8. Illustration

Consider a vapour-compression refrigeration machine running on R142b (figure 5 ). The heat transfer fluid at the exchangers (condenser and evaporator) is air. The set parameters are cooling capacity (25 kW), air inlet/outlet temperatures at the heat exchangers (18/35 ˚C and 5/2 ˚C), evaporating temperature and superheat (-10 ˚C, 10 K), condensing temperature and subcooling (40 ˚C, 5 K) and discharge temperature at the compressor (60 ˚C). It is assumed that all components of this machine are well thermally insulated. Kinetic energy and potential energy in the fluid flow are neglected. The ambient temperature corresponds to the air temperature at the condenser inlet, i.e. 18 ˚C.