REFRIGERATION SYSTEMS: Vapour Compression System, Vapour absorption system ~ MECHTECH GURU

REFRIGERATION SYSTEMS: Vapour Compression System, Vapour absorption system


Refrigeration means the cooling of or removal of heat from a system. Refrigerators work mainly on two processes:

1. Vapour compression, and

2. Vapour absorption.

Simple Vapour Compression System:

In a simple vapour compression system the following fundamental processes are completed in one cycle:

1. Expansion 

2. Vapourisation 

3. Compression 

4. Condensation.

Simple vapour compression cycle.
Simple vapour compression cycle.

The vapour at low temperature and pressure (state ‘M’) enters the compressor where it is compressed isoentroprically and subsequently its temperature and pressure increase considerably (state ‘N’). This vapour after leaving the compressor enters the condenser where it is condensed into high pressure liquid (state ‘S’) and is collected in a receiver. From receiver it passes through the expansion valve, here it is throttled down to a lower pressure and has a low temperature (state ‘L’). After finding its way through expansion valve it finally passes on to evaporator where it extracts heat from the surroundings and vapourises to low pressure vapour (state ‘M’).

Domestic Refrigerator:

Refrigerators, these days, are becoming the common item for house hold use, vendor’s shop, hotels, motels, offices, laboratories, hospitals, chemists and druggists shops, studios etc.

They are manufactured in different size to meet the needs of various groups of people. 

They are usually rated with internal gross volume and the freezer volume. The freezer space is meant to preserve perishable products at a temperature much below 0°C such as fish, meat, chicken etc. and to produce ice and icecream as well.

The refrigerators in India are available in different sizes of various makes, i.e., 90, 100, 140, 160, 200, 250, 380 litres of gross volume. 

The freezers are usually provided at top portion of the refrigerator space occupying around one-tenth to one-third of the refrigerator volume. In some refrigerators, freezers are provided at the bottom.

A domestic refrigerator consists of the following two main parts 

1. The refrigeration system.

2. The insulated cabinet.

Fig. shows a flow diagram of a typical refrigeration system used in a domestic refrigerator.

A simple domestic refrigerator consists of a hermetic compressor placed in the cabinet base.

The condenser is installed at the back and the evaporator is placed inside the cabinet at the top.

The working of the refrigerator is as follows:

— The low pressure and low temperature refrigerant vapour (usually R12) is drawn through the suction line to the compressor. The accumulator provided between the suction line and the evaporator collects liquid refrigerant coming out of the evaporator due to incomplete evaporation, if any, prevents it from entering the compressor. The compressor then compresses the refrigerant vapour to a high pressure and high temperature. The compressed vapour flows through the discharge line into condenser (vertical natural draft, wire-tube type).

— In the condenser the vapour refrigerant at high pressure and at high temperature is condensed to the liquid refrigerant at high pressure and low temperature.

Domestic refrigerator
Domestic refrigerator

— The high pressure liquid refrigerant then flows through the filter and then enters the capillary tube (expansion device). The capillary tube is attached to the suction line as shown in Fig. The warm refrigerant passing through the capillary tube gives some of its heat to cold suction line vapour. This increases the heat absorbing quality of the liquid refrigerant slightly and increases the superheat of vapour entering the compressor. The capillary tube expands the liquid refrigerant at high pressure to the liquid refrigerant at low pressure so that a measured quantity of liquid refrigerant is passed into the evaporator.

— In the evaporator the liquid refrigerant gets evaporated by absorbing heat from the container/articles placed in the evaporative chamber and is sucked back into the compressor and the cycle is repeated.

Next Post »


Click here for comments
July 5, 2021 at 1:03 PM ×

Really Informative! This post gives a better idea about Refrigerants system. Thanks for the useful information. I hope you will share some more content. Please keep sharing!

July 5, 2021 at 11:44 PM ×

This article provided me with a wealth of information. The article is both educational and helpful. Thank you for providing this information. Keep up the good work. refrigeration installation