BASIC REFRIGERATION PRINCIPLES 2
30/03/2011
The Refrigeration Condenser
Refrigeration condensers are usually installed on the reinforced rooves of buildings, which enables the transfer of heat. The purpose of the refrigeration condenser is to extract heat from the refrigerant to the outside air. Fans mounted above the refrigeration condenser unit are used to draw air through the condenser coils.
The temperature of the high-pressure vapour determines the temperature at which the condensation begins. As heat has to flow from the condenser to the air, the condensation temperature must be higher than that of the air; usually between -12°C and -1°C. The high-pressure refrigeration vapour within the condenser is then cooled to the point where it becomes a liquid refrigerant once more, whilst retaining some heat. The liquid refrigerant then flows from the condenser in to the liquid line.
The Refrigeration Expansion Valve
Within the refrigeration system, the expansion valve is located at the end of the liquid line, before the evaporator. The
high-pressure liquid reaches the expansion valve, having come from the condenser. The valve then reduces the pressure
of the refrigerant as it passes through the orifice, which is located inside the valve. On reducing the pressure, the
temperature of the refrigerant also decreases to a level below the surrounding air. This low-pressure, low-temperature liquid is then pumped in to the evaporator.
The Refrigerant
The type of refrigerant used will depend on the pressure capabilities of the system and the temperatures that have to be
achieved during refrigeration. The following brief table shows the relationship between temperature and pressure, given
in bara, for two common refrigerants.
