Optimization Of Concrete-molten Salt Composite Heat Storage Structure

Under the dual background of environmental pollution and efficient use of energy,it is particularly important to design efficient heat storage structures for electric heat storage devices.Solid concrete heat storage has relatively good application prospects,but there are still many problems with solid concrete heat storage,which limits its application and promotion.Adding the encapsulated molten salt phase change layer to the concrete heat storage device can increase the heat storage of the concrete heat storage device and improve the economy of the entire device.In this paper,the concretemolten salt composite heat storage structure is numerically simulated,and its heat storage structure is optimized.Numerical simulation of the heat storage process of concrete and concrete-molten salt composite heat storage body under the heating method of the side wall surface.When the molten salt phase change layer is quaternary mixed 1 nitrate,the thickness of the phase change layer is 100 mm,and the distance between the phase change layer and the heating surface is 95 mm,the simulation results show that it is necessary to consider natural convection in the phase change layer during heat storage Compared with neglecting natural convection,the natural convection melting time is shortened by 56.25%,and the heat storage after 8 hours is increased by 6.8%.By comparing the corresponding zones,the heat storage in the first zone of the composite body is reduced,reducing the temperature difference from the heating surface;the absorption of latent heat in the second zone and the further utilization of the heat storage capacity of the concrete in the third zone result in the heat storage of the composite regenerator after 8 hours This is an increase of 2.36% compared to concrete.The composite heat storage body heated by the central heating tube and containing quaternary mixed 1 nitrate in the molten salt phase change layer is numerically simulated.The results show that after heating for 8 hours,when the phase change layer is 75 mm away from the central heating tube and the thickness of the phase change layer is 140 mm,the heat storage of the composite is 26747.50 kJ.Compared with concrete with the same structure,the heat storage structure has increased heat storage by 5830.6 kJ,which further shows that the combination of sensible heat and latent heat is effective.This advantage has certain versatility.The molten salt in the phase change layer was selected as the self-produced solar salt,quaternary mixed 1 nitrate and quaternary mixed 2 nitrate,and the composite heat storage structure was numerically simulated under the heating method of the side wall.The results show that for the above three molten salts and heating for 8 hours,when the phase change layer is 230 mm away from the heating surface and the thickness of the phase change layer is 60 mm,the heat storage of the composite regenerator is the largest.The maximum heat storage of the composite heat storage body made of solar salt is 71607.78 kJ,which is the largest of the three.Compared with the concrete heat storage body,the heat storage increased by 36701.07 kJ,with a growth rate of 105.14%.It is useful to install a molten salt phase change layer in the concrete heat storage body,which can significantly increase its heat storage.