Download or read book Application of Diffusion Layer Theory to Vertical Downflow Condensation Heat Transfer written by Takao Kageyama and published by . This book was released on 1992 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dropwise Condensation as Affected by Vapor Diffusion and Molecular Sticking written by Salil Kumar Banerjee and published by . This book was released on 1974 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Condensation from Vapor gas Mixture for Forced Downflow Inside a Tube written by Ruey Yng Yuann and published by . This book was released on 1993 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Vertical Downflow Condensation Heat Transfer in Gas steam Mixtures written by Daniel Grant Ogg and published by . This book was released on 1991 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 836 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of Heat Transfer from Condensing Steam gas Mixtures and Turbulent Films Flowing Downward Inside a Vertical Tube written by Shine-Zen Kuhn and published by . This book was released on 1995 with total page 732 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heat Transfer in Condensation and Boiling written by Karl Stephan and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: I welcome the opportunity to have my book translated, because of the great emphasis on two-phase flow and heat transfer in the English-speaking world, as related to research, university education, and industrial practice. The 1988 Springer-Verlag edition of "Warmeiibergang beim Kondensieren und beim Sieden" has been enlarged to include additional material on falling film evaporation (Chapter 12) and pressure drop in two-phase flow (Chapter 13). Minor errors in the original text have also been corrected. I would like to express my sincere appreciation to Professor Green, Asso ciate Professor of German at Rensselaer, for his excellent translation and co operation. My thanks go also to Professor Bergles for his close attention to technical and linguistic details. He carefully read the typescript and made many comments and suggestions that helped to improve the manuscript. I hope that the English edition will meet with' a favorable reception and contribute to better understanding and to progress in the field of heat transfer in condensation and boiling. February 1992 K. Stephan Preface to the German-Language Edition This book is a continuation of the series "Heat and Mass Transfer" edited by U. Grigull, in which three volumes have already been published. Its aim is to acquaint students and practicing engineers with heat transfer during condensa tion and boiling, and is intended primarily for students and engineers in mechanical, chemical, electrical, and industrial processing engineering.

Download or read book Drop Dynamics and Dropwise Condensation on Textured Surfaces written by Sameer Khandekar and published by Springer Nature. This book was released on 2020-09-11 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an expanded form of the monograph, Dropwise Condensation on Inclined Textured Surfaces, Springer, 2013, published earlier by the authors, wherein a mathematical model for dropwise condensation of pure vapor over inclined textured surfaces was presented, followed by simulations and comparison with experiments. The model factored in several details of the overall quasi-cyclic process but approximated those at the scale of individual drops. In the last five years, drop level dynamics over hydrophobic surfaces have been extensively studied. These results can now be incorporated in the dropwise condensation model. Dropwise condensation is an efficient route to heat transfer and is often encountered in major power generation applications. Drops are also formed during condensation in distillation devices that work with diverse fluids ranging from water to liquid metals. Design of such equipment requires careful understanding of the condensation cycle, starting from the birth of nuclei, followed by molecular clusters, direct growth of droplets, their coalescence, all the way to instability and fall-off of condensed drops. The model described here considers these individual steps of the condensation cycle. Additional discussions include drop shape determination under static conditions, a fundamental study of drop spreading in sessile and pendant configurations, and the details of the drop coalescence phenomena. These are subsequently incorporated in the condensation model and their consequences are examined. As the mathematical model is spread over multiple scales of length and time, a parallelization approach to simulation is presented. Special topics include three-phase contact line modeling, surface preparation techniques, fundamentals of evaporation and evaporation rates of a single liquid drop, and measurement of heat transfer coefficient during large-scale condensation of water vapor. We hope that this significantly expanded text meets the expectations of design engineers, analysts, and researchers working in areas related to phase-change phenomena and heat transfer.

Download or read book Theory of Laminar Film Condensation written by Tetsu Fujii and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 225 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the petroleum crisis in the 1970s, a lot of effort to save energy was made in industry, and remarkable achievements have been made. In the research and development concerning thermal energy, however, it was clar ified that one of the most important problems was manufacturing con densing systems with smaller size and higher performance. To solve this problem we need a method which synthesizes selections_ of the type of con denser, cooling tube and its arrangement, assessment of fouling on the cooling surfaces, consideration of transient characteristics of a condenser, etc. The majority of effort, however, has been to devise a surface element which enhances the heat transfer coefficient in condensation of a single or multicomponent vapor. Condensation phenomena are complexly affected by a lot of physical property values, and accordingly the results of theo retical research are expressed with several dimensionless parameters. On the other hand, the experimental research is limited to those with some specified cooling surfaces and some specified working fluids. Hence, the basic research of condensation is necessary for criticizing the enhancement effect as well as for an academic interest.

Download or read book Condensation Heat Transfer written by P. J. Marto and published by . This book was released on 1979 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Investigation of Condensation from Steam gas Mixtures Flowing Downward Inside a Vertical Tube written by and published by . This book was released on 1995 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous experiments have been carried out by Vierow, Ogg, Kageyama and Siddique for condensation from steam/gas mixtures in vertical tubes. In each case the data scatter relative to the correlation was large and there was not close agreement among the three investigations. A new apparatus has been designed and built using the lessons learned from the earlier studies. Using the new apparatus, an extensive new data base has been obtained for pure steam, steam-air mixtures and steam-helium mixtures. Three different correlations, one implementing the degradation method initially proposed by Vierow and Schrock, a second diffusion layer theory initially proposed by Peterson, and third mass transfer conductance model are presented in this paper. The correlation using the simple degradation factor method has been shown, with some modification, to give satisfactory engineering accuracy when applied to the new data. However, this method is based on very simplified arguments that do not fully represent the complex physical phenomena involved. Better representation of the data has been found possible using modifications of the more complex and phenomenologically based method which treats the heat transfer conductance of the liquid film in series with the conductance on the vapor-gas side with the latter comprised of mass transfer and sensible heat transfer conductance acting in parallel. The mechanistic models, based on the modified diffusion layer theory or classical mass transfer theory for mass transfer conductance with transpiration successfully correlate the data for the heat transfer of vapor-gas side. Combined with the heat transfer of liquid film model proposed by Blangetti, the overall heat transfer coefficients predicted by the correlations from mechanistic models are in close agreement with experimental values.

Download or read book Nuclear Science and Engineering written by and published by . This book was released on 1995 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1972 with total page 542 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Active Augmentation of Condensation written by Ali Mohammad A Alshehri and published by . This book was released on 2021 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: Condensation is a very complicated subject to fully unveil as it constitutes a complex interplay of momentum, heat and species transport and interfacial physics. Drop-wise condensation (DWC) adds more layers of complexity by introducing droplet dynamics and the two-way interaction with droplets surrounding. DWC has been shown repeatedly for about a century to possess around an order of magnitude improved heat transfer rates. Additionally, it has been shown that DWC is limited by the maximum size of droplets a surface sustains. Since this realization, promoting DWC has been greatly steered towards developing stable hydrophobic coating techniques. However, attempts have not been feasible so far especially due to the extreme conditions encountered in condensation processes. Another concern that has not been resolved adequately is the deterioration of heat and condensation rates due to the presence of non-condensable gases (NCG). This dissertation aims at understanding the process of condensation especially in the presence of NCG. First, a numerical model of the process of vapor condensation on surfaces characterized by film-wise condensation with the presence of (NCG) is presented. State variables in both the condensate film and the diffusion layer were solved separately and the condensation interface was used to couple the two solutions. The solution of the condensate film was obtained using well-established solutions of laminar film condensation of pure vapor. In contrast to other models surveyed, this work provides a inexpensive and accurate predictions of heat and mass transfer characteristics. We validated the work against two classical condensation problems. The model was first validated against empirical correlations and experimental work, resulting in a very good agreement. We then assessed the applicability of ignoring the condensate film effect, as performed in previous models, on the condensation processes by observing the thermal resistances of both the condensate film and diffusion layer. Results indicated that for the studied cases of NCG mass fractions above 20\%, the condensate thermal resistance was at least an order of magnitude lower than that of the diffusion layer. However, the two thermal resistances seem to approach each other as NCG mass fraction becomes smaller. On another front, we observed that models that ignore the condensate film thermal resistance underestimate the interfacial temperature albeit accurately predicting the overall heat transfer rate. To simulate even lower NCG mass fractions, we validated our model to the classical analytical work of Sparrow and co-workers. Results showed an excellent agreement between the two solutions at different NCG mass fractions (0.5\%-10\%) and subcooling degrees (5$^o$F-40$^o$F). Finally, we found a good agreement between results of our model and the heat/mass transfer analogy. The heat/mass transfer analogy is a semi-empirical method therefore, is limited to the existing correlations and their uncertainties. On the other hand, our model does not use any empiricism and relies on the available solutions of laminar condensate film of pure vapor in predicting the liquid side heat transfer coefficient. Moreover, motivated by the improvement in heat transfer by frequently disturbing the thermal boundary layer in nucleate boiling phenomenon, we attempted making the analogy to DWC. We developed an initial theoretical model to predict the transience of the diffusion boundary layer in condensation problems with NCG presence. The problem of suddenly exposing a cooled surface to a humid environment was modeled as two semi-infinite gas and solid domains in contact with the condensate film as a coupling condition. Results showed that the transient behavior of heat and condensation rates start by very high values and then decrease to steady state rates. This suggested that if the diffusion layer is frequently disturbed by droplets of heights similar to the layer's thickness, the condensation rate is expected to improve. To realize this, jet impingement of humidified air was proposed as a means of thinning the diffusion layer as well as to provide better shedding capabilities of condensate droplets. Finally, Utilizing jet impingement technique as a means for continuous drop-wise condensation (CDC) was investigated. The technique showed an advantage of overcoming the necessity of using highly non-wetting surfaces while yet maintaining micron-sized droplets. By shifting focus from surface treatment to the force required to sweep off a droplet, we were able to utilize stagnation pressure of jet impingement to tune the shed droplet size. To demonstrate the effectiveness of this technique, we performed condensation experiments on a broad range of contact angle and contact angle hysteresis surfaces. The results showed that droplet size being shed can be tuned effectively by tuning the jet parameters namely the jet Reynolds number. Droplets as low as 20 $\mu$m in radius on a hydrophilic surface were shed with this technique surpassing the traditional gravity-assisted shedding mechanism by almost 80 folds. In terms of condensation rate improvement, we showed theoretically that CDC improves the condensation rate of pure steam, and hence heat transfer rate, by more than 300\% compared to gravity-assisted shedding DWC. Finally, our experimental observations showed that the effect of NCG, such as air in this work, is greatly alleviated by utilizing our technique. An improvement by at least six folds in mass transfer compactness factor compared to state-of-the-art dehumidification technology was possible. We illustrated the physics of droplet departure and mobility due to the stagnation flow condition by microscopically tracing a single droplet.

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1976 with total page 680 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook of Thermal Science and Engineering written by and published by Springer. This book was released on 2018-07-31 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Handbook provides researchers, faculty, design engineers in industrial R&D, and practicing engineers in the field concise treatments of advanced and more-recently established topics in thermal science and engineering, with an important emphasis on micro- and nanosystems, not covered in earlier references on applied thermal science, heat transfer or relevant aspects of mechanical/chemical engineering. Major sections address new developments in heat transfer, transport phenomena, single- and multiphase flows with energy transfer, thermal-bioengineering, thermal radiation, combined mode heat transfer, coupled heat and mass transfer, and energy systems. Energy transport at the macro-scale and micro/nano-scales is also included. The internationally recognized team of authors adopt a consistent and systematic approach and writing style, including ample cross reference among topics, offering readers a user-friendly knowledgebase greater than the sum of its parts, perfect for frequent consultation. The Handbook of Thermal Science and Engineering is ideal for academic and professional readers in the traditional and emerging areas of mechanical engineering, chemical engineering, aerospace engineering, bioengineering, electronics fabrication, energy, and manufacturing concerned with the influence thermal phenomena.

Download or read book Convective Mass Transfer written by Dudley Brian Spalding and published by . This book was released on 1963 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt: