As far as the functions are concerned, Air conditioning systems are classified as follows:

1) Comfort Air-Conditioning System: 

The purpose of a system is to create atmospheric conditions conducive to human health, comfort and efficiency.

2) Industrial Air-Conditioning: 

The purpose of these air-conditioning systems is to control atmospheric conditions primarily for the proper conduct of research and manufacturing process.

3) Summer Air-Conditioning Systems: 

For summer comfort cooling the air and the removal of excess moisture from the air is accomplished by condensation of water vapour in the air on cold coil surfaces.

4) Winter Air-Conditioning Systems: 

The major problems of winter air-conditioning are to heat the air and to bring moisture content up to an acceptable level. Heating is accomplished by electric heaters.

5) Year-round Air-Conditioning Systems: 

These systems are composed of heating and

cooling equipment with automatic controls and associated components to produce the required atmosphere conditions for human comfort at all times of the year. 

6) Unitary (Window) Air-conditioning System : 

The unitary or window type air conditioner is of small capacity upto two tones, used for air conditioning of rooms, small offices, operation theatres etc.

7) Central Air Conditioning system: 

The central system is used for air conditioning of large multi storyed buildings, etc. where a capacity required is around 50 to 100 tonnes. Central system is provided with a central automatic control point. The air after conditioning will be sent through ducts to various floors and rooms. Since the cooling and heating equipment is installed in one location rather than several locations, the maintenance of the system is easier. Also, better air distribution is possible.


It consists of dampers, air filter, cooling coil, spray type humidifier, heating coil and a fan. Atmospheric air flows through the dampers. The quantity of air depends upon the “load” and the dampers control it. Air then passes through the Air filter. The filter removes dirt, dust and other impurities.

A.C System Diagram

The air now passes over a cooling coil. So when air is cooled below its dew point temperature, the water vapour is removed from the air in the form of water droplets. The surface temperature of the cooling coil has to be maintained below the dew-point temperature of the atmospheric air to accomplish dehumidification. The quantity of water removed from air is collected in the sump and is drained.

The temperature of air leaving the cooling coil is lower than the ambient temperature for comfort. During the dry weather the spray type humidifier is used to increase the humidity of the conditioned air. During wet weather condition the relative humidity of the air is high, is controlled by the heating coil. For the comfort condition required is DBT around 23″ C and relative humidity 60% So the air is to be cooled and humidified to the comfort condition.

Now the conditioned air is supplied to the conditioned space by a fan and ducts.

See More: Vapour Compression Refrigeration System

See More: Water Cooling System

See More: Vapour Absorption Refrigerator System

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