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Room AC System Or Unitary AC System And Central AC System :

ROOM AC SYSTEM OR UNITARY AC SYSTEM :

This is the simplest type of air conditioning system, assembled inside a casing. 

The unit consists of :

 i) Refrigeration system (involving the refrigerant),

ii) Control System ( Thermostat and selector switch ).

iii) Electrical protection system (motor overload switches and winding protection thermostat on the compressor motor),

iv) Air circulation System ( Fan motor, Centrifugal blower ),

v) Exhaust System . 



The working of this system can be divided into various circuits. They are,

I) Room air circuit :

  * Air from the room to be conditioned is drawn by a fan through a filter.

  * The hot air is passed through evaporator and gets cooled.

  * This cool air is passed to the room thereby makes it conditioned.

II) Refrigerant circuit :

  * The refrigerant (which was liquid) becomes evaporated by the heat given by the uncooled room air.

  * This vapor is compressed in the compressor and goes to the condenser, where it becomes liquid again.

  * In the capillary, it expands and enters the evaporator, where by receiving the room heat it becomes  vapor.

III) Condenser Circuit :

  * To cool the hot refrigerant vapor, air is drawn from outside by a fan and passed through the  condenser.

IV) Fresh Air - Room Air Mixing Circuit :

  * Fresh Air is admitted through a damper and is mixed with the return air from room.

 * This mixture is sent through the evaporator coil, gets cooled and passed to the room.

 * This filter, mounted in front of  the evaporator coil filters room air - fresh mixture.

 * This helps in keeping the fins and tubes clean to obtain optimum heat transfer from the coil. 


CENTRAL A/C SYSTEM : 

In a central System , all the components of the a/c system are grouped together in one central room and conditioned air is distributed from the central room to the required places through ducts. This system of central air conditioning is generally opted for the load above 25tons of refrigeration and 2500 m3/min of  conditioned air.  




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