Optimization Of The Performance Of The Grille-type Louvered Heat Exchange

The parallel stream recuperator with its simple and lightweight configuration with high efficiency has been widely used in automobile air-conditioning systems.In this study,an important consideration is the structure that affects the performance of heat transfer in the recuperator with its louvered fins.In this article,the performance of the parallel stream exchanger with louvered vanes in an automotive air-conditioning is evaluated with numerical modelling as a main investigation methodology,and the performance is assessed with the heat transfer factor j,friction factor f and integrated factor Ejf as evaluation indexes to study the performance and flow characteristic of the air side of the louvered vanes.The major research in this article is presented below:(1)The modelling for conventional shutter fins was done and the mesh independency was verified using simulation software to produce simulation results.The simulations of the model have been compared against the three experimental associated patterns for verification purposes.These results demonstrate the accuracy demands required when the grid mesh dimension meets 0.07 mm.The simulations for the combined factorials have the maximum tolerances of 8.69%,4.04% and 3.38% against the Chang-Wang,Davenport and Dong Junqi associated formulations correspondingly;they satisfy the permitted technical uncertainties of the model which proves that the model developed can be reliable.(2)We propose the same boundary requirements for conventional shutter and conduct the simulations over the Reynolds range of 160 to 434 and compared with the results of the simulations for the conventional shutter.Their results demonstrate the heat conductivity element j is improved by 4.23% to 8.91%,while the friction coefficient f is lowered by1.28% to 4.16% and the combination of coefficient Ejf is improved by 6.72% to 11.68%when compared to that of conventional louvre fins.A comprehensive analysis shows that the combined heat transfer performance of the spacer louvre fins is better than that of conventional louvre fins.(3)The structural parameters of the grille louvre fins are optimised in terms of the number of grilles n,louvre angle θ,louvre spacing Lp and fin thickness δ.The heat transfer performance and flow properties of the grille louvre fins are investigated under the conditions of changing a single structural parameter.Numerical simulations were carried out under five operating conditions with inlet air velocities ranging from 1.52m/s to 4.12m/s.The results show that the best heat transfer performance is achieved with the number of grilles n=4,louvre angle θ=25°,louvre spacing Lp=1.7mm and fin thickness δ=0.11 mm.