The Cooling Performance Improvement of First Wall Using He/CO₂ Binary Mixtures Gas for CN HCCB TBM

The Helium (He) gas Cooled Ceramic Breeder (HCCB) test blanket module (TBM) is the primary option of the Chinese TBM program. In order to enhance the cooling ability of the first wall (FW) of the HCCB TBM and reduce the circulation power, a binary mixtures gas of He gas and additive CO₂ deserves to be another option for the coolant of the blanket, based on high temperature gas-cooled reactors which are a generation-IV fission reactor concept, when it is reported that forced convective heat transfer can be enhanced by means of binary mixing with unreactive gas (e.g., CO₂, molecular weight 44). This technique can significantly enhance the plant’s overall efficiency and reduce the cost of electricity. In order to evaluate the cooling performance of the He/CO₂ binary mixtures gas and its circulation power in the FW of the HCCB TBM, a three-dimensional computational fluid dynamics (CFD) numerical simulation, combined experimental research method is applied. The results reveal that under the condition of the cooling requirements of the FW (e. g., maximum temperature, radial temperature gradient) similar to the pure He gas, the flow velocity and circulation power of the He/CO₂ binary mixtures gas (mole fraction 0.4) are reduced by 70% and 87%, respectively. It implies that the thermal efficiency of a He-cooled blanket system can be fairly enhanced by means of this technique. In the near future experiment plan, it should be tested to validate the correlative cooling scheme of the HCCB TBM, in which the pure He gas and He/CO₂ binary mixtures gas are used as coolant, respectively, at our High-Pressure Helium-Cooled Loop facility. The CFD numerical results will be selected as the reference for the experiments. A new approach may be provided for cooling the high heat flux components of a fusion reactor.