论文中英文摘要
完整英文摘要

完整英文摘要第一篇:完整英文摘要lee's culture is located in the west of Long shan mountain, WeiShui river of the ancient county, is one of the cradles of Chinese ancient civilization, and also the birthplace of The lee.With Dunhuang culture, Tianshui fuxi culture, LaBuLengSi Tibetan Buddhism culture is one of four culture of Gansu province.But at present, the cultural development of West gansu is lagging behind, a lot of development and utilization of resources is difficult to get, it has to do withWest gansu geographical position relatively closed, human resources development has a close relationship.Lee's culture as an important form about culture, also suffered a bottleneck in its development, lee's cultural history and contemporary development not well together, especially in the promotion and development of invested is not enough, lead to lee's culture has been difficult to familiar to the general public.Local economic backward culture is difficult to promote the development process.Fully realize the importance of West gansu lee culture, reasonable and effective development of lee's culture, make its internal value have spread wider, deeper reach to culture to promote economic and cultural development dual goal.Cultural characteristicscountermeasuresThe economicdevelopment第二篇:摘要英文摘要温度是生产过程中常见和重要的物理参数。
论文写作中的英文摘要范例

论文写作中的英文摘要范例英文摘要(Abstract)是论文写作中必不可少的一部分,其作用是概括出论文的主要内容和结论,帮助读者迅速了解论文的核心观点。
本文将提供一篇关于论文写作中英文摘要的范例,以供参考。
AbstractWith the increasing globalization of academic research, it has become essential for scholars to effectively communicate their work to a wider audience. One crucial element in this process is the abstract, which summarizes the main points and findings of a research paper. In this article, we will provide an example of an English abstract for a research paper, demonstrating key elements and tips for writing an effective abstract.IntroductionThe abstract serves as a brief overview of a research paper, allowing readers to quickly grasp the purpose, methodology, and outcomes of the study. It should be concise yet informative, providing enough information to engage the reader while remaining within a specified word limit.Main BodyI. Purpose and BackgroundThe first element of an abstract is a clear statement of the research paper's purpose and its background. It should outline the rationale for the study, highlighting any research gaps or unanswered questions in the field. For example:This research aims to investigate the effects of climate change on coastal ecosystems, with a focus on marine biodiversity and coral reef health. Given the increasing threats to these ecosystems, understanding the potential impacts of climate change is crucial for effective conservation strategies.II. MethodologyThe abstract should briefly describe the methodology employed in the research. This can include the study design, data collection methods, and analytical approaches. However, detailed technical information should be avoided. For example:A combination of field surveys, laboratory experiments, and statistical analyses were conducted to assess the long-term effects of temperature increase and ocean acidification on coral reefs. Data on species diversity, abundance, and health were collected from various reefs in the Caribbean region.III. ResultsThe abstract should highlight the key findings of the research. It should summarize the outcomes and conclusions derived from the data analysis. However, specific data or numerical results should be avoided, focusing instead on general trends and significant discoveries. For example:Our study revealed a significant decline in coral species diversity and overall health in response to increased water temperatures and ocean acidification. Furthermore, we found a decrease in the abundance of commercially important fish species, indicating potential impacts on local communities dependent on coral reef resources.IV. Implications and ConclusionThe abstract should conclude with a discussion of the broader implications of the research and its significance. It should provide a concise statement summarizing the main contributions of the study to the field and any recommendations for future research or policy implications. For example:These findings highlight the urgent need for immediate actions to mitigate the effects of climate change on coastal ecosystems. Implementing measures to reduce greenhouse gas emissions and establishing marine protected areas can help safeguard marine biodiversity and protect the livelihoods of communities dependent on coral reef resources.ConclusionIn conclusion, writing an effective English abstract is crucial for communicating the key points and contributions of a research paper. By providing a clear purpose, concise methodology, major findings, and broader implications, the abstract serves as a concise summary of the research work, enticing readers to delve deeper into the full paper. By following the guidelines and structure provided in this example abstract, researchers can enhance their chances of effectively conveying their research to a global audience.。
毕业论文标题中英文摘要关键词和目录的格式

毕业设计(论文)新民本主义:传统民本思想与现代民主理念的契合(字体:黑体小一)专业年级学生学号学生姓名指导老师评阅人二○○年月中国·南京摘要(“摘要”两字的字体为黑体三号,居中。
)正文字体均为:宋体小四号,行距为倍(不低于400字)关键词:民本;民主;新民本主义(“关键词”三字字体为黑体,内容(3-5)个,宋体小四号。
各关键词之间用;)注意:摘要和关键词只能单独一页.Abstract(“Abstract”一词用Times New Roman字体三号,加黑,居中。
)Thought of people as the center is the marrow of our traditional culture and the core of the theory of managing state affairs. It germinates in the early state of antiquity society and is based on patriarchal clan system. It is also a kind of value seeking for the realization of the ethic reason and moral justice. Its basic thinking is that the monarch is defined by people and conversely people are defined by the monarch. At first appearance, its purpose is to value people’s suffering,fate and interest on the ruler’s position. However, its real intention is to fool the people so as to strengthen and consolidate the ruler’s rule. The theory of “people-oriented concept” includes nine topics such as “the theory of people is being the root of the monarch’s rule”, “the theory of people is being more valuable than the monarch”, “the theory of the monarch is being people’s servant”and so on. People –oriented means “value the people ”in essence, which sees “people”as its foundation of politics rule, ranking official, and administration.(正文字体为:Times New Roman字体,小四号,且行距为单倍或倍。
论文中英文摘要格式

论文中英文摘要格式附件2作者姓名:顾振华论文题目:2,3-联烯酸(酰胺)与联烯和炔烃的偶联环化反应研究作者简介::顾振华,男,1979年02月出生,2002年09月师从于中国科学院上海有机化学研究所麻生明教授,于2007年7月获博士学位。
中文摘要联烯是一类含有1,2-丙二烯官能团的化合物。
在联烯的三个碳原子中,末端的两个sp2杂化的碳原子以剩下的未杂化的p轨道与中间的sp杂化的碳原子的两个互相垂直的p-轨道交盖形成两个互相垂直的π轨道。
当联烯末端的同一碳原子上的取代基两两不同时,联烯则具有轴手性,其构型可通过Cahn-Ingold-Prelog规则判定。
联烯化合物独特的反应性一方面来自这种独特的互相垂直交盖π-轨道,另一方面来自联烯末端的两个碳原子(四个取代基)对不同取代基的装载能力。
通过对底物及反应条件的调控,反应可以选择性的发生在联烯的三个不同的碳原子上。
由于其独特的结构及反应性,联烯在天然产物的合成中也有比较广泛地应用。
近年来越来越多的含联烯结构的天然产物被分离和鉴定,到目前为止已有约150个,这也极大地推动了联烯化学的发展。
我们小组在官能化的联烯的环化反应方面也作了一些研究。
最近我们小组发现并发展了官能化联烯的双分子氧化偶联反应,该反应能有效的一步构建双环化合物。
基于这些发现,我的工作就是设计和发展联烯与联烯、联烯与炔烃的偶联环化反应。
主要包括以下三大部分:第一部分:2,3-联烯酸(酰胺)与联烯的偶联环化反应1.我们研究了2,3-联烯酸双分子氧化偶联反应。
在研究过程中我们发展了三套氧化体系(a) n-C3H7I + O2, (b) KI + O2, (c) 苯醌来实现钯物种的催化循环,并且还研究了在这三套氧化体系下的取代基效应。
2.在实现了2,3-联烯酸自身双分子氧化偶联反应之后我们又研究了2,3-联烯酰胺与1,2-联烯基酮的交叉偶联反应。
根据我们小组以前的研究2,3-联烯酰胺有两种环化方式:即氧进攻生成Furanimine结构的化合物,或氮进攻生成内酰胺的产物。
(论文中英文摘要格式)

(论文中英文摘要格式)作者姓名:肖伟烈论文题目:四种药用植物的化学成分和生物活性研究作者简介::肖伟烈,男, 1976年12月出生,于2002年9月师从中国科学院昆明植物研究所孙汉董院士攻读植物化学博士学位,并于2005年7月获博士学位。
中文摘要本论文由五章组成。
第一章论述了狭叶五味子化学成分及生物活性的研究。
第二章为红花五味子茎叶和果实的化学成分及生物活性的研究。
第三章介绍法落海化学成分及生物活性的研究。
第四章论述了白云花化学成分及生物活性的研究。
论文第五章综述了1999年到2004年间发表的新环阿尔廷三萜类化合物。
通过波谱分析及晶体X-衍射等手段,从上述四种植物中共分离鉴定了129个化合物,32个为新化合物。
已鉴定的化合物类型涉及三萜、三萜皂甙、黄酮、黄酮苷、香豆素、香豆素苷、木脂素、甾体及环烯醚萜苷等化合物类型。
新化合物有三萜、香豆素苷、环烯醚萜、木酯素。
首次发现了一种新奇的五降三萜、一种带有螺环和烯醇式结构片段三萜化合物等结构新奇的降三萜化合物,同时还分离得到一种通过分子间重排而成的环烯醚萜二聚体苷类化合物。
对分离得到的部分化合物进行了抗HIV活性和抗血小板聚集活性筛选的研究发现,部分化合物具有抗HIV活性,5个化合物的抗HIV选择指数(SI)大于43。
这为治疗艾滋病药物的研究拓宽了思路,对于进一步进行结构修饰与改造、半合成或全合成,开发成具有自主知识产权的创新新药具有重要意义。
新奇结构的发现,不仅丰富了天然产物化学的内容,且为进一步合理开发利用云南的传统药用植物资源提供了新的化学物质基础和科学依据。
1 2 3 45 6 7 89 10 11 12图-1 结构新奇的化合物第一章狭叶五味子的化学成分和生物活性研究狭叶五味子(Schisandra lancifolia (Rehd. et Wils.) A. C. Smith)。
全株药用,味微苦、涩、性温,有止血接骨、去淤消肿之功效,用于跌打损伤、骨折、外伤出血等症。
中英文论文写作(摘要)

1 基本特性 2 时态 3 语态 4 语法修辞 5 一个典型示例 6 化学常用句式
2 时态
以一般现在时为主, 也使用一般过去时和 现在完成时 从理论上讲: 说法一: 一般现在时
通过科 学实验取得的 研究结果、结 论,揭示自然 界的客观规律 一般过去时
Objective 动词不定式开头 To investigate … To study … To explore … To examine … To determine … To report … To review … 使用第一人称时,用凡指的we, the author, the authors ,不用I。 如: In this paper we conclude …
Result: The contents of the components of midecamyc A1 and leucomycin A6 was 30%~ 50% and 10%~20% respectively, the contents of the rest components w lower, different manufactures produces have differ components. Conclution: To revise the specificati meleumycin for quality control.
指示性文摘(indicative abstract)
This type of abstract is designed to ind the subject of a paper, making it easy fo potential readers to decide whether to r the paper.
科技论文的中英文摘要写作规范

科技论文的中英文摘要写作规范1.摘要是报告、论文的内容不加注释和评论的简短陈述;2.报告、论文一般均应有摘要,为了国际交流,还应有外文(多用英文)摘要;3.摘要应具有独立性和自含性,即不阅读报告、论文的全文,就能获得必要的信息。
摘要中有数据、有结论,是一篇完整的短文,可以独立使用,可以引用,可以用于工艺推广。
摘要的内容应包含与报告、论文同等量的主要信息,供读者确定有无必要阅读全文,也供文摘等二次文献采用。
摘要一般应说明研究工作的目的、实验方法、结果和最终结论等,而重点是结果和结论。
4.中文摘要一般不宜超过200~300字,外文摘要不宜超过250个实词。
如遇特殊需要字数可以略多(为了扩大国际影响,英文摘要要尽量写长一些,可不与中文摘要一一对应。
——编辑部注)。
5.除了实在无变通办法可用以外,摘要中不用图、表、化学结构式、非公知公用的符号和术语。
6.报告、论文的摘要可以用另页置于题名页之后,学术论文的摘要一般置于题名和作者之后、正文之前。
7.学位论文为了评审,学术论文为了参加学术会议,可按要求写成变异本式的摘要。
,不受字数规定的限制。
——引自《中华人民共和国国家标准》科学技术报告、学位论文和学术论文的编写格式。
科技论文的编写格式科技论文是科技发展及现代化建设的重要科技信息源,是记录人类科技进步的历史性文件。
什么是科技论文?它与一般的科技文章有什么不同?怎样写好科技论文?这些都是广大读者感兴趣的问题。
因此,利用“读者专栏”栏目,连续刊登“科技论文的编写格式”(引自《科学技术期刊编辑教程》,以期进一步提高科技论文的整体水平。
1.什么是科技论文⑴科技论文的基本特征什么是科技论文?目前还没有完全统一的认识,但是作为科技期刊刊载的客体,不妨可以认为:在认识和改造客观世界的过程中,通过足够的,可以重复其实验(或存在某种类似做法的潜力),使他人得以评价和信服的素材论证,首先揭示出事物及其真谛,并发表于正式科技期刊或其他得到学术界正式认可形式的叙述文件可统称为科技论文。
2019年英文摘要的论文范文

英文摘要的论文范文有了英文摘要便方便了国际间的交流,取长补短,共同进步。
下面准备了几篇英文摘要的论文范文,欢迎欣赏!英文摘要的论文范文一Fortheviolationoflegitimaterightsandinterestsofconsumersava rietyofoffenses,howtoprovideforthecorrespondinglegalrespons ibilitiesandhowthelegalliabilitysystemreflectedthespecialpr otectionofconsumersshouldbe"ConsumerProtectionLaw"keysolved alegalissue.Tosolvethislegalproblem,itisnecessarytofurtherestablishareg ulatedmarketoperatingordertoprotectlegitimateinterestsofcon sumersandimprovingthelegalliabilitysystem.Ontheonehandistoestablishalegalsystemtheconceptofprotection ofconsumers;theotherhand,istoimproveconsumerprotectionlegalliabilitysys tem.对于侵犯消费者合法权益的各种违法行为,如何规定相应的法律责任以及在法律责任制度中如何体现对消费者的特别保护,应是《消费者权益保护法》重点解决好的一个法律问题。
要解决好这一法律性问题,就必须进一步建立起规范的市场经营秩序和完善保护消费者合法权益的法律责任制度。
一方面是建立消费者的法律体系保护观念;另一方面是完善消费者权益保护的法律责任制度。
英文摘要的论文范文二Titaniumore,electedfrommagiteorTitanmagite,iswidelyusedasth erawmaterialintheproductionoftitaniumdioxide.Titaniumqualit yanditsyieldconstraintsisoftenthebottleneckinthetitaniumind ustry.Thus,wecannotblindlyconsumealargeamountofcapitaltomaintaino rimproveitsqualityandyield.Thispapermakesanattempttoexplore sandoptimizethedevelopmentofthetitaniumindustry,throughinsi deandoutsideobservationandassociation.Inthispaper,flotation testsareconductedtoparetheoriginalpulptitaniumorewithPolyac rylamideandthatwithoutontheconcentrategradeyieldoftitaniumc oncentrates.Inthisprocess,theconsumptionofdrugs,therecoveryrateof,equip mentutilization,theamountandcostofpolyacrylamide(PAM)areall consideredtodeterminewhetheritisaptimizationprogramtoaddPol yacrylamidetotheoriginalflotationpulpoftitaniumore.Finally,wereachaconclusionthroughrelevantdata.Intheexperime ntalprocess,inprinciple,wedonotchangetheoriginalflotationprocessandtherelevantparam eters.Keywords:Titaniumore;Flotation;Polyacrylamide;quality;yield 英文摘要的论文范文三【ABSTRACT】Withthedeepeningoftheglobalization,newshasbeeanimportantpar tofinformationmunicationbetweendifferentcountries.WhetherEnglishnewstranslationisaccurateornotmaydirectlyaffe ctthequalityofourmunicationwithothercountries.InEnglishnews reportdiscourse,theuseofmetaphorexpressionsbeemoreandmore.DuetoEnglishnewsandotherstylisticdifferences,aswellastheEng lishandChineselanguages,ethnicdifferencesinideologyinthepro cessofcross-culturalmunication,makethetranslationofEnglishn ews,especiallyEnglishnewstranslationofmetaphorputforwardgreatch allengetotranslators.SohowtotranslatethemetaphorintheEnglis hnewsisthemutualconcernproblemfortranslationtheoristsandpra ctitionerstodiscuss,therefore,thispaperattemptstofromtheperspectiveofNida'sfunctionalequi valencetheorytodiscussthetranslationofmetaphorinEnglishnews .TheapplicationofmetaphorinEnglishnewsmakeseventsmoredistinc tandvivid,andalsomakeiteasierforEnglishreaderstoprehendandu nderstandthenewscontents.However,duetothedifferencesinEnglishandChineselanguages,the useofmetaphorsinEnglishnewsincreasesthedifficultyoftranslat ion.ThisarticleattemptsfromtheperspectiveofNida'sfunctionalequivalencetheorytodiscussthetranslationofmetaphorinEnglish news,inordertomakeChinesereadersbetterunderstandthesameresponsea ndsenseofbeautyandmeaningofmetaphorsinEnglishnewsastheorigi nalreaders.metaphorRhetoricisnotsimpleoftranslationintoChineseinEnglis hnewsfromtheliteraltransformation,althoughsomerhetoricorare totallythesameinformandcontent,whilethisisjustafew.ThereareculturaldifferencesinEnglishandChineselanguages,inf luencedbydifferentcultures.People'swayofthinkingandexpressi onhavedifferencesinevitably.Whenthetranslatorshouldfirstlyc onsciouslypondertheintentionoftheauthor,digthedeepmeaninghiddenbehindthemetaphorrhetoricofbackgroun d.Underthefunctionalequivalencetheoryregardthetranslatorast heguidance,conformtothelanguagehabitsofthetargetlanguagerea ders,makeChinesereaderscanbetterunderstandthetranslationofm etaphorinEnglishnews.KEYWORD:Englishnews;metaphor;functionalequivalencetheory;translation【中文摘要】随着全球化的深入,新闻成为不同国家之间交流的重要部分。
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附件2论文中英文摘要作者姓名:陶于兵论文题目:CO2家用空调系统实验研究及换热器强化换热数值模拟作者简介:陶于兵,男,1979年11月出生,2003年9月师从于西安交通大学何雅玲教授,攻读硕博连读博士学位,于2008年6月获博士学位。
中文摘要近年来全球环境与能源问题日益严重,臭氧层破坏、温室效应以及能源危机已成为人类面临的主要挑战。
现有制冷空调等工业大量使用的氯氟烃类制冷工质,不仅会对臭氧层造成破坏,而且它们本身也是一种温室气体。
积极寻找制冷剂的替代工质,已成为目前制冷工业迫在眉睫的任务,CO2以其良好的热物性和对环境的无害性,已逐渐引起了各界的广泛关注。
另一方面,随着能源需求与日俱增、化石能源的大量消耗,排放了大量的温室气体,使得大气层的温室效应日益显著,人类正面临着全球能源日益枯竭和环境污染日益严重的问题,如何有效利用能源和保护生态环境是各国面临的重大课题。
因此,对在各领域大量应用的换热设备,进行强化换热及节能减阻研究显得至关重要。
本文针对国际上普遍关注的制冷工质替代及换热器强化换热、节能减阻问题,开展实验及理论研究。
实验方面,搭建了国内首台CO2家用空调系统性能测试实验台,对系统的COP 以及工质在换热器内的流动与换热特性随运行工况的变化规律进行了实验研究,探讨了提高系统性能的可靠方案;对带有内部回热器的CO2跨临界循环的节流损失及其主要影响因素,节流损失对系统COP 的影响进行了实验分析,指出了减小系统节流损失、提高系统性能的可靠途径。
理论方面,提出了适体坐标和块结构化相结合的复合网格生成方法,自行开发了三维适体坐标下的网格生成程序及SIMPLE算法程序,并运用该程序对工业领域及空调系统常用的翅片管换热器进行了大量数值模拟研究,分析了几何参数对波纹翅片管换热器的总体换热及阻力性能、翅片效率等的影响规律,并从场协同原理的角度对研究结果进行了合理解释。
同时,考察了平直翅片和波纹翅片表面的局部换热系数和翅片效率分布情况,并在此基础上进行了新型高效换热器的设计开发。
具体内容及结论如下:在CO2家用空调系统实验研究方面:(1)搭建了国内首台CO2家用空调系统性能测试实验台。
目前国际上,CO2作为天然制冷剂,已经在汽车空调、热水热泵及商业制冷等系统得到了成功应用,然而在家用空调方面还处在实验探讨阶段。
为了促进CO2制冷剂在家用空调系统的应用,本文考虑到CO2跨临界循环的高压侧压力非常高(7.0-12.0MPa)存在爆炸及容易泄露等问题,自行设计了实验系统方案,搭建了系统性能测试实验台,系统的设计方案及实验结果的精度和可靠性得到了日方合作伙伴详细验证及充分肯定。
在实验台上,分析了家用空调系统的工况参数对蒸发器和气体冷却器内部的流动和换热性能以及整个系统的总体性能的影响,实验结果发现,CO2家用空调系统的COP通常在2-3之间,略低于常规空调系统;气体冷却器的冷却效果是影响系统COP的主要因素,因此,强化冷却器的冷却效果是提高系统COP的有效手段;通过对循环进行优化、对冷却器采取强化换热措施可以使CO2系统的COP达到与常规空调系统相当的水平,从而证明了CO2天然制冷剂用于家用空调系统的可行性。
(2)分析了带有内部回热器的CO2跨临界循环的节流损失、节流损失对COP 的影响、影响节流损失的主要因素。
结果表明,内部回热器可以在很大程度上减小节流损失,然而带有内部回热器的跨临界循环,节流过程中仍然有5%的冷量损失,并造成系统COP减小近20%;进一步对影响节流损失的主要因素进行了分析研究,发现冷却器的冷却效果是影响节流损失的主要因素,冷却效果越好,节流损失越小,系统COP越高。
在换热器的强化换热及节能减阻性能研究方面:(3)提出了适体坐标和块结构化相结合的复合网格生成方法,自行开发了三维适体坐标下的网格生成程序及基于SIMPLE算法的数值模拟程序。
目前空调领域大量使用的都是波纹翅片管换热器,波纹翅片管换热器翅片表面之间是波纹形通道,另外还有管子的存在,结构非常复杂,网格生成困难,因此对其三维数值模拟研究迟迟未能展开。
本文提出了适体坐标和块结构化相结合的复合网格生成方法,开发了适体坐标下的网格生成程序和基于SIMPLE 算法的流动换热过程的三维数值模拟程序,所开发的程序可用于三维复杂区域的网格生成及流动与换热问题的数值求解,可以获得换热区域的总体换热及阻力性能,以及局部换热系数、局部温度场、流场的分布特性,并在其基础上对换热设备表面的形状和尺寸进行优化,从而实现换热设备的高效强化换热和节能减阻设计。
而且该模拟程序可以有效处理计算区域中同时存在流体和固体的流固耦合问题。
(4)基于自行开发的三维适体坐标下网格生成程序及SIMPLE算法程序,对三角形波纹翅片管换热器空气侧层流流动与换热特性进行了三维数值模拟研究。
重点考查了空气流动的雷诺数、翅片间距、翅片波纹倾角、管排数对流动与换热性能的影响规律,并从场协同角度分析讨论了这些参数的改变引起对流换热效果强化或恶化的物理本质。
研究结果表明,随流速增加、波纹倾角增加、翅片间距减小、管排数减小,换热器的换热特性得到强化,与此同时阻力损失也增加。
基于场协同原理,建立了单位体积换热量和全场平均协同角之间的对应变化关系。
采用之,对波纹翅片圆管及椭圆管换热器的换热特性随几何参数的变化关系给予了合理解释,使场协同原理可以更方便地应用于指导换热器结构的优化设计。
(5)分析了波纹翅片的翅片效率及翅片表面平均温度随雷诺数、波纹翅片倾角、翅片间距、翅片厚度及横向管间距的变化规律。
结果表明,随着雷诺数、波纹倾角、翅片间距、横向管间距的增加以及翅片厚度的减小,翅片表面温度逐渐降低,翅片效率逐渐减小;针对文献中常用的忽略翅片效率及翅片厚度的等温模型假设,指出在翅片材料的导热系数较高,空气流速相对较小的情况下,几何参数对翅片效率的影响较低,因此在精度要求不高的条件下,可以采用忽略翅片效率的等温模型;但是翅片厚度对换热及阻力性能的影响较大,在翅片厚度和翅片间距的比值不是很小的情况下,应该考虑翅片厚度的影响。
(6)进一步考察了波纹翅片表面的局部换热系数及局部翅片效率分布,获得了节能减阻型换热器的设计原理。
波纹翅片管换热器由于结构复杂,三维数值模拟工作开展较少,特别是波纹翅片表面局部换热系数及局部翅片效率分布的研究尚未见报道,而这些局部参数又是设计高效节能型换热器所必需的,因此,开展这方面研究非常必要。
本文采用数值模拟的方法获得了波纹翅片表面的局部换热系数及局部翅片效率的分布特性。
结果表明,局部换热系数沿空气流动方向逐渐减小;在波峰和波谷的位置,由于波峰破坏边界层,波谷处存在回流涡,局部换热系数的变化曲线出现波动;流速越高、波纹倾角越大,波动越明显;局部翅片效率沿流动方向逐渐增加,其分布特性主要依赖于翅片表面的温度分布。
获得了节能减阻型换热器的设计原理:在流速较低时,翅片管换热器的对流换热主要发生在入口区域,出口部分的波纹对换热的强化很小,却极大地增加了阻力损失,因此适当增加波纹翅片管换热器入口区域的翅片换热面积及波纹倾角,减小出口部分的换热面积及波纹倾角,可以达到强化换热、减少阻力、节省耗材的目的。
(7)设计了新型的局部波纹翅片形状,并进行了数值模拟验证。
传统的换热器强化换热措施,在强化换热的同时,往往都会引起阻力的大幅增加,而且通常都是阻力增加的百分比大于换热强化的百分比。
本文基于局部换热系数的模拟结果及节能减阻型换热器的设计原理,设计了波纹翅片位于上游,平直翅片位于下游的新型翅片形式,并且将该新型翅片的换热及阻力特性同现有的波纹翅片和平直翅片进行了对比研究。
对比结果表明,相对于原来的波纹翅片,新型翅片的换热性能仅仅减小4%,而阻力损失却减小了18%;相对于平直翅片,新型翅片的换热性能增加了45%,而阻力损失仅增加了26%,换热的强化大于阻力的增加,证明了新型翅片结构具有很好的强化换热及节能减阻性能。
(8)提出了椭圆管波纹翅片的换热器结构形式,数值研究了椭圆管波纹翅片换热器的流动与换热特性。
结果表明,椭圆管布置相对于圆管布置,可以在压降仅增加10%的条件下,使换热性能强化30%,因此椭圆管代替圆管,可以达到较好的强化换热和节能减阻的综合效果。
随着椭圆管向心率、翅片间距、横向管间距的增加以及翅片厚度的减小,椭圆管波纹翅片换热器的换热系数减小,同时阻力因子也减小。
(9)进一步分析了椭圆管的横截面形状对换热及阻力性能的影响。
将5种不同管截面形状的波纹翅片管换热器的换热和阻力性能进行了对比研究,结果表明,4种椭圆管的换热性能都比圆管好,分别平均强化了17.0%,16.9%,14.6%,12.3%;和圆管具有相同最窄空气流通截面的椭圆管的平均阻力损失比圆管高7.1%,其他3种椭圆管的阻力性能都比圆管好,分别减少了23.9%,20.7%,17.0%;从换热的角度,和圆管具有相同当量直径的椭圆管的强化换热效果最好;而从减阻的角度看,则是和圆管具有相同管周长的椭圆管的减阻效果最好,在实际应用时可以根据具体强化换热与节能减阻要求加以合理选择。
关键词:CO2制冷剂;跨临界循环;流动与换热;强化换热;场协同原理Experimental Study on CO2 Residential Air-condition System and Numerical Simulation on Enhanced Heat Transfer of Heat ExchangersTao YubingABSTRACTIn recent years, the problems of environment and energy have been more and more serious. Ozone depletion, greenhouse effect and energy crisis have become the main challenges for human being. The refrigerants used in refrigeration and air-condition systems not only make ozonosphere destroyed seriously but also cause great greenhouse effect. Looking for alternative refrigerant has become an exigent task for refrigeration industry. Due to the favorable thermophysical properties and benign environment effects, CO2 has attracted extensive attentions in recent years. On the other hand, the requirement for energy is more and more increasing and the combustion of fossil energy exhausts a large amount of greenhouse gas which aggravates the greenhouse effect. We are facing the threats of fossil energy drying up and environmental pollution. How to effectively utilize energy and efficiently protect ecological environment has become the key issue for all the countries. So it is very important to study the enhanced heat transfer and decreased pressure drop characteristics of the heat transfer equipments which are widely used in many fields.The objectives of present dissertation are focused on the alternative refrigerants of air-condition system and energy saving of heat transfer equipments. The corresponding experimental and theoretical studies are performed. In the experimental study, the domestic first test rig for the performance of CO2 residential air-condition system is set up. The effects of operating conditions on the heat transfer and fluid flow performances of heat exchangers and the system total performances are experimentally investigated. The throttling loss, effect of throttling loss on COP and influencing factors on throttling loss are analyzed for the CO2 transcritical cycle with an inner heat exchanger. Some reliable approaches to reduce throttling loss and improve the system performance are presented. In the theoretical analysis, a hybrid grid generation technology is proposed based on body fitted coordinates and block structured grid generation method, three-dimensional grid generation and numerical simulation codes are developed. Then the heat transfer and fluid flow characteristics of wavy fin-and-tube heat exchangers which are widely used in industry fields and air-condition systems are numerically studied. The effects of geometric parameters and operating conditions on the total heat transfer and fluid flow performance and fin efficiency of the heat exchanger are examined. Then the distributions of local heat transfer coefficient and fin efficiency on the plain plate fin and wavy fin surface are examined. Based on thedistribution results, a new type of high efficient heat exchanger is designed and the performance is investigated. The detailed contents and findings of the present dissertation are as follows.Experimental study on CO2 residential air-condition system:(1) The domestic first test rig for the performance study of CO2residential air-condition system is set up. At present, CO2 as a natural refrigerant had been successfully used in automobile air-condition, heat bump hot water and commercial refrigeration systems. However, the applications of CO2 refrigerant in residential air-condition system are still in the experimental validation period. In order to promote the application of CO2 in residential air-condition, the experimental system is designed and the test rig is developed based on the theoretical analysis which fully considers the higher pressure in the gas cooler side (about 7.0-12.0MPa) and existing explosion and leakage problems. The design of the experimental system and the precision and reliability of the experimental results have been fully validated and affirmed by the Japanese cooperators. Then, the effects of operating conditions on heat transfer and fluid flow performance of evaporator and gas cooler and the total performance of the air-condition system are experimentally investigated. The experimental results show that COP of the CO2 residential air-condition system generally locates between 2 and 3, which is a bit lower than that of traditional air-condition system. The cooling effect of gas cooler is the main influencing factor for COP, so enhancing the cooling effect of the gas cooler is an effective approach to improve the system performance. The COP of the CO2 system can achieve the level of traditional air-condition system by cycle optimization and adopting proper enhanced heat transfer method to the gas cooler. The experimental results of present dissertation demonstrate that the natural refrigerant CO2 is applicable to the residential air-condition system.(2) Throttling loss of the transcritical cycle, effect of throttling loss on COP and the influencing factors on throttling loss are analyzed based on the CO2transcritical air-condition experimental system with an inner heat exchanger. The results show that the inner heat exchanger can decrease throttling loss in a large degree, but it can not eliminate throttling loss. To the cycle with an inner heat exchanger, there is still 5% cooling capacity loss in throttling process, which decreases COP about 20%. The further studies on the influencing factors to throttling loss are performed and it is found that the cooling effect of gas cooler is the major influencing factor for throttling loss. The throttling loss decreases and the COP increases with the improvement of the cooling effect.Numerical study on enhanced heat transfer and decreased pressure drop characteristics of wavy fin-and-tube heat exchangers:(3) A hybrid grid generation method based on body fitted coordinates and block structured grid generation method is proposed. At present, heat exchangers used in air-condition system are mostly wavy fin-and-tube pattern. There are wavy channels and tubes between two fins. Due to the complicated geometric configuration, the grid generation is very difficult, so three-dimensional numerical simulations on wavy fin-and-tube surface have not been opened out until recent years. In present dissertation, a hybrid grid generation method is proposed, and then three-dimensional gridgeneration code and numerical simulation code based on SIMPLE algorithm are developed in body fitted coordinates. The codes can be used to simulate the heat transfer and fluid flow problems in complicated three-dimensional regions and derive the total heat transfer and fluid flow performances of the computational region and the distributions of local heat transfer coefficient, temperature field and fluid field. And then, the configurations and dimensions of the heat transfer surface can be optimized and validated and the enhanced heat transfer and decreased pressure drop characteristics of the heat transfer equipments can be achieved in virtue of the simulation code. And the simulation code can efficiently deal with the fluid-solid conjugated problem.(4) Based on the self-developed grid generation and numerical simulation codes, the three-dimensional numerical studies on the air-side laminar flow and heat transfer performances of the wavy fin-and-tube heat exchangers are performed. The effects of Reynolds number, fin pitch, wavy angle and tube row number on heat transfer and fluid flow characteristics of wavy fin-and-tube heat exchangers are investigated. And the effect mechanism of the parameters on heat transfer performance are discussed and well explained from the point of view of field synergy principle. The numerical results show that with the increases of Reynolds number, wavy angle and the decrease of fin pitch, tube row number, heat transfer performance of the heat exchanger is enhanced, but at the same time the pressure drop is increased. Then, correlation between the unit volume heat transfer capacity and the whole field average synergy angle is set up. The effects of the parameters on heat transfer characteristics of wavy fin heat exchanger with circular or elliptic tubes can be properly revealed by the correlation. The correlation can make the field synergy principle used in the design optimization of heat exchanger configuration more conveniently.(5) Effects of Reynolds number, wavy angle, fin pitch, fin thickness and transverse tube pitch on fin efficiency of wavy fin surface are analyzed numerically. The results show that with the increases of Reynolds number, wavy angle, fin pitch, transverse tube pitch and the decrease of the fin thickness, average temperature on fin surface decreases which leads to the decrease of fin efficiency. In a lot of the published papers, the isothermal model is adopted which neglects the fin efficiency and fin thickness and the fin is simplified as an isothermal surface without thickness. The present paper show that when the thermal conductivity of the fin material is relatively high and the velocity of the air is relatively small, the effects of geometric parameters on fin efficiency is very weak. And the isothermal model without thinking about the fin efficiency is applicable if the precision requirement is not high. But the fin thickness has obvious effects on the heat transfer and fluid flow performance. So if the ratio of the fin thickness and fin pitch is not very small, the fin thickness must be taken into account even to the isothermal model.(6) Local heat transfer coefficient and fin efficiency distributions on wavy fin and plate fin surfaces are investigated numerically and the design principle for the high efficient heat exchanger is derived. Due to the complicated configuration of the wavy fin-and-tube heat exchanger, the studies on the distributions of local heat transfer coefficient and fin efficiency on the wavy finsurface have not been reported in the published papers. However, these local distribution characteristics of the parameters are indispensable for the design of high efficient heat exchangers. So, it is very important to perform those studies. In present dissertation, the distribution characteristics of the local heat transfer coefficient and fin efficiency on wavy fin surface are derived by numerical method. The results show that local heat transfer coefficient generally decreases along air flow direction. At the locations of wave crest, the flow and heat transfer boundary is broken by the wave crest and the local heat transfer coefficient presents an obviously increasing tendency. At the locations of wave trough, there exist circumfluence and the vortexes are formed, so the local heat transfer coefficient presents a sharply decreasing tendency. The larger the air velocity and wavy angle, the more obvious the fluctuation. Local fin efficiency increases along air flow direction, its distribution characteristics basically depends on the distribution of temperature. Then the design principle for the high efficient heat exchanger is derived that convective heat transfer mostly occurs at the inlet region for the fin-and-tube heat exchangers when the air velocity is lower, so the corrugations at outlet region have little effects on heat transfer but greatly increase pressure drop. If we properly augment the heat transfer area and wavy angle at the inlet region and reduce them at the outlet region, the goals of enhanced heat transfer, decreased pressure drop and saving material can be realized.(7) A new type of local wavy fin is designed and its performances are validated. The traditional enhanced heat transfer approaches for heat exchanger always cause the great increase of pressure drop. And the increase percentage for the pressure drop is usually higher than the enhanced percentage of heat transfer performance. In this dissertation, on the basis of the above design principle, a new type of wavy fin pattern is designed which has wavy fin in the upstream and plain plate fin in the downstream. Then the comparison studies on the heat transfer and fluid flow performances of the new type fin pattern and the traditional plate fin and wavy fin patterns are performed. The simulation results show that the heat transfer coefficient for the new fin pattern only decreases 4%, but friction factor decreases 18% compared with traditional wavy fin; the heat transfer coefficient increases about 45% and friction factor only increase 26% compared with plain plate fin. The enhancement of heat transfer is larger than the increase of pressure drop. So the new fin pattern has better enhanced heat transfer and decreased pressure drop characteristics.(8) Wavy fin heat exchanger with elliptic tubes is proposed and numerical studies on the heat transfer and fluid flow performance are performed. The results show that the elliptic tube arrangement can enhance heat transfer up to 30% and only increase friction factor about 10% compared with circular tube. So the goal of enhanced heat transfer and decreased pressure drop can be achieved by replacing the circular tube with elliptic tube. And with the increases of ellipse centrality, fin pitch, transverse tube pitch and the decrease of fin thickness, both the heat transfer coefficient and the friction factor of the elliptic tube heat exchanger decrease.(9) Effects of elliptic tube cross-section pattern on heat transfer and fluid flow characteristicsof wavy fin-and-tube heat exchangers are investigated. Contrastive study on the performances of five tube cross-section patterns are performed. The results show that heat transfer performances of all the four elliptic tube patterns are better than that of circular tube; the enhanced percentages are 17.0%, 16.9%, 14.6% and 12.3% respectively. The friction factor of the elliptic tube with the same minimum airside free-flow area as circular tube is about 7.1% larger than that of circular tube. However, the friction factors of the other three elliptic tubes are smaller than that of circular tube, the friction factors are decreased about 23.9%, 20.7% and 17.0% respectively. From the point of view of enhanced heat transfer, the elliptic tube with the same hydraulic diameter as circular tube has the best heat transfer performance and from the point of view of decreased pressure drop, the elliptic tube with the same perimeter as the circular tube has the smallest pressure drop. In practical applications, we can choose different tube cross-section patterns according to different enhanced heat transfer and decreased pressure drop needs.Key words: CO2refrigerant; Transcritical cycle; Fluid flow and heat transfer;Enhanced heat transfer; Field synergy principle。