Conjugate natural convection from a vertical heated slab

Abstract

Conjugate natural convection heat transfer from a vertical plate has been investigated analytically and experimentally. Assuming the existence of vertically averaged interfacial temperature between plate and fluid, it is shown that there is a unique nondimensional parameter to characterize the problem. The interfacial temperature is obtained as a root of 5th order polynomial for laminar natural convection, and it is presented as a function of the conjugate parameter. For turbulent convection it is also shown that the polynomial becomes 4th order. A simple expression for the average heat transfer is given as a function of conjugate parameter and the apparent Rayleigh number defined by an overall temperature difference. An experiment, using a water vessel with a heating plate on a side wall, was carried out in order to test a proposed theory for the heat transfer. Three different materials, copper, stainless steel and ceramics, were used as a conductive slab. The measured average heat transfer rates are in good agreement with the theory.