Enhanced Surface Heat Removal Using a Porous Tungsten Heat Exchanger

A novel concept for drastically improving the surface heat load capability of helium-cooled tungsten-alloy tubes is being developed for plasma facing components. The concept utilizes ultra-low density (90% porosity) W-foam, which is chemical-vapor-deposited inside a W-tube. The W-foam enhances the effective heat transfer coefficient inside the tube by significantly increasing the conduction path from the wall to the coolant fluid. A mockup of the W-tube/W-foam system has been constructed for testing at the helium loop and electron beam facility at Sandia National Laboratories, Albuquerque, NM. A finite element model (FEM) was constructed based on a 3-D solid model of the test section. The enhanced heat transfer coefficient was determined based on fundamental heat transfer principles through porous media. The porous tungsten heat exchanger tube exhibits a 3 fold improved surface heat load capability relative to a plain W-tube at temperatures above 1200°C.