Effect of induced vortex and configuration layout on heat transfer enhancement of helium-xenon mixture

Abstract

The helium-xenon mixture with great heat transfer and compression performance is a marvelous choice as the coolant for the gas-cooled reactor combined with the closed Brayton cycle, which has wide application prospects in the exploration of deep space. However, due to the weight and volume limit for the space nuclear reactor, it is necessary to promote the performance of the heat exchanger significantly for further deeper space exploration missions or more lightweight compact heat exchanger loadings. Therefore, the influence of three kinds of internal novel vortex generators including the Rectangular ring rib, the Kagome lattice, and the Body-Centered Cubic (BCC) lattice on heat transfer enhancement of helium-xenon mixture has been investigated numerically. The results showed that the induced vortex system significantly promoted the heat transfer capability and enhanced the overall Nusselt number up to around 2.6 times that of the smooth tube with the acceptable pressure drop. Moreover, the configuration effects showed that, as the number of vortex generators grew, the overall Nusselt number increased with the increasing friction factor. However, the thermal efficiency index did not change monotonically with the number of vortex generators. The Rectangular ring rib performed best in heat transfer enhancement, but it also caused the greatest pressure drop, while considering the tradeoff between the pressure drop and the heat transfer enhancement, the BCC lattice array showed the best thermal efficiency.