se20 – heating systems
DESCRIPTION
SE20 – Heating systems. Doc.Ing.Karel Kabele,CSc. Room: A122 kabele @fsv.cvut.cz. Lecture 1 Introduction. Lectures schedule. 1 The built environment. Applied thermo mechanics. 2 MULCOM 3 Heat loss and consumption calculations. Principles of heating equipment. - PowerPoint PPT PresentationTRANSCRIPT
Czech Technical University in Prague Faculty of Civil Engineering
Department of Microenvironmental and Building Services Engineering
Czech Technical University in Prague Faculty of Civil Engineering
Department of Microenvironmental and Building Services Engineering
SE20 – Heating systemsSE20 – Heating systemsSE20 – Heating systemsSE20 – Heating systemsLecture 1Lecture 1
IntroductionIntroduction
Lecture 1Lecture 1
IntroductionIntroduction
Doc.Ing.Karel Kabele,CSc.Doc.Ing.Karel Kabele,CSc.
Room: Room: A122A122
[email protected]@fsv.cvut.cz
Lectures scheduleLectures schedule
11 The built environment. Applied thermo mechanics.The built environment. Applied thermo mechanics.22 MULCOMMULCOM33 Heat loss and consumption calculations. Principles of heating Heat loss and consumption calculations. Principles of heating
equipment. equipment. 44 Heat emittersHeat emitters, space heating, space heating55 (Easter Monday)(Easter Monday)66 Heating systemsHeating systems 77 Heating systemsHeating systems88 Boilers, boiler plantsBoilers, boiler plants99 Heat exchangers, district heatingHeat exchangers, district heating1010 Renewable sources, combined heat and power plantsRenewable sources, combined heat and power plants1111 Safety device for central heating systemsSafety device for central heating systems1212 Pumps in heating systemsPumps in heating systems13 13 Hot water generationHot water generation1414 Heating system control, building energy management systemsHeating system control, building energy management systems
History 700 B.C. - 0History 700 B.C. - 0
HypocaustaHypocaustaGreece, Italy, Greece, Italy,
TurkeyTurkey
Historie – medieval ageHistorie – medieval age
Stoves, fireplacesStoves, fireplaces
History 18-19.century History 18-19.century steamsteam
History 20.centuryHistory 20.centuryhot-water systemshot-water systems
Electricity,Water systemsCast-iron boilersCoal, Gas
Boiler Strebl 1927
Present and future?Present and future? Warm water Warm water
systemssystems Gas boilers Gas boilers
controled by controled by microprecessormicroprecessor
Heat emmitters Heat emmitters located in the floor, located in the floor, walls and ceilingwalls and ceiling
Computer modelling Computer modelling and simulationand simulation
Applied thermodynamicsApplied thermodynamics
Heat, heat energyHeat, heat energy Heat is the energy transferred between a Heat is the energy transferred between a
system and its surroundings due solely to a system and its surroundings due solely to a temperature difference between the system temperature difference between the system and some parts of its surroundings.and some parts of its surroundings.
TemperatureTemperature State variable describing kinetics energy of State variable describing kinetics energy of
the particles of the systemthe particles of the system Thermodynamic Thermodynamic /Kelvin/ /Kelvin/ T T [[KK]] Celsius t Celsius t [[°C°C]] t= T-273,15 t= T-273,15 Fahrenheit Fahrenheit [[°F°F]] 1°F=5/9°C 1°F=5/9°C (°F-32).5/9=°C(°F-32).5/9=°C
Basic laws of Basic laws of thermodynamicsthermodynamics
Zeroth law Zeroth law There is a state variable There is a state variable TEMPERATURETEMPERATURE. Two . Two
systems at the same temperature are in systems at the same temperature are in thermodynamics equilibrium. thermodynamics equilibrium.
The zeroth law of thermodynamics states that The zeroth law of thermodynamics states that if for example you have a Body (A) and a Body if for example you have a Body (A) and a Body (B), both at the same temperature; and then (B), both at the same temperature; and then you have a Body (C) which is at the same you have a Body (C) which is at the same temperature as Body (B); Therefore the temperature as Body (B); Therefore the temperature of Body (C) is equal to the temperature of Body (C) is equal to the temperature of Body (A). temperature of Body (A).
Basic laws of Basic laws of thermodynamicsthermodynamics
1.law1.law The total energy of the system plus the The total energy of the system plus the
surroundings is constant.surroundings is constant. 2.law2.law
The second law is concerned with The second law is concerned with entropy (S)entropy (S), , which is a which is a measure of disordermeasure of disorder. . The The entropy of the universe increasesentropy of the universe increases..
3.law3.law It is impossible to cool a body to absolute zero It is impossible to cool a body to absolute zero
by any finite processby any finite process
Heat transfer modesHeat transfer modes Heat ConductionHeat Conduction
Heat is transferred between two Heat is transferred between two systems through a connecting medium, systems through a connecting medium, Biot-FourierBiot-Fourier
Heat Convection Heat Convection Macroscopic movement of the matter in Macroscopic movement of the matter in
the forms of convection currents. the forms of convection currents. Newton-Richman, Fourier-KirchhofNewton-Richman, Fourier-Kirchhof
Heat transferHeat transfer
TransmissionTransmission convection+conduction+convectionconvection+conduction+convection
Radiation Radiation Electromagnetic wavesElectromagnetic waves
Indoor environmentIndoor environment Theory of the indoor environmentTheory of the indoor environment
Hygrothermal microclimateHygrothermal microclimate Acoustic Acoustic microclimatemicroclimate Psychical Psychical microclimatemicroclimate Light Light microclimatemicroclimate Electrostatic Electrostatic microclimatemicroclimate
Hygrothermal microclimateHygrothermal microclimate Indoor environment state from the viewpint of Indoor environment state from the viewpint of
thermal and moisture folws between the thermal and moisture folws between the human body and surroundingshuman body and surroundings
Heat Exchange between the Heat Exchange between the Human Body and the EnviromentHuman Body and the Enviroment
Metabolic Rate MMetabolic Rate M degree of muscular activities,degree of muscular activities, environmental conditions environmental conditions body size.body size.
Heat loss QHeat loss Q RespirationRespiration ConvectionConvection RadiationRadiation ConductionConduction EvaporationEvaporation
Body thermal balance equationBody thermal balance equationM=Q comfortM=Q comfortMM>Q >Q hothotMM<Q <Q coldcold
T
a
T
p
Factors Influencing Thermal Factors Influencing Thermal ComfortComfort
HumanHuman Metabolic RateMetabolic Rate Clothing InsulationClothing Insulation
SpaceSpace Air Temperature (Dry-Bulb)Air Temperature (Dry-Bulb) Relative HumidityRelative Humidity Air VelocityAir Velocity Radiation (Mean Radiant Temperature)Radiation (Mean Radiant Temperature)
Environmental indicesEnvironmental indices
Operative TemperatureOperative Temperature
where where ttgg = operative temperature = operative temperature ttaa = ambient air temperature = ambient air temperature ttrr = mean radiant temperature = mean radiant temperature hhcc = convective heat transfer coefficient = convective heat transfer coefficient hhrr = mean radiative heat transfer = mean radiative heat transfer coefficientcoefficient
rc
rrc
hh
thth a
gt
Environmental indicesEnvironmental indices Mean Radiant TemperatureMean Radiant Temperature
where where tr = mean radiant temperaturetr = mean radiant temperature Ti = temperature of the surrounding Ti = temperature of the surrounding
surface i, surface i, i=1,2,....,ni=1,2,....,n φφrnrn = shape factor which indicates the = shape factor which indicates the
fraction of total radiant energy leaving fraction of total radiant energy leaving the clothing surface 0 and arriving the clothing surface 0 and arriving directly on surface i, i=1,2,...ndirectly on surface i, i=1,2,...n
273.T....Tt 4 4nrn
41rr1r
MeasurinMeasuring g
instrumeinstrumentsnts
Thermal comfort Thermal comfort evaluationevaluation
PMV index PMV index (Predicted mean (Predicted mean vote)vote)
PPD index PPD index (Predicted (Predicted percentage of percentage of dissatisfied)dissatisfied)