Download or read book The Influence of a Multiple Tube Inlet Condition on Heat Transfer in the Transitional Flow Regime written by Leslie Matthew James Pallent and published by . This book was released on 2017 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the industrial design of heat exchangers, engineers have long followed the general rule of avoiding transitional flow, and have rather designed a system operating in the turbulent flow regime. Whilst the turbulent regime is better for heat transfer, the higher friction inside the tube results in a much higher pressure drop which inevitably results in the system requiring a more powerful pump than if the system were to operate in the laminar regime. Designing a heat exchanger that operates in the turbulent flow regime is often the safer option, since little published design data is available for flow in the transitional flow regime, giving rise to numerous unwanted uncertainties during the design phase. Recent research into the transitional flow regime has resulted in promising experimental data that shows the regime is not as unstable as previously suspected. The regime allows for higher heat transfer than flows in the laminar regime, yet lower pressure drops than flows in the turbulent regime. Numerous investigations have previously been performed on a single uniformly heated tube operating in the transitional flow regime, however, there exists no data on the influence of a multiple tube inlet condition, as typically found in shell and tube heat exchangers, on the heat transfer characteristics. The purpose of this study was thus to determine the influence of varying tube pitch ratios on the fully developed heat transfer characteristics of three smooth circular horizontal tubes. An experimental set up was designed and built to accommodate a single tube heat exchanger used for validation purposes, and a multiple tube heat exchanger comprising of three identical and equally spaced tubes. Using a DC power supply, the tubes were uniformly heated at 2, 3 and 4 kW/m2 along the length of the test section. The heat transfer characteristics were determined experimentally for outer diameter tube pitch ratios of 1.25 and 1.5 of three 4 mm inner diameter tubes, each 6 m in length for a range of Reynolds numbers of 1 000 to 7 000. Water was used as the test fluid. Using PT100 probes and thermocouples at the inlet, outlet and outer surface of the test section, it was found that the presence of multiple tubes at the inlet of the heat exchanger for a pitch ratio of 1.25 promoted the onset of transition for the centre tube, and sharpened the transition gradient of the outer tubes. This effect noticeably increased with increasing heat flux and was absent at the higher pitch ratio of 1.5.
Download or read book The Influence of a Multiple Tube Inlet Condition on Fully developed Friction Factors in the Transitional Flow Regime written by Martin Joubert and published by . This book was released on 2017 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1975 with total page 1070 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Inlet Effects of Multiple Tubes on the Adiabatic Pressure Drop of Smooth Horizontal Tubes in the Transitional Flow Regime written by Erin Sarah Vause and published by . This book was released on 2015 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Heat Transfer and Thermal Engineering written by Chuang Wen and published by Springer Nature. This book was released on 2021-06-01 with total page 914 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers selected papers from the 16th UK Heat Transfer Conference (UKHTC2019), which is organised every two years under the aegis of the UK National Heat Transfer Committee. It is the premier forum in the UK for the local and international heat transfer community to meet, disseminate ongoing work, and discuss the latest advances in the heat transfer field. Given the range of topics discussed, these proceedings offer a valuable asset for engineering researchers and postgraduate students alike.
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 Encyclopedia Of Two phase Heat Transfer And Flow Ii Special Topics And Applications A 4 volume Set written by John R Thome and published by World Scientific. This book was released on 2015-08-26 with total page 1321 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of the two-set series is to present a very detailed and up-to-date reference for researchers and practicing engineers in the fields of mechanical, refrigeration, chemical, nuclear and electronics engineering on the important topic of two-phase heat transfer and two-phase flow. The scope of the first set of 4 volumes presents the fundamentals of the two-phase flows and heat transfer mechanisms, and describes in detail the most important prediction methods, while the scope of the second set of 4 volumes presents numerous special topics and numerous applications, also including numerical simulation methods.Practicing engineers will find extensive coverage to applications involving: multi-microchannel evaporator cold plates for electronics cooling, boiling on enhanced tubes and tube bundles, flow pattern based methods for predicting boiling and condensation inside horizontal tubes, pressure drop methods for singularies (U-bends and contractions), boiling in multiport tubes, and boiling and condensation in plate heat exchangers. All of these chapters include the latest methods for predicting not only local heat transfer coefficients but also pressure drops.Professors and students will find this 'Encyclopedia of Two-Phase Heat Transfer and Flow' particularly exciting, as it contains authored books and thorough state-of-the-art reviews on many basic and special topics, such as numerical modeling of two-phase heat transfer and adiabatic bubbly and slug flows, the unified annular flow boiling model, flow pattern maps, condensation and boiling theories, new emerging topics, etc.
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 Heat Transfer and Pressure Drop in Annuli with Non uniform Internal Wall Temperatures in the Transition Flow Regime written by Dickson Daniel Ndenguma and published by . This book was released on 2017 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is common practice to design heat exchangers that are operated in either the laminar or the turbulent flow regime and not in the transition flow regime. This could mainly be due to a lack of knowledge on the behaviour in the transition flow regime for several reasons. However, due to factors such as design constraints, heat exchangers may indeed operate in the transition flow regime. An experimental study was conducted to determine the lower and upper Reynolds number limits of the transition flow regime, and the characteristics of the heat transfer coefficients and friction factors for annular passages with different geometric dimensions. The inner wall of the annular passage had different degrees of non-uniform temperature, while the outer wall was insulated. Both heated and cooled flow applications with water as fluid (cold fluid and hot fluid respectively) were investigated. The isothermal condition investigation was also conducted for pressure drop. Four horizontal concentric counter-flow tube-in-tube heat exchangers with conventional inlet geometries were considered to obtain the required data. The hydraulic diameters of the test sections were 26.2 mm, 23 mm, 20.2 mm and 17 mm, their respective annular diameter ratios were 0.327, 0.409, 0.386 and 0.483 and their length-to-hydraulic ratios were 193, 221, 251 and 299 respectively. The flow was both hydrodynamic and thermally developing. Test data of laminar, transition and turbulent flow regimes was collected. However, the transition flow regime was the main area of interest for this study. The transition flow regime was found to exhibit either mixed or forced convection types. Average heat transfer coefficients were obtained for both heating and cooling cases, while friction factors were obtained for heating, cooling and isothermal conditions. Uncertainties in the friction factor and Nusselt number were on average below 5.6% and 10.5%, respectively. The geometric size of the annular passage, degree of wall temperature uniformity and direction of the heat flux (heating and cooling cases of annular fluid) had a significant influence on the heat transfer coefficients, friction factors and Reynolds number span of the transition flow regime. New correlations for predicting the transition flow regime Reynolds number spans, Nusselt numbers and friction factors were developed for the transition flow regime and predicted most of the data to within +-10%.
Download or read book Encyclopedia Of Two phase Heat Transfer And Flow I Fundamentals And Methods A 4 volume Set written by John R Thome and published by World Scientific. This book was released on 2015-08-14 with total page 1109 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of the two-set series is to present a very detailed and up-to-date reference for researchers and practicing engineers in the fields of mechanical, refrigeration, chemical, nuclear and electronics engineering on the important topic of two-phase heat transfer and two-phase flow. The scope of the first set of 4 volumes presents the fundamentals of the two-phase flows and heat transfer mechanisms, and describes in detail the most important prediction methods, while the scope of the second set of 4 volumes presents numerous special topics and numerous applications, also including numerical simulation methods.Practicing engineers will find extensive coverage to applications involving: multi-microchannel evaporator cold plates for electronics cooling, boiling on enhanced tubes and tube bundles, flow pattern based methods for predicting boiling and condensation inside horizontal tubes, pressure drop methods for singularies (U-bends and contractions), boiling in multiport tubes, and boiling and condensation in plate heat exchangers. All of these chapters include the latest methods for predicting not only local heat transfer coefficients but also pressure drops.Professors and students will find this 'Encyclopediaa of Two-Phase Heat Transfer and Flow' particularly exciting, as it contains authored books and thorough state-of-the-art reviews on many basic and special topics, such as numerical modeling of two-phase heat tranfser and adiabatic bubbly and slug flows, the unified annular flow boiling model, flow pattern maps, condensation and boiling theories, new emerging topics, etc.
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 General Papers in Heat Transfer written by M. K. Jensen and published by . This book was released on 1992 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1993 with total page 354 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 1971 with total page 804 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transient Non equilibrium Two phase Flow written by Yat-Sun Ng and published by . This book was released on 1986 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the ASME Heat Transfer Division written by and published by . This book was released on 1997 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt:
