Critical-Heat-Flux Experiment on the Screw Tube Under One-Sided-Heating Conditions

Development of high-heat-flux components such as the divertor plate of fusion experimental machines is essential for removal of high heat loads with heating on one side. For this purpose, the authors machined a tube with an inside wall like a nut, namely, a screw tube, to enhance heat transfer efficiency and simplify the machining process. The screw tube is compared with a swirl tube, originally developed by Oak Ridge National Laboratory, and the Hypervapotron, developed by Joint European Torus (JET). The spirally machined inside wall can enlarge the heat transfer area and make a little vortex flow only close to the wall. The performance of the screw tube is characterized by a critical-heat-flux experiment that uses water flow velocities ranging from 4 to 20 m/s with a water inlet pressure of 1.0 MPa. As a result, the screw tube has a higher incidence of CHFs compared with the smooth tube and the Hypervapotron and performs similarly to the swirl tube at identical flow velocities.