新型谐振管耦合型双效斯特林制冷机的数值模拟

结合经典双效斯特林制冷机结构与热声理论,提出一种谐振管耦合型双效斯特林制冷机,采用声学谐振管耦合斯特林发动机与斯特林制冷机,从而实现热驱动制冷,具有结构简单、潜在效率高、可靠性高、绿色环保的优点,在小型天然气液化、冷电联供以及空间探测领域有较大的应用潜力。针对实验室现有发动机和制冷机的参数,采用模拟软件Sage搭建了计算模型,计算验证了该结构的可行性。计算结果表明,在充气压力为3 MPa,工作频率为50 Hz,发动机压比为1.3条件下,该系统在80 K的制冷温度可获得210 W制冷量,整机效率为11.3%。同时进一步探究了系统内声场分布和主要部件损失,研究表明回热器内部声场偏离行波声场,谐振管中粘性损失较大和制冷机输入声功偏小是当前整机效率较低的主要原因。如果进行合理的优化设计,此类系统可以实现25%以上的整机效率。     

深冷文献消息(国内)

2007001 300Hz脉冲管制冷机特性研究；2007002　压比对回热器性能影响的理论分析；2007003　斯特林型脉冲管制冷机中压缩机与冷指耦合实验研究；2007004　液氮浴中不锈钢板动态冷却过程试验及模拟分析；2007005　EAST装置2kW／4．5K氦制冷机透平膨胀机的测试     

脉管型斯特林制冷机的实验研究

对脉管型斯特林制冷机用于普冷的可行性进行了分析研究。用实验的方法对脉管到斯特林制冷机和单纯的斯特林制冷机的性能进行了对比，得出了在２４５Ｋ以上温区脉管型斯特林制冷机的性能优于单纯的斯特林制冷机的重要结论．对小孔和脉管长度变化对脉管型斯特林制冷机性能的影响进行了讨论．     

分置式斯特林制冷机参数的优化

本文建立了分置式斯特林制冷机的优化设计模型，讨论了分置式制冷机的特点、优化设计及其数学模型中的特殊问题，考虑了制冷机中存在的主要冷量损失和直接功耗损失，选用了制冷机的12个主要结构和运行参数作为设计变量。实例计算中得到的优化结果与实验统计数据吻合较好。     

斯特林制冷机分层回热器优化设计与实验

为了提高斯特林制冷机在低温下的性能,把分层填充回热器结构应用于低温斯特林制冷机中。利用REGEN3.3对自行研制的斯特林制冷机用分层回热器进行了优化设计,并对此进行了实验研究。研究结果表明,回热器采用恰当的分层方式能大幅度提高制冷机的性能。该斯特林制冷机与优化前相比,其膨胀机效率提高了52.8%,整机效率提高了79.8%。     

斯特林制冷机回热器热损研究

讨论了回热器的各种损失对斯特林制冷机的影响,对斯特林制冷机回热器的结构和丝网填料进行了分析,并模拟分析各种损失的影响.研究表明,回热器的结构、丝网填料对制冷机的性能有重大影响.     

斯特林制冷机的计算机辅助调机

通过对双自由度斯特林制冷机振动系统模型的分析 ,建立了计算机仿真调相角模型。在模型求解过程中 ,通过改变弹簧参数来优化斯特林制冷机的压力波和制冷机回热器位移之间的相位差 ,使其接近最优相角要求 ,来辅助调节系统的工作参数。模型模拟的结果与实验结果能较好的吻合     

可逆脉管制冷循环与斯特林制冷循环的比较

建立了可逆脉管制冷机的等温－绝热模型，着重考虑脉管中过程对制冷机性能的影响，并与斯特林制冷机等温模型的计算机结果进行比较。结果表明，在理想工况下，可逆脉管制冷机的效率约为斯特林制冷机的８５％，制冷量约为７２％。可逆脉管制冷机配气活塞的最佳运动相位与斯特林制冷机基本相同。     

斯特林制冷机的最佳火用输出率

研究导热和回热损失对斯特林制冷机火用优化性能的影响，导出制冷机的最佳火用输出率与制冷系数以及与制冷率间的关系。由此揭示了斯特林制冷机火用优化性能的主要特征，并与制冷率优化性能作了比较，获得一些对实际制冷机有指导意义的新结论。     

平行轴布置的斯特林制冷机设计原理与应用分析

稳定平台光电系统设计常用线性斯特林制冷机以达到振动小的要求,但以牺牲重量、尺寸、功耗为代价。旋转式制冷机功耗低、尺寸小却振动大;设计平行轴布置斯特林制冷机以减小旋转制冷机对稳定平台的振动影响。分析了旋转制冷机振动源与稳定平台框架的系统刚性特点;从系统耦合的角度,通过力学模型分析平行轴布置斯特林制冷机振动源叠加的情况,根据分析结果提出利用稳定平台刚度高的方向吸收制冷机翻倒力矩的激励,降低平台的抖动程度。最后指出平行轴布置斯特林制冷机与框架结合应用的合理性与可行性。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.