Refrigeration: Thermodynamics and Simple Vapor Compression
Refrigeration Cycles
Prof. U.S.P. Shet , Prof. T. Sundararajan and Prof. J.M . Mallikarjuna
6.5 Simple Vapor Compression Refrigeration System:
A simple vapor compression refrigeration system consists of the following equipments: i) Compressor ii) Condenser iii) Expansion valve iv) Evaporator.
B
COMPRESOR
C ∆Q1 200C
FLUID TO BE COOLED
EVAPORATOR (-300C)
w
CONDENSER (350C)
COOLING WATER
00C ∆Q2 A
EXPANSION VALVE
D
Fig.6.5. Simple vapour compression system
The schematic diagram of the arrangement is as shown in Fig.6.5. The low temperature, low pressure vapor at state B is compressed by a compressor to high temperature and pressure vapor at state C. This vapor is condensed into high pressure vapor at state D in the condenser and then passes through the expansion valve. Here, the vapor is throttled down to a low pressure liquid and passed on to an evaporator, where it absorbs heat from the surroundings from the circulating fluid (being refrigerated) and vaporizes into low pressure vapor at state B. The cycle then repeats. The exchange of energy is as follows:
Indian Institute of Technology Madras
Refrigeration Cycles
Prof. U.S.P. Shet , Prof. T. Sundararajan and Prof. J.M . Mallikarjuna
a) Compressor requires work, δw. The work is supplied to the system from the surroundings. b) During condensation, heat δQ1 the equivalent of latent heat of condensation etc, is lost from the refrigerator. c) During evaporation, heat δQ2 equivalent to latent heat of vaporization is absorbed by the refrigerant. d) There is no exchange of heat during throttling process through the expansion valve as this process occurs at constant enthalpy.
6.5.1 Simple Vapor Compression Cycle:
C" T T1 350c D C' C
-300C T2 T A B' B
B"
P
Q
R'
R
S
Fig.6.5.1. T-s diagram of refrigeration cycle
Figure 6.5.1 shows a simple vapor compression refrigeration cycle on T-s diagram for different compression processes. The cycle
Prof. U.S.P. Shet , Prof. T. Sundararajan and Prof. J.M . Mallikarjuna
6.5 Simple Vapor Compression Refrigeration System:
A simple vapor compression refrigeration system consists of the following equipments: i) Compressor ii) Condenser iii) Expansion valve iv) Evaporator.
B
COMPRESOR
C ∆Q1 200C
FLUID TO BE COOLED
EVAPORATOR (-300C)
w
CONDENSER (350C)
COOLING WATER
00C ∆Q2 A
EXPANSION VALVE
D
Fig.6.5. Simple vapour compression system
The schematic diagram of the arrangement is as shown in Fig.6.5. The low temperature, low pressure vapor at state B is compressed by a compressor to high temperature and pressure vapor at state C. This vapor is condensed into high pressure vapor at state D in the condenser and then passes through the expansion valve. Here, the vapor is throttled down to a low pressure liquid and passed on to an evaporator, where it absorbs heat from the surroundings from the circulating fluid (being refrigerated) and vaporizes into low pressure vapor at state B. The cycle then repeats. The exchange of energy is as follows:
Indian Institute of Technology Madras
Refrigeration Cycles
Prof. U.S.P. Shet , Prof. T. Sundararajan and Prof. J.M . Mallikarjuna
a) Compressor requires work, δw. The work is supplied to the system from the surroundings. b) During condensation, heat δQ1 the equivalent of latent heat of condensation etc, is lost from the refrigerator. c) During evaporation, heat δQ2 equivalent to latent heat of vaporization is absorbed by the refrigerant. d) There is no exchange of heat during throttling process through the expansion valve as this process occurs at constant enthalpy.
6.5.1 Simple Vapor Compression Cycle:
C" T T1 350c D C' C
-300C T2 T A B' B
B"
P
Q
R'
R
S
Fig.6.5.1. T-s diagram of refrigeration cycle
Figure 6.5.1 shows a simple vapor compression refrigeration cycle on T-s diagram for different compression processes. The cycle