空间核反应堆电源闭式Brayton循环热力学分析
Thermodynamic analysis of closed Brayton cycles for space reactor power system

空间核反应堆电源闭式Brayton循环一般采用氦-氙混合气体作为循环工质和反应堆冷却剂，设计者为选择合适的循环工质，需研究氦-氙混合气体配比成分变化对循环效率的影响。该文建立空间核反应堆电源闭式Brayton循环热力学模型，采用Fortran 95编程对其进行热力学分析，从绝热系数、回热器回热度、相对压损系数的变化分析了氦-氙混合气体摩尔质量变化对循环效率的影响。结果表明：绝热系数对循环效率的影响较小；回热器回热度越大，循环效率越高；相对压损系数越大，循环效率越低。由于氦-氙混合气体摩尔质量的增加，会降低空间Brayton循环压气机和透平级数，因此选择使回热器回热度达到最大时的配比成分He-8.6% Xe作为循环工质，在给定循环冷/热端温度为403 K/1 300 K的条件下，可以获得29.18%的循环效率。
Abstract：Helium-xenon mixtures can be used as the cycle working fluid and reactor coolant for space nuclear reactor power (SNRP) systems using a closed Brayton cycle. The cycle designers must know how the components of the helium-xenon mixture affect the net system efficiency to choose the best working fluid. A thermodynamic model is developed with Fortran 95 for the SNRP Brayton cycle to analyze the net system efficiency for various molecular mass mixtures in terms of the adiabatic coefficient, regenerator effectiveness and normalized pressure loss coefficient. The results show that the adiabatic coefficient has little effect on the net system efficiency, while the net system efficiency increases with increasing regenerator effectiveness and decreases with increasing normalized pressure loss coefficient. The compressor and turbine in a space Brayton cycle are smaller with higher molecular mass helium-xenon mixtures, so He-8.6%Xe is chosen as the cycle working fluid with the maximum regenerator effectiveness. For cold and hot sink temperatures of 403 K and 1 300 K, the net system efficiency is 29.18%.