Thermo-Mechanical Assessment of Bio-based Insulating Material Using Phase Change Materials and Date Palm Fibers

Abstract

To mitigate extreme temperature fluctuations in arid southern Algerian cities, developing an internal thermal environment that is either independent of or only marginally influenced by external conditions is a viable solution. In this study, we successfully created a eutectic mixture of animal and plant fatty acids, excluding petroleum sources, consisting of 70% myristic acid (MA) and 30% stearic acid (SA). This phase change material (PCM) was then impregnated into date palm fiber waste (DPF) using a vacuum technique. The melting points of both the eutectic mixture and the impregnated date palm fiber were measured at 35°C and 34.5°C, respectively. Clay bricks, which are widely used in Algerian construction, were prepared with 75% dune sand and 10% lime. Date palm fibers impregnated with PCM were added in varying proportions (0.5%, 1%, 1.5%, 2%) to test the mechanical and thermal properties of the bricks. The results showed an improvement in thermal insulation, with a reduction in thermal conductivity by 11% for bricks containing 2% impregnated palm fibers. The compressive strength of these bricks remained within acceptable limits, regardless of whether the PCM was in a solid or liquid state. Numerical simulations showed that adding MA-SA/DPF to clay bricks contributed to a 30% reduction in outward heat flow in winter and a 25% reduction in inward heat flow in summer. This, in turn, resulted in a corresponding decrease in energy consumption.