| In this paper,the turbulent flow and heat transfer performance of the flow passage between two plates are simulated and experimentally study.The numerical simulation is based on the k-? turbulence model,and the influence of water vapor diffusion is considered.The whole flow field is calculated according to the three-dimensional flow.In this paper,the different inlet air conditions and different pad structures are calculated and analyzed,the results are compared with the experimental results.At the same time,the optimization of the pad structure is analyzed and some suggestions are given.In this paper,the distribution of velocity field,temperature field,pressure field and relative humidity field is given in the 100 mm thick T5090 pad,when the inlet air dry bulb temperature is 35?,the moisture content is 0.0143kg/kg(a),and the inlet air velocity is 1.8 m/s.The distribution characteristics of different flow fields are analyzed,and the flow characteristics of the pad channel in the local micro region are obtained.The physical models of different pad structures are established,and the numerical simulation of different physical models are carried out by changing the inlet air velocity,the dry bulb temperature and the pad thickness.The influence factors of heat transfer and mass transfer under different conditions are analyzed.At the same time,the outlet temperature,evaporative cooling efficiency,pressure drop and so on are compared with the experimental data,and the accuracy of the model is verified.A comprehensive coefficient of performance is defined,that is,the ratio of the cooling capacity of the filler to the loss of the resistance is used as an index to evaluate the performance of the filler.The corrugated pad and triangular pad are modeled and calculated by numerical simulation.The results show that the efficiency of evaporative cooling is higher than that of triangle,and the comprehensive coefficient of performance is larger than that of triangle pad channel.It can be seen that the performance of corrugated pad channel is better than that of triangle.At the same time,the T5090 pad of 100 mm,75mm and 50 mm are compared.The results showed that with the increase of pad thickness,the evaporative cooling efficiency increased,but the comprehensive coefficient of performance decreased.It can be seen that only use the evaporative cooling efficiency to evaluate the advantages and disadvantages of the filler is not appropriate,the evaporation efficiency can only reflect the cooling capacity of the filler,but the pressure consumed by the filler can not be reflected.Therefore,in the selection of pad,we should not only focus on the evaporation capacity of the filler,but also pay attention to the pressure drop by the filler power consumption,with a comprehensive coefficient of performance to evaluate the advantages and disadvantages of the filler is more appropriate.The comprehensive coefficient of performance is used to optimize the pad from three aspects: wave height,corrugated length and corrugated inclination.The results show that when the wave length of T5090 pad is kept unchanged,the change of the height of the corrugation is 3.5mm,5mm,6.5mm,8mm in turn,and the comprehensive coefficient of performance reaches the maximum at 5mm.Also maintain the T7090 type pad wave height 7mm unchanged,change the corrugated length followed by 23 mm,25mm,27 mm,29mm,31 mm,comprehensive performance coefficient at 27 mm to reach the maximum.We change the inclination of the T7060 type pad in order of 30 °,35 °,45 °,55 °,and keep the other inclination unchange,the comprehensive performance coefficient is the largest when the two inclination angles are 30 °.These numerical simulations provide a reference for the optimal design of the actual pad. |
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