Study On The Influence Of Buffer Tank On Heating Performance Of Hot Water Type Air Source Heat Pump In Chill Region Rural House

Air source heat pump is a kind of heating equipment which uses air as heat source and drives the compressor through a small amount of electric energy to realize energy transfer,also has many advantages such as energy saving and high efficiency comparing with traditional heating equipment such as boiler.It is an important equipment for clean heating in rural areas of north China.In order to reduce the drop of water temperature in defrost period and ensure the stability of water temperature,the air source heat pump in the area is equipped with buffer tank.The air source heat pump equipped with buffer tank in northern China shows that the main existing disadvantages for heating include the attenuation of heating capacity and COP.In addition,the matching between the air source heat pump and the buffer tank and the problem of combining the buffer tank with different capacity under different heating load in different regions and different operating modes still need to be studied.This paper focuses on the physical running effect and performance improvement under different operating modes of air source heat pump equipped with buffer tank.Firstly,this paper investigates the heating demand and equipment usage of more than 100 households of typical rural area and background in northern China to find out the current usage of hot water type air source heat pump equipped with buffer tank and subjective feeling.De ST-h software is used to simulate the heat load of typical rural houses in heating season,and the heating demand,and research the indoor heating effect and summarizes the problems such as poor thermal comfort,low indoor temperature by the way of actual measurement.Secondly,the operation performance of 5HP and 3HP air source heat pumps without buffer tank and 100 L and 150 L buffer tank is measured in the performance testing laboratory.During the experiment,the laboratory ambient temperature and operation mode were changed,and monitor the inlet temperature,heat capacity,power consumption,COP and other parameters of the air source heat pump,and analyze the changes of performance parameters during the operation of the air source heat pump.The main conclusions are as follows:Compared with the direct supply,adding buffer tank,the heating capacity and operation performance of the air source heat pump is attenuated.In area A,the maximum attenuation of heat capacity of 5HP and 3HP with additional buffer tank is10.2% and 9.1% respectively,and the maximum attenuation of COP is 9.9% and 8.8%respectively.In area B,the maximum of heat capacity of 5HP and 3HP with additional buffer tank is 12.5% and 9.1% respectively,and the maximum attenuation of COP is12.5% and 8.8% respectively.The intermittent operation mode running only in the daytime has the highest heating capacity and COP,followed by the continuous operation mode,and the operation performance of the intermittent operation mode running only at night is the worst.For optimizing the start-stop time of intermittent operation,under the ambient temperature of-2℃,the 5HP equipped with 100 L and 150 L buffer tank should be opened 13 min and 19 min in advance,and can be closed no more than 60 min and 75 min in advance.The 3HP 100 L equipped with 100 L buffer tank should be opened 22 min in advance,and can be closed no more than 60 min in advance.Under the ambient temperature of 4℃,the time of opening in advance all can be shortened.For continuous operation and intermittent operation,direct supply mode has the highest HSPF in heating season.The HSPF of the 5HP air source heat pump with direct supply can reach 3.17 and 2.84 in area A and B,respectively.The 3HP can reach 3.15 and 2.72,respectively.Economic comparison: under continuous operation or intermittent operation mode,direct supply is the mode with the lowest NAC.After the buffer tank is added,NAC will be increase,and the larger the buffer tank capacity,the higher NAC.To sum up,inlet water temperature,heating capacity,power consumption and COP and other parameters will be affected by ambient temperature and tank capacity.In this paper,transforming the ambient temperature under different regions,different tank capacity to find out the law of the performance,as well as the start-stop strategy optimization for different mode,ensure the air source heat pump in high-efficiency operation,in clean heating policies in north China,provide theoretical support for different regions for the selection of the air source heat pump and the buffer tank and operating mode optimization.