A New CHF Correlation Scheme Proposed for Vertical Rectangular Channels Heated From Both Sides in Nuclear Research Reactors

In this study, an investigation was carried out to identify the important parameters affecting critical heat flux (CHF) in rectangular channels, focusing on the effects of flow direction, channel inlet subcooling from 1 to 213 K, the channel outlet condition extending from subcooling of 0–74 K to quality of 0–1.0, pressure of 0.1 to 4 MPa, water mass flux of −25,800 to + 6250 kg/m²s, and channel configuration. In particular, the effect of the outlet subcooling in upflow and downflow on the CHF was quantitatively investigated. As a result of this study, a new CHF scheme covering downflow, countercurrent flow, and upflow was established in the rectangular channels within the ranges of parameters investigated in this study.