Speaker
Description
Helium cooled First wall (FW) is being developed within the breeding blanket (BB) workpackage of the EUROfusion project as one of FW options for the European DEMO. The helium cooling system has to be adapted to high thermal loads and at the same time to achieve reasonable hydraulic parameters. Moreover, different values of the heat fluxes are expected at the DEMO FW depending on the position inside the tokamak. While the most of the FW can be cooled with bare helium ducts, which can be relatively easily characterized by available computational models and correlations, implementation of measures for heat transfer intensification at locations with higher heat fluxes is necessary. The present work deals with one of the possibilities for the heat transfer enhancement which is an application of fins on the channels surface. A RANS (Reynolds-averaged Navier-Stokes equations) CFD model was developed using ANSYS FLUENT CFD code as an option for simulation of this component. The model was benchmarked on the HETREX experimental data considering a DEMO relevant thermal hydraulic conditions and then applied on the full scale computational model of one segment of the Helium Cooled Lithium Lead (HCLL) BB FW. Results of the comparison with the experimental data along with evaluation of the model applicability are reported in the paper. Evaluation of efficiency of selected fins layout in terms of heat transfer for the HCLL conditions and assuming peaking heat fluxes was also performed. Apart from this, the main challenges and recommendations for the computational mesh preparation and numerical solver settings learned from the model development phase are also mentioned. Even though the RANS models cannot affect all physical phenomena, they have some advantages over the other computational methods and can be a useful tool for specific kinds of design and safety studies of the helium cooled FW.
