The influence of turbulators on the flow and heat transfer characteristic of helium-xenon mixture inside the tight lattice rod bundles

Abstract

The gas-cooled nuclear reactor combined with the closed Brayton cycle is the ideal choice for future high-power space missions. The helium-xenon mixture is a suitable working medium for the reactor due to its good compressibility and heat transfer capacity. For the further development and application of a more lightweight compact reactor, the influence mechanism of turbulator structures with different angles and layouts on the heat transfer enhancement of a helium-xenon mixture in the sub-channel of a gas-cooled nuclear reactor is numerically studied. The results show that the heat transfer is effectively enhanced due to the vortex and secondary flow induced by the turbulator, leading to periodic fluctuations in the Nusselt number. When comparing the results at different angles, it is observed that the heat transfer enhancement from the turbulator at a 90° angle is relatively small, while the pressure drop is significant. Due to the secondary flow in a narrow triangular space induced by a turbulator with a 45° angle, the mixing between high and low-temperature fluids is effectively enhanced, leading to a more significant improvement in heat transfer. The heat transfer performance and thermal efficiency index of different turbulator layouts are summarized and compared, providing a reference for the heat transfer design of gas-cooled nuclear reactors.