Comparison of Vapor Absorption System with Vapor Compression System

Comparison of the Vapor Absorption System with the Vapor Compression System can be made in 9 aspects: energy input, moving part, evaporator pressure, load variation, evaporator exit, coefficient of performance, capacity, refrigerant, and lowest temperatures.


S.no
Aspect
Vapor Absorption System
Vapor Compression System
1 Energy Input The vapor absorption system uses low-grade energy, such as waste heat from the furnace, exhaust steam, or solar heat, for its operations. A vapor compression system takes in high grade, such as electrical or mechanical energy, to operate the compressor used in the cycle.
2 Moving part It uses a small pump as a moving part run by a small motor. It uses a compressor driven by an electric motor or engine.
3 Evaporator pressure It can operate with reduced evaporator pressure and a decrease in refrigerant capacity. The refrigerant capacity decreases with lowered evaporator pressure.
4 Load variation The performance of the vapor absorption system does not change with load variation The performance of the vapor compressing system is very poor at partial load.
5 Evaporator exit In a vapor absorption system, the liquid refrigerant leaving the evaporator does not have any bad effect on the system except to reduce the refrigerant effect. In a vapor compression system, it is desirable to superheat vapor before leaving the evaporator so no liquid can enter the compressor.
6 Lowest temperature Since water is used as a refrigerant, thus the lowest temperature attained is above 0°C. With cascading, the temperature can be lowered to -150°C or even less.
7 Coefficient of Performance The COP of the system is poor. The COP of the system is excellent.
8 Capacity It can build in capacities well above 1000 TR. For a single compression system, having a system with more than 1000 TR capacity is impossible.
9 Refrigerant Water or ammonia is used as a refrigerant. Chlorofluorocarbons, hydrofluorocarbon, and hydrochlorofluorocarbon are used in most of the systems.

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