Thermal engineering om

basics of thermodynamics, laws of thermodynamics, power plants

1. THERMAL ENGINEERING
A.THERMODYNAMICES
PROF . SHEKHAR S. BABAR
MECHANICAL ENGINEERING DEPARTMENT
ICEM

2. THERMODYNAMICES
THERMO---Heat Released
DYNAMICS -----Mechanical Action For doing work
The study of the effects of work, heat flow, and energy on a
system
Movement of thermal energy
Engineers use thermodynamics in systems ranging from
nuclear power plants to electrical components.
Thermodynamics is the study of the effects of
work, heat, and energy on a system
Thermodynamics is only concerned with macroscopic (large-
scale) changes and observations

3. SYSTEM, SURROUNDING ,UNIVERSE
SYSTEM-Areaunderthermodynamicstudy
SURROUNDING–Areaoutsidethesystem
BOUNDARY-System&Surroundingare
separatedbysomeImaginaryOrreal
Surface/Layer/Partition
UNIVERSE–System&Surroundingsput
togetheriscalledUniverse

4. 4
ISOLATED, CLOSED AND OPEN
SYSTEMS
Isolated
System
Neither energy nor
mass can be
exchanged.
E.g. Thermo flask
Closed
System
Energy, but not mass
can be exchanged.
E.g. Cylinder filled with
gas & piston
Open
System
Both energy and mass
can be exchanged.
E.g. Gas turbine, I.C.
Engine

5. THERMODYNAMIC PROPERTIES
ThermodynamicProperties–Itismeasurable&
Observablecharacteristicsofthesystem.
Extensive:Dependonmass/sizeofsystem
(Volume[V]),Energy
Intensive:Independentofsystemmass/size
(Pressure[P],Temperature[T])
Specific:Extensive/mass(SpecificVolume[v])

6. PRESSURE
P = Force/Area
Pa, Kpa,Bar, N/m
2
Types:
Absolute
Gage (Vacuum)
Atmospheric
P
abs =P
atm+/-P
gauge
PRESSURE PRESSURE

7. Volume
Three dimensional
space occupied by an
object
Unit-M
3
, Liter
1 m
3
= 10
3
lit
Volume Volume

8. Temperature
Quantitative
indicationofDegree
ofHotness&coldness
ofthebody.
Unit-
0
C,K,F
Thermometer
Thermometry
Temperature Temperature Scale

9. Internal energy
Internalenergy(alsocalledthermal
energy)istheenergyanobjector
substanceisduetothekineticand
potentialenergiesassociatedwith
therandommotionsofallthe
particlesthatmakeitup.
Internalenergyisdefinedasthe
energyassociatedwiththe
random,disorderedmotionof
molecules.
Unit-KJ , Joule
Internal Energy Internal Energy [U]

10. Enthalpy
Total Heat content of
Body
Heat supplied to the
body Enthalpy increases
& decreases when heat
is removed
Enthalpyis a
measure of the total
energyof a
thermodynamic
system.
Enthalpy Enthalpy

11. Work
Work=ForcexDisplacement(Nm)(Joule)
EnergyinTransient
Pathfunction
Highgradeenergy
Workdonebythesystemonthesurrounding
-Positivework
Workdoneonthesystembysurrounding–
Negativework

12. HEAT
Energy transfer by virtue of temperature
difference
Transient form of energy
Path function
Low grade energy
Negative heat-heat transferred from the system
( heat rejection)
Positive heat –heat transferred from surrounding
to system (heat absorption)

13. HEAT
Energy transfer by virtue of
temperature difference
Transient form of energy
Path function
Low grade energy
Negative heat-heat
transferred from the system
( heat rejection)
Positive heat –heat
transferred from
surrounding to system
(heat absorption)
HEAT CONCEPT
hot cold
heat
26°C 26°C

14. Work & Heat
Workistheenergy
transferredbetweena
systemandenvironment
whenanetforceactson
thesystemoveradistance.
Thesignofthework
Workispositivewhenthe
forceisinthedirectionof
motion
Workisnegativewhenthe
forceisoppositetothe
motion
WORK WORK

15. LAWS OF THERMODYNAMICS
FIRST LAW OF THERMODYNAMICS
(LAW OF ENERGY CONSERVATION)
SECOND LAW OF THERMODYNAMICS
ZEROTH LAW OF THERMODYNAMICS

16. Zerothlaw of thermodynamics

17. FIRST LAW OF
THERMODYNAMICS
CONSERVATIONOFENERGY
ALGEBRAICSUMOFWORKDELIVEREDBYSYSTEM
DIRECTLYPROPOTOPNALTOALGEBRAICSUMOF
HEATTAKENFROMSURROUNDING
HEAT&WORKAREMUTUALLYCONVERTIBLE
NOMACHINECAPABLEOFPRODUCINGWORK
WITHOUTEXPENDITUREOFENERGY
TOTALENERGYOFUNIVERSEISCONSTANT

18. LIMITATIONS OF FIRST LAW OF THERMODYNAMICS
Can’t give the direction of proceed can
proceed-transfer of heat from hot body to
cold body
All processes involved conversion of heat
into work & vice versa not equivalent.
Amount heat converted into work & vice
versa
Insufficient condition for process to occurs

19. HEAT RESERVOIR, HEAT SOURCE, HEAT SINK
HEATRESERVOIR-Sourceofinfiniteheatenergy&
finiteamountofheataddition&heatrejectionfrom
itwillnotchangeitstemperature
E.g.Ocean,River,LargebodiesofwaterLake
HEATSOURCE-Heatreservoirswhichsuppliesheat
tosystemiscalledheatsource
HEATSINK-Heatreservoirwhichreceivesabsorbs
heatfromthesystem

20. 2
ND
LAW OF THERMODYNAMICS
KELVIN –PLANCK’S STATEMENT
Itisimpossibleto
constructamachine
whichoperatesincycle
whosesoleeffectisto
convertheatinto
equivalentamountof
work

21. 2
ND
LAW OF THERMODYNAMICS
CLAUSIUS STATEMENT
Itisimpossibleto
constructamachine
whichoperatesin
cyclewhosesole
effectistotransfer
heatfromLTBtoHTB
withoutconsuming
externalwork
CONCEPT STATEMENT

22. 22
2
nd
Law: Clausius and Kelvin
Statements
Clausius statement (1850)
Heat cannot by itself pass from a colder
to a hotter body; i.e. it is impossible to
build a “perfect” refrigerator.
The hot bath gains entropy, the cold bath loses it.
ΔS
univ= Q
2/T
2–Q
1/T
1= Q/T
2–Q/T
1<
0.
Kelvin statement (1851)
No process can completely convert heat
into work; i.e. it is impossible to build a
“perfect” heat engine.
ΔS
univ= –Q/T <0.
1
st
Law:one cannot get something for nothing (energy
conservation).
2
nd
Law: one cannot even break-even (efficiency must be less
than unity).
Q
1= Q
2 = Q
M is not active.

23. HEAT ENGINE
Thermodynamic
system/Device
whichoperatein
cycleconvertsthe
heatintouseful
work.
HEAT ENGINE
HEAT ENGINE

24. HEAT ENGINE
Efficiency = e = W/Qshot
cold
hot
coldhot
hot
Q
Q
Q
QQ
Q
W
e 1 !!Kelvins!in measured be
must res temperatuThe :Note
1
hot
cold
Carnot
T
T
e

25. HEAT PUMP
Thermodynamicsystem/Devicewhich
operateincycleconvertstheheatinto
usefulwork.
Cold Reservoir, T
C
P
Hot Reservoir, T
H
Q
H
Q
C
WORK

26. HEAT PUMP & REFRIGERATOR
HEATPUMP
Cold Reservoir, T
C
R
Hot Reservoir, T
H
Q
H
Q
C
W
Cold Reservoir, T
C
P
Hot Reservoir, T
H
Q
H
Q
C
W

27. 27
Reversible Engine: the Carnot Cycle
Stage 1Isothermal expansion at
temperature T
2, while the entropy
rises from S
1to S
2.
The heat enteringthe system is
Q
2= T
2(S
2–S
1).
Stage 2adiabatic (isentropic)
expansion at entropy S
2, while the
temperature drops from T
2to T
1.
Stage 3Isothermal compression at
temperature T
1, while the entropy
drops from S
2to S
1.
The heat leaving the system is
Q
1= T
1(S
2–S
1).
Stage 4adiabatic (isentropic)
compression at entropy S
1, while the
temperature rises from T
1to T2.
Since Q
1/Q
2= T
1/T
2,
η= η
r= 1 –T
1/T
2.

28. POWER PLANT ENGINEERING
PROF. S. S. BABAR (MECHANICAL ENGG. DEPT)

29. POWER PLANT
HYDROELECTRIC POWER PLANT
THERML POWER PLANT
NUCLEAR POWER PLANT
SOLAR POWER PLANT
WIND POWER PLANT
GEOTHERMAL POWER PLANT
TIDAL POWER PLANT

30. THERMAL POWER PLANT
COMPONENTS
1. STEAM GENERATOR
2. STEAM TURBINE
3. GENERATOR
4. CONDENSER
5. FEED PUMP

31. THERMAL POWER PLANT
Cheaper fuels used
Less space required
Plant near the load
centers so less
transmission cost
Initial investment is
less than other plants
Plant set up time is
more
Large amount of water
required
Pollution
Coal & ash handling
serious problem
High maintenance cost
ADVANTAGES DISADVANTAGES

32. HYDROELECTRIC POWER PLANT

33. HYDROELECTRIC POWER PLANT
RESERVOIR
DAM
TRASH RACK
GATE
PENSTOCK
TURBINE
GENERATOR
TAIL RACE
COMPONENTS HYDRO-ELECTRIC PLANT

34. HYDROELECTRIC POWER PLANT

35. HYDROELECTRIC POWER PLANT
No fuel required
No pollution
Running cost low
Reliable power plant
Simple design &
operation
Water source easily
available
Power depends on
qty of water
Located away from
load center-
transmission cost
high
Setup time is more
Initial cost -high
ADVANTAGES DIS ADVANTAGES

36. NUCLEAR POWER PLANT

37. NUCLEAR POWER PLANT

38. NUCLEAR POWER PLANT

39. WPUI –Advances in Nuclear 2008
Fission controlled in a Nuclear Reactor
Steam
Generator
(Heat
Exchanger)
Pump
STEAM
Water
Fuel Rods
Control Rods
Coolant and Moderator
Pressure Vessel and Shield
Connect
to
Rankine
Cycle

40. Large amount of
energy with lesser
fuels
Less space
No pollution
Cost of power
generation is less
Setup cost –more
Availability of fuel
Disposal of radioactive
waste
Skilled man power
required
Cost of nuclear reactor
high
High degree of safety
required
ADVANTAGES DIS ADVANTAGES
NUCLEAR POWER PLANT

41. WIND POWER PLANT

42. WIND POWER PLANT
AIR IN MOTION CALLED WIND
KINETIC ENERGY OF WIND IS CONVERTED
INTO MECHANICAL ENERGY
K.E. = (M X V
2
)/2
ROTOR
GEAR BOX
GENERATOR
BATTERY
SUPPORT STRUCTURE

43. WIND POWER PLANT

44. WIND POWER PLANT
No pollution
Wind free of cost
Can be installed any
where
Less maintenance
No skilled operator
required
Low energy density
Variable, unsteady, in
termittent supply
Location must be
away from city
High initial cost
ADVANTAGES DIS ADVANTAGES

45. SOLAR POWER PLANT

46. Freely & easily
available
No fuel required
No pollution
Less maintenance
No skilled man
power req.
Dilute source
Large collectors
required
Depends on
weather conditions
Not available at
night
ADVANTAGES DIS ADVANTAGES
SOLAR POWER PLANT

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