Download or read book Measurement Analysis and Modeling of Non Isothermal Low Velocity Displacement Ventilation Jets written by Laurent Magnier-Bergeron and published by . This book was released on 2016 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: Displacement Ventilation (DV) is an air distribution method recognized to enhance indoor air quality, while having a great potential for energy savings, due to stratification, higher supply air temperature and opportunity of free cooling. A frequent complaint associated with displacement ventilation is however the draft discomfort caused by the colder air movement at foot level, and the local discomfort due to an excessive temperature difference between head and ankle. Insufficient information is currently available regarding the variations of temperature and velocity inside a DV jet. Correlation models also need to be developed to report the variation of air speed in the jet. In this thesis, the DV jet is analyzed in depth through, first, experimental measurements and, then, the development of correlation models. Measurements are performed in an environmental chamber to study the DV jet coming from two different wall-mounted DV diffusers, for different supply conditions. The variations of air speed and temperature in the longitudinal, transversal, and horizontal planes are measured and analyzed. The thermal characteristics are discussed in terms of local thermal comfort. In the second part of the thesis, the experimental data are analyzed towards developing new models for the distribution of air speed and temperature in the air jets. A new mathematical model is proposed for the variation of air speed in the secondary zone of the jet, as well as a new model is suggested for the vertical air speed profile. The variation of the thickness of the DV jet is also studied. A new mathematical is model is proposed to account for the variation of minimal air temperature in the jet. The variations of air speed and temperature in the transversal direction are also discussed. Finally, the contributions are summarized and future work is proposed.

Download or read book A Ventilation Strategy Based on Confluent Jets written by Setareh Janbakhsh and published by Linköping University Electronic Press. This book was released on 2015-04-27 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study presents air distribution systems that are based on confluent jets; this system can be of interest for the establishment of indoor environments, to fulfill the goals of indoor climate and energy-efficient usage. The main objective of this study is to provide deeper understanding of the flow field development of a supply device that is designed based on wall confluent jets and to investigate the ventilation performance by experimental and numerical methods. In this study, the supply device can be described as an array of round jets on a flat surface attached to a side wall. Multiple round jets that issue from supply device apertures are combined at a certain distance downstream from the device and behave as a united jet or so-called confluent jets. Multiple round jets that are generated from the supply device move downward and are attached to the wall at the primary region, due to the Coanda effect, and then they become wall confluent jets until the floor wall is reached. A wall jet in a secondary region is formed along the floor after the stagnation region. The characteristics of the flow field and the ventilation performance of conventional wall confluent jets and modified wall confluent jets supply devices are investigated experimentally in an office test room. The study of the modified wall confluent jets is intended to improve the efficiency of the conventional one while maintaining acceptable thermal comfort in an office environment. The results show that the modified wall confluent jets supply device can provide acceptable thermal comfort for the occupant with lower airflow rate compared to the conventional wall confluent jets supply device. Numerical predictions using three turbulence models (renormalization group (RNG k– ?), realizable (Re k– ?), and shear stress transport (SST k– ?) are evaluated by measurement results. The computational box and nozzle plate models are used to model the inlet boundary conditions of the nozzle device. In the isothermal study, the wall confluent jets in the primary region and the wall jet in the secondary region, when predicted by the three turbulence models, are in good agreement with the measurements. The non-isothermal validation studies show that the SST k– ? model is slightly better at predicting the wall confluent jets than the other two models. The SST k– ? model is used to investigate the effects of the nozzle diameter, number of nozzles, nozzle array configuration, and inlet discharge height on the ventilation performance of the proposed wall confluent jets supply device. The nozzle diameter and number of nozzles play important roles in determining the airflow pattern, temperature field, and draught distribution. Increased temperature stratification and less draught distribution are achieved by increasing the nozzle diameter and number of nozzles. The supply device with smaller nozzle diameters and fewer nozzles yields rather uniform temperature distribution due to the dominant effect of mixing. The flow behavior is nearly independent of the inlet discharge height for the studied range. The proposed wall confluent jets supply device is compared with a mixing supply device, impinging supply device and displacement supply device. The results show that the proposed wall confluent jets supply device has the combined behavior of both mixing and stratification principles. The proposed wall confluent jets supply device provides better overall ventilation performance than the mixing and displacement supply devices used in this study. This study covers also another application of confluent jets that is based on impinging technology. The supply device under consideration has an array of round jets on a curve. Multiple jets issue from the supply device aperture, in which the supply device is positioned vertically and the jets are directed against a target wall. The flow behavior and ventilation performance of the impinging confluent jets supply device is studied experimentally in an industrial premise. The results show that the impinging confluent jets supply device maintains acceptable thermal comfort in the occupied zone by creating well-distributed airflow during cold and hot seasons.

Download or read book Air Distribution in Rooms written by H.B. Awbi and published by Elsevier. This book was released on 2000 with total page 746 pages. Available in PDF, EPUB and Kindle. Book excerpt: The air distribution in occupied spaces is a major issue of public concern. It is widely recognized that the quality of air and the nature of airflow can affect the health of occupants and the energy consumed in buildings and transport vehicles. ROOMVENT is the principal international conference in the field of air distribution. It was first initiated in 1987 by SCANVAC, the Scandinavian Federation of Heating, Ventilating and Sanitary Engineering Associations in Denmark, Finland, Iceland, Norway and Sweden. The aim of the Conference is to bring together researchers from universities and research institutes, engineers from industry and government officials and policy makers, with the goal of experiencing the latest techniques for measuring and analyzing indoor air flow, the visualization of indoor air flow patterns, the evaluation of ventilation parameters and the most recent developments in computer simulation techniques of room airflow. It is hoped that the theme of ROOMVENT 2000 "Ventilation for Health and Sustainable Environment" will set the scene for room air distribution research and development for the new millennium.

Download or read book Energy Research Abstracts written by and published by . This book was released on 1994-02 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Full scale Experimental Characterization of a Non isothermal Realistic Air Jet for Building Ventilation written by Chi Kien Nguyen and published by . This book was released on 2019 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding room air distribution with coupled heat-air-moisture transport is essential to the design of building ventilation systems. In the past decades, although numerous research have been undertaken on air jet studies, there are still some issues that deserve a consideration. In fact, the majority of these studies focused on a symmetric arrangement of supply and exhaust air outlets with respect the room geometry. Besides, studies dealing with room coupled heat-air-moisture transport, which includes the condensation phenomenon on the room inner surface, are generally lacking in the literature. Hence, this work focuses on the following problematic: What is the behavior of a realistic air jet under interaction effects and how to characterize such air jets? In realistic indoor conditions promoting condensation on cold surface, would we be able to quantify the condensate mass flow rate? The two studies are experimentally investigated in the full-scale MINIBAT controlled test cell. The first part consists in characterizing a ceiling turbulent air jet in a realistic indoor airflow configuration. The experimental results show visible interaction effects of the room architectural elements on the air jet behavior: they have deviated the jet trajectory as well as deformed the jet cross-sectional shape. The jet main characteristics such as the spread rate, the velocity and temperature decay are quantified. A graphical-based method is proposed to quantify the jet shape deformation using a so-called deformation indicator. The second part of this work treats the phenomenon of moisture condensation on a glazing surface by reproducing a winter condition within the test cell. The condensation appearance and its growth mechanism are observed using a macro-photography technique. The image post-processing enabled to estimate the condensation rate. Comparisons between experimental and theoretical results show some agreement, which could validate the feasibility of imaging techniques in full-scale condensation studies.Detailed experimental data accompanied by well-known boundary conditions from this work could serve as a benchmark test for CFD models validation, in particular for asymmetric airflow configurations, with the presence of the condensation phenomenon.

Download or read book Ventilation of Buildings written by H.B. Awbi and published by Routledge. This book was released on 2004-06-02 with total page 535 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hazim Awbi's Ventilation of Buildings has become established as the definitive text on the subject. This new, thoroughly revised, edition builds on the basic principles of the original text drawing in the results of considerable new research in the field. A new chapter on natural ventilation is also added and recent developments in ventilation concepts and room air distribution are also considered. The text is intended for the practitioner in the building services industry, the architect, the postgraduate student undertaking courses or research in HVAC, building services engineering, or building environmental engineering, and the undergraduate studying building services as a major subject. Readers are assumed to be familiar with the basic principles of fluid flow and heat transfer and some of the material requires more advanced knowledge of partial differential equations which describe the turbulent flow and heat transfer processes of fluids. The book is both a presentation of the practical issues that are needed for modern ventilation system design and a survey of recent developments in the subject

Download or read book Ventilation of Buildings written by H.B. Awbi and published by Routledge. This book was released on 2004-06-02 with total page 537 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hazim Awbi's Ventilation of Buildings has become established as the definitive text on the subject. This new, thoroughly revised, edition builds on the basic principles of the original text drawing in the results of considerable new research in the field. A new chapter on natural ventilation is also added and recent developments in ventilation concepts and room air distribution are also considered. The text is intended for the practitioner in the building services industry, the architect, the postgraduate student undertaking courses or research in HVAC, building services engineering, or building environmental engineering, and the undergraduate studying building services as a major subject. Readers are assumed to be familiar with the basic principles of fluid flow and heat transfer and some of the material requires more advanced knowledge of partial differential equations which describe the turbulent flow and heat transfer processes of fluids. The book is both a presentation of the practical issues that are needed for modern ventilation system design and a survey of recent developments in the subject

Download or read book Proceedings of the ASME Fluids Engineering Division written by and published by . This book was released on 2002 with total page 798 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 1996 with total page 780 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 1960 with total page 1006 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Schlieren and Shadowgraph Techniques written by G.S. Settles and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: Schlieren and shadowgraph techniques are basic and valuable tools in various scientific and engineering disciplines. They allow us to see the invisible: the optical inhomogeneities in transparent media like air, water, and glass that otherwise cause only ghostly distortions of our normal vision. These techniques are discussed briefly in many books and papers, but there is no up-to-date complete treatment of the subject before now. The book is intended as a practical guide for those who want to use these methods, as well as a resource for a broad range of disciplines where scientific visualization is important. The colorful 400-year history of these methods is covered in an extensive introductory chapter accessible to all readers.

Download or read book Transactions of the ASAE written by American Society of Agricultural Engineers and published by . This book was released on 1996 with total page 1264 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Turbulent Jets and Plumes written by Joseph Hun-wei Lee and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: Jets and plumes are shear flows produced by momentum and buoyancy forces. Examples include smokestack emissions, fires and volcano eruptions, deep sea vents, thermals, sewage discharges, thermal effluents from power stations, and ocean dumping of sludge. Knowledge of turbulent mixing by jets and plumes is important for environmental control, impact and risk assessment. Turbulent Jets and Plumes introduces the fundamental concepts and develops a Lagrangian approach to model these shear flows. This theme persists throughout the text, starting from simple cases and building towards the practically important case of a turbulent buoyant jet in a density-stratified crossflow. Basic ideas are illustrated by ample use of flow visualization using the laser-induced fluorescence technique. The text includes many illustrative worked examples, comparisons of model predictions with laboratory and field data, and classroom tested problems. An interactive PC-based virtual-reality modelling software (VISJET) is also provided. Engineering and science students, researchers and practitioners may use the book both as an introduction to the subject and as a reference in hydraulics and environmental fluid mechanics.

Download or read book Industrial Ventilation Design Guidebook Volume 1 written by Howard D. Goodfellow and published by Academic Press. This book was released on 2020-07-24 with total page 581 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fully revised and restructured two-volume 2nd edition of the Industrial Ventilation Design Guidebook develops a systematic approach to the engineering design of industrial ventilation systems and provides engineers guidance on how to implement this state-of-the-art ventilation technology on a global basis.Volume 1: Fundamentals features the latest research technology in the broad field of ventilation for contaminant control including extensive updates of the foundational chapters from the previous edition.With major contributions by experts from Asia, Europe and North America in the global industrial ventilation field, this new edition is a valuable reference for consulting engineers working in the design of air pollution and sustainability for their industrial clients (processing and manufacturing), as well as mechanical, process and plant engineers looking for design methodologies and advice on sensors and control algorithms for specific industrial operations so they can meet challenging targets in the low carbon economy. - Presents practical designs for different types of industrial systems including descriptions and new designs for ducted systems - Discusses the basic processes of air and containment movements such as jets, plumes, and boundary flows inside ventilated spaces - Introduces the new concept of target levels in the systematic design methodology such as assessing target levels for key parameters of industrial air technology and the hierarchy of different target levels - Provides future directions and opportunities in the industrial design field

Download or read book Turbulent jets in confined spaces application in mixing ventilation experimental and numerical studies written by Taghi Karimipanah and published by . This book was released on 1996 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book International aerospace abstracts written by and published by . This book was released on 1993 with total page 1060 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flow Visualization written by Wolgang Merzkirch and published by Elsevier. This book was released on 2012-12-02 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flow Visualization, Second Edition focuses on developments, applications, and results in the field of flow visualization. Organized into four chapters, this book begins with the principles of flow visualization and image processing. Subsequent chapters describe the methods of flow visualization, particularly the addition of foreign material to the flowing fluid that might be gaseous or liquid; certain optical methods that are sensitive to changes of the index of refraction; and flow field marking by heat and energy addition.