Study On Thermal Environment Around Air Source Heat Pump Unit Group

Under the current background of energy saving and emission reduction,air conditioning energy saving has become an important way of building energy saving.Air source heat pump is more and more widely used in China because of its advantages of high energy efficiency,convenient installation and flexible layout.In the actual engineering layout,in order to meet the needs of building load,air source heat pumps often need to be used together,but often due to site restrictions,unit group layout is difficult to meet the optimal requirements,and ultimately lead to poor air flow around the unit and reduce the unit efficiency,resulting in a certain amount of energy waste.Therefore,it is of great significance to study the influence of thermal environment around air source heat pump unit group.In this thesis,Flunet software is used to study and analyze the air source heat pump group and its surrounding thermal environment.The standard K-ε turbulence model is adopted to consider the density change caused by temperature difference,and the Boussinesq hypothesis is introduced.In this thesis,the distribution of temperature field of unit cluster under different arrangement modes,peripheral shielding and different unit spacing is simulated.At the same time,the influence degree of outdoor wind on single unit and the thermal environment around unit cluster is studied and analyzed.Firstly,by comparing the temperature field around the same type of units in the centralized and regular arrangement of 1×1～6×6 arrays,it is found that with the expansion of the unit array,the average air inlet temperature of the unit group decreases slowly,and the average air inlet temperature of the central unit decreases by 0.95 K.Taking an actual project as an example,it is found that when different types of units are running together,the unit with lower power has higher operation performance,and the average inlet air temperature of small unit is about 1.7K higher than that of large unit.Secondly,in view of the existence of peripheral shielding around the unit cluster,this thesis takes 5×5 array as an example to conduct simulation analysis on the unit cluster at different shielding distances.It is found that the average air inlet temperature of the unit cluster and the average air inlet temperature of the central unit increase by 0.34 K and 0.12 K when the shielding distance increases by 0.1m.Through the simulation of an actual project,it is found that the shielding of the wall has an obvious hindrance effect on the air flow around the unit,resulting in most of the wind from the unit stuck in the area near the unit group.At the same time,by comparing the unit inlet air temperature when the unit horizontal spacing is0.1m to 1m,it is concluded that the unit horizontal spacing should not be less than 0.3m in centralized layout,and it is recommended to be greater than 0.7m,and should be increased as much as possible when site conditions permit.In addition,in order to explore the influence of outdoor wind on unit group,this thesis first conducts simulation analysis on a single unit under different wind direction and speed,and finds that outdoor wind mainly affects the amount of back flow air in the leeward side of the unit,and then affects the unit as a whole.Taking 5×5 array unit cluster as an example,it is found that the lateral outdoor wind mainly affects the downwind unit of the unit cluster,and the temperature around the upwind unit is close to the ambient temperature.With the increase of outdoor wind speed,the low-temperature zone inside the unit group gradually shifts to the leeward side.With the increase of the outdoor wind speed,the low temperature zone in the unit group began to spread to the windward direction.