This is also called as window type room air-conditioner because it can be accommodated in window of walls. This unit is suitable for cooling the rooms in hot summer.
The window air-conditioner works on the vapour compression refrigeration cycle.
The basic components of a window air-conditioner are compressor, condenser, a capillary tube and an evaporator, in addition filters, accumulators, motors, fans and electrical controls. This unit consists of
1. A cooling system to cool and dehumidify the air which includes a condenser, a compressor and a refrigerant coil.
2. A filter to remove any impurities in the air. The filter is finished of with mesh, glass wool or fibre.
3. A fan and adjustable grills to circulate the air.
4. Controls to regulate equipment operation.
The high-pressure refrigerant which comes out of the compressor is condensed in the condenser using ambient air a coolant. The liquid refrigerant is expanded in a capillary tube and then enters the evaporator. Here, it evaporates and roots the refrigeration effect. Then fan blows the fresh air over the evaporator coil, which cools the air. The cool air is supplied to the room. Meanwhile, refrigerant from the evaporator enters the compressor to be compressed and the cycle repeats itself. The return air from the room is exhausted by the evaporator fan be blowing air over the condenser coil, where it picks up heat from the refrigerant.
The compressor used in a window air-conditioner is hermetic type, which is sealed in a casing with a motor. The condenser coil is a continuous copper coil with aluminium fins. The capillary tube is 40cm long, usually with 0.75mm diameter. Evaporator coil is also made of copper with aluminium fins. Dampers and louvers are provided for intake and exhaust on both sides of the air-conditioner casing.
A cone ton window air-conditioner circulated 4m³/min of air in the room. Some fraction of air is fresh, whereas some faction of air is recirculated. Filters are used to filter air entering the air-conditioning unit. The filter is plastic foam or metallic mat type. The controls used by the unit are
a) Thermostat Control: This is used to set the room air temperature. Usually it is a bimetallic strip.
b) Master Control: It is an electrical switch used to stop or start the compressor motor.
The installation of the unit is done either in the wall or by using external brackets or locating it inside the room with exhaust flush to the window. In either case, the condenser should be facing outside and the evaporator should be facing inside. It is advisable to install the unit for a minimum sun exposure as sun’s rays can diminish the efficiency of the condenser. The air louver inlets should not be blocked and provision for draining of the condensate must be provided. Maintenance of the window air-conditioner should include interrupted cleaning, replacing filters and air seals and lubrication of fans.