Theoretical And Experimental Research On Cycling Performance Of High Temperature Electric Heat Pump Working Fluids

Nowadays,the contradiction between rapid economic development and environmental pollution and energy inefficient utilization is becoming more and more prominent in China.Industrial energy consumption accounts for 70%of the total energy consumption in society.At the same time,the low utilization rate of industrial waste heat leads to the limited utilization rate of energy in the system.If the waste heat resources are fully utilized,it will play a significant role in energy saving and emission reduction,so industrial waste heat recovery is one of the important directions of energy saving and emission reduction.Significantly different from conventional heat pump conditions,industrial waste heat utilization is characterized by "large temperature rise" and "high condensation"due to the lower industrial waste heat grade and higher temperatures required for hot links.Because the pure working fluid has poor comprehensive performance under this condition,the selection of non-azeotropic refrigerants for electric heat pump is discussed in this paper to meet the requirements of this working condition.The details are as follows:The thermodynamic theoretical cycle model of high temperature heat pump was built.Nine pure refrigerants with potential for mixing refrigerants of high temperature heat pump were selected for design calculation and analysis.Four high temperature refrigerants,R142b,R236ea,R236fa and R245fa,were selected.Among them,R245fa,R236ea and R236fa are considered to prepare mixed refrigerants because of their low heat production per unit volume.In the thermodynamic theoretical cycle model of high temperature heat pump,the components of seven mixed refrigerants for R245fa+R134a,R245fa+R152a,R245fa+R227ea,R236ea+R134a,R236ea+R152a,R236fa+R134a and R236fa+R152a were analyzed.When the inlet and outlet temperatures of waste heat low temperature water on evaporator side is 50/35 0C and the inlet and outlet temperatures of hot water on condenser side is 60/85?,the refrigerants had obvious excellent performance for R245fa+R134a.Potential,and mixing refrigerant R245fa+R134a(0.53/0.47)is a more suitable combination under this design condition,which is named HD-0.47 in this paper.The simulation calculations of the working fluids R142b,R245fa and HD-0.47 in the high-temperature heat pump thermodynamic theoretical cycle model show that the comprehensive cycle performance of HD-0.47 is the best when the inlet water temperature of the evaporator varies from 45? to 75?,and the parameters of HD-0.47,COP,unit volume calorific value and pressurization ratio,are obviously improved compared with R245fa.The comprehensive cycle performance of HD-0.47 is still better when the condenser inlet water temperature varies from 45? to 75?.A high temperature electric heat pump performance test bench was built to test the actual cycle performance of working fluids R134a,R142b and mixed working fluids HD-0.47.And high temperature hot water was successfully produced by using HD-0.47 as circulating working fluids to achieve the design export parameters.