Calcium Hydroxide Zinc-graphite And Calcium Chloride-Graphite Chemical Heat Storage Materials Research

With the rapid development of industry and technology, fossil fuel resources are dwindling under continuous consumption. Excessive use of fossil fuels can also cause environmental problems. Therefore, the development of new energy sources becomes increasingly important. As a kind of widely used new energy, solar energy has many advantages, such as large reserves, no environmental pollution and so on. But by the changes with the season, alternating day and night, rainy weather and other factors, solar energy doesn't have a continuous and smooth output. Research on the thermal storage material can be benefit to rational and effective use of solar energy.Firstly, we use Ca(OH)2, ZnO and expanded graphite to prepare expanded graphite matrix composite heat storage material CaxZny(OH)2(x+y)-expanded graphite by co-precipitation method. Then, we improve the hydrophilic surface of graphite, and prepare modified graphite matrix composite heat storage material CaxZny(OH)2(x+y)-modified graphite. We also prepare adsorption heat storage material CaCl2-modified graphite. Then we test a series performance of the heat storage material, such as thermal decomposition temperature, storage density, cycling performance, rate of heat release and so on.We could determine the optimum calcium zinc ratio to prepare thermo-chemical heat storage material is 1.34:1 by comparing each performance of materials with different calcium zinc ratio. We also could determine the best combination of raw materials for preparing thermo-chemical heat storage material is CaO and ZnO combination by comparing each performance of materials which are prepared by different materials combinations. We improved the surface of the hydrophilic graphite to promote the thermal storage density of storage material. The thermal storage density of thermo-chemical heat storage material increased from 553.59 J/g (converted) of Ca1.146Zn0.854(OH)4-expanded graphite to 683.32 J/g (converted) of Ca1.146Zn0.854(OH)4-modified expanded graphite. The cycle performance of storage material directly affects the economy of its practical application. Experiments show that, the storage density of Ca1.146Zn0.854(OH)4-modified expanded graphite hardly decreases during recycling 7 times at the room temperature of 200?.We also test the storage density and cycle performance of CaCl2-modified expanded graphite which has adsorption heat storage properties. Experiments show that, The thermal storage density of adsorption heat storage material is 806.16 J/g,and the storage density of CaCl2-modified expanded graphite hardly decreases during recycling 13 times.