非共沸混合工质自复叠热泵相积存实验研究

混合工质循环浓度是影响自复叠热泵循环性能的主要因素之一,而相积存导致工质循环浓度偏离充灌浓度,造成热泵性能变化.实验结果表明热泵中存在明显的相积存,最大可达充灌总量的50%以上;加热水温度对相积存的影响很大,每升高10℃,积存量减少10%～21%;工质充灌浓度一定时,积存量随充灌量的增大而增加,工质充灌量增加10%,其积存比例增加1%左右.相积存导致工质循环浓度高于充灌浓度1.6%～37%,由于工质积存量随加热水温度的升高不断降低,循环工质浓度受相积存的影响也不断减小而逐渐接近充灌浓度.

Experimental Study on Phase Holdup in Auto-cascade Heat Pump with Zeotropic Mixture

The circulating composition of a refrigerant mixture is one of the main factors that influence the COP of auto-cascade heat pumps. The phase holdup causes the different real circulating composition from the filling composition, leading to the change of the COP value. Our experimental results show that the phase holdup existed in the system obviously and the refrigerant holdup was up to 50% of the total charge. The refrigerant holdup decreased by 10%-21% of the total charge when the temperature of the water heated by the heat pump increased by 10℃. When the filling composition was constant, the proportion of the refrigerant holdup increased by about 1% as the refrigerant mixture charge increased by 10%. The phase holdup resulted in the real circulating composition 1.6%-37% greater than the filling composition. The refrigerant holdup decreased with the increase in the hot water temperature, and then the circulating composition would be close to the filling composition gradually.