Assessment of Non-dimensional Parameters for Static Instability in Supercritical Down-Flow Channels

Abstract

An analytical study of static instability of supercritical down-flow is presented herein. The study was conducted as part of an ongoing study to help identify relevant non-dimensional parameters governing supercritical flow instability in parallel channels. By and large, static instability was uncovered to be the dominant mode in down-flow, but oscillatory instability was found possible. Results are presented for H₂O and CO₂. It was found that often the static instability boundary occurred when the channel outlet temperature was close to the pseudo-critical temperature, sometimes even less than the pseudo-critical temperature. The study also indicates what parameters need to be altered, and in which direction, to improve system stability. Three different pressures for water were examined and non-dimensional parameters were assessed and discussed.