Phase Transition of Tetra n-Butyl Ammonium Fluoride Clathrate Hydrate in the Melting Process

摘要

We have proposed clathrate hydrate of tetra n-butyl ammonium fluoride (TBAF) as an energy storage material for air-conditioning, because the melting point can be controlled between 0°C and 27°C by changing the concentration of TBAF solutions. In this study, melting process of TBAF clathrate hydrate was investigated by using a differential scanning calorimeter (DSC). The DSC curves obtained for a TBAF concentration higher than the one at the congruent melting point, exhibited three endothermic peaks, corresponding to the melting of TBAF clathrate hydrate, transition of crystal structure of TBAF clathrate hydrate, and the melting of TBAF hydrate.