Research On The Heat Transfer Performance And Optimization Of The Air-supply Evaporator Under The Computer Room Air Conditioner

With the rapid development of emerging information industries such as"Big Data","5th generation wireless systems","Artificial Intelligence"and"Cloud Computing",the number of data rooms as their infrastructure has continued to increase,and the problem of high energy consumption in data rooms has become increasingly prominent,and energy conservation issues Received great attention.The current main cooling method of the data room in China is air-conditioning air supply cooling.Although this cooling method is simple in form and low in cost,it has high energy consumption.Among them,the insufficient heat exchange performance of the heat exchanger is an important reason for its high energy consumption..Therefore,it is of great engineering application value to study the heat exchange performance of the heat exchanger of the air conditioning unit in the computer room,and to optimize the air distribution and heat exchange effect of the air conditioner heat exchanger in the computer room.In this paper,for the V-shaped finned tube heat exchanger in the air-conditioning unit of the lower blower type room,firstly,the porous medium model and heat source model in the FLUENT software are used to analyze the existing V-shaped finned tube heat exchanger and the improved post-heat exchange.The temperature field and velocity field of the heater were numerically simulated,and the heat exchange effect of the existing and improved rear heat exchangers was compared and analyzed.Subsequently,the performance test of the V-type heat exchanger was carried out in the enthalpy difference laboratory.The flow and heat transfer characteristics of the heat exchanger under different working conditions were tested.The comprehensive numerical simulation and experimental test results were given to give the V-type heat exchanger.Optimized design scheme of heat exchanger.The main research contents and conclusions are as follows:(1)The porous medium and heat source model in FLUENT were used to simulate the airflow structure and temperature distribution in the V-type heat exchanger and the flow and heat transfer performance of the V-type heat exchanger at different angles were studied.The simulation results show that the following In the V-type heat exchanger of the air-supply unit,there is great unevenness in the distribution of wind speed.The wind speed in the middle area of the heat exchanger is higher and the heat exchange effect is the best.The wind speed on both sides of the heat exchanger is lower than that in the middle area.The greater the air volume,the stronger the unevenness of airflow.In addition,under the condition that the area of??the heat exchange area is unchanged,the increase of the angle of the heat exchange plate within the range of 24°?30°can effectively increase the uniformity of the wind speed distribution on the windward surface of the heat exchanger,there by effectively increasing the heat transfer performance.(2)The flow and heat transfer characteristics of the A/M-type heat exchangers with lower air supply are numerically simulated and compared with the V-type heat exchanger.The research results show that:Under the condition that the size of the frame and the heat exchange plate are unchanged,the temperature of the outlet section of the V-type heat exchanger and the A-shaped heat exchanger is similar.However,compared with the V-type evaporator,the area of the A-shaped heat exchanger that needs to be insulated is much smaller than the V-type heat exchanger,and it needs to cover about 1.85 m~2of insulation material area,which can save production costs to a certain extent.When there are multiple V-type heat exchangers,the M-type heat exchanger can increase the placement angle of one side heat exchange plate under the premise of the same frame,thereby effectively improving the unevenness of the distribution of the airflow organization,thereby enhancing the heat exchanger overall heat exchange effect.(3)The flow and heat transfer characteristics of the V-type heat exchanger under different working conditions were experimentally studied,and the flow and heat transfer characteristics of the heat exchanger under different working conditions were compared and analyzed.The characteristics of the heater were studied.The experimental results show that the wind speed distribution on the windward surface of the heat exchanger has great non-uniformity,which validates the results of the numerical simulation.In addition,after the filter is installed on the windward side of the heat exchanger,although the resistance has increased,the wind speed at each measurement point is reduced compared to the case without the filter,but the distribution of wind speed is more uniform and the overall heat exchange effect is better,the cooling capacity is increased by 2.4%,which shows to a certain extent that increasing the uniformity of the wind speed distribution can effectively improve the heat exchange effect of the heat exchanger.In addition,by measuring the outlet temperature of each refrigerant pipeline,it is found that the outlet temperature of each refrigerant pipeline is different,which affects the heat exchange effect of the entire evaporator.Therefore,when designing the pipeline of the heat exchanger,the temperature difference of each refrigerant pipe should be minimized.When the number of channels is unchanged,change the refrigerant flow distribution,short pipelines should be arranged in areas with good heat exchange effects,and the relatively long pipelines should be arranged in areas with poor heat exchange effects to ensure the superheat of the refrigerant at outlet meets the requirements of entering the compressor.