直热式空气源变频热泵热水系统的特性分析

摘要

模拟分析了一种直热空气源变频热泵热水系统，包括水箱模块与热泵模块的理论耦合特性和热泵系统在变工况下的运行特性，并且比较了压缩机频率每变化1 Hz 和冷凝温度每变化1℃对系统的影响。模拟分析表明：压缩机功率随环境温度变化的趋势为抛物线状，在20℃左右达到最高；制热量与环境温度呈正线性相关；热泵模块出热水流量随环境温度变化呈指数增长；当压缩机有效容积和吸气系数等参数不变时，制冷剂质量流量与环境温度呈正线性变化；制热 COP 随环境温度呈指数增长，随出水温度的升高而降低；调节频率可以更有效改善系统制热量，而降低冷凝温度从而适当降低用水温度（如42℃），可以更有效地降低功耗、增加出水流量。%The characteristics of a hot water unit with direct-heated and frequency-variable air source heat pump were analyzed,including the theoretical coupled characteristics of water tank module and heat pump module,the operation characteristics of the heat pump units in variable environment conditions and the comparative influences of compressor frequency and condensation temperature.The results show that the compressor input power changes along with the ambient temperature in a parabolic curve,and reaches the highest at 20 ℃.Besides,the heat capacity is of linearly positive correlation with the ambient temperature and the outlet water flow has exponential relation to the ambient temperature.Moreover, when the effective volume coefficient and suction coefficient of the compressor keep constant,the refrigerant mass flow rate has linear and positive relationship with the ambient temperature.In addition, the heat COP is of exponential relation to the ambient temperature,and decreases with the outlet water temperature.It is concluded as well that the adjustment of compressor frequency can change heat capacity remarkably,and the decrease of condensing temperature can decrease the outlet water temperature(such as 42 ℃)in a certain degree,thus decreases the compressor input power and increases the outlet water flow.