透平膨胀机及发展动态

比较了国内外常规透平膨胀机的主要技术参数 ;重点介绍了国外带液透平膨胀机、全液体透平膨胀机、能量回收用透平膨胀机和磁悬浮轴承透平膨胀机的发展动态     

低温氦气体轴承透平膨胀机实验系统设计

设计了一套氦透平膨胀机实验系统,该系统可以用来对工作在液氢—常温区范围内的不同规格的氦透平膨胀机进行性能测试,还可以用于开展以氦为工质的低温环境下透平膨胀机实验研究,以期掌握氦透平膨胀机的关键技术并进一步提高氦透平膨胀机的性能。     

160万m~3/d天然气透平膨胀机的研制

介绍了160万m3/d天然气透平膨胀机的设计参数和运行参数,重点分析了透平膨胀机设计中遇到的问题及解决措施,调整设计参数和运行参数后,透平膨胀机运行性能良好,最后总结了天然气透平膨胀机设计中的经验教训。     

增压透平膨胀机

介绍了增压透平膨胀机的应用概况和主要特点，分析了增压器给膨胀机前气体增压用的增压透平膨胀机的应用条件，提出了单级透平膨胀机的等熵比焓降最大允许值的问题。给出了增压透平膨胀机的主要参数关系式。     

低温氦气体轴承透平膨胀机的设计

针对我国氦透平膨胀机的研制任务，设计了一台氦气体轴承透平膨胀机。从机械性能方面就该氦透平膨胀机开展了理论与试验研究，以高稳定性为主要目标进行了氦透平膨胀机的结构设计，实现了绝热及密封、快速装拆等要求。氦透平常温、低温实验证明该机具有良好的热力性能及机械性能，本文侧重于对该氦透平膨胀机结构设计的探讨。     

大功率电涡流制动氦透平膨胀机在EAST氦制冷机中的控制与调试

为保障系统的制冷量与可靠性,EAST托卡马克装置2k W氦制冷机采用了动压气体轴承电涡流制动氦透平膨胀机替代原有的油气混合轴承氦透平膨胀机。新电涡流制动氦透平膨胀机配合转子冷却回路运行,制动功率最大可达10 k W。氦透平膨胀机采用全动压径向气体轴承,而下止推轴承则引入静压气体用于增加止推轴承的承载力。目前,大功率电涡流制动氦透平膨胀机已完成在EAST氦制冷机中的安装与调试运行。介绍了电涡流制动氦透平膨胀机的测量与控制设计,在调试运行的基础上总结了氦透平膨胀机的启动与停机控制流程,并对其低温调试进行了详细分析。调试结果表明,电涡流制动的应用简化了氦透平膨胀机的启动、停机与操作流程,有助于EAST氦制冷机全自动控制的实现。     

低温装置用高速透平膨胀机

介绍近年苏联在透平膨胀机方面发展的动向与水准。主要是高压透平膨胀机、低温氦装置的透平膨胀机、液-汽透平膨胀机的应用情况、结构与性能曲线。图6。     

透平膨胀机联锁报警改造

针对中控室内的操作员不易发现空分设备透平膨胀机联锁时的报警提示,设计了一套透平膨胀机联锁声光报警装置,从而使当班操作人员能及时发现透平膨胀机的联锁报警情况。     

采用不同损失模型的低温透平膨胀机性能分析

针对氦气低温透平膨胀机变工况热力性能预测,研究了透平膨胀机各通流部分损失机理,并根据一维无量纲流动控制方程,采用基于焓降的损失系数分析了各部件内流动损失,结合各部件流动特性,确定了适合各通流部件的损失系数计算关联式,进一步开展了氦低温透平膨胀机变膨胀比和变转速的热力性能模拟研究,绘制了透平性能曲线,获得了透平膨胀机变膨...     

氦制冷系统气体轴承透平膨胀机设计

描述了氦制冷系统的流程设计,根据流程确定系统关键部件透平膨胀机的参数,设计并研制了一台氦气透平膨胀机.为达到氦透平膨胀机高速稳定性及高绝热效率的要求,采用NREC对氦透平膨胀机优化通流部分,采用FLUENT分析气体轴承性能,优化气体轴承机构,采用ANSYS分析优化转子结构参数,提高转子临界转速.现场试验结果表明优化设计后的氦透平膨胀机,在转速12万转/分钟稳定运行,绝热效率达到72％以上,达到了系统设计要求.     

金属材料试样制备与力学性能试验结果的相关性第一讲试样的取样部位及机加工与力学性能试验结果的相关性

介绍了金属材料试样制备与力学性能试验结果的相关性。对国家标准中关于力学性能试验试样取样和机加工的要求、力学试验取样和制样过程中需要注意的问题、机加工质量的检验等问题进行了讨论。结果表明金属材料试验试样的制备与力学性能试验的结果有着非常密切的相关性,由于这个原因,力学试验试样的取样和机加工必须严格按照国家标准的要求进行,机加工后必须检验加工质量,以保证力学试验结果的正确性。     

Treasure of the Past IX: Exposure Standardization of Iodine-125 Seeds Used for Brachytherapy

A method for calibrating iodine-125 seeds in terms of exposure has been established. The standard free-air ionization chamber, used for measuring soft x rays, was chosen for the measurements. Arrays of four to six seeds were used to enhance the ionization-current-to-background-current ratio. Seeds from an array were measured individually in a re-entrant chamber. The quotient of the exposure rate for the array by the sum of the ionization currents in the re-entrant chamber is the calibration factor for the re-entrant chamber. Calibration factors were established for three types of iodine-125 seeds. The overall uncertainty for the seed exposure calibrations is less than 6%.     

Approximating the risk for time-to-failure models through using statistics of extremes

This paper studies the approximation of the partitioned multiobjective risk method's (PMRM) extreme event risk function for time-to-failure models. The analytic expression of the approximation for the extreme event risk function is derived through the use of the statistics of extremes for the case where the underlying distribution is of an extreme-value type III for minima. This analytic expression provides an effective theoretical tool for understanding the behavior of conditional expected values for time-to-failure models for a large class of distribution functions used in reliability. The results are confirmed for example problems of exponential and uniform distributions.     

Benchmark problems for wave propagation in elastic materials

The application of the new numerical approach for elastodynamics problems developed in our previous paper and based on the new solution strategy and the new time-integration methods is considered for 1D and 2D axisymmetric impact problems. It is not easy to solve these problems accurately because the exact solutions of the corresponding semi-discrete elastodynamics problems contain a large number of spurious high-frequency oscillations. We use the 1D impact problem for the calibration of a new analytical expression describing the minimum amount of numerical dissipation necessary for the new time-integration method used for filtering spurious oscillations. Then, we show that the new numerical approach for elastodynamics along with the new expression for numerical dissipation for the first time yield accurate and non-oscillatory solutions of the considered impact problems. The comparison of effectiveness of linear and quadratic elements as well as rectangular and triangular finite elements for elastodynamics problems is also considered.     

Flow fields in shell-and-tube condensers: comparison of a pure refrigerant and a binary mixture

Detailed 2D CFD calculations for vapour flow field and rate of condensation are carried out for a geometry similar to a real shell-and-tube condenser with 100 tubes, with condensation on the shell-side. The differences in vapour flow behaviour are investigated for pure R22 and for a binary mixture of R32 and R134a, which has a gliding temperature difference of 5.5 K. It is shown that, the flow field for a zeotropic mixture is significantly different from that for a pure fluid. The nature of the mixture flow causes the vapour and condensate to flow counter-currently in part of the condenser. Adjustments of the inlet design turn out to influence the rate of heat transfer by up to 24% for the conditions tested, with greater influence on heat transfer for lower driving forces.     

A Rational Fundamental Equation of State for Pentafluoroethane with Theoretical and Experimental Bases

A fundamental equation of state for pentafluoroethane was established on the basis of not only assessment of the experimental data but also by introducing parameters for virial coefficients having a theoretical background in statistical thermodynamics. The equation of state has a range of validity for temperatures from the triple point up to 500 K and pressures up to 70 MPa. The estimated uncertainties of the equation are 0.1% for the vapor pressure, 0.15% in density for the saturated-liquid phase, 0.5% in density for the saturated-vapor phase, 0.1% in density for the liquid phase, 0.1% in pressure for the gaseous phase, 0.5% in density for the supercritical region, 0.01% in speed of sound for the gaseous phase, 0.9% in speed of sound for the liquid phase, 0.5% in isobaric specific heat for the liquid phase, and 1.2% in isochoric specific heat for the liquid phase. The derived specific heats in the gaseous phase are close to the values from the virial equation of state with the second and third virial coefficients derived from intermolecular potential models and precise speed-of-sound measurements.     

Kriterien des Betriebsfestigkeitsnachweises für die Festlegung der Versuchslaufzeit bei der Substitution von Stahl- durch Aluminiumbauteile am Beispiel von Nutzfahrzeugrädern

The experimental structural durability proof bases on a damage equivalent shortening of the design spectrum into a test spectrum with reduced length taking statistics founded safety factors into account. Historically, test spectra were first derived for steel parts using Woehler-lines for steel; the damage equivalence was calculated by applying the Palmgren-Miner rule with the modification according to Haibach. When aluminium parts were introduced later, the question arose, whether test spectra developed for steel parts could be applied without modifications for their durability proof. Caused by different slopes of aluminium before and after the knee-point, the test spectra derived for steel wheels result for aluminium components a lower cumulated damage in comparison to the design spectra. This fact requires a longer test duration for aluminium components when test spectra or proving grounds developed for steel components are used. By the example of steel and aluminium wheels for commercial vehicles with comparable fatigue critical areas, the material dependent features regarding the required test life for the structural durability proof of aluminium parts are demonstrated.     

基于“互联网+”平台的老年人数字化产品服务设计

“5G”时代背景下,推动老年人数字化产品服务设计的创新发展已成为迫切的需要。研究论述了“互联网+”平台下老年人数字化产品服务设计遵循的原则与老年人数字化产品发展的趋势和前景。通过分析传统产品设计行业中关于老年人产品设计的设计原则和方向,总结了当今老年人数字化产品存在的缺乏针对性和创新服务设计的问题。并且在老年人感官感觉特征、生理行为特征和心理情感特征的基础上,研究了老年手机等案例,分析并论述了老年人数字化产品服务设计的原则。以老年人数字化产品服务设计为例,探讨了“互联网+”模式下,针对特定群体的数字化产品服务设计应遵循的简洁性、易用性、安全性和可靠性基本原则,综合“互联网+”平台、产品服务设计、数字信息技术等创新平台与技术,为促进老年人数字化产品的发展提供了设计策略和参考。     

A hybrid finite difference/helmholtz integral scheme for ultrasonic scattering

Two techniques for analyzing the scattering of elastic waves by flaws are combined in a hybrid model. One is a finite difference scheme for handling the details of the interaction with the flaw, the other is a Helmholtz integral scheme for extending the results into the far field. Results are given for the diffraction coefficients for a semi-infinite thin crack, and for a 270° corner.     

Coating material innovation in conjunction with optimized deposition technologies

Concentrating on physical vapour deposition methods several examples of recently developed coating materials for optical applications were studied for film deposition with optimized coating technologies: mixed evaporation materials for ion assisted deposition with modern plasma ion sources, planar metal and oxide sputter targets for Direct Current (DC) and Mid-Frequency (MF) pulsed sputter deposition and planar and rotatable sputter targets of transparent conductive oxides (TCO) for large-area sputter deposition.Films from specially designed titania based mixed evaporation materials deposited with new plasma ion sources and possible operation with pure oxygen showed extended ranges of the ratio between refractive index and structural film stress, hence there is an increased potential for the reduction of the total coating stress in High-Low alternating stacks and for coating plastics.DC and MF-pulsed sputtering of niobium metal and suboxide targets for optical coatings yielded essential benefits of the suboxide targets in a range of practical coating conditions (for absent in-situ post-oxidation ability): higher refractive index and deposition rate, better reproducibility and easier process control, and the potential for co-deposition of several targets.Technological progress in the manufacture of rotatable indium tin oxide (ITO) targets with regard to higher wall-thickness and density was shown to be reflected in higher material stock and coater up-time, economical deposition rates and stable process behaviour. Both for the rotatable ITO targets and higher-dense aluminum-doped zinc oxide (AZO) planar targets values of film transmittance and resistivity were in the range of the best values industrially achieved for films from the respective planar targets. The results for the rotatable ITO and planar AZO targets point to equally optimized process and film properties for the optimized rotatable AZO targets currently in testing.