Influence Of Building Usage Patterns (Day /night/all-day) On Heating Performanceand Applicability In Different Climatic Regions Of Air Source Heat Pump

It is generally accepted in the industry that using heat pumps only during the day will be more energy efficient than using them continuously or only at night.This is because the outdoor air temperature is higher during the day than at night,and the operation of the air source heat pump during the day can obtain a higher heating coefficient.At the same time,it is noted that the actual use time of the building can be divided into situations such as daytime only,nighttime only,or 24-hour continuous use.Previous studies on the performance and regional applicability of air source heat pumps have seldom considered the impact of day and night usage,especially lack of scientific,rigorous and systematic quantitative analysis and research.This paper considers that the different usage patterns of the building directly affect the design heat load of the building itself,the designed installed capacity of the air source heat pump,the actual outdoor temperature and partial load rate of the heat pump,etc.,thus affecting its energy saving,economy and regional applicability.In order to study this problem scientifically and quantitatively,the author selected 6 cities including Harbin,Shenyang,Lanzhou,Beijing,Wuhan,and Changsha from the three climate zones of severe cold,cold,hot summer and cold winter as typical areas,and took a building as a typical building.,the building design heat load,the installed capacity of the air source heat pump,the partial load rate of the heat pump,the heating performance coefficient,and the system seasonal performance coefficient under different day and night usage modes are simulated and calculated.On this basis,the energy-saving,economical and regional applicability of the air source heat pump under different day and night usage modes are analyzed.The main conclusions of the paper are as follows:(1)In the six typical cities studied in this paper,when the type of air source heat pump is properly selected,the average COP of the heat pump is greater than 2.4 in any building usage mode;greater than 2.0.According to the current "Code for Design of Heating Ventilation and Air Conditioning for Civil Buildings",all of them belong to the applicable category of air source heat pumps.This conclusion can greatly expand the traditionally considered applicable area of air source heat pump to the north;(2)From the perspective of system energy saving,the six typical cities are more energy efficient by using ultra-low temperature air source heat pumps.The paper gives the difference percentage of energy consumption of low temperature and ultra-low temperature air source heat pumps in different cities and different building usage modes;(3)From an economical point of view,the applicability of air source heat pumps varies depending on the day and night usage patterns of the building and the coldness of the region.The overall rule is that the larger the proportion of daytime use,the warmer the area,and the more economical it is to use the low-temperature type.The paper gives the corresponding relationship table of urban and building usage patterns and their applicable heat pump types,and gives the corresponding economic difference percentage of low-temperature/ultra-low-temperature heat pumps.