A high efficiency refrigerator was developed to minimise energy consumption with a non-ozone depleting CFC-free refrigerant. The study was conducted on two 19.9 ft³ (internal volume) top mounted refrigerator/freezers with rotary compressor and energy saving valves. One of the two refrigerant/freezers was manufactured with significantly better insulation by increasing the wall thickness by 1.3 to 1.8 inches, thus enlarging the outside dimension. A comparison of the power consumption of the two units revealed 26% lower energy consumption for the better insulated unit. The unit with thick insulation was then equipped with a high-efficiency reciprocating compressor and modified to achieve a Lorenz-Meutzner refrigeration cycle. The refrigerator was charged with a CFC-free zeotropic mixture. An improved door seal was implemented. The results indicated that daily energy consumption decreased by up to 25% when comparing the single evaporator unit with one that included all the energy saving features. Comparing the best test results of the high-efficiency system with the best results of the standard insulated refrigerator/freezer, a decrease from 1.86 kWh/day to 1.008 kWh/day was observed. The cycling losses of the rotary compressor system are found to be lower than those of the system with the reciprocating compressor when both systems are using an energy-saving valve.

KEYWORDS: refrigerators, performance, thermal insulation, refrigerants, testing, comparing, energy conservation.