Download or read book A Review on Convective Boiling Heat Transfer of Refrigerants in Horizontal Microfin Tubes written by Thanh Nhan Phan and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the Heat transfer performance of refrigerant for convective boiling in horizontal microfin tube and smooth tube is place an importance role on the designing of evaporator, the main equipment on refrigeration system. Reviewing the general concept especially the theory of boiling in the tube, the formation of the flow pattern map, the calculating procedure for heat transfer coefficient and pressure drop during boiling process of refrigerant in microfin tube. Besides, a typical example will be presented more detail in step by step to define the heat transfer coefficient and pressure drop for one working condition to estimate the data results without doing experiments.

Download or read book Horizontal Convective Boiling of Refrigerants and Refrigerant Mixtures Within a Micro Fin Tube written by nist and published by . This book was released on 2013-11-24 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents local convective boiling measurementsin a micro-fin tube for four pure refrigerants: R22, R32, R125, and R134a; and four refrigerant mixtures: R410B (R32/125, 45/55 % mass), R32/R134a (28/72 % and 30/70% mass) and, R407C (R32/125/134a, 25/23/52 % mass). Flow boiling heat transfer coefficients for the mixtures' pure components and R22 weremeasured to establish a baseline for the heat transfer degradation calculations. The measured convective boilingNusselt numbers for all of the test refrigerants were correlated to a single expression consisting of a product of dimensionless properties. The correlation was shown to predict some existing data from the literature within 20%. The degradation in heat transfer performance of the

Download or read book Horizontal Convective Boiling of R134a R1234yf R134a and R1234ze e Within Micro Fin Tube with Extensive Measurement and Analysis Details written by U.s. Department of Commerce and published by CreateSpace. This book was released on 2014-06-24 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Internally enhanced tubes, like the micro-fin tube, are used by most manufacturers in the construction of evaporators and condensers for new unitary refrigeration and air-conditioning equipment. The reason for the micro-fin tube's hold on unitary equipment is that it provides the highest heat transfer with the lowest pressure drop of the commercially available internal enhancements (Webb and Kim, 2005). Most of the experimental measurements for evaporative heat transfer coefficients in the micro-fin tube have been done for traditional refrigerants like R134a. Pressure from the policies set by the Montreal Protocol (1987), the Kyoto Protocol (1997) and the European Mobile Directive (2006) have caused a recent shift to refrigerants with both zero ozone depletion potential (ODP) and low global warming potential (GWP). Johnson et al. (2012) reports that azeotropic R1234yf/ R134a (56/44) (i.e., XP10) 1 and R1234ze(E) are among the low-GWP refrigerants identified for evaluation by the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) Low-GWP Alternative Refrigerants Evaluation Program as potential replacement refrigerants for R134a. The reason for this is that both R1234yf/ R134a (56/44) and R1234ze(E) have zero ODP and 100 year GWPs of approximately 600 and 6, respectively (Hickman, 2012 and Bitzer, 2012). Consequently, flow boiling heat transfer data for the micro-fin tube with R1234yf/ R134a (56/44) and R1234ze(E) are essential for the evaluation of their use for unitary applications.

Download or read book A Simple Correlation for Horizontal Micro fin Tube Convective Boiling with Example Calculation written by Mark A. Kedzierski and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents a simple correlation containing nine dimensionless parameters to predict the local convective boiling heat transfer within a micro-fin tube that was developed from a dataset that included a wide range of refrigerants, flow conditions, and hydraulic diameters. Flow boiling measurements from 36 studies were gathered to produce a dataset containing 29 refrigerants and 15 different hydraulic diameters ranging from 1.8 mm to 6.7 mm. The database was adjusted so that the definition of the Nusselt number, the Reynolds number, the heat flux, and heat transfer coefficient were all defined in the same way for each study. In addition, values for the most recent fluid properties were used for the calculation of dimensionless parameters that were used in the new correlation. The new correlation for micro-fin convective boiling predicted the measurements from the database to within 10.3 % for pure-refrigerants and azeotropic mixtures and 12.3 % for zeotropic mixtures.

Download or read book A Review on Condensation Process of Refrigerants in Horizontal Microfin Tubes written by Thanh Nhan Phan and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat transfer performance of refrigerant on the condensation process is very important in the designing of condensation equipment, especially in air conditioning and refrigeration systems. The outstanding advantages of microfin tubes are reducing the weight and size of condensers and also reducing the amount of refrigerant on the system. Reviewing the general concept of condensation and detailing the formation of flow pattern map that is also the procedure to determine heat transfer coefficient and pressure drop during condensation process of refrigerant inside the horizontal microfin tubes would be considered. Also, a typical example will be presented to illustrate a detailed procedure to calculate the value of heat transfer coefficient and pressure drop during the condensation process in horizontal microfin tubes. The data results show that microfin tube J60 with 60 number of fins inside 8.96 mm inner diameter, 0.2 mm height of fin, 40o of apex angle and 18o of helix angle, the condensation procedure of R1234ze at 35°C, heat flux of 8.62 kW/m2, and mass flux of 222 kg/m2s that could be estimated with heat transfer coefficient would be reduced from 8160.4 [W/m2 K] to 1413.8 [W/m2 K] follow with quality x changes from 0.99 to 0.01, and the maximum pressure drop of this process is 3173.8 [Pa/m].

Download or read book Horizontal Convective Boiling of R1234yf R134a and R450A Within a Micro fin Tube written by Mark A. Kedzierski and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents local convective boiling heat transfer and Fanning friction factor measurements in a micro-fin tube for R134a and two possible low global warming potential (GWP) refrigerant replacements for R134a: R1234yf and R450A. Test section heating was achieved with water in either counterflow or in parallel flow with the test refrigerant to provide for a range of heat fluxes for each thermodynamic quality. An existing correlation from the literature for single and multi-component mixtures was shown to not satisfactorily predict the convective boiling measurements for flow qualities greater than 40 %. Accordingly, a new correlation was developed specifically for the test fluids of this study so that a fair comparison of the heat transfer performance of the low GWP refrigerants to that of R134a could be made. The new correlation was used to compare the heat transfer coefficient of the three test fluids at the same heat flux, saturated refrigerant temperature, and refrigerant mass flux. The resulting example comparison, for the same operating conditions, showed that the heat transfer coefficient of the multi-component R450A and the single-component R1234yf were, on average, 15 % less and 5 % less, respectively, than that of the single-component R134a. Friction factor measurements were also compared to predictions from an existing correlation. A new correlation for the friction factor was developed to provide a more accurate prediction. The measurements and the new models are important for the evaluation of potential low-GWP refrigerants replacements for R134a.

Download or read book Horizontal Convective Boiling of R134a R1234yf r134a and R1234ze e Within a Micro fin Tube With Extensive Measurement and Analysis Details written by National Institute of Standards and Technology and published by CreateSpace. This book was released on 2014-02 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents local convective boiling measurements in a micro-fin tube for R134a and two low global warming potential (GWP ) refrigerants: R1234yf/ R134a, 56/44 % mass and R1234ze(E). Water heating either in counterflow or in parallel flow with the test refrigerant was used to vary the heat flux for a given quality. The heat transfer coefficient of the three test fluids were compared at the same heat flux, saturated refrigerant temperature, and refrigerant mass flux using an existing correlation from the literature. The resulting comparison showed that refrigerant R134a exhibited the highest heat transfer performance in large part due to its higher thermal conductivity as compared to the tested low-GWP refrigerants. For the example case presented here, the heat transfer coefficient for R1234yf/ R134a (56/44) remains within 5 % of the heat transfer coefficient for R134a, having essentially identical performance for qualities less than 30 %. The heat transfer coefficient for R1234ze(E) is roughly 700 kW, K-1, m-2 (approximately 14 %) less than that of R134a for qualities greater than 30 %. The smaller heat transfer coefficient of R1234ze(E) as compared to that of R134a is primarily due to the 11 % smaller thermal conductivity and the 21 % smaller reduced pressure as compared to R134a at this test temperature. The measurements are important as part of the evaluation of low-GWP replacement refrigerants for R134a in unitary refrigeration and air-conditioning equipmen

Download or read book Boiling written by Yasuo Koizumi and published by Elsevier. This book was released on 2017-06-22 with total page 849 pages. Available in PDF, EPUB and Kindle. Book excerpt: Boiling: Research and Advances presents the latest developments and improvements in the technologies, instrumentation, and equipment surrounding boiling. Presented by the Japan Society of Mechanical Engineers, the book takes a holistic approach, first providing principles, and then numerous practical applications that consider size scales. Through six chapters, the book covers contributed sections from knowledgeable specialists on various topics, ranging from outlining boiling phenomena and heat transfer characteristics, to the numerical simulation of liquid-gas two phase flow. It summarizes, in a single volume, the state-of-the-art in boiling heat transfer and provides a valuable resource for thermal engineers and practitioners working in the thermal sciences and thermal engineering. - Explores the most recent advancements in boiling research and technology from the last twenty years - Provides section content written by contributing experts in their respective research areas - Shares research being conducted and advancements being made on boiling and heat transfer in Japan, one of the major research hubs in this field

Download or read book Convective Boiling and Condensation written by John G. Collier and published by Clarendon Press. This book was released on 1994-05-19 with total page 646 pages. Available in PDF, EPUB and Kindle. Book excerpt: * Third edition of a well-known and well established text both in industry and for teaching * Fully up-to-date and includes extra problems This book is an aid to heat exchanger design written primarily for design and development engineers in the chemical process, power generation, and refrigeration industries. It provides a comprehensive reference on two-phase flows, boiling, and condensation. The text covers all the latest advances like flows over tube bundles and two-phase heat transfer regarding refrigerants and petrochemicals. Another feature of this third edition is many new problems at chapter ends to enhance its use as a teaching text for graduate and post-graduate courses on two-phase flow and heat transfer. - ;This book is written for practising engineers as a comprehensive reference on two-phase flows, boiling, and condensation. It deals with methods for estimating two-phase flow pressure drops and heat transfer rates. It is a well-known reference book in its third edition and is also used as a text for advanced university courses. Both authors write from practical experience as both are professional engineers. -

Download or read book Convective Boiling and Condensation written by John Gordon Collier and published by McGraw-Hill International Book Company. This book was released on 1981 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt: On its original publication in 1973, this book was the first reference for engineers to fully present the science of boiling and condensation. It dealt especially with the problems of estimating heat transfer rates and pressure drops, with particular attention to the occurrence of boiling and condensation in the presence of forced flows within pipes. The new third edition was written primarily for design and development engineers in the chemical process, power generation, and refrigeration industries, and is meant to be an aid in the design of heat exchangers. It covers recent advances and significantly broadens coverage to flows over tube bundles, with extensive new treatment of two-phase heat transfer regarding refrigerants and petrochemicals. Many new problems have been added at the end of each chapter to enhance the book's use as a text in advanced courses on two-phase flow and heat transfer. Instructors using the book as a course text may obtain full solutions to the end-of-chapter problems by writing to: Science Marketing Dept., Oxford University Press, 198 Madison Avenue, New York, NY 10016 (please include school name and course identification), or by faxing (212) 726-6442.

Download or read book Heat Transfer and Pressure Drop in Forced Convection Boiling of Refrigerant Mixture Inside Horizontal Tubes written by L. C. Singal and published by . This book was released on 1983 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heat Transfer and Fluid Flow in Minichannels and Microchannels written by Satish Kandlikar and published by Elsevier. This book was released on 2006 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: &Quot;This book explores flow through passages with hydraulic diameters from about 1 [mu]m to 3 mm, covering the range of minichannels and microchannels. Design equations along with solved examples and practice problems are also included to serve the needs of practicing engineers and students in a graduate course."--BOOK JACKET.

Download or read book Horizontal Convective Condensation of Alternative Refrigerants Within a Micro Fin Tube Classic Reprint written by Mark a Kedzierski and published by Forgotten Books. This book was released on 2017-10-28 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: Excerpt from Horizontal Convective Condensation of Alternative Refrigerants Within a Micro-Fin Tube As shown in Fig. 3, six refrigerant pressure taps along the test section allowed the measurement of the upstream absolute pressure and five pressure drops along the test section. Two sets of two water pressure taps were used to measure the water pressure drop along each tube. Also, a sheathed thermocouple measured the refrigerant temperature at each end of the two refrigerant tubes, with the junction of each centered radially. Only the thermocouple at the inlet of the first tube was used in the calculations. Theentire test section was wrapped with 5 cm of foam insulation to minimize heat transfer between the water and the ambient. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.

Download or read book Heat Exchangers written by Laura Castro Gómez and published by BoD – Books on Demand. This book was released on 2022-03-23 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: The demand for energy to satisfy the basic needs and services of the population worldwide is increasing as are the economic costs associated with energy production. As such, it is essential to emphasize energy recovery systems to improve heat transfer in thermal processes. Currently, significant research efforts are being conducted to expose criteria and analysis techniques for the design of heat exchange equipment. This book discusses optimization of heat exchangers, heat transfer in novel working fluids, and the experimental and numerical analysis of heat transfer applications.

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 Horizontal Convective Boiling of Refrigerants and Refrigerant Mixtures Within a Micro fin Tube written by Louis John Hamilton and published by . This book was released on 2005 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Boiling Heat Transfer of Refrigerant R 113 in a Small diameter Horizontal Tube written by and published by . This book was released on 1992 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of a study of boiling heat transfer from refrigerant R-113 in a small-diameter (2.92-mm) tube are reported. Local heat transfer coefficients over a range of heat fluxes, mass fluxes, and equilibrium mass qualities were measured. The measured coefficients were used to evaluate eight different heat transfer correlations, some of which have been developed specifically for refrigerants. High heat fluxes and low flow rates are inherent in small channels, and this combination results in high boiling numbers. The high boiling number of the collected data shows that the nucleation mechanism was dominant. As a result, the two-phase correlations that predicted this dominance also predicted the data best if they also properly modeled the physical parameters. The correlations of Lazarek and Black and of Shah, as modified in this study, predicted the data very well. It is also shown that a simple form, suggested by Stephan and Abdelsalam for nucleate boiling, correlates the data equally well. This study is part of a research program in multiphase flow and heat transfer, with the overall objective of developing validated design correlations and predictive methods that will facilitate the design and optimization of compact heat exchangers for use with environmentally acceptable alternatives for chlorofluorocarbon (CFC) refrigerants and refrigerant mixtures.