Experimental Study On Composite Heat Storage Material With Metal And Molten

With the rapid development of global industrialization and the improvement of people's standard of living, and the heavy exploitation and utilization of energy, the problem of energy attracts more and more attention. Hence, it's very important to develop an advanced energy-saving technology, and on the other hand, the research of energy storage is also a crucial measure to release the unbalance of energy supply and requirement. So the relation between energy and the development of society is also quite tight. New energy and materials are the two critical parts of this technology, which is vital to the development of our country. A great deal of energy will be consumed because of the rapid development of industry and agriculture, and also because of the improvement of standard of living; on the other hand, the environment pollution are needed to be treated properly. Hence, to develop new energy and new energy-materials is a great task that should to be achieved in the 21st century.At present, the heat storage technology has the sensible heat thermal storage and latent heat thermal storage. Latent heat thermal storage has the advantage of large heat storage quantity per unit weight or volume and good chemical stability and safety, but when the phase changes the heat conductivity is poor at the interface of liquid and solid. Sensible heat thermal storage has the advantage of good chemical and mechanical stability, but the heat storage amount per unit weight or volume is small, and temperature change is remarkable during heat charge-discharge process. So the application of a single dielectric material is quite limited. The ideal heat storage material should satisfy with some conditions: high density of heat storage, good ability of heat conductivity, little change of volume, no over-cooling, good chemical stability, safe and economic, and easy to acquired from the nature or developed.To increase the velocity of phase-change, the thermal efficiency, the density of heat storage, and long-time stability are the important tasks at present. In this paper, the process of preparing a kind of high quality composite heat storage material was established, following a series of experimental studies.We successfully prepared the high quality composite heat storage materials by combining foam metal nickel base and some kinds of molten salts at certain temperature. The foam metal nickel has the advantage of good heat conductivity and the molten salt has the advantage of large heat storage quantity per unit weight or volume. So this new kind of material overcome the disadvantage of both of sensible heat thermal storage materials and latent heat thermal storage materials, at the same time, it keep the advantage of these two kinds of materials. Structures and properties of these materials were studied by SEM, X-ray diffraction and TG-DTA techniques. And the effects of composite time on percentage of phase-change material and composite temperature on the heat storage density were discussed. Then the optimum conditions and process of preparing this material was established.We use X-ray diffraction to analyze whether there is any chemical reaction in this material. And the result shows that the main constituent is metal nickel and molten salt, and it's consistent with the expected purpose. After being analyzed the samples by SEM, we can know that the molten salt distributed in the porous foam metal nickel basisuniformly. When the temperature surpass the melting point of molten salt, the molten salt will melt and adsorb the latent heat, and the heat will not efflux because of the tension of capillary. Andihe metal framework will divide the molten salt into many tiny heat storage units. The heat conductivity of these units won't be worse during heat charge-discharge process. After analyzing by TG-DTA, the result shows that the composite temperature is higher than molten salt 50-150 centigrade, and if the temperature is higher, the density of heat storage will decrease because of the drop of the weight of the composite materials. The experiments prove that the best composite time is about 2-3 hours; the proportion of molten salt is relatively high in the composite materials, resulted the great density of heat storage. Provided more time, will it be easy to produce some other substances. And the calculated result shows that the compound heat storage material has high density of heat storage and coefficient of heat conductivity.The optimum process of preparing samples is the following: the combining temperature is 50-150 centigrade higher than the temperature of phase change of the molten salt; the best combining time is 2-3 hours; the new composite heat storage materials prepared following this process has the advantage of high heat charge-discharge rate, high density of heat storage and high coefficients of heat conductivity and also the advantage of corrosion resistant. This new composite heat storage material not only keeps the advantage of sensible heat thermal storage materials and latent heat thermal storage materials, but also overcome their disadvantage , so it has the advantage of high heat charge-discharge rate, high density of heat storage. If this material was applied to recycle industrial waste heat, the waste heat will be recovered as much as possible. Hence, the application and development prospect of this new composite heat storage material is quite promising.