Study on energy storage performance of thermally enhanced composite phase change material of calcium nitrate tetrahydrate

In this study, a layer of nano-alumina film was coated on the EG surface and the matrix material was then mixed with molten calcium nitrate tetrahydrate salt to form a CPCM (MEG-CN4W). The prepared materials were characterized by Fourier transform infrared spectroscopy, X-ray diffractometer, contact angle measurement, thermal conductivity measurement and other techniques. When MEG has a mass ratio of 8% ~ 10%, the average phase transition enthalpy value of MEG-CN4W is 123 J/g, the phase transition temperature is 42.7 °C, and the peak temperature is 49.7 °C. The average activation energy of this CPCM is lower than that of CN4W. The thermal conductivity is 13 times higher than CN4W. On this basis, the cyclic thermal stability analysis of CPCM was carried out. MEG-CN4W was found to be stably and highly adsorbed on the expanded graphite surface after 200 heat storage-release cycles without liquid leakage. The phase change temperature and enthalpy value remained nearly unchanged, indicating that the prepared CPCM has potential application prospects. [Display omitted] •A layer of nano-alumina film is coated on EG surface to improve adsorbing ability of CN4W.•Thermal conductivity of MEG-CN4W is 13 times higher than CN4W.•Apparent activation energy of MEG-CN4W is lower than that of CN4W.•Average phase transition enthalpy is 123 J/g after 200 heat storage and release cycles.•CN4W is stably adsorbed on MEG surface after 200 heat storage and release cycles.