Effect of bismuth oxide on the thermal storage performance of carbonate/magnesium oxide composite

Abstract

As high temperature thermal energy storage materials, Na2CO3/MgO composites have been investigated extensively. However, theirs thermophysical properties, especially thermal conductivities, need improvements to satisfy the requirements for further efficiency in energy storage system. In this paper, Bi2O3 was tried and doped into the Na2CO3/MgO composites and the possible influence of Bi2O3 on the thermal properties of the composites was investigated for the first time. Our purpose is to achieve thermal performance optimization of these composites. Depending upon SEM, DSC techniques, a detailed analysis on possible relations between thermal properties, including both thermal enthalpy and conductivity, and sintering technique was carried out in this paper. The obtained results suggested that Bi2O3 is an effective additive, which can enhance thermal conductivities of the composites significantly. With the added amount of Bi2O3 as 1-3 wt%, the thermal conductivity value could be increased from 2 to 3.5 W/(m·K) with variety in enthalpy value controlled less than 5% for the sample prepared at 830–840 °C with the ratio of Na2CO3 to MgO as 50:50.