数据中心自然冷却技术研究进展

数据中心的能耗增长日益受到关注,其能耗的很大部分是用于机房冷却。采用节能冷却方法是节能减排的迫切要求,自然冷却技术是其中的有效方法之一。自然冷却技术的实施有三种主要方式:空气侧自然冷却、水侧自然冷却和热管自然冷却。空气侧自然冷却简便易行且节能效果好,但会影响室内空气质量和湿度。水侧自然冷却可以在原有的空调机组上改造实现,但由于增加了中间传热过程其节能效果有限。热管自然冷却避免了对室内环境的影响,且同时利用相变传热节能效果较好。本文总结了近年来这三种自然冷却技术的最新进展,为这一领域的研究提供参考。     

Extension of the vase life of cut daffodil flowers by rapid vacuum coolingProlongation de la durée de conservation en vase de jonquilles coupées par refroidissement rapide sous vide

Vacuum cooling has been widely used as a rapid cooling method for vegetables to enhance their quality and shelf life. The extension of vacuum cooling to the floricultural industry has great potential economic advantages. In the current study, vacuum cooling of freshly cut daffodils was carried out and their cooling processes were investigated. The vase life of vacuum cooled flowers with and without cold storage was studied. The results show that vacuum cooling can significantly extend the vase life of the flowers with and without cold storage and it is a very effective pre-cooling technique for cut flowers. Spraying water prior to vacuum cooling cannot only reduce the cooling time without any negative effects on vase life, but also weight loss. The reduction of weight loss is especially beneficial to vacuum cooling of vegetables.     

逆升压电子设备冷却系统控制方案的研究

分析了目前国内一些飞机基于三点温度控制方案的逆升压电子设备冷却系统的缺陷 ,提出了一种新的系统控制方案 ,即基于飞行速度和高度的逆升压电子设备冷却系统的控制方案。这一方案不需要人工干预 ,可实现全自动化。     

冷阱温度对蒸煮肉制品真空冷却效果的影响

真空冷却技术具有降温速度快、运行能耗低等优点,在食品冷链中得到了应用并迅速发展。本文以蒸煮肉制品为研究对象,开展蒸煮肉制品真空冷却效果实验,分析不同冷阱温度对冷却速率、质量变化和真空室内压力对冷却效果的影响。结果表明:不同的冷阱温度对蒸煮肉制品冷却速率、冷却前后的质量变化,以及对冷却过程中真空室内的压力产生不同的影响。另外,并非冷阱温度越低冷却效果越好,实验对比了冷阱温度为-15℃、-25℃和-35℃下的真空冷却过程,冷阱温度的最佳值为-25℃,冷却时间最少为320s。     

两级蒸发冷却空调运行优化实例分析

两级蒸发冷却技术因具有节能、环保以及改善室内空气品质等优点,在工程中得到了越来越广泛的应用,特别是因其投资少、运行节能且不存在直接蒸发冷却空调的室内相对湿度大、室内潮湿难忍等缺点,在国外得到了推广和实际应用。在两级蒸发冷却空调中,间接和直接蒸发冷却设备的冷却效率越高,则可得到的送风温度越低。本文针对兰州某网吧的两级蒸发冷却空调实际案例进行了细致的测试分析,并对存在的问题进行改进和优化,供有关设计、施工及管理人员参考。     

开式水蒸发空调系统的研究与应用

针对开式水蒸发冷却空调系统的相关研究以及应用测试情况,对几种分别由直接蒸发冷却、间接蒸发冷却以及两级蒸发冷却组成的开式空调系统的组成原理以及运行方式进行较为详细的阐述。测试结果及相关分析显示：各系统都具有较好的空气调节能力,能够满足区域性供冷要求;开式水蒸发空调系统结构简单、制冷效果良好,节能环保,具有优良的推广应用价值。     

On the Method of Air Jet Cooling in Green Manufacturing

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Thermal calculation of the ejection cooling tower and method of improving its efficiency

A mathematical model for thermal calculation of the ejection cooling tower has been proposed. New data on the effect of the air flow rate, meteorological conditions, heat load, and water pressure in the water distribution system of the cooling tower on the spray characteristics and water cooling have been obtained. A novel method of improving the efficiency of the ejection cooling tower has been developed.     

Effect of pressure on the vacuum cooling of iceberg lettuce

Vacuum cooling is known as a rapid evaporative cooling technique for any porous product which has free water. The aim of this paper is to apply vacuum cooling technique to the cooling of the iceberg lettuce and show the pressure effect on the cooling time and temperature decrease. The results of vacuum cooling are also compared with conventional cooling (cooling in refrigerator) for different temperatures. Vacuum cooling of iceberg lettuce at 0.7 kPa is about 13 times faster than conventional cooling of iceberg lettuce at 6 °C. It has been also found that it is not possible to decrease the iceberg lettuce temperature below 10 °C if vacuum cooling method is used and vacuum pressure is set to 1.5 kPa.     

Parametric study for the cooling of high temperature superconductor (HTS) current leads

The analysis of cooling of a binary HTS 20 kA current lead (CL) operating between 4.5 and 300 K has been carried out. Assuming that the HTS module is conduction-cooled, two cooling options for the copper heat exchanger (HEX) part of the CL have been considered, i.e. (1) cooling with a single flow of gaseous helium and (2) cooling with two flows of gaseous helium. The ideal refrigerator power required to cool the whole HTS CL has been calculated for both cooling scenarios and different values of input parameters and the thermodynamic optimization has been performed for both cooling options. The obtained results indicate that the cooling Option 2 cannot provide significant savings of the refrigerator power, as compared to the Option 1. However, it has been observed that at the same helium inlet temperature the temperature at the warm end of the HTS part, and the resulting number of HTS tapes, can be reduced in the Option 2 with respect to the Option 1.     

钼产品的中频炉快冷技术

阐述了中频炉快冷技术的原理及冷却效果。根据冷却原理对中频炉进行了改造,在保留内循环纯水冷却系统的基础上,增加了一套氢气循环快速风冷等统使之能够实现快速冷却。分析对比了自然冷却和快速冷却的时间及效率。检测了采用快冷技术后钼产品的性能,结果表明,快速冷却技术生产的产品性能均能达到金钼股份公司Q/JDC 016-2008企标要求,该技术可大大提高中频炉的生产效率。现该技术已经成功地在生产中实际应用,取得了很好的经济效益和社会效益。     

辐射供冷方式室内舒适性数值模拟

辐射供冷系统中辐射板的布置位置对人体舒适性有较大影响。本文采用Fluent软件对该系统进行数值模拟,比较7种组合方式下的室内热湿环境。研究结果表明,辐射板布置在墙面或者顶板与风机盘管组合的供冷方式均能够基本满足人体舒适性要求,地板辐射供冷与风机盘管复合供冷方式舒适性最差,顶面＋墙面＋风机盘管这一组合方式兼具顶板式和墙面式的特点,是7种组合方式中最舒适的方式。     

基于MRF模型的冷却辊冷却性能的CFD分析

目的在自行改进的FR300ELS型机组式凹版印刷机的冷却辊(喷淋式冷却辊)装置基础上,分别对传统式和喷淋式2种冷却辊的冷却性能进行温度分布的对比分析,研究喷淋式冷却辊的结构和性能优势。方法建立新旧2种冷却辊的MRF模型,利用CFD对冷却辊表面、轴向、周向的温度场分布进行仿真分析。结果得到了新旧2种冷却辊在印刷机稳定工作状态下的温度分布散点图及云图。结论喷淋式冷却辊与传统式冷却辊相比,它的温度分布更均匀、冷却效果更好、冷却效率更高。     

基于多维度物理参数影响的超高强钢热成形冷却流场仿真分析

目的 研究关键参数对超高强钢热成形模内淬火效果的影响规律,合理选择模具材料和冷却流场空间结构,达到冷却淬火后材料中条状马氏体含量最大的目的.方法 利用流体仿真软件Star–ccm+对超高强钢热成形模具冷却流场进行有限元模拟分析,采用7种不同热导率的热成形模具材料和直径为15、20、25、30、35 mm的冷却管道管径,...     

CONTINUOUS COOLING OF WET FOUNDRY SAND USING A FLUIDIZED BED

In order to establish the optimum cooling system for hot returned sand in metal casting processes, a mathematical model including simultaneous heat and mass transfer has been constructed. The present study is especially directed towards clarifying the dynamical behavior of sand cooling in a one-pass fluidized bed. A series of continuous cooling experiments has been made for various conditions. Characteristics of both transient and steady-state bed temperature are explained reasonably by the present model. Furthermore, a possible proposal has been given on the optimal operation, which raises heat exchange efficiency in fluidization cooling of hot molding sand.     

冷却速度对T91相变速度和产物的影响

本文研究了T91钢冷却过程中,不同冷却速度（10k/min（200k/min）对相变速度和产物的影响。研究表明不同的冷却速度生成的组织差别较大,在较低速冷却下（10k/min和30k/min）的组织为较多的先共析铁素体和板条马氏体,中速冷却（30k/min和50k/min）基本都为板条马氏体,在较高速冷却过程中（100k/min和200k/min）组织中除了板条马氏体还出现了片状马氏体,另外冷却速度还影响了相变开始点和相变速度。     

随焊激冷防止高强铝合金焊接热裂纹的数值模拟

采用热弹塑性有限元方法对随焊激冷防止焊接热裂纹的工艺过程进行了数值模拟 ,动态定量地描述了温度场、位移场和应变场的演变过程 ,清晰地揭示了随焊激冷防止焊接热裂纹的机理及主要参数的影响规律 .研究表明 ,随焊激冷能够通过冷源作用区的冷却收缩造成对其前方处于BTR金属的横向挤压 ,推迟塑性拉伸应变的开始形成温度并减缓其发展速率 ,因而降低热裂纹倾向 ;采用较小的激冷距离有利于降低热裂纹倾向 ,在激冷距离较大时提高激冷功率仍有防止热裂纹的作用 ;加大外部拘束会在一定程度上削弱随焊激冷防止热裂纹的效果 .     

矿井集中降温系统末端空冷器布置方式及降温效果研究

阐述丁集煤矿的热害现状,介绍矿井集中降温系统末端空冷器的布置方式,分析各种空冷器布置方式的优缺点,并对其实际降温效果进行研究。结果表明,采用梯级供冷、串级供冷和局扇群供冷均可解决采掘工作面的热害问题,保护井下作业人员的身心健康,同时提高劳动效率。本研究对我国矿井降温技术的发展具有现实意义和指导作用。     

Mit Wärme Kälte erzeugen

A steam jet cooling plant Steam jet cooling plants with water as a medium to be cooled are preferably used to chill down to 0°C and below. Since most industrial enterprises have steam and cooling water supply nets already, steam jet cooling plants can be installed there quite easily. They are characterised by ‐ low investment costs, ‐ robust and simple construction, ‐ immediate response to changes of the required cooling capacity, ‐ very low maintenance and spare parts costs. Under certain conditions even hot water or waste steam (low‐pressure, vacuum or wet steam) can be used as a motive medium. A surplus of steam, perhaps, which occurs during the summer may be used for cooling purposes, easily. Below a steam jet cooling plant for a district cooling system is described which has been installed with the company Energieversorgung Gera GmbH (Gera, Germany). Since then, it has been worked successfully. The maximum chilling capacity is 600 kW (12°C/6°C).     

差压铸造薄壁铝硅合金铸件的位置效应

采用差压铸造工艺,研究垂直缝隙式浇注系统浇注的铝合金硅铸件不同位置的组织和力学性能变化.采用石英砂型、SiC砂型和冷铁,浇口处铸件的晶粒最细小,致密度高、力学性能最好;铸件冷端的组织和性能次之;位于两者之间的铸件的组织和性能最差.分析表明对于具有垂直缝隙式浇注系统,差压铸造凝固压力对金属的凝固作用具有位置效应,浇口处液态金属温度高,凝固时间长,凝固压力对浇口处金属的凝固作用显著;铸件冷端金属凝固时间短,凝固压力对该处金属的凝固作用不显著,铸型的冷却速度对铸件组织和性能的影响起显著作用.浇口处与冷端之间的金属液体的凝固受压力和冷却速度的影响小,铸件的晶粒尺寸最大、密度最小、性能最低.冷却速度提高,铸件的任意位置的组织和性能都相应得到提高.