Heat Transfer Analysis of Flat Plate Subjected to Multi-Jet Air Impingement using Principal Component Analysis and Computational Technique

The aim of this work is to investigate experimentally the variation in temperature, heat transfer coefficient and Nusselt number of a hot plate subjected to multi-jet air impingement cooling to use the multi-objective optimization technique to arrive at optimum conditions. A flat plate of ۱۵ cm x ۱۰ cm is heated through a heating foil with a constant heat flux of ۷۶۶۷ W/m۲. Air jets with and without swirling action are considered, fixing the distance of target surface from nozzle exit at ۲D, ۴D and ۶D. Reynolds numbers ۱۸۰۰۰, ۲۰۰۰۰and ۲۲۰۰۰ and pipe diameters ۸mm, ۱۰mm and ۱۲ mm have been considered for investigation. Experiments are designed and analyzed using Taguchi’s technique, coupled with principal component analysis for multi-variate optimization by calculating multi-response performance index (MRPI). Based on the observations made, it is concluded that lower H/D ratio and higher Reynolds number result in higher heat transfer coefficient, in accordance with the first principles. Heat transfer coefficient obtained for jets with swirl is compared with that of jet without swirling for the same Reynolds number and H/D ratio. Furthermore, it is concluded that introducing swirl results in increase of heat transfer coefficients for all the test conditions for ۱۰mm and ۱۲mm diameter jets. However for ۸mm jet, introduction of swirl reduced the heat transfer rate for all the test conditions. From Analysis of Variance (ANOVA), it is found that significant contributions on outputs are due to the effect of H/D ratio and Reynolds number. Confirmation experiments with optimum condition result in improved heat transfer coefficient and Nusselt number. Numerical simulation has also been performed with the optimum condition. It is observed that the simulation results are in consistence with the experimental results.

کلیدواژه ها:

Heat transfer ، Jet impingement cooling ، Swirl impingement jet cooling ، Principal component analysis