采用不同工质的高温复合热泵开水器特性研究

热泵开水器具有较高的能源利用效率,是公共场所电加热开水装置的理想替代品。从提高能源效率和一机两用的角度,构建了一种高温复合热泵开水器系统。建立了系统热力学模型,选R236fa、R245fa、R365mfc、R245ca、RC318和R236ea等6种较高临界温度的制冷工质,通过能量分析和火用]分析的方法,探讨了不同制冷工质对高温复合热泵开水器系统性能的影响。研究结果表明:R245fa作为工质的高温复合热泵开水器系统具有最佳的性能,而以RC318作为工质的系统性能最差。在给定工况下,R245fa作为工质系统制热性能系数(COP_h)为2.47,而其制冷性能系数(COP_c)为3.37,火用]损失和火用]效率分别为9.47 kW和49.07%;与R245fa相比,RC318作为工质系统的总能耗增加了39.53%。

Study on Characteristics of High-temperature Hybrid Heat Pump System for Boiling Water Heater with Different Refrigerants

The heat pump boiling water heater has been a candidate for the electric boiling water heater in public places because of its high energy efficiency.For efficiency improvement of the energy utilization and,a high-temperature hybrid heat pump system used as the boiling water heater was proposed for boiling/chilled drinking water production.The thermodynamic model of the novel system was established,and high critical temperature refrigerants,such as R236 fa,R245 fa,R365 mfc,R245 ca,RC318 and R236 ea,were selected to evaluate the influences of the refrigerants on the system performance in terms of energy and exergy analysis.The results indicate that the high-temperature hybrid heat pump system using R245 fa as working fluid has the highest energy efficiency,while the system with RC318 has the lowerest energy efficiency.Under the given operating conditions,the coefficient of performance at the heating mode(C OP_h)was 2.47,and the C OP at the cooling mode(C OP_c)was 3.37.The system exergy destruction and exergetic efficiency were 9.47 kW and 49.07%,respectively.Compared with the R245 fa,the system energy consumption of the RC318 as working fluid is increased by 39.53%.