Investigation of the effect of cavity insertion in brick on heat transfer through using computational fluid dynamic simulation

In this study, heat loss through light weight concrete bricks as a function of the size and number of bricks’ cavities was examined via numerical simulation. To minimize the simplifications, conjugate convection and radiation heat transfer within the brick’s cavities filled with air was considered. Also, in the solid of the brick, conduction heat transfer was taken into account. To assess the orientation of the cavities in the brick, two geometrical constrains were employed in the design of the bricks leading to 22 different layouts for which there should be at least two cavities and at most nine enclosures inside a brick. Computational fluid dynamic approaches based on finite volume method were used for the simulations. 3D natural heat transfer with incompressible laminar flow was assumed in the cavities under steady state conditions. To analyze and compare the results in terms of thermal characteristics, the equivalent coefficient of conduction heat transfer was defined. Also, the results were presented with isotherms and velocity contours. Finally, the best configurations of air cavities in the view point of heat transfer were found. The results demonstrate that the configuration and size of the cavities have profound impact on the rate of heat transfer. Also, considering radiation heat transfer in the cavities is rather important.