ChE 353 Transport Phenomena

ChE 353 . . Transport Phenomena

The objective of this course is to enable the student, through practice and study, to become a competent user of the equations and principles of Transport Phenomena. The student should develop a physical understanding of momentum, heat, and mass transfer as well as see the applicability of the material covered in Math 408 and 427K. The knowledge gained will be useful to you in future courses (ChE 354, 353M, 363, 372) and future employment.

Prior to beginning this course, the student should have a mastery of the following topics:

Force balances and Newton's equation of motion (Physics 303).

Steady-state macroscopic mass and energy balances (ChE 317).

Algebra, trigonometric functions, geometry, coordinate systems (Cartesian, cylindrical, and spherical), calculation of areas & volumes of simple shapes, differentiation, integration (including integration by parts and trigonometric substitutions), natural log and exponential functions, solutions of simple first order and second order ordinary differential equations, Fourier series, and solution of partial differential equations by separation of variables (Math 408 & 427K).

Professor: D.R. Lloyd

Office Hours: To discuss conceptual difficulties: CPE 3.422. T, Th 13:00–14:30

Text: "Transport Phenomena, 2^nd Edition" by Bird, Stewart & Lightfoot. Bring your book with you to every class and recitation session. The following material is to be covered :

App. A, Chapters 1, 9, 17; 2, 10, 18; 3, 11, 19; 4, 12, 20; 5, 13, 21; 6, 14, 22, 7; 15, 23.

You are expected to read the assigned material prior to class.

Lectures: T,Th 9:30–11:00 in CPE 2.218. Please be punctual. Attendance is not compulsory, but is strongly recommended (see Quizzes below.) Most lectures will be based on reading assignments that you must complete prior to coming to class. You will be asked questions based on that assignment.

Homework: As each topic is covered in class, recommended practice problems will be assigned. It is imperative that you learn how to solve these problems in preparation for quizzes and tests. These practice problems will not be collected for grading; however, the answers to these questions will be given when the problems are assigned. If you do not get the correct answers, you need to visit the TA during the office hours posted above and attend the recitation sessions.

Recitation Sessions: Wednesday 14:00–16:00 (#12370 & #12375) in CPE 2.218. Please be punctual. Attendance is not compulsory, but is strongly recommended (see Quizzes below.) Most of the session will be used to discuss the suggested practice problems.

Quizzes: There will be approximately ten unannounced quizzes of one or two questions each held during some classes and some recitation sessions. Most of the quizzes will be done without the aid of your text book. Any tables and most equations that are considered necessary for solving the problem will be distributed with the quiz. The quizzes will be based on material covered in reading assignments, classroom discussions, and suggested practice problems. You have one week after the quiz is returned to you to request re-grading. All quizzes count (see Grading Scheme below.)

Tests: Three tests are scheduled for 19:00–22:00 on Monday 24 September, 29 October, and 3 December in CPE 2.218. Most of the tests will be done without the aid of your text book. Any tables and most equations that are considered necessary for solving the problem will be distributed with the test. You have one week (after the test is returned to you) to request re-grading. All tests count towards your final grade (see Grading Scheme below.)

Final Exam: Optional (see below). Wednesday 12 December 9:00–12:00

Grading Scheme: The total number of points from the quizzes and tests will be added to determine your final score at the end of the semester. Quizzes will represent approximately 30% of the total. Tests will represent approximately 70% of the total. On the last class day you will be told your final score and the corresponding letter grade {You need C or better to advance to ChE 353M & 354.} On the last class day you will have the option of accepting the letter grade earned to that point – or – multiplying your current percentage score by 0.9 and taking a final exam worth 10%. If you do not come to the last class, one of the two options will be selected for you. Electing to take the final exam, and then not showing up will result in a drop of one letter grade.

Course / Instructor Evaluation will be done during the last week of classes.

The University of Texas at Austin provides upon request appropriate academic adjustments for qualified students with disabilities. For information contact the Office of the Dean of Students at 471-6259, 471-4241 TDD or the College of Engineering Director of Students with Disabilities at 471-4382.

THE APPLICATION OF TRANSPORT PHENOMENA

INTRODUCTION

Many similarities exist in the manner in which materials are modified or processed into final products in the chemical, biological, pharmaceutical, food, and microelectronic industries. These seemingly different chemical, physical, or biological processes can be considered as a series of separate and distinct processing steps called unit operations.

In ChE 354 and 363 you will learn about the application of many of these unit operations in a variety of industries. For example, the unit operation distillation is used to purify or separate alcohol in the beverage industry and hydrocarbons in the petroleum industry. Drying of grain and other foods is similar to the drying of lumber, filtered precipitates, and rayon yarn. The unit operation absorption occurs in the transfer of oxygen from air to the reaction medium in a fermentation process or in a sewage treatment plant; absorption also occurs when hydrogen gas is transferred to a liquid for the hydrogenation of oil. Evaporation of salt solutions to produce pure water in the chemical industry and in the production of drinking water is similar to the evaporation process used to produce concentrated fruit juices in the food industry. Settling and sedimentation of suspended solids in sewage treatment and in the mining industry are similar. Movement of liquid hydrocarbons in a petroleum refinery and flow of milk in a dairy plant are carried out in a similar fashion.

Unit operations deal mainly with the transfer of energy, mass, and momentum. By doing so, these unit operations transfer and change materials by physical-chemical and physical means.

CLASSIFICATION OF UNIT OPERATIONS

1. Fluid flow operations are concerned with the movement or transportation of any fluid from one point to another. The principles of momentum transfer studied in ChE 353 govern this movement.

2. Heat transfer operations are concerned with the movement or transportation of heat from one point to another. The principles of heat transfer studied in ChE 353 govern this movement.

3. Evaporation. This process, which combines mass and heat transfer, deals with the evaporation of a volatile solvent (such as water) from a nonvolatile solute (such as salt or any other material in solution.)

4. Drying. In this mass transfer operation volatile liquids, usually water, are removed from solid materials.

5. Distillation. This is a mass transfer operation whereby components of a liquid mixture are separated by boiling (and thus heat transfer is involved) because of their differences in vapor pressure.

6. Absorption. In this mass transfer process a component is removed from a gas stream by treatment with a liquid.

7. Membrane separations involves the diffusion of a solute from a liquid or gas through a semipermeable membrane barrier to another fluid.

8. Liquid–liquid extraction. In this unit operation a solute in a liquid solution is removed by contacting with another liquid solvent that is relatively immiscible with the solution. Thus, this process involves fluid flow or momentum transfer and mass transfer.

9. Liquid–solid leaching involves treating a finely divided solid with a liquid that dissolves out and removes a solute contained in the solid. Consequently, diffusion in solids and liquids must be considered.

10. Crystallization concerns the removal of a solute, such as a salt, from a solution by precipitating the solute from the solution.

11. Mechanical–physical separations such as filtration and settling involve the principles of momentum transfer.

Notice that many of these unit operations have certain fundamental and basic principles or mechanisms in common. For example, diffusion or mass transfer occurs in drying, absorption, distillation, and crystallization. Heat transfer occurs in drying, distillation, and evaporation. In all processes fluid is flowing, which causes momentum transfer. Hence, we study the fundamentals of the various transfer or transport processes in ChE 353 to prepare you for ChE 353M, 354, and 363.

The fundamentals of transport phenomena will also be used in your reaction kinetics / reactor design course ChE 372.

ChE 353 will also provide you with the opportunity to apply the skills you developed in Mass & Energy Balances, Calculus 1, Calculus 2, and Differential Equations.

Text Box:

D.R. Lloyd