Development of a volumetric radiation model for CFD simulation of NCM cathode calcination in packed beds

Nickel-cobalt-manganese (NCM) cathode materials are essential components of high-performance lithium-ion batteries (LIB), and calcination is a critical step that directly determines the crystallinity, particle morphology, and electrochemical properties of the final product. At 700–900 °C, radiative heat transfer becomes dominant while gas species are generated during thermal decomposition and dehydration. However, conventional computational fluid dynamics (CFD) approaches cannot simultaneously model gas generation within a cathode powder bed and radiative heat transfer from heaters, as standard radiation models require wall boundaries while gas transport requires fluid domains. Here, we develop a volumetric radiation model that enables direct application of radiative heat sources within fluid domains through a gray-medium approach employing user-defined functions. The model, validated through thermal profiling experiments in a laboratory-scale electric furnace operating at 850 °C for 20 h, revealed vertical temperature stratification of 60–80 °C during the heating phase. Parametric studies identified optimal parameters of absorption coefficient of 1/10 mm and correction factor of 0.4, achieving predictions within ±20 °C of experimental data. The validated CFD model provides a computational framework for analyzing and optimizing thermal behavior in NCM cathode calcination furnaces.