Coupled Conductive-Convective-Radiative Heat Transfer in Hollow Blocks with Two Air Cells in the Vertical Direction Subjected to an Incident Solar Flux

Abstract

This work presents the results of a set of steady-state numerical simulations about heat transfer in hollow blocks in the presence of coupled natural convection, conduction and radiation. Blocks with two air cells deep in the vertical direction and three identical cavities in the horizontal direction are considered (typically used for building ceilings). Moreover, their outside horizontal surface is subjected to an incident solar flux and outdoor environment temperature while the inside surface is exposed to typical indoor environment conditions. The flows are considered laminar and two-dimensional over the whole range of parameters examined. The conservation equations are solved by means of a finite difference method based on the control volumes approach, relying on the SIMPLE algorithm for what concerns the coupling of pressure and velocity. The effects of the number of cells in the horizontal direction and the thermal conductivity on the heat transfer through the alveolar structure have been investigated. The results show that the number of holes has a significant impact on the value of the overall heat flux through the considered structure.