Visualization experiments and a new correlation of critical heat flux in a narrow rectangular channel

Abstract

Critical heat flux (CHF) is a crucial factor in ensuring safe operation and improving the economy of the plant. This study carried out a visualization experiment to identify the dominated parameters affecting the CHF in a narrow rectangular channel at different gap sizes (1–5 mm). The experiments were performed at pressures ranging from 1 to 4 MPa, with inlet subcooling ranging from 65 to 120 K and mass flux ranging from 350 to 2000 kg/(m2·s). A large amount of CHF correlations were compared with experimental values, and the results proved that among them Sudo correlation has the smallest prediction error. The Look-up Table method is suitable for predicting CHF in narrow rectangular channels, considering the limitation of the gap size by employing a correction factor. The increase of gap size, system pressure, inlet subcooling, and mass flux contributes to enhancing the CHF values. A new CHF correlation was proposed based on these parameters through step regression method. The comparison between prediction and experimental data demonstrates that the new correlation can accurately predict the CHF in a narrow rectangular channel with a maximum discrepancy of 20%.