For gravity feeding refrigeration system

when the hydraulic head was greater than the resistance to the evaporator

liquid refrigerant can recycle in loop formed by the evaporator and vapor-liquid separator. The strength of recycling was expressed by circulating rate

which was connected with hydraulic head and evaporation temperature. Resistance formulas to a small system were derived and a special recycling evaporator was designed. Resistance balance calculation in homogeneous flow model was completed. Then the effect of hydraulic head and evaporation temperature on the circulating rate of refrigeration system was experimentally investigated using the air-side heat balance method. The results showed the precision can be satisfied with the engineering demand. Cycling rate decreases as evaporation temperature increases

and the lower the evaporation temperature is

the smaller the change of cycling rate. Cycling rate increases as hydraulic head increases

and the augment formed by one unit hydraulic head increases with the decrease of hydraulic head. The changing rate decreases with the increase of evaporation temperature and there exists optimal cycling rate which is recommended as 4~5.