法国泰康商用风冷冷凝机组用R404A替代R502的应用研究

Ｒ５０２曾广泛使用于商用低温制冷系统中,但因其中含有ＣＦＣ成分,它的使用受到限制。Ｒ４０４Ａ（由ＨＦＣ１２／ＨＦＣ１４３ａ／ＨＦＣ１３４ａ组成）是一种对大气臭氧层无破坏的,可长期替代Ｒ５０２的混合制冷剂。作者首先用ＣＳＤ状态方程对这两种工质的热力学与制冷循环特性进行了理论上的计算,然后,在一台可使用Ｒ４０４Ａ的风冷压缩冷凝机组上进行了一系列的试验。采用第二制冷剂量热器法来测量机组的制冷量。系统中加装了一个水过冷器来控制节流前液体温度。试验中,控制蒸发温度在－４０～－１０℃之间变化,环境温度为３２℃和４０℃。为了测定过冷的影响,在一定的环境温度和蒸发温度下进行了各种过冷温度的试验。在同一台机组上,相同工况下进行了Ｒ４０４Ａ和Ｒ５０２的对比试验。计算和试验结果表明,Ｒ４０４Ａ具有与Ｒ５０２相近的制冷性能,特别是在蒸发温度高和冷凝温度低的情况下。在低温范围,Ｒ４０４Ａ的性能比Ｒ５０２略有下降。在所测的温度范围内,Ｒ４０４Ａ的排气温度都比Ｒ５０２低,这有利于压缩机工作的可靠性。     

HFC—134a／油的材料相容性研究

本文综合运用目前国际上的制冷剂材料相容性研究方法,试验研究了国产ＨＦＣ１３４ａ及润滑油与ＨＦＣ１３４ａ汽车空调材料的相容性,同时还研究了国产ＨＦＣ１３４ａ及进口润滑油与ＨＦＣ１３４ａ冰箱材料的相容性。结果表明,国产ＨＦＣ１３４ａ／油与目前ＨＦＣ１３４ａ汽车空调材料是相容的,国产ＨＦＣ１３４ａ与现有ＨＦＣ１３４ａ冰箱材料也是相容的。     

赝二元系LiF-CaAlF5相图

本文通过差热分析（ＤＴＡ）和Ｘ射线粉末衍射（ＸＲＤ）方法研究了赝二元系ＬｉＦＣａＡｌＦ５的相平衡关系,该赝二元系在ＬｉＦ：ＣａＡｌＦ５＝１：１处形成一致融熔化合物ＬｉＣａＡｌＦ６,其熔点为８１４℃,并分别在ＬｉＦ￣ＬｉＣａＡｌＦ６和ＬｉＣａＡｌＦ６￣ＣａＡｌＦ５区域形成两个共晶体系,采用坩埚下降法生长出氟化物激光晶体Ｃｒ＾３＋：ＬｉＣａＡｌＦ６。     

CFC问题及2000年制冷剂展望

阐述了ＣＦＣ问题的由来及所面临的课题，介绍了替代制冷剂ＨＣＦ２２、ＨＣＦＣ１２３、ＨＣＦＣ１４１ｂ、ＨＣＦＣ１４２ｂ、ＨＦＣ１３４ａ、Ｒ７１７（ＮＨ３）、ＨＦＣ２４５ｃａ、Ｒ７４４（ＣＯ２）、Ｒ７２９（空气）等各自的优缺点。     

环保节能型空调器

本文系统回顾了以ＨＦＣ－３２／ＨＦＣ－１３４ａ替代ＨＣＦＣ－２２在家用空调器中应用的理论分析和实验研究概况。内容涉及工质的筛选与热力学性质的测算,混合工质与润滑油互溶性实验,绕组耐Ｒ３２／Ｒ１３４ａ实验。制冷剂可燃性实验,压缩机性能对比实验,空调器整机性能对比实验。理论与实验均证实符合国际环保要求的混合工质不但可以替代ＨＣＦＣ－２２而且节能。     

二元混合工质灌注式替代的冰箱性能实验研究

本文从理论制冷循环上计算分析得出了几种全ＨＦＣ混合替代物ＨＦＣ３２／ＨＦＣ１３４ａ,ＨＦＣ３２／ＨＦＣ１５２ａ,ＨＦＣ１２５／ＨＦＣ１３４ａ和ＨＦＣ１２５／ＨＦＣ１５２ａ,并对这进行了冰箱实验研究。     

R152a／R134a的汽液相平衡分析

本文用ＭＨ８１方程计算了Ｒ１５２ａ／Ｒ１３４ａ在２４３．１５Ｋ￣３１３．１５Ｋ范围内的等温汽液相平衡。计算表明：Ｒ１５２ａ／Ｒ１３４ａ是共沸混合物，有一最低共沸点。     

混合工质R32／R134a的压缩机性能试验

本文介绍了用同一台压缩机， 充灌四种不同比例的Ｒ３２／Ｒ１３４ａ 混合工质与Ｒ２２及Ｒ１３４ａ 的对比试验。通过测量制冷量、输入功率、能效比以及壳体温度等主要性能， 从理论上定性和定量地阐明了Ｒ３２／Ｒ１３４ａ在空调器中替代Ｒ２２ 的可行性和优越性。     

使用HFC134a的冰箱用旋转式压缩机性能优化的途径

冰箱用旋转式压缩机中用ＨＦＣ１３４ａ替代ＣＦＣ１２后，由于ＨＦＣ１３４ａ的热力学与传输特性不同于ＣＦＣ１２，使压缩机的性能下降。本文从旋转式压缩机的电机效率、隙容积、传热损失及润滑油粘性等途径来探讨改进ＨＦＣ１３４ａ旋转式压缩机的途径。     

我国已能工业化生产HFC－134a

我国已能工业化生产ＨＦＣ－１３４ａ中科院上海有机化学研究所采用我国发明的催化新技术，使反应温度和压力大大降低，从而解决了国外一直未能解决的液相法工业生产ＨＦＣ－１３４ａ的难题。上海有机化学研究所由液相法生产ＨＦＣ－１３４ａ，具有产品质量好、纯度高、产...     

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.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

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.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

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 ...