R125/R290混合工质热泵制冷剂变流量特性研究

Behavior of heat pump using R125/R290 with variable refrigerant flow rates

对混合工质R125/R290(25/75,质量配比)热泵变制冷剂流量特性进行了实验研究,并以55℃热汇出口温度为例,与被替代工质R134a和R22进行了对比分析。研究结果表明:随着制冷剂流量增大,排气温度线性下降,单位质量制热量则先上升后下降,系统COP随着制冷剂流量的增加表现为先线性增加后缓慢下降的趋势;在混合工质流量为1.12kg/min时,系统出现最大COP值3.040;系统火用效率则随着制冷剂质量流量的增大而增大。整个实验工况范围内,传热温差窄点一直保持在换热器中间部位。实验结果表明,在实验工况范围内,R125/R290(25/75)有望成为R134a及R22的替代工质。

Experimental study of heat pum refrigerant flow rates was carried out, and co p using R125/R290 （25/75 by mass） with variable mpared with that of R134a and R22 under the condition of 55℃ heat sink outlet temperature. The results indicate that, with refrigerant flow rate increasing, the discharge temperature linearly decreases, the heating capacity increases first and then decreases, and the coefficient of performance （COP） increases linearly and then decreases slightly when the refrigerant flow rate is 1.12 kg/min. A peak value of COP was obtained, and the exergy efficiency of the system increases with the refrigerant flow rate increasing. Meanwhile, the pinch point of heat transfer temperature always keeps in the middle of the heat exchanger. The results also show that, the new eco-friendly binary refrigerant is a promising substitute for R134a and R22 used in heat pumps, which are of significance for the application of heat pump using R125/R290 under variable conditions.