Evaporator

Evaporator

The evaporator consists of a refrigerant coil mounted in a series of thin fins to provide a maximum amount of heat transfer in a minimum amount of space. It is housed in the air conditioning unit and all air entering the system passes across its coil.

The evaporator receives refrigerant from the thermostatic expansion valve as a low pressure cold atomised liquid. As this cold liquid passes through the evaporator coils, it absorbs heat from the surrounding air and changes into a low pressure warm vapour.

Expansion Valve

The expansion valve is the dividing point between the high and low pressure sides of the system. It automatically meters high pressure, warm liquid refrigerant via a metering orifice into the low pressure, cold side of the evaporator matrix. The valve senses outlet pipe temperature, inlet pipe pressure and regulates the flow of refrigerant into the evaporator to ensure that only vapourised refrigerant appears at the outlet.

Receiver-Drier

The receiver drier (Fig. 1) accepts high pressure warm refrigerant liquid from the condenser and delivers it via an expansion valve to the evaporator. It contains a quantity of molecular sieve desiccant to remove moisture from the refrigerant, and a filter to remove contaminants. It also provides a reservoir of refrigerant for the evaporator under varying operating conditions.