Evaluation of the thermal energy storage performance of calcium-magnesium binary composite salt hydrates
Salt hydrate as a type of thermochemical energy storage materials involves reversible chemical reactions for the storage and release of heat during the processes of adsorption and desorption.It has high thermal energy storage density and is suitable for long-term thermal energy storage.Moreover,it can be combined with solar energy utilization,which can reduce the dependence on fossil energy.In this study,effect of different porous matrix,microporous molecular sieve(13X)and mesoporous diatomaceous earth(WSS)on the thermal energy storage performance of calcium-magnesium binary composite salt hydrates was investigated based on MgCl2 and CaCl2 with a molar ratio of 1:2.Firstly,the pore structure,sorption isotherm and cycle stability of the developed two types of calcium-magnesium binary composite salt hydrates were compared.A two-dimensional model of a honeycomb thermal energy storage unit was used to analyze the storage/release performances of the developed two composites.Results showed that the 13X had smaller pore volume,larger specific surface area than WSS.Due to the impregnation of MgCl2/2CaCl2,the pore volume,specific surface area and porosity of calcium-magnesium binary composite salt hydrates had been reduced compared to those of corresponding porous matrix.Both MgCl2/2CaCl2 composites showed higher sorption capacity than that of the porous matrix.Moreover,the Polanyi adsorption potential theory could describe the sorption isotherm of the calcium-magnesium binary composite salt hydrates well.Furthermore,the simulation results showed that the thermal energy storage density of the WSS20 was 371.94MJ/m3,which was higher than that of 13X17,as well as the energy released power and recovery efficiency.The WSS20 could be used for storing/releasing thermal energy more than 47 times,while the 13X17 showed bad stability even within 10 cycles.Therefore,considering both thermal energy storage density and cycle stability,WSS20 was more suitable for storing thermal energy.
thermochemical energy storagecalcium-magnesium binary saltwakkanai siliceous shalecyclic stabilitythermal energy storage density
国家科技期刊平台
NSTL
万方数据
