Analytical Study on Characteristics of Critical Heat Flux under High Subcooling and High Velocity Conditions.

Abstract

A quantitative analysis of critical heat flux (CHF) under high mass flux with high subcooling was successfully carried out by applying a new transition region model for a thin liquid sublayer on the heated walls to the existing model of vapor blanket over the thin liquid sublayer. The CHF correlation proposed in this study could predict well experimental data obtained using circular tubes of 2.5 to 3 mm in diameter, 100 to 290 mm in length, 0.34 to 2.6 MPa and 13 to 210°C in inlet subcooling, and rectangular channels of 3.5 mm in gap, 150 mm in length, 0.5 to 3.1 MPa and 13 to 166°C in inlet subcooling, revealing a unique feature that the critical heat flux is proportional to around G0.8, where G is the mass flux, at high mass flux of the dimensionless mass flux G* ranging from 350 to 4700 under the subcooled condition at the exit of the channel.