Research On Porous Matrix Composite Phase Change Thermal Storage Body In Electric Thermal Energy Storage System

It is necessary to solve the imbalance between energy supply and demand in space and time.This can be achieved through the full use of renewable energy?high-temperature industrial waste heat and clean heating.The development and application of high-performance electric thermal energy storage system(ETES)can not only solve the issues of the imbalance between energy supply and demand in intensity and time,but also play a positive role in regulating power grid for its safe and stable operation.At present,one of the key ways to improve the performance of ETES is to find new composite phase change materials(PCMs)which is different from water and magnesium iron heat storage brick to replace the traditional heat storage materials in the thermal storage unit.Based on the observation of the macrostructure and the analysis of mercury porosimeter,SiC-Si3N4/NaCl porous composite phase change thermal storage body successfully made by melt infiltration method,using SiC-Si3N4 porous ceramic composite with an average pore size of 1406.39nm and a porosity of 86.35%as the matrix and NaCl as the melt.Through the control variable method and Boltzmann's fit,the optimal preparation process of the thermal storage body was studied.It was found that the best infiltration rate of the thermal storage body was up to 79.37%when vacuum treated SiC-Si3N4 porous ceramic composite was soaked in the Molten salt at 840? for 90 minutes.SEM,EDS,XRD and DSC were used to analyze the microstructure,phase composition,thermophysical properties and mechanical properties of SiC-Si3N4/NaCl porous composite phase change thermal storage body.It was found that the recrystallization of NaCl in the thermal storage body was uniform,and it had good chemical compatibility with SiC-Si3N4 porous ceramic matrix.The results show that SiC-Si3N4/NaCl porous composite phase change thermal storage body has excellent comprehensive properties,with high temperature compressive strength is up to 7.28Mpa,energy storage density is up to 429.5kJ/kg in the phase change temperature range of 50K,thermal diffusivity is 4.404mm2/s and thermal conductivity is 3.304W/(m·K).