Simulation Study On Heat Transfer Performance And Evaporation Characteristics Of Evaporative Cooling Device

With the development of refrigeration technology,traditional refrigeration technology faces two main problems: energy problems and environmental problems.Evaporative cooling is widely used because of its wide source of cold source,simple installation and energy saving.Evaporative cooling air conditioning technology uses the principle that liquid water evaporates with dry air to reduce the temperature to obtain cooling capacity,that is,water and dry air can be exchanged for heat and moisture to obtain cold air and cold water at lower temperatures.When the partial pressure of water vapor of dry air is in an unsaturated state,it has the ability to do external work.As long as there is a water source,the dry air energy will be converted into heat energy.Evaporative refrigeration technology has many advantages such as energy saving,environmental protection,high efficiency,and good air quality.It is a truly sustainable refrigeration technology.It has been promoted to a certain extent in western China.Evaporative refrigeration air-conditioning technology can be divided into two categories: direct evaporative cooling and indirect evaporative cooling according to its refrigeration process.In Direct Evaporative Cooling(DEC),the air to be treated is in direct contact with the spray water in the spray chamber.The dry air meets the water to evaporate and cool to low-temperature humid air.The humidity increases at the same time.This paper conducts CFD simulations on two evaporative cooling devices,and discusses the effects of primary air inlet temperature and spray water temperature on the efficiency of the evaporative cooling device.By simulating the temperature distribution at the next secondary air outlet with different parameters,the water evaporation phase distribution,and the temperature distribution of the entire channel of the device,the rules affecting the heat transfer performance of the two evaporative cooling devices were obtained.At the same time,comparing the heat exchange performance of two evaporative cooling devices,a judgment method for selecting evaporative cooling is given.For the tube evaporative cooling device,a device with a tube diameter of 5 mm and 10 mm and a tube spacing of 5 mm and 10 mm was selected for simulation.For the plate evaporative cooling,the length of the plate is 500 mm and 1000 mm,and the width of the plate is 6 mm,8 mm and 10 mm.The effect of device size on evaporative cooling efficiency is obtained through simulation.After that,the heat and mass transfer process inside and outside the heat exchange pipe and the specific process of air and spray water flow were analyzed in detail.According to the simulation,it is found that both devices have a slow cooling of the primary air,and the secondary air directly contacts the water to cool down,and the temperature will quickly drop to the dew point temperature of the secondary air.For the tube evaporative cooler,the spray water will form a water film on the tube wall,increasing the contact area of the spray water and the tube wall,so the average temperature at the outlet of the primary air will be much lower than that of the plate evaporative cooler.Export.Indoor use in summer can lower the room temperature to a comfortable range,which is more suitable for the indoor environment.At the same time,the comparison found that the plate evaporative cooling device is more suitable for higher temperature environments,so the plate evaporative cooling device is more suitable for connecting to high-temperature places such as large machine rooms and handling large volumes of hot air.According to the fact that the cooling efficiency of the evaporative cooling device reaches 60% or more,it proves that the cooling efficiency of the evaporative cooling device is superior to the traditional refrigeration machinery.