appplied thermodynamics

2. CARNOT CYCLE
The Most Efficient Ever But Ideal

3. GROUP MEMBERS:
 MUHAMMAD OMER (2015-EE-468)
 WALEED TARIQ (2015-EE-406)
 ZAIN-UL-ABIDIN (2015-EE-456)
 RIDA FATIMA (2015-EE-462)
 USAMA BUTT (2015-EE-492)

4. CONTENTS
 INTRODUCTION
 HISTORY
 ASSUMPTIONS
 P-V DIAGRAM
 EFFICIENCY
 LIMITATIONS
 CONCLUSIONS

5. INTRODUCTION
 The most powerful and efficient heat cycle
consisting of two isothermal and two
adiabatic processes.
 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”.

6. 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.
1796-1832

7. COMMON ASSUMPTIONS OF CARNOT
CYCLE
 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.

8. P-V DIAGRAM
Processes:-
 Isothermal Expansion
(1-2)
 Adiabatic Expansion
(2-3)
 Isothermal
Compression
(3-4)
 Adiabatic
Compression
(4-1)

9. 4 STEPS
OF
CARNOT
CYCLE

10. ELABORATION
 The fig. 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 TH To TL.
 Two phases mixture flows through condenser
where heat rejection occurs at constant
temperature TL.

11. ELABORATION
 The mixture (liquid-vapour) enters the
pump (or compressor) and its pressure
increases.This is an adiabatic process and
requires input work.
 The saturated liquid at high temperature
enters the boiler,where change of phase
occurs at constant temperature TH.

12. 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.

13. PROOF OF CARNOT THEOREM

14.  An impossible situation.
 A heat engine cannot drive a less efficient
heat engine.
 Voilation of 2nd Law of Thermodynamics.
 If ŋM > ŋL, then the net heat flow would be
backwards, i.e., into the hot reservoir.

15. PROOF OF CARNOT THEOREM FOR:
 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.”

16. EFFICIENCY OF CARNOT CYCLE
 Thermal efficiency of the Carnot cycle can
be calculated from:
th=1-(QL/QH)=1-(TL/TH).
So called the Carnot efficiency.
 The higher the temperature of the low-
temperature sink, the more difficult for a
heat engine to transfer heat into it.Thus,
lower thermal efficiency also.

17. LIMITATIONS OF 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.

18. CONCLUSIONS
 We can say that Carnot Engine is one of the
most efficient one but it’s ideal one.
 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   