Low charge transport refrigerator (II). Theoretical and experimental investigation

Considering the environmental challenges the refrigerant charge minimization is one of the most important targets for refrigerating and air conditioning applications. This paper presents a charge minimization study of transport refrigerator with eutectic plates. It was found that in traditional system significant charge increase in evaporator during the initial stage of pull-down was caused by interaction of thermostatic expansion valve and outlet pressure downstream regulator. For the baseline system (A) the charge increase was 1 kg, i.e. 25% of total charge. This charge increase may be minimized through implementation of different control systems. Other important factors are the volumes of receiver, heat exchangers and liquid line. Two low-charge refrigerators with different control systems were developed and tested. The charge decrease was 40-50% comparing to baseline systems.