Influence of equivalent diameter on heat transfer and flow characteristics of supercritical water

A numerical simulation was carried out to study the heat transfer and flow characteristics of supercritical water in circular tube and annular channel using FLUENT software. According to the comparison of different turbulence models, SST model which is relatively better under supercritical condition was selected in this paper. Distributions of heated wall temperature, temperature and velocity in boundary layer in circular tube were compared with those in annular channel to study the influences of hydraulic equivalent diameter and thermal equivalent diameter on heat transfer and flow characteristics of supercritical water. The results show that hydraulic equivalent diameter plays an important role, while the influence of thermal equivalent diameter can be neglected. Correlations in annular channel can be established based on that in circular tube, and further researches should be carried out to study other impact factors on heat transfer and flow characteristics of supercritical water. (authors)