Numerical investigation of the effective heat transfer coefficient for red clay hollow bricks

This study presents a numerical investigation of the effective heat transfer coefficient in red clay hollow bricks, accounting for the combined effects of heat diffusion in the solid clay and natural convection and thermal radiation within the air-filled cavities. Heat conduction through the solid material is modelled analytically, while the convective transport in the cavities is solved using the Fast Boundary-Domain Integral Method. To enhance computational efficiency, the H 2 -approximation is employed to reduce the cost associated with the boundary-domain integral formulation. A parametric analysis is carried out for bricks with varying numbers of cavities and under different temperature boundary conditions, enabling a systematic evaluation of their influence on the overall thermal performance. The results provide new insights into the interplay between cavity geometry, boundary conditions, and effective heat transfer mechanisms, offering guidance for the design and optimization of energy-efficient building materials.