The Research Of Functional Materials On Storing Energy

With the world energy resource drying up, phase change materi- als play an important role in fields of the practical application of solar energy and waste heat in industries, and so on. Salt hydrates are ideal materials for heat storage. But the use of salt hydrates faces many problems connected with their tendency to segregate between phases and to supercool. After a certain of cycles, these troubles result in a considerable reduction of salt hydrates?heat storage capacity. In order to remove these difficulties, a lot of work has been carried out, such as adding nucleating and thickening agents. But the problem doesn seem to have been completely solved. The research proposes a new method solving above problems firstly in China: Mixing salt hydrates with compound whose vapor tension of saturated solution is very low and which can solves in water very easily, then constructing a new system, The relationship of efflo- resce tension and vapor partial tension is used to cause phase change of dehydrating-rehydrating. So the problems of supercooling and phase segregation are solved properly in principle. After experiments we get a reversible heat storage system: am- monium alum-ammonium nitrate. The dehydration and hydration be- gins at 58 590C without supercooling. The results of 30 heat- ing/cooling cycles show that there is no phase segregation when the heating temperature is 62.00C and ammonium alum: ammonium ni- trate2.5:1. The released energy (AH278.54J/g) is higher than melt- ing heat of other systems. The results of research approve the hypothesis of the mechanism of phase change taking place, and rich the study methods and contentof study field of phase change storing energy materials. The system resulted from experiments is an important finding of research field of phase change storing energy materials.