CONJUGATE MIXED CONVECTION WITH SURFACE RADIATION AND SUBSTRATE CONDUCTION IN LAMINAR CHANNEL FLOW WITH DISCRETE FLUSH-MOUNTED HEAT SOURCES

摘要

Thermal analysis employing a full conjugation model is performed in this study for laminar airflow in a parallel-plate channel with discrete flush-mounted heat sources. The numerical model accounts for mixed convection, surface radiation, and two-dimensional conduction in the substrate. The effects of Reynolds number, surface emissivity of walls and heat sources, as well as thickness and thermal conductivity of the substrate, are analyzed in detail. It is shown that participation of radiation brings the wall temperatures closer, and the trend of temperature variation along the top wall is drastically altered. Such effects are pronounced for black enclosures and diminished for high Reynolds numbers. The influence of substrate conductivity and thickness is very similar in that a large value for both parameters would facilitate redistribution of heat and tend to yield a uniform temperature field in the substrate. For highly conductive or thick substrate, the 'hot spot' cools down and may move upstream to the penultimate source. Radiation loss to the ambient increases with substrate conductivity and thickness due to the elevated temperature near the inlet and outlet, yet the total heat transfer over the bottom surface by convection and radiation remains unaltered.