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P R E FA C E

This sixth edition of the text on the unit operations of chemical engineering has been extensively revised and updated, with much new material and considerable condensation of some sections. Its basic structure and general level of treatment, however, remain unchanged. It is an introductory text, written for undergraduate students in their junior or senior years who have completedthe usual courses in mathematics, physics, chemistry, and an introduction to chemical engineering. An elementary knowledge of material and energy balances and of thermodynamic principles is assumed. Separate chapters are devoted to each of the principal unit operations, grouped into four sections: fluid mechanics, heat transfer, mass transfer and equilibrium stages, and operations involvingparticulate solids. One-semester or one-quarter courses may be based on any of these sections or combinations of them. The order of the first 16 chapters has not been changed; later ones, dealing with mass transfer and operations involving solids, have been rearranged in a more logical order. Nearly all equations have been written for SI units, and the Newton’s law conversion factor gc has beeneliminated except in the few instances where it must be included. Symbols for dimensionless groups have been changed to Re for NRe, for example, Pr for NPr, and so forth. Many new examples and problems have been added, some reflecting the importance of biochemical engineering processes. Material on handling, mixing, and grinding particulate solids has been greatly condensed and dealt with in a singlechapter. The number of appendixes is reduced from 22 to 19. Derivations of the differential equations for continuity and momentum balances, leading to the Navier-Stokes equation, have been added, as well as the differential forms of Fourier’s law and Fick’s law, emphasizing the analogies among momentum, heat, and mass transfer. The chapter on adsorption has been expanded to include new material onchromatography and ion exchange, and renamed “Fixedbed Separations.” Other new material has been added on viscoelastic fluids, laminar flow in annuli, drag coefficients, affinity laws for pumps, high-efficiency agitators and motionless mixers, plate-type heat exchangers, boiling by submerged tube bundles, cooling towers, aqueous phase extraction, cross-flow filtration, and many other topics. Many of theproblems at the ends of the chapters are new or revised. Most are expressed in SI units. Nearly all the problems can be solved with the aid of a pocket calculator; for a few, a computer solution is preferable. McGraw-Hill and the authors thank Dr. N. T. Obot for his many suggestions regarding fluid mechanics and heat transfer, and Professor Charles H. Gooding of Clemson University for his detailed andhelpful review of the manuscript.
Julian C. Smith Peter Harriott
xvii

iii

CONTENTS

Preface

xvii

SECTION I

Introduction
Definitions and Principles
Unit Operations Unit Systems
Physical Quantities / SI Units / CGS Units / Gas Constant / FPS Engineering Units / Conversion of Units / Units and Equations 3 4 4

1

Dimensional Analysis Basic Concepts
Equations of State ofGases

16 20 24 25 27

Symbols Problems References

SECTION II

Fluid Mechanics
Fluid Statics and Its Applications
Hydrostatic Equilibrium Applications of Fluid Statics Symbols Problems References
31 32 34 41 42 43 44 45 46 51 59 63 64 65 vii

2

3

Fluid Flow Phenomena
Laminar Flow, Shear Rate, and Shear Stress Rheological Properties of Fluids Turbulence Boundary Layers SymbolsProblems References

viii

CONTENTS

4

Basic Equations of Fluid Flow
Mass Balance in a Flowing Fluid; Continuity Differential Momentum Balance; Equations of Motion Macroscopic Momentum Balances Mechanical Energy Equation Symbols Problems References

67 67 72 77 82 90 92 93 94 94 97 104 117 123 124 127 128 128 133 134 140 145 147 148 149 150 150 157 162 171 182 183 185 187 187 194...
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