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Control Systems for Heating, Ventilating, and Air Conditioning PDF

317 Pages·1993·7.531 MB·English
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Control Systems for Heating, Ventilating, and Air Conditioning Fifth Edition w. Roger Haines Consultant and Douglas C. Hittle Director, Solar Energy Applications Laboratory Colorado State University ca Ft. Collins, SPRINGER SCIENCE+BUSINESS MEDIA, LLC Copyright © 1993 by Springer Science+Busincss Media New York Originally published by Van Nostrand Reinhold in 1993 AU rights reserved. No part ofthis book covered by the copyright hereon may be reproduced or used in any fonn or by any means--graphic, de,,'tronic. <.lr mechanical, including photocopying, recording, taping, or information storage arul retrieval systerns--without the written permission ofthe puhlisher. J 4 5 6 7 8 9 XXX 01 00 99 98 97 96 Lihrary ofCongress Cataloging-in-Publication Data Haincs. Roger W. Control systems for heating, ventilating, and air conditioning, 5/e. Bibliography: p. lncludes index. ISBN 978-1-4613-6359-0 ISBN 978-1-4615-3108-1 (eBook) DOI 10.1007/978-1-4615-3108-1 1. Heating--Control. 2. Air conditioning--Control. 1. Title. TII7466.5.H34 1993 82-11015 Vuit Chapman & Hall on the Internet http://www.chaphaLLcomichapha/Llltml Contents Preface to the First Edition ix Preface to the Fifth Edition xi Chapter 1 Control Theory and Terminology 1 1.1 INTRODUCTION 1 1.2 WHAT IS "CONTROL"? 2 1.3 ELEMENTARY CONTROL SYSTEM 2 1.4 PURPOSES OF CONTROL 3 1.5 CONTROL ACTION 4 1.6 ENERGY SOURCES FOR CONTROL SYSTEMS 9 1.7 MEASUREMENT 10 1.8 SYMBOLS AND ABBREVIATIONS 11 1.9 PSYCHROMETRICS 11 1.10 RELATIONSHIPS 11 1.11 SUMMARY 12 Chapter 2 Pneumatic Control Devices 13 2.1 INTRODUCTION 13 2.2 PNEUMATIC CONTROL DEVICES 13 2.3 CONTROL CABINETS 38 2.4 AIR SUPPLY 38 III iv Contents Chapter 3 Electric and Electronic Control Devices 42 3.1 ELECTRIC CONTROL DEVICES 42 3.2 ELECTRONIC CONTROL DEVICES 55 Chapter 4 Fluidic Control Devices 68 4.1 INTRODUCTION 68 4.2 WALL ATTACHMENT DEVICES 68 4.3 TURBULENCE AMPLIFIERS 70 4.4 VORTEX AMPLIFIERS 71 4.5 RADIAL JET AMPLIFIER 71 4.6 FLUIDIC TRANSDUCERS 72 4.7 MANUAL SWITCHES 73 Chapter 5 Flow Control Devices 75 5.1 DAMPERS 75 5.2 STEAM AND WATER FLOW CONTROL VALVES 79 Chapter 6 Elementary Control Systems 93 6.1 INTRODUCTION 93 6.2 OUTSIDE AIR CONTROLS 93 6.3 AIR STRATIFICATION 98 6.4 HEATING 100 6.5 COOLING COILS 105 6.6 HUMIDITY CONTROL 110 6.7 DEHUMIDIFIERS 118 6.8 STATIC PRESSURE CONTROL 119 6.9 ELECTRIC HEAT 120 6.10 GAS-FIRED HEATERS 123 6.11 OIL-FIRED HEATERS 125 6.12 REFRIGERATION EQUIPMENT 125 6.13 FIRE AND SMOKE CONTROL 131 6.14 ELECTRICAL INTERLOCKS 133 6.15 LOCATION OF SENSORS 133 6.16 SUMMARY 134 Contents v Chapter 7 Complete Control Systems 135 7.1 INTRODUCTION 135 7.2 SINGLE-ZONE SYSTEMS 135 7.3 MULTIZONE AIR HANDLING SYSTEMS 143 7.4 DUAL-DUCT SYSTEMS 157 7.5 VARIABLE-VOLUME SYSTEMS 162 7.6 REHEAT SYSTEMS 170 7.7 HEAT RECLAIM 170 7.8 FAN-COIL UNITS 178 7.9 INDUCTION SYSTEMS 183 7.10 UNIT VENTILATORS 184 7.11 PACKAGED EQUIPMENT 186 7.12 OTHER PACKAGED EQUIPMENT 189 7.13 RADIANT HEATING AND COOLING 191 7.14 RADIATORS AND CONVECTORS 193 7.15 HEAT EXCHANGERS 194 7.16 SOLAR HEATING AND COOLING SYSTEMS 198 7.17 SUMMARY 199 Chapter 8 Electric Control Systems 200 8.1 INTRODUCTION 200 8.2 ELECTRIC CONTROL DIAGRAMS 200 8.3 ELECTRICAL CONTROL OF A CHILLER 203 8.4 ELECTRICAL CONTROL OF AN AIR HANDLING UNIT 206 8.5 EXAMPLE: A TYPICAL SMALL AIR- CONDITIONING SYSTEM 206 8.6 ELECTRIC HEATERS 207 8.7 REDUCED-VOLTAGE STARTERS 211 8.8 MULTISPEED STARTERS 216 8.9 VARIABLE SPEED CONTROLLERS 219 8.10 SUMMARY 220 Chapter 9 Special Control 221 9.1 INTRODUCTION 221 9.2 CLOSE TEMPERATURE AND/OR HUMID ITY CONTROL 221 vi Contents 9.3 CONTROLLED ENVIRONMENT ROOMS FOR TESTING 227 9.4 SUMMARY 230 Chapter 10 Digital and Supervisory Control Systems 231 10.1 INTRODUCfION 231 10.2 HARD-WIRED SYSTEMS 231 10.3 MULTIPLEXING SYSTEMS 232 10.4 COMPUTER-BASED SYSTEMS FOR MONITORING AND CONTROL 232 10.5 BENEFITS OF THE COMPUTER SYSTEM 239 10.6 TRAINING FOR MAINTENANCE AND OPERATION 240 10.7 SUMMARY 240 Chapter 11 Psychrometries 242 11.1 INTRODUCfION 242 11.2 PSYCHROMETRIC PROPERTIES 242 11.3 PSYCHROMETRIC TABLES 244 11.4 PSYCHROMETRIC CHARTS 244 11.5 PROCESSES ON THE PSYCHROMETRIC CHART 246 11.6 HVAC CYCLES ON THE CHART 250 11.7 IMPOSSIBLE PROCESSES 252 11.8 EFFECfS OF ALTITUDE 253 11.9 SUMMARY 254 Chapter 12 Central Plant Pumping and Distribution Systems 255 12.1 INTRODUCfION 255 12.2 DIVERSITY 255 12.3 CONSTANT FLOW SYSTEMS 256 12.4 VARIABLE FLOW SYSTEMS 257 12.5 DISTRIBUTION SYSTEMS 259 12.6 BUILDING INTERFACES 263 12.7 SUMMARY 264 Contents vii Chapter 13 Retrofit of Existing Control Systems 265 13.1 INTRODUCTION 265 13.2 ECONOMIC ANALYSIS 265 13.3 DISCRIMINATORS 265 13.4 CONTROL MODES 266 13.5 ECONOMY CYCLE CONTROLS 266 13.6 SINGLE-ZONE SYSTEMS 266 13.7 REHEAT SYSTEMS 270 13.8 MULTIZONE SYSTEMS 270 13.9 DUAL-DUCT SYSTEMS 274 13.10 SYSTEMS WITH HUMIDITY CONTROL 276 13.11 CONTROL VALVES AND PUMPING ARRANGEMENTS 278 13.12 SUMMARY 279 Chapter 14 Dynamic Response and Tuning 280 14.1 INTRODUCTION 280 14.2 DYNAMIC RESPONSE 281 14.3 TUNING HVAC CONTROL LOOPS 282 14.4 SUMMARY 288 Bibliography 289 Abbreviations Used in This Book 292 Symbols Used in This Book 293 Index 301 Preface to the First Edition This book is intended for the guidance of the engineer who is designing a heating, ventilating or air conditioning system and wants a simple, practical explanation of how best to control that system. It could also be used as a supplemental text in a college or technical school course on refrigeration and air conditioning. It does not include mathematical analyses of control systems, response factors, Fourier transforms and the like. These are adequately and thoroughly covered in a number of up-to-date college-level texts. What is presented here is an elementary but comprehensive explanation of control system theory, control hardware, and both simple and complex control systems. There are also discussions on supervisory controls and the use of computers in control systems. Throughout, the reader should be aware of the interrelationship between the HVAC controls, the HVAC system, the electrical power system and the building. There have been examples of control systems which failed to control because inherent deficiences in the building or HVAC system made it uncon trollable; or of control failures because the designer failed to make his intent clear to others. It is hoped that the reader will be helped to avoid some of these pitfalls. Roger W. Haines January, 1971 ix Preface to the Fifth Edition Roger Haines wrote in the Preface to the Fourth Edition that a new edition was needed because technology changes so fast and that there is always something new to learn. Roger and I have been teaching short courses together for quite awhile. Before the Fourth Edition of Roger's book came out I was seriously thinking about writing my own book. After all, I had design experience and was doing research on controls at the Construction Engineering Research Laboratory, Champaign, Illinois. Most everything I had presented about new concepts and products in HVAC controls between 1983 and 1986 was in Roger's Fourth Edition (the book came out in 1987, but it takes a lot longer to go from manuscript to published book). I was devastated. All of our obscure research results were now published in a semi-popular book. Well why not. Roger was trying to do his readers a service and if you are out of date you are history. Roger stayed current and my ambitions to do my own book were history. Luckily, if you have sold all the Fourth Editions to all the people who are likely to buy them, the publisher gives you a call and says it's time for a Fifth Edition. Besides, there really had been some important work on HVAC control going on at Universities and in the back rooms at control companies in the interim. When Roger called me and asked if I would consider revising his book I was very pleased. Here is a partial list of new material covered in this Fifth Edition: 1. Formulas and graphs. Math to allow you to determine the relationship between damper position and flow rate, for example. Derivations of how valve authority effects control system performance as another example. xi xii Preface 2. Much more on applications. This edition tries to give the pros and cons of various control options. Energy consumption is one issue, maintainability is also considered. An example of some of the revisions is the completely new section on controlling variable-air-volume flow rates. 3. A revised discussion on digital control and central monitoring. If we print the book fast enough this chapter will still be up-to-date. 4. A new chapter on dynamic response and control system tuning. Those who master this chapter will be highly valued when it comes time to make a real control system work. I hope you can identify even more new material. Also, like Roger, I hope you will help me learn. Please call me at (970-491-8617) if you have new information that I should consider for the sixth edition. Doug Hittle

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