Heat Transfer: Volume 2最新文献_第9页

Dynamics of Intermittent Sprays 间歇喷雾动力学

Heat Transfer: Volume 2 Pub Date : 1999-11-14 DOI: 10.1115/imece1999-1047

B. Jawad

引用次数: 0

Local Furnace Data and Modeling Comparison for a 600MWe Coal-Fired Utility Boiler 600MWe燃煤电站锅炉局部炉膛数据及建模比较

Heat Transfer: Volume 2 Pub Date : 1999-11-14 DOI: 10.1115/imece1999-1050

Y. Hwang, J. Howell

引用次数: 0

An Unstructured-Mesh Methodology for Computation of Reacting Sprays in Industrial Combustors 工业燃烧室反应喷雾计算的非结构网格方法

Heat Transfer: Volume 2 Pub Date : 1999-11-14 DOI: 10.1115/imece1999-1055

M. Giridharan, J. Sheu, S. Bayyuk, C. Presser

{"title":"An Unstructured-Mesh Methodology for Computation of Reacting Sprays in Industrial Combustors","authors":"M. Giridharan, J. Sheu, S. Bayyuk, C. Presser","doi":"10.1115/imece1999-1055","DOIUrl":"https://doi.org/10.1115/imece1999-1055","url":null,"abstract":"\u0000 This paper reports the progress made in developing a state-of-the-art, unstructured-mesh code for simulating reacting two-phase flows for general-purpose industrial applications. The code has been created by combining a finite-volume solver for computing flow, heat-transfer, and chemical reaction in the gas phase with a new object-oriented module specifically designed and developed to provide a framework for solving the system of equations governing the motion of spray droplets and their interactions with the gas phase. The gas phase equations are solved in an Eulerian frame while the droplet equations are solved in a Lagrangian frame. The paper presents the equations for droplet transport and behavior, describes the coupling models between the gas and liquid phases, and outlines the overall solution technique. Much of the paper is devoted to verification and validation of the computational models. The verification studies include comparison of computational results for particle motion under the influence of gravity and for solutions. The validation studies include comparison of predictions with published experimental data on behavior of evaporating and non-evaporating sprays. All comparisons show good qualitative and quantitative agreement. A 2-D axisymmetric simulation of methanol combustion in the N1ST reference spray combustor is also presented, and the results are compared with the NIST flow visualization data. Relevant ongoing work and future plans for incorporation of advanced spray models are briefly described.","PeriodicalId":201774,"journal":{"name":"Heat Transfer: Volume 2","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126184579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Numerical Simulation of Blend Combustion of Coal and Feedlot Waste in a Swirl Burner 旋流燃烧器中煤与饲草混合燃烧的数值模拟

Heat Transfer: Volume 2 Pub Date : 1999-11-14 DOI: 10.1115/imece1999-1048

M. Sami, K. Annamalai, S. Dhanapalan, M. Wooldridge

引用次数: 8

Melting Rate of a Solid With Periodic Melt Removal 具有周期性熔体去除的固体的熔化速率

Heat Transfer: Volume 2 Pub Date : 1999-11-14 DOI: 10.1115/imece1999-1035

V. Nemchinsky

{"title":"Melting Rate of a Solid With Periodic Melt Removal","authors":"V. Nemchinsky","doi":"10.1115/imece1999-1035","DOIUrl":"https://doi.org/10.1115/imece1999-1035","url":null,"abstract":"\u0000 The melting rate of a solid, subjected to a heat flux at its surface, changes with time. When a fresh unmelted surface is first exposed to a heat source, the melting isotherm moves quickly inside the solid. Then its motion slows down: this decrease in melting rate is obviously because of increasing thermal resistance of the growing liquid layer that separates solid-liquid interface from the heat source. If the liquid layer is not removed, the melting rate approaches zero. The resultant melting rate depends on the manner in which the melt is removed. In a number of cases of practical interest, the melt is removed not continuously but periodically, in the form of drops. For example, during arc welding with a consumable electrode, these drops are accumulated at the tip of the electrode. When the drop becomes big enough, it is detached from the electrode under action of gravity or electromagnetic force the melt is removed not continuously but periodically, in the form of drops. A simple approximate method is suggested to calculate the melting rate of a solid in the case when melt is removed periodically in form of drops. The method allows one to consider separately the heat transfer in the solid and in the liquid and, thus, to include different heat processes in both phases. Good agreement was demonstrated for exact and approximate solutions for a wide range of parameters.","PeriodicalId":201774,"journal":{"name":"Heat Transfer: Volume 2","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122115884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A Theoretical Treatment of Critical Heat Flux on Metal-Graphite Composite Heating Surfaces 金属-石墨复合受热面临界热流的理论处理

Heat Transfer: Volume 2 Pub Date : 1999-11-14 DOI: 10.1115/imece1999-1042

Wen‐Jei Yang, Nengli Zhang

{"title":"A Theoretical Treatment of Critical Heat Flux on Metal-Graphite Composite Heating Surfaces","authors":"Wen‐Jei Yang, Nengli Zhang","doi":"10.1115/imece1999-1042","DOIUrl":"https://doi.org/10.1115/imece1999-1042","url":null,"abstract":"\u0000 This paper presents a theoretical treatment of the critical heat flux on metal-graphite composite surfaces. A previous study found that the tips of graphite-fibers act as bubble nucleation sites. Throughout the transition boiling regime, vapor rises into liquid on the nodes of the Taylor waves in reference to the Rayleigh-Taylor instability theory. At the critical (i.e., maximum) heat flux, this rising vapor forms into jets. These jets come from the graphite fiber tips that are arranged in an equilateral triangular grid in the metal matrix. The basic spacing of the grid is the two-dimensional Taylor wavelength, which is the spacing of the most basic module of jets. At the peak heat flux, the Kelvin-Helmholtz instability causes the jets to become unstable and brings about burnout. In other words, this instability theory predicts when the vapor velocity in the jet will reach a critical value to cause the vapor jets to cave in. The existing empirical results indicate that the nucleate pool boiling curves for metal-graphite composites of different graphite concentrations (i.e., area fractions) congregate near the critical heat flux of the composite for the optimum performance as the degree of superheat increases. With this particular graphite-fiber concentration known, a balance of the heat flux by the latent heat carried away in the jets when the liquid is saturated yields the maximum (i.e., critical) heat flux equation. Both copper-graphite and aluminum graphite composites are treated.","PeriodicalId":201774,"journal":{"name":"Heat Transfer: Volume 2","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124202100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Forced-Convective Condensation of Pure Steam and Ammonia-Steam Vapor Mixtures in a Shell-Tube Condenser 纯蒸汽和氨蒸汽混合物在壳管式冷凝器中的强制对流冷凝

Heat Transfer: Volume 2 Pub Date : 1999-11-14 DOI: 10.1115/imece1999-1009

R. K. Sharma, V. Hassani, R. Mahajan

{"title":"Forced-Convective Condensation of Pure Steam and Ammonia-Steam Vapor Mixtures in a Shell-Tube Condenser","authors":"R. K. Sharma, V. Hassani, R. Mahajan","doi":"10.1115/imece1999-1009","DOIUrl":"https://doi.org/10.1115/imece1999-1009","url":null,"abstract":"\u0000 In this paper, we present our experimental findings for the forced-convective condensation of pure steam and ammonia-steam vapor mixture in a horizontal annulus in a counter-current shell-tube condenser. Experiments with ammonia-steam mixtures were conducted for ∼ 90% ammonia concentration (by wt.) for vapor inlet mass fluxes ranging from 2 to 5 kg/m2s. The local heat transfer coefficient varied considerably along the condenser and this variation was strongly linked to the condensate flow patterns in the annulus. Based on a condensate drainage model, the flow in the annulus was mapped on to flow maps for horizontal in-tube condensing flows. The delineated flow regimes were utilized to explain augmentation or deterioration of local heat transfer in the condenser. The average heat transfer coefficients are presented as a function of the condensate and vapor Reynolds number for both steam and ammonia-steam mixture. The results for pure steam are higher than those predicted by annular flow correlation developed in the past. For ammonia-steam mixtures, the average heat transfer coefficients are about 16% of those for pure steam due to the vapor layer resistance at the interface.","PeriodicalId":201774,"journal":{"name":"Heat Transfer: Volume 2","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132240265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Water Flow Distribution in Horizontal Protruding-Type Header Contaminated With Bubbles 含气泡水平突出式集管内水流分布

Heat Transfer: Volume 2 Pub Date : 1999-11-14 DOI: 10.1115/imece1999-1015

S. Horiki, M. Osakabe

{"title":"Water Flow Distribution in Horizontal Protruding-Type Header Contaminated With Bubbles","authors":"S. Horiki, M. Osakabe","doi":"10.1115/imece1999-1015","DOIUrl":"https://doi.org/10.1115/imece1999-1015","url":null,"abstract":"\u0000 Flow header for small multiple pipes is commonly used in boilers and heat exchangers. The system contributes to raise the heat transfer efficiency in the components. The flow distribution mechanism of the header for water has been studied and the calculation procedure for the design has been recommended for a single-phase condition. It is also recommended to avoid the bubbles in the header to obtain a uniform water flow rate to each small pipe. But in some cases, the header has to be used to distribute a flow containing bubbles. Distribution behavior of water with a gas-phase was studied experimentally in a horizontal header with four vertical pipes. In the present experimental header, it was possible to protrude the branch pipes inside of the header and the effect of protruding length on the water distribution behavior was studied.\u0000 When the protruding length was 0, the water distribution rate to the first pipe rapidly increased and the rates to the others decreased with a small amount of bubbles. As the bubbles in the header were absorbed only into the first pipe, the average two-phase density in the first pipe decreased. The decreased pressure head promotes the rush of water into the first pipe such as in an airlift pump. By increasing the air flow rate in the header inlet further, the flow rate to the first pipe took a maximum and then tended to decrease. The increased air flow rate in the first pipe increased the pressure loss in the pipe and resulted in a reduction in the water flow rate. The more important and serious behavior could be seen in the other pipes where the water flow rate decreased to 1/5 of the uniform distribution rate. By increasing the protruding length, the non-uniform distribution of water was suppressed because the gas-phase entered not only the first pipe but also the others. The best result was obtained when the four branch pipes were protruded into the center of header.","PeriodicalId":201774,"journal":{"name":"Heat Transfer: Volume 2","volume":"191 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134358043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Effective Thermal Conductivity of the Mushy Region During Solidification of Aqueous Solutions of Ammonium Chloride 氯化铵水溶液凝固过程中糊状区的有效导热系数

Heat Transfer: Volume 2 Pub Date : 1999-11-14 DOI: 10.1115/imece1999-1036

M. Bianchi, R. Viskanta

引用次数: 1

Models for Annular Film Condensation in Vertical Tubes With Vapour Downflow: A Critical Review 垂直管内蒸汽下流环膜冷凝模型综述

Heat Transfer: Volume 2 Pub Date : 1999-11-14 DOI: 10.1115/imece1999-1008

A. Briggs

引用次数: 0