铁路客车空调负荷研究

采用非稳定传热计算法分别计算了南北向和东西向,以及夕发朝至运行时硬座空调客车的动态负荷。计算结果表明,受外界环境的影响,铁路空调客车在运行时空调负荷变化较大,在不同区间运行的铁路客车,其空调动态负荷的最大值不尽相同。因此认为,不能仅依据TB1951—87《客车空调设计参数》来确定空调机组制冷量,而应根据客车运行区间的最大动态负荷设计空调机组；若能根据客车动态负荷变化趋势,实现客车空调机组的变频调节和自动控制,可达到提高客车舒适度和节能的目的。     

空调客车车内计算参数的优化与节能

本文根据PMV—PPD指标，分析了K25型软卧客车的车内空调计算参数——空气温度和湿度对热舒适性的影响，并通过计算软卧客车的负荷和制冷量分析了温、湿度对空调能耗的影响。最后指出：优化车厢内空调计算参数，对铁路客车空调的节能有重要的意义。     

铁路客车空调机组的振动性能试验研究

本文针对铁路客车空调机组的振动性能进行了研究,通过试验确定了其在各方向上的固有振动频率,并首次结合铁路客车的振动试验结果,对客车运行条件下车体振动可能对空调机组产生的影响进行了分析。认为应改善空调机组的垂向振动特性,避免产生共振。     

外界环境温度对旅客列车的影响

综合考虑了列车运行时外界环境温度的变化,以1527次和1528次空调列车为例,计算得到列车运行时沿途的空气温度、综合温度及车厢壁面温度的波动规律,反映了外界环境温度对旅客列车的影响,为今后列车空调动态负荷计算及列车空调机组实时运行调节提供了理论依据。     

不同气候区地铁列车空调全年动态负荷特性

车厢内空调负荷决定了列车空调机组的设计容量，目前车厢负荷通常按照国家标准规定的稳定负荷进行计算，实际上车外环境气象参数和车内载客量是实时变化的。因此，选取多个城市作为各气候区的典型城市，基于地铁列车空调负荷计算方法，对不同气候区典型城市地铁列车单节车厢内空调全年动态负荷进行计算，以探索不同气候区的地铁列车单节车厢空调的负荷特性和适合相应气候区的单台热泵空调机组设计容量。     

地铁车站设备区空调负荷动态特性分析及系统优化

通过对广州地铁某车站设备区的研究,分析全年逐时空调负荷计算和空调机组运行负荷的动态变化状况,得出地铁车站设备区空调实际负荷特性及机组冷冻水进、出水温差、设备区室内温度、室内焓值等各项性能参数的变化规律,并以此对地铁车站设备区通风空调负荷的常用工程设计及运行模式进行评估,对地铁设备区通风空调系统提出优化建议、改进措施以及可行和节能的系统运行方案。     

列车空调机组运行性能研究

建立了铁路空调列车车项单元式空调机组中冷凝器、蒸发器、毛细管、压缩机四大部件模型和系统仿真模型，对空调机组进行系统仿真计算。并分析了车外和车内空气温度变化对空调机组运行性能的影响．     

广州电信大厦中央空调系统冷水机组运行负荷率分析

本文根据广州电信大厦中央空调系统2007年全年的运行数据,并结合办公楼空调使用的特点,分析计算了该系统的全年逐时负荷的分布情况,机组负荷率的变化规律及配置运行情况。得出了4台机组的负荷率绝大部分都集中在60%～90%之间,冷水机组的启停及运行模式基本符合大厦全年负荷的时间分布及其性能指标,说明运行调节较合理。     

广州电信大厦中央空调系统冷水机组运行负荷率分析

本文根据广州电信大厦中央空调系统2007年全年的运行数据,并结合办公楼空调使用的特点,分析计算了该系统的全年逐时负荷的分布情况,机组负荷率的变化规律及配置运行情况。得出了4台机组的负荷率绝大部分都集中在60%~90%之间,冷水机组的启停及运行模式基本符合大厦全年负荷的时间分布及其性能指标,说明运行调节较合理。     

单元式空调机组制冷量不足的原因分析与解决方案

一、空调机组结构简介铁路客车空调机组的结构形式是集中单元式,单元式空调机组(简称空调机组)是将压缩机、冷凝器、冷凝风机、气液分离器、干燥过滤器、通风机、蒸发器和空气预热器等集中在一个箱体内组成完整的单元,具有体积小、结构紧凑、互换性好和检修方便等特点。单元式空调机组整体结构如图1所示。空调机组安装在车顶端部,空调控制柜安装在车内配电     

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.……     

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.     

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.     

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 ...