- 1、本文档共22页,可阅读全部内容。
- 2、有哪些信誉好的足球投注网站(book118)网站文档一经付费(服务费),不意味着购买了该文档的版权,仅供个人/单位学习、研究之用,不得用于商业用途,未经授权,严禁复制、发行、汇编、翻译或者网络传播等,侵权必究。
- 3、本站所有内容均由合作方或网友上传,本站不对文档的完整性、权威性及其观点立场正确性做任何保证或承诺!文档内容仅供研究参考,付费前请自行鉴别。如您付费,意味着您自己接受本站规则且自行承担风险,本站不退款、不进行额外附加服务;查看《如何避免下载的几个坑》。如果您已付费下载过本站文档,您可以点击 这里二次下载。
- 4、如文档侵犯商业秘密、侵犯著作权、侵犯人身权等,请点击“版权申诉”(推荐),也可以打举报电话:400-050-0827(电话支持时间:9:00-18:30)。
- 5、该文档为VIP文档,如果想要下载,成为VIP会员后,下载免费。
- 6、成为VIP后,下载本文档将扣除1次下载权益。下载后,不支持退款、换文档。如有疑问请联系我们。
- 7、成为VIP后,您将拥有八大权益,权益包括:VIP文档下载权益、阅读免打扰、文档格式转换、高级专利检索、专属身份标志、高级客服、多端互通、版权登记。
- 8、VIP文档为合作方或网友上传,每下载1次, 网站将根据用户上传文档的质量评分、类型等,对文档贡献者给予高额补贴、流量扶持。如果你也想贡献VIP文档。上传文档
查看更多
* * * * * * * * * * * * * Lesson 22 Heat Transfer How is the heat transfer? Mechanism of Convection Applications . Mean fluid Velocity and Boundary and their effect on the rate of heat transfer. Fundamental equation of heat transfer Logarithmic-mean temperature difference. Heat transfer Coefficients. Heat flux and Nusselt correlation Simulation program for Heat Exchanger How is the heat transfer? Heat can transfer between the surface of a solid conductor and the surrounding medium whenever temperature gradient exists. Conduction Convection Natural convection Forced Convection Natural and forced Convection Natural convection occurs whenever heat flows between a solid and fluid, or between fluid layers. As a result of heat exchange Change in density of effective fluid layers taken place, which causes upward flow of heated fluid. If this motion is associated with heat transfer mechanism only, then it is called Natural Convection Forced Convection If this motion is associated by mechanical means such as pumps, gravity or fans, the movement of the fluid is enforced. And in this case, we then speak of Forced convection. Heat Exchangers A device whose primary purpose is the transfer of energy between two fluids is named a Heat Exchanger. Applications of Heat Exchangers Heat Exchangers prevent car engine overheating and increase efficiency Heat exchangers are used in Industry for heat transfer Heat exchangers are used in AC and furnaces The closed-type exchanger is the most popular one. One example of this type is the Double pipe exchanger. In this type, the hot and cold fluid streams do not come into direct contact with each other. They are separated by a tube wall or flat plate. Principle of Heat Exchanger First Law of Thermodynamic: “Energy is conserved.” 0 0 0 0 Control Volume Qh Cross Section Area HOT COLD Thermal Boundary Layer Q hot Q cold Th Ti,wall To,wall Tc Region I : Hot Liquid-Solid Convection NEWTON’S LAW OF CCOLING Region II
您可能关注的文档
- 建筑力学 教学课件 ppt 作者 刘玉清 张成 主编第十三章 静定结构的内力分析.PPT
- 建筑力学 教学课件 ppt 作者 刘玉清 张成 主编第十章 压杆稳定.ppt
- 建筑力学 教学课件 ppt 作者 刘玉清 张成 主编第四章 平面一般力系.ppt
- 建筑力学 教学课件 ppt 作者 刘玉清 张成 主编第五章 材料力学基础.ppt
- 建筑力学与结构 教学课件 ppt 作者0绪论.ppt
- 建筑力学与结构 教学课件 ppt 作者第1章 静力学的基本概念.ppt
- 建筑力学与结构 教学课件 ppt 作者第2章 平面力系.ppt
- 建筑力学与结构 教学课件 ppt 作者第3章 静定结构.ppt
- 建筑力学与结构 教学课件 ppt 作者第4章 平面静定桁架.ppt
- 建筑力学与结构 教学课件 ppt 作者第5章 轴向拉伸和压缩.ppt
文档评论(0)