Bubble Dynamics And Heat Transfer In Pool Boiling On Wires At Different Gravity
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Bubble Dynamics And Heat Transfer In Pool Boiling On Wires At Different Gravity
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Author : Jian-Fu Zhao
language : en
Publisher:
Release Date : 2011
Bubble Dynamics And Heat Transfer In Pool Boiling On Wires At Different Gravity written by Jian-Fu Zhao and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Biotechnology categories.
A series of experimental studies on bubble dynamical behaviors and heat transfer in pool boiling on thin wires in different gravity conditions have been performed in the past years, including experiments in long-term microgravity aboard the 22nd Chinese recoverable satellite RS-22, in short-term microgravity in the drop tower Beijing, and in normal gravity on the ground. Steady pool boiling of degassed R113 on thin platinum wires has been studied using a temperature-controlled heating method. A voltage-controlled heating method has also been used in normal gravity. A slight enhancement of nucleate boiling heat transfer is observed in microgravity, while dramatic changes of bubble behaviors are very evident. Considering the influence of the Marangoni effects, the different characteristics of bubble behaviors in microgravity have been explained. A new bubble departure model including the influence of the Marangoni effects has also been proposed, which can predict the whole observation both in microgravity and in normal gravity. The value of CHF (critical heat flux) in microgravity is lower than that in normal gravity, but it can be predicted well by the Lienhard-Dhir correlation, although the dimensionless radius, or the square root of the Bond number, in the present case is far beyond its initial application range. A further revisit on the scaling of CHF with heater radius in normal gravity, which is focused on the case of a small Bond number, has also been performed in our laboratory using different kinds of working fluids at different subcooling conditions. Interactions between the influences of the subcooling and heater radius will be important for the case of a small Bond number. In addition to the Bond number, there may exist some other parameters, which may be material-dependent, that play important roles in the CHF phenomenon with a small Bond number.
Bubble Dynamics Two Phase Flow And Boiling Heat Transfer In Microgravity
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Author : National Aeronautics and Space Administration (NASA)
language : en
Publisher: Createspace Independent Publishing Platform
Release Date : 2018-07-23
Bubble Dynamics Two Phase Flow And Boiling Heat Transfer In Microgravity written by National Aeronautics and Space Administration (NASA) and has been published by Createspace Independent Publishing Platform this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-07-23 with categories.
This report contains two independent sections. Part one is titled Terrestrial and Microgravity Pool Boiling Heat Transfer and Critical heat flux phenomenon in an acoustic standing wave. Terrestrial and microgravity pool boiling heat transfer experiments were performed in the presence of a standing acoustic wave from a platinum wire resistance heater using degassed FC-72 Fluorinert liquid. The sound wave was created by driving a half wavelength resonator at a frequency of 10.15 kHz. Microgravity conditions were created using the 2.1 second drop tower on the campus of Washington State University. Burnout of the heater wire, often encountered with heat flux controlled systems, was avoided by using a constant temperature controller to regulate the heater wire temperature. The amplitude of the acoustic standing wave was increased from 28 kPa to over 70 kPa and these pressure measurements were made using a hydrophone fabricated with a small piezoelectric ceramic. Cavitation incurred during experiments at higher acoustic amplitudes contributed to the vapor bubble dynamics and heat transfer. The heater wire was positioned at three different locations within the acoustic field: the acoustic node, antinode, and halfway between these locations. Complete boiling curves are presented to show how the applied acoustic field enhanced boiling heat transfer and increased critical heat flux in microgravity and terrestrial environments. Video images provide information on the interaction between the vapor bubbles and the acoustic field. Part two is titled, Design and qualification of a microscale heater array for use in boiling heat transfer. This part is summarized herein. Boiling heat transfer is an efficient means of heat transfer because a large amount of heat can be removed from a surface using a relatively small temperature difference between the surface and the bulk liquid. However, the mechanisms that govern boiling heat transfer are not well understood. Measurements of wall te...
Numerical Simulations Of Bubble Dynamics And Heat Transfer In Pool Building
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Author : Eduardo Aktinol
language : en
Publisher:
Release Date : 2014
Numerical Simulations Of Bubble Dynamics And Heat Transfer In Pool Building written by Eduardo Aktinol and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Due to the complex nature of the subprocesses involved in nucleate boiling, it has not been possible to develop comprehensive models or correlations despite decades of accumulated data and analysis. Complications such as the presence of dissolved gas in the liquid further confound attempts at modeling nucleate boiling. Moreover, existing empirical correlations may not be suitable for new applications, especially with regards to varying gravity level. More recently, numerical simulations of the boiling process have proven to be capable of reliably predicting bubble dynamics and associated heat transfer by showing excellent agreement with experimental data. However, most simulations decouple the solid substrate by assuming constant wall temperature. In the present study complete numerical simulations of the boiling process are performed--including conjugate transient conduction in the solid substrate and the effects of dissolved gas in the liquid at different levels of gravity. Finite difference schemes are used to discretize the governing equations in the liquid, vapor, and solid phases. The interface between liquid and vapor phases is tracked by a level set method. An iterative procedure is used at the interface between the solid and fluid phases. Near the three-phase contact line, temperatures in the solid are observed to fluctuate significantly over short periods. The results show good agreement with the data available in the literature. The results also show that waiting and growth periods can be related directly to wall superheat. The functional relationship between waiting period and wall superheat is found to agree well with empirical correlations reported in the literature. For the case of a single bubble in subcooled nucleate boiling, the presence of dissolved gas in the liquid is found to cause noncondensables to accumulate at the top of the bubble where most condensation occurs. This results in reduced local saturation temperature and condensation rates. The numerical predictions show reasonable agreement with the results from experiments performed at microgravity. For nucleate boiling at microgravity the simulations predict a drastic change in vapor removal pattern when compared to Earth normal gravity. The predictions match well with experimental results. However, simulated heat transfer rates were significantly under-predicted.
Experimental Investigation Of Nucleate Boiling Bubble Dynamics In Normal And Zero Gravities
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Author : Thomas H. Cochran
language : en
Publisher:
Release Date : 1968
Experimental Investigation Of Nucleate Boiling Bubble Dynamics In Normal And Zero Gravities written by Thomas H. Cochran and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1968 with Bubbles categories.
Effects Of Fluid Properties And Gravity Level On Boiling In The Discrete Bubble Region
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Author : Thomas H. Cochran
language : en
Publisher:
Release Date : 1967
Effects Of Fluid Properties And Gravity Level On Boiling In The Discrete Bubble Region written by Thomas H. Cochran and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1967 with Fluid dynamics (Space environment) categories.
Heat Transfer
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Author : Aziz Belmiloudi
language : en
Publisher: BoD – Books on Demand
Release Date : 2011-01-28
Heat Transfer written by Aziz Belmiloudi and has been published by BoD – Books on Demand this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-01-28 with Science categories.
Over the past few decades there has been a prolific increase in research and development in area of heat transfer, heat exchangers and their associated technologies. This book is a collection of current research in the above mentioned areas and discusses experimental, theoretical and calculation approaches and industrial utilizations with modern ideas and methods to study heat transfer for single and multiphase systems. The topics considered include various basic concepts of heat transfer, the fundamental modes of heat transfer (namely conduction, convection and radiation), thermophysical properties, condensation, boiling, freezing, innovative experiments, measurement analysis, theoretical models and simulations, with many real-world problems and important modern applications. The book is divided in four sections : "Heat Transfer in Micro Systems", "Boiling, Freezing and Condensation Heat Transfer", "Heat Transfer and its Assessment", "Heat Transfer Calculations", and each section discusses a wide variety of techniques, methods and applications in accordance with the subjects. The combination of theoretical and experimental investigations with many important practical applications of current interest will make this book of interest to researchers, scientists, engineers and graduate students, who make use of experimental and theoretical investigations, assessment and enhancement techniques in this multidisciplinary field as well as to researchers in mathematical modelling, computer simulations and information sciences, who make use of experimental and theoretical investigations as a means of critical assessment of models and results derived from advanced numerical simulations and improvement of the developed models and numerical methods.
Advances In Heat Transfer
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Author :
language : en
Publisher: Academic Press
Release Date : 2015-10-27
Advances In Heat Transfer written by and has been published by Academic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-10-27 with Science categories.
Advances in Heat Transfer 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. The articles, which serve as a broad review for experts in the field are also of great interest to non-specialists who need to keep up-to-date with the results of the latest research. This serial is essential reading for all mechanical, chemical, and industrial engineers working in the field of heat transfer, or in graduate schools or industry. Compiles the expert opinions of leaders in the industry 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 Essential reading for all mechanical, chemical, and industrial engineers working in the field of heat transfer, or in graduate schools or industry
Physical Science Under Microgravity Experiments On Board The Sj 10 Recoverable Satellite
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Author : Wenrui Hu
language : en
Publisher: Springer Nature
Release Date : 2019-10-16
Physical Science Under Microgravity Experiments On Board The Sj 10 Recoverable Satellite written by Wenrui Hu and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-10-16 with Science categories.
This book presents the physical science experiments in a space microgravity environment conducted on board the SJ-10 recoverable satellite, which was launched on April 6th, 2016 and recovered on April 18th, 2016. The experiments described were selected from ~100 proposals from various institutions in China and around the world, and have never previously been conducted in the respective fields. They involve fluid physics and materials science, and primarily investigate the kinetic properties of matter in a space microgravity environment. The book provides a comprehensive review of these experiments, as well as the mission’s execution, data collection, and scientific outcomes.
Low Gravity Fluid Dynamics And Transport Phenomena
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Author : Robert L. Sani
language : en
Publisher: AIAA
Release Date : 1990
Low Gravity Fluid Dynamics And Transport Phenomena written by Robert L. Sani and has been published by AIAA this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with Capillarity categories.
Effects Of Subcooling And Gravity Level On Boiling In The Discrete Bubble Region
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Author : Thomas H. Cochran
language : en
Publisher:
Release Date : 1966
Effects Of Subcooling And Gravity Level On Boiling In The Discrete Bubble Region written by Thomas H. Cochran and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1966 with Bubbles categories.