氦-氙混合气体物性对布雷顿循环影响分析

将对应态原理用于Chapman-Enskog理论修正，得到的半经验公式可较好地预测二元惰性混合气体物性。采用Fortran 95开发了氦-氙混合气体物性计算程序，分析了氦-氙混合气体物性随摩尔质量、温度、压力的变化关系。在此基础上分析了物性变化对空间布雷顿循环的绝热系数、对流换热性能、阻力特性的影响。结果表明：压力为2.0 MPa、温度为400 K时，随着摩尔质量的增加，氦-氙混合气体的绝热系数由0.40（纯氦气）增加到0.44（纯氙气）；混合气体相对于纯氦气的相对对流换热系数随摩尔质量的增加呈先增大后减小的趋势，在15 g/mol附近取得极大值；相对压损系数则随摩尔质量的增加单调递增。分析结果可为氦-氙混合气体在空间核反应堆电源中的应用提供设计依据。     

基于RELAP5的氦氙流动换热计算模块开发与验证

反应堆热工系统分析程序是开展热工水力计算与安全评价的重要工具。为开发适用于氦氙气冷空间堆的热工系统分析程序,本文在RELAP5/MOD40程序中拓展了氦氙混合气体（He Xe）物性计算模块,添加了适用于He Xe的传热关系式,将拓展后程序计算值与实验值进行对比。结果表明：程序默认的Sutherlands定律用于He Xe物性计算时将引入较大误差;Dittus Bolter公式对He Xe对流换热时的Nu预测偏高,将导致不保守的壁温计算结果。拓展后的程序对He Xe压降和换热计算结果均与实验值吻合较好,验证了程序开发的正确性以及程序用于He Xe流动换热计算的功能。本研究可为系统层面程序开发奠定基础。     

棱柱式高温气冷空间核反应堆初步方案设计与中子物理分析

空间核反应堆电源将核裂变能转换为电能,与太阳能、化学燃料电池等其他形式的电源相比,具有电功率大、系统比功率高、使用寿命长等优点,在太空探索中具有广阔的应用前景。以高温气冷堆技术为基础,提出了以氦氙混合气体作冷却剂,直接布雷顿循环的空间核反应堆电源方案。核反应堆是采用包覆颗粒燃料的小型棱柱式高温气冷堆,热功率为5 MW。采用蒙特卡罗方法进行了中子物理分析。结果表明,设计的反应堆满足10a以上的满功率运行寿期,具有负的反应性温度系数。通过布置B4C安全棒,使反应堆在发射失败引起的堆芯进水事故中能保证次临界。     

氦-氙混合气体动力粘度测量

针对氦-氙混合气体热物性参数的研究匮乏问题,对氦-氙混合气体的粘度进行了研究。基于双毛细管法设计实验装置,并考虑了修正项;采用氩气对实验装置进行标定后,测量了2种氦-氙混合气体（15、40 g/mol）在温度298.15~548.15 K、压力0.1~2.5 MPa下的动力粘度,并对测量结果进行了评价;为得到氦-氙混合气体高温下粘度,采用拟合粘度关系式的方法将粘度拟合值外推至温度为1273 K的粘度值。结果表明,本文实验结果与文献值符合较好;实验装置测量合成标准不确定度为3.88%,拟合值与文献值（实验值、计算值）的偏差较小。本研究为空间气冷堆设计和优化提供了基础热物性参数。      

兆瓦级空间热管反应堆动力系统概念设计

针对目前航天技术发展对动力提出的要求,参考国外提出的空间核动力系统设计,提出了新型兆瓦级空间热管反应堆核动力系统概念设计。堆芯为金属锂热管冷却、石墨慢化热中子反应堆,采用转鼓控制反应性,堆芯热量通过热管导出。与国外热管反应堆设计方案中燃料棒与热管相间布置方案不同,本文采用了热管-燃料复合元件,即燃料包裹于热管外壁面。能量转换采用以氦氙混合气体为工质的布雷顿动态热电转换。系统废热通过钠钾合金冷却回路传递到钾热管辐射板,通过辐射换热释放入太空。对热管反应堆堆芯物理及热工进行了初步分析,并对热管辐射板进行了性能分析,结果表明,所设计热管反应堆堆芯在设计功率下满足相应安全性要求,同时热管辐射板具有足够的能力将系统废热导出。     

小型氦氙冷却反应堆事故发生频率分析研究

氦氙冷却反应堆可采用一体化布雷顿循环系统，在小型化、轻量化方面具有独特优势而备受关注。但目前鲜有关于小型氦氙冷却反应堆的严重事故分析研究。概率安全评价法（Probabilistic Safety Assessment,PSA）是一种评价反应堆安全性的重要方法，可为反应堆设计改进、故障诊断、运行指导等提供有价值的依据。而始发事件发生频率是PSA分析所必需的输入参数。本文以小型氦氙冷却移动式固体核反应堆电源为分析模型，参考高温气冷堆以及压水堆运行经验及部件失效数据，分析了堆芯排热增减、反应性和功率分布异常、管道破口和设备泄漏异常、未能紧急停堆的预期瞬态（Anticipated Transient Without Scram,ATWS）以及丧失场外电源等事故的发生频率，结果分别为3.90×10^-2RY^-1、2.36×10^-1RY^-1、2.69×10^-2RY^-1、6.50×10^-2RY^-1、2.69×10^-2<...     

直接布雷顿循环气冷反应堆系统运行特性分析

基于Matlab/simulink程序,针对小型直接布雷顿循环反应堆系统,通过模块化思想建立该系统数学物理模型,开发了系统分析程序。通过改变反应堆、透平、压缩机、换热器等关键设备的运行参数或引入阶跃扰动,模拟了系统稳态工况与瞬态变工况运行,得到了关键设备功率、进出口压力、温度等关键参数的变化曲线。结果表明,系统分析程序对小型直接布雷顿循环反应堆系统稳态与瞬态运行特性的模拟结果较合理,能为小型直接布雷顿循环反应堆系统的设计、优化与安全分析提供依据。     

直接布雷顿循环气冷反应堆系统运行特性分析

基于Matlab/simulink程序，针对小型直接布雷顿循环反应堆系统，通过模块化思想建立该系统数学物理模型，开发了系统分析程序。通过改变反应堆、透平、压缩机、换热器等关键设备的运行参数或引入阶跃扰动，模拟了系统稳态工况与瞬态变工况运行，得到了关键设备功率、进出口压力、温度等关键参数的变化曲线。结果表明，系统分析程序对小型直接布雷顿循环反应堆系统稳态与瞬态运行特性的模拟结果较合理，能为小型直接布雷顿循环反应堆系统的设计、优化与安全分析提供依据。     

空间反应堆布雷顿循环热力学优化分析

闭式布雷顿循环具有高效率与高能量密度,适用于空间核反应堆的能量转换系统。出于经济性的考虑,地面大型高温气冷堆的布雷顿循环能量转换系统均采用效率最高的运行模式;而在空间反应堆能源中,系统受到体积、质量与特殊运行环境的限制,故提出另一种优化模式——循环比功最高优化。本文就空间反应堆闭式布雷顿循环进行优化分析,利用Fortran语言对两种优化模式进行热力学分析对比,为空间反应堆的设计计算提供参考和基础。结果表明:新提出的循环比功优化在降低空间布雷顿循环方面较有优势,但会造成叶轮机械设计难度的增加。最终设计方案的选取可根据工程要求在两种优化模式中进行折中选择。     

HTR-10主氦风机停止试验的模拟

10MW高温气冷实验堆(HTR-10)是我国第1座模块式高温气冷堆。主氦风机停止试验是HTR-10的调试试验之一,该试验不仅证明了丧失强迫循环冷却时反应堆的安全性,也为系统分析程序的验证提供了实测数据。基于实际的试验工况,利用THERMIX程序对主氦风机停止试验进行了模拟,分析了反应堆主要参数的变化。对于反应堆功率,计算结果与试验结果符合得很好,证明了程序的正确性、合理性和适用性。试验过程中,燃料元件中心最高温度始终低于1 230℃的温度限值。     

Off-design performance research of an axial helium compressor for HTGR-10 power conversion unit

Helium compressor is a determining part of the power conversion unit (PCU) which is used in high-temperature gas cooled reactor (HTGR). A direct Helium Brayton cycle is applied to the PCU system for the power conversion. In order to optimize the compressor design, a performance test about helium compressor is given out to verify the CFD results. Also because of the strong relevancy between helium compressor and the other parts of the PCU system, it is quite important for designers to evaluate the performance of a helium compressor in different operational states. Tests have been carried out in different operating conditions and the compressor performance characteristics were obtained. Numerical simulation could help to further the understanding the details of compressor's flow channel and blades. Meanwhile, an economic method with air as the working fluid to perform the aerodynamic design and optimization of helium compressor is obtained. The experimental results showed that as long as the air flow conditions are correctly selected, the aerodynamic design of air compressor will be a valuable reference for the design of helium compressor.     

兆瓦级核电推进系统布雷顿循环热电转换特性分析

闭式布雷顿循环是兆瓦级核电推进系统主要采用的动态热电转换方式，具有结构简单、转换效率高等特点。本文针对兆瓦级核电推进系统的动态布雷顿热电转换方式进行特性分析，具体内容包括：对氦气、氮气、二氧化碳和氙气4种工质及它们以不同比例混合的工质的热物性进行比较，进而对其在兆瓦级核电推进系统闭式布雷顿循环中的换热性能、压力损失系数和透平机械所需级数进行分析；以带有同流换热器和预冷器的直接气体透平循环为研究对象，比较兆瓦级核电推进系统气体透平循环在采用不同比例混合物作为工质时的循环效率，并对参数变化对循环效率的影响进行研究。本研究为兆瓦级核电推进系统气体透平循环在工质选择方面提供了一定的参考，为其设计和控制系统的研究奠定了基础，为以后进行气体透平循环动态性能研究打下了基础。     

Parametric studies on different gas turbine cycles for a high temperature gas-cooled reactor

The high temperature gas-cooled reactor (HTGR) coupled with turbine cycle is considered as one of the leading candidates for future nuclear power plants. In this paper, the various types of HTGR gas turbine cycles are concluded as three typical cycles of direct cycle, closed indirect cycle and open indirect cycle. Furthermore they are theoretically converted to three Brayton cycles of helium, nitrogen and air. Those three types of Brayton cycles are thermodynamically analyzed and optimized. The results show that the variety of gas affects the cycle pressure ratio more significantly than other cycle parameters, however, the optimized cycle efficiencies of the three Brayton cycles are almost the same. In addition, the turbomachines which are required for the three optimized Brayton cycles are aerodynamically analyzed and compared and their fundamental characteristics are obtained. Helium turbocompressor has lower stage pressure ratio and more stage number than those for nitrogen and air machines, while helium and nitrogen turbocompressors have shorter blade length than that for air machine.     

Performance analyses of VHTR plants with direct and indirect closed Brayton cycles and different working fluids

This paper investigated the performance of Very High Temperature Reactor (VHTR) power plants with helium working fluid and direct and indirect Closed Brayton Cycles (CBCs), and with binary mixture working fluids of He–Xe and He–N₂ (molecular weight of 15 g/mole) and indirect CBCs. Also investigated are the effects of using low- and high-pressure compressors with intercooling, versus a single compressor, using bleed cooling the reactor pressure vessel in direct CBC helium plants, and varying the reactor exit temperature from 700 °C to 950 °C on the plant thermal efficiency, cycle pressure ratio and the size of and number of stages in the turbine and compressor. Analyses are performed for a shaft rotation speed of 3000 rpm, reactor thermal power of 600 MW and a temperature pinch of 50 °C in the intermediate heat exchanger (IHX) for the indirect CBCs.     

Evaluation of alternate power conversion unit designs for the GT-MHR

General Atomics in the USA and Experimental Design Bureau of Machine Building (OKBM) in the Russian Federation have jointly developed a nuclear power plant design, the gas turbine modular helium reactor (GT-MHR). There have been considerable improvements during the last 10 years, which resulted in a more effective, efficient and safe design. The existing design is based on a 600 MW(t) reactor cooled by helium at a pressure of about 7 MPa. The power conversion unit (PCU) uses reactor outlet helium with a temperature of 850 °C in a direct Brayton cycle to achieve the cycle efficiency of about 48%. The PCU consists of a gas turbine, a recuperator, a precooler, low-pressure and high-pressure compressors, an intercooler, and a generator. The turbomachine (TM) includes the turbine, compressors and generator mounted on a single vertical shaft. TM shaft rotation speed is 4400 rpm. The shaft of generator is connected to the turbine shaft by a flexible coupling. The required grid frequency of generated electricity is achieved by a converter. All PCU components are enclosed in a single vessel. TM uses radial and axial electromagnetic bearings (EMB) for support. Catcher bearings (CB) are provided as redundant support for the TM rotor in case of EMBs failure. Several alternative PCU designs were analyzed on the basis of current progress in technologies, new world experience, and experience accumulated in the process of GT-MHR design development. Results of these analyses will be taken into account when a final PCU design is selected.     

Multiple reheat helium Brayton cycles for sodium cooled fast reactors

Sodium cooled fast reactors (SFR) traditionally adopt the steam Rankine cycle for power conversion. The resulting potential for water–sodium reaction remains a continuing concern which at least partly delays the SFR technology commercialization and is a contributor to higher capital cost. Supercritical CO₂ provides an alternative, but is also capable of sustaining energetic chemical reactions with sodium. Recent development of advanced inert-gas Brayton cycles could potentially solve this compatibility issue, increase thermal efficiency, and bring down the capital cost sufficiently to compete directly with light water reactors. In this paper, helium Brayton cycles with multiple reheat and intercooling states are presented for SFRs with reactor outlet temperatures in the range of 510–650 °C. The resulting thermal efficiencies range from 39% to 47%, which is comparable with supercritical recompression CO₂ cycles (SCO2 cycle). A systematic comparison between the multiple reheat helium Brayton cycle and the SCO2 cycle is given, considering compatibility issues, plant site cooling temperature effect on plant efficiency, full plant cost optimization, and other important factors. The study indicates that the multiple reheat helium cycle is the preferred choice over SCO2 cycle for sodium cooled fast reactors.     

小型氟盐冷却高温堆耦合布雷顿循环系统分析与研究

为满足小型氟盐冷却高温堆（FHR）能量转换需求,开发与之匹配的高效、紧凑、无水冷却动力转换系统,本文对比了超临界二氧化碳（SCO₂）、空气、氩气（Ar）、氮气（N₂）、氙气（Xe）5种气体工质在不同布雷顿循环构型中的热电转换效率、?效率、?损失分布。研究发现,SCO₂布雷顿循环相比其它工质循环具有最高的热电转换效率和?效率,且结构更为紧凑,易于小型化和模块化,与小型氟盐冷却高温堆耦合更具优势;进而对SCO₂布雷顿循环进行构型优化,得出匹配小型氟盐冷却高温堆的最佳循环构型方式,构成固有安全模块化小型氟盐冷却高温堆热电转换系统,为西部能源利用提供新研究思路。      

商用高温气冷堆联合循环方案研究

本文针对高温气冷堆动力转换单元设计了3种联合循环方案,并将3种循环方案在反应堆出口温度900℃的情况下与闭式Brayton循环进行比较。结果表明:闭式Brayton循环在反应堆出口温度较高时,相应反应堆入口温度也较高,这受到反应堆压力壳材料限制,且所需压气机压比较大;联合循环方案的反应堆入口温度低于370℃,反应堆压力壳可使用SA533钢材,无需内壁冷却,且所需压气机压比较小。方案比较显示,提高联合循环效率需增加下位循环出力。方案3的上位循环是简单Brayton循环,下位循环是再热Rankine循环,循环效率可达50.1%。