An exact modelling for thermal diffusivities of solid objects exposed to heating

Abstract

A new simple model for determining the thermal diffusivities of solid geometrical objects (i.e., infinite slab, infinite cylinder, and sphere) being heated in a heating medium is proposed. In the unsteady-state heat transfer modelling, the lag factor and heating coefficient for heating applications were well-defined as being in a cooling process. In addition, new characteristic equations for the case of 0 < Bi < 100 in the transient heat transfer were developed instead of the existing complicated equations, and these were employed. In order to test the present model, the literature heat transfer data were used as an example and the use of the model was described in detail. The results of this study indicate that the heating coefficient has a direct influence on the thermal diffusivity and that the present model permits the determination of the thermal diffusivity values of solid geometrical objects in a simple and accurate manner.