Numerical Simulation,Optimization And Experimental Research Of The Air Side In Fin And Tube Heat Exchangers

Fin and tube heat exchanger has been widely used in chemical,refrigeration,energy and other industries.In the typical application of fin and tube heat exchanger,the air-side resistance comprises over 80%of the total thermal resistance.The flow field inside the heat exchanger is associated with maximum heat exchanger and minimum pressure drop.The optimization of the heat exchanger is focusing on enhancing the heat transfer while reducing the flow resistance.In this paper,several fin and tube with different shapes of air channels are studied.The flow inside the channels is analyzed by experiment and numerical simulation.The heat transfer enhancement inside the air channel is studied.The application of the elliptic tube is an effective alternative to the circular tube which can reduce the pressure drop significantly.In this study,numerical simulation and optimization of variable tube ellipticity?0.2-1?were studied at low Reynolds numbers?150-750?.The result of the numerical simulation showed that the reduction of the ellipticity of the tube can reduce the backflow area behind the tube,which reduced the flow resistance.However,the effect of the ellipticity on the Colburn factor is not significant.To obtain the optimal overall performance,neural network and genetic algorithm were introduced to optimize the configuration of the tube ellipticity.The Reynolds number?Re?,upstream tube ellipticity?e₁?and downstream ellipticity?e₂?are used as input,the Colburn factor?j?and friction factor?f?are set as output.Bayesian Regularization Neural Network?BRNN?was used to diminish the overfitting.The final trained neural network is then used to drive the Multi-objective Genetic algorithm to obtain the Pareto optimal solution.The optimal values of these parameters are finally presented.In this paper,three fin and flat tube heat exchangers are analyzed under the condition of dehumidification by numerical simulation and experiment.Three heat exchangers have different fin patterns.Heat exchanger 1?HX1?is a fin and flat tube heat exchanger with flat fins.Heat exchanger 2?HX2?is a fin and flat tube heat exchanger with louver fins.Heat exchanger 3?HX3?is a fin and flat tube heat exchanger with corrugated louver fins.The louver can guide the flow,which enhanced the heat transfer and the flow resistance.The experimental results showed that the heat transfer and pressure drop of HX2 and HX3 with louvers were significantly higher than that of HX1 at low Reynolds number.The heat transfer efficiency of HX2 with a larger proportion of louver size in the flow channel was increased by 5.7%¹8.3%compared to HX3.The pressure drop of HX2 was also 18.2%²9.3%higher compared to HX3.The numerical simulation showed the same trends.The louver diversion effect in HX3heat exchanger was weakened.For the effect of heat and mass transfer,the numerical simulation was in good agreement with the experiment.