Thermal Fluid Finite Element Calculations for the European PPCS Divertor Concepts

As part of the European Power Plant Conceptual Study, two different divertor designs were proposed, based on previous work on HETS (High Efficiency Thermal Shield) performed at FZK and ENEA. The coolant is helium gas at pressures in the range 10-14 MPa and the inlet temperatures are in the range of 500-800°C. The geometrical complexity of the designs made prediction of heat transfer coefficients, needed for conducting thermal and structural analysis, difficult, and the calculated values from empirical correlations uncertain. This paper presents and summarises results of thermal-fluid calculations performed on both divertor concepts and gives estimates of effective values of heat transfer coefficients based on the local flow conditions and temperature distributions. The agreement of calculations with experimental values for similar conditions, inspires confidence in results from such calculations, and demonstrates that computational fluid dynamic finite element codes can accurately predict behaviour, and can be used to optimise the designs.