制冷方面英文文献翻译

应用热工程

摘要:紧凑型翅片管蒸发器已被广泛应用于轻型商用制冷盒应用，这样的制冷系

统空间的约束，因此，热交换器（冷凝器和蒸发器）必须有大面积体积比。此外，这样的应用程序需要一个诱导在翅片表面的霜层的生长的冰点以下的蒸发温度，如果不使用适当的除霜策略，可能会阻止蒸发器除霜。彻底阻止蒸发器之前，霜层消耗热交换器的性能，通过增加一个额外的热阻和也由减少空气流量风机。彻底阻挡蒸发器之前，可以通过增加一个额外的热阻或者增加一个减少空气流量风机可以减少霜层消耗热交换器的性能。了解这些紧凑的热霜冻形成的途径换热器和风扇由霜堵塞影响的鲁棒设计方法是强制性的制冷系统以及设计更高效的除霜方法。在这项研究中的实验对翅片管蒸发器风扇特性考虑霜积进行了调查。为此，专门设计，建造和校准风洞设施进行闭环。实验测试了四种不同的执行（三波纹翅片和百叶窗翅片）蒸发器在不同的条件下，线圈。发现结霜速率随空气流量，过冷度和散热片的密度。霜冻积累的质量之间的相关关系，空气侧压降和冷却能力也被观察到。也有人指出，风机特性发挥在蒸发器的热性能的重要作用，表明结霜工况下的风扇蒸发器对设计必须作为一个耦合系统。此外，对于相同的操作条件下，该百叶窗翅片蒸发器均要比波浪翅片盘管结霜的影响更敏感。

2010爱思唯尔公司保留所有权利。

1、介绍

能源资源的使用效率是现代社会中的基本问题，不仅是由于其内在环境的吸引力，而且稳步增长的成本，鼓励的方式产生能量的变化，分配和消费。由于制冷部门负责全球消耗大量的能量，多数政府开展能源消费政策，以刺激高效制冷系统的发展。然而，开发的这样一类的制冷机组不仅依赖于系统的组件设计（例如，高效率的压缩机，防污冷凝器，无霜蒸发器），而且它们之间的一个适当的匹配。

中背压（MBP）轻型商用制冷设备通常运行蒸发温度接近10℃时，蒸发器盘管上的霜层的温度，有利于形成。由于换热器的性能的导热系数低，结霜层和减少风扇提供的空气流率的综合效果，累计蒸发器盘管上的霜会显着下降。在结霜的效果的总传热系数和工业蒸发器的空气侧压降的实验研究中，首次观察到这样的双重效果斯迪克[1]。然而，尽管它的重要性，蒸发器的结霜研究仍然潜伏了很多年，可以看出，在表1中，总结了在该领域的最有影响的出版物。

在20世纪90年代初，Rite和克劳福德[3]进行国内翅片管式换热器结霜条件下的实验研究，观察空气侧压降和总传热系数的增加，后者被解释的增加的传热表面和减少热管及散热片之间的接触电阻。后来，Bejan等人。 [5]也研究结霜工况条件下运行的制冷系统的性能。作者假定一个恒定的结霜速度，开/关控制策略，最大限度地减少了整个系统的能量消耗以考虑所用的除霜加热器的电功率，并确定一个最佳的。然而，上述研究没有考虑结霜的蒸发器和风扇提供的空气流率（见表1）之间的结合引起的非线性效应。

在填补这一空白的第一次尝试，下等人。[ 11 ]研究了结霜，除霜，以对百叶窗翅片扁管换热器在结霜过程和观察到的地方，由于空气的流量的减少也与百叶窗间隙桥接的总传热系数降低。作者认为，最初的空气压降增加每个除霜周期由于冷凝水滴滞留，随后重新霜后。虽然这项研究显示，对一些影响结霜现象的因素的重要信息，对风机的冷却能力，典型的轻型商用冰箱翅片管蒸发器提供具

体的调查（～1千瓦）仍在进行。因此这是本研究的主要焦点。

D.L.达席尔瓦等。 /工程热物理学报XXX（2010）1-8

命名

罗马

Awf 无霜蒸发器[m2] Cpa 恒压比热[Jkga-1K-1] h 空气焓[Jkga-1K-1]

L 潜热[Jkgs-1K-1]

m 空气质量流量[kgas-1] mf 结霜率[kgss-1]

Mf 积霜[kg]

p 气压[Pa]

q 蒸发器冷却容量[W] t 时间[s]

T 温度[oC]

Uh 焓的传热系数[Wm-2] K 修正电导[WK-1] 希腊

△变化[-]

Φ相对湿度[%]

ω比适度[kgskga-1]

下标

a干燥的空气

evap蒸发器

f霜

lat潜伏

m意思

s蒸汽

s，r饱和食盐水洗涤温度sen明智

sur周围

1入口

2出口

2.实验内容

2.1 实验装置

实验装置包括一个矩形的横截面闭环风洞设施和二次冷却剂制冷系统。前者是用来在蒸发器的入口控制空气的温度，湿度和流速，后者是设计蒸发器的表面温度。图1是实验装置示意图，分为利于空气流通的上部和进行测试的下部。在下部，空气首先流经6.35厘米的喷嘴（1），根据ASHRAE51[18]的标准用于测量空气流率的，最大误差为0.003立方米/秒。随后空气被一个线圈（2）冷却，由一个电加热器（3）重新加热和接水盘（4）重新加湿。所有这些由PID控制，以保证在进气口的测试部分中所需的心理过程的条件

在试验台的上部，空气温度，相对湿度和压力的测量是通过向上和向下流的蒸发（EVAP）。空气温度是通过9个T型热电偶（TT）的相互两个网格来测量的，其最大误差0.2℃。相对湿度是由两个电容式湿度传感器（HT）来测量的，最大误差为15%（相对湿度）。在蒸发器盘管的空气侧压降是通过一个压差传感器（PT）来测量的，最大误差为2.5Pa。霜冻生成速率和传热速率由准稳态的质量和能量平衡来间接测量的，误差分别为0.1Kg/h，80W。

蒸发器（EVAP）固定在一个木结构上，其中一个减振器将空气流到其前表面或一个位于下方的线圈的旁路（BP）开口。本装置保证结霜过程开始当其测试条件达到时。冷冻乙烯乙二醇 - 水溶液流过该线圈，以这样一种方式建立在蒸发器的表面温度，其入口和出口的最高温度之间的差异为3.5℃。

空气流量是由计算机驱动的可变速度控制离心风机（5）来控制的，风机的模拟性能特点通常发现在轻型商用制冷系统中。风机的仿真过程是如下一个反复过程，其收敛时，施加所需的空气流率和实际值之间的差异小于2%。图2显示了通过模拟离心式风机试验台，其压力与轴向风扇的特性。因此结霜测试可以用一个常量和变量的空气流率来测试。

表1

蒸发器盘管上的霜积在前人研究的总结。

作者年份产地参考申请方式风扇斯迪克1957 美国[1] 翅片管式实验没孔德普地奥尼尔1987 美国[2] 翅片管式数值（集中）没仪式和克劳福德1991 美国[3] 翅片管式实验没奥哥瓦等人1993 日本[4] 无霜实验没本杰等人1994 美国[5] 无霜理论没卡尔德等人2001 美国[6] 微通道实验没吉赫2002 韩国[7] 翅片管实验没陈等人2003 加拿大[8] 散热器数值（集中）有谢凯尔等2004 土耳其[9] 无霜数值（集中）没Tso等人2006 新加坡[10] 翅片管式数值（分布式）没夏等人2006 美国[11] 微通道数值（集中）没Aljuwaie 2006 美国[12] 工业蒸发器数值（分布式）有杨等人2006 韩国[13] 翅片管式数值（分布式）没Ngonda和希尔2007 南非[14] 翅片管式数值（分布式）没张和赫尔尼亚克2007 美国[15] 翅片管式实验没lenic等2009 克罗地亚[16] 翅片管式数值（分布式）没穆阿利姆等2010 美国[17] 微通道实验没

2.2 蒸发器样品

如图3所示为蒸发器的翅片圆管交叉流式热交换器。百叶窗和波状散热片是由一个厚度为0.2mm的铝合金制成。铜管外径为10mm，壁厚为1mm。蒸发器宽为320mm。高152mm，深45mm。该管布置为两个交错的行，每行有六个管。相邻两个管之间纵向和横向之间的间距分别是22mm和25mm。

2.3 数据处理

通过在蒸发器准稳定的质量，能量和力的平衡被处理来获得霜的形成率，总热传输速率和空气压降

m f 代表结霜速率[kg

s

s-1]，m空气流率[kgs-1]，ω湿度比[kg

s

kg

a

-1]，p空气压力[Pa]，

Cp，a恒压下空气比热[Jkg

a

-1K-1],T温度[K]，K经验修正电导[WK-1],L潜热

[Jkg

s -1K-1],q冷却能力[W]。计算累计霜质量，M

f

公式：

由于结合的质量和能量的传递依赖于焓差[19]，基于焓的总传热系数U

h

如下得来：

式中U

h 是总传热系数[Wm-2J-1kg

a

]，Awf是无霜的蒸发器表面面积[m2]，△hm是平

均空气焓差[Jkg

a

-1]，h1和h2分别是所示蒸发器入口和出口潮湿的空气焓

[Jkg

a -1]，hs，r1和hs，r2分别是食盐水进入和离开温度的饱和湿空气焓[Jkg

a

-1]。

2.4 测试计划

该测试的目的是要调查散热片的密度，空气温度和湿度的影响，蒸发器表面的温度和蒸发器空气压力下降下的空气流量，冷却能力和积霜质量。过冷度（即，露点之间的温度差进入的空气流和蒸发器的表面）为3.5，5.0，10.0和14.5℃下结合使用不同的空气流量和蒸发器的几何形状（即不同类型的散热器形状和密度）。表2总结了在测试条件下其覆盖范围内的轻型商用制冷的典型应用。实验一直进行到蒸发器的空气流量或总测试时间分别达到60m3/h或120min。

3.结果和讨论

图4显示了在风扇曲线1的情况下，蒸发器表面上积霜随时间的变化（见图2）。可以看出，前者的散热片密度和过冷积霜积累率的增加水平大于后者。另外，结霜累积率随着时间的推移会略有下降，尤其是在过冷度为10.0和14.5℃测试条件下，这是由于结霜表面温度和风扇提供的空气流率降低的缘故。

图5显示了静止图像拍摄的开始和结束35分钟的实验，其空气流量为

150m3/h，空气温度和湿度分别为10℃和50%，盐水进口样品温度为-10℃。图5B 显示了蒸发器自由流动面积的显著减少，对蒸发器上的热工水力性能有着较大的影响。应该指出的是所有的分析都使用了过冷这个参数的值，因为此参数汇集了

所有与独立变量（p，T

a ，ψ和T

evap

）有关的信息。

图6A示出了累计霜冻质量对空气侧压降的影响，可以看出，过冷度和散热片密度都可以增加空气压降。同样还可以观察到在低水平的过冷度下（即3.5℃）压降几乎保持不变，由于积霜在这些条件下的质量很小（见表2）。图6B显示出累计霜冻质量的影响和风扇提供空气流率下的空气压力的下降。值得注意的是，空气流速显着降低，特别是在过冷值为10.0和14.5℃时，此时在30—70分钟内可以观察到50%的变化，取决于散热片密度和过冷程度。同样可以看出，在相同过冷度下一个较大的散热片可以导致更大范围内空气流率的减少。

图7A示出了累计霜冻质量对蒸发器的冷却能力的影响。正如预期一样，热传递增加过冷度和散热片密度。同样可以看出，30分钟后的冷却能力为4.7鳍/厘米蒸发器，过冷值为14.5℃，降低了40%，在相同的过冷度下达到了与观察相似的3.2鳍/厘米蒸发器，从此时起，4.7鳍/厘米蒸发器的冷却能力超过了3.2鳍/厘米蒸发器。图7A还显示出实验之间常量和空气流速变量之间的比较（表2中测试1和3）。应该指出的是在一个恒定的空气流速下，在80分钟后测试，蒸发器的制冷能力下降了15%。这些数字表明，相比层霜，空气流率的降低对额外热电阻蒸发器的性能有较大的影响。总传热系数和时间的函数绘于图7B中，它表明，对比于高的过冷度条件下，低过冷度下观察到Uh值几乎保持不变。

为了分析散热片对蒸发器上热敏液压的影响，测试时在相同的两个蒸发器（波浪形散热片，2.2鳍/厘米）的两个过冷度（10和14.5℃）下，使用的散热曲线见图2（测试10-13）。图8可以看出散热片Ⅱ诱导结霜速率更高，在测试结束时增加了50g霜，除了结霜的额外质量。图8B显示散热片Ⅱ在整个测试过程中可以提供更高的空气流速，尽管由散热片Ⅰ和散热片Ⅱ提供的空气流率下降不同随时间增加散热片Ⅱ会诱导更快的蒸发器堵塞。图9显示的是冷却能力随时间的变化（图9A）和相同测试条件下的总热传导系数（图9B）。在相同过冷度下，散热片Ⅱ的制冷能力至少高于散热片Ⅰ的20%。类似的现象在整体热焓系数中被发现。

散热片（百叶窗式或波纹状）对蒸发器的性能的影响用两个2.2鳍/厘米的蒸发器在相同结霜条件下（测试10,11,14和15，表2）进行评估。图10A显示霜冻质量随时间的积累，可以看出，在相同的过冷度下，这两种类型的散热片有着相似的结果。然而如图10B所示，百叶窗式翅式蒸发器在空气流速上经历了一个更快的下降由于较高的霜堵塞了空气流的通过。此外，图11示出冷却能力随时间的变化，可以观察到百叶窗式散热片在开始的测试中有稍微较好的散热性能，此时没有重大结霜在散热片线圈上。然而，这样的行为在40分钟和60分钟，过冷度分别为14.5和10.0℃时被反转，可以被解释为散热片提供的空气流率减少来解释，见图10A。

图5：散热片结霜前（a）和结霜后（b）的可视图

图6：不同散热器间距和过冷度的蒸发器空气侧压降（A）和空气流速（B）

图7：不同散热片间距和过冷度下制冷能力（A）和总传热系数(B)

图8：不同散热片和过冷度下累计霜质量（A）和空气流量（B）

图9：不同散热片和过冷度下制冷能力（A）和总传热系数（B）

4.总结和结论

一个特建的实验设施被专门设计和建造为了调查积霜对管片式蒸发器盘管的热工水力性能的影响。测试设备包括一个封闭的可控制回路风洞和食盐水器皿和空气流动性以及模拟产品散热片特性设备。实验是两个翅式换热器在不同的蒸发和入口空气温度以及相对湿度下进行的。可以观察到，霜积累速率随着空气流率、过冷度和散热片密度的增加而增加。严格的积霜质量，空气侧压降和冷却能力之间的关系也可以观察到。此外，它还表明空气流速的减少影响蒸发器的冷却能力当超过霜层额外热绝缘时。该结果还表明用于结霜条件的散热片和蒸发器的设计不能脱离关系。

结果表明，结霜条件下散热器蒸发器必须被设计为一个耦合系统中，为了使原有制冷能力保持更长时间，需增加连续除霜过程时间和提高整个系统的热性能。最后还观察到在相同的操作条件下，百叶窗式翅片蒸发器与波状翅片蒸发器相比有较低的冷却能力。这样的行为是由于空气流的过快减少和额外的压降被引入而引起的。

致谢

这项研究是在POLO实验室，国家批准号573581/2008-8（国家科学和资助的制冷技术和热物理）CNPq机构中进行的。恩布拉科S.A.的财政支持是不可忽略的，作者还感谢巴雷塔·朱利亚小姐和埃利亚斯·伦先生和卢卡斯的Sassi，所有本科生机械工程的学生，为他们在实验中提出宝贵意见。

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[5] A. Bejan, J.V.C. Vargas, J.S. Lim, When to defrost a refrigerator, and when toremove the scale from the heat exchanger of a power plant, International Journal of Heat and Mass Transfer 37 (1994) 523e532. [6] D.M. Carlson, P.S. Hrnjak, C.W. Bullard, Deposition, distribution, and effects offrost on a multi-row heat exchanger performance, Technical Report, ACRC,University of Illinois at Urbana-Champaign, USA, 2001. [7] S. Jhee, K. Lee, W. Kim, Effect of surface treatments on the frosting/defrosting behavior of a fin-tube heat exchanger, International Journal of Refrigeration 25 (2002) 1047e1053.

[8] H. Chen, L. Thomas, R.W. Besant, Fan supplied heat exchanger fin performance under frosting conditions, International Journal of Refrigeration 26 (2003) 140e149.

[9] D. Seker, H. Karatas, N. Egrican, Frost formation on fin-and-tube heat exchangers. Part I e Modeling of frost formation on fin-and-tube heat exchangers, International Journal of Refrigeration 27 (2004) 367e374.

[10] C.P. Tso, Y.C. Cheng, A.C.K. Lai, Dynamic behavior of a direct expansion evaporator under frosting condition. Part I. Distributed model, International Journal of Refrigeration 29 (2006) 611e623.

[11] Y. Xia, Y. Zhong, P.S. Hrnjak, A.M. Jacobi, Frost, defrost, and refrost and its impact on the air-side thermalehydraulic performance of louvered-fin, flat-tube heat exchangers, International Journal of Refrigeration 29 (2006) 1066e1079.

[12] N.F. Aljuwayhel, Numerical and experimental study of the influence of frost formation and defrosting on the performance of industrial evaporator coils, PhD Thesis, University of Wisconsin-Madison, USA, 2006.

[13] D. Yang, K. Lee, S. Song, Fin spacing optimization of a fin-tube heat exchanger under frosting conditions, International Journal of Heat and Mass Transfer 49 (2006) 2619e2625.

[14] T.N. Ngonda, T.J. Sheer, Frost formation on cooling coil in supersaturated supply air, International Congress of Refrigeration, Beijing, 2007.

[15] P. Zhang, P.S. Hrnjak, Air-side performance evaluation of three types of heat exchangers in dry, wet and periodic frosting conditions, International Journal of Refrigeration 32 (2009) 911e921.

[16] K. Lenic, A. Trp, B. Frankovic, Prediction of an effective cooling output of the fin-and-tube heat exchanger under frosting conditions, Applied Thermal Engineering 29 (2009) 2534e2543

[17] E. Moallen, L. Cremaschi, D.E. Fischer, Experimental investigation of frost growth on microchannel heat exchangers, in: 13th Int. Refrigeration Conference at Purdue, West Lafayette, IN, USA, Paper 2416.

[18] ASHRAE Standard 51, Laboratory Methods of Testing Fans for Aerodynamic Performance Rating. American Society of Heating, Refrigeration and Air Conditioning Engineers, Atlanta, GA, USA, 1999.

[19] J.L. Threlkeld, T.H. Kuehn, J.W. Ramsey, Thermal Environmental Engineering,thirrd ed. Prentice-Hall, USA, 1998.

[20] C.J.L. Hermes, R.O. Piucco, J.R. Barbosa Jr., C. Melo, A study of frost growth and densification on flat surfaces, Experimental Thermal and Fluid Science 33 (2009) 371e379

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智能家居医疗保健中英文对照外文翻译文献 (文档含英文原文和中文翻译) 原文： Foreign Literature Increasing an individual’s quality of life via their intelligent home The hypothesis of this project is: can an individual’s quality of life be increased by integrating “intelligent technology”into their home environment. This hypothesis is very broad, and hence the researchers will investigate it with regard to various, potentially over-lapping, sub-sections of the population. In particular, the project will focus on sub-sections with health-care needs, because it is believed that these sub-sections will receive the greatest benefit from this enhanced approach to housing. Two research questions flow from this hypothesis: what are the health-care issues that could be improved via “intelligent housing”, and what are the technological issues needing to be solved to allow “intelligent housing”to be constructed?

机械专业中英文对照翻译大全.

机械专业英语词汇中英文对照翻译一览表 陶瓷ceramics 合成纤维synthetic fibre 电化学腐蚀electrochemical corrosion 车架automotive chassis 悬架suspension 转向器redirector 变速器speed changer 板料冲压sheet metal parts 孔加工spot facing machining 车间workshop 工程技术人员engineer 气动夹紧pneuma lock 数学模型mathematical model 画法几何descriptive geometry 机械制图Mechanical drawing 投影projection 视图view 剖视图profile chart 标准件standard component 零件图part drawing 装配图assembly drawing

尺寸标注size marking 技术要求technical requirements 刚度rigidity 内力internal force 位移displacement 截面section 疲劳极限fatigue limit 断裂fracture 塑性变形plastic distortion 脆性材料brittleness material 刚度准则rigidity criterion 垫圈washer 垫片spacer 直齿圆柱齿轮straight toothed spur gear 斜齿圆柱齿轮helical-spur gear 直齿锥齿轮straight bevel gear 运动简图kinematic sketch 齿轮齿条pinion and rack 蜗杆蜗轮worm and worm gear 虚约束passive constraint 曲柄crank 摇杆racker

java毕业论文外文文献翻译

Advantages of Managed Code Microsoft intermediate language shares with Java byte code the idea that it is a low-level language witha simple syntax , which can be very quickly translated intonative machine code. Having this well-defined universal syntax for code has significant advantages. Platform independence First, it means that the same file containing byte code instructions can be placed on any platform; atruntime the final stage of compilation can then be easily accomplished so that the code will run on thatparticular platform. In other words, by compiling to IL we obtain platform independence for .NET, inmuch the same way as compiling to Java byte code gives Java platform independence. Performance improvement IL is actually a bit more ambitious than Java bytecode. IL is always Just-In-Time compiled (known as JIT), whereas Java byte code was ofteninterpreted. One of the disadvantages of Java was that, on execution, the process of translating from Javabyte code to native executable resulted in a loss of performance. Instead of compiling the entire application in one go (which could lead to a slow start-up time), the JITcompiler simply compiles each portion of code as it is called (just-in-time). When code has been compiled.once, the resultant native executable is stored until the application exits, so that it does not need to berecompiled the next time that portion of code is run. Microsoft argues that this process is more efficientthan compiling the entire application code at the start, because of the likelihood that large portions of anyapplication code will not actually be executed in any given run. Using the JIT compiler, such code willnever be compiled.