Thermal Energy Harvesting Characteristics of Calcined Abonko Clay Mixed with Char for Building Applications

Abstract

Research into building materials with thermal energy harvesting characteristics has been of prime importance in the past decade, since materials used in building influence the temperature of the room, energy consumption, energy efficiency and the cost of construction. The goal of this research is to investigate the thermal energy harvesting characteristics of bricks made from calcined Abonko clay, Portland cement, and char from palm kernel shells, coconut shells, and acacia wood in various ratios, as well as their mechanical and thermal properties. The composite materials were analyzed using X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC), Modulus of rupture (MOR), Compressive strength test and optical and electron microscopy. Furthermore, the heat flow and thermal stresses of the composite bricks were determined using COMSOL Multiphysics modeling and simulations. The compressive strengths showed that the palm kernel char composites (5%, 10% and 15%) recorded values of ~4.60 N/mm2 , ~4.23 N/mm2 and ~4.14 N/mm2 respectively, and these values are higher than the minimum required compressive strength for bricks for construction (~3.5 N/mm2). The simulation results indicate that the char composites exhibited good energy harvesting characteristics than conventional building materials, with the acacia composite been the most effective. However, the palm kernel char composite experienced lower thermal stress distribution. It was also observed that increasing the percentage of the char in the composite resulted in a lower compressive and flexural strength, nevertheless this had positive influence on the energy harvesting characteristics of the composites. Hence building materials produced from calcined Abonko clay-cement-char composite has the characteristics to maintain thermal comfort and increase energy efficiency in buildings.