CFETR极向场磁体馈线系统线圈终端盒初步设计与分析

介绍了中国聚变工程实验堆(CFETR)极向场线圈馈线系统终端盒(CTB)设计,CTB由外盒体、80K内冷屏、电流引线及超导母线、内部管路系统、阀门系统等子部件组成.利用ANSYS有限元软件,在运行工况和地震工况下对CTB外盒体及内冷屏进行结构强度校核、结构热分析和地震响应分析,得到CTB外盒体的位移、应力分布云图和在地...     

ITER装置CTB盒冷屏绝热结构初步设计与分析

根据装置系统对CTB盒的绝热性能要求,文章对CTB盒的真空绝热层的选型、搭接处理和真空度保证措施进行了分析和设计,并分别对辐射传热、固体导热、气体导热的表观传热系数,和绝热结构总的热损失进行了数值计算。经初步检验,该绝热结构的设计是可信的,并且其总的热损失能够满足ITER设计文集的要求,为CTB盒内部冷屏的设计和制造提供了可靠的技术参数。     

μ子源超导俘获线圈测试杜瓦设计与校核

根据高μ子源超导俘获线圈整体测试系统的要求,设计了μ子源超导俘获线圈测试杜瓦系统.包含液氦杜瓦、真空杜瓦及绝热冷屏,采用Solidworks软件对测试杜瓦系统进行3D建模.通过对绝热冷屏统进行了详细的传热学计算,绝热冷屏的可以满足μ子源超导俘获线圈测试过程的漏热需求;根据μ子源超导俘获线圈测试实际工况,对真空杜瓦和液氦杜瓦进行了Ansys有限元软件分析与校核,得到杜瓦详细的应力及变形结果,分析表明,测试杜瓦的设计较为合理,可以作为工程设计的理论计算依据     

EAST超导托卡马克冷屏结构与受力分析

EAST是一个全超导磁体系统的托卡马克实验装置,超导纵场和极向场磁体工作在4K温区下。在磁 体和其它发热部件之间布置有冷屏系统,以减少作用到所有低温冷质部件上的热载,将其保持在最低水平。该系 统包括真空室冷屏(内冷屏)和外真空杜瓦冷屏(外冷屏)两部分。在分析了冷屏低温运行时所受热应力以及等离 子体破裂时所受电磁载荷的基础上,运用大型有限元分析程序NASTRAN,对其不同载荷状况进行了数值计算,为其 结构设计与优化提供了理论依据。     

热阻对液氮冷屏性能的影响研究

超导元件需用液氦降温至极低工作温度才能实现超导性能,液氦温区仅靠真空多层绝热方式无法达到理想绝热效果,采用液氮冷屏隔断液氦和环境之间的传热,能够有效降低液氦系统蒸发损失和液氦用量。为研究热阻对液氮冷屏传热特性的影响,建立了液氮冷屏热阻模型,通过理论传热计算得到了不同热阻与冷屏板温度及传热量之间的关系,利用数值模拟软件对不同热导率材料和不同板厚下冷屏板的温度分布进行了分析。结果表明,最不利热阻为接触热阻和导热热阻,采用高导热系数材料及适度增加冷屏板厚度有助于提高冷屏板温度分布的均匀性,减小接触热阻和冷屏板表面发射率有助于提高冷屏隔热性能,为改善冷屏热屏蔽效果提供依据。     

小型传导冷却低温系统热分析与实验研究

传导冷却型低温系统中,各结构组件间的热平衡过程是以固体间热传导的形式向制冷机实现热量传递。由于各冷却部件降温条件的差异,会导致系统内部温度分布不均匀,影响被测样品性能测量,需对系统结构开展热分析与实验研究。借助ANSYS软件,建立了小型低温系统三维模型并进行了热分析,结果显示,预期系统最低温度为2.38 K,冷屏最大温差不超过1.0 K,样品台最大温差不超过0.1 K。同时,采用一套2.2 W@4.2 K双级制冷机作为冷源,完成了低温系统降温与精准控温实验。实验结果表明,冷屏误差不超过1.5 K,样品台误差不超过0.01 K,与模拟分析结果吻合良好,满足系统要求,验证了传导冷却低温系统热分析方法的准确性以及实验装置测温的可靠性,为类似装置的热分析及其设计提供了参考。     

低温超导磁体杜瓦装置的结构设计与传热分析

介绍了低温超导磁体杜瓦装置的结构设计和传热分析。为了获得有效的超导磁体运行的低温环境,研制了一套采用真空多层绝热、铜辐射冷屏、蛇形排气管结构形式的绝热系统,省去了传统的在内杜瓦外面添加液氮屏的结构,简化了工艺结构,操作方便,绝热效果良好。通过传热理论计算表明,液氦的损耗量小于技术要求的0.9 L/h指标,能够保证超导磁体系统能够在一定的低温环境下长时间的运行。     

ITER极向场馈线系统冷屏初步设计

ITER极向场馈线系统采用冷屏以降低4K温区低温部件的热负荷。该文对极向场馈线冷屏的初步设计进行介绍,并计算了冷屏的热负荷。     

低温推进剂贮存中SOFI和MLI实验研究

根据低温推进剂长时间在轨贮存的要求,设计并搭建了绝热系统地面验证测试装置,对绝热系统的热力学性能进行测试。针对55L贮箱,采用了泡沫绝热(spray on foam insulation,SOFI)和多层绝热(multilayer insulation,MLI)结合的复合绝热系统,分别在高真空(5×10^-3Pa以上)和大气压条件下进行了验证实验(液氮作为替代工质)。贮箱外绝热系统为15m m厚泡沫绝热层和45组多层绝热时,高真空条件下液氮日蒸发率为0.77%,多层绝热层表观热导率为1.29×10^-4W/(m·K),据此折算为液氧时日蒸发率为0.55%。将高真空和大气压条件下的实验结果比较发现,泡沫绝热层所占热阻分别为总热阻的0.19%和45.14%。     

EAST托卡马克装置外冷屏的热负荷分析

外真空杜瓦冷屏 (简称外冷屏 )是 EAST超导托卡马克核聚变装置的重要部件之一 ,它在处于室温下的外真空杜瓦与运行在 4 .5 K温度下的超导线圈之间形成了一道隔热的屏障 ,以保证装置能够稳定高效的运行。文中运用有限元分析软件 ANSYS对外冷屏封头、中筒、底座的传热情况做了计算与分析 ,以得到在氦气入口处压强为 5 .2 bar,温度为 80 K的情况下 ,外冷屏低温面板的详细设计方案     

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根据ITER装置对CTB盒技术性能的要求,对CTB盒中冷屏的支撑部件进行了结构和传热的分析和设计。对结构形式的选择、结构强度的理论计算和支撑结构总的热损失进行了设计和计算,用ANSYS软件对该结构的非线性接触结构-热耦合问题进行了仿真分析。研究结果表明,球支撑结构既能够满足系统对支撑的结构安全要求,在有压接触情况下的漏热量符合ITER设计文集的规定。     

ITER装置CTB盒体冷屏结构设计与传热性能的数值模拟

为了满足ITER国际组对CTB盒体冷屏的技术要求,论文对其结构型式和传热性能分别进行了设计、选型和数值模拟分析。通过对设计后的冷屏结构进行ANSYS分析,选择了冷屏为3mm厚的3003铝合金材料,确定了冷却管为22mm×22mm-φ18mm外方内圆截面的结构型式,并选择由卡子实现冷却管与冷屏面板的连接固定。最后,利用FLUENT软件针对设计后的冷屏结构进行了流固耦合数值模拟分析,获取了冷屏面板上总体温度的分布情况,验证了论文中选取和设计的冷屏结构型式能够满足ITER国际组设计技术要求,为下一步CTB盒的设计研制提供了技术保证和依据。     

辐射换热对冷冻靶温度影响的数值分析

为了研究辐射换热对惯性约束聚变间接驱动靶系统的温度场影响,建立了带有辐射屏蔽罩的冷冻靶系统数值计算模型,利用FLUENT软件的离散坐标辐射模型分析了系统的辐射换热,并对影响辐射换热的相关结构和参数进行了模拟优化。结果表明:采用双层屏蔽罩、减小屏蔽罩的发射率、增大屏蔽罩的散射分数和金腔的吸收率、增设暴风窗,均可有效减小靶丸与外界的辐射换热,从而改善靶丸表面的温度均匀性。     

Infrared filters for cryogenic millimeterwave receivers

Filters are required to block infrared radiation from the low temperature regions of cryogenic receivers to reduce thermal loading and temperature gradients. The design and analysis of PTFE filters mounted on the radiation shield of a closed-cycle Joule-Thompson 4 K refrigerator is described. Calculations of the thennal transmission and emission of the filters are compared with measurements. It was found that the filters were not as effective as expected since the heat sinking of the material to the radiation shield was poor, but the overall heat load was less than anticipated since a thermal gradient developed across the polystyrene foam vacuum window, reducing its infrared emission.NRAO is operated under co-operative agreement with the National Science Foundation.     

基于ANSYS的传导冷却超导磁体系统的热分析

在传导冷却超导磁体系统中,超导磁体与系统其它部分的温度平衡过程是依靠固体间的热传导来实现热量传递的。由于超导磁体和冷屏等低温部件冷却条件的差异,将导致磁体内部各处和冷屏不同部位的温度分布不均匀。分析研究超导磁体系统的低温温度分布状况,对于低温系统的热设计和磁体的温度裕度设计具有重要意义。文中借助于ANSYS有限元分析软件,建立了一个大口径传导冷却超导磁体低温系统的稳态三维热分析模型,仿真了超导磁体和冷屏的空间温度场,得到了传导冷却超导磁体低温系统的热分布规律。该分析结果对于大口径传导冷却超导磁体的低温系统设计具有重要的参考价值。     

Circular radiation heat shields with temperature dependent emissivities: transient and steady-state analyses

Radiation heat loss is an important type of heat loss in thermal systems. In this work, a numerical study of the transient response of two circular radiation heat shields inserted between two parallel and circular surfaces of emissivities ε₁ and ε₂ is presented. The same dimensions have been assumed for the two main radiating surfaces and the two radiation shields. The radiation shields are assumed to have different emissivities on their top (ε₃ and ε₅) and bottom ( ε₄ and ε₆) surfaces, and both are assumed to be different but linear functions of temperature. A specific configuration is investigated in detail to highlight the transient temperature and heat transfer characteristics of the system. Some new results for the transient temperature and heat transfer characteristics of the system such as the effect of shield location, shield emissivities, the temperature dependence of shield emissivities, system dimensions, temperatures of the hot and cold surfaces and emissivities of the hot and cold surfaces are presented for future references. It has been observed that increasing the temperature of the first radiation shield by changing a parameter such as surface emissivity or distance between the radiation shield or the temperature of the hot surface, will not necessarily decrease the temperature of the second radiation shield.     

Experimental And Analytical Investigation Of Steady-State Thermal Profile Of Forced-Flow Ln2-Cooled Thermal Radiation Shield For Superconducting Linear Accelerator Cryomodule

Acceleration of heavy ions through the superconducting linear accelerator is achieved by superconducting resonators housed in the cryomodules operating at 4.2 K. In the cryomodule, radiation heat flow from the ambient to the 600 kg of cold mass at 4.2 K is thermally screened by the intermediate thermal shield made of copper. The six surfaces of 17 m² total surface area of the box-shaped thermal shield are cooled in series by the forced flow of liquid nitrogen at 3.2 bar absolute pressure. The boiling temperature of liquid nitrogen at 3.2 bar is 90 K. The steady-state temperatures of the different surfaces of the thermal shield are in the range of 96–115 K at 21.25 L/h flow rate. The steady-state thermal profile of the different surfaces of the thermal shield has also been estimated for different flow rates using a simple analytical technique. The analytical thermal profile of the thermal shield has been correlated with the experimental measurement.     

Thermal performance analysis of vacuum variable-temperature blackbody system

In this paper, the design and structure of a vacuum variable-temperature blackbody system were described, and the steady-state thermal analysis of a 3-D blackbody model was presented. Also, the thermal performance of the blackbody was evaluated using an infrared camera system. The blackbody system was constructed to operate under vacuum conditions (2.67 × 10⁻² Pa) to reduce its temperature uncertainty, which can be caused by vapor condensation at low temperatures usually below 273.15 K. A heat sink and heat shield including a cold shield were embedded around the radiator to maintain the heat balance of the blackbody. A simplified 3-D model of the blackbody including a radiator, heat sink, heat shield, cold shield, and heat source was thermophysically evaluated by performing finite elements analysis using the extended Stefan–Boltzmann’s rule, and the infrared radiating performance of the developed system was analyzed using an infrared camera system. On the basis of the results of measurements and simulations, we expect that the suggested blackbody system can serve as a highly stable reference source for the calibration and measurement of infrared optical systems within operational temperature ranges.