Adaptive Mesh Refinement for LES-DEM Study on Heat and Mass Transfer in a Particle-laden Transcritical Jet Flow

During the feeding process of supercritical water fluidized bed reactors, the particle-laden jet undergoes a transcritical condition upon entering the container, leading to complex and highly coupled flows. To reduce computing resources, we propose an adaptive mesh refinement (AMR) strategy for particle-laden transcritical jets, that is characterized by temperature and velocity fields. When applied to an LES-DEM study, the cell count required is significantly reduced while maintaining a satisfactory accuracy, minimizing the required computational resources and facilitating further study for large-scale reactors. The results indicate the presence of a thermal-shield interface between the jet and the ambient fluid, which dissipates rapidly upon exceeding the critical temperature. Increased particle transportation across this thermal-shield into the ambient fluid notably enhances particle heating efficiency. As the jet injection velocity increases, the Kelvin-Helmholtz instability gradually strengthens interfacial waves, leading to an enhanced stirring up of particles from the primary jet flow, thereby intensifying particle heating. However, the increased jet velocity introduces more low temperature water and particles, causing a decrease in the overall temperature and an unfavorable condition for efficient particle heating. The compensatory interaction of these factors results in an injection velocity that optimizes efficient particle heating.