Omar Rafae Alomar, Omar Mohammed Ali, Shaswar Omar Osman Al-Omar
{"title":"Free convective heat transfer induced inside a vented duct having two aligned hot and cold cylinders: An experimental study","authors":"Omar Rafae Alomar, Omar Mohammed Ali, Shaswar Omar Osman Al-Omar","doi":"10.1002/htj.23067","DOIUrl":null,"url":null,"abstract":"<p>Free convective heat transfer created from two aligned cylinders immersed inside a vented air duct is experimentally investigated. The experiments include the measurements of cylinders temperature and the air temperature inside the enclosure under steady, turbulent, and incompressible flow properties by using steady-state heat equations. The studied parameters include Rayleigh number (<span></span><math>\n <semantics>\n <mrow>\n <msup>\n <mn>10</mn>\n \n <mn>5</mn>\n </msup>\n \n <mo>≤</mo>\n \n <mi>Ra</mi>\n \n <mo>≤</mo>\n \n <msup>\n <mrow>\n <mn>3.4</mn>\n \n <mo>×</mo>\n \n <mn>10</mn>\n </mrow>\n \n <mn>6</mn>\n </msup>\n </mrow>\n <annotation> ${10}^{5}\\le {Ra}\\le {3.4\\times 10}^{6}$</annotation>\n </semantics></math>), opening sizes at lower and upper enclosure surfaces (<span></span><math>\n <semantics>\n <mrow>\n <mn>0.146</mn>\n \n <mo>≤</mo>\n \n <mi>O</mi>\n \n <mo>≤</mo>\n \n <mn>1</mn>\n </mrow>\n <annotation> $0.146\\le O\\le 1$</annotation>\n </semantics></math>), and space size between cylinders (<span></span><math>\n <semantics>\n <mrow>\n <mn>0.35</mn>\n \n <mo>≤</mo>\n \n <mi>S</mi>\n \n <mo>≤</mo>\n \n <mn>0.532</mn>\n </mrow>\n <annotation> $0.35\\le S\\le 0.532$</annotation>\n </semantics></math>) with the constant ratio of enclosure width to cylinder diameter equal to 6. The findings displayed that the average air temperature inside the enclosure for the low values of <i>S</i> and <i>O</i> is low, and it rises as <i>S</i> is raised. The behaviors of <i>Nu</i> differ with changing <i>Ra</i> values. An interaction between hot cylinder and cold cylinder inside the enclosure is observed that depends on <i>O</i> and <i>S</i> values, and hence, they have a large impact on fluid temperature. The data indicated that <span></span><math>\n <semantics>\n <mrow>\n <mi>Nu</mi>\n </mrow>\n <annotation> ${Nu}$</annotation>\n </semantics></math> rises with the <span></span><math>\n <semantics>\n <mrow>\n <mi>Ra</mi>\n </mrow>\n <annotation> ${Ra}$</annotation>\n </semantics></math> for all <span></span><math>\n <semantics>\n <mrow>\n <mi>S</mi>\n </mrow>\n <annotation> $S$</annotation>\n </semantics></math> and <span></span><math>\n <semantics>\n <mrow>\n <mi>O</mi>\n </mrow>\n <annotation> $O$</annotation>\n </semantics></math> values. The value of <span></span><math>\n <semantics>\n <mrow>\n <mi>Nu</mi>\n </mrow>\n <annotation> ${Nu}$</annotation>\n </semantics></math> for each cylinder depends on the values of <span></span><math>\n <semantics>\n <mrow>\n <mi>S</mi>\n </mrow>\n <annotation> $S$</annotation>\n </semantics></math> and <span></span><math>\n <semantics>\n <mrow>\n <mi>O</mi>\n </mrow>\n <annotation> $O$</annotation>\n </semantics></math>. The maximum <span></span><math>\n <semantics>\n <mrow>\n <mi>Nu</mi>\n </mrow>\n <annotation> ${Nu}$</annotation>\n </semantics></math> value has been obtained when <span></span><math>\n <semantics>\n <mrow>\n <mi>O</mi>\n \n <mo>=</mo>\n \n <mn>0.439</mn>\n </mrow>\n <annotation> $O=0.439$</annotation>\n </semantics></math> and <span></span><math>\n <semantics>\n <mrow>\n <mi>S</mi>\n \n <mo>=</mo>\n \n <mn>0.35</mn>\n </mrow>\n <annotation> $S=0.35$</annotation>\n </semantics></math> with maximum enhancement between 30% and 50% depending on <i>Ra</i> values as compared with <span></span><math>\n <semantics>\n <mrow>\n <mi>O</mi>\n \n <mo>=</mo>\n \n <mn>0.146</mn>\n </mrow>\n <annotation> $O=0.146$</annotation>\n </semantics></math> and <span></span><math>\n <semantics>\n <mrow>\n <mi>S</mi>\n \n <mo>=</mo>\n \n <mn>0.523</mn>\n </mrow>\n <annotation> $S=0.523$</annotation>\n </semantics></math>, whereas the minimum average <span></span><math>\n <semantics>\n <mrow>\n <mi>Nu</mi>\n </mrow>\n <annotation> ${Nu}$</annotation>\n </semantics></math> has been indicated when <span></span><math>\n <semantics>\n <mrow>\n <mi>O</mi>\n \n <mo>=</mo>\n \n <mn>0.146</mn>\n </mrow>\n <annotation> $O=0.146$</annotation>\n </semantics></math> and <span></span><math>\n <semantics>\n <mrow>\n <mi>S</mi>\n \n <mo>=</mo>\n \n <mn>0.35</mn>\n </mrow>\n <annotation> $S=0.35$</annotation>\n </semantics></math>. The profiles of <span></span><math>\n <semantics>\n <mrow>\n <mi>Nu</mi>\n </mrow>\n <annotation> ${Nu}$</annotation>\n </semantics></math> reveal that <span></span><math>\n <semantics>\n <mrow>\n <mi>O</mi>\n </mrow>\n <annotation> $O$</annotation>\n </semantics></math>, <span></span><math>\n <semantics>\n <mrow>\n <mi>Ra</mi>\n </mrow>\n <annotation> ${Ra}$</annotation>\n </semantics></math>, and <span></span><math>\n <semantics>\n <mrow>\n <mi>S</mi>\n </mrow>\n <annotation> $S$</annotation>\n </semantics></math> have a considerable influence on heat transfer.</p>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":null,"pages":null},"PeriodicalIF":2.8000,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Heat Transfer","FirstCategoryId":"1085","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/htj.23067","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"THERMODYNAMICS","Score":null,"Total":0}
引用次数: 0
Abstract
Free convective heat transfer created from two aligned cylinders immersed inside a vented air duct is experimentally investigated. The experiments include the measurements of cylinders temperature and the air temperature inside the enclosure under steady, turbulent, and incompressible flow properties by using steady-state heat equations. The studied parameters include Rayleigh number (), opening sizes at lower and upper enclosure surfaces (), and space size between cylinders () with the constant ratio of enclosure width to cylinder diameter equal to 6. The findings displayed that the average air temperature inside the enclosure for the low values of S and O is low, and it rises as S is raised. The behaviors of Nu differ with changing Ra values. An interaction between hot cylinder and cold cylinder inside the enclosure is observed that depends on O and S values, and hence, they have a large impact on fluid temperature. The data indicated that rises with the for all and values. The value of for each cylinder depends on the values of and . The maximum value has been obtained when and with maximum enhancement between 30% and 50% depending on Ra values as compared with and , whereas the minimum average has been indicated when and . The profiles of reveal that , , and have a considerable influence on heat transfer.
实验研究了浸入通风管道内的两个排列整齐的圆柱体产生的自由对流传热。实验包括在稳定、湍流和不可压缩流动特性下,利用稳态热方程测量圆柱体温度和围护结构内的空气温度。所研究的参数包括瑞利数()、下表面和上表面的开口尺寸()以及圆柱体之间的空间尺寸(),其中外壳宽度与圆柱体直径之比恒定为 6。研究结果表明,在 S 和 O 值较低时,外壳内的平均气温较低,随着 S 值的升高,平均气温逐渐升高。随着 Ra 值的变化,Nu 的表现也不同。观察到外壳内热气缸和冷气缸之间的相互作用取决于 O 值和 S 值,因此它们对流体温度有很大影响。数据表明,所有和的值都会升高。每个气缸的值取决于 和 的值。与 、 和 相比,当 、 和 时获得最大值,根据 Ra 值的不同,最大值提高 30% 至 50%,而当 和 时,平均值最小。和 的曲线显示, 和 对热传递有相当大的影响。