Experimental Study On Performance Of Direct Heat Pump Water Heater Based On Condenser Optimization

Under the background that energy shortage and environmental problems are increasingly affecting people’s life in China,using clean energy and improving energy utilization efficiency are one of the important measures for energy saving and emission reduction.At present,domestic hot water energy consumption has become the main contributor of building energy consumption in China,and it is still growing rapidly along with the development of economy and society and the urbanization process in China.It is an important means to reduce the energy consumption of domestic hot water and building energy consumption to produce domestic hot water by using high-efficiency and energy-saving hot pump water heater.Energy efficiency improvement and material substitution of heat pump system are hot research topics in the field of heat pump and important means to achieve carbon peak and carbon neutralization.Therefore,this paper studies the off-design performance of heat pump water heater(CCHP)with combined condenser and heat pump water heater(ICHP)with integrated condenser both theoretically and experimentally,in order to verify the feasibility of using combined condenser in direct heat pump water heater.The main work and conclusions of this paper are as follows:(1)In order to solve the problem of low heat exchange coefficient in the supercooled section of the integrated condenser,the zoning design calculations of the combined condenser and the integrated condenser for the direct heat pump water heater were carried out based on the condenser design model.The results show that the heat exchange in super-cooled section of condenser can be optimized by exchanging heat sink and refrigerant flow passage in condenser II,and the heat exchange area of combined condenser is only 83.33% of that of integrated condenser.Construct the experimental device of mixed refrigerant direct heat pump water heater,select the equipment and compare the performance of heat pump water heater(CCHP)with combined condenser and heat pump water heater(ICHP)with integrated condenser under variable conditions through experimental research and comparison.The purpose is to verify the feasibility of using combined。(2)With the experimental device of mixed working medium direct heat pump water heater,the performance of heat pump water heater(CCHP)with combined condenser and heat pump water heater(ICHP)with integrated condenser under variable operating conditions are studied and compared experimentally.The experimental results show that CCHP system obtains slightly higher COP and exhaust temperature than ICHP system under variable outlet and variable inlet temperature conditions.Heat generation and exhaust pressure are basically the same as those of ICHP system,so the combined condenser has obvious potential to replace the integrated condenser in the direct heat pump water heater.Under the same operating conditions,the COP of CCHP system and ICHP system has similar change trend,while under different operating conditions,the COP of the same heat pump system has very different change trend.(3)The theoretical model calculation results are compared with the experimental data.The results show that when the outlet temperature of heat sink is changed,the theoretical calculation results have the same trend as the experimental data.When changing the inlet temperature of heat sink,the experimental results are slightly different from some physical parameters of theoretical calculation results.The experimental COP and heat production show a trend of increasing first and then decreasing.The theoretical COP and heat production show a downward trend,while other parameters have the same change curve.