Megawatt-level nuclear reactor combined with helium-xenon Brayton cycle system can effectively meet the energy needs of large-scale deep space explorers, satellite base, deep-sea unmanned underwater vehicle and other special energy power equipment for high power, small size, highly reliable power supply, which has wide application foreground and research necessity. Currently, the study of the physical properties of helium-xenon gas mixtures in non-ideal state is not sufficient.

This study aims to establish the thermophysical property model and the thermodynamic model of helium-xenon Brayton cycle, and analyze the effect of the non-ideal gas characteristics to the thermal performance of the cycle.

The second or third order virial expansion was adopted to construct the helium-xenon mixture physical property model to reflect the deviation caused by the non-ideal gas characteristics. The thermodynamic models of turbine, compressor, mixing chamber, and heat exchanger were conducted on the basis of thermophysical property model. Then, the function models of efficiency and specific work were derived from the thermodynamic models of the above main components, and verified by the submerged subcritical safe space reactor (S4) design. Finally, the influence of the thermophysical properties of helium-xenon mixture on thermal performance of helium-xenon Brayton cycle system such as adiabatic coefficient, pressure loss and relative convective heat transfer coefficient at different temperature, pressure and molar fraction of helium was analyzed, and the influence of He-Xe mixing ratio on the He-Xe thermophysical property under different temperature and pressure was explored.

The second or third order virial expansion was adopted to construct the helium-xenon mixture physical property model to reflect the deviation caused by the non-ideal gas characteristics. The thermodynamic models of turbine, compressor, mixing chamber, and heat exchanger were conducted on the basis of thermophysical property model. Then, the function models of efficiency and specific work were derived from the thermodynamic models of the above main components, and verified by the submerged subcritical safe space reactor (S4) design. Finally, the influence of the thermophysical properties of helium-xenon mixture on thermal performance of helium-xenon Brayton cycle system such as adiabatic coefficient, pressure loss and relative convective heat transfer coefficient at different temperature, pressure and molar fraction of helium was analyzed, and the influence of He-Xe mixing ratio on the He-Xe thermophysical property under different temperature and pressure was explored.

The proposed model can accurately calculate the thermophysical properties of the He-Xe mixture, including density, specific heat capacity, viscosity, thermal conductivity and Prandtl number can be accurately calculated by the proposed model under different helium molar fraction. The model proposed in this work can be applied to the design and optimization of the He-Xe Brayton cycle systems and direct the device selection of the He-Xe Brayton cycle system.