双制冷温度双工质吸收制冷系统Ⅱ的模拟

为克服在较高温度的热源下只用氨作为制冷剂时采用二级再生流程系统操作压力高的弊病,提出了一种新的吸收制冷系统.将水-溴化锂和氨-硝酸锂二系统耦合,在后者所组成的系统2中设置二个不同蒸发温度的蒸发器.对该系统的操作性能进行了热力学模拟,分析讨论了热源温度、冷却水温度和低温蒸发温度的影响及系统适宜的操作条件.在较高的热源温度和较宽的操作条件下,系统操作性能稳定,其制冷性能系数COP可以稳定在0.95以上,稍低于类似条件下只用水-溴化锂作为工质的二级再生系统,但相应的制冷温度分别为1℃和-5℃,是一种很有实用价值的吸收制冷系统.     

Water-lithium bromide-lithium nitrate三元工质双效吸收式制冷循环的研究

比较了水-溴化锂-硝酸锂三元工质与传统的水-溴化锂工质的双效吸收式制冷循环,分析了直燃型双效制冷系统.结果表明:采用新工质后,系统的热力系数COP有了明显的提高,其它表征系统热力性能的经济指标也均有不同程度的改善,尤其在商燃型双效冷热水机组中有明显的优势,热力系数COP提高约30%,溶液循环倍率降低12%.因此,该新工质与传统的水-溴化锂工质相比,具有较好的热力性能.     

以[mmim]DMP-甲醇为工质对的吸收式制冷循环研究

采用离子液体[mmim]DMP-甲醇作为吸收式制冷系统工质对,运用文献提出的[mmim]DMP-甲醇二元溶液经验方程进行制冷循环计算研究,并将此系统的工作压力、COP等与相同工况下的溴化锂-水、氨-水制冷循环进行比较。研究结果表明：[mmim]DMP-甲醇工质对制冷系统工作压力要求适中,COP稍高于NH3／H2O系统,低于H2O／LiBr系统;[mmim]DMP-甲醇溶液对金属无腐蚀,其适用范围要大于H2O／LiBr系统,具有一定的应用价值。     

Water—lithium bromide—lithium nitrate三元工双效吸收式制冷循环的研究质

比较了水-溴化锂-硝酸锂三元工质与传统的水一溴化锂工质的双效吸收式制冷循环,分析了直燃型双效制冷系统。结果表明：采用新工质后,系统的热力系数COP有了明显的提高,其它表征系统热力性能的经济指标也均有不同程度的改善,尤其在直燃型双效冷热水机组中有明显的优势,热力系数COP提高约30％,溶液循环倍率降低12％。因此,该新工质与传统的水-溴化锂工质相比,具有较好的热力性能。     

氯化钙-氨吸附式制冷的实验研究

在以氯化钙-氨为工质对的两床吸附式制冷系统上进行了实验研究,得出了不同热源温度下,以氯化钙-氨为工质对的连续循环制冷系统的制冷量、性能参数COP随时间的变化关系。所得结果可为进一步的实验研究和工程设计提供指导。     

低温热源驱动的二级吸附冷冻循环实验研究与性能分析

在冷冻应用方面,传统的吸附式制冷工质对在热源温度低于90℃、冷凝温度高于25℃的条件下,很难实现-10℃以下的冷冻。为了实现100℃以下的太阳能或废热利用,这里提出了二级吸附式制冷循环,建立了性能测试实验台。采用CaCl2-BaCl2-NH3作为工质对,利用85℃热源驱动,测试不同蒸发温度与冷凝温度下吸附剂的吸附与解吸性能。结果表明,二级吸附式制冷能够实现-20℃下的冷量输出,同时,冷却水温度为25℃时,氯化钙的循环吸附量、二级吸附式制冷COP与SCP分别为0.598kg/kg,0.24,106.6W/kg。     

采用离子液体-水工质对的GAX吸收式制冷循环性能研究

热驱动的吸收式制冷技术是太阳能利用和工业余热回收的重要途径,其中GAX(吸收发生换热)吸收式循环具有高效、效率可随热源温度变化的特点。本文提出采用无结晶风险的离子液体工质对,并使用NRTL模型对离子液体工质对性质进行计算,并对GAX吸收式制冷循环进行性能计算。结果表明:采用1,3-二甲基咪唑磷酸二甲酯盐([DMIM][DMP]/水工质对可以使用GAX吸收式循环,且在发生温度较高的情况下COP能够达到约1.02,比相同特定工况下的单效循环COP提升27.5%,比采用溴化锂/水工质对的吸收式循环具有更加优异的性能。     

太阳能吸收式串联流程制冷系统与性能分析

本文提出了一种串联流程的以太阳能与燃气双热源供热的溴化锂吸收式制冷系统。介绍了当前太阳能吸收式制冷的发展概况。对双热源制冷系统原理进行介绍,简述了制冷机内工质循环流程,并模拟分析了系统的热力性能,得到高压发生器与低压发生器在不同放气范围时系统制冷系数与双热源的供热分配情况。分析了一天内不同时段制冷系统运行特性在不同太阳辐照度下的变化特点。结果证明太阳能与燃气双热源串联流程溴化锂吸收式制冷方案具有节能高效的优势。     

以TFE—TEGDME为工质的制冷循环分析

为初步了解新型工质TFE-TEGDME用于吸收式制冷中的可行性,在同样的设计条件下,对采用该工质的制冷系统进行中压双效复叠循环与基本GAX循环分析,计算得到基本GAX循环有较高的COP值.但在温度较高(140℃)时,较小的放气范围导致基本GAX循环COP值较低,运行性能较差.     

两级复合吸收式制冷循环研究

对以氨/水及水/溴化锂为工质的两级复合吸收式制冷循环进行计算分析后发现,该循环不仅提高了循环的COP值,而且也增大了制冷温度范围。但是只有在冷却水入口温度较低的情况下,循环才能获得较大的制冷温度范围。同时,循环随着冷却水入口温度的提高,最低制冷温度也随之上升,由于受到溴化锂溶液结晶和腐蚀问题的限制,Ⅱ级发生温度不能过高,放气范围不能过兢兢业业,否则会影响该循环的实际应用。     

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.