Effects of physical properties of supercritical water on heat transfer characteristics of single particle within a particle cluster

The complex physical properties of supercritical water (SCW) make the heat transfer characteristics of particles within a particle cluster complicated. The heat transfer characteristics of single particle within a particle cluster in SCW, influenced by surrounding particles, have not been effectively explored. The numerical simulations were conducted to investigate the heat transfer characteristics of particle clusters in SCW under different conditions. The results were compared and analyzed with those from constant property flow. It was found that Reynolds number (Re) and the void fraction of particle cluster have no special effects on the variation trends of Nusselt number (Nu) for the focused particle. However, the particle temperature had a significant effect on the variation trends of Nu. The effect of Re on the heat transfer rate exponent (η) of the focused particle can be divided into two zones: a significant effect zone and a non-significant effect zone. The effect of void fraction on η in the non-significant effect zone was minimal. Within the non-significant effect zone, η decreased with the increasing particle temperature. In the significant effect zone, the variation trends of η became more complex. The fundamental reason for this series of phenomena is the changes in distribution of physical properties. A model for η was developed for the non-significant effect zone. This model can filter out the effects of Re and certain particle cluster spatial configurations, and it demonstrates good predictive performance.