Download or read book Modeling and Numerical Simulation of Oscillatory Two phase Flows with Application to Boiling Water Nuclear Reactors written by and published by . This book was released on 1995 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper is concerned with the analysis of dynamics and stability of boiling channels and systems. The specific objectives are two-fold. One of them is to present the results of a study aimed at analyzing the effects of various modeling concepts and numerical approaches on the transient response and stability of parallel boiling channels. The other objective is to investigate the effect of closed-loop feedback on stability of a boiling water reactor (BWR). Various modeling and computational issues for parallel boiling channels are discussed, such as: the impact of the numerical discretization scheme for the node containing the moving boiling boundary on the convergence and accuracy of computations, and the effects of subcooled boiling and other two-phase flow phenomena on the predictions of marginal stability conditions. Furthermore, the effects are analyzed of local loss coefficients around the recirculation loop of a boiling water reactor on stability of the reactor system. An apparent paradox is explained concerning the impact of changing single-phase losses on loop stability. The calculations have been performed using the DYNOBOSS computer code. The results of DYNOBOSS validation against other computer codes and experimental data are shown.
Download or read book Experimental and Numerical Stability Investigations on Natural Circulation Boiling Water Reactors written by Christian Pablo Marcel and published by IOS Press. This book was released on 2007 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the design of novel nuclear reactors active systems are replaced by passive ones in order to reduce the risk of failure. For that reason natural circulation is being considered as the primary cooling mechanism in next generation nuclear reactor designs such as the natural circulation boiling water reactor (BWR). In such a reactor, however, the flow is not a controlled parameter but is dependent on the power. As a result, the dynamical behavior significantly differs from that in conventional forced circulation BWRs. For that reason, predicting the stability characteristics of these reactors has to be carefully studied. In this work, a number of open issues are investigated regarding the stability of natural circulation BWRs (e.g. margins to instabilities at rated conditions, interaction between the thermal-hydraulics and the neutronics, and the occurrence of flashing induced instabilities) with a strong emphasis on experimental evidence.
Download or read book An Experimental and Modelling Study of Natural circulation Boiling Water Reactor Dynamics written by Róbert Zboray and published by IOS Press. This book was released on 2002 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contents of this Doctoral Dissertation include: Understanding the linear stability characteristics of BWRs, Experiments on the stability of the Desire facility, Applications of the reducer-order model, Numerical analysis of the nonlinear dynamics of BWRs, Experiments on the nonlinear dynamics of natural-circulation two-phase flows, Experiments on the neutronic-thermalhydraulic stability, Conclusions and Discussion
Download or read book Two Phase Flow Phase Change and Numerical Modeling written by Jeff Winters and published by . This book was released on 2016-10-01 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: The heat transfer and analysis on laser beam, evaporator coils, shell-and-tube condenser, two phase flow, nanofluids, complex fluids, and on phase change are significant issues in a design of wide range of industrial processes and devices. The most common class of multiphase flows are two-phase flows. A gas-liquid flow is probably the most important form of multiphase flow, and is found widely in a whole range of industrial applications. These include pipeline systems for the transport of oil-gas mixtures, evaporators, boilers, condensers, submerged combustion systems, sewerage treatment plants, air-conditioning and refrigeration plants, and cryogenic plants. Gas-liquid systems are also important in the meteorology and in other natural phenomena. Flows of solids suspended in gases are important in pneumatic conveying and in pulverized fuel combustion. Fluidized beds may also be regarded as a form of gas-solid flow. Liquid-liquid flows are the flow of oil-water mixtures in pipelines and in liquid-liquid solvent extraction mass transfer systems. The most important application of liquid-solid flow is in the hydraulic conveying of solid materials. Liquid-solid suspensions also occur in crystallization systems, and in hydro-cyclones. Historically, probably the most commonly studied cases of two-phase flow are in large-scale power systems. Coal and gas-fired power stations used very large boilers to produce steam for use in turbines.Two Phase Flow, Phase Change and Numerical Modeling covers mainly numerical modeling of heat transfer, two phase flow, nanofluids, and phase change.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1986 with total page 770 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Two Phase Flow Boiling and Condensation written by S. Mostafa Ghiaasiaan and published by Cambridge University Press. This book was released on 2007-10-22 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text is an introduction to gas-liquid two-phase flow, boiling and condensation for graduate students, professionals, and researchers in mechanical, nuclear, and chemical engineering. The book provides a balanced coverage of two-phase flow and phase change fundamentals, well-established art and science dealing with conventional systems, and the rapidly developing areas of microchannel flow and heat transfer. It is based on the author's more than 15 years of teaching experience. Instructors teaching multiphase flow have had to rely on a multitude of books and reference materials. This book remedies that problem by covering all the topics that are essential for a graduate first course. Among the important areas that are discussed in the book, and are not adequately covered by virtually all the available textbooks, are: two-phase flow model conservation equations and their numerical solution; condensation with and without noncondensables; and two-phase flow, boiling, and condensation in mini and microchannels.
Download or read book Two Phase Flow Boiling and Condensation written by S. Mostafa Ghiaasiaan and published by Cambridge University Press. This book was released on 2017-01-11 with total page 1322 pages. Available in PDF, EPUB and Kindle. Book excerpt: Providing a comprehensive introduction to the fundamentals and applications of flow and heat transfer in conventional and miniature systems, this fully enhanced and updated edition covers all the topics essential for graduate courses on two-phase flow, boiling, and condensation. Beginning with a concise review of single-phase flow fundamentals and interfacial phenomena, detailed and clear discussion is provided on a range of topics, including two-phase hydrodynamics and flow regimes, mathematical modeling of gas-liquid two-phase flows, pool and flow boiling, flow and boiling in mini and microchannels, external and internal-flow condensation with and without noncondensables, condensation in small flow passages, and two-phase choked flow. Numerous solved examples and end-of-chapter problems that include many common design problems likely to be encountered by students, make this an essential text for graduate students. With up-to-date detail on the most recent research trends and practical applications, it is also an ideal reference for professionals and researchers in mechanical, nuclear, and chemical engineering.
Download or read book Two phase Flows and Heat Transfer with Application to Nuclear Reactor Design Problems written by Jean J. Ginoux and published by Hemisphere Pub. This book was released on 1978 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computer Simulation of Two phase Flow in Nuclear Reactors written by and published by . This book was released on 1992 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-phase flow models dominate the economic resource requirements for development and use of computer codes for analyzing thermohydraulic transients in nuclear power plants. Six principles are presented on mathematical modeling and selection of numerical methods, along with suggestions on programming and machine selection, all aimed at reducing the cost of analysis. Computer simulation is contrasted with traditional computer calculation. The advantages of run-time interactive access operation in a simulation environment are demonstrated. It is explained that the drift-flux model is better suited for two-phase flow analysis in nuclear reactors than the two-fluid model, because of the latter's closure problem. The advantage of analytical over numerical integration is demonstrated. Modeling and programming techniques are presented which minimize the number of needed arithmetical and logical operations and thereby increase the simulation speed, while decreasing the cost.
Download or read book Two Phase Flow written by Cl Kleinstreuer and published by CRC Press. This book was released on 2003-05-23 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: This graduate text provides a unified treatment of the fundamental principles of two-phase flow and shows how to apply the principles to a variety of homogeneous mixture as well as separated liquid-liquid, gas-solid, liquid-solid, and gas-liquid flow problems, which may be steady or transient, laminar or turbulent. Each chapter contains several sample problems, which illustrate the outlined theory and provide approaches to find simplified analytic descriptions of complex two-phase flow phenomena. This well-balanced introductory text will be suitable for advanced seniors and graduate students in mechanical, chemical, biomedical, nuclear, environmental and aerospace engineering, as well as in applied mathematics and the physical sciences. It will be a valuable reference for practicing engineers and scientists. A solutions manual is available to qualified instructors.
Download or read book A New Method for Determining the Stability of Two phase Flow in Parallel Heated Channels with Applications to Nuclear Reactors written by J. H. Bick and published by . This book was released on 1960 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental and Theoretical Study of Oscillatory Two Phase Flows with Heat and Mass Transfer written by Faith Rose Beck and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents experimental and theoretical analyses of oscillatory two-phase flows with heat and mass transfer on liquid carryover behavior during refloodof a simulated nuclear reactor core. In a hypothetical large break loss of coolantaccident (LBLOCA), associated with a break in one of the hot- or cold-legs, theemergency core cooling system (ECCS) must provide sufficient coolant to the coreto remove decay heat and prevent the cladding from exceeding 1477.6 K. Duringreflood, flow to the core is gravity-driven, resulting in an oscillatory delivery ofcoolant. These oscillations have been attributed to vapor generation in the coreand a dynamic response of the downcomer water level. Nearly all reflood simulation experiments have been conducted with constant reflood rates, and have not considered the effect of oscillations on rod bundle thermal-hydraulics. The few studies that have been conducted with oscillating flow indicated enhanced entrainment and carryover of liquid from the quench front. While higher entrainmentcan provide precursory cooling ahead of the quench front, it can also expel morecoolant out of the system during oscillatory reflood. The amount of liquid entrained can be significant because, in an accident scenario, the quench rate will beslowed, and it can take longer to fully recover the core. At the Nuclear Regulatory Commission (NRC)/Penn State University (PSU) Rod Bundle Heat Transfer(RBHT) Test Facility, an electrically heated 77, 3.66 m (full-length) rod bundlearray has the capability of performing both constant and oscillatory forced floodingrate experiments. The facility is heavily instrumented, equipped with seven spacergrids with which to analyze droplet and heat transfer phenomena. The system canvary the oscillation period (2 to 10 s), magnitude (0.0254 to 0.0762 m/s), systempressure (0.14 to 0.41 MPa), and subcooling (5 to 55 C) in order to study theentrained droplet dynamics and heat transfer under constant and oscillatory flowconditions.This dissertation includes the analysis of forced oscillatory reflood experiments, which concentrate on the effects of flow (frequency, magnitude, and nominal flooding rate) and system parameters (pressure, subcooling, and bundle fouling) on heat transfer and entrained droplet dynamics. Major findings from the experimental work include: 1) decreasing the oscillation period decreases the peak cladding temperature and the steam temperatures, as well as enhances the liquid carryoverwhen compared with constant reflood experiments; 2) decreasing the system pres-sure enhances the effect of flow oscillations; and 3) the presence of bundle foulingimproves cooling and decreases the amount of liquid carryover. To the authorsknowledge, experiments with the parameters varied in this work, coupled with therod bundle geometry, have not been explored previously.This dissertation utilizes the unique dataset collected at the NRC/PSU RBHT to perform a stability analysis of oscillatory two-phase flows. The governing equations established for this flow incorporate Floquet and viscous-potential flow theories. From the analysis, it is found that the stability at the two-phase interface is highly dependent on the flow orientation and heat transfer to the system. Inaddition, a correlation is developed for the liquid carryover that uses parameters derived from the stability analysis to predict the carryover during oscillatory reflood. The correlation is the first of its kind to include the effects of a moving quench front on the liquid carryover. The carryover model is validated using NRC/PSU RBHT data, as well as other relevant rod bundle data, and the NRCs TRACE code.
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1976 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ERDA Energy Research Abstracts written by United States. Energy Research and Development Administration and published by . This book was released on 1977 with total page 1080 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ERDA Energy Research Abstracts written by United States. Energy Research and Development Administration. Technical Information Center and published by . This book was released on 1977 with total page 1682 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Numerical Simulation of Boiling Multiphase Flows written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The state-of-the-art for Direct Numerical Simulation (DNS) of boiling multiphase flows is reviewed, focussing on potential of available computational techniques, the level of current success for their applications to model several basic flow regimes (film, pool-nucleate and wall-nucleate boiling -- FB, PNB and WNB, respectively). Then, we discuss multiphysics and multiscale nature of practical boiling flows in LWR reactors, requiring high-fidelity treatment of interfacial dynamics, phase-change, hydrodynamics, compressibility, heat transfer, and non-equilibrium thermodynamics and chemistry of liquid/vapor and fluid/solid-wall interfaces. Finally, we outline the framework for the {\sf Fervent} code, being developed at INL for DNS of reactor-relevant boiling multiphase flows, with the purpose of gaining insight into the physics of multiphase flow regimes, and generating a basis for effective-field modeling in terms of its formulation and closure laws.
