Study On Flow And Heat Transfer Characteristics And Structural Optimization Of Corrugated Sandwich Panel

There are various structural forms of heat transfer elements in rotary air preheaters,among which the corrugated type is the most common plate structure.The corrugated sandwich panel is composed of a positioning plate and a corrugated plate,bearing an important role in heat exchange.The flow and heat transfer property plays a decisive role in the working efficiency of a rotary air preheater.In order to find a plate structure with high efficiency and low resistance,numerical simulation and multi-objective genetic algorithm are used to investigate the flow and heat transfer property and structural parameter optimization of corrugated sandwich panels.This study provides a theoretical basis for the optimal design of the heat transfer elements of the rotary air preheater.The three-dimensional fluid models have been established based on four types of plate structures: L-type,YRD type,YR2 type,and DN type.The flow field,pressure field,temperature field distribution,and different flow trajectories of the air in each plate type channel were simulated using Fluent fluid simulation software.The variation laws of field synergy angle,Darcy friction factor,Nusselt number,and comprehensive heat transfer factor with Reynolds number and structural parameters were statistically obtained through post processing software.After comparison with experimental results,it was found that the error was between 1.78% and 6.59%.The reliability of the numerical simulation results is verified.The influence of a single factor on the flow and heat transfer property of the corrugated sandwich panel was studied by using the controlled variable method,and selecting four structural parameters of the YR2 type,namely,the corrugation inclination angle φ,the ripple height to width ratio ε,dimensionless s/d,and the ripple fillet r.The results showed that: The Darcy friction factor increases with the increase of φ and ε,and the Nusselt number reaches the maximum at φ=60° and ε=0.23,respectively;With the increase of s/d,both the Darcy friction factor and the Nusselt number decrease;With the increase of r,the Darcy friction factor gradually decreases,and Nusselt number reach the maximum When r=2.5mm.The results of two comprehensive property evaluation methods are analyzed,and the selection of corrugated sandwich panels in practical applications is determined.Based on DOE experimental design,a response surface model was constructed to explore the impact of interaction between different structural parameters.Taking the minimization of the Darcy friction factor and the maximization of the Nusselt number as the optimization objectives,the optimal combination of parameters sought in the global space by using a multi-objective genetic algorithm is φ=21.45°,a=4.42 mm,b=1.96 mm,s/d=3.06,r=1.45 mm.Compared with the initial structure,it was found that the Nu increased by 6.53% and the f decreased by 44.52%.