BME303S

Unit Description and General Aims

The objective in presenting this unit is to provide students with detailed knowledge of heat and mass transfer concepts.

The subject matter covered in this unit will include: an introduction to the fundamental principles and basic laws governing conduction, convection, and radiation heat transfer; heat flow mechanisms; an examination of how fins are designed for maximum efficiency; and, transient temperature charts.

Students will also be instructed on: boundary layer concepts; distinguishing between the physical mechanisms concerning natural and forced convection; dimensional analysis as applied to convection; the basic steps in specifying heat exchanger requirements, selecting an appropriate type for a particular application, and employing LMTD and NTU methods of heat exchanger analysis; drawing analogies between heat and mass transfer mechanisms; and, examining diffusion and convective mass transfer principles in detail.

Project work involving the different aspects of the design and selection of fins, and heat exchangers will also be a component of the unit requirements.

At the conclusion of this unit, students will have been imparted with the requisite knowledge to undertake work utilizing heat and mass transfer concepts such as designing and analysing heat transfer equipment, and specifying and selecting heat exchangers for various applications.

Learning Outcomes

On successful completion of this Unit, students are expected to be able to:

1. Demonstrate knowledge of heat and mass transfer mechanisms and principles.
   Bloom's Level 2
2. Define and solve steady-state and transient conduction problems.
   Bloom's Level 3
3. Design and analysis heat transfer equipment.
   Bloom's Level 6
4. Determine the basic relations in boundary layers.
   Bloom's Level 5
5. Distinguish between natural and forced convection mechanisms.
   Bloom's Level 4
6. Derive heat transfer correlations in two-phase heat transfer.
   Bloom's Level 4
7. Specify and select heat exchangers for various applications.
   Bloom's Level 5

Student assessment

Prescribed and Recommended Readings

Textbook

Holman, J 2009, Heat Transfer, 10th edn, McGraw-Hill Education, ISBN: 978-0073529363

Cengel, YA 2005, Heat Transfer: A Practical Approach, 2nd edn, Tata Mcgraw-Hill, ISBN: 9780070594173

Reference

Bergman, TL, Incropera, FP & Lavine, AS 2011, Fundamentals of Heat and Mass Transfer, 7th edn, John Wiley & Sons, ISBN: 9780470501979

Ozisik, MN 1985, Heat Transfer: A Basic Approach, illustrated, McGraw-Hill, ISBN: 9780070664609

Kreith, F, Manglik, R & Bohn, M 2010, Principles of Heat Transfer, 7th edn (revised), Cengage Learning, 2010, ISBN: 9780495667704

Nag, PK 2011, Heat And Mass Transfer, 3rd edn, Tata McGraw-Hill Education, ISBN: 978-0070702530

Journal, website

www.sciencedirect.com/science/journal/00179310

Notes and Reference Texts

Knovel library: http://app.knovel.com
IDC Technologies
Other material advised during the lectures

Unit Content

Topic 1

Introductory Concepts

1. Modes of heat transfer
2. Basic laws governing conduction, convection, and radiation heat transfer
3. Thermal conductivity
4. Fourier’s, Newton’s, and Stefan Boltzmann’s Law
5. The convective heat transfer coefficient
6. Radiation heat transfer
7. Combined heat transfer mechanism
8. Boundary conditions

Topics 2 and 3

Conduction

1. Thermal conductivity of solids, liquids, and gases
2. Factors influencing conductivity measurement
3. General differential equation of conduction
4. One dimensional steady state conduction
5. Linear heat flow through a plane and composite wall, tube, and sphere
6. Critical thickness of insulation
7. Effect of variable thermal conductivity
8. Conduction with heat generation in slabs, cylinders, and spheres
9. Conduction in solids with negligible internal temperature gradient (lumped system analysis)
10. Use of transient temperature charts (Heisler’s charts) for transient conduction in slabs, long cylinders, and spheres
11. Use of transient temperature charts for transient conduction in semi-infinite solids

Topic 4

Fins

1. Conduction convection system
2. Extended surfaces – rectangular, triangular, circumferential, and pin fins
3. Conduction analysis
4. Fins of uniform and non-uniform cross-sectional area
5. Heat dissipated by fins
6. Effectiveness and efficiency of fins
7. Design of fins for maximum heat transfer

Topic 5

Concepts and Basic Relations in Boundary Layers

1. Flow over a body velocity boundary layer
2. Critical Reynold’s Number
3. Drag coefficient and drag force
4. Thermal boundary layer
5. General expression for local heat transfer coefficient
6. Average heat transfer coefficient
7. Flow inside a duct-velocity boundary layer

Topic 6

Natural and Forced Convection

1. Physical mechanism of natural convection
2. Application of dimensional analysis for natural convection
3. Grashoff number
4. Empirical relationship for natural convection
5. Physical mechanism of forced convection
6. Application of dimensional analysis for forced convection
7. Physical significance of Reynold’s, Prandtl, Nusselt, and Stanton numbers
8. Flow over plates, flow across cylinders and spheres and flow in tubes

Topic 7

Two-Phase Heat Transfer

1. Boiling heat transfer
2. Pool boiling
3. Boiling regimes and boiling curve
4. Pool boiling correlations
5. Condensation heat transfer
6. Film condensation
7. Derivation of average heat transfer coefficient for laminar film condensation over vertical plate
8. Heat transfer correlations for inclined plates, vertical tubes, horizontal bank tubes

Topic 8

Heat Exchangers

1. Heat exchanger classification
2. Heat exchanger performance
3. Heat exchanger transfer units
4. Overall heat transfer coefficient
5. Fouling and fouling factor
6. LMTD, NTU methods of analysis of heat exchangers

Topics 9 and 10

Radiation Heat Transfer

1. Introduction
2. Absorption and reflection of radiant energy
3. Emission, radiosity and irradiation
4. Black and non-black bodies
5. Stefan-Boltzmann’s Law, Kirchhoff’s Law, Planck’s Law, and Wein’s Displacement Law
6. Radiation heat exchange between two parallel infinite black surfaces
7. Radiation heat exchange between two parallel infinite grey surfaces
8. Non-luminous gas radiation
9. Intensity of radiation and solid angle
10. Effect of radiation shield
11. Lambert’s law; radiation heat exchange between two finite surfaces – configuration factor

Topic 11

Mass Transfer

1. Mass and mole concentrations
2. Molecular diffusion
3. Eddy diffusion
4. Molecular diffusion from an evaporating fluid surface
5. Convective mass transfer
6. Wet and dry bulb thermometer

Topic 12

Unit Review

In the final week, students will have an opportunity to review the contents covered so far. Opportunity will be provided for a review of student work and to clarify any outstanding issues. Instructors/facilitators may choose to cover a specialized topic if applicable to that cohort.

Software/Hardware Used

Software

• Software: Interactive Heat Transfer software
• Version: 4.0
• Instructions:  Download link http://bcs.wiley.com/he-bcs/Books?action=resource&bcsId=6563&itemId=0470501979&resourceId=25674
• Additional resources or files: N/A

Hardware

• PC/Laptop