Refrigerator Unit Model is part of the HSI trainingsystem for refrigeration and air conditioning technology. In combination withthe base unit HSI training system refrigeration and air conditioningtechnology, base unit the operational model of a domestic refrigerator iscreated. The model is plugged onto the base unit, secured using fasteners andconnected with refrigerant hoses to become a complete refrigeration circuit. Refrigerator Unit Model consists of arefrigeration chamber with a heater as cooling load, evaporator, fan andvarious expansion elements. The fan supports the achievement of an eventemperature distribution in the chamber. A cooling load can additionally besimulated with the heater. Solenoid valves enable the operation of the systemwith capillary tube or with expansion valve. All components are clearlyarranged on a panel. The operationof individual system components, here the temperature control, fan, heater,compressor and solenoid valves, takes place via the software. The softwareoffers the option to simulate faults. Temperaturesand pressures in the system are recorded by sensors and displayed dynamicallyin the software. The effect of parameter changes can be tracked online in thelog p-h diagram.