Analysis and experiment of the hypervapotron mock-up for the EAST upgrade
During the EAST upgrade, the peak heat flux applied on the first wall components will be 2 MW/m2, which requires powerful cooling concept to decrease the component temperature, in order to simplify the material requirement and armor/heat sink module design. Hypervapotron is a promising method for high heat transfer coefficient, which bases on sub cooling boiling phenomenon, and has the potential to support the demand in several years (up to 20 MW/m2 with strong armor), and is chosen to be a candidate. The design contains a copper heat sink and uses water as coolant, a series of CFD analyses are performed to optimize the design, and a mock-up based on this optimization is assembled on a high heat flux test facility which employs electromagnetic induction heating and high speed photography; during the experiment under the required working conditions, the flowing status and thermal parameters are recorded. The analysis and experiment confirm the performance of the hypervapotron concept and the feasibility of the use in the EAST upgrade project.
Experimental optimisation of a hypervapotron® concept for ITER plasma facing components
Abstract Historically developed for cooling of klystron electronic tubes, metallic hypervapotron® prototypes with different width were manufactured for high heat flux plasma facing components (PFC) applications. They were critical heat flux (CHF) tested on the European 200 kW electron beam facility (FE200), the 54 measured values have shown their good performances—up to 25–30 MW/m2 at low axial velocities (2–6 m/s)—interesting for ITER divertor dome and vertical target design. An important conclusion is that CHF decreases when the width increases.
A New Facility for Measurements of Three-Dimensional, Local Subcooled Flow Boiling Heat Flux and Related Critical Heat Flux for PFCs
Abstract In the development of plasma-facing components for fusion reactors and high-heat-flux heat sinks (or components) for electronic applications, the components are usually subjected to a peripherally nonuniform heat flux. Even if the applied heat flux is uniform in the axial direction (which is unlikely), both intuition and recent investigations have clearly shown that both the local heat flux and the eventual critical heat flux (CHF) in this three-dimensional (3-D) case will differ significantly from similar quantities found in the voluminous body of data for uniformly heated flow channels. Although this latter case has been used in the past as an estimate for the former case, more study has become necessary to examine the 3-D temperature and heat flux distributions and related CHF. Work thus far has shown that the nonuniform peripheral heat flux condition enhances CHF in some cases. To avoid the excess costs associated with using electron or ion beams to produce the nonuniform heat flux, a new facility was developed that will allow 3-D conjugate heat transfer measurements and two-dimensional, local subcooled flow boiling heat flux and related CHF measurements. The configurations under study for this work consist of (a) a nonuniformly heated cylinder-like test section with a circular coolant channel bored through the center and (b) a monoblock that is a square cross-section parallelepiped with a circular drilled flow channel along the channel centerline. The theoretical or ideal cylinder-like test section would be a circular cylinder with half (-90 to 90 deg) of its outside boundary subjected to a uniform heat flux and the remaining half insulated. For the monoblock, a uniform heat flux is applied to one of the outside surfaces, and the remaining surfaces are insulated. The outside diameter of the cylinder-like test section is 30.0 mm, and its length is 200.0 mm. The monoblock square is 30.0 mm long. The inside diameter of the flow channel for both types of test sections is 10.0 mm. Water is the coolant. The inlet water temperature can be set at any level in the range from 26.0 to 130.0°C, and the exit pressure can be set at any level in the range from 0.4 to 4.0 MPa. Thermocouples were placed at 48 locations inside the solid cylinder-like or monoblock test section to obtain 3-D wall temperature variations and related local heat flux. Finally, the mass velocity can be set at any level in the range from 0.4 to 10.0 Mg/m2·s for the 10.0-mm-diam channel.