Preliminary assessment of a mixture of capric and lauric acids for low-temperature thermal energy storage

A mixture of capric and lauric acids was evaluated as a possible phase-change media suitable for Philippine low-temperature thermal-energy storage systems. The properties of different combinations of acids were verified against existing literature data with the use of a differential scanning calorimeter. Classical evaluation techniques were employed to determine the required thermodynamic, kinetic, and other physical properties. The accuracy of the set-up was determined and phase transitions were observed by performing a series of thermal cycles. To authenticate the long-term stability and reproducibility of the combination, 120 thermal cycles were carried out using a fabricated equilibrium cell. The observed lowest temperatures averaged 11.63 degrees C. The material remained physically stable. However, the energy density requires further design improvement. No usable storage medium has as yet been found because the cooling effect occurred in a time that is too short for practical use. (C) 1998 Elsevier Science Ltd. All rights reserved.