introduction to thermodynamics, 2nd law, rankine cycke, carnot cycle

1. “Start With The Name Of
Almighty Allah Who Is Most
Gracious And Most Merciful”
Asalam_O_Alikum1

2. Group members
• Attiya-Tur-Rehman 19-PG-04
• Mirza Osama Baig 19-PG-11
• Abdul Rafay 19-PG-14
• Rahzan Ali 19-PG-15
• Zubair Khan 19-PG-30
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3. Objective
• What is Thermodynamics?
• History of Thermodynamics
• Laws of Thermodynamics
Introduction
• Kelvin-Plank Statement
• Clausius Statement
2nd Law of
Thermodynamics
• What are the Thermodynamic cycles?
• Carnot cycle
• Rankine Cycle
Thermodynamics
cycles
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4. Introduction to Thermodynamics

5. Introduction to
Thermodynamics
“Thermodynamics
can be defined as
science of
energy”
Energy can be
viewed as the
ability to cause
change.
Therms = Heat Dynamics = Power
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6. Introduction to Thermodynamics
Principle of
thermodynamics have
been in existence since
the creation of universe.
Thermodynamics did not
emerge as science, until
the construction of the
successful heat engines
in 1697 and 1712.
These engines were very
slow and inefficient, but
they opened the way for
the development of new
science.
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7. Introduction to Thermodynamics
The first and second law of thermodynamics appeared simultaneously in 1850s.
Primarily out of work of William Rankine, Rudolph Clausius and lord Kelvin.
The 1st law of thermodynamics is simply an expression of conversion of energy.
The 2nd law of thermodynamics states that energy has quality as well as quantity,
and actual process occur in the direction of decreasing quality of energy.
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8. Introduction to Thermodynamics
All activities in
nature involve
some interaction
between energy
and matter, thus , it
is hard to imagine
an area that does
not relate to
thermodynamic in
some manner.
Application areas
of
Thermodynamics:
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9. Introduction to Thermodynamics9
Fig (a) Fig (b)

10. 2nd Law of Thermodynamics
It apply on irreversible process.
It is based on experimental observation.
• Identify direction of process.
• Determine the quality as well as degree of degradation of energy during
a process.
• Determine the theoretical limits for the performance of commonly used
engineering system, such as refrigerator.
Application of 2nd law of thermodynamics.
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11. 2nd Law of Thermodynamics
• No heat engine has thermal
efficiency of 100%.
• All heat can not be converted into
work.
• As for power plant to operate, the
working fluid must exchange heat
with the environment as well as
furnace.
• This statement involve work
generating cycles such as Heat
engines.
Kelvin-
Plank
Statement
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12. 2nd Law of Thermodynamics
There are several types of heat engines, but they are
characterized by the following:
- They all receive heat from a high-temperature source (oil
furnace, nuclear reactor, etc.)
- They convert part of heat to work.
- They reject the remaining waste heat to a low-temperature sink
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13. 2nd Law of Thermodynamics
Clausius
Statement
• It is impossible to transfer heat from
cold body to hot body without
external work.
• It includes work consuming cycles
such as refrigerator and heat pumps.
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14. 2nd Law of Thermodynamics
Heat pumps and
refrigerator both
transfer heat from
low temperature to
high temperature
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15. Thermodynamic Cycles
Heat engines are cyclic devices.
A cycle can only occur if it satisfies both 1st and 2nd law of thermodynamics.
Working fluid of a heat engine returns to its initial state at the end of cycle.
Reversible cycle that reverse without effecting its surrounding.
Reversible process are ideal process.
It define maximum efficiency as compare to any heat engine.
It work on Temperature difference.
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16. Thermodynamic Cycles16

17. Thermodynamic Cycle
Carnot Cycle
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18. Contents
Introduction.
Background.
Assumptions.
P-V diagram.
Efficiency.
Limitations.
Conclusion.
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19. Introduction
• The Carnot cycle , is a thermodynamic
process, that describes how a fluid is used to
convert thermal energy into work.
• This actually is the idealization because in
order to approach it’s efficiency the processes
involved must be reversible and involves no
change in entropy.
• A system undergoing Carnot cycle is called
“Carnot Engine
• It is related to the theory of heat engines with
maximum efficiency.
• It is a hypothetical cycle which is used to
compare other cycle.
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20. History
• Proposed by Nicolas Léonard Sadi Carnot in 1824.
• He was a French Engineer.
• Founder of the science of thermodynamics.
• First one to recognize the relationship between work and heat.
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21. Common elements of Carnot cycle
Working substances. (i.e. Air)
Heat source and heat sink.
Piston-Cylinder arrangement.
Diathermic cover (perfect heat conductor) and Adiabatic cover
(prefect heat insulator)
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22. Processes:
In one complete cycle of
operation, there are four
different thermodynamic
Processes:
Isothermal Expansion:
 (1-2) T = constant
Adiabatic Expansion:
 (2-3) Q = constant
Isothermal Compression:
 (3-4) T = constant
Adiabatic Compression:
 (4-1) Q = constant
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23. • Working substances is a perfect gas.
• There is no friction between the cylinder and piston.
• Walls of cylinder and piston are considered as perfect
heat insulator.
• Transfer of heat does not affect the temperature of
source or sink.
• Isothermal expansions and compressions are
considered quasi-equilibrium.
• No heat losses in pipes and other components.
• The cycles do not have any friction. Thus, no pressure
drops in the working fluid.
• Changes in kinetic and potential energies are
negligible.
Common assumptions
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24. Elaboration
Previous picture
shows the
schematic and
accompanying P-V
diagram of a
Carnot cycle
executed by water
steadily circulating
through a simple
vapor power plant.
The steam exiting
the boiler expands
adiabatically
through the turbine
and the work is
developed.
The steam
temperature
decreases from
HIGH To LOW
medium.
Two phases
mixture flows
through condenser
where heat
rejection occurs at
constant
temperature TL.
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25. Carnot Theorem
No real engine can be
more efficient than a
Carnot Engine
operating between
same two reservoirs.
All Carnot Engines
operating between
reservoirs at the same
temperature have the
same efficiency.
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26. Carnot Theorem
Reversible Engines:
“ All reversible engines that operate between the same two
heat reservoirs have the same efficiency.”
Irreversible Engines:
“ No irreversible engine is more efficient than the Carnot
engine operating between the same two reservoirs.
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27. Thermal efficiency of the Carnot
Efficiency of Carnot cycle = work done /heat
supplied and can be calculated from:
n=1-(QL/QH)=1-(TL/TH).
• Efficiency increase with decrease in temperature.
• Most engines have a thermodynamic limit of 37% (little bit higher for diesel
engines).
• Practical efficiency depends of temperature level and differences.
• Thermal efficiency can then be used to compare the efficiencies of other
cycles operating between the same two temperatures.
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28. Applications
All types of vehicles that we use, cars,
motorcycles, trucks, ships, aero planes, and
many other types of engines work, on the
basis of second law of thermodynamics and
Carnot Cycle. They may be using petrol
engine or diesel engine, but the law remains
the same.
All the refrigerators, deep freezers, industrial
refrigeration systems, all types of air-
conditioning systems, heat pumps, etc. work
on the basis of the Carnot cycle.
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29. Limitations of a Carnot Cycle
The isentropic process 1-2 is practically not achievable, as it is
difficult to handle two phase system.
If the steam quality is poor then process, 3-4 is difficult to carry out.
It is impossible to perform a frictionless process.
It is impossible to transfer the heat with out finite temperature
difference.
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30. Conclusion
We can say that Carnot Engine is one of the most efficient one but
it’s ideal one.
Carnot engine is purely an imaginary engine. But all real engines
are constructed based on Carnot cycle.
Let assume for a moment that it’s not an ideal cycle then what
would happen??
I think there will be no other engines, because after this gorgeous
thing there is no need.
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31. 31
Reverse Carnot Cycle

32. Thermodynamic Cycles
The Reversed Carnot cycle:
• Also known as Carnot refrigeration
cycle.
• Direction of Heat and work
interaction changed.
Practically the reversed Carnot
cycle can not be used for
refrigeration, as adiabatic
required high speed operation
and Isothermal required low
speed operation.
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33. Refrigeration Cycle
A major application area of
thermodynamics is refrigeration,
which is the transfer of heat from a
lower temperature region to a higher
temperature one. Devices that
produce refrigeration are called
refrigerators, and the cycles on
which they operate are called
refrigeration cycles.
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34. Thermodynamic Cycles34
The ideal vapor-compression cycle consists of four processes.
• 12 Isentropic compression
• 23 Constant pressure heat rejection in the condenser
• 34 Throttling in an expansion valve
• 41 Constant pressure heat addition in the evaporator

35. Refrigeration Cycle
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36. 36
Rankine Cycle

37. What is the power cycle?
Conversion of heat into work.
If we use vapor then it is called vapor power cycle.
Power is depend on the temperature difference
between heat source and cold sink
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38. Rankine Cycle
It is also known as vapor power cycle. It is the
modified practical cycle of Carnot cycle.
Working fluid continuously evaporate and
condense in closed loop.
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39. Rankine Cycle
Ideal Rankine cycle is reversible cycle which
include 4 processes.
• 12 Isentropic expansion in turbine (Q=0).
• 23 constant pressure heat rejection in condenser (W=0).
• 34 isentropic compression in pump (Q=0).
• 41 constant pressure heat addition in boiler (W=0).
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40. Rankine Cycle
Ideal Rankine Cycle Block Diagram
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41. Why we use Water as working fluid?
Non toxic
Net reactive
Highly abundant
Low cost
Good
thermodynamic
properties

42. Rankine Cycle
• As a result of irreversibilities in various
components. Fluid friction and heat loss
to the surroundings are the two
common source of irreversibilities.
• Fluid friction causes pressure drops in
the boiler, the condenser, and the
piping between various components.
Rankine
cycle Ideal
to Actual
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43. Rankine Cycle
Small increase in thermal efficiency can mean large savings from fuel requirement.
Increase the temperature of heat source and decrease the temperature of heat sink.
Lowering the condenser pressure.
Superheating the steam to High temperature
Increasing the boiler pressure.
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Increase efficiency of Rankine cycle.

44. Rankine Cycle
Steam power plants are
responsible for more electric
power in the world. In 2018, 90%
of total world electrical energy was
producing using Rankine cycle
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45. Rankine Cycle
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24
27
4 4
7
0
5
10
15
20
25
30
35
40
Oil Gas Coal Nuclear Renewable Hydro
Total production of electricity in year 2018
Total production
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46. References
Book  Thermodynamics by Yunus A. Cengel,
Michael A.Boles
Book  Applied Thermodynamics T.D Eastop, A
MacConkey.
YouTube Channels  Khan Academy, Gate
Academy.
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