2008. Martin: SAR, 2009. [citovane 2011-01-24]. Dostupné na: <http://sar.mfn.sk/file/subory/SAR_analyza_2003_2008.pdf>. [6] PRIKKEL, K.- HARINGOVA, A., 2012, Hip joint endoprosthesis. SK50222012 (U1)

[citovane 2014-08-25]. Dostupné na: <http://worldwide.espacenet.com/publicationDetails/biblioDB=worldwide.espacenet.com&II=4&ND=3&adjacent=true&locale=en_EP&FT=D&date=20120903&CC=SK&NR=50222012U1&KC=U1>.

[7] PRIKKEL, K.- HARINGOVA, A., 2012, Hip joint endoprosthesis. SK50232012 (U1) [citovane 2014-08-25]. Dostupné na: <http://worldwide.espacenet.com/publicationDetails/biblioFT=D&date=20120903&DB=worldwide.espacenet.com&locale=en_EP&CC=SK&NR=50232012U1&KC=U1&ND=4>.

[8] HARINGOVÁ, A. - PRIKKEL, K. - STRACÁR, K.: The lubrication in hip joint. In: Hidraulica - ISSN 1453-7303. - No. 1 (2014), online, p. 26-31 [9] HARINGOVÁ, A. - PRIKKEL, K.: The possibilities of modification of endoprosthesis of hip joint according to the usage of hydraulic components. In: Hidraulica. - ISSN 1453-7303. - No. 3-4 (2011), p. 28-33


THE USE OF BIOCHAR AS A MEANS OF SOIL REGENERATION Dipl.Eng. Sava ANGHEL1, Dipl.Eng. Alina Iolanda POPESCU2

1, 2 INOE 2000 – IHP, [email protected]

Abstract: Intensive agriculture exploitations led to pronounced degradation of soil by altering soil structure, affecting natural circuits of water, carbon and nitrogen by presence of poisonous substances from pesticides family, of residues of harmful substances resulted by conducting crop treatments. One way to remedy these soils, used worldwide, is the use of activated carbon as the biochar. It copies the natural phenomenon of vegetation fires after which due to the resulting carbon is gets to soil regeneration. Aim of the study is to increase production by regenerating the soil as a result of using biochar and food fortification for targeted interventions, at poor households around the world.

Keywords: biochar, greenhouse gases, biomass, pyrolysis, TLUD module

1. Introduction

In development perspective of sustainable agriculture is required efficient use of resources to increase their energy independence of technological processes, to reduce the use of mineral fertilizers in increasing the productive potential finality of agriculture. A relevant synthetic indicator is energy balance of crops that can show which the level of energy independence is and how it contributes to reducing the carbon concentration in the atmosphere.

Research in the use of biomass for energy production led to the conclusion that the plant coal, called biochar, resulting from pyrolysis and gasification processes is a valuable amendment for agriculture soils and an effective and very economical carbon sequestration.

Biochar is a product rich in carbon, created by thermochemical gasification of biomass with air in slow substoichiometric regime. Biochar is produced organically, it increases crop yield, improves the effectiveness of fertilizers, eliminates significantly the pesticides, reduces emissions of methane and nitrous oxide (two aggressive greenhouse gases) and stores carbon atmospheric in soil over a large period. It is widely highlighted as a method for reducing concentrations to carbon dioxide (CO2) in the atmosphere, mitigating climate change dynamics. The exchange of carbon between plants, soil and the atmosphere exceeds the exchange between ocean and the atmosphere.

2. Methodology

Inorganic fertilizers used for growing crops produce on short-term intensive energy and carbon. The use of these fertilizers in soils emits nitrous oxide, a powerful greenhouse gas emission. Globally, fertilizer production is the largest source (38 %) of emissions from agriculture (EPA, 2010). Reduced doses of inorganic fertilizer by incorporating biochar into soil would therefore reduce CO2 emissions related to agricultural production.

Biochar is a very important element that participated in time, by accidental burning of vegetation, at formation of productive layer of the present soil. A new biochar can be enriched with nitrogen and used as a valuable agricultural amendment, as a substitute for chemical fertilizers with nitrogen.

Internationally, there are known concerns in the use of production technologies of carbon by controlled burning of plant materials.

Pyrolysis involves trade-offs between the production of biochar, bio-oil and gas, and the process can be calibrated to maximize the output of different products, depending on economic factors. This is illustrated in Table 1.

13


Table 1: Typical product yields (dry wood basis) obtained by different modes of wood pyrolysis.

Source: International Energy Agency 2007

There are known methodologies for obtaining coal by burning wood in covered pits, or in stacks on the soil surface as shown below (Figure 1).

Fig.1 Methodologies for obtaining coal by burning wood in covered pits, or in stacks on the soil surface

Another example is the establishment of an open-plan kitchen stove TLUD. The focus is on the bottom of the stove where biomass burning occurs under the action of primary air that is adjustable. The results from pyrolysis are biochar, heat energy and biogas. By the middle part enters the secondary air, which burns the biogas at the top where one can cook.

Mode Conditions Bio-oil Biochar Gas

Fast Moderate temperatures (500°C) for 1 second 75% 12% 13%

Intermediate Moderate temperatures (500°C) for 10–20 seconds

50% 20% 30%

Slow (carbonisation)

Low temperature, (400°C), very long solids residence time

30% 35% 35%

Gasification High temperature, 800°C, long vapour residency time

5% 10% 85%

14


Fig. 2. Schematic of a top-lit updraft (TLUD) gasifier wood cook stove. (according to Brown RC (2009) Biochar Production Technologies in Lehmann, J., & Joseph, S. (Eds.) Biochar for

Environmental Management: Science and Technology. London: Earthscan.)

Research has been conducted on effective use of biochar in soil obtained in controled field in shifting cultivation and in field in shifting cultivation with biochar embedded in soil.

Fig.3 The effect of using biochar after five years of application (- is more stable that any soil amendment (MRT 1,000-2,000 yrs);

- increases nutrient availability beyond a fertilizer effect; -is more efficient at enhancing soil quality than any other organic soil amendment)

Data on biochar technology (fig.4) and functional diagram (fig.5) of a module type TLUD is shown below.

15


Fig.4 Biochar technology of a module type TLUD

Energy module type TLUD consists of a reactor which is filled with biomass and is introduced in a case that has two adjustable air circuits. Gasification air enters through the bottom and ensures the production of heat, oxidation and gasification of biomass, obtaining biochar and gas produced by gas generator (gengas). The second circuit provides preheating of combustion air which is mixed with the gas produced in the upper side and ensures burning of the gengas causing heat.

Fig.5 Functional diagram of a module type TLUD

Functional block diagram of an energetic module type TLUD - Input values are: biomass, air, task order, and output: biochar, heat, products of CO2 combustion.

If a source of carbon is added to the soil without sufficient nitrogen, microorganisms must scavenge nitrogen from the soil environment, which can result in little nitrogen being available for plants which can greatly limit crop growth. In general, an amendment needs to have a C:N ratio that is no higher than about 30 to avoid nitrogen immobilization (the additional C is used for maintenance respiration).

Biochars, which are mostly carbon, usually have very high C:N ratios on an elemental composition basis; fortunately, nearly all of this carbon will not be available to microorganisms meaning that the effective C:N ratio is much lower. If a biochar is not pyrolyzed sufficiently,

16


however, some of the carbon may still be bioavailable and may cause nitrogen immobilization, resulting in short-term negative effects on crop yield. Depending on magnitude of the carbon overloading, the nitrogen in the microbial biomass will eventually become plant-available again as microorganisms die off and the nitrogen is recycled, but by then (a few weeks to a few months later), the plants may not be able to recover. An example of nitrogen immobilization is shown in Figure 6. In this study, corn stover and carbonized corn stover (i.e. corn stover biochar) were used as soil amendments in pots growing corn.

The third case is nitrogen immobilization due to a high ratio of available carbon to available nitrogen in the biochar amendment. When they are actively growing (i.e. producing more biomass), microorganisms need about 1 mole of nitrogen for every 5 to 10 moles of carbon that they consume.

Both amendments had high C:N ratios but only the corn in the pots with the highest rates of uncarbonized amendment showed signs of nitrogen immobilization (the stunted plant growth in pots with 1.0 and 2.0% by weight of corn stover added).

Fig. 6. An example of nitrogen immobilization by microorganisms: the effect of soil amendment bio-available C: N ratio on corn growth in a greenhouse study

Soils used in the study were amended with either corn stover (CS), which had a high

available C:N ratio, or carbonized corn stover (CCS), which had a much lower available C:N ratio due to the carbonization process, at applications rates of 0.5, 1.0 or 2.0 wt% of soil. The corn grown on soils amended with the higher amounts of corn stover (total C:N = 71) did worse than that grown on soils amended with the carbonized crop residue (total C:N = 49). (Source: Christoph Steiner, Biorefining and Carbon Cycling Center, University of Georgia, USA.)

Scientific innovation of the work results from biochar application in Romanian agriculture, process known worldwide but at us only at the beginning

In Romania we know works in the field conducted at: > Metallurgical Research Institute ICEM SA, in partnership with the Municipality of Motru,

SNLO Miami and IPROCHIM SA have under implementation, since July 2002, the project of obtaining activated carbon by exploitation of xylose using clean technologies.

> the ICDP Maracineni, the project PC 51-008/14.09.2007- concerns regarding the use of black coal in fruit growing.

Our institute has collaborated with partners such as Politehnica University of Bucharest, INMA Bucharest in research works for obtaining active carbon as a byproduct of gas-producing

17


and TLUD modules, developing in works under the national programmes RELANSIN and PARTNERSHIPS.

> RELANSIN: motor pumps for irrigation, fueled by gas produced by gasification of plant debris.

> RELANSIN: storage and distribution facility for gas produced by a generator. > PARTNERSHIPS: Research on the use of corn crop as a source of biomass for thermal

energy production. Food security, the challenge of ensuring the availability of safe, nutritional and accesible

food, took a new dimension in the light of increased global demand, environmental restrictions on agricultural production and increased competition for soil quality and the means for obtaining it.

3. Conclusions

Modern experimental research demonstrates that biochar application can substantially raise productivity of crops such as soybeans, sorghum, potatoes, maize, wheat, peas, oats, rice and cowpeas.

Evidence suggests that significant productivity gains are possible at application rates as low as 0.4 to 8 tonnes of carbon per ha, but at extremely high applications crop productivity may actually drop due to nitrogen limitation.

Much synthetic fertilizer is currently produced by using natural gas to synthesis ammonia using nitrogen from the air, but this releases one molecule of carbon dioxide for each molecule of ammonia produced. Conventional urea-based fertilizers, made from this ammonia, also have other adverse environmental impacts when used inappropriately. Combining ammonia, carbon dioxide and water in the presence of biochar forms a solid, ammonium bicarbonate fertilizer, inside the pores of the char. This nitrogen-enriched char can be incorporated into the soil, where it serves three purposes: as a carbon store, as nitrogen fertilizer, and as a biologically active soil enhancer.

REFERENCES

[1] S. Anghel, C. Dumitrescu, Gh. Sovaiala, “Research study regarding the making of maize stalks briquettes”, Wroclaw, 7-9 Oct. 2009, Conference Proceedings, pp. 349-353

[2] E. Murad, A. Culamet, G. Zamfiroiu, “Biochar- Economically and ecologically efficient technology for carbon fixing”, International Symposium HERVEX-2011, Călimăneşti, 9-11 November 2011, Conference Proceedings, ISSN 1454-8003, pp. 37-43

[3] E. Murad, A. Ciubucă, A. Culamet, Radu Marian, “Biochar produced from vine prunings organic soil amendment for viticulture”, Symposium ICDVV, Valea Călugărescă, 12 June, 2012

[4] E. Murad, F. Dragomir, “Heat generators with TLUD gasifier for generating energy from biomass with a negative balance of CO2”, International Conference HERVEX 2012, Călimăneşti, 7-9 November 2012, Conference Proceedings, ISSN 1454-8003, pp. 440-447

[5] D. Sumedrea, C. Marin, E. Chiţu, C. Nicola, M. Sumedrea, V. Chiţu, M. Călinescu, M. Butac, “Preliminary results regarding the influence of black charcoal application in apple orchards on chemical and microbiological properties of the soil”, International Symposium, 2010, Annales of the University of Craiova, vol. XV (XLXI), Publishing House Universitaria, Craiova, ISSN 1453-1275, pp. 534-543, http://anucraiova.3x.ro, CNCSIS B+.

[6] P. Winsley, “Biochar and Bioenergy production for climate change mitigation”, International Energy Agency, 2007, New Zealand Science Review, Vol.64. 1, 2007, pp. 5-10

18


ELECTRONIC SCREENING

Ing. Justinian Laviniu CÎRSTEA, doc. Ing. Dorel STOICA 1 1 , University POLITEHNICA of Bucharest, Faculty of Biotechnical Engineering [email protected] , [email protected]

Abstract: The article deals with the electronic screening of the commercial vehicles, which can be done using mainline screening and ramp screening. Mainline screening allows vehicles to be cleared without pulling into the station and has the advantages of a reduced traffic volume entering the station facility and of a minimized delay for safe and legal vehicles, but also has the disadvantage that the in-road equipment repairs on the mainline can be very costly and disruptive. Ramp screening is performed at lower speeds within the confines of the station and approach ramp. The purpose of the e-screening is to ensure a safe and optimal traffic. Keywords: e-screening, CVISN, PrePass, NorPass.

1. INTRODUCTION Commercial Vehicle Information Systems and Networks (CVISN) is the collection of state,

federal, and private sector information systems and communications networks that support commercial vehicle operations. Electronic screening is one of the three key program areas in CVISN Level 1.

WHAT IS ELECTRONIC SCREENING?

Screening is a selection mechanism to target high-risk operators and make efficient use of weigh station and inspection resources. Electronic screening (e-screening) is the application of technology to make more informed screening decisions. Properly implemented, electronic screening results in improved traffic flow, focuses vehicle inspections and ultimately achieves the goals of increased safety and reduced operating costs. In electronic screening: • DSRC is used to identify the vehicle, store and transfer other screening data, and signal the driver of the pull-in decision. • Electronic Data Interchange (EDI) may be used to transmit safety and credentials history (snapshot) data from the information infrastructure to the roadside systems to assist in the screening decision.

The application of electronic screening will be affected by many constraints, including site limitations, availability of support staff, and funding. Each roadside check station is likely to have a unique design. Each station’s design is unique because of: • State policy and practices • Traffic flow, volume, and number of lanes • Available site space • Legacy system characteristics • Existing proprietary solutions • Vintage of roadside facilities and communications equipment • Resources available for making changes.

19

mailto:[email protected]



2. Technologies

There are a variety of technologies that can be applied to electronic screening in support of the commercial vehicle weigh and inspection process. There are also a number of ways in which these technologies can be applied. The purpose of this section is to briefly describe some of the basic technologies used in electronic screening.

2.1 Dedicated Short Range Communications (DSRC)

DSRC is used to provide data communications between a moving vehicle and the roadside equipment to support the screening process. This is accomplished by means of a transponder (also known as a “tag”) mounted in the cab of the vehicle, and a reader and antenna mounted at the roadside. The tag may contain identifiers specific to the vehicle (carrier and vehicle IDs), plus optional prior screening event information. The transponder has audio and visual indicators that may be used to signal the driver. The term Automated Vehicle Identification (AVI) is often used when referring to DSRC systems. Strictly speaking, AVI is any technology, including DSRC, used to identify vehicles. This category also includes optical, audio, and other Radio Frequency (RF) identification systems.

2.2 Weigh In Motion (WIM)

WIM is used to measure approximate axle weights as a vehicle moves across the sensors, and to determine the gross vehicle weight and classification based on the axle weights and spacings. Although not as accurate as a static scale, WIM allows the weight of a vehicle to be estimated for screening purposes while maintaining traffic flow.

2.3 Automatic Vehicle Classification (AVC)

Axle detectors are used to classify the various vehicle types. This information is necessary at WIM-equipped sites because vehicle classification plays a role in the determination of legal weight. AVC units are also used in compliance subsystems to detect vehicles bypassing the station.

2.4 Vehicle Tracking Loops

Inductance loops may be used to track vehicle positions as they proceed through the site.

This information is required to synchronize lane signaling with the correct vehicles and to verify compliance with these signals.

2.5 Automatic Signing

Lane signals and variable message signs should be automatically controlled by roadside

operations and coordinated with the detected location of the vehicle. Precise timing and control of these signals is required in order to ensure that unambiguous direction is given to the intended vehicle. Misdirection, confusion and ambiguity may result if signals intended for one vehicle are visible to and misread by another.

3. Data Exchange

A critical component of the CVISN architecture is the standardization of two interfaces:

computer-to-computer exchanges using EDI and vehicle-to-roadside exchanges via DSRC. The EDI interfaces are primarily used to transfer information between public agencies (e.g., state government to state government) or between a public agency and private sector entity (e.g., state

20


government to motor carrier). The computer-to-computer interfaces may evolve from the use of EDI to the use of XML and other Web-based protocols.

Another component to standardization of data exchange between state and/or public systems is the use of common data “snapshots.” Snapshots contain information that provide a quick picture of carrier/vehicle/driver safety performance history and basic credentials information. Carrier and vehicle snapshots exchange safety and credentials data between state and national systems. The snapshots are used in conjunction with DSRC messages to support roadside operations as shown in Figure 1. Figure 1 shows the data flow among the various systems supporting electronic screening.

WHAT ALREADY EXISTS?

A large body of knowledge and experience already exists for deploying electronic screening systems and technologies. Member states of two major multi-state electronic screening programs, Heavy Vehicle Electronic License Plate (HELP) PrePass™ and North American Preclearance and Safety System (NorPass), have deployed a number of sites that are currently in operation. The CVISN pilot and prototype states have completed or are in the process of developing electronic systems that meet CVISN Level 1 requirements. Software products and design documents, developed for CVISN with FMCSA funds, are available in the public domain. These products include the Roadside Operations Computer (ROC), Perryville Screening Computer, and the Commercial Vehicle Information Exchange Window (CVIEW) systems.

4. Programs

Heavy Vehicle Electronic License Plate (HELP) PrePass™ is the largest North American electronic screening program with operational sites in Alabama, Arizona, Arkansas, California, Colorado, Florida, Illinois, Indiana, Iowa, Louisiana, Mississippi, Montana, Nebraska, Nevada, New Mexico, Ohio, Oklahoma, Tennessee, West Virginia, and Wyoming. The PrePass™ Service Center manages pre- and post-enrollment verification checks of carriers and provides transponders for

21


vehicles. At the roadside station, transponder-equipped vehicles are checked against a pre-clearance list and weighed using WIM equipment.

North American Preclearance and Safety System (NorPass) was created in the merger

of Advantage CVO and Multi-jurisdictional Automated Preclearance System (MAPS). States that have signed the NorPass agreement include: Kentucky, Georgia, Idaho, Utah, and Washington. Information based on safety and credential records is passed to the roadside stations via an enrolled vehicle list. Weight enforcement may be conducted using WIM or weight compliance history. Kentucky (KY) and Washington (WA), two CVISN pilot states that are also NorPass members, are nearing completion of electronic screening sites that should meet the roadside CVISN Level 1 requirements.

Greenlight – Oregon has implemented an e-screening program called Greenlight and has 21 Greenlight sites. Oregon provides its own transponder administration. Carriers are free to use the Oregon transponder in any or all other systems they choose. Oregon currently uses the carrier safety fitness rating and SafeStat score for its safety bypass criteria. Oregon Greenlight sites can only read the transponder ID code. If you are enrolled in Greenlight, the transponder ID will be associated with a license plate.

Maryland (CVISN prototype state) has implemented electronic screening, based on the CVISN architecture, at the Perryville, MD, inspection station. By successfully conducting several of the CVISN interoperability tests, Maryland became the first state to meet the roadside CVISN Level 1 requirements.

5. Operational concepts and scenarios

The term “operational concept” generally means “how a system is used in various operational scenarios.” “System” is used here in a broad sense to include people and manual processes as well as automated information, sensors, and control systems. New operational concepts are adopted in order to solve a problem in the current operations or to take advantage of new knowledge or technology that enables improvements in current operations.

CVISN electronic screening operational concepts include necessary steps toward achieving the goal of national interoperability among electronic screening systems. Realizing this goal will promote seamless and safer movements, equitable treatment, increased productivity, and uniform enforcement for the motor carrier community.

5.1. Operational Scenario The e-screening system deployed at Perryville, Maryland, is described in this section along

with the associated operational scenario. This site is unique because it includes both mainline and ramp screening systems. Due to cost, most electronic screening systems are either mainline-only or ramp-only. Maryland has elected this dual-capability configuration in order to compare the relative performance of the two methods. The listed scenario describes the combined operation of the two subsystems and function of the various components. The operational scenario for a ramp-only or mainline system can easily be derived from the information presented.

5.1.1 Site Layout

Figure 2 illustrates the site layout for the e-screening system being deployed at Perryville, MD. All major roadside equipment components are shown in the figure. The key features of this layout are:

22


• Mainline Piezo WIM/AVC in the right-hand southbound lane on I-95, approximately one mile upstream of the station • Over-height (OH) detector collocated with mainline WIM • DSRC reader (Advance) collocated with mainline WIM • DSRC reader (Notification) located approximately ¼ mile upstream of the ramp approach. The location of the notification reader must allow sufficient time for the vehicle operator to receive the bypass/pull-in signal via DSRC and safely remain on I-95 or pull onto the station ramp • AVCs across all three south-bound lanes of I-95, downstream of the station ramp • DSRC reader (Compliance) collocated with AVCs. The compliance readers shall cover only the right-hand lanes on I-95. Trucks will be restricted to these lanes when bypassing the station • Load-cell WIM in ramp lane • DSRC reader (Ramp) on ramp, upstream of WIM • Over-height detector installed near ramp reader • Overhead signs directing traffic back to I-95 or onto the static scale • DSRC reader (Static Scale) collocated with the station static scale • Tracking loops installed as necessary.

5.1.2 E-Screening Operational Scenario In the site layout shown in Figure 2, there are five DSRC readers along with both ramp and

mainline WIM. The five DSRC readers shown in this configuration are: advance reader, notification reader, compliance reader, ramp reader and static-scale reader. The advance reader’s function is to read the screening message, including the carrier and vehicle identifiers, and to send this information to the screening computer for use in determining whether to clear the vehicle without pulling into the station. The reader is located far enough ahead of the notification reader that the mainline screening subsystem has time to complete all necessary processing as the vehicle approaches. The advantages of screening on the mainline are to control traffic volume entering the

23


station facility and to minimize the delay for safe and legal vehicles. The mainline WIM/AVC provide vehicle weight estimates as input to the mainline screening decision. Gross vehicle weight along with axle weights and spacing are available. Although not as accurate as either a static scale or ramp WIM, the weight estimates are sufficient to clear a significant portion of the vehicle traffic.

At the notification reader, a signal is transmitted to the vehicle to convey the screening

decision status to the driver. Since a DSRC-equipped vehicle could be signaled to pull in, the notification reader must be deployed far enough from the roadside check facility for the vehicle’s driver to be able to react without endangering other vehicles on the roadway. Reaction time budgets should account for slowing and turning off the mainline, as well as crossing lanes of traffic.

By the time the vehicle has passed the advance and notification readers, it has been electronically cleared. However, it is also necessary to verify that vehicles are not illegally bypassing a check station. Therefore, a compliance reader and an AVC system are located on the mainline, past the entrance ramp to the station. The AVC identifies un-tagged commercial vehicles that have illegally passed the station. The reader checks tagged vehicles to verify that the vehicle was cleared to bypass the station. If a violation is detected, an indication is given to enforcement personnel. Vehicles entering the check facility ramp would fall into one of the following categories: • DSRC-equipped, valid legal weight – the vehicle has been identified via DSRC, a valid weight has been recorded, and an active screening decision has been made to stop the vehicle for some type of closer review. This may be based on specifically identified problems or may be due to random selection. Closer review may be limited to a visual check while on the static scale, or may include an inspection based on the visual review, on data reported back in the screening process, or on random selection. • DSRC-equipped, invalid or over-weight – the vehicle has been identified via DSRC; however, either the WIM failed to properly register the weight or the detected weight exceeded the criteria. • DSRC-equipped, unrecognized – the vehicle is equipped with a transponder; however, the tag may either be incompatible with or not valid for use at the site. • No DSRC.

Upon entering the facility ramp, vehicles will be processed by the ramp WIM. The DSRC ramp reader will interrogate the vehicle tag to retrieve the relevant identification data. A screening decision will be made and the vehicle will be subsequently directed by visual lane signals. Cleared vehicles will be signaled to return to the mainline. Vehicles receiving a pull-in decision on the ramp will be directed to the static scale. The static-scale reader is used to identify transponder-equipped vehicles that are on the scale. Snapshot-based safety and credential data for the vehicle will be available to the static scale operator.

REFERENCES 1. Intelligent Transportation Society of America, Fair Information Principles for ITS/CVO.

2. JHU/APL, CVISN Electronic Screening Functional Specification for Southbound I-95 at

Perryville, MD, POR-01-7298 V1.0, January 2001.

3. JHU/APL, Delivery of Recommended Practices and System Specification Documents for Enhanced Electronic Screening.

24


TILLER HYDROSTATIC TRANSMISSION

Phd.eng. Gheorghe Ivan*, Phd.eng. Radu Ciuperca*, Phd.eng. Ganea Ioan* *INMA Bucharest, [email protected] Abstract: The article relates to a hydrostatic transmission intended for the tillers equipped with

internal combustion engines for continuous transmission of motion and power of the drive wheels or to a device for digging soil. The state of the art transmission tillers operated internal combustion engines using classical scheme consists of clutch, gearbox, control systems thereof etc. Chaining these elements presents disadvantages, on the one hand because they are complicated, bulky and heavy, requires a large number of control systems for drive and on the other hand that the transmission of the movement is done in steps. The hydrostatic transmission we propose simplify construction of tillers and control systems for its operation and will mount easily on the transmission instead of classical combustion engine. This transmission is made up of a variable displacement hydraulic pump which is connected to the internal combustion engine, an orbital hydraulic motor to drive the wheels of the driving or digging the ground equipment, on which is mounted a framework for the internal combustion engine, hydraulic pump and motor hydraulic pipes connecting the hydraulic motor and hydraulic pump.

Keywords: tiller, hydrostatic transmission. Introduction A tiller is a self-propelled vehicle, usually having two drive wheels, internal combustion engine

through a gearbox and clutch, operated by a handlebar of a leader who walk. The engines full power more than 15 kW and are powered by gasoline or diesel. The moving of tiller has different speeds, forward or backward, gears and moving purposes are changed using control systems located on the handlebars.

The tillers are used in horticulture and gardening soil processing using specific equipment attachments (plough, milling unit, ridge plough, cultivator, digging canals for irrigation equipment, digging pits equipment, equipment for crown shaped shrubs and trees, irrigation pump etc.). Also, the some tillers can pull a trailer on two wheels, the driver sitting in a chair.

The tiller to replace the mechanical transmission with a hydrostatic transmission is type produced by S.C. RURIS

Technical and functional characteristics of the tiller with mechanical transmission and hydrostatic transmission are presented in Table 1.

Technical and functional characteristics of the tiller Table 1

Technical and functional characteristics

Values mechanical transmission

Values hydrostatic transmission

full power engine (net power) 5.5 kW (4.8 kW) maximum RPM engine 3600 rpm RPM drive wheels 40...125 rpm maximum resistant torque, mrmax 30 daNm clutch dry single disc clutch - gearbox 2 forward, 1back - reducer - geometric volume hydraulic pump - 7,08 cm3/rot

25



theoretical flow of hydraulic pump - 25,5 l/min to 3600 rpm operating pressure - 210 bar geometric volume hydraulic motor - 125,7 cm3 / rot oil flow of the hydraulic motor - 5,6 ÷ 17,4 l / min metal wheels diameter 400 mm weight 65 kg 42 kg

The mechanical transmission, consists of clutch, gearbox and reducer, is replaced with hydrostatic transmission, consists of variable displacement hydraulic pump which is connected to the internal combustion engine, an orbital hydraulic motor to drive the wheels of the driving or digging the ground equipment, on which is mounted a framework for the internal combustion engine, hydraulic pump and motor hydraulic pipes connecting the hydraulic motor and hydraulic pump. In Figure 1 is presented the tiller with mechanical transmission.

Fig.1 Tiller with mechanical transmission

1. TILLER WITH HYDROSTATIC TRANSMISSION The tiller with hydrostatic transmission is mainly composed of an internal combustion engine, a

flexible coupling, a variable hydraulic pump, two frames assembly, a hydraulic orbital motor with two axes, hoses and fittings and pump control system [Fig. 2].

26


Fig.2 Tiller with hydrostatic transmission

Calculation of hydrostatic transmission Internal combustion engine torque diagram is presented in Figure 3.

Fig.3 Internal combustion engine torque diagram

27


The tiller hydrostatic system will have variable flow hydraulic pump PMV0-07, driven by the

combustion engine at speed of np = 3000 rpm and an orbital hydraulic motor with two-axis output MRB 125, to drive the wheels of the driving or digging the ground equipment.

Hydrostatic installation diagram is presented in Figure 4.

Fig.4 Hydrostatic installation diagram

The total efficiency of the hydraulic motor is calculated with relation 1 [1]:

tm vm mmη = η η (1)

where ηtm is total efficiency of the hydraulic motor; ηvm – volumetric efficiency of the hydraulic motor, ηvm=0,9 ÷ 0,95; it is choose ηvm= 0,9; ηmm – mechanical efficiency of the hydraulic motor; ηmm= 0,9.

Resulting: ηtm = 0,81…0,85. For the calculation it is chosen: ηtm = 0,81.

Geometrical calculation of the hydraulic motor is calculated with relation 2 [1]:

( )2r max

gmn r mm

2π MV = 10p - p η (2)

where Vgm is geometric volume of the hydraulic motor, in cm3/rot; Mr max - maximum resisting moment, Mr max = 30 daNm; pn – nominal pressure of the hydraulic motor, pn = 210 bar; pr – the pressure in the return line; pr=4÷5bar; ηmm - mechanical efficiency of the hydraulic motor, ηmm=0,9.

Resulting: Vgm =102,16 cm3/rot.

It is choose hydraulic motor MRB 125 from Motors Catalog [2], with the following characteristics: - geometric volume: 125,7 cm3/rot; - maximum speed: nmax= 475 rpm; - maximum torque: Mmax = 30 daNm; - torque on the shaft A: MA = 20 daNm; - torque on the shaft B: MB = 20 daNm; - pressure drop: Δp = 175 bar; - maximum flow: Qm max = 60 l/min.

The oil flow of the hydraulic motor is calculated with relation 3 [1]:

gm mh 3m

vm

V nQ = 10

η−

(3)

where Qm is oil flow of hydraulic motor, in l/min; 28


nmh - RPM motor hydraulic, nmh = 40÷125 rpm;

ηvm – volumetric efficiency of the hydraulic motor, ηvm= 0,9.

Resulting: Qm = 5,6 ÷ 17,4 l/min. Total efficiency of hydraulic pump is calculated with the relation 4 [1]:

tp vp mpη = η η (4)

where ηtp is total efficiency of the hydraulic pump; ηvp – volumetric efficiency of hydraulic pump, ηvm=0,9÷0,95; it is choose ηvp= 0,9; ηmp – mecanichal efficiency of hydraulic pump; ηmp=0,9.

Resulting: ηtp = 0,81…0,85. For the calculation is chosen ηtp = 0,81. Geometric volume calculation of the hydraulic pump is calculated with the relation 5 [1].

pgp

p vp

1000QV =

n η

(5) where Vgp is the geometric volume of the hydraulic pump, in cm3/rot;

Qp - assured flow of hydraulic pump Qp = Qm = 17,4 l/min. np – RPM driving pump, np = 3000 rpm; ηvp – volumetric efficiency of hydraulic pump, ηvp= 0,9.

Resulting: Vgp = 6,44 cm3/rot Is chosen hydraulic pump PMV0 - 07 C1 M 00 A0 00 R from Poclain Hydraulic Catalog [3], with the following characteristics:

- geometric volume of the hydraulic pump: Vgp = 7,08 cm3/rot; - RPM driving: np = 700÷3600 rpm; - theoretical flow: 25,5 l/min, to 3600 rpm; - operating pressure: 210 bar; - maximum pressure: 300 bar; - inlet pressure: 0,8 bar; - mounting flange: SAE A; - setting: mechanical; - weight:7,5 kg (for setting mechanical).

The calculation of necessary power the hydraulic pump is made with relation 6 [1]

p maxp

tp

Q pP =

600 η (6)

Resulting: PP = 4,37 kW

The calculation of the torque consumed by the pump is made with relation 7:

pp

p

PM = 973,8

n (7)

where Mp is the consumed torque by the pump, in daNm. Resulting: Mp=1,42 daNm.

29


3. CONCLUSIONS Lately it tends to develop technical solutions to achieve tiller that allow much more control

over it safely and effectively, given that it is run and handled directly by the operator. More specifically, it is the ability to control the speed, so the movement no load, but especially in the work, knowing that a tiller can work with a very wide range of equipment.

From this point of view it required a much wider range of gear adapted to the work carried out and the nature and state of the ground work, which is not possible with current versions of tillers, they generally having only two working speeds, seldom three. To meet these requests, otherwise justifiable, it was realized a tiller with hydrostatic transmission.

The hydrostatic transmission, with variable displacement hydraulic pump and an orbital hydraulic motor, replace the mechanical transmission (clutch, gearbox and reducer), thus enabling a very wide speed range.

An other advantages of the hydrostatic transmission we propose, simplify construction of the tiller and for the control systems for its operation and will mount easily on the transmission instead of classical combustion engine.

The disadvantage of the hydrostatic transmission is lower efficiency and higher costs.

REFERENCES [1] P. Babiciu, V. Scripnic, Al. Fratila, "Hydraulic systems of tractors and agricultural machinery"

Ceres Publishing House, Bucharest, 1984 - pg.45, 239, 241; [2] M+S Hydraulic-Spool Valve Hydraulic Motors Catalog / Lyra firm; [3] Poclain Hydraulic Catalog - Variable Displacement Pump Closed Loop Circuit / Lyra firm;

30


31

RAINFALL INDICES IN THE CITY OF BUCHAREST

Carmen Otilia RUSĂNESCU

1 University Polytechnic Bucharest, Biotechnical Faculty of Engineering, [email protected] Abstract: In this paper is analyzed rainfall regime with rainfall indices: the amount of rainfall, conventional balance of humidity (K), emberger rainfall coefficient. Specific precipitation amounts are calculated analysis of the ecological factors that characterize either the period of accumulation of biologically active water horizon (XI-III) or maximum biological activity (VII-VIII). We performed conventional moisture balance. We calculated the average yearly rainfall in 2009-2012. We calculated the eco-climatic indices for the city of Bucharest, a city with a lot of vegetation, parks, and green spaces to highlight issues tend aridity of the region. According to the data processed, the city of Bucharest has a temperate continental climate. Specific four seasons, winter, spring, summer and autumn. Bucharest winters are very mild with little snow and relatively high temperature, while in recent years are very hot summers, very hot with little precipitation. Keywords: indices of rainfall, rainfall, annual precipitation 1. Introduction Bucharest is situated on the banks of Dambovita river that empties in Arges affluent of the Danube. Several lakes stretch along the river Colentina, within the city, as Floreasca lake Tei and lake Colentina, and in the center there is a lake in Cismigiu. This lake, former marsh the old medieval city, is surrounded by gardens Cismigiu, inaugurated in 1847. Besides Cismigiu, there is a number of large parks: Herastrau (the Village Museum) and the Botanical Gardens (the largest in Romania and includes over 10,000 species of plants, including exotic) Youth Park, Park Alexandru Ioan Cuza and more smaller parks and green spaces of the district municipalities [1] .

The climate and topography of the surroundings of Bucharest are very suitable for agriculture. Growing grain, vegetables and fruit trees. In addition a number of plants growing wild, damaging crops and which man tries to destroy them (weeds). The forests grow a wide variety of fungi, ferns and moss. [2]. The meteorological concept of aridity has a temporal reference, is a phenomenon characterized by low rainfall (period arid, arid year). Currently over a third of Earth's land is affected by aridity. The main drivers of aridity are: rainfall, temperature, continental, albedo, etc. [3]. Biogeographic point of view, the lack of water in the soil produces a growth deficit of plant species and even create large discontinuities in the carpet vegetable. And other authors have studied their works rainfall in different regions of the world [4,5]. 2. Materials and methods The amount of rainfall is monitored weather station. Technical specifications of precipitation sensor it is a digital sensor. Measuring range: unlimited; maximum measuring range: 0 to 300 mm / h. 3. Results and discussion Based on data recorded by the weather station 24 hours out of 24, we performed statistical analysis, and calculated the amounts of precipitation analysis specific ecological factors characterize either the period of accumulation of biologically active water horizon (XI-III) or maximum biological activity (VII-VIII).

The period from November to March is a time of excess water in the soil, the accumulation of which is very necessary but vegetation structure in the first two stages of vegetative (germination and sprouting).


32

High temperatures during this period leading to high values of actual evapotranspiration (Satmari, 2010). Due to the development of all the leaves, the plants are also needs maximum, which results in the depletion of water from the soil [6].

For weather station in Bucharest, we performed calculations based on data recorded by station and got the values shown in Figure 2.

Table 1 The amount of rainfall

The amount of rainfall recorded in the month XIX-III 2009 319The amount of rainfall recorded in the month XIX-III 2011 221.6The amount of rainfall recorded in the month XIX-III 2012 185.6The amount of rainfall recorded in the month VII-VIII2009 211.2The amount of rainfall recorded in the month VII-VIII2010 95.4The amount of rainfall recorded in the month VII-VIII2011 128.4The amount of rainfall recorded in the month VII-VIII2012 130.3

The sum of precipitation during the cold season of the year represents the total water amount resulted from both solid and liquid precipitation. The cold season is as important as the warm one from the pluviometric point of view, as it ensures the water reserve in the soil that is then used during the first phonological phases. The amounts registered during this interval represents about 35-40 percent of the annual mean, which is about 221.6 mm (2011). . The highest value is 319 mm in 2009 (Table 1).

The sum of the precipitation amounts during the maximum consumption period represents the precipitation amount corresponding to the interval July-August, when there are also registered the highest thermal values. These amounts represent about 19 percent of the annual mean. Generally, this interval is characterized by long and intensive drought periods. The highest values are 211.2 mm in 2009 and the lowest values in 2010 of 95.4 mm. The sum of precipitation during the cold season of the year represents the total water amount resulted from both solid and liquid precipitation. The cold season is as important as the warm one from the pluviometric point of view, as it ensures the water reserve in the soil that is then used during the first phonological phases. The amounts registered during this interval represents about 35-40 percent of the annual mean, which is about 221.6 mm (2011). The sum of the precipitation amounts during the maximum consumption period represents the precipitation amount corresponding to the interval July-August, when there are also registered the highest thermal values. These amounts represent about 19 percent of the annual mean. Generally, this interval is characterized by long and intensive drought periods. Cele mai mari valori sunt in anul 2009 de 211.2 mm iar cele mai mici valori in anul 2010 de 95.4 mm. We perform conventional balance of humidity (K) [7].

CTTP

K 010)10(

≥

≥=∑∑ (5)

58.320.4+24.6+25.4+22.94+19.4+13.4367.6+68.2+143+97.2+59.4+16.8=

2009 ==−

−=∑∑

IXIVTIXPIV

K

21.319.134+26.75+24.57+20.52+21.27+13.4833.2+26.2+69.2+102.4+119.6+52.6=

2010 ==−

−=∑∑

IXIVTIXPIV

K

09.321.92+24.46+24.95+22.5+17.7+12.02054.2+74.2+79.8+137.4+36=

2011 =+

=−

−=∑∑

IXIVTIXPIV

K

69.322.1+24.6+25+21.3+19.5+15.4

35.4+65.3+78.4+58.4+179.8+54.2=2010 ==

−

−=∑∑

IXIVTIXPIV

K

Conventional balance of humidity is favorable climate for the degree of forest vegetation.

Conventional balance of moisture values calculated for 2009-2012 based on the values of air temperature and rainfall recorded by the weather station, ranged between 3.09 and 3.69 so only part of the storm water gets up in the soil. We calculated the amount of rainfall recorded based on station in the years 2009 - 2012 and the maximum rainfall in the same period (figure 1 and 2).


33

Conventional balance of moisture is favorable climates for the degree of forest vegetation. Conventional balance of moisture values calculated for 2009-2012 based on the values of air temperature and rainfall recorded by the weather station, ranged between 3.09 and 3.69 so only part of the storm water gets up in the soil.

We calculated the amount of rainfall recorded based on station in the years 2009 - 2012 and the maximum rainfall in the same period.

Annual average amount of rainfall in 2009 is 708 [mm/year] Annual average amount of rainfall in 2010 is 652.2 [mm/year] Annual average amount of rainfall in 2011 is 510.6 [mm/year] Annual average amount of rainfall in 2012 is 721.9 [mm/year] The highest value of rainfall was recorded in 2009 by 708 [mm/year] The smallest amount of rainfall was recorded in 2011 of 510.6 [mm/year] The highest quantity of precipitation falls in May 2012 = 197.4 mm, 137.4 mm followed by

May 2011. The least amount of precipitation falling in February 2011 = 12 mm The maximum monthly = 40.8 mm in August 2009 Monthly Minimum quantity = 0 .4 mm in September and November 2011

0

50

100

150

200

250

Mon

th

January

Februa

ryM

arch

AprilMay June July

August

Septem

ber

October

November

Decem

ber

The

rain

fall

amou

nt 2

009,

201

0,

2011

, 201

2

2009 2010 2011 2012

Figure 1 The rainfall amount calculated for the 12 months of the years 2009, 2010, 2011, 2012

0

5

10

15

20

25

30

35

40

45

Month

Janua

ry

Februar

yMarc

hApri

lMay

June

July

August

Septem

ber

Octobe

r

Novem

ber

December

The

max

imum

am

ount

s of r

ainf

all c

alcu

late

d fo

r the

yea

rs 2

009-

2012

2009 2010 2011 2012

Figure 2 The maximum amounts of rainfall calculated for the years 2009, 2010, 2011, 2012 Emberger rainfall coefficient

22

100

ii mMPQ

−⋅

= (6)

P – average annual rainfall M – maximum average annual rainfall m-minimum average annual rainfall


34

Year Calculated values for Q2009 45,25 2010 59,80 2011 70,97 2012 53,19 2013 50,37

Figure 3 Maximum annual rainfall

Figure 4 The amount of rainfall in 2009-2013

Conclusions

We observed that annual average rainfall in 2012 is 721.9 [mm/year] with the highest value in the range examined.

The smallest value in 2011 of 510.6 [mm/year] followed by the precipitation of 2010 to 510.6 [mm / year].

The highest value of rainfall was recorded in 2009 by 708 [mm/year]. The smallest amount of rainfall was recorded in 2011 of 510.6 [mm/year]. The highest quantity of precipitation falls in May 2012 = 197.4 mm, followed by May 2011, with the value of 137.4 mm. The least amount of precipitation falling in February 2011, = 12 [mm]. The maximum monthly = 40.8 [mm] in August 2009. Monthly minimum quantity = 0 .4 [mm] in September and November 2011. Maximum amount of rainfall in 24 hours is an important feature of rainfall in Bucharest. The high frequency of these rainfall especially emphasizes the warm half of the continental climate of the country. They are generated by a high absolute humidity of the air, the more intense frontal activity and thermal convection, which stimulates the development of clouds and increase rainfall.

Number of days with precipitation> 0.1 mm during the year is not constant from month to month. In general, he has a variation that resembles with the annual course of monthly precipitation amounts. The months with the highest number of days with precipitation are May and


35

August, and the fewest days is recorded in September and February. Frequency the average yearly rainfall in the city of Bucharest exceed 110 days. References [1] Stănescu SV, Gavriloaie C. (2011) Aspects of the vegetation and fauna Colentina river route from Bucharest Romanian Ecoterra 27 [2] Stângă IC, Minea I., (2005) Considerations droughts in the Moldavian Plain, Romanian Journal of Climatology, 1 :367-377; Alexandru Ioan Cuza University Publishing Iaşi [3] Minea I, Stângă IC., (2004) Analysis of spatial variability of indices for assesing drought risks and disasters, Volume III :138-149 Book House Science, Cluj Napoca, ISSN 1584-5273 [4] Ghermec O., Ghermec C., Dubovan S., Rusănescu C.O. Improving the environmental performances of iron powders carburizing process in a methane-bearing atmosphere; Environmental Engineering and Management Journal October 2013, Vol.12, No. 10, 2019-2023 [5] Peel MC, Pegram GGS, McMahon TA. (2004) Global analysis of runs of annual precipitation and runoff equal to or below the median: run length International Journal of Climatology, 24, 807–822 DOI: 10.1002/joc.1041 [6] Barbu I, Popa I., (2004) Temperature and precipitation regime in 2003 in the Romanian forests Magazine forests, 4 [7] Vlăduţ A., (2010) Ecoclimatic indexes within the Oltenia plain Forum geographically. Studies and research in geography and environmental protection 9 : 49-56 49

http://onlinelibrary.wiley.com/doi/10.1002/joc.1041/abstract

http://onlinelibrary.wiley.com/doi/10.1002/joc.1041/abstract


STUDY OF THE FLUIDIZED BED HYDRODYNAMICS FROM THE ENERGETIC BOILERS USING DIFFERENT TYPE OF SOLID PARTICLES

PhD Daniela HOARĂ1, Prof. Gheorghe LĂZĂROIU2 1 Power Engineer Faculty, University “Politehnica” of Bucharest, Romania, [email protected] 2 Power Engineer Faculty, University “Politehnica” of Bucharest, Romania

Abstract: This paper presents the determination manner of the pressure drop, the minimum fluidization velocity and the floatation velocity of the solid particles in the fluidized beds, depending on the type of material used and on the size of the solid particles, making a comparison between the theoretical and experimentally determinations. Keywords: fluidizing, fluidization minimum velocity, pressure drop in the bed, floatation velocity of the particles

1. The fluidized bed - introductory notions

Definition

The fluidized bed is a system in which a gas, distributed by a distribution device (grid or jet nozzles), is expelled, from bottom to top, through a bed of solid particles, so that the particles float in the gas stream into a constant agitation.

Overview of fluidized bed combustion technology

The basic concept of the fluidized bed combustion technology consists in that in the combustion chamber is realized a hot bed of solid particles (e.g., coal, coal ash, gypsum, dolomite, calcium carbonate, silica sand, etc .) and is fluidized by an air flow which is introduced into the outbreak over to the bottom, keeping the bed in a sustentation state. Due to the layer homogeneity, the fuel particles are rapidly distributed in bed and are burned rapidly producing heat at elevated temperatures to generate steam, to heat water or for other technological purposes. Solid particles are continuously fed in layer and the ash which remains after burning is always removed to maintain a constant volume of solids in bed. Due to the rapid mixing of the particles layer respectively due to the higher combustion efficiency, the amount of unburned material layer is low. For a proper functioning of the layer, it is maintained in the temperature range 750°C÷950°C, the temperature at which the ash is soft and fine.

Fig. 1 The principle of fluidized bed combustion of the solid fuels

36


2. Aspects of fluidized bed combustion process

It is assumed that the combustion in the fluidized bed takes place in the same way as the combustion of a single particle because the carbon concentration in the fluidized bed combustion is about 1÷2%.

The fluidized bed combustion process for a single particle is performed in four stages: • heating and drying; • release and combustion of the volatiles; • primary fragmentation; • fuel combustion, secondary fragmentation and abrasion.

The Figure 2 shows in a schematized form this burning process.

Fig. 2 The stages succession for combustion of solid fuel particles [4]

So, it is necessary to analyze the combustion of a single particle before getting an overview of fluidized bed combustion process, after which may be quantified the results.

In literature there are many models for specific processes (hydrodynamics, heat and mass transfer, combustion) occurring in steam generators with fluidized bed combustion technology, but their use must be made with more caution.

3. The fluidized bed hydrodynamics

3.1 Determination of the pressure loss and of the minimum fluidization velocity

The fluidization state represents a biphasic dispersed system, one phase being constituted of solid particles and gas flowing amongst the particles (dispersion) and a bubble phase, made up from the gas phase and a small proportion of the solid particles found in sustentation, inside the bubbles. [5]

The fluidized bed, because of its structure and laws, is an intermediate state between two limit regimes: fixed bed and pneumatic transport. For this reason, its study is approached for particularizations on the two cases. There is a critical value of the velocity at which it starts to produce the expansion of a solid phase fraction, while the majority of the particles are still fixed. In

37


this case, the pressure loss of the gas in the layer is equal to the weight of the solid phase reported to the surface of the fluidization grid:

mfgsmfmf Hg)()1(p ⋅⋅ρ−ρ⋅ε−=∆ [Pa] (1)

where: Hmf [m] is the height of the layer at incipient fluidization conditions;

εmf [-] is the bubbles fraction in the layer at incipient fluidization conditions;

ρs, ρg [kg/m³] represents the density of solid and gas;

g [m/s²] is the gravity acceleration.

In order to determine the pressure loss in a fixed bed with solid particles of diameter dp and sphericity φs, it is used the Ergun's equation: [4]

ps

2

g32ps

3

2

dw175,1

)d(w)1(150

Hp

⋅φ⋅ρ⋅

εε−

⋅+⋅φ

⋅η⋅εε−

⋅=∆ (2)

where: η [N⋅s /m²] is the dynamic viscosity of the gas;

w [m/s ] is the gas velocity.

Replacing ∆p/Hmf from (1) in (2) it obtained a criterial relationship from which it can determine the minimum fluidization velocity:

2p3

mfsp3

mf2s

mf Re175,1Re1150Ar ⋅ε⋅φ

⋅+⋅ε⋅φε−

⋅= (3)

where: g

gs2g

3pdg

Arρ

ρ−ρ⋅

ν

⋅= is the criterion of Archimedes;

g

pp

dwRe

ν

⋅= is the criterion of Reynolds;

νg [m²/s] is the kinematic viscosity of the gas.

For small particles (Rep < 20) predominate the viscous forces, the equation (3) can be simplified, resulting the minimum fluidization velocity:

mf

3mfgs

2ps

mf 1g

150)d(

wε−

ε⋅⋅

η

ρ−ρ⋅

⋅φ= [m/s] (3’)

For larger particles (Rep > 1000) predominate the kinetic energy losses, the minimum fluidization velocity being approximated with:

g75,1d

w 3mf

g

gspsmf ⋅ε⋅

ρ

ρ−ρ⋅

⋅φ= [m/s] (3”)

38


If εmf or φs are unknown, can be made following approximations, valid for a variety of systems: [6]

1413mfs

≅ε⋅φ

and 111

3mf

2s

mf ≅ε⋅φε− (4)

After replacing in (3), (3’) and (3”) results:

η⋅

⋅ρ−ρ⋅=

1650g)(d

w gs2p

mf [m/s], if Rep < 20 (5’)

g

gspmf 5,24

g)(dw

ρ⋅

⋅ρ−ρ⋅= [m/s], if Rep > 1000 (5”)

In order to calculate the minimum fluidization velocity are given many relationship in the literature (See Table 1). [7]

Tab. 1 Calculation relationships of the minimum fluidization velocity obtained on the experimentally way

No. Authors Minimum fluidization velocity, wmf [m/s]

Validity domain dp [µm]

1 Baerg [ ]g

23,1mfsp )1(d

361,0ρ

ε−⋅ρ⋅⋅ Remf < 20 6 – 880

2 Miller, Logwinuk η

⋅ρ⋅ρ−ρ⋅⋅

g)(d00125,0

1,0g

9,0gs

2p -- 97 – 249

3 Leva 88,0

94,0gs

68,1p )(d

0079,0η

ρ−ρ⋅⋅ Remf < 10 51 – 970

4 Frantz η

⋅ρ−ρ⋅⋅

g)(d001065,0 gs

2p Remf < 32 46 – 305

5 Davis, Richardson η

⋅ρ−ρ⋅⋅

g)(d00078,0 gs

2p -- --

6 Pillai, Raya Rao η

⋅ρ−ρ⋅⋅

g)(d000701,0 gs

2p Remf < 20 58 – 1100

7 Baeyens 066,0g

87,0

934,0934,0gs

88,1p g)(d

0009,0ρ⋅η

⋅ρ−ρ⋅⋅ Remf < 10 --

3.2 The floatation velocity

The gas flow through the fluidized bed is limited on the one hand by the minimum fluidization velocity, wmf, and on the other hand by the entrainment of solid particles. When the solid particles are entrained in the layer, they must be recirculated or replaced with a fresh material to keep the operation equilibrium. The upper limit of the gas velocity is approximated by the floatation velocity or by the freefall velocity of the solid particles, which can be estimated from the equilibrium equation between the gravity force and the particle resistance force at the displacement of the gas stream:

39


gx

gsppl C3

)(dg4w

ρ⋅⋅

ρ−ρ⋅⋅⋅= [m/s] (6)

In (6) the coefficient Cx is experimentally determined. An alternative variant for determining the floatation velocity is to calculate the Cx coefficient for spherical particles, replacing in (6) and applying some correction factors.

For calculation of the Cx coefficient exist a lot of variants, the most commonly used being the method proposed by M. Leva: [3][8]

Re24Cx = for Re < 2;

6,0x Re5,18C = for 2 < Re < 500;

44,0Cx = for Re < 200.000 (7)

Kuni and Levenspiel propose the same method of calculation with small differences in formulas and in validity domains: [7]

Re24Cx = for Re < 0,4; 5,0x Re

10C = for 0,4 < Re < 500;

43,0C x = for Re < 200.000 (8)

4. Results

According to the theoretical method of determining the minimum fluidization velocity respectively the pressure loss in layer, there were determined its values depending by the variation of the solid particle diameter (Figures 3 and 4). There were taken into account several types of solid particles with following densities:

Coal ρs = 1545 kg/m³

Gypsum ρs = 2320 kg/m³

Dolomite ρs = 2872 kg/m³

CaCO3 ρs = 3320 kg/m³

40


6 33 59 86 112

139

165

192

219

245

272

298

325

351

378

405

431

458

484

511

538

564

591

617

644

670

0,0

0,2

0,4

0,6

0,8

1,0

1,2

Min

imum

flui

diza

tion

velo

city

[m/s

Particle diameter [µm]

CoalGypsumDolomiteCaCO3

Fig. 3 Variation of the minimum fluidization velocity (theoretically determined) depending by the

particle diameter

Conditions: ρg = 0,4 kg/m3, εmf = 0,45, ηg = 1,5×10-5 Ns/m2

6 33 59 86 112

139

165

192

219

245

272

298

325

351

378

405

431

458

484

511

538

564

591

617

644

670

0

100

200

300

400

500

600

700

Pre

ssur

e lo

ss [P

a]

Particle diameter [µm] Fig. 4 Variation of the pressure loss in layer depending by the particle diameter


Considering the calculation manner of the minimum fluidization velocity in the specific conditions of fluidized bed combustion (shown in the Table 1), below, there were graphically presented its values depending by the particle diameter modification, for each solid material taken into account.

41


0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

0,45

0 100 200 300 400 500 600 700 800Particle diameter [µm]

Min

imum

flui

diza

tion

velo

city

[m/s

BaergFrantzDavis, RichardsonPillai, Raya, RaoBaeyensLevaMiller, Logwinuk

Fig. 5 Variation of the minimum fluidization velocity depending by the particle diameter, determined

with calculation relationships proposed by various authors

Conditions: ρs = 1545 kg/m3, ρg = 0,4 kg/m3, εmf = 0,45, ηg = 1,5×10-5 Ns/m2

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

0,45


Min

imum

flui

diza

tion

velo

city

[m/s





42


0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

0,45


Min

imum

flui

diza

tion

velo

city

[m/s





0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

0,45


Min

imum

flui

diza

tion

velo

city

[m/s





In the Figure 9 it shows the variation of the floatation velocity depending by the particle diameter, in the specific conditions of the fluidized bed combustion, for the mentioned solids particles.

43


6 33 59 86 112

139

165

192

219

245

272

298

325

351

378

405

431

458

484

511

538

564

591

617

644

670

0

1

2

3

4

5

6

Floa

tatio

n ve

loci

ty [m

/s]



Fig. 9 Variation of the floatation velocity depending by the particle diameter


0

5

10

15

20

25

30

35

40

45

50

6 33 59 86 112

139

165

192

219

245

272

298

325

351

378

405

431

458

484

511

538

564

591

617

644

670


Rey

nold

s nu

mbe

r


Fig. 10 Variation of the Reynolds criterion depending by the particle diameter to determine the

floatation velocity


4. Conclusions

When determining the theoretical values of the minimum fluidization velocity respectively the pressure loss in layer depending on the particle diameter, using several types of solid materials, it resulted that: the minimum fluidization velocity values have an increasing trend with rising of the particle diameter, and also when the material used has an increasingly larger density. In terms of

44


pressure loss determined under the same conditions, its values increase in the same way as minimum fluidization velocity values.

Given the results of the calculations of minimum fluidization velocity, shown in the Figures 5, 6, 7 and 8, it is noted that the minimum fluidization velocity has an upward trend with increasing of the particle diameter. For the whole values range of the particle diameter, it recorded close values between the curves of Frantz, Davids, Richardson and Pilai, Raza, which also have a pronounced upward tendency. The curves of Baerg and Leva have maximum values and Baeyens have minimum values for whole range of values. Since the material is different, it changes its density, and thus, the minimum fluidization velocity is even higher with increasing of the used material density. Considering the minimum fluidization velocities found on the experimentally and theoretically way, for the considered solid materials, it appears that, for the experimentally determination, the minimum fluidization velocity values are lower than the ones resulted by the theoretical determination.

From the Figure 9 it is observed that the floatation velocities, calculated for different solid materials depending on the particle diameter variation, have higher values with increasing of the particle diameter and of solid material density, taking into account the values of the Reynolds criterion determined by the particle dimension size (shown in Figure 10).

REFERENCES

[1] V. Athanasovici, "Tratat de inginerie termică – Alimentări cu căldură. Cogenerare”, Ed. Agir, Bucureşti, 2010

[2] C. Neaga, "Tratat de generatoare de abur", Vol 1, Ed. Agir, Bucureşti, 2001 [3] C. Mihăilă, “Procese termodinamice în sisteme gaz-solid şi aplicaţiile lor în industrie”, Ed. Tehnică,

Bucureşti, 1982 [4] Gh. Ivănuş, I. Todea, Al. Pop, S. Nicola, Gh. Damian, “Ingineria fluidizării”, Ed. Tehnică, Bucureşti, 1996 [5] P. Basu, S. Frasier, "CFB Boilers - Design and Operations", Butterworth-Heinemann, 1991 [6] D. Kunii, O. Levenspiel, "Fluidization Engineering", John Wiley&Sons Inc., 1969 [7] S. N. Oka, "Fluidized bed combustion", Marcel Dekker Inc., New York, SUA, 2004 [8] V. Stojkovski, Z. Kostic, A. Nospal, “Determination of the terminal velocity for non-spherical particles”,

Termotehnika nr. 4, Belgrad, 1997

List of notations:

Notation Description UM NOx Nitrogen oxides - SF Fluidized bed -

Δpmf Pressure drop of the gas layer Pa εmf Bubble fraction in the layer under the incipient fluidization conditions - ρs Density of solids kg/m³ ρg Density of gas kg/m³ g Gravitational acceleration m/s²

Hmf Layer height under the incipient fluidization conditions m dp Particle diameter m φs Particle sphericity - η The dynamic viscosity of the gas Ns/m² w The gas velocity m/s Ar Archimedes criterion - Re Reynolds criterion - νg Gas viscosity m²/s

45


46

GENERAL METHODOLOGY OF WORKING WITH HVOF

INTEGRATED TECHNOLOGICAL SYSTEM

Eng. Valeriu AVRAMESCU1, Phd. Eng. Luminita Elena OLTEANU1, Phd. Eng. Loredana Theodora PAUN1, Phd. Eng. Raluca Magdalena NITA1,

Eng. Daniel BOBE1, Eng. Sebastian ROSULESCU1, Phd. Student Marius MANEA1 1 S.C. ICTCM S.A. – Mechanical Engineering and Research Institute [email protected]

Abstract: Article "General methodology of working with HVOF integrated technological system" aims to present some information about the thermal spraying process and all major stages of working with the integrated technological system for thermal spraying, created in the SC ICTCM -Mechanical Engineering and Research Institute, both in the case of metallic coatings for new pieces and general methodology for working with this system Keywords: HVOF installation, integrated technological system, thermal spraying process, spraying parameters, process structure of thermal spraying 1. Introduction In S.C. ICTCM – Mechanical Engineering and Research Institute - SA by project no. 614 SMIS code/NSRF: 12537 "Applied researches, technology and technological equipment for high strength thermal spraying by HVOF process used in industrial and medical applications", co-funded by the Regional Development European Fund, under the contract financing 270/ 27.10.2010, in the Operational Programme " Increasing Economic Competitiveness " (SOP IEC), Priority Axis 2 Research, Technological Development and Innovation, Operation 2.1.2- „High scientific level R&D Projects attended by specialists from abroad" with the participation of foreign experts was conducted an integrated technology system for thermal spraying by HVOF 2. HVOF thermal spraying process. Thermal spraying consists of a group of processes for making thin layers in which fine powders, metal or non-metal, is deposited in the molten state to form a coating layer with properties required of the of the applicability field. The process consists in continuously introducing a mixture of metallic powder and the axial high pressure gas in a combustion chamber. Thus, in the combustion chamber, result a high pressure to the combustion of the mixture of the flue gas – oxygen and especially through the expansion in the combustion nozzle located at the output, resulting a high-speed gas jet. As a result, the metal powder particles are accelerated to very high speeds which leads to layers of particles deposited with high density and very good adhesion. Characteristics of the HVOF thermal spraying process are briefly the following:

energy source is the gaseous oxygen and the fuel gas is ethylene, propylene or propane, and the liquid is kerosene; flame has the temperature of up to 2700 C and speeds up to 1600 m/s; the deposited material is powder with particle size of 5-45 μm; type of powder for deposition: generally are carbides with matrix of metal alloys speed of particles during deposition: 400-800 m/s; spray distance: 150 – 300 mm;

The features of layers deposited by HVOF process include superior characteristics to those deposited by other processes thermal deposition. They are:

high density: normally are obtained porosities lower than 2% and in special conditions, porosity of 0.2%;


47

high degree of adhesion to the base material; e.g. typical deposition of carbides such as the HVOF have the adhesion over 82 MPa, and the materials deposited by this process have significantly higher adhesion values than the same materials deposited by other thermal deposition methods in the atmosphere, such as plasma deposition;

high hardness; e.g. a carbide with wolfram and cobalt, with 12% wolfram has typical microhardness 1100 ... 1350 DHP300;

good fatigue resistance; depending on the chemical composition, the low temperatures of the deposited material by HVOF may produce coatings with good wearing resistance with excellent resistance to impact;

greater thickness of layer; HVOF coatings have the thickness of coated layer greater than plasma coatings, by combustion or by wire to the same material, due to the effect of flattening the previously deposited layer by increased particle impact at high speed; thus, the thickness of layers of wolfram carbides can be up to 6.4 mm;

excellent wear resistance; HVOF deposition are resistant to the wear caused by sliding friction, friction, erosion or cavitation depending on the material and the parameters of selected process;

superior corrosion resistance; high density and metallurgical properties of layers deposited by HVOF confer resistance to corrosion effects, including hot corrosion, oxidation and corrosion of acid and alkaline environments;

very good finishing of the covered surface; HVOF coated surfaces are smooth and can be used as such in many applications, can also be machined, grinding, lapping, honing or super-finished to applications that require precise tolerances and very good surface quality.

3. The general structure of a HVOF coating technological process In general, a metal coating is in one of two situations: applied in the mass production for new parts or used in the reconditioning process of existing parts. In the first case all necessary technological parameters are known to meet the technical requirements of respective pieces, the carried activities being only those of process control. If it is necessary the development of a new application, in which are known only to the quality requirements of the future piece are needed research/development activities on both materials that can be used to cover and parameters of the technological process used. This is the case of this project, in which is necessary to conduct researches to achieve coatings by HVOF process to meet the requirements of each application separately. In figure 3.1 is presented the methodology of research/development of new metallization applications, valid for HVOF process. In general, the structure of a thermal coating technology process through HVOF process (High Velocity Oxygen Fuel) is: • Prepare surfaces for coating; techniques commonly used for this are the following:

- cleaning the surface; - formation of the substrate; - activating the surface; - masking.

• HVOF deposition of the material layer on the support material; • Apply treatments/technological operations after depositing material layer; techniques commonly used for this are the following:

- thermal treatment, which can be: - electro-magnetic treatment; - treatment in an oven; - hot isostatic pressing (HIP); - remelting with flame;

- impregnation, which can be: - coating of the surface/seal with organic substances; - coating of the surface/seal with inorganic substances;


48

- finishing, which can be: - grinding; - polishing and lapping;

Fig. 3.1 – Methodology for the elaboration of new coatings

4. General Methodology of working with the HVOF technological integrated system In the HVOF technological process one of the most important steps is cleaning the workpiece surface to remove impurities such as rust, paint residues. This step is performed using a blasting booth. Blasting is the process of cleaning or finishing through blowing abrasive of metal surfaces. One of the materials used to blasted is corundum, which is blown by means of a jet compressed air. Corundum is a mineral classified as hardness 9, second after diamond on the Mohs scale, because the Moissanite mineral with hardness 9.25 (very rare in nature) is not considered. From the point of view of the chemical composition is an aluminum oxide with the formula Al2O3. Color is very varied depending on the existing impurities in the crystal. The steps of the blasting operation are the following: - is started the compressor's dryer and is waiting until the indicator reaches on green zone of the

scale; - is adjusted the compressor’s working pressure from 6 to 7 bars; - is started the compressor and is waiting until the operating pressure is reached in the

compressed air system; - is supplied the blasting booth with air and is adjusted the working pressure at 6 bar from the

resident air regulator; - is started the blasting booth, the pieces to be blasted are putted in the cabin, is pushed the

compressed air filling pedal and is blowed the corundum over the pieces surfaces until they become cleaned;


49

- are visually inspected the blasted pieces and is measured the surface’s roughness; - if the blasted surface quality is adequate, the air supply is interrupted and blasting booth is

stopped; After preparing the pieces through the blasting process, the thermal spraying process is achieved by the HVOF process. For this, perform the following operations: - pieces for spraying are fixed in clamping brackets mounted in handling devices for pieces with

horizontal shaft (type lathe - between centering peaks mounted in the universal headstock and in tailstock) and vertical (rotary table – with clamps on the plateau with T channels);

- is started the electrical installation for driving the manipulation devices, is switching on the type of device used and is started adjusting the corresponding speed to the type of HVOF coverage; is checked the centering of the fixed pieces in the handling device in question; if the operation is properly is stoped the handling devices;

- is established on the mobile console of the robot FANUC (teach pendant) the moving program properly for sprayed pieces, including movement speed and number of passes properly for thickness layer which will provide, and spray distance specified; is checked the program in operation mode T1 and AUTO (closes the spray booth door which will be locks by the safety module "open door");

- is started the PLC control cabinet; - is started the feeding/dosing powder system and are filled the two cans of the system with

adequate powder properly for cover, in equal amounts (weighed with a precision analytical balance) depending on the specific consumption/min (tested depending on the speeds dosage discs from prescription of spray);

- is started the pistol cooling system, is checked the level and is adjusted the temperature of the cooling water; are opened the water valves flow/return;

- are opened the cylinders of oxygen and nitrogen: is adjusts the working pressure 20 bar on the oxygen supply system regulator is adjusts the working pressure 6 bar on the nitrogen supply system regulator

- is ensured sufficient kerosene in the recipient; - is adjusted to 6 bar pressure for the compressed air used for cooling sprayed parts from the air

regulator found in the gas control cabinet. After all the above steps have been performed, can be started the HVOF operators console command: - is unlocked the emergency stop button on the front panel of the console; - is inserted the key and turn the power switch on the control panel to the ON position and is

waiting for the computer to start the process and to display the startup menu display command console;

- the red button "fault" for errors on display will flash warning that there are some errors; - is setting the program language (ie English), and are admitted errors using the touchscreen

"acknowledge". - are checking on the display the parameters of the cooling gun system, supply kerosene, supply

oxygen, nitrogen, compressed air and possible gas leaks and kerosene; - are established the technological parameters of the specific spray recipe: the pressure and the

flow rate of oxygen, nitrogen, kerosene, type of powder used, feeding/dosing powder system’s speed; the spray recipe is saved with a specific name;

- is pressed the button „Power On”; - is closed the spray booth door and press the button "Door locked"; lights the lamp "Door locked"

and the door is locked by the user’s safety system module; - is pressed the button "User safety" and if module safety system is activated, will light the

indicator "Customer safety"; - is started the emissions filter system from the button with three positions on its switchboard (1

emissions filtration installation + inside air introduction system, 2 emissions filtration installation, 3-OFF;

- is started from the specific menu, the compressed air supply of pieces' cooling nozzle; - is pressed the button "Ignition" and is primed the flame of the spray gun;


50

- is checked the priming mode (no failures), color (should be blue), focus and continuity of the flame (flame must be continuous without interruption);

- is pressed the button "Powder Start" then the button "START" and the jet is primed and is checking the focus (jet must be focused and otherwise modify the flow of nitrogen from two feed powder) and its continuity (jet must be continuous without interruption);

- is started appropriately handling device and adjust the speed required; - is started the robot program in operation mode AUTO; - after spraying is pressed the button "Stop Powder", "STOP"; - is waiting about 15 min for cooling pieces then is stopped the feeding of cooling nozzles and

emissions filtration system; - is stopped the device for handling pieces, from the electrical installation of drive devices; - is pressed the button "Door unlocked" and can enter in the spray booth; - is rotated the key in the power switch on the control panel to the OFF position; - are removed the pieces from the handling device and are controlled the parameters of the

sprayed layer: thickness, hardness, adhesion, porosity, metallographic structure.

5. Methods of characterization and control of HVOF deposited layer In general the HVOF deposited layers are characterized by strong links with the base and a good quality and porosity of the surface. Thus, for wolfram carbide can be achieved resistances to separation of 90 MPa with porosity of less than 1%. The characterization of deposited layers by metal coatings is important for: research/development activities for a new product or quality control in production. The easiest way to control the quality of the surface is a careful visual observation of it. Such a method allows the detection of defects such as incomplete coverage of the entire surface or superficial cracks. More advanced methods for the surface investigation are those of analysis of the microstructures that are made by scanning electron microscopy (SEM), X-ray diffraction (XRD), electron microscopy by transmission (TEM), porosimetry by inclusion of mercury (MIP) or other techniques. The properties of the metal coating cause its behavior during use. The best test is done under conditions that simulate actual conditions of use of the piece. The mechanical properties such as microhardness, tensile strength and modulus of elasticity, wear-resistance are often determined. Thermophysical properties and in particular the thermal conductivity, usually determined by measuring the expansion to 300 K, specific heat and diffusivity are frequently tested. These tests are frequently accompanied by tests of resistance to thermal shock. Magnetic and electrical properties of the coating are frequently tested. Non-destructive tests such as the use of thermal or acoustic waves have been introduced to characterize the quality of the coating. Finally many properties are closely interlinked so it is possible to measure a property by determining another. An example for determining of a property by another's measuring is correlation between anisotropy of NiCr coatings, electrical conductivity and modulus of elasticity. These properties interlinked helps to reduce the number of tests required. The methods for characterization of metal coatings are the following: 1) Methods for characterization of the microstructure: chemical analysis; crystallographic analysis;

analyzes of the microstructure; 2) Methods for characterization of mechanical properties: determination of the adhesion;

determination of the hardness and microhardness; determination the modulus of elasticity, friction resistance, ductility; properties related to fracture mechanics of the metal coatings; determination of the resistance to friction and wear; determination of residual stresses;

3) Methods for characterization of physical properties: determining the thickness, porosity and density; determining thermophysical properties; determining resistance to thermal shock;

4) Methods for characterization of electrical properties: determination of electrical conductivity; determination of dielectrics properties; determination of electron emission from surfaces; determination of wet corrosion; determining gaseous corrosion (hot gas);

5) Methods for characterization the quality of the metal coatings: acoustic methods; thermal methods.


51

6. Hydraulic and pneumatic applications HVOF process has extensive applications in highly various domains, but it is important to specify the particular applicability of the HVOF deposition both in the domains of the hydraulic components and the pneumatic. Special properties required by the environment and operating conditions are ensured by HVOF process for the components of hydraulic or pneumatic cylinders, valves, pumps, taps and other hydraulic/pneumatic components which can equip building machinery, forestry machinery, agricultural machinery, equipment and industrial installations etc. In the case of a hydraulic or pneumatic cylinder, there are surfaces that can be deposited in different ways to obtain the functional properties of the cylinder - deposits can be specific for rod or pipe, or piston, or cap but their combination and the final result provide getting a high quality product with very good durability, extremely reliable in operation. The HVOF depositions give them specific properties both at the manufacturing stage, as new product, but and as reconditioning able to provide at least the initial quality of the remanufactured parts. Increased service life, is a considerable advantage but and the providing of special tribological properties, or adherence or porosity and wear resistance are equally important. Finally, an important aspect is the opportunity to research obtaining of a specific deposition, a specific requirement, or a plurality of requests, the process can be optimized. 7. Conclusions

By the project "Applied researches, technology and technological equipment for high strength thermal spraying by HVOF process used in industrial and medical applications", was developed a technological system - prototype - technological equipment and laboratory equipments - which allows performing of the applied researches to achieve high mechanical strength metal coatings, thermal, anticorrosive on materials used industrial or medical applications using HVOF process (High Velocity Oxygen Fuel). Also the conditions of market access were created for the new technological system by conducting theoretical and applied researches of the optimal technological parameters for solving practical requirements of industry and the production of medical equipment. Characteristics of the HVOF thermal spraying process are briefly the following:

energy source is the gaseous oxygen and the fuel gas is ethylene, propylene or propane, and the liquid is kerosene;

flame has the temperature of up to 2700 C and speeds up to 1600 m/s; the deposited material is powder with particle size of 5-45 μm; type of powder for deposition: generally are carbides with matrix of metal alloys speed of particles during deposition: 400-800 m/s; spray distance: 150 – 300 mm;

REFERENCES

[1] Technical Documentation GTV Coating System HVOF-MF-K 1000, Project ICTCM, 662.013 [2] "Study regarding the theoretical determination of specific technological parameters for HVOF process on application" project no. 614 SMIS code/NSRF: 12537, contract no.: 270 / 27.10.2010, project "Applied researches, technology and technological equipment for high strength thermal spraying by HVOF process used in industrial and medical applications -“TEHVOF” ", Sectoral Operational Programme " Increasing Economic Competitiveness ", Priority Axis 2,Operation 2.1.2- „High scientific level R&D Projects attended by specialists from abroad”, co-funded by the Regional Development European Fund, [3] “Research on identifying applications and parameters specific to HVOF process - Study on the determination of spray materials used in each case”, project no. 614 SMIS code/NSRF: 12537, contract no.: 270 / 27.10.2010, project "Applied researches, technology and technological equipment for high strength thermal spraying by HVOF process used in industrial and medical applications -“TEHVOF” ", Sectoral Operational Programme " Increasing Economic Competitiveness ", Priority Axis 2,Operation 2.1.2- „High scientific level R&D Projects attended by specialists from abroad”, co-funded by the Regional Development European Fund, [4] *** Thermal spray materials guide, SULZER – METCO [5] *** Surface technology, H.C.STARK [6] *** HVOF and thermal spray powders, DELOR


52

CABIN HEAT REMOVAL FROM PARKED CARS Assoc. Prof. Ph.D. Adrian CIOCANEA 1 , Lect. Ph.D. Dorin Laurenţiu BUREŢEA 1

1 University Politehnica Bucharest, [email protected]

Abstract:The paper presents a solution for designing an intelligent and modular solar energy system for heat removal from parked car cabins. We propose a ventilation system composed of two pairs of cross flow fans, one placed under the car roof cabin between the steel plate and the indoor insulation and the second under the rear shelf of the back seats. The cabin was exposed to the sun radiation (600-800 W/m2) with no wind. Indoor temperature and humidity were measured with no ventilation. The data was used to design the cross flow fans. The air flow rate needed for an efficient ventilation was calculated at 0.02 m3/s, a value compatible with other results in the literature.

Keywords: car ventilation, solar energy, cross flow fan

1. Introduction

The increase of the air temperature inside car cabins, especially when parked under intense solar radiation, has some negative impact such as: low thermal comfort and some health risk for the passengers, increased fuel consumption when restarting the air conditioning for reducing the indoor temperature and lowering the quality of the cabin materials like plastics, foams or artificial leather, rubber, synthetic fiber etc.

Concerning the health risk for the passengers, research was performed in order to highlight the risk of human exposure to volatile organic compounds (VOC) especially in the case of new cars [1]. Even if some studies state that “the smell of the new car”wears off in a matter of weeks or months [2], the process of VOC elimination, also responsible for the indoor air quality, is not confirmed. For example, the toluene and xylene concentration inside cars declines from 200 to 60 μg/m3 and from 250 to 30 μg/m3 respectively in 20 days but these VOCremain present [3]. Also, research shows that for some VOC the concentration varies in time and is dependent on indoor temperature, humidity, ventilation efficiency, age of the car (where poor sealing allows exhaust gases to enter the cabin)and other conditions such asclimate etc. In close relation with the above, we know that in an automobile of 1000 kg weight, about 100 kg consists of plastics –50% of the total internal components including safety subsystems, doors and seat assemblies. Also, 13 types of polymers are used in an automobile - 66% of these are polypropylene (32%), polyurethane (17%) and PVC (16%) [4]. Statistics estimate that people spend about 7% of their day commuting between home and workplace [5], or even more if vehicle’s cabinis in fact their workplace(the case of professional drivers). Hence automobile drivers are exposed to organic hydrocarbons. Concentrations reported in the passenger cabins are about 13 to 560 μg/m3 for benzene, 33 to 258 μg/m3 for toluene, 20 to 250��μg/m3 for xylene and 3 to 23 �μg/m3 for trimethylbenzene [3]. The accepted values for the environment are 2–150 μg/m3 for toluene and 5–20 μg/m3 for benzene (European Chemicals Bureau, 2003 a,b; World Health Organization, 2000). For new cars, studies [6-7] report average concentrations values of 11.8 μg/m3, 82,7μg/m3, 21,2 μg/m3 and 89,5 μg/m3

for BTX - benzene, toluene, o-xylene and m,p-xylene respectively. In used cars, BTX concentration values are higher and relevant deterioration of data was reported for more than 11.000 km.

Concerning the passenger thermal comfort, some research was performed in order to evaluate the interaction between the human body and indoor cabin conditions. For this, a “human body defragmentation”in 16 static elements was proposed [9] for which mass and heat exchange was measured between these elements and cabin components. It was reported that nonuniform air and temperature distribution are the cause for local high discomfort for passengers. Other studies propose intelligent ventilation of the cabin when the car is parked [10]. For some case studies


53

windshields are consideredas the main gate for solar radiation access and for this hypothesis some extreme heat surfaces were identified in order to be first/intensely ventilated. Still, existing studies do not provide clear results regarding efficient solutions for cabin ventilation, since experimental results are not convergent with theoretical models [11]. Concerning the fuel consumption it is known that when restarting the air conditioning system over a parked period under high solar radiation, the car engine will request more fuel than under normal conditions (related to rated engine temperature). Hence high engine fuel consumption will be registered untilindoor conditions becomesuitable for passenger comfort. The above reasons constitute a good motivation for studying an efficient ventilation system also for reducing house effect in the cabin.

According to the above assumptions, we propose an original solution for cabin heat removal from parked cars by using an intelligent solar modulated system equipped with crossflow fans.

2. The ventilation system For the ventilation of passenger cabins some solutions propose independent units with

simple structuresuch as lateral windows fans [12-14] or roof window fans [15] powered by solar photovoltaic panels. Another solution is given by considering complex ventilation systems included in the ventilation structure of the cabin. For example some systems are placed on the roof of the car [16-17] in the exterior as shown in figure nr. 1 a, b or inside the car [7-9] as shown in figure nr. 2 a,b,c; the case “c”pictures a ventilation through the car trunk.

The solutions for ventilation systems are only to some extent compatible with theoretical results as presented in the first chapter. This is because most of the ventilation solutions are focused just on exhausting the heat air form the car cabin neglecting the indoor region where temperature is rising excessively–for example the front shelf. On the other hand, theoretical studies depend on some special border conditions in order to provide numerical solutions –for example the sun azimuth. Due to such a hypothesis, some theoretical results are not suitable to be used for selecting practical solutions –for example some studies consider the high temperature region to be on front shelf, other results consider this region as between the front and back seats.

a. b.

Fig. 1 External vehicle ventilation units a. Top window cabin unit [16]; b. Air extraction unit [17]

ISSN 1453 – 7303 “HIDRAULICA” (No. 3/2014)

54

Magazine of Hydraulics, Pneumatics, Tribology, Ecology, Sensorics, Mechatronics

a. b. c. Fig. 2 Internal vehicle ventilation systems

a.b. Top cabin system [18-20]; c. Trunk system [21]

According to these conclusions one has to decide the optimum position and size of the fans and to design the ventilation system in terms of electrical and operating demands.

The present paper presents a solution to these problems by considering that the best method

to remove the car cabin heat is to avoid, as much as possible, the rise of the indoor temperature. Hence one propose a modular ventilation system. Two cross flow fans are to be positioned on the top front of the cabin–under the car roof cabin between the steel plate and the indoor insulation - and the other two under the rear shelf of the back seats. The main idea is to avoid temperature rise by ventilating the car roof - which is the highest surface exposed to the sun –and at the same time to remove the indoor heat through the rear of the cabin using the trunk in the same conditions as before. The positions of the fans and the system are presented in figure nr. 3. A Ford Mondeo cabin was considered for the preliminary experimental research i.e. monitoring the indoor parameters –temperature and humidity–and outdoor parameters –air temperature and external car roof temperature.

a.

ISSN 1453 – 7303 “HIDRAULICA” (No. 3/2014) Magazine nics

55

of Hydraulics, Pneumatics, Tribology, Ecology, Sensorics, Mechatro

b. c.

d. e.

Fig. 3 The proposed ventilation system

a. Structure of the ventilation system; b. Front cross flow fan (A); c. Roof cabin

extraction unit (B);d.Rear cross flow fan (C); e. The trunk extraction unit (D)

3. Experimental research

The cabin was exposed to the sun radiation –600-800 W/m2- with no wind. Indoor temperature and humidity were measured with no ventilation. In the cabin, the temperature and humidity were measured at the level of the driver; the outdoor thermometer for measuring the temperature of the steel roof was positioned at 5mm distance from it. The measurements had a 15 min frequency. Table nr. 1 shows the results. The data corresponds to the values of the indoor temperature provided by the literature –(60-65) 0C –which is reached in about 70 min. after the moment of parking the vehicle. The gap between indoor, outdoor and roof steel temperature is presented in figure nr. 4.

Table 1. Temperature and humidity inside the car cabin

Time T out

[0C] Tin

[0C]T teel s[0C]

urel [%]

H [W/m2]

1230 40.0 32.8 40.0 35.0 728

1245 40.2 34.9 46.6 31.3 738

1300 40.6 45.2 66.0 22.4 746

1315 40.8 51.5 66.0 18.1 788

1330 40.9 56.5 61.0 15.5 785


56

1345 41.5 59.1 62.5 14.6 790

1400 42.7 61.0 64.3 14.1 780

1415 42.7 61.0 62.7 13.8 752

1430 43.4 64.3 63.6 13.6 747

1445 43.6 64.8 64.6 13.4 727

1500 45.1 65.6 66.3 13.4 714

1515 45.8 65.9 66.3 13.4 704

1530 46.7 65.8 66.3 14.0 688

Fig.4 The gap between tindoor , toutdoor and tsteel

It can be observed that after 60 minutes the gap is 4.5 0C and after 90 minutes the gap remains constant at about 2-3 0C. It is also clear that the ventilation system must start after about 25 min after parking the car.

In order to design the cross flow fan it is necessary to evaluate the air velocity in the channel (see figure 3.b). Using the average values of the data presented in table nr. 1 we consider that all the heat transferred from the roof to the channel is removed through section B. As the physical model is similar with that of plane solar heat collectors one can use the same mathematical approach: the roof channel describes a plain solar heat collector with internal flow. The dimensions are L x l x b = (1,3 x 1 x 0,03) m, where “b”is the diameter of the fan rotor and has to meet the ventilation requirements. If the efficiency of the installation is⎜c = 0,5, assuming a good evacuation of the heat, velocity value and the air flow through section B can be calculated. Using the classical formula for the heat flux:

Q = ©air xcpair l x b x v x (t in - tout) 1

and: ⎜c = Q/ (L x l x H), 2

we obtain the value for air velocity “v”. For the present case study, if average values are H = 750 W/m2and (t in - tout) = 200 C, the velocity average value is v = 0,65 m/s and the air flow rate is 0,02 m3/s. The obtained values are compatible with recent theoretical research [21] where the authors obtained an air flow rate of 0,023 m3/s for the case of heat removing from a car cabin by using a numerical method (thesestudies were performed between the same time of the day). As the results are similar both for the roof channel (experimental) and cabin (theoretical from the literature) we propose the same dimensions for the rear cross flow fans of the cabin.


57

Figure nr. 5 shows an example of an available the cross flow fans. The technical solution for the case study consists in two pairs of fans with a single motor for each pair.

Fig. 5 Cross flow fan (drotor=30 mm; A=160 mm; B=170 mm; C = 194 mm; Rated voltage =12 V; Rated current = 0,2 A; Speed

=3,200 RPM; Max. Pressure = 1.5 nnH2O; Air Flow = 0.8 m2/min; Noise = 37 dB; Weight = 230 g)

The fans are selected for parallel operation, doubling the available flow rate. If longer rotors (A) are used, more air flow can be obtained. The two ventilation modules are powered by solar photovoltaic cells positioned on the roof of the auto vehicle and assisted by an automation system –as presented in figure nr. 6 -providing variable rotating speed for the fans according with the indoor temperature and the external temperature of the steel roof –related with the solar radiation.

Fig. nr. 6 Automation system

1. Photovoltaic cells; 2. DC to DC Converter – Switched Mode; 3.Temperaturesensors; 4.Humidity sensors; 5.Car Battery; 6.Automation Unit; 6.1.Measurement Unit; 6.2.Microcontroller Unit; 6.3.SMPS

(Switched Mode Power Supply) Variable Speed Fan Motor Driver; 7. Fan Motor 1; 8. Fan Motor 2.

As the humidity is decreasing in the cabin car during the parked period, a method for improving the passenger comfort after restarting air conditioning is needed. Further research will be focused on controlling humidity vs. temperature in the cabin car.

The presented system has low economic impact on vehicle price. From an economic point of view, the cost of the system is approx. 250 Euro since the double cross flow fans cost is 100 Euro.


58

Conclusions

The paper presents a solution for designing an intelligent and modular solar energy system for heat removal from parked car cabins. We propose a ventilation system composed of two pairs of cross flow fans, one placed under the car roof cabin between the steel plate and the indoor insulation and the second under the rear shelf of the back seats. The cabin was exposed to the sun radiation with no wind. Indoor temperature and humidity were measured with no ventilation. For a 750 W/m2 average solar radiation the air flow rate needed for an efficient ventilation was calculated at 0,02 m3/s, a value compatible with other results in the literature.From an economic point of view, the cost of the system is approx. 250 Euro since the double cross flow fans cost is 100 Euro. Further research will be focused on controlling humidity vs. temperature in the cabin car.

REFERENCES [1] Mandalakis M., Stephanou E. G., Horii Y., Kannan K., 2008. Emerging contaminants in car interiors:

Evaluating the impact of airborne PBDEs and PBDD/Fs. Environmental Science and Technology, 42(17): 6431–6436.

[2] Johansson I., 1999. The role of volatile organic compounds in the assessment of indoor air quality.Ph.D thesis.Institute of Environmental Medicine, KarolinskaInstitutet, Stockholm.

[3] Schupp T., Bolt H. M., Jaeckh R, Hengstler J G, 2006. Benzene and its methyl-derivatives: Derivation of maximum exposure levels in automobiles. Toxicology Letters, 160(2): 93–104.

[4] http://www.plasticsconverters.eu/organisation/division / automotive -cit. on 30.4.2010 [5] Kadiyala A., Kumar A., 2012. Development and application of a methodology to identify and rank the

important factors affecting in-vehicle particulate matter.Journal of Hazardous Materials, 213-214: 140–146.

[6] Moriske, H.-J., 2002. Luftqualitaet in Innenraeumen von Verkehrsmitteln. Bundesgesundheitsbl Gesundheitsforsch Gesundheitsschutz 45, 722–727.

[7] Faber, J., Brodzik, K., Golda-Kopek, A., Lomankiewicz, D., 2013, Benzene, toluene and xylenes levels in new and used vehicles of the same model. Journal of Environmental Sciences 2013, 25(11) 2324–2330. [8]World Health Organization, 2000.Air Quality Guidelines for Europe.WHO regional publications, European series, No. 91, ISSN 0378- 2255.

[9] Kaynakli, O., Kilic, M., 2005, An investigation of thermal comfort inside an automobile during the heating period, Applied Ergonomics 36 (2005), pp. 301–312.

[10] Huang, K.D., Tzeng S-C, Ma, W-P, Wu, M-F, 2005, Intelligent solar-powered automobile-ventilation system, Applied Energy 80 (2005) 141–154.

[11] Marcos, D., Pino, F.J., Bordons, C., Guerra, J.J., 2014, The development and validation of a thermal model for the cabin of a vehicle, Applied Thermal Engineering 66 (2014), pp. 646-656.

[12] Wolfe, R.P., Callaghan, J.K., Pidgoen, S., 1990, Solar Powered Ventilator, U.S. Patent 4,899,645. [13] Biancone, M.R., 2002, Ventalation system for an interior of the motor vehicle, U.S. Patent 6,435,961. [14] Lesle, M.J., 2011, Through glass ventialtion, US 2011/0151761 A1. [15] Fermont, R., 1989, Ventilation device, U.S. Patent 4,800,803. [16] Smith, M.A., Smith, C.Y., 2007, Vehicle roof mounted air extraction unit, GB 2429518 A. [17] Amrhein, W., Scharf, F., Bauer, W., 1988, Device for ventilating vehicle compartments ,EP 0256313 A2. [18] Clenet, A.J.-M., 1992, Vehicle vent, U.S. Patent 5,081,912. [19] Snow, C.E., 2004, Solar powered heating and ventilation system for vehicle, US 6,692,130 b1. [20] Cui, Z., 2012, Vehicle parking idling solar air intercharger, CN 201220435932. [21] Leong, J.C., Tseng, C.-Y., Tsai, B.-D., Hsiao, Y.-F., 2010, Cabin Heat Removal from an Electric Car,

World Electric Vehicle Journal Vol. 4 - ISSN 2032-6653.

http://www.plasticsconverters.eu/organisation/division%2520/


59

INTEGRATED TECHNOLOGICAL SYSTEM FOR THERMAL SPRAYING

BY HVOF PROCESS

Phd. Eng. Theodora Loredana PAUN1, Eng. Valeriu AVRAMESCU1, Phd. Eng. Raluca Magdalena NITA1, Eng. Daniel BOBE1, Eng. Sebastian ROSULESCU1,

Phd. Eng. Elena Luminita OLTEANU1, Phd. Student Marius MANEA1

1 SC ICTCM – MECHANICAL ENGINEERING AND RESEARCH INSTITUTE, [email protected] Abstract: The paper "Integrated Technological System for thermal spraying by HVOF process" presents technological system aims, system that includes both technological equipment and laboratory equipment. It can thus perform applied research to achieve high strength metal coatings, thermal, corrosion on materials used in both industrial and medical applications using HVOF process. It is also possible to create the conditions of market access for new technological system by conducting theoretical and applied research of the optimal technological parameters for solving practical requirements of industry and the production of medical equipment. Keywords: HVOF, technological system, technological parameters, thermal spraying, industrial robot 1. Introduction.

In S.C. ICTCM – Mechanical Engineering and Research Institute - SA by project no. 614 SMIS code / NSRF: 12537 "Applied researches, technology and technological equipment for high strength thermal spraying by HVOF process used in industrial and medical applications", co-funded by the Regional Development European Fund, under the contract financing 270 / 27.10.2010, in the Operational Programme " Increasing Economic Competitiveness " (SOP IEC), Priority Axis 2 Research, Technological Development and Innovation, Operation 2.1.2- „High scientific level R&D Projects attended by specialists from abroad" with the participation of foreign experts was conducted an integrated technology system for thermal spraying by HVOF process. 2. HVOF thermal spray process. Thermal spraying is made up of a group of processes for making thin layers in which fine powders, metal or non-metal, is deposited in the molten state to form a coating layer with properties required of the user. The method includes continuously introducing a mixture of metallic powder and axial gas pressure in a combustion chamber. In the combustion chamber results a high pressure from the combustion of a mixture from gas - oxygen, and by expansion in the combustion, which is located at the output, results the high speeds of the gas flow. As a result, the metal particles from the powder are accelerated at a high speed which results in layers of particles made with high density and good adhesion. The characteristics of HVOF thermal spray process are briefly the following:

energy source is oxygen in gaseous form and the fuel gas is ethylene, propylene or propane, and the liquid is kerosene;

the flame has a temperature of up to 2700 C and the speeds up to 1600 m / s; the deposited material is a powder with particle size of 5-45 μm; type of the deposited powder is: carbide with metal alloys matrix; particle velocity during deposition: 400-800 m/s; spray distance: 150 – 300 mm;

Charasterics of the deposited layers by HVOF process are superior characteristics toward to those deposited by other processes of thermal deposition. They are:


60

high density: is obtained, generally less than 2% porosity and special conditions up to 0.2% porosity;

high adhesion with the base material; for example, the fuel HVOF deposition are typically above 82 MPa adhesion, and other materials made by this process have significantly higher adhesion values than the same materials made by other methods of thermal deposition atmosphere, such as plasma deposition;

high hardness; eg tungsten and cobalt carbide, with 12% tungsten has a typical microhardness about 1100 ... 1350 DHP300;

good fatigue resistance; depending on the chemical composition, the low temperatures may cause a good wearing resistance and a high impact resistance of the deposited material by HVOF process;

it has a greater thickness; the layers coated by HVOF process hahavea greater thikness than plasma coatings by combustion or by wire to the same material, due to the effect of flattening the rule previously filed by increased particle impact at high speed; thus, the thickness of layers of tungsten carbides can be up to 6.4 mm;

excellent wear resistance; HVOF coatings are resistant to the wear caused by sliding friction, abrasion, erosion or cavitation depending on the material selected and the process parameters;

superior corrosion resistance; due to the high density and metallurgical properties of coatings deposited by HVOF confer resistance to corrosion effects, including hot corrosion, oxidation and corrosion of acid and alkaline environments;

good finish surface covered; HVOF coated surfaces are smooth and can be used as such in many applications, can also be machined, ground, lapping, honing, lapping or super-finished for applications that require precise tolerances and a high quality surface.

3. HVOF laboratory. Main components: features and functionality The laboratory is a technological system - prototype - which allows applied research in order to achieve high strength metal coatings, thermal, corrosion on used materials, industrial and medical applications using HVOF process, for which they were provided the following equipment and accessories: blasting cabin, compressor, thermic spray cabin, parts handling devices (horizontal axis and vertical axis connected to the exhaust system and exhaust filter) FANUC robot M-20i model, a filtration system exhaust and ventilation ducts, technical gases and distribution networks, security system for containers and HVOF accessories, thermal spray equipment. 3.1 Vacuum Sandblaster acquired by ICTCM is a FERVI-0687 and has the following

characteristics and equipments: • Chamber dimensions ………………………………………… 1200x600x600 mm; • Operating pressure …………………………………………… 6,5-7,5 bar; • Air consumption………………………………………………. 630 l/min; • Ø gun nozzles (mm)………………………………………….. 6-7 mm; • Filtration rate …………………………………………………. 5 micron; • Operating power ……………………………………………… 1200 W/230 V; • Power supply …………………………………………………. 230v/ 50 Hz; • Mass……………………………………………………………. 147 kg; • External dimensions …………………………………………. LxlxH=1220x910x1740 mm; • Sandblasting gun with sand jet; • Side doors an both parts and access on the superior part; • Illuminating system at the inside with blasting protection; • Exhausting system and residual dust filtering; • Closed system with retrieving, filtering and recycling of the abrasive material; • Separatinf filter for water; • Pedal with pneumatic command;


61

Fig. 3.1 Integrated technological system for thermal spraying by HVOF process The surfaces of parts that will be coated by HVOF process, thay are blasted in order to remove oxides, slag, and to obtain rough to ensure good adhesion of deposited dust layer. The sandblasting consists of shelling the surface with abrasive particles (corundum) of various grain sizes, driven by compressed air produced by a compressor. The sandblasting cabin and the compressor are located (in order to reduce the compressed air routes) in the room adjacent to that in which they are spray equipment. 3.2 Screw air compressor is ESM 7TK type and has the following technical and functional parameters:

• Lifting pressure …………………………………………..................... 7,5 bar; • Operating pressure ……………………………………………………. 7 bar; • Effective discharge ……………………………………………………. 1320 l/ min; • Tank capacity …………………………………………........................ 270 l; • Nominal Motor rating …………………………………………………. 7,5 kw; • Total absorbed power at operating pleasure ………………………. 9,58 kw; • Total absorbed power without charge ………………………………. 3,1 kw; • Voltage (frequency) …………………………………………. 400 VCA- triphased 50 Hz.

The screw air compressor is dotted with drying machine air system by refrigerating, with the following characteristics:

• Dew point ……………………………………………………… +3°C; • Voltage ………………………………………………………… 220VCA monophased-50 Hz;


62

• Consumed power …………………………………………….. 0,28 Kw; • Cooling agent …………………………………………………. R134A.

3.3 In the spraying cabin are placed the working piece manipulations and the robot on witch arm is mount the spaying gun. It has the following features.

• Working space ……………………………………..... L x l x h = 4300 x 3550 x 2500 mm; • Access through a door in 2 leafs…………………… L x l = 2500 x 2000 mm; • It is dotted with two windows with thermo glasses for watching the process and for interior

illuminating with two fluorescent lamps; • Walls of 100 mm thickness from galvanised sheet and sound absorbing material sandwich.

On the cabin ceiling it is mount an air recirculation system with the following characteristics: • Ventilation System………………………………………………BOX BV12/12 2,2 kw; • Flow ………………………… 5100 mc/ hour (with an initial pressure falling 45 daPa) • Electric supply…………………………………………………. 400VCA- triphased-50 Hz • Ventilation piping and dispersion from galvanised sheet, filter G Class

The sparying cabin is designed to protect personnel from the noise, nuisance and high temperatures that emit during the thermal spraying operation and is located inside the laboratory HVOF of ICTCM. Inside there are the handling devices and the robot that on its arm is fixed the sparying gun. The spraying cabin dimensions are LxWxH = 4300x3550x2500 mm. The cabin is fitted with an access door in two leaves, which are mounted sensors do not allow the operation of the spray and the robot when the door is open. Also, the cabin is equipped with two double glazed windows through which operators can track the process. 3.4 The handling device of parts with horizontal axis is used for parts with maximum diameter of 300 mm and maximum length of 1200 mm. They get at the head of a universal right and the left in a rotating top. The universal is driven to the right speed by a worm gear. 3.5 The handling device of parts with vertical axis is used for parts with maximum diameter of 500 mm and maximum length of 1000mm. It consists of a tilting rotary table driven by an electric motor mounted on a stand. 3.6 Fanuc Robot, model m-20I A

• Type…………………………………………………………….. articulated • Number of controlled axes …………………………………… 6; • Repeatability…………………………………………………… ±0,8 mm; • Working load …………………………………………………. 20 kg; • Working area …………………………………………………. 1811 mm; • Montage…………………………………………………………. Vertical, on the ground

Robot controller: • Command cabinet equipped with programming and command functions for the manipulator,

programming console; • Mobile console for programming for the operator; • Safety/blocking system for open door of the spraying cabin; • Collision detection module; • Electric supply ……………………………………….. 200-230 VCA +10% -15% 50 Hz; • Medium consumption power ……………………….. 1 kw.

The robot is necessary for handling system of a thermal spray equipment by HVOF process (High Velocity Oxygen Fuel). The robot operates in a cabin in which there take place the HVOF deposition process, and on the robot’s arm is fixed the sparying gun for metallization and supply hoses following specific process gas and liquid: oxygen, kerosene, metallizing powder mixed with nitrogen, cooling water . The robot’s task is to handle the the gun, as a program, for a wide the wide range of geometrical configurations and sizes there of: cylindrical, rectangular, etc. The robot is located and mounted so as to include in its work space handling devices with vertical axis and horizontal axis (rotary table) that are set pieces that will be covered by metallization. 3.7 Exhaust gases filtering system and evacuation pipes system

• Integrated ventilation system…………………………………………… ART 502 7,5 kw;


63

• Flow 5500 mc/hour at a pressure of …………………………………. 275 daPa; • Filtering cartridge THERMO-WEB/ limit temperature ………………. 1350°C, 12 pieces; • Total filtering surface…………………………………………………….. 168 mp; • Cleaning system with cartridges for compressed air.....pressure bar, flow rate 16,2 mc/hour; • Electric supply …………………………………………………… ……… 400VCA/50 hz; • Discharge of the contaminant elements:……………………………… 2 containers x 60 litres; • Piping from sheet metal zincked SPIRO helical fold for increasing rigidity: ……………Ø300

mm x 0,5 mm deeph; • Flexible pipes Ø300 mm x 0,085 mm deep of the wall formed by a steel wire covered with

inlayed bronze pasted with adhesive in multiple laminated layers, from aluminium sheet; • Normal running temperature ………………………………………….. -30/+140°C; • Maximum speed for the air ……………………………………………. 30 m/sec; • Maximum pressure …………………………………………………….. 2500 Pa.

The exhaust filtration system is necessary for the collection, disposal and filtration of flue, dust and fumes resulting from thermal spray technological process by HVOF (High Velocity Oxygen Fuel) with liquid fuel (kerosene). The evacuation are made by two horizontal and vertical handling devices that are included in the integrated technology system for thermal spraying by HVOF process. The two devices are equipped with suctions hood and they are located in a spray cabin where the process HVOF takes place. The emissions evacuation is achieved by a pipe that branching in two parts and on the one hand it make contact with the two suctions hood and on the other hand, after passing out of the spray cabin by HVOF laboratory at a distance of approx. 6800 mm and connected to the filter unit installed in the outside of the building laboratory. The dust from filtering is stored in two containers attached to the evacuation appliance. There is also an air reintroduction system into the spray cabin in order to rebalance the pressure form the inside, that is consisting of: fan, two filter with pockets - G4 class filter, duct airflow ventilation and dispersion. From a functional perspective, the exhaust filtration system consists of: emissions filter appliance; reinseration air system into cabin; exhaust pipe. 3.7 Technical gases and distribution networks. For the spray process is necessary 1200 liters / min at 20 bars of oxygen and 30 l / min at 6 bars of nitrogen. The oxygen is stored in two batteries each with 16 bottles of 50 liter and the storage pressure in cylinder is 200 barr. The nitrogen is stored in two cylinders, each having 50 liters at a pressure of 200 bars. The gas flow from the gas bottle to the gase locker of the spraying appliance through distribution networks.

Oxygen distributions pipes comprise the following elements: • Coil pipe, 2 metres……………………………………………………… 2 pieces; • Distribution ramp with one entering and 2 exits …………………….. 1 piece; • Reducer ………………………………………………………………… 1 piece; • Pneumatic valve; • Pipelines from cooper Distributions pipes for nitrogen it is composed by: • Serpentine, 2 meters ………………………………………………….. 1 piece; • Pressure regulator........ ………………………………………............ 1 piece; • Silicone flexible pipe

3.8 Security system of the holders and HVOF accesories. The batteries with oxygen cylinders, nitrogen cylinders and exhaust filtration plant are located outside the building next to where the spray plant are. Also, outside building, on the wall there are the elements of the distribution are networks, except for portions of the pipe and hose that enter into the control gase cabin of the spray plant. They are protected from access by unauthorized personnel, and also from the rays sunlight by closing into a security system. It has a roof of corrugated and galvanized sheets, side closures with access doors with frame made by pipe on that are welded nets. In addition to the wire guard is caught a protection netting that restrain the sunlight and also ensuring a good ventilation. The security system includes an uncovered locking for the air filter that is placed outside the building. This is equipped with doors that allow the cleaning of the filtering cartridges and access to the switchboard of the installation of filtering emissions.


64

3.9 Thermal spraying equipment GTV K2 torch for HVOF thermal spaying Combustion chamber Pressure box for the combustion chamber Water jacket

⎯ Fuel: …………………………………..…………….. Exxsol D 60 (kerosene) ⎯ Minimum caloric power……………………….………. 250 kW (10 kW per litre kerosene) ⎯ Minimum speed for the spraying jet: ……………………………… 2000 m/s ⎯ Maximum temperature of the spaying jet: ………………..……… 2800 ºC ⎯ Maximum quantity for the (WC-Co) sprayed powder: ……….…… 10 kg/h ⎯ Combustion temperature: ………………………………………….. 38 MJ/l ⎯ (λ) (oxygen quantity/ kerosene quantity) ratio for the maximum temperature:……....2,9

(λ) (oxygen quantity/ kerosene quantity) ratio for the neutral flame: ………………. 3,4 ⎯ Pressure in the combustion chamber: ……………………………………. max. 10 bar

GTV K2 torch assures forming of the incandescent jet which transports the melted powder at the deposit zone, the moving being assured by the robot on which arm it is mounted.

GTV Controler for gases (O2/ Air/ N2) ⎯ O2 Delivery:

Entering pressure: …………………………………… 20 bar Maximum flow: ……………………………………….. 1000 l/min

⎯ N2 Delivery: Entering pressure: …………………………..……….. 6 bar Maximum flow: ……………………………..…………. 30 l/min

⎯ Compressed air delivery: Entering pressure: …………………………..……….. 6 bar Minimum flow: ……………………………..………….. 1000 l/min

Assures the control and delivery of the gases and the compressed air to the torch where is formed the spraying jet which transports the powder for the HVOF spraying.

GTV Unit for kerosene pumping ⎯ Kerosene Delivery (Exxsol D 60)

Pressure: ……………………………………………… 25 bar Flow …………………………………………………… 30 l/min

Assures the control and distribution of the kerosene to the spraying torch where is formed the spraying jet which transports the powder for the HVOF spraying.

GTV PLC control unit with robot interface Consumption power: ……………………………..….. 2 kW Electric supply: ……………………………….. 400V C.A. – triphased – 50 Hz – 3A

Assure a biunique link with the Fanuc robot. GTV HVOF – Control console of operators (HMI)

Allows control and selection of process parameters including real-time monitoring of their. Feed system GTV / power measuring ⎯ Powder supply:

2 canisters x 1,5 l Powder mixer speed ………………….…………........ 0 – 100% Metering disc speed ……………………….……….... 0 – 10 rot/min Used power: ……………………………….…............. 2 kW Electrical supply ………………………….……........... 230 V – monophase – 50 Hz –

max 10 A GTV powder feeder type PF is a system that stores, supplies and distribute controlled with powder. The power supply consists essentially from a container of powder (unit dose) and a base, which incorporates the powder container, and also including the control and operation of Siemens S7. The powder container is a separate module and can therefore be put to different bases and is special designed according to customer requirements.


65

Standardized 1, 2, 3 or 4 powder canisters can be driven parallel (PF 2/1, PF 2/2, PF 3/3, PF 4/3 or PF 4/4). Furthermore to have the possibility, every powder canister with a weighing system to equip (PF 1/1W, PF 2/2W = scale). The device is a powder feeder for thermal spraying, laser welding or PTA hard facing. The device is used exclusively for the promotion of powdered materials. On the gas side the unit operates with argon/nitrogen or helium only. Oxygen and hydrogen and other flammable gases are not permitted under any circumstances!

Gun cooling system (heat exchanger) ⎯ Cooling water supply

Cooling capacity ……………………….……………....... 87,6 kW Ambient temperature ...……………………………......... +10 ... +420 C Maximum pressure ………………………….…………… 42 barr Refrigerant ………………………………………….......... R410A Used power ……………………………..….……............. 43,2 kW Power supply ……………………………………. 400V C.A. – triphase -50 Hz – 78A

4. Conclusions

In terms of materials that can be used for specific applications of the project, there are the following conclusions:

For industrial applications, materials have been indicated for the following applications: pomps for high pressue that are used in plant for water jet cutting; molds for glass; molds for plastic deformation of metals, hydraulic and pneumatic components - cylinders, pumps, valves, taps. Materials that can be used to cover by using HVOF process are the following two types:

a. Carbides such as WC-Co or WC-Co-Cr based on the type of application; b. Nickel alloys such as NiCrBSi; c. Oxides, such as Al2O3 can be used but HVOF process is less used for coating such material.

For medical applications were given materials for the following applications: surgical instruments; electrostatic coating for surgical parascopic. Mainly, materials that can be used to cover by using HVOF process are the following two types:

a. Carbides WC-Co or WC-Co-Cr for surgical instruments; b. Oxides, such as Al2O3 for isolating electrostatically - HVOF process is less used for coating

such material.

REFERENCES [1] Technical Documentation GTV Coating System HVOF-MF-K 1000, Project ICTCM, 662.013 [2] "Study regarding the theoretical determination of specific technological parameters for HVOF process on application"

project no. 614 SMIS code / CNRS: 12537, contract no .: 270 / 27.10.2010, project "Applied researches, technology and technological equipment for high strength thermal spraying by HVOF process used in industrial and medical applications", co-funded by the Regional Development European Fund, under the contract financing 270 / 27.10.2010, in the Operational Programme "Increasing Economic Competitiveness" (SOP IEC), Priority Axis 2 Research, Technological Development and Innovation, Operation 2.1.2- „High scientific level R&D Projects attended by specialists from abroad" .

[3] “Research on identifying applications and parameters specific to HVOF process - Study on the determination of spray materials used in each case”, project no. 614 SMIS code / CNRS: 12537, contract no.: 270 / 27.10.2010, project "Applied researches, technology and technological equipment for high strength thermal spraying by HVOF process used in industrial and medical applications", co-funded by the Regional Development European Fund, under the contract financing 270 / 27.10.2010, in the Operational Programme "Increasing Economic Competitiveness" (SOP IEC), Priority Axis 2 Research, Technological Development and Innovation, Operation 2.1.2 - „High scientific level R&D Projects attended by specialists from abroad".

[4]. Arash Ghabchi, Tommi Varis, Erja Turunen, Tomi Suhonen, Xuwen Liu, S.-P. Hannula„Behavior of HVOF WC-10Co4Cr Coatings with Different Carbide Size in Fine and Coarse Particle Abrasion”, Journal of Thermal Spray Technology, January 2010

[5]. Brandl W., G. Marginean, D. Utu, D. Maghet, “High Performance Coatings for Protection of Components Against High Temperature Corrosion”, Advanced Materials, pp. 57-64, Timisoara, Romania, 2004;

[6]. Brandl W , Utu D., Marginean G., Cartis I., Serban V.A., “Morphology and Phase Modification of HVOF-Sprayed McrAlY-Coatings Remelted by electron Beam Irradiation”, Vacuum 77/4, pp. 451-455, 2004


66

THE PROCEDURE FOR DRYING PLANT PRODUCTS IN CONVECTIVE DRYERS

PhD.s. Eng. Iulian – Cezar GIRLEANU, PhD. Eng. Gabriela MATACHE INOE 2000-IHP, [email protected]

Abstract: This paper shows the advantages of using convective dryers and their performance in terms of energy. These are meant for dehydration of vegetal products, in line with the global trend concerning conservation through the thermohydric technology of enzyme inactivation (dehydration). In the paper two concepts are promoted which are strictly up-to-date in the present context of deepening of energy and food crisis at global level: the concept of energy independence and the concept of food security and safety for consumers.

Keywords: convective dryers, plant products, dehydration, energy independence, food security and safety

1. Introduction

Convective drying remains, also nowadays, the best known and widespread process of removing moisture from the material, both due to the simplicity of the process, and especially due to the numerous opportunities to obtain, at low cost, high quality of drying in a short period of time. Drying is a complex operation involving transient heat and mass transfer along with various processes, such as physical and chemical changes which, in turn, can cause changes in the quality of the product just like the mass and heat transfer mechanisms. Physical changes that may occur are: contracting, swelling, crystallization, glass transformation. In some cases, there may be chemical or biochemical reactions desirable or not which can affect the color, texture, smell, or other properties of the solid product. In intensive drying processes it is intended to accomplish a uniform contact between the thermal agent and the biomaterial granules which is done in relatively homogeneous layer structures. This challenge is imposed by the fact that in the heat treatment of biomaterials there could occur significant degradation of the quality of the final product. Drying is one of the traditional ways and yet always modern for storing on extended periods of time vegetables and fruits for direct consumption or for industrial processing without addition of preservatives and low power consumption for storage and reprocessing. Convective drying is an intensive thermal energy technology, which in many cases makes it dependent on the heat sources which are as cheap as possible, one reason for super concentration of drying plants. Rapid price decline in automation devices, the development of the automated management software and also the development of machine building technology have led to a decentralization of processing fruits and vegetables by drying, to the displacement of drying facilities at the place of harvest of the products to be dried. This makes the use of mobile dryers dependent on the use of diesel oil and LPG, which are fuels with high energy density, but sources of pollution through the emission of CO2. Vegetables and fruits throughout the history of humanity were the basic elements of food, due to their content in proteins, fat and carbohydrates, minerals such as potassium, sodium or magnesium etc., their use throughout the year being good for health. Pedoclimatic and relief conditions in Romania have made it possible that on this territory to be grown a variety of vegetables and fruit, of great importance, divided into more than 15 botanical families. However, these products are seasonal, have relatively short harvesting periods, and the perishable nature of


67

most of them is very high or medium, making their use as fresh products be possible only as a result of exquisite storage, which significantly increases costs.

2. The main advantages of vegetables and fruit preserved by drying

Drying of fruit and vegetables is the healthiest solution for long time preservation. Another advantage of the dehydrated fruits and vegetables is that they have a validity term greater than frozen or canned ones. Actually, dried and stored in optimal conditions, fruits and vegetables can be eaten even after several years. An important economic aspect of dehydrated vegetables and fruits is that their storage does not pose serious problems because their volume is reduced significantly after the drying process. For example, two kilograms of raw fruit after drying will be a quarter of the initial volume. There can be dehydrated almost all fruits and vegetables, with the exception of the vegetal fat-rich ones because they can become greasy. Grapes, plums, apples, pears, peaches, apricots, pineapple, bananas, tomatoes, carrots and herbs are best suited for this operation. Dehydration can be done by simply placing the fruits and vegetables in the sun, as it was done hundreds of years ago; however the dehydration plant is the best solution, because the drying process in the drying facility will shorten significantly the time of dehydration of fruits and vegetables. In Moldavia, a grid called “lojniţă” is used for dehydrating apples, pears and plums, often resorting also to cold smoke. In this case, the process is called smoking (plums, apples and pears are preferred). There are used varieties that are not very sweet, because there is a risk after dehydration for resulting juice to leak.

3. The drying of vegetal products in convective dryers using warm currents and facilities for this type of drying

Convective drying remains, also nowadays, the best known and widespread process of removing moisture from the material, both due to the simplicity of the process, and especially due to the numerous opportunities to obtain, at low cost, high quality of drying in a short period of time. The wet material gets into contact with the drying agent - hot air or combustion gases – receiving from it, by convection, 80-90% of the total quantity of heat necessary for the drying process. The parameters (speed, temperature, relative humidity, etc.) of the drying agent, as well as the connection between humidity and material determine the heat and mass transfer in the drying process. In the process, the drying agent changes its temperature, relative humidity and even circulation speed, and the wet material changes its density, specific heat, thermal conductivity and even dimensions. The drying process is a complex process during which many parameters (coefficients of heat and mass transfer, the viscosity of the water, surface tension, etc.) change, so that for exact knowledge of the development of the process there is necessary a correlation between the known theoretical results and the direct experimental research carried out for each material.

Experimentally, the peculiarities of the drying process of wet material are given by the drying curves (which show the change in humidity over time), the drying speed curves (which show the variation of drying rate with moisture or over time), the variation of material temperature and drying agent over time etc.

From the point of view of heat transmission in order to eliminate moisture the drying can be: - Convective drying - heat transfer by convection from air or other gases to the material subjected to drying; - Conductive drying - heat transfer by conduction, by means of a heat transfer surface; - Dielectric drying - dielectric heating of the material in a HFC (high frequency currents) field; - Radiant drying - heat transfer by radiation.


68

4. The general functional diagram of a convective dryer The component parts of a dryer type chamber with trolleys and shelves are: 1- the dryer chamber; 2- trolleys (carriages) with racks or shelves; 3- fan; 4- external radiator for heating the mixture of air; 5,6- internal radiators for intermediate heating of drying agent; 7- choke for the adjustment of exhaust air recirculation. Its operation is an elementary one; ambient air is introduced into the drying plant after initially was passed through a heat exchanger. This one is meant to provide the introduced fresh air with the temperature necessary to the drying process for that phase. The air is then passed on in the installation to a system of choke valves, which is intended to control the flow of thermal agent introduced into the drying chamber, thus being achieved in a simple manner the dosing of hot air; this one, taken by a fan, is sent through a pipe system to the drying chamber where there are previously placed the vegetal products that are to be subjected to the drying process.

Fig. 1 The general functional diagram of a convective dryer type chamber with trolleys and shelves.

After going through the entire chamber, the air is already moist, because it has taken over part of the moisture of vegetable products, following that part from that one to be discharged, and the other part be recirculated, thus reducing the amount of fuel used for heating the air. This diagram focuses on energy saving and promotion of work processes as profitable as possible in terms of energy, important features in the field of convective dryers.


69

5. Types of drying Batch drying:

Fig. 2 Diagram of a convective dryer with circulation through layer panels

Fig. 3 Diagram of a convective dryer with tangential circulation panels


70

The advantages of this type of drying are: - material to be dried is spread evenly across panels that are stacked on trolleys or slideways; - hot air is introduced with an automatically controlled temperature, constant, or greater at the

beginning and lower at the end of drying; - temperature and humidity at the output are measured and there is calculated the average

temperature at the material surface; - there is adjusted the ratio external air/thermal agent recirculated in order to control the surface

temperature of the material to be dried; - if constructively possible, there is changed periodically the direction of travel of drying agent in

order to obtain even drying.

Semi-continuous drying: - material to be dried is spread evenly across panels that are stacked on trolleys which are

inserted and pulled out periodically; - hot air is introduced with an automatically controlled temperature; - temperature and humidity of drying agent at the output are measured and there is calculated

the average temperature at the material surface; - there is adjusted the ratio external air/thermal agent recirculated in order to control the surface

temperature of the material to be dried; - circulation of the drying agent and the trolleys is done: in co-current, counter-current or mixed

flow.

Fig. 4. Fruit and vegetable dryer tunnel type - functional diagram

6. Conclusions

One of the easiest ways to keep the quality of fruits and vegetables is their preservation by drying or dehydration. While drying is performed based on natural heat transfer of water from vegetal


71

products to the outside, dehydration assumes that the same transfer is performed under strict human control, by using adequate technical equipment. Industrial scale dehydration of food products, characterized by relatively high production costs, is widely used as the final products have low weight and volume and, through strict control of technological operations, there is ensured compliance with the current regulations on hygiene and food safety. Convective drying is the most common method of removing moisture from fruit and vegetables, both due to the simplicity of the process, and especially due to the numerous opportunities to obtain, at low cost, high quality of drying in a short period of time.

REFERENCES

[1] Arun S. Mujumdar and Sakamon Devahastin: "Principii fundamentale ale uscarii"/"Fundamentals of drying";

[2] Erol Murad, Aurelian Crăciunescu, Georgeta Haraga, Uscatoare mobile pentru zona montana cu impact ecologic redus/ Mobile dryers for mountain areas with low environmental impact, Politehnica University of Bucharest;

[3] Erol Murad, David Ladislau, Victor Safta, Gabriela Balacianu "Uscarea convectiva a produselor agricole-forma moderna si economica de pastrare si valorificare"/"Convective drying of agricultural products - modern and economical way for storage and valorification", Politehnica University of Bucharest 2006

[4] Andreea Lavinia R.I. MARIN, “Cercetari privind optimizarea energetică a procesului de conservare prin uscare a fructelor si legumelor”/ “Research on optimizing energy in the conservation process by drying fruits and vegetables”, Brasov 2012;

[5] Rasenescu L.: "Operatii si utilaje in Industria Alimentara"/ "Operations and equipment in food industry", Vol II, Technical Publishing House, Bucharest, 1972;

[6] Ţane, N., Gaceu, L.: "Maşini, instalaţii şi utilaje pentru produse de origine vegetală"/"Machines, installations and tools for plant products", Publisher University "Transilvania" of Brasov, 2000;

*** http://www.agenda.ro/o-metoda-naturala-de-conservare/--"Deshidratarea fuctelor si legumelor"/ "Dehydration of fruits and vegetables", September 16, 2009

http://www.agenda.ro/o-metoda-naturala-de-conservare/

http://hidraulica.fluidas.ro