Enhanced radiation heat transfer performance of Alumina-Spinel composite sphere with hollow structure for rapidly ultra-high temperature thermal storage/release process

Abstract

Heat storage technologies for high temperatures have recently been gaining increasing attention. For heat storage applications at high temperatures, such as industrial regenerative burner systems, the impact of radiant heat transfer on the efficiency of rapid heat storage and release cannot be ignored. Hence, the development of heat storage materials with high infrared radiation absorption is of great significance for energy saving and CO2 emission reduction. Consequently, this study innovatively proposes an advanced composite heat storage material, composited by alumina and a Fe-Co-Mn-Al spinel, with the aim of improving absorptivity. A medium-entropy approach is employed to improve IR absorptivity of alumina. Through the strategic adding of various transition metal oxides, the radiative absorptivity of the alumina material in the 600–1200 °C range increased from an initial 0.2 to an impressive 0.8, provided that doping additives remain below 10 wt%. The high-temperature heat storage material balances cost, heat recovery efficiency and thermal stability. In addition, the heat storage material is prepared as a hollow sphere to further enhance the heat storage density of rapid heat storage/release and reduce cost. Multi-scale numerical simulations are carried out to reveal the heat transfer enhancement mechanisms of modified materials and hollowing. radiative modification can significantly increase the heat storage and release capacity, especially at ultra-high temperatures above 1000 °C. Experimental evaluations using an actual regenerative burner further confirmed the heat recovery performance of this novel heat storage sphere. Comparing with conventional regenerative burner system, heating power remarkably increased by 24.6 %, and the heat storage density of packed bed improved by 16.7 %. This study promises to significantly improve the efficiency of rapid heat recovery at high temperature.