IMPROVEMENT OF CLASSICAL LUMPED MODEL FOR TRANSIENT HEAT CONDUCTION IN SLAB USING HERMITE APROXIMATION

The present work aims at applying the ideas on the analysis of improved lumped - parameter model for transient heat conduction in a slab with temperature - dependent thermal conductivity. The transient temperature is found to depend on various model parameters , namely, Biot number, heat source parameter and time. Polynomial Approximation Method (PAM) has been possible to derive a unified relation for the transient thermal behavior of solid (slab and tube) with both internal generation and boundary heat flux. I n all the cases, a closed form solution is obtained between temperature, Biot number, heat source parameter and time. An improved lumped parameter model has been adopted through two point Hermite approximations for integrals. For linearly temperature - dep endent thermal conductivity, it is shown by comparison with numerical solution of the original distributed parameter model that the higher order lumped model (H1,1/H0,0 approximation) yields significant improvement of average temperature prediction over th e classical lumped model. A unified Biot number limit present analysis has been compared with earlier numerical and analytical results. A goo d agreement has been obtained between the present prediction and the available results.