NATURAL-CONVECTION FROM 2-DIMENSIONAL DISCRETE HEAT-SOURCES IN A RECTANGULAR ENCLOSURE

Natural convection in a discretely heated enclosure is investigated experimentally and theoretically for single and multiple heater configurations. Mach-Zehnder interferometry is used to visualize the temperature field within the enclosure and to determine the local and average heat transfer characteristics of the discrete heat sources. The partial differential equations governing the conservation of mass, momentum and energy for the problem are solved numerically. The results show that for the single heat source configuration heater locations closer to the bottom of the enclosure yield the highest heat transfer in the high Grashof number range. However, the observation of previous work that the heat source location corresponding to maximum heat transfer is a function of Grashof number is confirmed. Discrete heat sources located near the enclosure bottom are also found to yield the highest heat transfer in the dual heater configuration. The heater placement for maximum heat transfer in both single and dual heater systems is explained in terms of the intensity of the buoyancy-driven flow in the enclosure. The thermal wake of the bottom heat source is seen to significantly affect the transport from heat sources above in the multiple heat source configurations. The lowest heat source, however, is influenced only marginally by the presence of a heater above.