Phase diagram of the ternary system lauric acid–capric acid–naphthalene

The mixture of lauric acid and capric acid is a potential latent heat storage material. However, its eutectic melting temperature is quite high for low-temperature thermal energy storage. Addition of naphthalene is proposed. The ternary system lauric acid–capric acid–naphthalene has been investigated by differential scanning calorimetry (DSC), visual polythermal and chromatography of gases. The phase diagram is of an incongruent eutectic type. The eutectic mixture contains 18.4 mol% lauric acid, 63.1 mol% capric acid and 18.5 mol% naphthalene and melts at 13.3 °C. The peritectic mixture contains 32.4 mol% lauric acid, 48.2 mol% capric acid and 19.4 mol% naphthalene and peritectic temperature of 16.2 °C. The incongruent compound was analysed to be CH3(CH2)10COOH·CH3(CH2)8COOH. The melting temperature of the lauric acid–capric acid–naphthalene eutectic mixture makes it suitable for cooling applications.