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 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 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 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 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 Energy Research Abstracts written by and published by . This book was released on 1985 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Laminar Flow Forced Convection in Ducts written by R. K. Shah and published by Academic Press. This book was released on 2014-06-28 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laminar Flow Forced Convection in Ducts is a sourcebook for compact heat exchanger analytical data. This book describes the analytical solutions for laminar fluid flow and forced convection heat transfer in circular and noncircular pipes, including applicable differential equations and boundary conditions involving velocity and temperature problems of fluid flow. The book also discusses fluid flow—how much power is required to pump fluids through the heat exchanger, as well as the heat transfer—the determination of q" distribution, and the temperature of fluid and walls. The text also analyzes the coolant or heat transfer fluid flows in a nuclear power reactor composed of a bundle of circular section fuel rods located inside a round tube. R.A. Axford addresses fluid flow and heat transfers results for the rod bundle geometry in "Heat Transfer in Rod Bundles." The book also provides an overview and guidelines that can be used for the designer and the applied mathematician. This book is suitable for engineers working in electronics, aerospace, instrumentation, and biomechanics that use cooling or heating exchanges or solar collection systems.
Download or read book Physics Briefs written by and published by . This book was released on 1984 with total page 986 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Introduction to Convective Heat Transfer Analysis written by P. H. Oosthuizen and published by McGraw-Hill Science, Engineering & Mathematics. This book was released on 1999 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt: A student-oriented approach in which basic ideas and assumptions are stressed and discussed in detail and full developments of all important analyses are provided. The book contains many worked examples that illustrate the methods of analysis discussed. The book also contains a comprehensive set of problems and a Solutions Manual, written by the text authors.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1998 with total page 920 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamentals of Multiphase Flow written by Christopher E. Brennen and published by Cambridge University Press. This book was released on 2005-04-18 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: Publisher Description
Download or read book Analytical Heat Transfer written by Je-Chin Han and published by CRC Press. This book was released on 2022-06-24 with total page 595 pages. Available in PDF, EPUB and Kindle. Book excerpt: Analytical Heat Transfer explains how to analyze and solve conduction, convection, and radiation heat transfer problems. It enables students to tackle complex engineering heat transfer problems prevalent in practice. Covering heat transfer in high-speed flows and unsteady highly turbulent flows, the book also discusses enhanced heat transfer in channels, heat transfer in rotating channels, numerical modeling for turbulent flow heat transfer, and thermally developing heat transfer in a circular tube. The second edition features new content on Duhamel’s superposition method, Green’s function method for transient heat conduction, finite-difference method for steady state and transient heat conduction in cylindrical coordinates, and laminar mixed convection. It includes two new chapters on laminar-to-turbulent transitional heat transfer and turbulent flow heat transfer enhancement, in addition to end-of-chapter problems. The book bridges the gap between basic heat transfer undergraduate courses and advanced heat transfer graduate courses for a single semester of intermediate heat transfer, advanced conduction/radiation heat transfer, or convection heat transfer. Features: Focuses on analyzing and solving classic heat transfer problems in conduction, convection, and radiation Covers 2-D and 3-D view factor evaluation, combined radiation with conduction and/or convection, and gas radiation optically thin and optically thick limits Features updated content and new chapters on mass and heat transfer analogy, thermally developing heat transfer in a circular tube, laminar-turbulent transitional heat transfer, unsteady highly turbulent flows, enhanced heat transfer in channels, heat transfer in rotating channels, and numerical modeling for turbulent flow heat transfer Provides step-by-step mathematical formula derivations, analytical solution procedures, and demonstration examples Includes end-of-chapter problems with an accompanying Solutions Manual for instructors This book is ideal for undergraduate and graduate students studying basic heat transfer and advanced heat transfer.
Download or read book Principles of Environmental Physics written by John Monteith and published by Butterworth-Heinemann. This book was released on 1990-02-15 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thoroughly revised and up-dated edition of a highly successful textbook.
Download or read book Boundary Layer Theory written by Hermann Schlichting (Deceased) and published by Springer. This book was released on 2016-10-04 with total page 814 pages. Available in PDF, EPUB and Kindle. Book excerpt: This new edition of the near-legendary textbook by Schlichting and revised by Gersten presents a comprehensive overview of boundary-layer theory and its application to all areas of fluid mechanics, with particular emphasis on the flow past bodies (e.g. aircraft aerodynamics). The new edition features an updated reference list and over 100 additional changes throughout the book, reflecting the latest advances on the subject.
Download or read book INIS Atomindex written by and published by . This book was released on 1983 with total page 900 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 1989 with total page 744 pages. Available in PDF, EPUB and Kindle. Book excerpt:
