间接蒸发冷却-喷射制冷一次回风空调系统分析

本文提出一种以干空气能与低品位能源联合驱动的间接蒸发冷却-喷射制冷一次回风空调系统,介绍系统工作原理及流程,建立系统数学模型,并分析一次回风空调系统(间接蒸发冷却—喷射制冷)主要性能随新风比从0.2到1的变化情况,当新风比逐渐减小时,蒸发器空气侧进口温度、工作流体、引射流体质量流量均逐渐减小,制冷剂的蒸发温度和引射流体与新风质量流量比均逐渐增大。在满足相同室内空调冷负荷需求时,一次回风空调系统(新风比0.2)跟直流式空调系统相比,总制冷量可减少59.3%,耗电量可节省52.7%,具有相当大的节能效益,值得进一步实验研究。     

转轮除湿复合式空调系统的探讨

转轮除湿复合式空调系统利用转轮除湿处理新风用于承担室内湿负荷,室内显热冷负荷和新风显热冷负荷由干冷设备承担,可有效地控制室内温度和湿度.复合式空调系统采用热回收装置可有效地节约新风冷负荷和提高除湿能力,当新风送风温度等于室内设计温度时,系统冷水采用高温冷水(18/21℃),可有效地提高制冷机组性能系数,节约制冷能耗42.83%.但转轮除湿再生能耗过高,复合式空调系统总能耗远大于传统空调系统,降低转轮除湿再生能耗是复合式空调系统应用的关键问题.     

蒸发器冷冻除湿特性模拟分析与优化研究

为了冷冻除湿系统更加高效运行,本文对冷冻除湿系统进行模拟计算,定量分析了除湿量与蒸发器进口风速、干球温度、相对湿度之间的关系。结果表明:在一定的进风温度和湿度情况下,随着风速的增大,除湿量先增大后减小;在进口空气的含湿量和风速一定时,随着进口空气干球温度的升高,系统的除湿量逐渐降低;进口空气干球温度在21～36℃,相对湿度在40%～85%之间变化时,进口空气湿球温度与最佳COP下对应的蒸发温度差值约为10℃;最佳制冷工况下的蒸发温度与最大除湿工况下的蒸发温度差值存在线性关系;模型值与实验值相比,误差在±10%以内。     

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。     

初探蒸发冷却—机械制冷复合空调系统

根据目前的研究状况,蒸发冷却制冷方式必须与机械制冷结合才能够在中等湿度地区和湿度地区达到要求的制冷温度.文章分析了半集中式蒸发冷却—机械制冷复合空调系统各部分的制冷原理,针对中等湿度地区分析各季节空气处理过程.同时,对干工况风机盘管的应用也做了分析.为蒸发冷却与机械制冷结合的空调机组在中等湿度地区的应用提供了理论参考.     

基于蒸发冷却与机械制冷相结合的毛细管辐射空调系统的设计计算

针对中等湿度和高湿度地区的气候特点,提出一种新型的节能环保型空调系统—基于蒸发冷却与机械制冷相结合的毛细管辐射空调系统。该系统中,蒸发冷却与风冷热泵组合式冷热水机组夏季制取高温冷水供给毛细管辐射末端,承担室内显热负荷,冬季制取热水;蒸发冷却新风机组制取新风送到室内,承担室内潜热负荷和部分显热负荷。文中以西安为例,分析了其节能性和舒适性特点,并结合具体例子对空气处理过程进行了分析计算。     

制冷机房冷却侧大温差节能特性分析

据统计,约40%的建筑能耗为空调系统能耗,空调系统能耗中大约有60%能耗来自制冷机房。由此可知,制冷机房节能是建筑节能的关键。目前,对制冷机房中冷冻侧大温差的节能技术有了大量的研究和实际应用。但是,对于冷却侧大温差的节能研究仍有待发展。目前设计师大多采用32/37℃的冷却水进出水温进行制冷系统的设计。为了给设计师提供冷却侧大温差的设计参考,通过能耗模拟软件对采用冷却侧大温差设计的制冷机房进行能耗预测,并根据模拟结果得到制冷机房最优的大温差设计方案。结果表明:当冷却侧温差由5℃增加至7℃时,冷却水进出水温为32/39℃的节能率(8%～9%)比31/38℃的节能率(约3%)更高。将制冷机房的冷却侧温差加大至8、9、10℃时,杭州、北京、广州均为8℃温差(冷却水进出水温为32/40℃)时最节能;而昆明则是10℃温差(冷却水进出水温为28/38℃)时最节能。     

模拟通信基站应用露点间接蒸发冷却空调技术的实验研究

为了进一步降低蒸发冷却空调技术应用于通信基站的送风温度,基于露点间接蒸发冷却空调技术,提出应用露点间接-直接蒸发冷却空调机组的直流式系统和应用露点间接-板式间接蒸发冷却空调机组的循环式系统。2011年8月1—10日,对福州地区应用这2种系统的一模拟通信基站进行测试,分析机组的降温效果、系统效率评价方法及基站内温湿度分布,并对直流式系统和循环式系统的特征进行比较。实验结果表明,2台机组的送风温度大约在室外空气湿球温度±1℃之间波动,送风的相对湿度在80%～95%之间,机组温降大约为室外空气干/湿球温度之差。     

新型流态冰蒸发制冷循环及制冰量性能分析

介绍了蒸发过冷水制冰原理及系统流程,分析了相应的蒸发制冷循环,对单位质量(1k)干空气制冰量性能及影响因素进行了研究并建立了相关数学模型,计算结果显示,水的初始温度越高单位质量干空气制冰量越低,而单位质量干空气制冰量相同时水温越高对应的蒸发水量则越大,同时随着空气出口相对湿度增大,单位质量干空气制冰量也随之增加.另外,...     

空调系统新风机组组合方式的研究

对目前我国存在的新风机组进行了大致分类,分别介绍了净化空调系统新风机组、半集中式空调系统新风机组和蒸发冷却与机械制冷相结合的新风机组,着重介绍了目前干燥地区半集中式空调系统中使用的蒸发冷却空调新风机组,最后针对蒸发冷却空调新风机组存在的不足提出了蒸发冷却与机械制冷相结合的三级复合式新风机组,从热湿交换角度和h-d图上对该机组的组合方式进行了分析,总结出了一种不仅能在干燥地区使用,同时能在中、高湿度地区使用的全年性蒸发冷却空调新风机组。     

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 ...