Study On Regulation Of Phase Change Performance Of Sodium Phosphate Dibasic Dodecahydrate

Rapid development of the modern economy depends on massive consumption of energy.The energy of the modern society mainly comes from fossil fuel of coal,but severe damage to the environment is caused by application of the fuel.Therefore,it is urgent to find efficient and clean energy under the current situation of acceleration of replacement of old kinetic energy by new energy.Research of the phase change heat storage technology is a key focus in recent years,and the mode that a large amount of heat is absorbed or released by phase change materials during change of the state of the phase change materials is adopted as the heat storage mode of the phase change heat storage technology so that the heat is utilized.Due to the largest advantage of cleanness and no pollution of the technology,the problem of mismatch between supply and demand of solar energy can be relieved effectively when the technology is applied in the field of solar heat storageAs an inorganic hydrated salt crystal phase change heat storage material with large latent heat of phase change and suitable temperature of phase change,sodium phosphate dibasic dodecahydrate was focused and studied widely.However,it was found during practical study that great influences were produced on the crystallization process of sodium phosphate dibasic dodecahydrate by different cooling temperatures,but there were little analysis and study about the aspect.In the perspective of practical application,study was focused on three aspects including supercooling degree improvement,heat release efficiency improvement and cycle stability improvement of sodium phosphate dibasic dodecahydrate through experiments and centralized analytical testing means in the paperFirstly,through combination of Raman spectroscopy with X-ray diffraction analysis,the phase composition of sodium phosphate dibasic dodecahydrate was analyzed.After the cycle stability of sodium phosphate dibasic dodecahydrate was tested through multiple times of thermocycling experiments,it was found that the higher the cooling temperature was,the worse the cycle stability was,and an obvious phenomenon of phase separation was produced after twenty cycles were conductedSecondly,the effects caused by addition of nucleating agents and graphene nanoplatelets on the supercooling degree and heat release time of sodium phosphate dibasic dodecahydrate at different cooling temperatures were studied through contrast experiments.Through combination of DSC testing analysis,Raman spectroscopy analysis and X-ray diffraction analysis,the effects caused by addition of the nucleating agents and graphene nanoplatelets on the thermal performance,supercooling degree and heat release time of sodium phosphate dibasic dodecahydrate were determined.It was shown through experimental results that good comprehensive performance was given to a sample with 3 wt%of sodium metasilicate nonahydrate and 3 wt%of graphene nanoplatelets and a sample with 3 wt%of alumina and 2 wt%of graphene nanoplatelets.It was found through tests of cycle stability of the two samples that the lower the cooling temperature was,the worse the cycle stability was,and the phenomenon of delamination was producedFinally,the cycle stability of the composite phase change material was improved through addition of sodium carboxymethyl cellulose(CMC).It was proved through multiple experiments that the composite phase change material with 3 wt%of alumina,2 wt%of graphene nanoplatelets and 3 wt%of CMC was provided with good phase change performance and excellent cycle stability,and 80 cycles can be maintained The supercooling degree,heat release efficiency and cycle stability of the performance-regulated sodium phosphate dibasic dodecahydrate were improved significantly,so that experimental foundation was laid for promotion of application of sodium phosphate dibasic dodecahydrate.