{"title":"暴露于均匀壁温边界条件下的水平管中混合对流发展流的局部传热特性","authors":"Mark J. Coetzee , Deniel Steyn , Marilize Everts","doi":"10.1016/j.ijthermalsci.2024.109167","DOIUrl":null,"url":null,"abstract":"<div><p>Extensive research has been conducted on the heat transfer characteristics related to the boundary conditions present in phase-change applications. However, there remains a fundamental gap in understanding the local heat transfer characteristics of mixed convective laminar flow exposed to a uniform wall temperature boundary condition. Furthermore, there is a disparity between numerical and experimental studies investigating this boundary condition. This study addresses these gaps by being the first to experimentally investigate the local heat transfer characteristics of developing laminar flow through a horizontal tube exposed to a uniform wall temperature boundary condition. A novel experimental setup was developed to measure the mean fluid temperatures along a 5 m-long copper tube with an inner diameter of 4.9 mm. While the local results indicated an increase in wall temperature along the test section, the average Nusselt numbers correlated well with literature, indicating that similar temperature trends existed in prior experimental studies. The local heat transfer characteristics for developing laminar uniform wall temperature flow were divided into four regions: (1) Free Convection Developing, (2) Free Convection Governing, (3) Sustained Free Convection, and (4) Diminishing Heat Transfer. Free convection effects were found to increase near the inlet of the tube and the associated secondary flow assisted the flow in becoming fully developed. However, due to the decreasing wall-fluid temperature differences, free convection effects could not be sustained, and heat transfer eventually diminished as the fluid temperatures approached the wall temperatures.</p></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":null,"pages":null},"PeriodicalIF":4.9000,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1290072924002898/pdfft?md5=6a66ac656621ff872705e76054bd0d41&pid=1-s2.0-S1290072924002898-main.pdf","citationCount":"0","resultStr":"{\"title\":\"The local heat transfer characteristics associated with mixed convective developing flow through a horizontal tube exposed to a uniform wall temperature boundary condition\",\"authors\":\"Mark J. Coetzee , Deniel Steyn , Marilize Everts\",\"doi\":\"10.1016/j.ijthermalsci.2024.109167\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Extensive research has been conducted on the heat transfer characteristics related to the boundary conditions present in phase-change applications. However, there remains a fundamental gap in understanding the local heat transfer characteristics of mixed convective laminar flow exposed to a uniform wall temperature boundary condition. Furthermore, there is a disparity between numerical and experimental studies investigating this boundary condition. This study addresses these gaps by being the first to experimentally investigate the local heat transfer characteristics of developing laminar flow through a horizontal tube exposed to a uniform wall temperature boundary condition. A novel experimental setup was developed to measure the mean fluid temperatures along a 5 m-long copper tube with an inner diameter of 4.9 mm. While the local results indicated an increase in wall temperature along the test section, the average Nusselt numbers correlated well with literature, indicating that similar temperature trends existed in prior experimental studies. The local heat transfer characteristics for developing laminar uniform wall temperature flow were divided into four regions: (1) Free Convection Developing, (2) Free Convection Governing, (3) Sustained Free Convection, and (4) Diminishing Heat Transfer. Free convection effects were found to increase near the inlet of the tube and the associated secondary flow assisted the flow in becoming fully developed. However, due to the decreasing wall-fluid temperature differences, free convection effects could not be sustained, and heat transfer eventually diminished as the fluid temperatures approached the wall temperatures.</p></div>\",\"PeriodicalId\":341,\"journal\":{\"name\":\"International Journal of Thermal Sciences\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":4.9000,\"publicationDate\":\"2024-05-24\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://www.sciencedirect.com/science/article/pii/S1290072924002898/pdfft?md5=6a66ac656621ff872705e76054bd0d41&pid=1-s2.0-S1290072924002898-main.pdf\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"International Journal of Thermal Sciences\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S1290072924002898\",\"RegionNum\":2,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"ENGINEERING, MECHANICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"International Journal of Thermal Sciences","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1290072924002898","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, MECHANICAL","Score":null,"Total":0}
The local heat transfer characteristics associated with mixed convective developing flow through a horizontal tube exposed to a uniform wall temperature boundary condition
Extensive research has been conducted on the heat transfer characteristics related to the boundary conditions present in phase-change applications. However, there remains a fundamental gap in understanding the local heat transfer characteristics of mixed convective laminar flow exposed to a uniform wall temperature boundary condition. Furthermore, there is a disparity between numerical and experimental studies investigating this boundary condition. This study addresses these gaps by being the first to experimentally investigate the local heat transfer characteristics of developing laminar flow through a horizontal tube exposed to a uniform wall temperature boundary condition. A novel experimental setup was developed to measure the mean fluid temperatures along a 5 m-long copper tube with an inner diameter of 4.9 mm. While the local results indicated an increase in wall temperature along the test section, the average Nusselt numbers correlated well with literature, indicating that similar temperature trends existed in prior experimental studies. The local heat transfer characteristics for developing laminar uniform wall temperature flow were divided into four regions: (1) Free Convection Developing, (2) Free Convection Governing, (3) Sustained Free Convection, and (4) Diminishing Heat Transfer. Free convection effects were found to increase near the inlet of the tube and the associated secondary flow assisted the flow in becoming fully developed. However, due to the decreasing wall-fluid temperature differences, free convection effects could not be sustained, and heat transfer eventually diminished as the fluid temperatures approached the wall temperatures.
期刊介绍:
The International Journal of Thermal Sciences is a journal devoted to the publication of fundamental studies on the physics of transfer processes in general, with an emphasis on thermal aspects and also applied research on various processes, energy systems and the environment. Articles are published in English and French, and are subject to peer review.
The fundamental subjects considered within the scope of the journal are:
* Heat and relevant mass transfer at all scales (nano, micro and macro) and in all types of material (heterogeneous, composites, biological,...) and fluid flow
* Forced, natural or mixed convection in reactive or non-reactive media
* Single or multi–phase fluid flow with or without phase change
* Near–and far–field radiative heat transfer
* Combined modes of heat transfer in complex systems (for example, plasmas, biological, geological,...)
* Multiscale modelling
The applied research topics include:
* Heat exchangers, heat pipes, cooling processes
* Transport phenomena taking place in industrial processes (chemical, food and agricultural, metallurgical, space and aeronautical, automobile industries)
* Nano–and micro–technology for energy, space, biosystems and devices
* Heat transport analysis in advanced systems
* Impact of energy–related processes on environment, and emerging energy systems
The study of thermophysical properties of materials and fluids, thermal measurement techniques, inverse methods, and the developments of experimental methods are within the scope of the International Journal of Thermal Sciences which also covers the modelling, and numerical methods applied to thermal transfer.