ME 321: Engineering Thermodynamics

ME 323: Heat Transfer Winter 2018 Portland State University Maseeh College of Engineering and Computer Science TuTh: 10:00am-11:50am

Course Objectives To provide engineering students with the basic knowledge and the fundamental understanding of Heat Transfer: conduction, convection, radiation, and combinations of each. The methods for solving many problems of practical interest to the design engineer are discussed by way of applied mathematics and empirical correlations.

Instructor Derek Tretheway Associate Professor Department of Mechanical and Materials Engineering EB 402H Phone: 725-8760 Email: [email protected] Office hours: Monday 2:00-3:00 pm, Tuesday 2:00-3:00 pm, and by appointment (note, at any time, if my office door is open, I may be able to answer questions. If I don’t have time at that moment, I will arrange a time to meet with you.)

Teaching Assistants/Grader Naveen Weerasekera, EB 301-10, office hours Mondays 3-5pm.

Prerequisites: Math 256, ME 321, ME 320

Textbook: Bergman and Lavine, Fundamentals of Heat and Mass Transfer, 8th Edition, John Wiley and Sons 2017.

Note: older editions of the text may be used. I will assign homework problems out of the 8th edition and post the problem statements on my website.

Policies There will be two, no longer than thirty minute in-class quizzes. The midterm examine will last one class period. The final exam will be comprehensive. All quizzes and exams are mandatory. Discuss any potential conflicts well before the exam dates. Quiz dates TBA in prior lecture. There will be no make-up quizzes or exams.

If you have a disability, are registered with the Disability Resource Center, and are in need of academic accommodations, please notify me (D. Tretheway) immediately to arrange needed supports. If you are unregistered or need information about disabilities, please contact the Disability Resource Center on campus at 725-4150. Cumulative grades will be based on the following weights

Homework 20% assigned/collected on Thursday Quizzes 10% Midterm Exam 30% Final Exam 40% (March 20th, 10:15am-12:05pm)

ME323 Homework Format:

1. Name and date in upper right hand corner on every page. Please staple pages together. 2. Homework assignment number on upper left. 3. Please write legibly in dark pencil or pen. Print (no cursive) with decent size. 4. Identify each problem clearly. 5. Please box the results using proper significant digits and show the units. 6. State the problem (what’s given). 7. State the required results. 8. List the assumptions employed – only state the assumptions that can potentially cause the answer to differ significantly from the real answer. 9. In the analysis, clearly identify what you are doing. Do not string together formulas without connecting them properly with explanation text. Justify the use of formulas. 10. Add comments to results when appropriate. Do the results appear reasonable? Are the assumptions reasonable? Is there additional relevant material not reflected in the analysis? Learning Objectives

At the end of the term, students taking ME323 should know

1. Heat Transfer Basics a. Modes of heat transfer: conduction, convection, radiation b. Mechanisms of each mode c. General quantitative behavior in each mode d. Resistor analogy for all three e. Conductive and convective heat resistance f. Identify 2-D heat conduction and apply appropriate resistance model

2. Heat Transfer From Fins a. Conduction along fin, simplified governing eqns. b. Limitations of solutions c. Heat transfer coefficients d. Proper boundary conditions e. Exact solution tables

3. Transient Heat Conduction a. General method b. Bi<0.1, Bi>.1, Fo>.2: approximate analytic solutions c. Cartesian, cylindrical, spherical coordinates d. Meaning of Bi and Fo e. Numerical methods/terminology

4. Forced Convection a. Meaning of Nu, Pr, Re b. External flow i. Momentum and thermal boundary layers, laminar/turbulent flows ii. ReL, NuL, Cfl c. Internal flow i. Momentum and thermal boundary layers, entrance lengths, fully developed flow ii. Exact solutions for Nu (laminar flow, Ts=constant, qs=constant) iii. Application of empirical correlations iv. Film temperature

5. Natural Convection a. Meaning of Gr, Ra, , Pr b. General understanding of mechanism, velocity, and temperature profiles c. General solution procedures: guess T, compute hnat and iterate, (laminar exact, others correlations)

6. Heat Exchange Design a. Log mean temperature difference b. Co-flow/counter-flow designs c. Compact heat exchangers and performance metrics

7. Radiation a. Spectrum of radiation and emissive power b. Blackbody, graybody, surface properties c. Impact of emissivity, absorptivity, reflectivity, transmissivity d. Shape factors and view factors

8. Mixed Heat Transfer a. Understand general approach to simultaneous conduction, convection, and radiation ME323 Course Outline (tentative*)

Class Date Subject Reading

1 1/9 Introduction: Why we’re here. Ch. 1 2 1/11 Overview: conduction, convection, radiation Ch. 1 3 1/16 No class 4 1/18 Conduction: derivation of Heat Eqn, BCs Ch. 2 5 1/23 Conduction: derivation of Heat Eqn, BCs cont. Ch. 2/3 6 1/25 1-D steady state conduction/HT from extended surfaces Ch. 3 7 1/30 2-D steady state heat conduction Ch. 4 8 2/1 Transient heat conduction: lumped capacitance, Bi Ch. 5 9 2/6 Fundamentals of convection Ch. 6 10 2/8 Forced convection: external flows Ch. 7 11 2/13 Midterm Exam 12 2/15 Forced convection: internal flow Ch. 8 13 2/20 Natural convection (free convection) Ch. 9 14 2/22 Heat Transfer with Phase changes Ch. 10 15 2/27 Heat exchangers Ch. 11 16 3/1 Heat exchanger analysis 17 3/6 Radiation fundamentals Ch. 12 18 3/8 Blackbody/Graybody radiation 19 3/13 Radiation exchange Ch. 13 20 3/15 Additional topics, Review

* note: This is a tentative course outline. Lecture topics and reading assignments may vary depending on lecture progress. The midterm date may change! The date will be confirmed by an announcement in lecture. Do not claim that you missed the midterm exam because it did not occur at the date implied by this outline!