Development And Application Of Spray Cooling Technology For Air-cooled Heat Pump Unit

Air-cooled heat pump unit is one of the common air-conditioning systems.Its refrigerating coefficient of performance(COP)is slightly lower than that of water-cooled unit.If environment temperature is high,the power consumption will increase,the refrigerating capacity and the COP will decrease.In this paper,the performance of new and old air-cooled heat pumps unit of the same model was tested and compared in the enthalpy difference room.The cooling capacity and COP of the old unit were reduced due to the dust on the condenser fins.In order to improve the performance of unit,a water spray system is applied to the unit.The results show that water spray can reduce power consumption by 6.97%,increase refrigerating capacity by7.81%and increase COP by 16.06%at the environment temperature of 43℃.The unit performance is better at high temperature.In addition,in order to ensure the cooling effect of the air flow and heat transfer of air and fins,an appropriate distance should be maintained between the nozzles and the fin.Based on the actual process of spray cooling,DPM model was established to simulate the cooling process of three spray schemes.When the spray direction is opposite to the incoming air direction,the spray flow will strengthen the air disturbance and enhance the evaporation effect of droplet particles and the diffusion effect of water vapor and the distribution of temperature and humidity are more uniform..When the environment temperature from 303K to 321K,the average temperature drop increases from 2.33K to2.94K,the average humidity increases from 13.56%to 15.71%,the spray evaporation efficiency increases from 55.39%to 77.96%,the evaporation capacity increases from 0.853g/m~3 to 1.20g/m~3.The droplet distribution has a significant impact on the air temperature and humidity distribution.The droplet density and speed in the main spray area are large,which makes the air cool down and humidifying better in the main flow area.In addition,the environmental temperature has a great influence on the temperature drop of the air.The maximum temperature drop of the air increases with the increase of the environmental temperature.The relative humidity of air has a great influence on humidity increment.The maximum humidity increment of air decreases with the increase of relative humidity.Spray water temperature has little effect on temperature and humidity.