Experimental Investigation of a Walk-in Refrigerator Performance using R290 as a Retrofit for R22

Abstract

An experimental performance study is performed on a refrigeration system equipped with a scroll compressor and tested with R22 using an electronic expansion valve (EEV) as an expansion device and controlled by proportional-integral-derivative (PID) control method. The system is tested at [Formula: see text]C, [Formula: see text]C, [Formula: see text]C, 0[Formula: see text]C and 4[Formula: see text]C evaporator air temperature and 20[Formula: see text]C, 25[Formula: see text]C and 30[Formula: see text]C condenser inlet water temperature at 50[Formula: see text]Hz compressor driving frequency and 50[Formula: see text]Hz evaporator fans driving frequency. R22 reached the set point at all temperatures except [Formula: see text]C evaporator temperature with 30[Formula: see text]C condenser temperature due to the severe increase in the compressor discharge temperature that could result in the lubricating oil burnout. Then, the system is retrofitted with a reciprocating compressor especially designed to be used with R290 and tested with R290 at the same evaporator and condenser temperatures using EEV as an expansion device. R290 reached all set points at all evaporator and condenser temperatures. Also, R290 was able to reach all evaporator temperatures at higher condenser temperatures, 35[Formula: see text]C and 40[Formula: see text]C, and this will be discussed in future work. The results show that using R290, the pulldown time decreases by 30.3–71.4%, the ON time ratio decreases by 1–23.6%, the compressor discharge temperature decreases by 46.6–81[Formula: see text]C, the refrigerant mass flow rate decreases by 28.8–50.4%, VRC decreases by 15.2–32.5%, the compressor power consumption decreases by 34.4–44.3% and coefficient of performance (COP) increases by 35–115.5%.