Chinese Experimental Fast Reactor To Air Heat Exchanger Thermal Fluid Dynamics Study

China Experimental Fast Reactor(CEFR) is the first pool-type Liquid Metal Fast Breeder Reactor (LMFBR) of passive decay heat removal by natural convection in the world. The air heat exchanger (AHX) is the important equipment in the decay heat removal system (DHRS) , But it has not been studied in detail by calculating or test up to now. Upon the domestic and foreign status of this issue and the situation of CEFR, the thermal hydraulic behavior by natural convection of AHX is calculated in detail by CFD (computational fluid dynamics) software.To calculate the thermal hydraulic behavior of AHX in the design condition and stand-by condition, the numerical model is set up including both the AHX and chimney of the decay heat removal system, and the CFD technique is used in this paper. It is analyzed of the air velocity and temperature distribution in the AHX, and the distribution proved reasonable. Also the power rejection capability of AHX is obtained varying with the environmental temperature and sodium temperature of AHX.According to the calculation and analysis to the AHX, the flowing results can be concluded:1. The heat of sodium in AHX can be rejected to the environment, the result is in accordance with the design parameter of AHX, and the design parameter of AHX proved to be validity.2. The environmental temperatures play an important role in the power rejection capability of AHX, the lower temperatures of air, the larger power rejection capability of AHX.3. The air velocity and temperature distribution in the AHX demonstrates that the thermal hydraulic behavior in the AHX is very complexity.4. In the stand-by condition, natural convection can be set up by adjusting the outlet damper.Depending on the calculation and analysis to thermal hydraulic behavior of AHX, the design parameter of AHX is checked, the power rejection capability of AHX is validated, At the same time, the calculation method of passive fluid flow and heat transfer is also studied in this paper. The temperature and velocity distribution can be the input data for the structure design, and the result also can be used as a reference for the commissioning of AHX.