Experimental Investigation of Natural Convection Heat Transfer from an Array of Protruding Heat Sources in A Square Enclosure

Heat transfer by convection with air as a medium is the most widely used technique for the cooling of electronic equipment and many other devices. An experimental study of natural convection heat transfer from multiple, protruding heat sources simulating electronic equipment is conducted. The heat sources are of square cross-section and protrude from the bottom wall of an adiabatic square enclosure. The aspect ratio of the enclosure is 3.5 and the 4×5 array of heat sources are arranged in an in-line manner. A heater with back insulation attached at the bottom of the heat sources supplies uniform heat flux and the applied heat flux varies from 200 to 1500 W/m². Air outlet opening areas and the heat fluxes are varied in this study. Steady state conditions are maintained throughout the experiment and the temperatures of heat sources are measured at fixed time intervals by thermocouples which are connected to a data acquisition system and a computer. The heat transfer coefficient, Nusselt number and Grashof number are obtained. Results indicate that the heat sources in the inner rows are hotter and the first row near the inlet is the coolest. Though the outlet area is less with ventilation ports, heat transfer is significantly higher. Heat transfer coefficient varies almost linearly with heat source surface temperature in all the cases. Grashof number, size and type of outlet opening areas strongly influence the Nusselt number.