Conduction in composite slabs: Reliability of 1-D and 2-D calculations

•We model heat conduction in a composite slab using 1-D approach.•Comparisons have been made between results from 1-D and 2-D simulation.•Applicability of 1-D model is assessed for block with inserts of dissimilar materials.•Present approach can help in developing optimum shape of composite bricks.

In this paper, dimensional dependence of heat transfer is critically assessed for a solid slab having inserts of dissimilar material. The steady state two-dimensional analysis has been performed using the commercial software FLUENT 6.3 to get an idea about the feasibility of one-dimensional calculation for practical purpose. Comparisons are shown between 1-D and 2-D approaches to quantify the percentage error in calculations of heat transfer. The diamond shaped insertion is found to have the maximum deviation from the one-dimensional calculation due to the approximation taken during integration as the area under consideration is not perpendicular to the direction of heat flow. 1-D approach differs from the results of 2-D calculations as the thermal conductivity of the material inserted in the cavity deviates from the thermal conductivity of the original slab material and the same is the case as volume fraction of intrusion increases. Efforts have also been made to identify optimum shape and size of the inserts.