Experimental Comparisons on Heat Transfer Characteristics of CO2 Air Conditioning System with an Internal Heat Exchanger and without an Internal Heat Exchanger Using Minichannel Evaporator

摘要

This paper presented an experimental investigation on CO2air conditioning cycles using minichannel evaporator with an internal heat exchanger (cycle A) and without an internal heat exchanger (cycle B). The cycles were experimented under the ambient temperature around 31 °C. The pressure of system was adjusted by an expansion valve. The cooler pressure increases from 75 to 78 bar. The evaporator pressure decreases from 45 to 42 bar. The mass flow rate is around 113.4 kg/h. The results show that the temperature before expansion process of cycle A is lower than that obtained from the cycle B from 1 to 2 °C. Besides, the evaporator temperature of cycle A is lower than that obtained from the cycle B also. However, the COP of both cycles is approximately the same (COP 6.55).