Download or read book Fully Developed Forced Convection Heat Transfer and Pressure Drop in a Smooth Tube in the Transitional Flow Regime written by Nicola Mary Van der Merwe and published by . This book was released on 2017 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: Extensive work has been done on characterising convective heat transfer and pressure drop in smooth tubes in the laminar and turbulent flow regimes. However, little work was completed in the transitional flow regime. In all previous transitional studies, experiments that were conducted between the laminar and turbulent flow regimes were with mixed convection in the laminar flow regime and not in the forced convection flow regime. The secondary flow that occurs during mixed convection should most probably influence the characteristics in the transitional flow regime. It can therefore be expected that the transitional flow characteristics of forced convection and mixed convection will be different. However, the transitional characteristics of forced convection flow have not yet been determined. The purpose of this study was therefore to determine the heat transfer and pressure drop transitional characteristics specifically in the forced convection flow regime. Furthermore, to focus on determining these factors for a circular, horizontal smooth tube for fully developed flow. The characteristics were determined in an experimental set-up through which flow occurred through a test section consisting of a horizontal and circular smooth tube. The test-section inside diameter was 4.04 mm, and the tube length was 8.4 m. Water was used as the test fluid and was circulated through the test section which was heated at a constant heat flux. A calming section with a square edge inlet was upstream of the test section. Temperatures at the tube inlet, outlet and outer surface of the test section were measured with a total of 58 thermocouples. Two pressure taps was also installed on the test section and was connected to a pressure transducer for pressure drop measurements. Experiments were conducted mainly on the last part of the test section where fully developed flow occurred. Experiments were conducted between Reynolds numbers of 1 000 to 10 000, Prandtl numbers of 3 to 8, and Rayleigh numbers of 330 and 11 000 (heat fluxes of 0.89 kW/m2 to 3.26 kW/m2). It was found that the heat transfer transitional range coincided with the friction factor transition range with a Reynolds number range of 2 484 to 2 849. Forced convection results in the laminar regime was achieved and compared well to literature. The results were mapped on published flow regime maps. This was inconclusive as the published flow regime maps have been specifically developed for fixed parameters that did not match the parameters of this study..

Download or read book Single phase Mixed Convection of Developing and Fully Developed Flow in Smooth Horizontal Tubes in the Laminar Transitional Quasi turbulent and Turbulent Flow Regimes written by Marilize Everts and published by . This book was released on 2017 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: The laminar and turbulent flow regimes have been extensively investigated from as early as 1883, and research has been devoted to the transitional flow regime since the 1990s. However, there are several gaps in the mixed convection literature, especially when the flow is still developing. The purpose of the study was to experimentally investigate the heat transfer and pressure drop characteristics of developing and fully developed flow of low Prandtl number fluids in smooth horizontal tubes for forced and mixed convection conditions. An experimental set-up was designed and built, and results were validated against literature. Two smooth circular test sections with inner diameters of 4 mm and 11.5 mm were used, and the maximum length-to-diameter ratios were 1 373 and 872 respectively. Heat transfer measurements were taken at Reynolds numbers between 500 and 10 000 at different constant heat fluxes. A total of 648 mass flow rate measurements, 70 301 temperature measurements and 2 536 pressure drop measurements were taken. Water was used as the test fluid and the Prandtl number ranged between 3 and 7. It was found that a longer thermal entrance length was required for simultaneously hydrodynamically and thermally developing flow. Therefore, a coefficient of at least 0.12 (and not 0.05 as advised in most literature) was suggested. Because free convection effects decreased the thermal entrance length, correlations were also developed to calculate the thermal entrance length for mixed convection conditions. The boundaries between the flow regimes were defined mathematically, and terminology to define transitional flow characteristics was presented. For laminar flow, three different regions (forced convection developing, mixed convection developing and fully developed) were identified in the local heat transfer results and nomenclature and correlations were developed to define and quantify the boundaries of these regions. Correlations were also developed to calculate the local and average laminar Nusselt numbers of mixed convection developing flow. The laminar-turbulent transition along the tube length occurred faster with increasing Reynolds number, and was also influenced by free convection effects. As free convection effects became significant, the effect was first to disrupt the fluctuations inside the test section, leading to a slower laminar-turbulent transition along the tube length compared with forced convection conditions. However, as free convection effects were increased, the fluctuations inside the test section increased and caused the laminar-turbulent transition along the tube length to occur faster. The Reynolds number at which transition started was found to be independent of axial position for both developing and fully developed flow. However, the end of transition occurred earlier as the flow approached fully developed flow. When the flow was fully developed, the end of transition became independent of axial position. Furthermore, free convection effects affected both the start and end of the transitional flow regime, and caused the Reynolds number range of the transitional flow regime to decrease. Correlations were therefore developed to determine the start and end of the transitional flow regime for developing and fully developed flow in mixed convection conditions. The transitional flow regime across the tube length was divided into three regions. In the first region, the width of the transitional flow regime decreased significantly with axial position as the thermal boundary layer thickness increased, and free convection effects were negligible. In Region 2, the width of the transitional flow regime decreased with axial position, due to the development of the thermal boundary layer, as well as with increasing free convection effects. In the fully developed region (Region 3), the width of the transitional flow regime was independent of axial position, but decreased significantly with increasing free convection effects. At high Grashof numbers, free convection effects even caused the transitional flow regime of fully developed flow to become negligible. It was found that the boundaries of the different flow regimes were the same for pressure drop and heat transfer, and a relationship between pressure drop and heat transfer existed in all four flow regimes. In the laminar flow regime, this relationship was a function of Grashof number (thus free convection effects), while it was a function of Reynolds number in the other three flow regimes. Correlations to predict the average Nusselt numbers, as well as the friction factors as a function of average Nusselt number, for developing and fully developed flow in all flow regimes were developed. Finally, flow regime maps were developed to predict the convection flow regime for developing and fully developed flow for a wide range of tube diameters and Prandtl numbers, and these flow regime maps were unique for four reasons. Firstly, they contained contour lines that showed the Nusselt number enhancements due to the free convection effects. Secondly, they were valid for a wide range of tube diameters and Prandtl numbers. Thirdly, the flow regime maps were developed as a function of temperature difference (Grashof number) and heat flux (modified Grashof number). Finally, four of the six flow regime maps were not only valid for fully developed flow, but also for developing flow.

Download or read book Single phase Forced and Mixed Convection in the Laminar and Transitional Flow Regimes of Inclined Smooth Tubes with Inlet Disturbances written by Abubakar Idris Bashir and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Laminar and transitional flow regimes in tubes have been extensively investigated in the literature. However, there are several gaps in the forced and mixed convection literature, especially for inclined tubes with different inlet disturbances. The purpose of this study was to experimentally investigate the effect of tube inclination and inlet contraction ratio on the single-phase heat transfer and pressure drop characteristics in the laminar and transitional flow regimes for pure forced and mixed convection conditions. An experimental set-up was designed, constructed and validated against literature with the test section in a horizontal and different vertical orientation. The test section was 4.6 m long and was made from a smooth hard drawn copper tube with measured inner and outer diameters of 5.1 mm and 6.3 mm, respectively. Experiments were conducted at various inclination angles from vertical upward flow (+90AÌ2℗ð) to vertical downward flow (aÌ22́Ơ0́−90AÌ2℗ð), with horizontal flow (0AÌ2℗ð) and several other angles in between. A total of 2 679 mass flow rate measurements, 174 135 temperature measurements and 2 679 pressure drop measurements were conducted using water (Prandtl numbers between 3.5 and 8.1) as working fluid. The Reynolds number range covered were from 400 to 6 000 at constant heat fluxes varying from 1 to 8 kW/m2. Four different types of inlets namely; square-edged and re-entrant inlet with different inlet contraction ratios (5, 11, 14 and 33), as well as hydrodynamically fully developed and 90AÌ2℗ð bend inlets were used. It was found that an increase in the inclination angle from horizontal flow (0AÌ2℗ð) to vertical (AÌ2℗ł90AÌ2℗ð) flow, decreased the buoyancy effects which led to decreased laminar heat transfer coefficients and friction factors for both upward and downward flows. The onset of buoyancy effects was significant near the vertical inclination angles and caused a rapid increase in the laminar heat transfer coefficients and friction factors when the inclination angles moved from vertical to horizontal orientations. An inclined tube Grashof number which is a function of inclination angle was defined and used to express the laminar Nusselt numbers as a forced convection part plus an enhancement component owing to mixed convection. The laminar friction factors were expressed as a function of a forced convection/isothermal part multiplied by the mixed convection part. Furthermore, it was found that the critical Reynolds numbers at which transitional flow regime started increased as the inclination angles increased from horizontal to vertical, while the end of transitional flow regime were inclination angle independent. This caused the width of the transitional flow regime to decrease, as well as the transition gradients to increase, with increasing inclination angles at different heat fluxes. It was also found that the flow directions (upward and downward) had a negligible effect on the heat transfer coefficients and friction factors in the entire transition and quasi-turbulent regions. The fully developed laminar forced convection Nusselt numbers were not constant at 4.36, but were a function of Reynolds number for Reynolds numbers higher than 1 000. Therefore, a revised laminar Nusselt number correlation for smooth circular tubes was developed. The fully developed laminar forced convection friction factors were, as expected, equal to 64/Re. For both the forced convection heat transfer and pressure drop characteristics, transition occurred at the same mass flow rates for all the heat fluxes, including isothermal flow, but the critical Reynolds numbers increased with an increase in heat flux. For forced convection condition, the width of the transitional flow regime in the fully developed region remained constant for all heat fluxes. For a square-edged inlet geometry, the transition from the laminar to the turbulent flow regimes occurred earlier as the inlet contraction ratio increased, while for the re-entrant inlet, transition was delayed. The transitional flow regime was significantly affected by smaller contraction ratios and this effect increased with increasing heat flux. However, it was found that the critical Reynolds numbers were independent of inlet geometry for contraction ratios larger than 33. For the 90AÌ2℗ð bend inlet, transition occurred earlier than all the other inlet geometries and contraction ratios.

Download or read book Fluid Mechanics and Fluid Power Vol 3 written by Suvanjan Bhattacharyya and published by Springer Nature. This book was released on 2023-04-17 with total page 628 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the select proceedings of the 48th National Conference on Fluid Mechanics and Fluid Power (FMFP 2021) held at BITS Pilani in December 2021. It covers the topics such as fluid mechanics, measurement techniques in fluid flows, computational fluid dynamics, instability, transition and turbulence, fluid‐structure interaction, multiphase flows, micro- and nanoscale transport, bio-fluid mechanics, aerodynamics, turbomachinery, propulsion and power. The book will be useful for researchers and professionals interested in the broad field of mechanics.

Download or read book Heat Transfer and Pressure Drop of Developing Flow in Smooth Tubes in the Transitional Flow Regime written by Marilize Everts and published by . This book was released on 2014 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat exchangers have a wide range of applications and engineers need accurate correlations to optimise the design of these heat exchangers. During the design process, the best compromise between high heat transfer coefficients and relatively low pressure drops is usually in the transitional flow regime. Limited research has been done on tube flow in the transitional flow regime. These studies considered either fully developed flow, or average measurements of developing flow across a tube length. No research has been done with the focus on developing flow in smooth tubes in the transitional flow regime. Therefore, the purpose of this study was to experimentally investigate the heat transfer and pressure drop characteristics of developing flow in the transitional flow regime. An experimental set-up was designed, built and validated against literature. Heat transfer and pressure drop measurements were taken at Reynolds numbers between 500 and 10 000 at three different heat fluxes (6.5, 8.0 and 9.5 kW/m2). A total of 398 mass flow rate measurements, 19 158 temperature measurements and 370 pressure drop measurements were taken. Water was used as the test fluid and the Prandtl number ranged between 3 and 7. The test section was a smooth circular tube and had an inner diameter and length of 11.52 mm and 2.03 m, respectively. An uncertainty analysis showed that the uncertainties of the Nusselt numbers and Colburn j-factors varied between 4% and 5% while the friction factor uncertainties varied between 1% and 17%. Five different flow regimes (laminar, developing laminar, transitional, low-Reynolds-number-end and turbulent) were identified in the first part of the tube during the experiments and nomenclature was developed to more clearly identify the boundaries of the different flow regimes. The developing laminar regime was unique to developing flow and decreased along the tube length. Both the start and end of transition were delayed along the tube length and the width of the transition region decreased slightly. This is in contrast with the results obtained in literature where the effect of the non-dimensional distance from the inlet on fully developed flow in the transition region was investigated. Transition was also slightly delayed with increasing heat flux, but secondary flow effects had no significant influence on the width of the transition region. The relationship between heat transfer and pressure drop was investigated and correlations were developed to predict the Nusselt number as a function of friction factor, Reynolds number and Prandtl number in the laminar, transitional, low-Reynolds-number-end and turbulent flow regimes. Overall, it can be concluded that the heat transfer characteristics of developing and fully developed flow differ significantly and more work needs to be done to fully understand the fundamentals before the heat transfer and pressure drop characteristics are fully understood.

Download or read book Introduction to Convective Heat Transfer written by Nevzat Onur and published by John Wiley & Sons. This book was released on 2023-04-18 with total page 805 pages. Available in PDF, EPUB and Kindle. Book excerpt: INTRODUCTION TO CONVECTIVE HEAT TRANSFER A highly practical intro to solving real-world convective heat transfer problems with MATLAB® and MAPLE In Introduction to Convective Heat Transfer, accomplished professor and mechanical engineer Nevzat Onur delivers an insightful exploration of the physical mechanisms of convective heat transfer and an accessible treatment of how to build mathematical models of these physical processes. Providing a new perspective on convective heat transfer, the book is comprised of twelve chapters, all of which contain numerous practical examples. The book emphasizes foundational concepts and is integrated with explanations of computational programs like MATLAB® and MAPLE to offer students a practical outlet for the concepts discussed within. The focus throughout is on practical, physical analysis rather than mathematical detail, which helps students learn to use the provided computational tools quickly and accurately. In addition to a solutions manual for instructors and the aforementioned MAPLE and MATLAB® files, Introduction to Convective Heat Transfer includes: A thorough introduction to the foundations of convective heat transfer, including coordinate systems, and continuum and thermodynamic equilibrium concepts Practical explorations of the fundamental equations of laminar convective heat transfer, including integral formulation and differential formulation Comprehensive discussions of the equations of incompressible external laminar boundary layers, including laminar flow forced convection and the thermal boundary layer concept In-depth examinations of dimensional analysis, including the dimensions of physical quantities, dimensional homogeneity, and dimensionless numbers Ideal for first-year graduates in mechanical, aerospace, and chemical engineering, Introduction to Convective Heat Transfer is also an indispensable resource for practicing engineers in academia and industry in the mechanical, aerospace, and chemical engineering fields.

Download or read book Advances in Heat Transfer written by and published by Academic Press. This book was released on 2019-10-24 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Heat Transfer, Volume 51, provides in-depth review articles from a broader scope than in traditional journals or texts, with this comprehensive release covering chapters on Micro and nanoparticle transport phenomena in confined flows, A review of heat transfer in the transitional flow regime, and much more. - Fills the information gap between regularly scheduled journals and university-level textbooks by providing in-depth review articles over a broader scope than in traditional journals or texts - Provides essential reading for all mechanical, chemical and industrial engineers working in the field of heat transfer - Presents a great resource for use in graduate school level courses

Download or read book The Art of Measuring in the Thermal Sciences written by Josua Meyer and published by CRC Press. This book was released on 2020-11-05 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Art of Measuring in the Thermal Sciences provides an original state-of-the-art guide to scholars who are conducting thermal experiments in both academia and industry. Applications include energy generation, transport, manufacturing, mining, processes, HVAC&R, etc. This book presents original insights into advanced measurement techniques and systems, explores the fundamentals, and focuses on the analysis and design of thermal systems. Discusses the advanced measurement techniques now used in thermal systems Links measurement techniques to concepts in thermal science and engineering Draws upon the original work of current researchers and experts in thermal-fluid measurement Includes coverage of new technologies, such as micro-level heat transfer measurements Covers the main types of instrumentation and software used in thermal-fluid measurements This book offers engineers, researchers, and graduate students an overview of the best practices for conducting sound measurements in the thermal sciences.

Download or read book Fundamentals of Forced Convection Heat Transfer written by American Society of Mechanical Engineers. Winter Annual Meeting and published by American Society of Mechanical Engineers. This book was released on 1991 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Technology of Forced Flow and Once through Boiling written by Heinz Frank Poppendiek and published by . This book was released on 1975 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heat Transfer Handbook written by Adrian Bejan and published by John Wiley & Sons. This book was released on 2003-06-30 with total page 1496 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chapters contributed by thirty world-renown experts. * Covers all aspects of heat transfer, including micro-scale and heat transfer in electronic equipment. * An associated Web site offers computer formulations on thermophysical properties that provide the most up-to-date values.

Download or read book Handbook of Single Phase Convective Heat Transfer written by Sadik Kakaç and published by Wiley-Interscience. This book was released on 1987-11-03 with total page 1268 pages. Available in PDF, EPUB and Kindle. Book excerpt: Very Good,No Highlights or Markup,all pages are intact.

Download or read book Progress in Food Engineering Research and Development written by Jerrod M. Cantor and published by Nova Publishers. This book was released on 2008 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents new and significant research in the growing field of food engineering which refers to the engineering aspects of food production and processing. Food engineering includes, but is not limited to, the application of agricultural engineering and chemical engineering principles to food materials. Genetic engineering of plants and animals is not normally the work of a food engineer. Food engineering is a very wide field of activities. Among its domain of knowledge and action are: Design of machinery and processes to produce foods; Design and implementation of food safety and preservation measures in the production of foods; Biotechnological processes of food production; Choice and design of food packaging materials; Quality control of food production.

Download or read book Heat and Mass Transfer written by Rajendra Karwa and published by Springer Nature. This book was released on 2020-06-18 with total page 1162 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook presents the classical treatment of the problems of heat transfer in an exhaustive manner with due emphasis on understanding of the physics of the problems. This emphasis will be especially visible in the chapters on convective heat transfer. Emphasis is also laid on the solution of steady and unsteady two-dimensional heat conduction problems. Another special feature of the book is a chapter on introduction to design of heat exchangers and their illustrative design problems. A simple and understandable treatment of gaseous radiation has been presented. A special chapter on flat plate solar air heater has been incorporated that covers mathematical modeling of the air heater. The chapter on mass transfer has been written looking specifically at the needs of the students of mechanical engineering. The book includes a large number and variety of solved problems with supporting line diagrams. A number of application-based examples have been incorporated where applicable. The end-of-chapter exercise problems are supplemented with stepwise answers. Though the book has been primarily designed to serve as a complete textbook for undergraduate and graduate students of mechanical engineering, it will also be useful for students of chemical, aerospace, automobile, production, and industrial engineering streams. The book fully covers the topics of heat transfer coursework and can also be used as an excellent reference for students preparing for competitive graduate examinations.

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1967 with total page 686 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design and Operation of Heat Exchangers and their Networks written by Wilfried Roetzel and published by Academic Press. This book was released on 2019-10-04 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt: Design and Operation of heat Exchangers and Their Networks presents a comprehensive and detailed analysis on the thermal design methods for the most common types of heat exchangers, with a focus on their networks, simulation procedures for their operations, and measurement of their thermal performances. The book addresses the fundamental theories and principles of heat transfer performance of heat exchangers and their applications and then applies them to the use of modern computing technology. Topics discussed include cell methods for condensers and evaporators, dispersion models for heat exchangers, experimental methods for the evaluation of heat exchanger performance, and thermal calculation algorithms for multi-stream heat exchangers and heat exchanger networks. - Includes MATLAB codes to illustrate how the technologies and methods discussed can be easily applied and developed - Analyses a range of different models, applications, and case studies in order to reveal more advanced solutions for industrial applications - Maintains a strong focus on the fundamental theories and principles of the heat transfer performance of heat exchangers and their applications for complex flow arrangement

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1972 with total page 810 pages. Available in PDF, EPUB and Kindle. Book excerpt: