This course covers fundamentals of thermodynamics and its applications. The objectives are to understand various energy concepts and laws of thermodynamics. Key topics include the first law relating heat and work, the second law and concept of entropy, properties of pure substances and steam, and analysis of common thermodynamic cycles. Assessment is based on assignments, tests, and a final exam covering all topics with emphasis on later modules. The course content is divided into six units covering topics such as the second law of thermodynamics, properties of steam, gas power cycles, vapor power cycles, air compressors, and gas turbines.

2. COURSE OBJECTIVES:
1. Understand various types of energies and its applications in thermodynamic systems
2. Applying thermodynamic concepts to thermodynamic systems
3. Know various laws of thermodynamics and applications to thermodynamic system
4. Application of ideal gas processes to thermodynamic systems
5. Study steam properties, Interpret steam tables and Mollier charts with numerical applications
6. Understand and analyze (numerical analysis) various types of air standard cycles

3. ISE 1 and ISE 2 are based on assignment/declared test/quiz/seminar/Group Discussions etc.
MSE: Assessment is based on 50% of course content (Normally first three modules)
ESE: Assessment is based on 100% course content with60-70% weightage for course content
(normally last three modules) covered after MSE.
Assessment Marks
ISE 1 10
MSE 30
ISE 2 10
ESE 50
ASSESSMENT SCHEME

4. COURSE CONTENT
Unit
No.
Content Lectures
Hrs.
1 Numerical treatment on second law, Clausius theorem, Entropy, Clausius inequality, Entropy as a
property of system, Entropy of pure substance. T-s and h-s planes, Entropy change in a reversible and
irreversible processes, Increase of entropy principle, Calculation of entropy changes of gases and
vapors,(numerical treatment should be based on processes) Availability: Available and unavailable
energy: availability of a closed and open system, Availability of work and heat reservoirs, Anergy and
Exergy.
8
2 Properties of Pure Substances :
Pure substance, Phase change processes, Property diagram for phase change process (T-v, p-T, p-V
diagram, p-v-T surface), Triple point of water, Properties of steam, Deviation of real gases from Ideal
gases, Equations of state: Vander Waal, Beattie-Bridgeman, Virial and Diterici's equations.(Descriptive
treatment)
6
3 Gas Power Cycles:
Air Standard cycles: Assumptions, the Carnot Cycle, Otto Cycle, Diesel Cycle and Dual Combustion
Cycle. Comparison of Otto, Diesel and Dual Combustion Cycles. Expression for air standard efficiency
and mean effective pressure for Otto, Diesel and Dual Combustion cycle.
8

5. COURSE CONTENT
Unit
No.
Content Lectures
Hrs.
4 Vapour Power Cycles:
Carnot cycle using steam, Limitations of Carnot cycle Rankine cycle, Representation on T-s and h-s
planes, Thermal efficiency, Specific steam consumption. Work ratio, Effect of steam supply pressure
and temperature, Effect of condenser pressure on the performance. (Numerical Treatment), Reheat and
regenerative steam power cycles. Use of steam table and Mollier chart.
6
5 Reciprocating Air Compressors:
Application of compressed air, classification of compressor, Reciprocating compressors, construction ,
Work input, Necessity of cooling , Isothermal efficiency, Heat rejected, Effect of clearance volume,
Volumetric efficiency, Necessity of multistaging, construction, Optimum intermediate pressure for
minimum work required, After cooler, Free air delivered, air flow measurement, Capacity control.
6
6 Gas turbines:
Working principles, Applications, Gas Turbine Cycle-Brayton Cycle Ideal Brayton cycle. Calculation
of gas turbine work ratio, Efficiency etc. Pressure ratio for maximum work.. Open cycle gas turbine-
actual Brayton cycle. Methods for improvement of thermal efficiency of open cycle gas turbine plant.
Effect of operating variables on thermal efficiency . Closed cycle gas turbine.
6

6. REFERENCES
1. Thermodynamics: An Engineering Approach, 3rd Edition, Yunus A Çengel and Michael,
Boles, Tata McGraw Hill.
2. Basic and Applied Thermodynamics, 2nd Edition, Nag P. K., Tata McGraw-Hill.
3. Sonntag, R. E., Borgnakke, C., & Wylen, G. J. V. Fundamentals of thermodynamics:
Wiley.
4. Moran, M. J., Shapiro, H. N., Boettner, D. D., & Bailey, M. Fundamentals of Engineering
5. Jones, J. B., & Dugan, R. E. Engineering thermodynamics: Prentice Hall.
6. Potter, M. C., & Somerton, C. W. Schaum's Outline of Thermodynamics for Engineers,
McGraw-Hill.
7. NPTEL course “Basic Thermodynamics”,
URL:https://nptel.ac.in/courses/112/105/112105123/

7. UNIT 1
BASICS OF THERMODYNAMICS
SY Mechanical
Presented by
Prof. Bore S. B.
2020-2021

8. CONTENT
● Numerical treatment on second law,
● Clausius theorem, Clausius inequality
● Entropy,
● Entropy as a property of system, Entropy of
pure substance.
● T-s and h-s planes,
● Entropy change in a reversible and
irreversible processes,
● Increase of entropy principle,
● Calculation of entropy changes of gases
and vapors,(numerical treatment should be
based on processes)
● Availability: Available and unavailable
energy: availability of a closed and open
system, Availability of work and heat
reservoirs,
● Anergy and Exergy.

9. Basic Concepts:
What is Thermodynamics?
oThermodynamics is a science dealing with energy and its transformation.
o It deals with equilibrium and feasibility of a process.
oIt also deals with the relations between heat and work and the properties of a system.
“It can be define as the study of energy, energy transformations
and its relation to matter.”

10. Terminology:
o Thermodynamic system – It‟s defined as a definite area or a space where some thermodynamic
process takes place. OR specific amount of matter on which we focus our attention.
o Surroundings – Boundaries and anything outside the boundaries is called surroundings.
o Boundary- The real or imaginary surface that separates the system from its surroundings. The
boundaries of a system can be fixed or movable. Mathematically, the boundary has zero thickness, no
mass, and no volume.
SYSTEM
BOUNDARY
SURROUNDING

11. Terminology:
1. Closed system- fixed amount of mass. Only energy(heat or work), can cross the boundary.
2. Open system- both mass and energy can cross the boundary of a control volume.
3. Isolated system- fixed mass and no energy (heat or work) cross its boundary.

12. Terminology:
Systems may also be classified as;
I. Homogeneous system In this system the mass is uniformly distributed throughout the system value.
Examples : Mixture of air and water vapour, water plus nitric acid and octane plus heptane.
II. Heterogeneous system in this system the mass is not uniformly distributed throughout the system
volume. Examples : Water plus steam, ice plus water and water plus oil.
Control volume:
oControl volume is an arbitrary selected zone that surrounds the device under consideration. The surface of
these control value is referred to as control surface.
oA control volume is specified when an analysis is to be made that involves a flow of mass.
oThe control volume is separated from the surroundings by a control surface, which is analogous to the
boundary of a system; however, mass transfer may occur across the control surface.
oThe control volume may move in space and may have its volume change with time. It is not necessary that
the volume of a control volume be fixed, although in many cases a stationary control volume can be used.

13. Thermodynamic analysis of air compressor using control volume

14. Terminology:
ENERGY :
Ability to do a work is called energy. Thus we say that a moving object posses some energy.
Energy Due to
1.External Energy
Potential
Kinetic
Elevation of mass
Velocity of mass
2.Internal Energy
a)Molecular
Potential
Kinetic
Intermolecular forces
Molecular position
Molecular motion
b)Chemical Change in molecular
composition
c)Nuclear Changes in atomic composition

15. Terminology:
HEAT & WORK:
oA closed system interact with its surrounding or other systems in two ways;
By work transfer
By heat transfer
o Heat and work both are forms of an energy.
o Both are path functions, so both are not a properties of a system.

16. Terminology:
.
PROPERTY of a system:
A property of a system is a characteristic of the system which depends upon its state, but not upon
how the state is reached. There are two types of property :
1. Intensive properties : These properties do not depend on the mass of the system. Examples : Temperature
and pressure.
2. Extensive properties: These properties depend on the mass of the system. Example : Volume. Extensive
properties are often divided by mass associated with them to obtain the intensive properties. For example, if
the volume of a system of mass m is V, then the specific volume of matter within the system is
V/m = v
which is an intensive property.

17. Terminology:
Different properties of a system:
1. Specific Volume: Volume per unit mass.
2. Density: Mass per unit volume
3. Relative density: Ratio of density of a substance to density of water or air.
4. Pressure: Normal force per unit area.
Gauge pressure
Vaccum pressure
Atmospheric pressure (1.01325bar= 760mm of Hg= 101.325KPa)
Absolute pressure Pabs= Patm ± Pgauge (or) Pvaccum
Patm
Pabs
+ve Pgauge
-ve Pvaccum

18. 1. An isolated thermodynamic system execute a process. Choose the correct statement (s) from
the following (GATE ME 1999)
a)No heat transferred
b)No work is done
c)No mass flows across the boundary of the system
d)No chemical reaction takes place within the system
2. Heat and work are (GATE ME 2011)
a) intensive properties
b) extensive properties
c) point functions
d) path function
3. Select intensive and extensive properties from below list;
Specific enthalpy, total entropy, volume, specific volume, density, temperature

19. Terminology:
.
 STATE of a system:
State is the condition of the system at an instant of time as described or measured by its
properties. Or each unique condition of a system is called a state.
It follows from the definition of state that each property has a single value at each state. Stated differently, all
properties are point functions. Therefore, all properties are identical for identical states. Therefore, any
variable whose change is fixed by the end states is a property.

20. Terminology:
.
 Equilibrium state a system:
A system is in thermodynamic equilibrium if the temperature and pressure at all points are same
; there should be no velocity gradient ; the chemical equilibrium is also necessary.
In a state of equilibrium the properties of a system are uniform and only one value can be assigned
to each property.
Thus for attaining a state of thermodynamic equilibrium the following three types of equilibrium
states must be achieved :
1. Thermal equilibrium. The temperature of the system does not
change with time and has same value at all points of the system.
2. Mechanical equilibrium. There are no unbalanced forces
within the system or between the surroundings.
3. Chemical equilibrium. No chemical reaction takes place in
the system and the chemical composition which is same
throughout the system does not vary with time.

21. Terminology:
.
 Thermodynamic Process:
A process occurs when the system undergoes a change in a state or an energy transfer at a steady
state.
A process may be flow process or non-flow process.
Quasi-static process.: Quasi means „almost‟.
A quasi-static process is also called a
reversible process. This process is a succession
of equilibrium states and infinite slowness is
its characteristic feature.
Here A and B are two processes.
Cycle: Any process or series of
processes whose end states are identical is
termed a cycle.
1-A-2-B-1 = Thermodynamic
cycle

22. Terminology:
Different types of processes;
1)Const. Volume/ isochoric process:
-Temperature and Pressure will increase
-No change in volume and No work done by gas
-Governed by Gay-Lussac law
2) Const. Pressure/ isobaric process:
- Temperature and volume will increase
- Increase in internal energy
-Governed by Charles law
3)Constant temperature/ isothermal process:
- No change in internal energy
-No change in Temperature
4) Adiabatic/ isentropic process:
- No heat leaves or enters the gas
- Temperature of the gas changes
-Change in internal energy is equal to the work done

23. Terminology:
5)Polytropic process:
- It is general law of expansion and compression of the
gases.
p.v^n = Constant
6) Free expansion:
- When a fluid Is allowed to expand suddenly into a vacuum chamber through on orifice of large dimensions.
Q = 0, W = 0, and dU = 0.
7) Throttling process: When a gas expands through an small opening or nozze, such as a narrow
throat or slightly opened valve.

24. Terminology:
1) Reversible cycle: The initial conditions are restored at the end of
the cycle.
- There should not be any loss of heat due to friction, radiation or conduction.
- Heat pump operates reversed cycle and regarded as refrigerator, because it pumps heat from the cold
body to the hot body.
- constant volume, constant pressure, constant temperature, adiabatic and polytropic are all reversible
processes.
2) Irreversible cycle: In it initial conditions are not restored at the end of the cycle.
- There is loss of heat due to friction, radiation or conduction.
- Causes are:-
(a) mechanical and fluid friction
(b) unrestricted expansion
(c) heat transfer with temperature difference
-Throttling is irreversible process.

25. Terminology:
 Perfect/ Ideal gas laws:
1) Boyle‟s law- “The absolute pressure of a given mass of perfect gas varies inversely as its volume, when
the temperature remain constant”. Mathematically
pv = constant (T= const.)
2) Charles law- “The volume of a given mass of a perfect gas varies directly as its absolute
temperature, when the pressure remains constant”.
Mathematically, V/T = constant (p= const.)
3) Gay-lussac law- “The absolute pressure of a given mass of a perfect gas varies directly as its absolute
temperature when volume is constant.”
Mathematically, P/T = constant (v= const.)
PV = mRT
P = (m/V) RT
P = ρ RT
As v = (V/m)
Pv = RT n=nos. of moles
PV= n R‟T (R=R‟/M n=m/M)

26. Terminology:

27. Terminology:
1. THE ZEROTH LAW OF THERMODYNAMICS:If two bodies are in thermal equilibrium with a third body,
they are also in thermal equilibrium with each other.
By replacing the third body with a thermometer, the zeroth law can be restated as two bodies are in thermal
equilibrium if both have the same temperature, even if they are not in contact.

28. Terminology:
X1
X

29. Terminology:
 FIRST LAW OF THERMODYNAMICS:
“When a system undergoes a thermodynamic cycle then the net heat supplied to the system from the
surroundings is equal to net work done by the system on its surroundings.
dQ = dW
The First Law of Thermodynamics may also be stated as follows : “Heat and work are mutually convertible
but since energy can neither be created nor destroyed, the total energy associated with an energy conversion
remains constant”.
Or
“No machine can produce energy without corresponding expenditure of energy, i.e., it is impossible to
construct a perpetual motion machine of first kind”.

30. Terminology:
 SECOND LAW OF THERMODYNAMICS:
1. Clausius Statement
“It is impossible for a self acting machine working in a cyclic process unaided by any external agency, to
convey heat from a body at a lower temperature to a body at a higher temperature”.
In other words, heat of, itself, cannot flow from a colder to a hotter body.

31. Terminology:
 SECOND LAW OF THERMODYNAMICS:
2. Kelvin-Planck Statement
“It is impossible to construct an engine, which while operating in a cycle produces no other effect except to
extract heat from a single reservoir and do equivalent amount of work”.
Although the Clausius and Kelvin-Planck statements appear to be different, they are really equivalent in the
sense that a violation of either statement implies violation of other.

32. Terminology:
Heat Engine, Heat pump and Refrigerator

33. Absolute Thermodynamic Temperature Scale:
The efficiency of any heat engine receiving heat Q1 and rejects heat Q2 is given by;
So as we know efficiency of carnot cycle is independent of working fluid, its only depends on temperature f
reservoirs.

35. So by using triple point of water as a reference temp. we can
find out any absolute temperature.

36. Such a cycle is impossible, since net work being
produced in a cycle by a heat engine by exchanging
heat with a single reservoir in the process AB,
which violets Kelvin-Planks statement of second
law.
Through one point, there can pass only one
reversible adiabatic.

37. CLAUSIUS THEOREM :
It states “a reversible line can be replaced by two reversible adiabatic line & one reversible isothermal line.”
Process i-f Qif = Uf – Ui + Wif
Process i-a-b-f Qiabf = Uf – Ui +Wiabf
Since Wif =W iabf
Qif = Qiabf
= Qia + Qab + Qbf
Since Qia = 0 & Qbf = 0
Qif = Qab

38. CLAUSIUS THEOREM :

39. Entropy- Property of a System:

40. Entropy- Property of a System:

41. Clausius Inequality:

42. Clausius Inequality:
for any process AB, reversible or irreversible.
Since entropy is a property and the cyclic integral of
any property is zero.
This equation is known as the Clausius inequality. It
provides the criterion of the reversibility of a cycle.

43. Clausius Inequality:
the cycle is reversible,
the cycle is irreversible and possible
the cycle is impossible, since it violates the second law.

44. T-s planes:
The area under the curve is equal to the heat
transferred in the process.

46. h-s planes or Mollier Diagram:
This diagram has a series of
• Constant Temperature Lines,
• Constant Pressure Lines,
• Constant Quality Lines,
• Constant Volume Lines.
The Mollier diagram is used
only when quality is greater than
50% and for superheated steam.
For any state, at least two
properties should be known to
determine the other unknown
properties of steam at that state.

47. Entropy change in Reversible & Irreversible process:
For any process undergone by a system,
Consider one cycle, where A and B are reversible processes and C is an
irreversible process.
For the reversible cycle consisting of reversible processes A and B

48. Entropy change in Reversible & Irreversible process:
For the irreversible cycle consisting of A and C, by the inequality of
Clausius,
Since the path B is reversible Since entropy is a property, entropy changes for the paths B and C would
be the same. Therefore,

49. Entropy change in Reversible & Irreversible process:
Thus, for any irreversible process,
Therefore, for the general case, we can write
for any reversible process,
The equality sign holds good for a reversible process and
the inequality sign for an irreversible process.

50. Increase of Entropy Principle:
For any infinitesimal process undergone by a system,
= sign for reversible process
˃ sign for irreversible process
For an isolated system which does not undergo any energy interaction with
the surroundings, dQ = 0
It is thus proved that the entropy of an isolated system can never decrease.
It always increases and remains constant only when the process is
reversible. This is known as the principle of increase of entropy, or simply
the entropy principle.
Rudolf Clausius summarized the first and second laws of thermodynamics in the following words:
1. The energy of the world (universe) is constant.
2. The entropy of the world tends towards a maximum.

51. Increase of Entropy Principle:
The entropy of an isolated system always increases and becomes a maximum at the state of
equilibrium. When the system is at equilibrium, any conceivable change in entropy would be
zero.

53. One kg of water at 0°C is brought into contact with a heat reservoir at 90°C. When the
water has reached 90°C, find : (i) Entropy change of water ; (ii) Entropy change of the
heat reservoir ; (iii) Entropy change of the universe.

54. General Case for Change of Entropy of a Gas in Closed System:
Let 1 kg of gas at a pressure p1, volume v1, absolute temperature T1 and entropy s1, be heated
such that its final pressure, volume, absolute temperature and entropy are p2, v2, T2 and s2
respectively. Then by law of conservation of energy,
dQ = du + dW
where, dQ = Small change of heat,
du = Small internal energy, and
dW = Small change of work done (pdv).

55. General Case for Change of Entropy of a Gas in Closed System:

56. General Case for Change of Entropy of a Gas in Closed System:

57. General Case for Change of Entropy of a Gas in Closed System:

58. General Case for Change of Entropy of a Gas in Open System:
The net change of entropy of a system due to mass transport is equal to the difference between the product of
the mass and its specific entropy at the inlet and at the outlet of the system. Therefore, the total change of
entropy of the system during a small interval is given by;
In equation entropy flow into the system is considered positive and entropy out-flow is considered negative.
The equality sign is applicable to reversible process in which the heat interactions and mass transport to and
from the system is accomplished reversibly. The inequality sign is applicable to irreversible processes.

59. General Case for Change of Entropy of a Gas in Open System:
In a steady-state, steady flow process, the rate of change of entropy of the system becomes zero.

61. AVAILABILITY

62. Sources of energy can be divided into two
groups as shown below:
Energy of which only a certain portion can be converted into
mechanical work is called low grade energy.
•Examples of Low grade energy are:
1.Heat or Thermal Energy
2.Heat derived from combustion of fossil fuels
3.Heat derived from nuclear fission or fusion.

63. AVAILABLE
ENERGY
 The maximum work output
obtainable from a certain heat input
in a cyclic heat engine is called
available energy (A.E.).
 It is also called Exergy.
 The process will terminate when the
pressure and temperature of the
system and surrounding are equal.
This state is referred as dead state.
 Greater the deviation of the system
from the dead state indicates greater
availability.
 The minimum energy that has to be
rejected to the sink as per Second law
of Thermodynamics is called
Unavailable Energy.
 It is also called Anergy.
 The portion of energy not available for
conversion is called anergy.
 Mathematically;
Anergy = L.G.Energy – Exergy.
UNAVAILABLE ENERGY

64. DEAD STATE
Dead state refers to the state at which system and the environment are at mechanical,
thermal and chemical equilibrium. Thus neither there can be any spontaneous change
within the system or within the environment, nor any spontaneous interaction between the
two.

65. AVAILABILITY OF A NON FLOW / CLOSED SYSTEM
Consider a piston cylinder arrangement in which the fluid at P1 V1
T1 expands reversibly to the environmental state with parameter po
Vo To. The following energy interaction take place:
•The fluid expands and expansion work Wexp is obtained. From the
principle of energy conservation
δQ = δW + dU
we get,
-Q = Wexp + Uo – U1
The heat interaction is negative as it leaves the system
Wexp = U1 -Uo –Q
• The heat Q rejected by the piston cylinder assembly may be made
to run reversible heat engine . The output from the reversible engine
equals
• Weng = Q[1-To/T1] = Q – To(S1-So)
•The sum of total Wexp and Weng gives maximum work obtainable
from the arrangement
Wmax = U1 – Uo – To(S1- So)

66. AVAILABILITY OF A NON FLOW / CLOSED SYSTEM
As we know the piston expands hence doing positive amount of work
on surroundings which is equal to
Wsurr = po(Vo-V1)
Maximum work available or useful work
Wnet= Wmax – Wsurr
=(U1 + PoV1-ToS1) – (Uo+ PoVo – ToSo)
= A1 – Ao
Where A =(U +PoV-ToS) is known as non flow availability function.
It is composite property of system and surroundings. The term U- TS
is called Helmholtz Function.

67. AVAILABILITY OF A FLOW / OPEN SYSTEM
For previous system, Steady Flow Equation may be written as:
U1+ p1V1 + (ci)/2 +gz1 –Q = Uo+poVo+ (co)/2 +gzo+Ws
Where, U = internal energy,
v = specific volume,
h = specific enthalpy,
p = pressure,
c = velocity,
z = location.
Neglecting potential and kinetic energy changes,
U1+ p1V1 -Q = Uo+ po Vo +Ws
H1 – Q = Ho + Ws
Shaft work, Ws = ( H1 – Ho) - Q

68. AVAILABILITY OF A FLOW / OPEN SYSTEM
The heat rejected by the system may be made to run this reversible heat engine. The output from this engine
equals:
Weng = Q[1-To/T1] = Q – To(S1-So)
Wnet = Ws + Weng = (H1 - ToS1) – (Ho – ToSo)
=B1 - Bo
Where, B = (H- ToS) is known as Steady flow availability function.
It is a composite property of a system and surroundings too . It is also known as, Darrieus function and the
Keenam function.
The term (H –TS) is called Gibb‟s function.

69. AVAILABLE AND UNAVAILABLE ENERGY