| Phase change heat storage materials as it can effectively solve the mismatchbetween energy supply and demand both in space and time. Especially, it is for manyhydrated salts as phase change heat storage materials have attracted attention ofresearchers because of its high latent heat, little change in volume, melting point ofthe fixed, low cost and easy availability for solar energy storage applications.KAL(SO4)2·12H2O is very important solar building heating material as a phasechange heat storage material, but phase change heat storage materialKAL(SO4)2·12H2O have problems of supercooling, leakage, corrosion, low in thermalconductivity and the insufficient long term stability to thermal cycling.Consequently, these issues that have limited widespread use of phase change heatstorage materials.In this paper, the thermal dehydration process of the phase change materialKAL(SO4)2·12H2O was investigated by thermogravimetric and differential scanningcalorimetry analysis technique firstly. The corresponding kinetic parametersincluding the activation energy and pre-exponential factor have been calculated bythe Kissinger's method under non-isothermal conditions. Then, through thefreeze-thaw experiments, the thermal properties of KAL(SO4)2·12H2O were studied.Various materials have been tested to overcome the supercooling ofKAL(SO4)2·12H2O. It is found that the effective nucleating agents containNa2B4O7·10H2O, Al2O3, CaF2and Na2SiO3·9H2O. It was studied effect of differentdosage of the same nucleating agent to supercooling degree of KAL(SO4)2·12H2O.The result indicated that their optimized proportion ofNa2B4O7·10H2O-KAL(SO4)2·12H2O was0.6:99.4, Al2O3-KAL(SO4)2·12H2O is3:97,CaF2-KAL(SO4)2·12H2O is1.5:98.5and Na2SiO3·9H2O-KAL(SO4)2·12H2O is2:98.Then studied the impact of different holding time to supercooling degree ofKAL(SO4)2·12H2O after modified. Through repetitive freeze-thaw experiments,studied the thermal cycling stability KAL(SO4)2·12H2O after modified, it hasimproved the insufficient long term stability to thermal cycling of KAL(SO4)2·12H2O.It is found that the0.6wt％Na2B4O7·10H2O is the best nucleating agent. Aftermodification, latent heat value of phase change material KAL(SO4)2·12H2O wastested by the DSC.The result indicated that latent heat value is642.8J/g. Lastly, itwas designed a heat storage tank of solar energy storage of cross season,it can makeup for leakage, corrosion and low in thermal conductivity of KAL(SO4)2·12H2O, and providing a theoretical reference in practice. Temperature distribution of heatstorage tank was studied by using ANSYS numerical simulation software. |
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