Abstract
Palm stearin is the heavy fraction obtained during palm oil refining. It consists mainly of saturated fatty acids and is often an unwanted by-product that reduces the economic efficiency of the processes. Although it is currently used in the manufacture of margarine or industrial vegetable fats, the increase in palm oil production will lead to higher production of palm stearin. The composition, low cost and physicochemical characteristics of palm stearin make it an ideal raw material for obtaining phase change materials for thermal energy storage in solar thermal energy systems. This work explores the esterification of hydrogenated palm stearin (HPS) for obtaining phase change materials with suitable properties for application. The esterification conditions were studied using low and high molecular weight alcohols, like ethanol, butanol and cetyl alcohol, according to Fischer's esterification principles. The esters formation was characterized by attenuated total reflectance infrared spectroscopy. For both HPS and products obtained, melting and solidification temperatures and enthalpies, and heat capacity were determined by DSC according to ASTME793-06(2018) and ASTME1269-11(2018). A crude wax was obtained by esterification of the fatty acids present in palm stearin in all cases. Among the esters produced, the one obtained by using cetyl alcohol, which has a melting temperature of 55.9 °C and an enthalpy of fusion of 257.26 kJ/kg, stands out. This novel PCM is presumed to have an optimal performance for heat storage applications in low temperature solar thermal systems (50°C - 90°C), for hot water supply and space conditioning.
