An experimental and numerical study of flow and heat transfer in helium cooled divertor finger mock-up with sectorial extended surface

Abstract

A jet impingement technique with a sectorial extended surface (SES) concept for the modular helium-cooled divertor has been studied within the framework of the post ITER tokamak, at the Institute for plasma research (IPR), INDIA. Experimental and numerical studies have been conducted to predict the thermal hydraulic performance of a finger type divertor design with proposed SES. Critical thermal hydraulic parameters, effective heat transfer coefficient and pressure loss have been measured in the experiment for the reference divertor as well as for a divertor with SES. The experimental mock-ups are made to full scale respecting Reynolds and Prandtl number similarities. Air is used as the simulant to represent helium, which is used as the coolant in prototype. A novel heat concentrator has been developed to simulate the high heat flux, by electrical heating. The benchmark experimental data have been used to validate the three dimensional conjugate heat transfer models. The computational result for heat transfer coefficients and pressure loss are in satisfactory agreement with the experimental results. Based on detailed parametric studies, correlations have been proposed for Nusselt number and pressure loss coefficient as a function of Reynolds number which can be used for design applications. The proposed SES divertor is seen to significantly augment the thermal performance of the finger type divertor at the penalty of a minimum pressure drop at the prototypical condition. The results of the present study provide added confidence in the numerical model used to design the divertor and its applicability to other high heat flux gas cooled components.