A glimpse into the sub-ambient performance of edible vegetable oils for cold thermal energy storage: composition, thermophysical properties, and thermal stability

A systematic evaluation of six edible oils—sesame, sunflower, corn, linseed, sacha inchi, and soybean—was conducted to assess their suitability as bio-based materials for cold thermal energy storage (CTES) within a temperature range of −60.0 °C to 20.0 °C. Oils were extracted by cold pressing and analyzed by Fourier-transform infrared spectroscopy (FTIR), gas chromatography with a flame ionization detector, differential scanning calorimetry, simultaneous thermal analysis coupled with an FTIR-detector, and laser flash analysis. The results revealed similar functional groups among the oils but distinct fatty acid distributions, which governed their thermal transitions and stability. All samples exhibited high thermal stability up to ∼300.0 °C, with total stored energy ranging from 96.72 J·g −1 to 113.43 J·g −1 , and thermal conductivities between 0.124 W·m −1 ·K −1 and 0.197 W·m −1 ·K −1 . Sunflower oil demonstrated the most favorable phase change material (PCM) behavior, characterized by the highest enthalpy of fusion (70.00 J·g −1 ), narrow endo/exothermic peaks, low subcooling, and high cycling stability, attributed to eutectic-like behavior. The remaining oils, while less efficient as PCMs, performed robustly for sensible heat storage (SHS) and as heat transfer fluids (HTFs). These observations find vegetable oils to be promising biodegradable CTES candidates and underscore the critical role of fatty acid composition in tailoring thermal properties for cryogenic and refrigeration applications.