中间补气高温热泵蒸汽系统热力学分析

Thermodynamic Analysis of High Temperature Heat Pump Vapor System with Intermediate Vapor Injection

为有效回收利用工业过程中产生的中低温余热,以中间补气高温热泵蒸汽系统为对象,建立热力学模型,选出了R123、R245fa与R1234ze(Z)三种典型高温热泵工质作为研究工质,考查了蒸发温度、冷凝温度、补气率与等熵效率等参数对系统性能的影响。研究结果表明,在采用不同循环工质的高温热泵蒸汽系统中,中间补气可以提高系统的COP,并降低压缩机的排气温度。对于目前主流的高温热泵工质R245fa,在蒸发温度为55℃、冷凝温度为125℃、补气率为0.5时,系统COP为3.4,较无补气时提升19.3%,排气温度降低1.2℃。

In order to effectively reuse the medium-low temperature waste heat generated in the industrial process,a high temperature heat pump vapor system with intermediate vapor injection is developed.A thermodynamic model is established,and three kinds of typical working fluids,i.e.,R123,R245fa and R1234ze(Z)are selected to conduct the study to evaluate the influence of evaporation temperature,condensation temperature,injection mass flow ratio and isentropic efficiency on the system performance.The results of research indicate that for the high temperature heat pump vapor system with different cycle fluids,the intermediate vapor injection technology can improve COP of the system and lower the discharge temperature of the compressor.For R245fa,the mainstream working fluid at present,when the evaporation temperature is 55℃,the condensation temperature is 125℃and injection mass flow ratio is 0.5,the COP of the system reaches 3.4,increasing 19.3%compared with that of the system without intermediate vapor injection,and the discharge temperature has dropped 1.2℃.