【作者】 刘惠民；

【导师】 陈安斌；

【作者基本信息】 哈尔滨工业大学 ， 制冷与低温工程， 2006， 硕士

【摘要】 本文以中国原子能科学研究院HI-13串列式加速器升级工程项目中采用的四分之一波长腔(Quarter Wave Resonator—QWR)超导腔恒温柜系统为研究对象。研究了恒温柜系统在低温下的若干问题,包括恒温柜系统热负载计算、低温冷却流程的模拟分析以及用FLUENT和ANSYS对恒温柜内关键设备的温度场进行了模拟。目的是为QWR超导腔恒温柜在低温下正常工作提供设计保障。本文在详细描述恒温柜冷却系统的基础上,详细计算了4.2K冷质量与77K冷屏的辐射漏热,同时,还对恒温柜内部支撑系统计算了变物性下的导热漏热,得出了恒温柜系统的静态和动态热负荷分别为4.692W和38.4W,并分析比较了液氮冷屏采用夹层冷却方式与铜管缠绕冷却方式的优缺点,为流程模拟的参数确定提供了依据。确定了系统中各主要设备的关键热力参数,同时计算了冷却QWR到4.2K需要的液氦量以及其冷却时间。采用恒温柜并联的冷却方式对系统建立了数学计算模型,选用了返回氦气经控制杜瓦冷却后再进入制冷机末级换热器冷端的方案,并结合超导腔对压力和温度的要求,用大型流程软件计算出了超导腔低温系统正常运行时所需的最佳氦流质量流量为31.57 g/s,允许质量流量波动范围为±3 g/s。同时讨论了氦流质量流量过小时对系统稳定性的影响。用FLUENT数值模拟了QWR超导腔正常工作时的温度分布情况,得到其表面的最大温差,用以指导冷却系统的设计,保证超导腔的正常工作。模拟比较了液氮冷屏在采用螺旋管和蛇形管两种冷却方式情况下屏上温度分布,为冷屏冷却管线布置的选择提供理论依据。用有限元软件ANSYS模拟了4.2K冷质量支撑件的温度分布情况,同时得到了其导热漏热,并与理论计算进行了比较。更多还原

【Abstract】 The dissertation focuses on study on the QWR cryogenic system, which is the key component of the Tandem Superconducting Device(TDS) in HI-13 Upgrade in China Institute of Atomic Energy. The study will serve as the guideline for the engineering design of the TDS QWR cryogenic system.Detailed calculations of the radiant heat loads to 4.2K cold mass and 77K heat shield were carried out based on the structure of the QWR cryostat. The conductive heat loads from the supports inside the cryostat were given with variable physical properties of materials. The total static loads and dynamic loads are summed as 4.692W and 38.4W, respectively. And comparison between the double-wall cooling method and the cooling tube method for the 77 heat shield has been discussed to provide the thermal parameters for flow process simulation.The critical thermal parameters of the main components of the QWR cooling system were determined for parallel arranged QWR cryostats. The mass flow and time for cool-down of the QWR to 4.2K was also estimated. Numerical model for the cooling process has been developed in case that the QWR cryostats are connected in parallel. Temperature at the outlet of QWR cooling channel and its pressure fluctuation were calculated with the change of the mass flow of He by the large-scale process software. The optimized mass flow of He and the allowed fluctuation range were also obtained according to the temperature and pressure required by the QWR superconducting cavity. And the influence on the system when the mass flow of He is far from normal has been discussed.The temperature distribution of QWR has been numerically simulated by FLUENT and the maximal temperature difference has been obtained. The detailed simulation and comparison of the heat shield has been carried out for the spiral cooling method and the flexible cooling method. The temperature distribution of the support for the 4.2K cold mass has been simulated by ANSYS, and its heat flux has been simulated and compared with the theoretical results presented preciously.更多还原