Difference Between the Vapor Compression Refrigeration System and the Vapor Absorption Refrigeration System
By Laura Lee - August 31, 2022

Refrigeration systems are essential processes for industry and home applications because they help cool down or maintain the desired room temperature. All refrigeration systems work by transferring heat, moving it from one location to another, thus cooling that location and reversing the natural flow of heat with energy. However, how this occurs differs between different types of refrigeration systems. Of the four types, Vapor Compression and Vapor Absorption Systems are similar but still have differences.

Table Summary

Energy input is mechanical from an electric motorEnergy input is thermal
Refrigerant is compressed Refrigerant is heated and then absorbed
Includes five simple parts for each stage of the cycleThe compressor stage alone involves more than two extra parts.
There is only water vapor as a refrigerantWater vapor refrigerant is later dissolved in ammonia.
Noise production due to compressorNo noise production as there is no compressor
It is used in home cooling appliancesIt is used in bigger tonnage plants


Vapor compression refrigeration involves: compressing a vapor, condensing it with water or air, and expanding it to low pressure and temperature via a valve or an engine with power takeoff. This is divided into four stages: compression, condensation, expansion, and evaporation.

Vapor absorption refrigeration works on a slightly different principle compared to VAR. In the compression stage of VAR, there is no single compressor. The compressor is replaced by a generator, absorber, pump, and pressure-reducing valve. There are also auxiliary processes that require an analyzer and rectifier.


The first differentiating factor between VCRS and VARS is in the energy input. The energy driving VCRS is supplied mechanically by the action of an electric motor. In VARS, energy is provided thermally by water evaporation by solar energy, waste heat, or some other heat source. Also, while only water vapor acts as a refrigerant in the VCRS, the water vapor in VARS is first dissolved in an ammonia solution at the absorber. VCRS also has a higher CoP in the compression stage than VARS.