Measurement of latent heat of tetra-n-butylammonium bromide (TBAB) hydrate

Tetra-n-butylammonium bromide (TBAB) hydrate has favorable properties as a thermal storage material. For example, the phase change temperature, which is from 0 to 12 °C, is suitable for use in air conditioning, and the latent heat is relatively large. Thus, the thermophysical properties of TBAB hydrate, such as latent heat, are of considerable interest. In this study, a large size of pure TBAB hydrate crystal was formed and the latent heat of TBAB hydrate was measured by melting the crystal. The latent heat of TBAB hydrate type 1 was estimated to be 210 kJ kg−1, while that for type 2 hydrate was 224 kJ kg−1. These values agree with literature values estimated from the variation of specific enthalpy of TBAB hydrate slurry, but are 10% larger than the other literature values measured using DSC.