Product number: R833

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 ABS 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.

Specifications and resources

Panel: High quality ABS.
Controls: Operating parameters may be varied by manual adjustment of the evaporator and condenser water control valves, and selecting the air or water source evaporator by panel mounted switch.
Gauges x 2: Evaporating and condensing pressures
Multi-point Digital Temperature Indicator: 9 type K thermocouples. Resolution 0.1K
Flowmeters x 3: For condenser cooling water and evaporator water flow rates and R134a flow rate.
Digital Wattmeter for compressor electrical energy.
Safety Features:
- Condenser high pressure switch and compressor thermal overload switch.
- Residual current circuit breaker
- Combined double pole main switch and overload cut out.
- All electrical components connected to common earth conductor.