The vapour compression cycle is the most common form of refrigeration, transferring heat from the area being cooled to a higher temperature region. Heat Pumps use this effect to recover heat at a useful temperature for heating or some other process by upgrading low grade ‘free’ heat e.g. from ambient air or water.
Due to concerns about the effects of global warming, awareness of energy conservation must increase and heat pumps are an effective method of reducing energy consumption. Hence an understanding of their operation is relevant to many engineering disciplines. The unit enables students to plot the pressure enthalpy and performance graphs as conditions are changed, so enhancing their understanding of the theory.
R134a refrigerant vapour is compressed in a hermetic compressor and then flows to a water-cooled condenser. Heat is transferred to cooling water and the refrigerant vapour is condensed to a high-pressure liquid which passes through a thermostatic expansion valve.
A switch allows the user to direct the flow of the expanding vapour to either an air or water source evaporator where heat is extracted, or the cycle is repeated. In order to recover waste heat from the compressor, the condenser cooling water also passes through a heat exchanger in the compressor casing. All components are mounted on a high-quality Aluminium panel and base.
Instrumentation includes pressure gauges, flowmeters, thermocouples and wattmeter allowing students to record all of the relevant parameters to create performance curves and refrigerant cycle diagrams.
