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Dimensionless Parameters for the Optimization of Annular-Finned Tubes 环形翅片管无量纲参数优化
Advances in Enhanced Heat Transfer Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1280
C. Cortés, I. Arauzo, A. Campo
{"title":"Dimensionless Parameters for the Optimization of Annular-Finned Tubes","authors":"C. Cortés, I. Arauzo, A. Campo","doi":"10.1115/imece2000-1280","DOIUrl":"https://doi.org/10.1115/imece2000-1280","url":null,"abstract":"\u0000 This paper addresses the problem of optimizing an array of annular fins starting from an empirical fit of the average convection coefficient that recognizes the influence of the fin spacing. A dimensionless formulation is proposed to reduce the number of independent parameters to only four, being applicable to a rather generic situation. The formulation is illustrated with a parametric study encompassing the ranges of interest of the variables: Reynolds number, thermal conductivity ratio, volume constraint and fin spacing and thickness. Applied to the standard designs of annular-finned heat exchangers, the method predicts fully coherent points of optimum thermal performance. A sequence is suggested to integrate the optimization process within the design calculations of heat exchangers, and several graphs are presented which are suitable to this purpose. The method can be applied to the design and scaling calculations of annular-finned tube bundles for gas-liquid or gas-gas applications.","PeriodicalId":369285,"journal":{"name":"Advances in Enhanced Heat Transfer","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132055277","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
Heat Transfer Enhancement by Turbulent Impinging Jets 紊流冲击射流增强传热
Advances in Enhanced Heat Transfer Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1279
M. Kumagai, R. Amano, M. Jensen
{"title":"Heat Transfer Enhancement by Turbulent Impinging Jets","authors":"M. Kumagai, R. Amano, M. Jensen","doi":"10.1115/imece2000-1279","DOIUrl":"https://doi.org/10.1115/imece2000-1279","url":null,"abstract":"\u0000 A numerical and experimental investigation on cooling of a solid surface was performed by studying the behavior of an impinging jet onto a fixed flat target. The local heat transfer coefficient distributions on a plate with a constant heat flux were computationally investigated with a normally impinging axisymmetric jet for nozzle diameter of 4.6mm at H/d = 4 and 10, with the Reynolds numbers of 10,000 and 40,000. The two-dimensional cylindrical Navier-Stokes equations were solved using a two-equation k-ε turbulence model. The finite-volume differencing scheme was used to solve the thermal and flow fields. The predicted heat transfer coefficients were compared with experimental measurements. A universal function based on the wave equation was developed and applied to the heat transfer model to improve calculated local heat transfer coefficients for short nozzle-to-plate distance (H/d = 4). The differences between H/d = 4 and 10 due to the correlation among heat transfer coefficient, kinetic energy and pressure were investigated for the impingement region. Predictions by the present model show good agreement with the experimental data.","PeriodicalId":369285,"journal":{"name":"Advances in Enhanced Heat Transfer","volume":"911 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123273520","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
Flow Boiling Heat Transfer With Binary and Ternary Mixtures in Microfin Tubes 二元和三元混合物在微翅片管内的流动沸腾传热
Advances in Enhanced Heat Transfer Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1275
Nirihiro Inoue, A. Goto, S. Kandlikar
{"title":"Flow Boiling Heat Transfer With Binary and Ternary Mixtures in Microfin Tubes","authors":"Nirihiro Inoue, A. Goto, S. Kandlikar","doi":"10.1115/imece2000-1275","DOIUrl":"https://doi.org/10.1115/imece2000-1275","url":null,"abstract":"\u0000 An experimental setup was designed and fabricated to test the flow boiling heat transfer performance of microfin tubes. Five microfin tubes were tested with pure refrigerants. Two tubes were selected for further testing with binary and ternary refrigerant mixtures. This paper reports the data for these two microfin tubes employing R22, R410A (mixture of 50% by weight of R32 and 50% of R125) and R407C (ternary mixture of 23 wt. % R32, 25 wt. % R125, and 52 wt. % R134a). A correlation scheme is presented for the heat transfer coefficient of mixtures in microfin tubes. In general, it is observed that the heat transfer performance of binary mixture R410A in microfin tubes is similar to pure R22; however, the performance of the ternary mixture R407C is lower than that with pure R22.","PeriodicalId":369285,"journal":{"name":"Advances in Enhanced Heat Transfer","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115106957","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
A Computational Study of Enhanced Heat Transfer in Laminar Flows of Non-Newtonian Fluids in Corrugated-Plate Channels 波纹板通道中非牛顿流体层流强化换热的计算研究
Advances in Enhanced Heat Transfer Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1277
H. Metwally, R. M. Manglik
{"title":"A Computational Study of Enhanced Heat Transfer in Laminar Flows of Non-Newtonian Fluids in Corrugated-Plate Channels","authors":"H. Metwally, R. M. Manglik","doi":"10.1115/imece2000-1277","DOIUrl":"https://doi.org/10.1115/imece2000-1277","url":null,"abstract":"\u0000 The enhanced heat transfer behavior of laminar shear-thinning, power-law fluid flows in sinusoidal corrugated-plate channels is investigated. With duct plates at uniform wall temperature, periodically developed flows are considered for a wide range of channel corrugation aspect ratio (0 ≤ γ ≤ 1), flow rates (10 ≤ Reg ≤ 1500), and pseudo-plastic flow behavior indices (n = 0.5, 0.8, and 1.0). Typical velocity and temperature distributions, along with extended results for isothermal friction factor f and Collburn factor j are presented. The enhanced forced convection is found to be strongly influenced by γ, and the flow field displays two distinct regimes: undisturbed laminar or no swirl, and swirl flow regimes. In the no-swirl regime, behavior similar to that in fully developed straight duct flows with no cross-stream disturbance is obtained. The shear-thinning nature of the fluid, however, decreases f and enhances j. In the swirl regime, flow separation and reattachment in the corrugation troughs generates transverse vortices that grow with Reg and γ. The transition to this regime is also seen to depend on Reg, γ, and n, and in shear-thinning flows, it occurs at a lower Reg. The combined effects of corrugated plate geometry and non-Newtonian fluid rheology produce a heat transfer enhancement, as measured by the factor j/f, of over 3.3 times that in a flat-plate channel depending upon γ, n, and Reg.","PeriodicalId":369285,"journal":{"name":"Advances in Enhanced Heat Transfer","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129432085","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
Effect of Promoter Orientation on Enhancement of Heat Transfer From Vertical Fins 促进剂取向对垂直翅片强化传热的影响
Advances in Enhanced Heat Transfer Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1281
S. Onbaşıoǧlu, Huseyin Onbasioglu, N. Egrican
{"title":"Effect of Promoter Orientation on Enhancement of Heat Transfer From Vertical Fins","authors":"S. Onbaşıoǧlu, Huseyin Onbasioglu, N. Egrican","doi":"10.1115/imece2000-1281","DOIUrl":"https://doi.org/10.1115/imece2000-1281","url":null,"abstract":"\u0000 The promoters redirect the flow and enhance the heat transfer both in laminar and turbulent cases. In the present study, the special care has been intensified first on the parameters such as the height and the pitch of the promoters and then the orientation of the repeated promoters with varying heights has been investigated. It is concluded that the enhancement of the heat transfer is sensitive to all of the parameters. Meanwhile, turbulence has been observed exceeding a certain value of the promoter height and the separation region occurring along the downstream plate has been analyzed. The flow and temperature fields have been obtained by means of a modified k-epsilon turbulence model developed for the present case. Results of the 3-D computations compare well with the experimental observations.","PeriodicalId":369285,"journal":{"name":"Advances in Enhanced Heat Transfer","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116540773","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
Theoretical Modeling of Ice Formation Using Direct Contact Heat Exchange 采用直接接触热交换的冰形成理论模型
Advances in Enhanced Heat Transfer Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1286
D. Chau, P. Phelan, B. Wood
{"title":"Theoretical Modeling of Ice Formation Using Direct Contact Heat Exchange","authors":"D. Chau, P. Phelan, B. Wood","doi":"10.1115/imece2000-1286","DOIUrl":"https://doi.org/10.1115/imece2000-1286","url":null,"abstract":"\u0000 Theoretical modeling of a column type of direct contact heat exchanger was performed to predict the refrigerant evaporation and ice formation processes. There are a number of factors influencing the heat transfer rate-dependent evaporation of refrigerant and formation of ice. Among these are the size of the refrigerant droplets as injected, the local temperature and pressure, the heat transfer coefficient, and the temperature difference between the fluids. Differential equations are written for a general location in the flow, which express the conservation of energy and mass for the various species in the multiphase flow. The equations are solved stepwise from the initial injection location of the refrigerant to the location at which the entire refrigerant has become vapor. The theoretical modeling of the refrigerant evaporation and ice crystal growth processes is performed to determine the refrigerant bubble growth rate and the ice crystal growth rate in order to predict the refrigerant evaporation time and the size of the ice crystals.","PeriodicalId":369285,"journal":{"name":"Advances in Enhanced Heat Transfer","volume":"39 21","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131804464","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
Natural Convection From Horizontal Helicoidal Pipes 水平螺旋管的自然对流
Advances in Enhanced Heat Transfer Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1289
H. Al-Ahmadi, A. Fakheri
{"title":"Natural Convection From Horizontal Helicoidal Pipes","authors":"H. Al-Ahmadi, A. Fakheri","doi":"10.1115/imece2000-1289","DOIUrl":"https://doi.org/10.1115/imece2000-1289","url":null,"abstract":"\u0000 Natural convection heat transfer from a horizontal helicoidal pipe is experimentally investigated for different coil-pitches. A modified characteristic length incorporating the tube diameter, the coil diameter, and the coil spacing, is proposed as the relevant scale for defining Nusselt and Rayleigh numbers. Using the proposed characteristic length, it is shown that the Nusselt number for horizontal helicoidal pipes can be determined using the available Nusselt versus Rayleigh number correlation for straight horizontal cylinders with high degree of accuracy over the range of the experimental data.","PeriodicalId":369285,"journal":{"name":"Advances in Enhanced Heat Transfer","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116957797","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
Heat Transfer Enhancement for Finned-Tube Heat Exchangers With Winglets 带小翼翅片管换热器的强化传热研究
Advances in Enhanced Heat Transfer Pub Date : 2000-11-01 DOI: 10.1115/1.1842786
J. O'Brien, M. Sohal
{"title":"Heat Transfer Enhancement for Finned-Tube Heat Exchangers With Winglets","authors":"J. O'Brien, M. Sohal","doi":"10.1115/1.1842786","DOIUrl":"https://doi.org/10.1115/1.1842786","url":null,"abstract":"\u0000 This paper presents the results of an experimental study of forced convection heat transfer in a narrow rectangular duct fitted with a circular tube and/or a delta-winglet pair. The duct was designed to simulate a single passage in a fin-tube heat exchanger. Heat transfer measurements were obtained using a transient technique in which a heated airflow is suddenly introduced to the test section. High-resolution local fin-surface temperature distributions were obtained at several times after initiation of the transient using an imaging infrared camera. Corresponding local fin-surface heat transfer coefficient distributions were then calculated from a locally applied one-dimensional semi-infinite inverse heat conduction model. Heat transfer results were obtained over an airflow rate ranging from 1.51 × 10−3 to 14.0 × 10−3 kg/s. These flow rates correspond to a duct-height Reynolds number range of 670–6300 with a duct height of 1.106 cm and a duct width-to-height ratio, W/H, of 11.25. The test cylinder was sized such that the diameter-to-duct height ratio, D/H is 5. Results presented in this paper reveal visual and quantitative details of local fin-surface heat transfer distributions in the vicinity of a circular tube, a delta-winglet pair, and a combination of a circular tube and a delta-winglet pair. Comparisons of local and average heat transfer distributions for the circular tube with and without winglets are provided. Overall mean fin-surface Nusselt-number results indicate a significant level of heat transfer enhancement associated with the deployment of the winglets with the circular cylinder. At the lowest Reynolds numbers (which correspond to the laminar operating conditions of existing geothermal aircooled condensers), the enhancement level is nearly a factor of two. At higher Reynolds numbers, the enhancement level is close to 50%.","PeriodicalId":369285,"journal":{"name":"Advances in Enhanced Heat Transfer","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130073879","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: 37
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