The Effect Of Different Angles On The Performance Of Finned Tube Evaporators In Different Types Of Computer Room Air Conditioners

With the rapid development of IT industry in the world, the high energy consumption of data center has become a problem that can not be ignored. As for the air conditioner of the engine room, the heat exchanger is a very important component of the heat exchange. The efficiency of the heat exchanger is directly related to the performance of the refrigeration system. Therefore, one of the effective ways to save energy is to strengthen the reasonable design and operation management of heat exchangers.This paper mainly uses the software FLUENT for different angles of positive and negative V type finned tube evaporator in room air conditioning for numerical simulation, obtained all kinds of cases (32.5 degrees, 39 degrees, 45.5 degrees)external space temperature field, velocity field and wind speed contour, pressure drop and heat, air side Nusselt number and air side, and from the face velocity uniformity was analyzed and the cause of the difference.In this paper, the enthalpy difference test bench is used to verify the simulation results. In addition, this paper also compares the characteristics of different volume and different relative humidity of the negative V type finned tube evaporator,compares three kinds of angle in the air flow as a percentage of the heat transfer performance of 100%, 90%, 80%, 70% and four operating conditions, and the influence of relative humidity on the heat transfer performance, including relative humidity respectively. Four class 45%, 50%, 55% and 60%.The refrigeration capacity and energy efficiency ratio under different operating conditions are compared and analyzed. The causes of this difference are analyzed from the aspects of evaporation temperature, suction and exhaust temperature, suction and exhaust pressure,condensing temperature, etc.. As far as the research is carried out, the following conclusions are obtained:(1) with the increase of the angle of the fin tube heat exchanger, the flow field in the space of the heat exchanger is more and more uniform, and the velocity stratification phenomenon of the heat transfer surface is also reduced, and the areas in the high temperature zone and the low temperature zone are decreased. Air side Nusselt number and pressure drop both showed an upward trend, and the Nusselt number under the positive V type is generally lower than the inverse V type, and the pressure drop is generally higher than the negative V type.(2) the face velocity distribution showed a similar trend of heat exchanger,located just below the vertical position of the fan wind speed is the largest, and as a center to decline gradually, in the heat exchanger reaches the minimum edge position.The negative V type evaporator has an angle of 32.5 degrees, 39 degrees and 45.5 degrees, and the corresponding non-uniformity of the face velocity is 0.86, 0.62 and 0.56 respectively.(3) as the percentage of air drops,the refrigerating capacity of the evaporator with three different angles will be reduced,while the energy efficiency ratio is on the rise. Regardless of how to change the volume percentage, angle of 39 degrees and 45.5 degrees, the cooling capacity and energy efficiency ratio is far higher than the 32.5 degree angle of the evaporator. The difference is more obvious when the air volume percentage is 80% and 70%. Compared with the highest refrigerating capacity,the cooling capacity is decreased by 5.7% and 6% respectively, and the energy efficiency ratio is decreased by 3.5% and 6.7% respectively. When the air volume percentage is 70%, the refrigerating capacity of the evaporator system with an angle of 45.5 degrees is increased by 3.4% compared with the evaporator with an angle of 39 degrees, and the energy efficiency ratio is increased by 3%.(4) as the relative humidity increases, the cooling capacity and energy efficiency ratio of the three angle evaporators increase as a whole. When the air volume percentage is 80%, the evaporator with an angle of 32.5 degrees increases when the relative humidity increases from 55% to 60%, and the refrigerating capacity and energy efficiency ratio are much higher than other kinds of conditions.In this paper,depending on different angles of positive and negative V type finned tube evaporator in room air conditioning for numerical simulation and experimental research, some conclusions obtained above. It has some practical value and academic significance, provide a theoretical basis for the design and optimization of evaporator in air conditioning room.