Study Of Technical Measures To Improve The Cold Island Effect Of An Array Of Air Source Heat Pump Units

With the implementation of the air pollution control action plan and the advancement of coal-to-electricity projects,air source heat pump systems have been widely used in district heating projects.Air source heat pumps use outdoor air as a low-temperature heat source.The low-level heat energy in the air is upgraded to high-level heat energy to be used.It is a highly efficient,energy-saving,environmentally friendly,and applicable heating technology.Modular air source heat pump units have the advantages of small size,flexible assembly,and simple installation.However,for regional heating projects,multiple modules are usually required for joint operation.The evaporator modules of the heat pump unit are often arranged outdoors in the form of an array.During the heating operation in winter,the low-temperature air discharged from the air source heat pump unit after heat exchange flows back into it.In the central area of the array,the air field temperature in the central area of the array is much lower than the ambient atmospheric temperature,forming a cold island effect in the unit array,so that the heat pump units in the central area of the array operate at a lower evaporation temperature,while the air source heat pump evaporator The heat exchange performance is greatly affected by the surrounding air field.The existence of the cold island effect greatly reduces the heating operation efficiency of the heat pump unit in winter,causing problems such as high operating costs and insufficient output of the heat pump unit.Proposing reasonable solutions and optimized operating strategies to improve the operating efficiency of the air source heat pump,reduce the operating energy consumption of the entire system,and optimize the operation of the system is of great significance.A heat source station in Shijiazhuang is heated in the cells of the air source heat pump and the electric boiler,and there is a serious cold island effect problem in the air source heat pump unit array during operation.This topic is based on the heat source station as the research object.The peripheral temperature field data of the heat source station air source heat pump unit array is collected by the experiment,and the method of simulating the heat pump unit array is simulated by using numerical calculations.The flow field distribution around the unit array at runtime array,analyzes the physical mechanism of the formation of the cold island effect and the impact of the operation of the thermal pump array.Based on this,technical measures have been proposed to improve the cold island effect,and compare the advantages and disadvantages of various measures,and propose the applicable conditions for measures.The research results show that the dense arrangement of the unit arrays cannot meet the heat exchange air volume required by the units in the central area,resulting in uneven pressure field distribution,causing the low-temperature air discharged from the heat pump units in the array to flow to the central area of the array and accumulate in the central area of the array,and The subsidence is accelerated under the suction action of the fan,and an obvious cold island effect is formed.After the heat pump unit array passes through the evaporator heat exchange tube bundle for heat exchange during operation,the low-temperature air discharged from the outlet of the unit returns for heat exchange again,which seriously affects the heat exchange characteristics of the unit operation.In actual operation,it often fails to meet the design supply.Heat increases the cost of operation and the instability of the output of the heat pump unit.This subject proposes three technical measures to improve the cold island effect of the air source heat pump unit by increasing the arrangement spacing of the units,installing baffle plates and installing baffle plates and raising the unit.It is effective to increase the arrangement spacing of heat pump units.It can alleviate the cold island effect formed during the operation of the unit in winter;the installation of baffles can significantly improve the uniformity of the evaporator inlet temperature during the operation of the heat pump unit array;on the contrary,the installation of the baffle makes the array The uniformity of the air suction volume of each heat pump fan in the heat pump is seriously reduced,which affects the heat absorption efficiency of the air source heat pump on the air side;the installation of baffles and the arrangement of the unit height can effectively eliminate the cold island effect in the operation of the unit,And the air duct at the bottom can ensure the entry of fresh air during the operation of the unit,which is the best solution for equipment installation,but the project cost is relatively high.