Prediction of Temperature Rise in Water-Cooling DC Busbar Through Coupled Force and Natural Convection Thermal-Fluid Analysis

This paper describes the coupled force and natural convection analysis technique to calculate the increase in temperature of the international thermonuclear experimental reactor poloidal field converter water-cooling dc busbar. The increase in temperature of the busbar is due to Joule's losses and heat dissipation by cooling water and air convection. Joule's loss is calculated by the 3-D eddy-current field analysis and used as the input for the thermal fluid analysis. Energy conservation equation is coded and the primary natural convection coefficient on the external surface of the dc busbar is calculated. An interactive procedure is proposed to predict the busbar operation behavior. Two sets of computational fluid dynamics analysis are presented to calculate the temperature distribution of the dc busbar, cooling water, and air. One is to solve the force convection heat transfer problem inside the busbar cooling water channel with the primary equivalent natural convection coefficient calculated in energy conservation equation. The other is to solve the natural convection behavior on the dc busbar external wall with the equivalent force convection coefficient on the busbar internal cooling channel. The final temperature distribution result is determined by the two heat convection coefficient difference between these two simulations. The accuracy of the technique developed is verified by comparing the measured and the simulated temperature in a prototype thermal test, which proves the high efficiency and accuracy of the proposed approach in the design of water-cooling dc busbar.