Heat transfer analysis of tokamak in-vessel coil water-cooling channel joint

Abstract A certain number of the Tokamak in-vessel coil joints are designed for avoiding assembly difficulties and limiting conductor cost. Long water-cooling channel joints with different deflectors were studied basing on the computational fluid dynamics (CFD), and experimental campaigns and the analysis results indicate that the implementation of a series of deflectors can effectively contribute to promote heat absorption by cooling water. This evidence can furtherly contribute to a safe disposal of the heat deposited during plasma disruption scenarios by Tokamak in-vessel coil. The Nusselt numbers characterizing the water-cooling channel joint has proved to decrease along with the increase of the deflector curvature radius, and, eventually, the deflector with small curvature radius revealed to be more suitable in terms of enhanced heat transfer capacity. This reveals a further advantage due to the limited joint space, which can be dedicated to accommodate the deflectors; the smaller is the curvature radius the larger number of these devices can be implemented inside the joint. In addition, the results obtained during the heat transfer experimental campaign are in good agreement with the numeric simulation results. From these tests a heat transfer function of long-curved water-cooling channel joint with smaller curvature radius deflectors is proposed and obtained, and exploited as a starting point to further study heat dissipation mechanism on similar components.