Analysis of thermal mixing via Bejan’s Heatline during natural convection within square cavities with discrete heat sources

Abstract

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.Natural convection is the governing phenomena in many engineering applications. The conventional method of differential heating of an enclosure may result in inadequate thermal mixing and poor temperature distribution leading to high amount of energy loss. In the present study, an alternative, energy-efficient method of distributed heating of the cavity is studied and compared with the differential heating case in enhancing the thermal mixing and improving the temperature distribution in the cavity. Six different cases, depending upon the location of the heat sources on the side walls of the cavity, are studied. Fluids with Pr = 7 have been investigated at high Rayleigh number (Ra = 103 − 105). Galerkin finite element method has been implemented for solving the governing equations and Poisson-type of equations for streamfunction and heat- function. Heatlines are found to be adequate tools for visualizing and understanding the heat energy distribution occurring inside a cavity. It is found that thermal management policy of distributed heating significantly influences the thermal mixing and temperature uniformity in the enclosures.