Preface

The title of this text has been changed from Transport Processes and Unit Operations to Transport Processes and Separation Process Principles (Includes Unit Operations). This was done because the term "unit operations" has been largely superseded by the term "separation processes," which better reflects the modern nomenclature being used.

In this fourth edition, the main objectives and the format of the third edition remain the same. The sections on momentum transfer have been greatly expanded, especially the sections on fluidized beds, flow meters, mixing, and non-Newtonian fluids. Material has been added to the chapters on mass transfer. The chapters on absorption, distillation, and liquid-liquid extraction have also been enlarged. More new material has been added to the sections on ion exchange and crystallization. The chapter on membrane separation processes has been greatly expanded, especially for gas-membrane theory.

The field of chemical engineering involved with physical and physical-chemical changes of inorganic and organic materials and, to some extent, biological materials is overlapping more and more with the other process-engineering fields of ceramic engineering, process metallurgy, agricultural food engineering, wastewater-treatment (civil) engineering, and bioengineering. The principles of momentum, heat, and mass transport and the separation processes are widely used in these processing fields.

The principles of momentum transfer and heat transfer have been taught to all engineers. The study of mass transfer has been limited primarily to chemical engineers. However, engineers in other fields have become more interested in mass transfer in gases, liquids, and solids.

Since chemical and other engineering students must study so many topics today, a more unified introduction to the transport processes of momentum, heat, and mass transfer and to the applications of separation processes is provided. In this text the principles of the transport processes are covered first, and then the separation processes (unit operations). To accomplish this, the text is divided into two main parts.

PART 1: Transport Processes: Momentum, Heat, and Mass

This part, dealing with fundamental principles, includes the following chapters: 1. Introduction to Engineering Principles and Units; 2. Principles of Momentum Transfer and Overall Balances; 3. Principles of Momentum Transfer and Applications; 4. Principles of Steady-State Heat Transfer; 5. Principles of Unsteady-State Heat Transfer; 6. Principles of Mass Transfer; and 7. Principles of Unsteady-State and Convective Mass Transfer.

PART 2: Separation Process Principles (Includes Unit Operations)

This part, dealing with applications, covers the following separation processes: 8. Evaporation; 9. Drying of Process Materials; 10. Stage and Continuous Gas-Liquid Separation

Processes (humidification, absorption); 11. Vapor-Liquid Separation Processes (distillation); 12. Liquid-Liquid and Fluid-Solid Separation Processes (adsorption, ion exchange, extraction, leaching, crystallization); 13. Membrane Separation Processes (dialysis, gas separation, reverse osmosis, ultrafiltration, microfiltration); 14. Mechanical-Physical Separation Processes (filtration, settling, centrifugal separation, mechanical size reduction).

In Chapter 1 elementary principles of mathematical and graphical methods, laws of chemistry and physics, material balances, and heat balances are reviewed. Many readers, especially chemical engineers, may be familiar with most of these principles and may omit all or parts of this chapter.

A few topics, primarily those concerned with the processing of biological materials, may be omitted at the discretion of the reader or instructor; these include Sections 5.5, 6.4, 8.7, 9.11, and 9.12. Over 240 example or sample problems and over 550 homework problems on all topics are included in the text. Some of the homework problems involve biological systems, for those readers who are especially interested in that area.

This text may be used for a course of study following any of the following five suggested plans. In all plans, Chapter 1 may or may not be included.

1. Study of transport processes of momentum, heat, and mass and separation processes. In this plan, most of the entire text, covering the principles of the transport processes in Part 1 and the separation processes in Part 2, is covered. This plan would be applicable primarily to chemical engineering as well as to other process-engineering fields in a one-and-one-half-year course of study at the junior and/or senior level.

2. Study of transport processes of momentum, heat, and mass and selected separation processes. Only the elementary sections of Part 1 (the principles chapters—2, 3, 4, 5, 6, and 7) are covered, plus selected separation-processes topics in Part 2 applicable to a particular field, in a two-semester or three-quarter course. Students in environmental engineering, food process engineering, and process metallurgy could follow this plan.

3. Study of transport processes of momentum, heat, and mass. The purpose of this plan in a two-quarter or two-semester course is to obtain a basic understanding of the transport processes of momentum, heat, and mass transfer. This involves studying sections of the principles chapters—2, 3, 4, 5, 6, and 7 in Part 1—and omitting Part 2, the applied chapters on separation processes.

4. Study of separations processes. If the reader has had courses in the transport processes of momentum, heat, and mass, Chapters 2-7 can be omitted and only the separation processes chapters in Part 2 studied in a one-semester or two-quarter course. This plan could be used by chemical and certain other engineers.

5. Study of mass transfer. For those such as chemical or mechanical engineers who have had momentum and heat transfer, or those who desire only a background in mass transfer in a one-quarter or one-semester course, Chapters 6, 7, and 10 would be covered. Chapters 9, 11, 12, and 13 might be covered optionally, depending on the needs of the reader.

Different schools and instructors differ on the use of computers in engineering courses. All of the equations and homework problems in this text can be solved by using ordinary hand-held computers. However, more complicated problems involving numerical integration, finite-difference calculations, steady- and unsteady-state two-dimensional diffusion and conduction, and so on, can easily be solved with a computer using spreadsheets. Almost all undergraduate students are proficient in their use.

The SI (Systeme International d'Unites) system of units has been adopted by the scientific community. Because of this, the SI system of units has been adopted in this text for use in the equations, example problems, and homework problems. However, the most important equations derived in the text are also given in a dual set of units, SI and English, when different. Many example and homework problems are also given using English units.

Christie John Geankoplis