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Air distribution in buildings PDF

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Mechanical engineering Air Distribution Air Distribution in Buildings in Buildings Air Distribution in Buildings is a concise and practical guide to air distribution system design and managing air conditioning systems in buildings. Making use of 40 years of experience in the design of air conditioning and ventilation systems, and other electromechanical services, this structured reference for built environment engineering offers in-depth coverage of air distribution technology. The text brings together a wide range of information and offers technical guidance on the design, calculation, and efficient operation of air distribution in buildings. The text highlights the special characteristics of air distribution in individual spaces. It presents the basic and fundamental concepts of air distribution as it relates to grilles and outlets, room space, and buildings. It focuses on air distribution systems in large buildings, starting with simple rooms and then moving on to more complex configurations. It also sums up the latest standards and best practices in air conditioning engineering. • Includes knowledge of the new trends in buildings’ air distribution • Provides systematic analyses of the air flow regimes, heat transfer, and relative humidity in a collection of special built environments • Presents energy analyses of the air conditioning systems for operating theaters and sporting facilities in unusual and severe climatic conditions • Offers a description of flow characteristics in archeological monuments with emphasis on combating excessive moisture • Introduces examples of very dense occupancy built environments, moisture sensitive environments, and open space air conditioning • Details advanced treatment of flow characterization in large public buildings This text serves as an ideal resource for air conditioning engineers, contractors, and consultants. It also benefits mechanical and architectural engineering students. Essam E. Khalil K20683 ISBN-13: 978-1-4665-9463-0 90000 9 781466 594630 K20683_Cover_mech.indd All Pages 10/15/13 10:18 AM Air Distribution in Buildings Essam E. Khalil Boca Raton London New York CRC Press is an imprint of the Taylor & Francis Group, an informa business MECHANICAL and AEROSPACE ENGINEERING Frank Kreith & Darrell W. Pepper Series Editors RECENTLY PUBLISHED TITLES Air Distribution in Buildings, Essam E. Khalil Alternative Fuels for Transportation, Edited by Arumugam S. Ramadhas Computer Techniques in Vibration, Edited by Clarence W. de Silva Distributed Generation: The Power Paradigm for the New Millennium, Edited by Anne-Marie Borbely and Jan F. Kreider Elastic Waves in Composite Media and Structures: With Applications to Ultrasonic Nondestructive Evaluation, Subhendu K. Datta and Arvind H. Shah Elastoplasticity Theory, Vlado A. Lubarda Energy Audit of Building Systems: An Engineering Approach, Moncef Krarti Energy Conversion, Edited by D. 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Lakes Weatherization and Energy Efficiency Improvement for Existing Homes: An Engineering Approach, Moncef Krarti CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2014 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Version Date: 20130930 International Standard Book Number-13: 978-1-4665-9465-4 (eBook - PDF) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmit- ted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright. com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. 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Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com Contents Preface ...................................................................................................................xiii Acknowledgments ................................................................................................xv About the Author ...............................................................................................xvii 1 Air Distribution Systems ..............................................................................1 1.1 Airflow Patterns ....................................................................................1 1.1.1 General ......................................................................................1 1.1.2 Practical Configurations .........................................................3 1.1.2.1 Grilles and Diffusers ...............................................3 1.1.2.2 Square Ceiling Diffuser with a Circular Duct Connection .......................................................8 1.1.2.3 Wall-Mounted Supply Grille ..................................8 1.1.2.4 Ceiling Architectural Diffuser ...............................9 1.1.2.5 Square Ceiling Diffuser.........................................10 1.1.2.6 High Ceiling Diffusers ..........................................10 1.1.2.7 Fixed Swirl Diffusers for Ceiling Installations ....10 1.2 Airflow Efficiency in Rooms .............................................................11 1.3 Noise Criteria .......................................................................................15 1.4 Air Handling Units .............................................................................18 1.4.1 Casing ......................................................................................18 1.4.2 Mixing Box ..............................................................................19 1.4.3 Filter Sections .........................................................................19 1.4.4 Coil Section Two-Pipe System ..............................................19 1.4.5 Electric Heater Section ..........................................................19 1.4.6 Fan Section ..............................................................................20 References .......................................................................................................20 2 Mathematical Modeling Technique .........................................................23 2.1 Governing Equations ..........................................................................23 2.1.1 Conservation of Mass: The Continuity Equation ..............23 2.1.1.1 Derivation of the Continuity Equation ...............23 2.1.1.2 Differential Form of the Continuity Equation ....24 2.1.2 Newton’s Second Law: The Linear Momentum Equation ..................................................................................26 2.1.2.1 Derivation of the Linear Momentum Equation ....26 2.1.2.2 Description of Forces Acting on Differential Element ...............................................28 2.1.2.3 Equations of Motion ...............................................30 2.1.2.4 Viscous Flow ...........................................................30 2.1.2.5 Stress–Deformation Relationships .......................30 © 2008 Taylor & Francis Group, LLC v vi Contents 2.1.2.6 Navier–Stokes Equations ......................................31 2.1.3 First Law of Thermodynamics: The Energy Equation .....32 2.1.3.1 Derivation of the Energy Equation ......................32 2.1.3.2 Differential Form ....................................................32 2.2 Numerical Procedure .........................................................................33 2.2.1 Differential Equations of Motion .........................................33 2.2.2 Turbulence Model ..................................................................36 2.2.3 Wall Functions........................................................................39 2.2.4 Numerical Solution Procedure ............................................41 2.2.5 Finite Difference Equations ..................................................43 2.2.6 Solution Algorithm ................................................................44 2.2.6.1 Convergence and Stability ....................................45 2.3 Conclusions ..........................................................................................45 References .......................................................................................................46 3 Airflow Regimes and Thermal Comfort in a Room ..............................47 3.1 Numerical Model ................................................................................47 3.1.1 Case Geometry .......................................................................47 3.1.2 Boundary Conditions ............................................................48 3.1.2.1 Walls .........................................................................48 3.1.2.2 Interior .....................................................................48 3.1.2.3 Supply Grilles .........................................................48 3.1.2.4 Light Heat Load ......................................................49 3.1.2.5 Human Body ...........................................................49 3.1.2.6 Return Grilles .........................................................50 3.1.2.7 Television Heat Load .............................................50 3.2 Flow Pattern and Thermal Behavior ................................................51 3.2.1 General ....................................................................................51 3.2.2 Design Alternatives ...............................................................51 3.2.2.1 Design 1 ...................................................................51 3.2.2.2 Design 2: Square Diffuser (60–30–15°) ................53 3.2.2.3 Design 3: Square Diffuser (90–60–30°) ................53 3.2.2.4 Design 4: Circular Diffuser (90–60–30°) .............56 3.2.2.5 Design 5: Swirl Flow ..............................................59 3.2.2.6 Design 6: Side Return ............................................61 3.2.2.7 Design 7: Side Supply .............................................64 3.3 Conclusions ..........................................................................................67 References .......................................................................................................68 4 Airflow Regimes and Thermal Pattern in Archeological Monuments .........................................................................69 4.1 Historical Background .......................................................................70 4.1.1 General ....................................................................................70 4.1.1.1 External Factors ......................................................70 4.1.1.2 Internal Factors .......................................................70 © 2008 Taylor & Francis Group, LLC Contents vii 4.1.2 Main Factors Affecting Human Comfort ...........................73 4.2 Background ..........................................................................................73 4.2.1 General ....................................................................................73 4.2.2 Ventilation in Archeological Tombs of Valley of the Kings, Luxor ...........................................................................73 4.2.2.1 Omar Abdel-Aziz and Khalil (2005) ....................73 4.2.2.2 Ezzeldin and Khalil (2006) ....................................77 4.3 Proposed Design Calculation Methodology ...................................81 4.3.1 General ....................................................................................81 4.3.2 Classification of Tombs .........................................................82 4.3.2.1 Rameses VII Tomb (KV1) ......................................83 4.3.2.2 Rameses IV Tomb (KV2) ........................................84 4.3.2.3 Bay Tomb (KV13) ....................................................84 4.3.2.4 Seti II Tomb (KV15) ................................................85 4.3.3 Mesh Generation ....................................................................88 4.3.4 Computational Design Studies ............................................89 4.3.5 Boundary Conditions ............................................................91 4.3.5.1 Inlet Air Conditions ...............................................91 4.3.5.2 Outlets ......................................................................91 4.3.5.3 Walls .........................................................................91 4.3.5.4 Visitors .....................................................................91 4.4 Proposed Solution ...............................................................................92 4.4.1 Investigate Decay Mechanisms and Causes ......................92 4.4.2 Design and Construction of Effective Ventilation System for Protection and Preservation .........95 4.5 Conclusions ..........................................................................................97 References .......................................................................................................97 Recommended Readings ..............................................................................98 5 Airflow in Places of Worship ...................................................................101 5.1 People and Comfort ..........................................................................102 5.1.1 Comfort Criteria ...................................................................102 5.1.2 Effect of Air Movement .......................................................102 5.1.3 Acceptable Comfort Zone ...................................................102 5.2 Climatic Factors .................................................................................102 5.2.1 Climatic Elements Affecting Natural Cooling ................102 5.2.2 Extrapolating Regional Weather Data to Specific Sites ....103 5.2.2.1 Humidity ...............................................................103 5.2.2.2 Solar Radiation .....................................................103 5.2.2.3 Temperature ..........................................................103 5.2.2.4 Wind .......................................................................103 5.3 Air Conditioning of Mosques: Ceiling Designs ...........................103 5.4 Air Conditioning of Churches: Ceiling Designs ..........................106 5.4.1 Model Architecture (Structure) .........................................107 5.4.1.1 Inlet Air Conditions .............................................107 © 2008 Taylor & Francis Group, LLC viii Contents 5.4.1.2 Air Inlets and Outlets ..........................................109 5.4.1.3 Walls .......................................................................109 5.4.1.4 Visitors’ Bodies and Faces ...................................109 5.4.2 Velocity Predictions .............................................................109 5.5 Air Distribution in Mosques: Free-Stand Units ............................117 5.6 Conclusions ........................................................................................122 References .....................................................................................................122 6 Airflow Patterns in Healthcare Facilities ...............................................123 6.1 Airflow Characteristics for Comfort ..............................................123 6.2 Early Practice of Airflow Design ....................................................124 6.3 Present Observations ........................................................................125 6.4 Problem Analysis ..............................................................................126 6.5 Modeled Equations ...........................................................................127 6.6 Flow Pattern Analyses ......................................................................130 6.6.1 Experimental Facility ..........................................................131 6.6.2 Numerical Program .............................................................132 6.7 Conclusions ........................................................................................137 References .....................................................................................................139 Recommended Readings ............................................................................139 7 Examples of Typical Air Conditioning Projects ...................................143 7.1 Environmental Control ....................................................................143 7.1.1 Temperatures ........................................................................143 7.1.2 Relative Humidity Control .................................................143 7.1.3 Airflow Velocity Control .....................................................144 7.1.4 Ventilation .............................................................................144 7.2 Air Filtration ......................................................................................145 7.3 Pressure Relationships and Ventilation .........................................145 7.4 Air Movement ....................................................................................147 7.5 Air Quality .........................................................................................147 7.6 Smoke Control ...................................................................................148 7.7 Fire Control ........................................................................................148 7.8 Noise Criteria .....................................................................................149 7.9 Factors Affecting System Selection ................................................149 7.9.1 General Design Factors .......................................................149 7.9.2 Load Characteristics ............................................................150 7.9.3 Design Factors ......................................................................151 7.9.3.1 Comfort Level .......................................................151 7.9.3.2 Costs .......................................................................151 7.9.3.3 Local Conditions ..................................................152 7.9.3.4 Automatic Temperature Control ........................152 7.9.3.5 Fire, Smoke, and Odor Control ...........................152 7.10 HVAC Life Cycle Cost Analyses .....................................................152 7.10.1 Introduction ..........................................................................152 © 2008 Taylor & Francis Group, LLC Contents ix 7.10.2 Owning Costs Analysis ......................................................154 7.10.3 Operating Costs Analysis ...................................................155 7.10.4 Maintenance Costs Analysis ..............................................156 7.10.5 Design Specifications ..........................................................156 7.11 Further Examples ..............................................................................157 7.12 Engineering Tips for Energy-Efficient Buildings .........................168 7.13 Conclusions ........................................................................................169 References .....................................................................................................170 8 Indoor Environmental Quality ................................................................171 8.1 Definitions ..........................................................................................171 8.2 IEQ Mandatory Provisions ..............................................................173 8.2.1 Indoor Air Quality ...............................................................174 8.2.2 Minimum Ventilation Rates ...............................................174 8.2.3 Outdoor Air Delivery Monitoring .....................................174 8.2.3.1 Spaces Ventilated by Mechanical Systems .......174 8.2.3.2 Naturally Ventilated Spaces ................................175 8.2.3.3 CO Sensors ...........................................................175 2 8.2.4 Filtration and Air Cleaner Requirements .........................176 8.2.4.1 Particulate Matter .................................................176 8.2.4.2 Ozone .....................................................................176 8.2.4.3 Bypass Pathways ..................................................176 8.2.5 Environmental Tobacco Smoke ..........................................176 8.2.6 Building Entrances ..............................................................176 8.2.6.1 Scraper Surface .....................................................177 8.2.6.2 Absorption Surface ..............................................177 8.2.6.3 Finishing Surface ..................................................177 8.3 Thermal Environmental Conditions for Human Occupancy Comfort ..........................................................................177 8.4 Acoustical Control ............................................................................178 8.4.1 Exterior Sound ......................................................................178 8.4.2 Interior Sound ......................................................................178 8.4.3 Outdoor–Indoor Transmission Class and Sound Transmission Class ..............................................................179 8.5 Daylighting by Top Lighting ...........................................................179 8.5.1 Minimum Daylight Zone by Top Lighting ......................179 8.5.2 Skylight Characteristics ......................................................179 8.6 Isolation of the Building from Pollutants in Soil ..........................180 8.7 Prescriptive Option ...........................................................................180 8.7.1 Daylighting by Side Lighting .............................................180 8.7.1.1 Minimum Effective Aperture .............................180 8.7.1.2 Office Space Shading ...........................................181 8.7.2 Materials ................................................................................182 8.7.2.1 Adhesives and Sealants .......................................182 8.7.2.2 VOC Content Requirements ...............................182 © 2008 Taylor & Francis Group, LLC

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