Synthesis and comparative analysis of biochar based form-stable phase change materials for thermal management of buildings

Abstract

Scientific community has paid attention to organic phase change materials (PCM) as a solution for the passive thermal management of buildings because they are chemically stable, phase transition range falls within thermal comfort range, non-toxic, non-corrosive, and readily available. However, low thermal conductivity and leakage problem during phase transitions are the primary limitations associated with organic PCM that require attention in order to use in many applications. In the present investigation, suitable materials (porous biochars) for providing shape stability to organic PCM have been systematically explored. Simple impregnation method has been used for the preparation of form-stable PCM green composites. The biochar is derived from three abundant biomass, namely, sugarcane bagasse (SCB), water hyacinth (WH), and yellow oleander (YO). Binary and ternary blends of three biochars derived from the mentioned biomasses have also been studied for their candidature as supporting matrix. The morphological and structural studies confirmed that the biochar is suitable for the encapsulation of melted PCM. The composites are compared based on the heat of fusion and thermal conductivity. The highest heat of fusion is found to be 99 J/g for the PCM with a binary mixture of SCB and WH. It has been observed that thermal conductivity is highly dependent on the properties of the biochar matrix. Furthermore, thermal conductivity is found to increase by 23 % in the case of ternary mixture of biomass with PCM and decreased by 15.8 % for the case of SCB with PCM mixture than that of the pure PCM, respectively.