Thermal Analysis on Flat-Plate-Type Divertor Based on Subcooled Flow Boiling Critical Heat Flux Data Against Inlet Subcooling in Short Vertical Tube

Abstract

The critical heat fluxes (CHFs) and the heat transfer coefficients (HTCs) in subcooled flow boiling were applied to a thermal analysis of the flat-plate-type divertor of a helical-type fusion experimental device, which is a Large Helical Device (LHD) located in the National Institute for Fusion Science (NIFS), Japan. The incident CHF, qcr,inc, for the divertor plate with the cooling tube diameter, d, of 10mm and the plate width, w, ranging from 16 to 30mm were numerically analyzed based on the measured CHFs, qcr,sub, and HTCs for the test tube inner diameter, d, of 9mm and the heated length, L, of 48 to 149mm. The peripheral distributions of the surface heat flux and the surface temperature in the cooling tube were obtained. Numerical solutions of qcr,inc become larger with a decrease in w∕d at a fixed L. It is confirmed that the ratio of the one-side heat loading data, qcr,inc, to the uniform heat loading data, qcr,sub, can be represented as the simple equation based on the numerical solutions. The values of the qcr,inc for the tube length of 50, 100, and 150mm were estimated with various w∕d at a higher pressure.