Critical Heat Flux in Subcooled Water Flow in a Saw-Toothed Finned Duct Under One-Sided Heating Conditions

Critical heat flux (CHF) tests on a new type of rectangular cooling tube, “a saw-toothed fin duct (SFD)” for high heat flux components, were performed under one-sided heating conditions. This tube has internal triangular fins at the heating side to enhance the CHF characteristics. The saw-toothed fin duct, which has a fin height of 3.46 mm and an installation angle of the fin of 70 deg, results in the highest CHF of 43 MW/m² at the axial flow velocity of 10 m/sec. It was found that this value is 1.3 times higher than that of a rectangular fined tube, so-called hypervapotron. Finite element analyses on the saw-toothed fin duct were also performed to examine its thermomechanical behavior under high heat flux conditions. The results show the maximum strain amplitude in the fin bases are ranged less than 0.05% under the heat flux of 20MW/m². From this result, the fatigue lifetime of the fin bases is estimated to be more than 10⁶ cycles.