CONDUCTION, CONVECTION, AND RADIATION IN A CLOSED CAVITY WITH A LOCAL RADIANT HEATER

摘要

This study deals with the numerical investigation of combined heat transfer via conduction, laminar natural convection, and surface radiation in a closed rectagular cavity with a radiant heating source. Unsteady two-dimensional equations of mass, momentum, and energy conservation for complex heat transfer process under study were formulated in terms of the vorticity – stream function – temperature variables and solved by means of the finite difference method on a uniform grid. Developed numerical code was validated against two benchmark problems of convective and convective-radiative heat transfer. When analyzing complex heat transfer regularities, we varied the following parameters: dimensionless time 5t800, Rayleigh number 6*10^4Ra4*10^6, conduction-radiation number 19.71Nr78.84, surface emissivity 0.2e0.9, emitter length 0.1D1, walls thickness 0.05M0.25. According to the results of mathematical modelling, it was found that the radiant parameters significantly affected the formation of differential and integral characteristics of conjugate heat transfer. Along with that the convective Nusselt number was slightly changed in geometrical and physical conditions under study. An increase in the walls thickness led to a reduce in the temperature of the air cavity. However, the effect of wall thickness on the convective and radiative Nusselt numbers was not significant.