Lannea kerstingii seed oil for sustainable thermal energy storage: Thermophysical properties, medium-temperature stability and interaction with common engineering metals

In the quest to enhance sustainability of energy processes, vegetable oils like Lannea kerstingii seed oil (LaKSO) offer renewable and environmentally friendly alternatives to conventional thermal oils in medium-temperature applications such as concentrating solar power (CSP). This study aims to evaluate the thermophysical properties of LaKSO and assesses its compatibility with common engineering metals to determine its suitability as a heat transfer fluid and thermal energy storage material up to 210 °C. Thermophysical properties, including specific heat capacity , density, viscosity , thermal conductivity , flash point, and melting point, were measured for fresh oil and oil aged at 210 °C for 500 and 1000 h (according to ASTM D6743 ), both in the presence and absence of metals. A series of characterizations, including thermogravimetric analysis and Fourier transform infrared spectroscopy , provided insights into the thermal stability of the oil. LaKSO exhibited a high flash point of 220 ± 10 °C and maintained good thermal stability after 1000 h of aging at 210 °C. While viscosity increased at 40 °C, it remained comparable to that of fresh LaKSO at 100 °C. However, oil saturation resulted in an increased melting point with aging. LaKSO demonstrated compatibility with stainless steel and aluminum ; however, copper and galvanized steel accelerated oxidation , indicating their unsuitability for medium-temperature applications. The thermophysical properties of LaKSO were comparable to those of previously investigated vegetable oils proposed for similar applications. Overall, LaKSO shows promising potential as a sustainable heat transfer fluid and thermal energy storage material suitable for use in CSP applications. • Thermophysical properties of Lannea kerstingii seed oil (LaKSO) are determined. • LaKSO exhibits good thermal stability after 1000 h of aging at 210 °C. • Density of LaKSO remains stable throughout aging at 210 °C. • LaKSO’ thermophysical properties are similar to those of other vegetable oils. • 316L stainless steel and aluminum are suitable metals for use with LaKSO.