Investigation of the thermal efficiency of hollow bricks filled with bio-organic phase change material mixture

A bio-organic phase change material (BIO-PCMs) is proposed to replace petroleum-based PCMs currently used in buildings, specifically for application in the city of Adrar, known for its arid climate. Fatty acids were examined based on several criteria, such as price, availability, risks, and renewable origin. A suitable fatty acid candidate for the PCM, based on stearic and myristic acids, was identified. To investigate the thermal properties of the proposed PCMs, eutectic mixtures of myristic and stearic acids were prepared and synthesized in a series of mixtures with different proportions. An optimal PCM composition of 70 % myristic acid (MA) and 30 % stearic acid (SA) was developed, offering high thermal stability and effective energy storage. Experimental testing using differential scanning calorimetry confirmed its melting temperature at 35 °C. A numerical investigation using COMSOL Multiphysics software was also conducted to quantify the thermal effect of incorporating the experimentally selected PCMs into a brick wall under severely hot summer conditions in Algeria's Sahara. Two wall configurations were designed for comparison: one in which the PCM was integrated into the brick structure, and the other serving as a reference without PCM. The results showed that placing the PCM near the outer wall surface lowered indoor temperatures by 2.8 °C and delayed peak heat transfer by 2 hours. Also, there was 58 % reduction in inner surface heat flux for this configuration when ccompared with hollow clay wall without PCM. The study confirmed its suitability for hot climates like Adrar, with potential for further optimization in varying seasonal conditions.