Internal baffles to reduce the natural convection in the voids of hollow blocks

Hollow bricks are widely used to build facades of light weight and high thermal resistance. The air filled voids within the brick configuration elevates the block’s thermal resistance. Disturbing the natural flow patterns developed inside the voids affects the blocks overall thermal resistance. This paper presents a numerical study for a section of a masonry brick represented by a baffled squared cavity surrounded by a conductive wall of finite thickness. The baffles are attached to the top and bottom sides dividing the void into three regions. The thermal resistance of the partitioned voids depends on baffles length and location. Short baffle develops a stratified region in the central gap and generates two circulation zones near the upper left and lower right corners. Long baffles, on the other hand, splits the flow into three different convection circulation cells, a cell near each side of the cavity and a third in the central gap. Increasing the baffle height increases the thermal resistance of the partitioned cavity for all gap widths. The highest increase in thermal resistance is 53% over the non baffled voids and is achieved with long baffles when located to divide the cavity into three regions of equal widths.