Study On Heat Transfer Performance Of Plate In Counter-flow Plate Dew Point Indirect Evaporative Cooler

In the face of resource exhaustion and other issues,the development of energy-saving and environment-friendly air-conditioning system has become one of the development trends.Evaporative cooling air-conditioning technology utilizes the dry air energy to obtain cooling capacity,which is an energy-saving,efficient and economical cooling method.Firstly,the baffle spacing of counter-flow dew point indirect evaporative cooler is studied.Secondly,according to the heat and mass transfer characteristics,the influence of heat transfer surface combination on cooling performance is studied.Then,a new structure is proposed and its performance is investigated.Finally,the baffle evaporative cooling air-conditioning is studied experimentally.The main conclusions are as follows:(1)when the inlet velocity is less than 2 m/s,the baffle spacing increases with the increase of inlet velocity when the cooling efficiency of plate dew point evaporative cooler reaches the optimum.In the scope of the study,with the increase of channel length,the baffle spacing remains unchanged when the cooling efficiency reaches the optimum,which is 8 mm.when the channel length is 500 mm,the cooling efficiency first increases and then decreases with the increase of baffle spacing,and decreases significantly when the baffle spacing is greater than 11 mm.Under the same environmental conditions,the cooling efficiency increases with the increase of channel length.when the cooler adopts different plate structures,the partition spacing is different when the cooling efficiency reaches the optimum.(2)When the four surfaces(A,B,C,D)involved in heat transfer in the productair channel and the workair wet channel adopt the same sawtooth structure size respectively,the cooling effect of each surface is different and the cooling effect of C surface is the best.The outlet temperatures of four coolers,model 1(AC),model 2(BD),model 3(AD)and model 4(BC),all increase with the increase of relative humidity of air,ambient temperature and inlet velocity,and model 1(AC surface combination mode)has the best cooling effect.(3)A new type of counter-flow dew-point evaporative cooler with arc-ribbed plate structure is proposed.Compared with the traditional structure,the wet-bulb efficiency of the new type cooler is increased by 10.32%,25.82% and 13.87% under the conditions of inlet temperature,ambient humidity and inlet velocity,respectively.When the inlet velocity ratio of working air to product air is 1.5,the wet-bulb efficiency of the new type cooler is the highest,which is 126.24%.The efficiency decreases with the increase of circulating temperature of cooling water,and reaches the maximum when the spacing and the chord length of arc ribs are 5 mm and 15 mm respectively.(4)The experimental platform of plate counter-flow dew point indirect evaporative cooler test is established,and the effects of environmental conditions,inlet velocity and cooling water temperature on the outlet temperature of the product air channel were studied.The results show that the outlet temperature increases with the increase of environmental conditions,inlet velocity and cooling water temperature.