Research On Inorganic Salt/Sepiolite Fiber Phase Change Energy Storage Materials

As a new clean energy, solar energy is more concerned by people and researchers now. Since the solar energy affected by time and seasonal, people need to use energy storage materials for storage of solar energy, and make use of it when the energy shortage. Compared with energy storage way, such as sensible heat, phase change materials have unique advantages. As a result of the heat storage density, good thermal conductivity and other advantages, inorganic salt phase change materials are widely used in the field of medium and low temperature phase change energy storage. As the phase change temperature is appropriate, inorganic phase change material sodium acetate trihydrate has become the focus of the research object in the field of solar energy storage. But there is "supercooling" and "phase separation", caused by the poor thermal stability, People need to be optimized and improved so as to practical application.First of all, the different kinds of nucleating agent is added to sodium acetate trihydrate system. The system temperature changes are measured by the experimental method of cooling curve. The best type and content of nucleating agent is found to make the phase transition temperature and supercooling degree stability. And then through the experiments of methylene blue solution adsorption rate, the best acid modification and thermal modification method is selected. The mineral rich sepiolite fiber was modified to expand its pore volume, increase the adsorption rate and encapsulation more phase change materials. By using the method of melt infiltration, the sodium acetate trihydrate system adding nucleating agent and the modified sepiolite fiber composite to prepare sodium acetate/sepiolite fiber phase change energy storage materials. Finally, using scanning electron microscope(SEM), simultaneous thermal analyzer and other equipment, analysis of the microstructure, phase transition temperature, supercooling degree, thermal weight change, phase change enthalpy and aging degree by multiple melting-cooling cycle experiment. Comprehensive theory research, screening of sodium acetate trihydrate composite phase change system.The research results show that sodium acetate trihydrate system added 2% disodium hydrogen phosphate has the best nucleating effect. The best encapsulation material is sepiolite fibers through the quality ratio of 1:20, concentration of 0.6 mol/L hydrochloric acid reaction for 6 hours, and then through 400℃thermal modification for 2 hours. Mass ratio of 2:3 of the modified sepiolite fiber and the sodium acetate trihydrate adding nucleating agent is the best composite phase change system.