Chemical Engineering 340

TRANSPORT PROCESSES II (Heat Transfer)

Course Outline

1. Conduction Basics

- Types of heat transfer processes (conduction, convection, radiation)

- Thermal conductivity (liquids, solids and gases)

- Energy balance

- Surface energy balance

- Heat diffusion equation

- Boundary and initial conditions

- One-dimensional steady-state conduction (including radial systems and sphere): Temperature distribution, thermal resistance (Composite Wall), contact resistance, conduction with thermal energy generation

- Two-dimensional steady state conduction

2. Heat Transfer From Extended Surfaces

- General form of the energy equation (1D)

- Straight fins of uniform cross-sectional area

Boundary conditions

Temperature distribution

Fin heat transfer rate

- Common fin shapes

Efficiency and effectiveness

Fin resistance

- 2D Mathematical/numerical models

Finite-difference equation (Nodal network, finite-difference form of heat equation, nodal energy balance)

3. Transient Conduction

- Significant dimensionless numbers for transient conduction problems

Biot Number (Bi), Fourier Number (Fo)

- Lumped capacitance method

Transient temperature response and critical response time

- Spatial Effects

1D heat equations: initial condition, two boundary conditions

- Transient heat conduction in various geometries

Plane wall with convection

Radial systems with convection

The semi-infinite solid

Heisler Charts

Temperature distribution

Fin heat transfer rate

- Transient

Boundary conditions

4. Convection

- Boundary Layer Theory (external flow, internal flow)

Local heat flux, local and average convection coefficient

Convective boundary layer (velocity, thermal, laminar, turbulent, mixed)

Boundary layer similarity parameters (Prandtl (Pr), Reynolds (Re) and Nusselt (Nu) numbers)

Similarity boundary layer solution

- Boundary layer separation (cylindrical and non-cylindrical objects in cross-flow)

- Flow across banks and tubes

- Internal flow: thermodynamic entry length, mean temperature (differential form), Nusselt number in entrance regime and fully developed flow regime

- Free Convection

Laminar free convection on a vertical surface

Similarity considerations (introduce Grashof number, Rayleigh (Ra) number)

Plate orientation and averaged Nusselt numbers

5. Boiling and Condensation

- Boiling Modes

- Pool Boiling

- Forced-convection Boiling

- Condensation

6. Heat Exchangers

- Heat exchanger types

Double-pipe exchanger, shell-and-tube exchanger

- Heat exchanger analysis

Parallel- and counter-flow exchanger

Shell-and-tube exchangers, parallel- and counter-flow

Effectiveness (NTU Relations)

7. Radiation

- Fundamental Concepts

Intensity, Blackbody radiation, surface emission, absorption, reflection, and transmission, Kirchhoff's law

- Environmental Radiation