结霜工况下R410A热泵空调器动态特性的数值模拟

将选用R410A工质的热泵室外换热器表面的结霜视为准稳态过程,建立了热泵系统的分布参数模型,用有限差分法对其在结霜工况下的动态特性进行了数值计算。换热器采用分相流模型,并考虑了室外换热器表面结霜引起风量下降及换热器管排布置的影响,毛细管模型中考虑了"闪点延迟"和"壅塞流"现象。计算结果表明,在霜开始形成阶段,室外换热器表面结霜有助于改善空气源热泵性能,而在结霜循环的后期,霜层厚度快速增长,热泵的制热量、性能系数等迅速下降。

Numerical simulation on dynamic performance of air source heat pump with refrigerant R410a under frosting conditions

With regarding the frost accumulation on the outdoor coils as a quasi-steady process,a distributed parameter model was presented for a air source heat pump(ASHP) system with refrigerant R410A.The dynamic performances of the system under frosting conditions were simulated by using the finite difference method.In the models of the heat exchangers the split phase flow model was used,in the meantime,the decrease in the airflow rate due to frost accumulation on the outdoor coils and the tube row arrangement were considered.The under-pressure and shock flow of the refrigerant in the capillary tube were included.The simulation results indicate that the frost accumulation on the outdoor coils is benefit for the performance of the ASHP system.In the last period of the running time,the frost thickness grows rapidly,hence,the heating capacity and the COP of the ASHP system reduce rapidly.