Vapour Absorption Refrigeration System

The vapour absorption refrigeration system consists of

Absorber: Absorption of refrigerant vapour by a suitable absorbent or adsorbent, forming a strong or rich solution of the refrigerant in the absorbent/ adsorbent

Pump: Pumping of the rich solution and raising its pressure to the pressure of the condenser

Generator: Distillation of the vapour from the rich solution leaving the poor solution for recycling

The absorption chiller is a machine, which produces chilled water by using heat such as steam, hot water, gas, oil etc. Chilled water is produced based on the principle that liquid (i.e. refrigerant, which evaporates at a low temperature) absorbs heat from its surroundings when it evaporates. Pure water is used as refrigerant and lithium bromide solution is used as absorbent.

Heat for the vapour absorption refrigeration system can be provided by waste heat extracted from the process, diesel generator sets etc. In that case absorption systems require electricity for running pumps only. Depending on the temperature required and the power cost, it may even be economical to generate heat /steam to operate the absorption system.


The refrigerant (water) evaporates at around 4oC under a high vacuum condition of 754 mm Hg in the evaporator.

Chilled water goes through heat exchanger tubes in the evaporator and transfers heat to the evaporated refrigerant.

The evaporated refrigerant (vapor) turns into liquid again, while the latent heat from this vaporization process cools the chilled water (in the diagram from 12 oC to 7 oC). The chilled water is then used for cooling purposes.


In order to keep evaporating, the refrigerant vapor must be discharged from the evaporator and refrigerant (water) must be supplied. The refrigerant vapor is absorbed into lithium bromide solution, which is convenient to absorb the refrigerant vapor in the absorber. The heat generated in the absorption process is continuously removed from the system by cooling water. The absorption also maintains the vacuum inside the evaporator.

High Pressure Generator

As lithium bromide solution is diluted, the ability to absorb the refrigerant vapor reduces. In order to keep the absorption process going, the diluted lithium bromide solution must be concentrated again.

An absorption chiller is provided with a solution concentrating system, called a generator. Heating media such as steam, hot water, gas or oil perform the function of concentrating solutions.

The concentrated solution is returned to the absorber to absorb refrigerant vapor again.


To complete the refrigeration cycle, and thereby ensuring the refrigeration takes place continuously, the following two functions are required

1. To concentrate and liquefy the evaporated refrigerant vapor, which is generated in the high pressure generator.

2. To supply the condensed water to the evaporator as refrigerant (water)

For these two functions a condenser is installed.

Post a Comment

>> Your Comments are always appreciated...
>> Discussion is an exchange of knowledge It Make the Mariner Perfect.... Please Discuss below...

Previous Post Next Post