Testing method of phase change temperature and heat of inorganic high temperature phase change materials

Abstract: An analytical temperature model and an enthalpy difference function, based on lumped parameter method and assumption of rectangular effective specific heat, are presented in this study, which can measure the enthalpy change of inorganic salt high temperature. It is easy to carry out in practicable test, because an automated test equipment is designed to measure and record the T-history curves of the PCMs and “Valley, Bottom, and peak” and “Peak, Top, and Valley” criteria are proposed to select the starting temperature of phase-changing process (TS ), the ending temperature of phase-changing process (TE ) and the melting point (Tm ) of the PCMs. The binary eutectic LiNO3–NaNO3 (5.5:4.5, mass ratio), LiCl–NaCl (7:3, mass ratio) and Li2CO3–Na2CO3 (4:6, mass ratio) are tested, whose melting point and heat of fusion are (198.9°C, 255kJ/kg), (559°C, 460kJ/kg) and (499°C, 374kJ/kg). The maximum deviation between measurements and the values from DSC and references is less than 8%. It can be seen that with this method it is possible to obtain both melting point and heat of fusion in a simple way which will be of great help in selecting heat storage material in solar-energy and industrial waste heat utilization and in the subsequent design of a thermal energy storage system. [Copyright &y& Elsevier]