基于运行状态的氦氙布雷顿循环气体组分分析

Gas composition analysis of helium-xenon Brayton cycle based on operating status

氦氙气体的组分保持是氦氙布雷顿能量转换系统长期稳定运行的基础,而无论是工质气体的泄漏还是充填量的调节都有可能导致系统中的氦氙气体组分发生变化,进而影响系统运行状态。通过对氦氙布雷顿系统的动态仿真计算,得到了气体组分发生变化时系统运行的差异。当气体组分发生变化时,系统共同工作线将发生偏移,尤其是气体摩尔质量变小时,共同工作线向喘振线偏移;并且在到达满功率输出时,压气机喘振裕度变小,且需要更高的涡轮入口温度;同时会导致回热器热侧温度入口提高,不利于系统的稳定运行。基于系统仿真结果提出了在额定转速下以负荷率、流量为变量的氦氙气体组分计算方法,为实现氦氙布雷顿循环工质组分变化的监控和调节提出了新思路。该方法中,流量的精确测量是提高组分分析精度的重要保障。

Gas composition maintenance of helium-xenon mixture is the basis for the long-term stable operation of the helium-xenon brayton energy conversion system.However,composition of the helium-xenon gas in the system may change because of working gas leakage or adjustment of filling amount,and then system operation status is affected.Through the dynamic simulation of the helium-xenon brayton system,the difference of the system operation status was obtained with the condition of the gas composition changing.When the gas composition changes,the common working line of the system will shift,especially when the gas molar mass becomes smaller,the common working line will shift to compressor surge line;and when the full power output is reached,the surge margin of the compressor will be smaller and higher inlet temperature of turbine and recuperator is required,which is not conducive to the stable operation of the system.Based on the system simulation results,this paper proposed a calculation method of helium-xenon gas composition with load rate and flow rate as variables at rated speed and put forward a new idea for monitoring and adjusting the change of working fluid composition in helium-xenon Brayton cycle.In this method,accurate measurement of flow rate is an important guarantee to improve the precision of component analysis.