This book teaches the fundamentals of fluid flow by including both theory and the applications of fluid flow in chemical engineering. It puts fluid flow in the context of other transport phenomena such as mass transfer and heat transfer, while covering the basics, from elementary flow mechanics to the law of conservation. The book then examines the applications of fluid flow, from laminar flow to filtration and ventilization. It closes with a discussion of special topics related to fluid flow, including environmental concerns and the economic reality of fluid flow applications.
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Half Title page
Part I: Introduction to Fluid Flow
Chapter 1: History of Chemical Engineering—Fluid Flow
1.2 Fluid Flow
1.3 Chemical Engineering
Chapter 2: Units and Dimensional Analysis
2.2 Dimensional Analysis
2.3 Buckingham Pi (π) Theorem
2.4 Scale-Up and Similarity
Chapter 3: Key Terms and Definitions
Chapter 4: Transport Phenomena Versus Unit Operations
4.2 The Differences
4.3 What Is Engineering?
Chapter 5: Newtonian Fluids
5.2 Newton’S Law of Viscosity
5.3 Viscosity Measurements
5.4 Microscopic Approach
Chapter 6: Non-Newtonian Flow
6.2 Classification of Non-Newtonian Fluids
6.3 Microscopic Approach
Part II: Basic Laws
Chapter 7: Conservation Law For Mass
7.2 Conservation of Mass
7.3 Microscopic Approach
Chapter 8: Conservation Law For Energy
8.2 Conservation of Energy
8.3 Total Energy Balance Equation
Chapter 9: Conservation Law For Momentum
9.1 Momentum Balances
9.2 Microscopic Approach: Equation of Momentum Transfer
Chapter 10: Law of Hydrostatics(1)
10.2 Pressure Principles
10.3 Manometry Principles
Chapter 11: Ideal Gas Law
11.2 Boyle’S and Charles’ Laws
11.3 The Ideal Gas Law
11.4 Non-Ideal Gas Behavior
Part III: Fluid Flow Classification
Chapter 12: Flow Mechanisms
12.2 The Reynolds Number
12.3 Strain Rate, Shear Rate, and Velocity Profile
12.4 Velocity Profile and Average Velocity
Chapter 13: Laminar Flow in Pipes
13.2 Friction Losses
13.3 Tube Size
13.4 Other Considerations
13.5 Microscopic Approach
Chapter 14: Turbulent Flow in Pipes
14.2 Describing Equations
14.3 Relative Roughness in Pipes
14.4 Friction Factor Equations
14.5 Other Considerations
14.6 Flow Through Several Pipes
14.7 General Predictive and Design Approaches
14.8 Microscopic Approach
Chapter 15: Compressible and Sonic Flow
15.2 Compressible Flow
15.3 Sonic Flow
15.4 Pressure Drop Equations
Chapter 16: Two-Phase Flow
16.2 Gas (G)–-Liquid (L) Flow Principles: Generalized Approach
16.3 Gas (Turbulent) Flow–-Liquid (Turbulent) Flow
16.4 Gas (Turbulent) Flow–-Liquid (Viscous) Flow
16.5 Gas (Viscous) Flow–-Liquid (Viscous) Flow
16.6 Gas–-solid Flow
Part IV: Fluid Flow Transport and Applications
Chapter 17: Prime Movers
Chapter 18: Valves and Fittings
18.3 Expansion and Contraction Effects
18.4 Calculating Losses of Valves and Fittings
18.5 Fluid Flow Experiment: Data and Calculations
Chapter 19: Flow Measurement
19.2 Manometry and Pressure Measurements
19.3 Pitot Tube
19.4 Venturi Meter
19.5 Orifice Meter
19.6 Selection Process
Chapter 20: Ventilation
20.2 Indoor Air Quality
20.3 Indoor Air/Ambient Air Comparison
20.4 Industrial Ventilation Systems
Chapter 21: Academic Applications
Chapter 22: Industrial Applications
Part V: Fluid-Particle Applications
Chapter 23: Particle Dynamics
23.2 Particle Classification and Measurement
23.3 Drag Force
23.4 Particle Force Balance
23.5 Cunningham Correction Factor
23.6 Liquid-Particle Systems
23.7 Drag on A Flat Plate
Chapter 24: Sedimentation, Centrifugation, Flotation
24.3 Hydrostatic Equilibrium in Centrifugation
Chapter 25: Porous Media and Packed Beds
25.3 Flow Regimes
Chapter 26: Fluidization
26.2 Fixed Beds(2)
26.4 Minimum Fluidization Velocity
26.5 Bed Height, Pressure Drop and Porosity
26.6 Fluidization Modes
26.7 Fluidization Experiment Data and Calculations
Chapter 27: Filtration
27.2 Filtration Equipment
27.3 Describing Equations
27.4 Filtration Experimental Data and Calculations
Part VI: Special Topics
Chapter 28: Environmental Management
28.2 Environmental Management History
28.3 Environmental Management Topics
Chapter 29: Accident and Emergency Management
29.3 Health Risk Assessment(5-7)
29.4 Hazard Risk Assessment(4-7)
29.5 Illustrative Examples
Chapter 30: Ethics
30.2 Teaching Ethics
30.3 Case Study Approach
30.5 Moral Issues(6)
30.7 Engineering and Environmental Ethics(9)
Chapter 31: Numerical Methods
31.2 Early History
31.3 Simultaneous Linear Algebraic Equations
31.4 Nonlinear Algebraic Equations
31.5 Numerical Integration
Chapter 32: Economics and Finance
32.2 The Need For Economic Analyses
32.4 Principles of Accounting(3)
Chapter 33: Biomedical Engineering
33.4 Blood Vessels
33.6 Plasma/Cell Flow
33.7 Biomedical Engineering Opportunities
Chapter 34: Open-Ended Problems
34.2 Developing Students’ Power of Critical Thinking(4)
34.5 Inquiring Minds
34.6 Angels on A Pin(10)
FLUID FLOW FOR THE PRACTICING CHEMICAL ENGINEER
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Published by John Wiley & Sons, Inc., Hoboken, New JerseyPublished simultaneously in Canada
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Library of Congress Cataloging-in-Publication Data:
Abulencia, James P.Fluid flow for the practicing chemical engineer / James P. Abulencia, Louis Theodore.p. cm.Includes index.ISBN 978-0-470-31763-1 (cloth)1. Fluid mechanics. 2. Fluidization. I. Title.TP156.F6T44 2009660.01’532051–dc222008048336
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Persons attempting to find a motive in this narrative will be prosecuted;
Persons attempting to find a moral in it will be banished;
Persons attempting to find a plot in it will be shot
By order of the Author, Mark Twain (Samuel Langhorne Clemens, 1835-1910), Adventures of Huckleberry Finn
It is becoming more and more apparent that engineering education must provide courses that will include material the engineering student will need and use both professionally and socially later in life. It is no secret that the teaching of Unit Operations—fluid flow, heat transfer, and mass transfer—is now required in any chemical engineering curriculum and is generally accepted as one of the key courses in applied engineering. In addition, this course, or its equivalent, is now slowly and justifiably finding its way into other engineering curricula.
Chemical engineering has traditionally been defined as a synthesis of chemistry, physics and mathematics, tempered with a concern for the dollar sign and applied in the service of humanity. During the 120 years (since 1888) that the profession has been in existence as a separate branch of engineering, humanity’s needs have changed tremendously and so has chemical engineering. Thus it is that today, this changing profession faces a challenge and an opportunity to put to better use the advances that have occurred since its birth.
The teaching of Unit Operations at the undergraduate level has remained relatively static since the publication of several early to mid-1900 texts. At this time, however, these and some of the more recent texts in this field are considered by many to be too advanced and of questionable value for the undergraduate engineering student. The present text is the first of three texts to treat the three aforementioned unit operations—fluid flow, heat transfer, and mass transfer. This initial treatise has been written in order to offer the reader the fundamentals of fluid flow with appropriate practical applications, and to possibly serve as an introduction to the specialized and more sophisticated texts in this area.
It is no secret that the teaching of both stoichiometry (material and energy balances) and the three unit operations, including fluid flow, has been a major factor in the success of chemical engineers and chemical engineering since the early 1900s. The authors believe that the approach presented here is a logical step in the continual evolution of this subject that has come to be defined as a unit operation. This “new” treatment of fluid flow is offered in the belief that it will be more effective in training engineers for successful careers in and/or out of the chemical process industry.
The present book has primarily evolved from notes, illustrative examples, problems and exams prepared by the authors for a required three semester fluid flow course given to chemical engineering students at Manhattan College. The course is also offered as an elective to other engineering disciplines in the school and has occasionally been attended by students outside the Department. It is assumed the student has already taken basic college physics and chemistry, and should have as a minimum background in mathematics courses through differential equations.
The course at Manhattan roughly places equal emphasis on principles and applications. However, depending on the needs and desires of the lecturer, either area may be emphasized, and the material in this text is presented in a manner to permit this. Further, no engineering tool is complete without information on how to use it. By the same token, no engineering text is complete without illustrative examples that serve the important purpose of demonstrating the use of the procedures, equations, tables, graphs, etc., presented in the text. There are many such examples. There are also practice problems (available at a website) at the end of each chapter. It is believed that most, if not all, of the illustrative examples and practice problems are “original”; some have been drawn from National Science Foundation (NSF) workshops/seminars conducted at Manhattan College, and some have been employed for over such a long period of time that the original authors can no longer be identified and properly recognized. If that be the case, please accept the authors’ apologies and be assured that appropriate credit (where applicable) will be given in the next printing.
In constructing this text, topics of interest to all practicing engineers have been included. The organization and contents of the text can be found in the table of contents. The table consists of six main parts—-Introduction to Fluid Flow, Basic Laws, Fluid Transport Classification, Fluid Flow Applications, Fluid-Particle Applications, and Special Topics.
It is hoped that this writing will place in the hands of teachers and students of engineering, plus practicing engineers, a text covering the fundamental principles and applications of fluid flow in a thorough and clear manner. Upon completion of the course, the reader should have acquired not only a working knowledge of the principles of fluid flow, but also experience in their application; and, readers should find themselves approaching advanced texts and the engineering literature with more confidence.
Finally, the authors are particularly indebted to Shannon O’Brien for her extra set of eyes when it came time to proofreading the manuscript.
J. PATRICK ABULENCIALOUIS THEODORE
No one means all he says, and yet very few say all they mean, for words are slippery and thought is viscous.
—Henry Brooks Adams (1837-1918)The Education of Henry Adams
The history of unit operations is interesting. Chemical engineering courses were originally (late 1800 and early 1900s) based on the study of unit processes and/or industrial technologies. However, it soon became apparent that the changes produced in equipment from different industries where similar in nature, i.e., there was a commonality in the fluid flow, heat transfer, and mass transfer operations in the petroleum industry as with the utility industry. These similar operations became known as unit operations.
This book—“Fluid Flow”—was prepared as both a professional book and as an undergraduate text for the study of the principles and fundamentals of the first of the three aforementioned unit operations. Some of the introductory material is presented in the first two parts of the book. Understandably, more extensive coverage is given in the remainder of the book to applications and design. Furthermore, seven additional topics were included in the last part of the book—special topics. These topics are now all required by ABET (Accreditation Board for Engineering and Technology) to be emphasized in course offerings: each of these seven topics is briefly discussed below.
The first chapter in Part VI addresses environmental concerns; nearly one third of undergraduates chose environmental careers. The second topic is health, safety, and accident prevention; new and existing processes today require ongoing analyze in these areas. To better acquaint the student with human relations, engineering and environmental ethics is the third topic. Numerical methods are the next topic encountered since computers are not only used to design multi-component distillation columns but also routinely used in the work force. The success or failure of any business related activity is tied to economics and finance, and this too receives treatment. The “hot” topic—Biomedical Applications—receives treatment in Chapter 33. Finally, open-ended problems (problems that can have more than one solution), are treated in the last chapter. This final chapter requires the reader to ask questions, not always accept things at face value, and select a methodology that will yield the most effective and efficient solution. Illustrative examples on each of these topics are included within each chapter.
Although not a complete treatment of the subject, the text has attempted to present theory, principles, and applications of unit operation in a manner that will benefit the reader and/or prospective engineer in their career as a practicing engineer. Those desiring more information on these topics should proceed to specialized texts in these areas.
This book is the result of several years of effort by the Chemical Engineering Department at Manhattan College. The first rough draft was prepared during the 2001-2002 academic year and underwent peripheral classroom testing during the ensuing years; the manuscript underwent significant revisions during this past year, some of it based on the experiences gained from class testing.
In the final analysis, the problem of what to include and what to omit was particularly difficult. However, every attempt was made to offer engineering course material to individuals at a level that should enable them to better cope with some of the problems they will later encounter in practice. As such, the book was not written for the student planning to pursue advanced degrees; rather, it was primarily written for those individuals who are currently working as practicing engineers or plan to work as engineers in the future solving real world problems.
The entire book can be covered in a three-credit course. At Manhattan, Fluid Flow is taught in the second semester of the sophomore year (Heat and Mass Transfer are taught in the junior year). Finally, it should be again noted that the Manhattan approach is to place more emphasis on the macroscopic approach; however, some microscopic material is included.
INTRODUCTION TO FLUID FLOW
This first part of the book provides an introduction to fluid flow. It contains six chapters and each serves a unique purpose in an attempt to treat important introductory aspects of fluid flow. From a practical point-of-view, systems and plants move liquids and gases from one point to another; hence, the student and/or practicing engineer is concerned with several key topics in this area. These receive some measure of treatment in the six chapters contained in this part. A brief discussion of each chapter follows.
Chapter 1 provides an overview of the History of Chemical Engineering—Fluid Flow. Chapter 2 is concerned with Units and Dimensional Analysis. Chapter 3 introduces Key Terms and Definitions. Chapter 4 provides a discussion of Transport Phenomena versus Unit Operations. The final two chapters introduce the reader to Newtonian Fluids (Chapter 5) and Non-Newtonian Flow (Chapter 6). These subjects are important in developing an understanding of the various fluid flow equipment and operations plus their design, which is discussed later in the text.
HISTORY OF CHEMICAL ENGINEERING—FLUID FLOW
Although the chemical engineering profession is usually thought to have originated shortly before 1900, many of the processes associated with this discipline were developed in antiquity. For example, filtration operations (see Chapter 27) were carried out 5000 years ago by the Egyptians. During this period, chemical engineering evolved from a mixture of craft, mysticism, incorrect theories, and empirical guesses.
In a very real sense, the chemical industry dates back to prehistoric times when people first attempted to control and modify their environment. The chemical industry developed as any other trade or craft. With little knowledge of chemical science and no means of chemical analysis, the earliest “chemical engineers” had to rely on previous art and superstition. As one would imagine, progress was slow. This changed with time. The chemical industry in the world today is a sprawling complex of raw-material sources, manufacturing plants, and distribution facilities which supplies society with thousands of chemical products, most of which were unknown over a century ago. In the latter half of the nineteenth century, an increased demand arose for engineers trained in the fundamentals of chemical processes. This demand was ultimately met by chemical engineers.
1.2 FLUID FLOW
With respect to fluid flow, the history of pipes and fittings dates back to the Roman Empire. The ingenious “engineers” of that time came up with a solution for supplying the never-ending demand for fresh water to a city and then disposing of the wastewater produced by the Romans. Their system was based on pipes made out of wood and stone and the driving force of the water was gravity.(1) Over time, many improvements have been made to the piping system. These improvements have included the material choice, shape and size of the pipes; pipes are now made from different metals, plastic, and even glass, with different diameters and wall thicknesses. The next challenge was the connection of the pipes and that was accomplished with fittings. Changes in piping design ultimately resulted from the evolving industrial demands for specific requirements and the properties of fluids that needed to be transported.
The first pump can be traced back to 3000 B.C. in Mesopotamia. It was used to supply water to the crops in the Nile River valley.(2) The pump was a long lever with a weight on one side and a bucket on the other. The use of this first pump became popular in the Middle East and this technology was used for the next 2000 years. Sometimes, a series of pumps would be put in place to provide a constant flow of water to the crops far from the source. Another ancient pump was the bucket chain, a continuous loop of buckets that passed over a pulley-wheel; it is believed that this pump was used to irrigate the Hanging Gardens of Babylon around 600 B.C.(2) The most famous of these early pumps is the Archimedean screw. The pump was invented by the famous Greek mathematician and inventor Archimedes (287-212 B.C.). The pump was made of a metal pipe in which a helix-shaped screw was used to draw water upward as the screw turned. Modern force pumps were adapted from an ancient pump that featured a cylinder with a piston “at the top that create[d] a vacuum and [drew] water upward.”(2) The first force pump was designed by Ctesibus of Alexandria, Egypt. Leonardo Da Vinci (1452-1519) was the first to come up with the idea of lifting water by means of centrifugal force; however, the operation of the centrifugal pump was first described scientifically by the French physicist Denis Papin (1647-1714) in 1687.(3) In 1754, Leonhard Euler further developed the principles on which centrifugal pumps operate and today the ideal pump performance term, “Euler head,” is named after him.(4) In the United States, the first centrifugal pump to be manufactured was by the Massachusetts Pump Factory. James Stuart built the first multi-stage centrifugal pump in 1849.(3)
1.3 CHEMICAL ENGINEERING
The first attempt to organize the principles of chemical processing and to clarify the professional area of chemical engineering was made in England by George E. Davis. In 1880, he organized a Society of Chemical Engineers and gave a series of lectures in 1887, which were later expanded and published in 1901 as “A Handbook of Chemical Engineering.” In 1888, the first course in chemical engineering in the
United States was organized at the Massachusetts Institute of Technology by Lewis M. Norton, a professor of industrial chemistry. The course applied aspects of chemistry and mechanical engineering to chemical processes.(5)
Chemical engineering began to gain professional acceptance in the early years of the twentieth century. The American Chemical Society was founded in 1876 and, in 1908, it organized a Division of Industrial Chemists and Chemical Engineers while authorizing the publication of the Journal of Industrial and Engineering Chemistry. Also in 1908, a group of prominent chemical engineers met in Philadelphia and founded the American Institute of Chemical Engineers.(5)
The mold for what is now called chemical engineering was fashioned at the 1922 meeting of the American Institute of Chemical Engineers when A. D. Little’s committee presented its report on chemical engineering education. The 1922 meeting marked the official endorsement of the unit operations concept and saw the approval of a “declaration of independence” for the profession.(5) A key component of this report included the following:
“Any chemical process, on whatever scale conducted, may be resolved into a coordinated series of what may be termed ‘unit operations,’ as pulverizing, mixing, heating, roasting, absorbing, precipitation, crystallizing, filtering, dissolving, and so on. The number of these basic unit operations is not very large and relatively few of them are involved in any particular process … An ability to cope broadly and adequately with the demands of this (the chemical engineer’s) profession can be attained only through the analysis of processes into the unit actions as they are carried out on the commercial scale under the conditions imposed by practice.”
The key unit operations were ultimately reduced to three: Fluid Flow (the subject title of this text), Heat Transfer, and Mass Transfer. The Little report also went on to state that:
“Chemical Engineering, as distinguished from the aggregate number of subjects comprised in courses of that name, is not a composite of chemistry and mechanical and civil engineering, but is itself a branch of engineering,…”
A time line diagram of the history of chemical engineering between the profession’s founding to the present day is shown in Fig. 1.1.(5) As can be seen from the time line, the profession has reached a crossroads regarding the future education/curriculum for chemical engineers. This is highlighted by the differences of Transport Phenomena and Unit Operations, a topic that is discussed in Chapter 4.
Figure 1.1 Chemical engineering time-line.
11. http://www.unrv.com/culture/roman-aqueducts.php, 2004.
3. A. H. Church and J. Lal, “Centrifugal Pumps and Blowers,” John Wiley & Sons Inc., Hoboken, NJ, 1973.
4. R. D. Flack, “Fundamentals of Jet Propulsion with Applications,” Cambridge University Press, New York, 2005.
5. N. Serino, “2005 Chemical Engineering 125th Year Anniversary Calendar,” term project, submitted to L. Theodore, 2004.
TRANSPORT PHENOMENA VERSUS UNIT OPERATIONS
As indicated in Chapter 1, chemical engineering courses were originally based on the study of unit processes and/or industrial technologies. It soon became apparent that the changes produced in equipment from different industries were similar in nature; i.e., there was a commonality in the fluid flow operations in the petroleum industry as with the utility industry. These similar operations became known as Unit Operations. This approach to chemical engineering was promulgated in the Little report as discussed earlier in Chapter 1 and to varying degrees and emphasis, has dominated the profession to this day.
The Unit Operations approach was adopted by the profession soon after its inception. During many years (since 1880) that the profession has been in existence as a branch of engineering, society’s needs have changed tremendously and, in turn, so has chemical engineering.
The teaching of Unit Operations at the undergraduate level remained relatively static since the publication of several early-to-mid 1900 texts. However, by the middle of the 20th century, there was a slow movement from the unit operation concept to a more theoretical treatment called transport phenomena. The focal point of this science was the rigorous mathematical description of all physical rate processes in terms of mass, heat, or momentum crossing boundaries. This approach took hold of the education/curriculum of the profession with the publication of the first edition of the Bird et al. book.(1) Some, including both authors of this text, feel that this concept set the profession back several decades since graduating chemical engineers, in terms of training, were more applied physicists that traditional chemical engineers.
There has fortunately been a return to the traditional approach of chemical engineering in recent years, primarily due to the efforts of the Accreditation Board for Engineering Technology (ABET). Detractors to this approach argue that this type of practical education experience provides the answers to ‘what’ and ‘how’, but not ‘why’ (i.e., a greater understanding of both physical and chemical processes). However, the reality is that nearly all practicing engineers (including chemical engineers) are in no way presently involved with the ‘why’ questions; material normally covered here has been replaced, in part, with a new emphasis on solving design and open-ended problems. This approach is emphasized in this text.
4.2 THE DIFFERENCES
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