Abonnement à la biblothèque: Guest

ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

THERMOPHSICAL PROPERTIES OF SHAPESTABILIZED MgCl2·6H2O/C3N4 COMPOSITE PHASE CHANGE MATERIAL

Get access (open in a dialog) DOI: 10.1615/IHTC16.tpm.022613
pages 8808-8814

Résumé

Magnesium chloride hexahydrate (MgCl2·6H2O) has a large latent heat but low cost, which makes it great potential for thermal energy storage. However, the inherent supercooling and phase separation of the hydrated inorganic salts severely limit the practical application of magnesium chloride hexahydrate. In order to develop a high performance magnesium chloride hexahedral magnesium chloride phase change material, a new phase change material (PCM) is prepared by compositing MgCl2·6H2O with the graphitic carbon nitride (g-C3N4) of different mass fractions, and its thermophysical properties are measured. The results show that the phase transition temperature of MgCl2·6H2O is 119 °C and the phase change enthalpy is 120 kJ / kg. The composite phase change material has the same melting point, but a lower phase change enthalpy. The phase change enthalpy reaches 109.5 kJ/kg, with a the C3N4 mass fraction of 80%, and increases with the mass fraction. The pure MgCl2·6H2O is easy to absorb the water in air and the mass change reaches up to 5% in just one hour. Compositing MgCl2·6H2O with C3N4 helps prevent the hydrate absorbing water. With the C3N4 mass fraction of 85%, the mass change can be limited within 0.4% in two hours. The composite phase change material also has a better thermal stability. The thermal gravimetric analysis (TGA) test shows the weight loss rate of the composite PCM at 300 °C is 10.92% less than pure MgCl2·6H2O. The MgCl2·6H2O/C3N4 composite has a thermal conductivity of 0.51 W/m K, greater than the pure MgCl2·6H2O. And the composite still suffers a high subcooling degree. But after adding 2% SrCl2·6H2O, the high subcooling degree of MgCl2·6H2O/C3N4 around 25 °C can be almost eliminated. On overall, compositing MgCl2·6H2O with C3N4 enhances the thermophysical properties of MgCl2·6H2O, making it a great choice for medium-temperature thermal energy storage materials.