回热器孔隙率对VM循环热泵性能的影响分析

Effect of regenerator porosity on performance of VM cycle heat pump

孔隙率是表征回热器结构和效率的重要参数,影响整个系统的流动和传热特性。以热驱动斯特林循环的VM(Vuilleumier,VM)循环热泵为研究对象,建立了其内部回热器的模型,研究了在不同的热源温度、系统压力、转速、容积比和工质的情况下,孔隙率对整个热泵系统性能的影响。结果表明:随着孔隙率的增加,系统性能系数先增加后减小,在0.6左右达到最佳。在相同孔隙率的情况下,系统性能系数随着热源温度、系统平均压力、容积比、转速的增加而分别增大,并且增加的幅度是越来越小的。对于工质而言,氦气和氢气的性能较优,而氮气的性能较差。综合考虑安全等因素,宜选氦气作为工质。

Porosity is an important parameter to characterize the structure and efficiency of regenerator,which affects the flow and heat transfer characteristics of the whole system.Taking VM(Vuilleumier)cycle heat pump as the research object,the model of its internal regenerator is established.The effects of porosity on the performance of the whole heat pump system under different heat source temperature,system pressure,rotating speed,volume ratio and fluids are studied.The results show that with the increase of porosity,the system performance coefficient first increases and then decreases,reaching the optimum at about 0.6.Under the same porosity,the system performance coefficient increases with the increase of heat source temperature,system average pressure,volume ratio and rotational speed,and the increase range is smaller and smaller.For working fluids,the performance of helium and hydrogen is better than that of nitrogen.Considering safety and other factors,helium should be chosen as working fluid.