3D CFD analysis of subcooled flow boiling heat transfer with hypervapotron configurations for ITER first wall designs

The need of a high performance CFD simulation to evaluate design accuracies involving subcooled boiling as a local high heat removal scheme makes the use of two-phase flow simulation challenging. This paper addresses the applicability of Bergles and Rosenow nucleate boiling model and Reynolds Averaged Navier Stokes (RANS) methods to ITER FW CFD/thermo-fluid design analysis, in which subcooled boiling in a hypervapotron is considered for the high heat flux removal. Initially, the subcooled flow boiling model adopted in the considered CFD code is evaluated by comparing the calculated wall temperatures with the estimated values that were derived from the empirical correlations. The geometry, volumetric flow rate, and the surface heat flux influence upon the heat transfer enhancement and the predicted wall temperature were then explored and discussed. In the subsequent thermo-fluid design analysis, a complete FW panel subjected to a local high heat flux of 5 MW/m2 was analyzed.