Combined Radiation and Developing Laminar Free Convection Between Vertical Flat Plates With Asymmetric Heating

Abstract

A numerical investigation of the interaction of radiation with developing laminar free convective heat transfer in vertical parallel plate channels with asymmetric heating is presented. A unique iterative-marching technique is developed to solve the resulting nonlinear partial differential field equations and the integrodifferential radiation constraint equations. The introduction of radiation leads to five dimensionless parameters (heat flux ratio, Rayleigh number, aspect ratio, emissivity, and radiation number) which affect wall temperature and heat transfer performance. Radiation to the inlet-exit and the cooler opposing entrance wall significantly alters the nonradiation results by reducing the maximum wall temperature by as much as 50 percent. The nonradiation fully developed flow solution often could not be obtained with radiation present. Under certain conditions the Nusselt number actually becomes negative indicating a large radiative loss to the exit and a subsequent heating of the wall by the high local fluid temperature. The numerical results are verified experimentally.