TRANSPORT PHENOMENA AND UNIT OPERATIONS

TRANSPORT PHENOMENA AND UNIT OPERATIONS

TRANSPORT PHENOMENA AND UNIT OPERATIONS A COMBINED APPROACH Richard G. Griskey A JOHN WILEY & SONS, INC., PUBLICATION

This book is printed on acid-free paper Copyright 0 2002 by John Wiley and Sons, Inc, New York All rights reserved Published simultaneously in Canada. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recordlng, scanning or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 750-4744. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 605 Third Avenue, New York, NY 10158-0012, (212) 850-6011, fax (212) 850-6008, E-mail: PERMREQ@WILEY.COM. For ordering and customer service, call 1-800-CALL-WILEY. Library of Congress Cataloging-in-Publication Data: ISBN 0-47 1-43819-7 Printed in the United States of America. 109 8 7 6 54 3 2 *

To Engineering, the silent profession that produces progress

CONTENTS Preface Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Transport Processes and Transport Coefficients Fluid Flow Basic Equations Frictional Flow in Conduits Complex Flows Heat Transfer; Conduction Free and Forced Convective Heat Transfer Complex Heat Transfer Heat Exchangers Radiation Heat Transfer ix 1 23 55 83 106 127 157 179 208 Chapter 10 Mass Transfer; Molecular Diffusion Chapter 11 Convective Mass Transfer Coefficients Chapter 12 Equilibrium Staged Operations 228 249 274 vii

viii CONTENTS Chapter 13 Additional Staged Operations Chapter 14 Mechanical Separations Appendix A Appendix B Appendix C Appendix References Index 321 367 410 416 437 440 443

PREFACE The question of why another textbook, especially in the areas of transport processes and unit operations, is a reasonable one. To develop an answer, let us digress for a moment to consider Chemical Engineering from a historical perspective. In its earliest days, Chemical Engineering was really an applied or industrial chemistry. As such, it was based on the study of definitive processes (the Unit Process approach). Later it became apparent to the profession s pioneers that regardless of process, certain aspects such as fluid flow, heat transfer, mixing, and separation technology were common to many, if not virtually all, processes. This perception led to the development of the Unit Operations approach, which essentially replaced the Unit Processes-based curriculum. While the Unit Operations were based on first principles, they represented nonetheless a semiempirical approach to the subject areas covered. A series of events then resulted in another evolutionary response, namely, the concept of the Transport Phenomena that truly represented Engineering Sciences. No one or nothing lives in isolation. Probably nowhere is this as true as in all forms of education. Massive changes in the preparation and sophistication of students - as, for example in mathematics -provided an enthusiastic and skilled audience. Another sometimes neglected aspect was the movement of chemistry into new areas and approaches. As a particular example, consider Physical Chemistry, which not only moved from a macroscopic to a microscopic approach but also effectively abandoned many areas in the process. ix

X PREFACE Furthermore, other disciplines of engineering were moving as well in the direction of Engineering Science and toward a more fundamental approach. These and other factors combined to make the next movement a reality. The trigger was the classic text, Transport Phenomena, authored by Bird, Stewart, and Lightfoot. The book changed forever the landscape of Chemical Engineering. At this point it might seem that the issue was settled and that Transport Phenomena would predominate. Alas, we find that Machiavelli s observation that Things are not what they seem is operable even in terms of Chemical Engineering curricula. The Transport Phenomena approach is clearly an essential course for graduate students. However, in the undergraduate curriculum there was a definite division with many departments keeping the Unit Operations approach. Even where the Transport Phenomena was used at the undergraduate level there were segments of the Unit Operations (particularly stagewise operations) that were still used. Experience with Transport Phenomena at the undergraduate level also seemed to produce a wide variety of responses from enthusiasm to lethargy on the part of faculty. Some institutions even taught both Transport Phenomena and much of the Unit Operations (often in courses not bearing that name). Hence, there is a definite dichotomy in the teaching of these subjects to undergraduates. The purpose of this text is hopefully to resolve this dilemma by the mechanism of a seamless and smooth combination of Transport Phenomena and Unit Operations. The simplest statement of purpose is to move from the fundamental approach through the semiempirical and empirical approaches that are frequently needed by a practicing professional Chemical Engineer. This is done with a minimum of derivation but nonetheless no lack of vigor. Numerous worked examples are presented throughout the text. A particularly important feature of this book is the inclusion of comprehensive problem sets at the end of each chapter. In all, over 570 such problems are presented that hopefully afford the student the opportunity to put theory into practice. A course using this text can take two basically different approaches. Both start with Chapter 1, which covers the transport processes and coefficients. Next, the areas of fluid flow, heat transfer, and mass transfer can be each considered in turn (i.e., Chapter 1, 2, 3,..., 13, 14). The other approach would be to follow as a possible sequence 1, 2, 5, 10, 3, 6, 11, 4, 7, 8, 9, 12, 13, 14. This would combine groupings of similar material in the three major areas (fluid flow, heat transfer, mass transfer) finishing with Chapters 12, 13, and 14 in the area of separations. The foregoing is in the nature of a suggestion. There obviously can be many varied approaches. In fact, the text s combination of rigor and flexibility would give a faculty member the ability to develop a different and challenging course.

PREFACE xi It is also hoped that the text will appeal to practicing professionals of many disciplines as a useful reference text. In this instance the many worked examples, along with the comprehensive compilation of data in the Appendixes, should prove helpful. Richard G. Griskey Summit, NJ