Comparison of Vapor Absorption System with Vapor Compression System

Comparison of Vapor Absorption System with Vapor Compression System can be done in 9 aspects, they are 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	Vapor absorption system takes in low grade energy such as waste heat from furnace, exhaust team or solar heat for its operations.	Vapor compression system takes in high grade such as electrical or mechanical energy for its operation of compressor used in the cycle.
2	Moving part	It uses a small pump as moving part, which is 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, with little decrease in refrigerant capacity.	The refrigerant capacity decreases with lowered evaporator pressure.
4	Load variation	The performance of vapor absorption system does not change with load variation	The performance of vapor compressing system is very poor at partial load.
5	Evaporator exit	In vapor absorption system, the liquid refrigerant leaving the evaporator does not put 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 refrigerant, thus the lowest temperature attained is above 0°C.	With cascading, the temperature can be lowered upto -150°C or even less temperature.
7	Coefficient of Performance	The COP of the system is poor.	The COP of the system is excellent.
8	Capacity	It can built in capacities well above 1000 TR.	For a single compression system, it is not possible to have a system with more than 1000 TR capacity.
9	Refrigerant	Water or ammonia is used as refrigerant.	Chloroflourocarbon, hydroflorocarbon and hydrochlorofluorocarbon are used in most of the systems.