rac

1. Btech Mech 6th SEM Major Assignment
Exergy Analysis of Vapor Compression Cycle
Vikas Mishra
K10947
Btech Mech 6th Sem

2. Exergy
• The term exergy maens the maximum useful work possilble during
a process that brings the system into equilibrium with a heat
reservoir. When the surroundings are the reservoir, exergy is the
potential of a system to cause a change as it achieves equilibrium
with its environment.

3. Refrigeration
• Refrigeration : The term refrigeration may be defined as the
process of removing heat from a substance under controlled
conditions.
• It also includes the process of reducing heat & maintaining the
temp. of a body below the general temp. of its surroundings.

4. Vapour Compression System
Low Pressure Side
High Pressure Side
Liquid receiver
Expansion
valve
Compressor
Evaporator
Liquid
Condenser
Heat in
Heat out
Hot Gas
Gas
4 numbers principle components :
(1)Evaporator
(2)Compressor
(3)Condenser
(4)Expansion Valve

5. Vapour Compression Refrigeration
• Highly compressed fluids tend to get colder when
allowed to expand
• If pressure high enough
• Compressed air hotter than source of cooling
• Expanded gas cooler than desired cold temperature

6. Vapour Compression Refrigeration
Two advantages
• Lot of heat can be removed (lot of thermal energy to
change liquid to vapour)
• Heat transfer rate remains high (temperature of
working fluid much lower than what is being cooled)

7. Vapour Compression Refrigeration
Refrigeration cycle
Condenser
Evaporator
High Pressure
Side
Low
Pressure
Side
Compressor
Expansion
Device
1 2
3
4

8. Vapour Compression Refrigeration
Refrigeration cycle
Low pressure liquid refrigerant in
evaporator absorbs heat and
changes to a gas
Condenser
Evaporator
High
Pressure
Side
Low
Pressure
Side
Compressor
Expansion
Device
1 2
3
4

9. 1) The evaporator coils are located in the compartment to be cooled.
2) The low pressure liquid refrigerant ,after passing through the
expansion valve, expands.
3) Takes in heat from the surrounding and evaporates.
4) The gas is then sucked up by the compressor.
5) The amount of heat added to the liquid to make it saturated and
change states is called Super Heat.
EVAPORATOR:

10. Vapour Compression Refrigeration
The superheated vapour enters the
compressor where its pressure is
raised
Condenser
Evaporator
High
Pressure
Side
Low
Pressure
Side
Compressor
Expansion
Device
1 2
3
4

11. The Compressor
• The compressor is the heart of the system. The compressor does just what it’s name
is. It compresses the low pressure refrigerant vapor from the evaporator and
compresses it into a high pressure vapor.
• The inlet to the compressor is called the Suction Line. It brings the low pressure vapor
into the compressor.
• After the compressor compresses the refrigerant into a high pressure Vapor, it
removes it to the outlet called the Discharge Line.

12. Vapour Compression Refrigeration
The high pressure superheated gas
is cooled in several stages in the
condenser
Condenser
Evaporator
High
Pressure
Side
Low
Pressure
Side
Compressor
Expansion
Device
1 2
3
4

13. The Condenser
The Discharge Line leaves the compressor and runs to the inlet of the condenser.
Because the refrigerant was compressed, it is a hot high pressure vapor (as pressure goes
up – temperature goes up).
The hot vapor enters the condenser and starts to flow through the tubes.
Since the air is cooler than the refrigerant, heat jumps from the tubing to the cooler air
(energy goes from hot to cold – latent heat).
As the heat is removed from the refrigerant, it reaches it’s saturated temperature and
starts to boil (change states), into a high pressure liquid.
The high pressure liquid leaves the condenser through the liquid line and travels to the
metering device. Sometimes running through a filter dryer first, to remove any dirt or
foreign particles.

14. Vapour Compression Refrigeration
Refrigeration cycle
Liquid passes through expansion device,
which reduces its pressure and controls the
flow into the evaporator
Condenser
Evaporator
High
Pressure
Side
Low
Pressure
Side
Compressor
Expansion
Device
1 2
3
4

15. Thermal expansion Valves
• EXPANSION:
1) The expansion valve acting as a regulating
valve, limits the amount of refrigerant
flowing through.
2) Resulting in reduction of pressure of the
liquid and expansion takes place.

16. Vapour Compression Refrigeration
Type of refrigerant
• Refrigerant determined by the required cooling
temperature
• Chlorinated fluorocarbons (CFCs) or freons: R-11, R-
12, R-21, R-22 and R-502