Experimental investigations of CO2 trans-critical refrigeration system with and without internal heat exchanger for warm climate.

In this article, performance of a CO2 trans-critical refrigeration system is experimentally investigated within temperature range 32°C to 45°C, with and without internal heat exchanger. The experiments are conducted for two different evaporator temperatures, 0°C and -5°C, in each, case for four different ambient temperatures 32°C, 35°C, 40°C and 45°C, for a range of gas cooler pressures. The investigation also covers effect of fan speed on cycle performance for air flow velocity ranging 1 to 3 m∙s-1 over the gas cooler. The experimental study brings out varying level of performance enhancement due to the internal heat exchanger. For the high ambient operation (45°C), the maximum enhancement observed for COP is 5.7% at -5°C evaporator temperature, while the same is found 5.01% at 0°C evaporator temperature, for suitable air flow velocity near 1 m∙s-1. A rise in compressor discharge temperature is also recorded when internal heat exchanger is used.