The ability to predict gas-liquid flow patterns is crucial to the design and operation of two-phase flow systems in the microgravity environment. Flow pattern maps have been developed in this study which show the occurrence of flow patterns as a function of gas and liquid superficial velocities as well as tube diameter, liquid viscosity and surface tension. The results have demonstrated that the location of the bubble-slug transition is affected by the tube diameter for air-water systems and by surface tension, suggesting that turbulence-induced bubble fluctuations and coalescence mechanisms play a role in this transition. The location of the slug-annular transition on the flow pattern maps is largely unaffected by tube diameter, liquid viscosity or surface tension in the ranges tested. Void fraction-based transition criteria were developed which separate the flow patterns on the flow pattern maps with reasonable accuracy. Weber number transition criteria also show promise but further work is needed to improve these models. For annular gas-liquid flows of air-water and air- 50 percent glycerine under reduced gravity conditions, the pressure gradient agrees fairly well with a version of the Lockhart-Martinelli correlation but the measured film thickness deviates from published correlations at lower Reynolds numbers. Nusselt numbers, based on a film thickness obtained from standard normal-gravity correlations, follow the relation, Nu = A Re(sup n) Pr(exp l/3), but more experimental data in a reduced gravity environment are needed to increase the confidence in the estimated constants, A and n. In the slug flow regime, experimental pressure gradient does not correlate well with either the Lockhart-Martinelli or a homogeneous formulation, but does correlate nicely with a formulation based on a two-phase Reynolds number. Comparison with ground-based correlations implies that the heat transfer coefficients are lower at reduced gravity than at normal gravity under the same ...

Multiphase thermal systems have numerous applications in aerospace, heat-exchange, transport of contaminants in environmental systems, and energy transport and conversion systems. A reduced - or microgravity - environment provides an excellent tool for accurate study of the flow without the masking effects of gravity. This book presents for the first time a comprehensive coverage of all aspects of two-phase flow behaviour in the virtual absence of gravity.

This book presents the fundamentals of low gravity fluid dynamics and heat transfer. It investigates fluid behavior in low gravity environments such as those found in earth orbiting and space vehicles. The two major fluid phenomena affected by gravity (buoyancy and surface tension) are treated thoroughly from both the theoretical and applications points of view, and limitations of fluid and thermal responses to gravitational fields in space-based settings are clearly delineated. Summaries of all data available from low gravity flight and terrestrial experiments performed to date are also presented.

In a microgravity experiment, the conditions prevalent in fluid phases can be substantially different from those on the ground and can be exploited to improve different processes. Fluid physics research in microgravity is important for the advancement of all microgravity scients: life, material, and engineering. Space flight provides a unique laboratory that allows scientists to improve their understanding of the behaviour of fluids in low gravity, allowing the investigation of phenomena and processes normally masked by the effects of gravity and thus difficult to study on Earth. Physics of Fluids in Microgravity provides a clear view of recent research and progress in the different fields of fluid research in space. The topics presented include bubles and drops dynamics, Maragoni flows, diffustion and thermodiffusion, solidfication,a nd crystal growth. The results obtained so far are, in some cases, to be confirmed by extensive research activities on the International Space station, where basic and applied microgravity experimentation will take place in the years to come.

A guide to two-phase heat transfer theory, practice, and applications Designed primarily as a practical resource for design and development engineers, Two-Phase Heat Transfer contains the theories and methods of two-phase heat transfer that are solution oriented. Written in a clear and concise manner, the book includes information on physical phenomena, experimental data, theoretical solutions, and empirical correlations. A very wide range of real-world applications and formulas/correlations for them are presented. The two-phase heat transfer systems covered in the book include boiling, condensation, gas-liquid mixtures, and gas-solid mixtures. The author—a noted expert in this field—also reviews the numerous applications of two-phase heat transfer such as heat exchangers in refrigeration and air conditioning, conventional and nuclear power generation, solar power plants, aeronautics, chemical processes, petroleum industry, and more. Special attention is given to heat exchangers using mini-channels which are being increasingly used in a variety of applications. This important book: Offers a practical guide to two-phase heat transfer Includes clear guidance for design professionals by identifying the best available predictive techniques Reviews the extensive literature on heat transfer in two-phase systems Presents information to aid in the design and analysis of heat exchangers. Written for students and research, design, and development engineers, Two-Phase Heat Transfer is a comprehensive volume that covers the theory, methods, and applications of two-phase heat transfer.

"Multiphase flow and heat transfer have found a wide range of applications in several engineering and science fields such as mechanical engineering, chemical and petrochemical engineering, nuclear engineering, energy engineering, material engineering, ocea"