Thermal performance of clay bricks with different fillings: a CFD analysis

Abstract

The thermal conductivity of 15 loadbearing and infill bricks was calculated through a Computational Fluid Dynamic (CFD) analysis. Clay bricks filled with air, expanded polystyrene EPS, and graphitized expanded polystyrene were selected from the catalogue of the manufacturer F.B.M. - Fornaci Briziarelli Marsciano. The company provided the geometric features of each block and the thermal characteristics of the clay mix and the filling. The thermal conductivity value of each air cavity was calculated in compliance with UNI EN ISO 6946. Each volume was discretized in triangular meshes. The equivalent thermal conductivity of each block was calculated starting from the simulation of the isotherms trend inside the sample and from the heat flux passing through it. The obtained results were discussed depending on the filling, the geometry, and the hole percentage. In general, thermal conductivity increases with hole percentage in the bricks with air. Similar geometries have similar thermal behaviour. EPS or graphitized EPS involve better thermal performance as the hole percentage increases. Finally, the influence of the different orientations of the blocks was investigated. Equivalent thermal conductivity values increase for horizontally-brick placed, especially in homogeneous and compact geometries.