Conjugate Forced Convection from Heat Sources on Substrates of Different Thermal Conductivity

This paper presents experimental and numerical results of conjugate forced-convection air cooling of discrete square heat sources under various operating conditions of air. Experiments have been performed for flowing air velocities of 0.6-1.4m/s circulated through a horizontal channel. The bottom surface of the channel was equipped with 3x5 aluminum heat sources mounted on FR4, Bakelite, and single-layer copper-clad boards subjected to uniform heat flux values of 1000, 2000, and 3000W/m2. From the experimental measurements, the surface temperature distribution of the square heat sources was obtained and the effects of the Reynolds number on these temperatures were investigated. Steady, incompressible three-dimensional conjugate forced convection from heat sources using FR4, Bakelite, and single- and multilayer copper-clad boards has been studied numerically using finite-element-based software to calculate the required cooling rate. The effects of substrate board thermal conductivity on heat transfer characteristics and fluid flow are investigated. The obtained experimental results indicate a deviation of under 5% with simulations. It is found that the surface temperatures of heat sources decrease with a increasing thermal conductivity and Reynolds number. The results of the temperature were correlated with the thermal conductivity, heat flux, Reynolds number, and Nusselt number.