逆流式露点间接蒸发冷却器性能实验研究

本文研发了一种新型逆流式露点间接蒸发冷却器,并对其冷却性能进行实验研究。在焓差实验室内模拟干燥地区、中等湿度地区、高湿地区等多种工况条件,对该冷却器的湿球效率、露点效率、制冷量等进行测试分析。结果表明:在标准干燥工况(干球温度38℃,湿球温度23℃),二次空气/一次空气风量比=1.1条件下,该冷却器湿球效率可达105.6%,露点效率可达76%,制冷量为2.83 kW,干球温度温降可达15.2℃。模拟乌鲁木齐工况与标准干燥环境工况的实验结果表明,露点间接蒸发冷却技术在我国西北炎热干燥地区具有极大的优越性和广阔的应用前景。     

数据中心用露点间接蒸发冷却与机械制冷复合空调的实验研究

为了降低数据中心空调能耗并提高换热效率,本文提出一种应用于数据中心的流道结构为逆流和叉流结合的露点间接蒸发冷却与机械制冷复合空调,并搭建了实验台分别对干燥工况和高湿工况下回风温度为26℃和35℃的不同运行模式进行实验测试。实验结果表明:运行湿模式,当数据中心回风温度较低为26℃时,干燥工况下机组的湿球效率最高为97%;当数据中心回风温度较高为35℃时,干燥工况下机组的湿球效率约为110%,高湿工况下机组湿球效率为99%;运行混合模式,干燥工况下露点间接蒸发冷却器的湿球效率约为120%,高湿工况下露点间接蒸发冷却器的湿球效率约为110%。由测试结果可知,露点间接蒸发冷却技术在干燥地区更加适用,中等湿度和高湿地区需辅助机械制冷,尤其当回风温度较低时,高湿工况蒸发冷却应用受限,必须辅助机械制冷达到送风要求,回风温度较高时,蒸发冷却可以减少机械制冷的使用时间。     

露点蒸发冷却装置性能评价指标的研究

本文通过搭建逆流式露点蒸发冷却装置,实验研究了空气入口温度、湿度和风速对露点效率、湿球效率、?效比等各性能评价指标的影响,提出了能够反映湿通道潜热交换的强弱和装置性能的适用于露点蒸发冷却的评价指标——换热放大系数.研究结果表明:进口温度为33、相对湿度为22％时,当风速从1 m/s增至3 m/s,制冷量从29.5 kW...     

数据中心空气侧蒸发冷却技术性能及适用性分析

总结了空气侧蒸发冷却技术在数据中心的研究现状,对直接、间接及露点间接蒸发冷却技术的工作原理进行理论分析并对三者在高湿工况下的性能进行测试,结果表明,所测蒸发式冷气机最佳风速在1.8m/s;间接蒸发冷却空调机组最佳二/一次风量比为1.5;露点间接蒸发冷却空调机组最佳二/一次风量比为1.7,并且此时效率可达到96.5％,有...     

有冷凝和没有冷凝的板式间接蒸发冷却器性能分析比较

在不同的参数条件下，对一次空气通道有冷凝和没有冷凝的板式间接蒸发冷却过程进行了三维数值模拟。根据间接蒸发冷却过程的热力学特性，定义了间接蒸发冷却器的[火用]效率计算公式。通过对不同的入口速度、浓度以及通道宽度条件下的模拟和计算结果进行分析比较，得到了影响换热效率的因素，并从热力学第二定律的角度对换热器进行了[火用]分析。     

交叉式露点间接蒸发冷却空调机组性能测试研究

为了研究高湿度地区夏季交叉式露点间接蒸发冷却空调机组的性能,2013年7月1-12日在福建省福州市某公司对该空调机组进行了研究,通过测试和计算分析的得出：二一次最佳风量比为1.08,对应湿球效率为91％;最佳风量比下最佳淋水密度625kg/（m·h）;间歇供水时间是制冷15s、通风约为5～6min;最佳风量比和最佳淋水密度下的耗水指标为10.8L/h;制冷量为7.6kW、能效比为15.3.结果表明：交叉式露点间接蒸发冷却空调机组湿球效率接近100％,达到单独使用直接蒸发冷却的效果,而且还不增加空气的合湿量,同时,该机组不仅适合在高湿度地区,在中等湿度地区和干燥地区应用其制冷效果将会更好.     

基于露点板式间接蒸发冷却器空调机组特性的探讨

通过对目前国内外露点间接蒸发冷却技术的发展进行介绍,提出一种基于露点板式间接蒸发冷却器的空调机组—露点间接—直接蒸发冷却空调机组。并对此空调机组的原理和特性进行了分析,结果表明这种空调机组与传统露点间接蒸发冷却器相比,温降幅度大,可以进一步逼近室外空气的露点温度,是露点间接蒸发冷却技术的一个新发展。同时还对这一机组的性能测试提出了一些研究方法。     

间接蒸发冷却板式换热器换热性能的数值模拟

应用计算流体力学(CFD)方法建立了间接蒸发冷却板型换热器内三维层流流动与传热的数学物理模型;对影响蒸发冷却换热器换热性能的主要因素进行了数值计算和预测;通过计算表明,换热器通道间距、空气的迎面风速,以及一次风的干球温度的变化对换热器效率有很大的影响;分析了不同参数时通道内流场、能量场以及换热器效率的变化.     

循环水冷却用蒸发冷却冷水机组性能测试

针对目前工业领域存在的循环水冷却问题,设计采用蒸发冷却冷水机组实现循环水的冷却。该机组由立管间接蒸发冷却器、直接蒸发冷却填料、闭式换热盘管组成。对机组进行风量测试及热水试验,结果表明:机组在高湿度地区运行时,立管间接蒸发冷却器的最佳风量比(二次/一次)为0.79,机组的冷却效率高达65.2%;机组对50℃左右的循环水进行冷却,温降幅度为20℃,降温效果较好。最后针对测试中存在的主要问题提出改进措施。     

露点间接+直接蒸发冷却空调机组节能性分析

介绍露点间接+直接蒸发冷却空调机组节能工况点和一二次风量比以及效率的选择确定,计算机组在不同气候地区能耗和制冷量以及能效比,分析机组的节能性,指出合理的风机风量和风压、水泵流量和扬程以及淋水密度是露点间接+直接蒸发冷却空调机组节能设计的关键环节。为露点间接+直接蒸发冷却空调机组的设计和推广应用提供参考。     

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.     

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...     

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 ...