The comparison experiments under the given operating conditions were conducted to determine the performance difference of refrigeration systems with supply liquid refrigerant for the evaporator by gravity and direct expansion. Some system technical data were measured in the Psychometric Rooms

including refrigerating capacity

airflow volume and energy consumption. The results indicate that increasing the refrigerant flow rate can enhance the coefficient of heat transfer of the evaporator. The gravityflooded evaporator has much better heat transfer characteristics and efficiency without additional energy consumption under the low temperature condition. In addition

the resistance equilibrium to meet the liquid refrigerant recirculation was established

and the variation of the circulating rate under different conditions was analyzed.