Energy efficiency improvement of the refrigeration cycle using an internal heat exchanger

Jarosław Muller


A refrigeration cycle modified using an Internal Heat Exchanger is presented. For different refrigerants, the net effect of using an IHX is either positive or negative due to refrigerant properties and working conditions. Wet refrigerant vapor at the inlet of IHX improves the cycle in various aspects. The evaporator performance is much better when not superheating the vapor. A “pure” effect of subcooling the refrigerant liquid at the inlet of the expansion valve results in an increased specific heat of evaporation. For zeotropic mixtures, increased subcooling results in lowering the evaporating temperature without lowering the pressure in the evaporator. The EER value can be improved for some refrigerants and for specific working conditions. Theoretical and experimental evaluations of this concept are presented. Commonly used refrigerants were evaluated theoretically and tested in a 10 kW (cooling capacity) test rig. R22 and R407C were analyzed.

Słowa kluczowe: efficiency, refrigeration cycle, internal heat exchanger, refrigerant mixtures