Experimental study of boiling heat transfer characteristics of multi-elbow cooling system under one-sided heating with long section for fusion divertor cooling

Abstract

In this study, heat transfer experiments were conducted under one-sided heating conditions using water as the coolant and an electron gun as the heat source. To evaluate the boiling heat transfer characteristics of the swirling flow formed by a multi-elbow piping, heat flux by the electron gun is deposited on the region of 60 mm-section in the flow direction corresponding to 0.5 D (inner diameter of the flow channel) to 6.5 D from the elbow outlet, and then temperature distributions in the flow, circumferential and radial directions were measured. The experimental results showed that the wall temperature cooled by the swirling flow generated downstream of the multi-elbow was lower than that obtained in the case of turbulent flow in the straight pipe when irradiated with the same value of heat flux. Thereby, the heat fluxes at the boiling start and DNB points obtained in the multi-elbow case were higher than those in the straight pipe case. These results imply the superior cooling performance of multi-elbow system.