Transport Phenomena II
CHBE 351
Dr. Trajano
Heat transfer
Heat is a form of energy and heat transfer is thermal energy in transit
Thermodynamics is about
Interaction of energy with matter
Conversion of heat into mechanical work
We never worry about where
Problem 9.2 Textbook Unsolved
Problem 9.3 Textbook Unsolved
Problem 9.17 Textbook Unsolved
Consider a vertical plate of dimension 0.25 m x 0.50 m that is
at Ts=100oC in a quiescent environment at T=20oC. In the
interest of minimizing heat transfer from th
Example Problem 6.1  Textbook
16
17
Example 6.2  Textbook
18
19
Example 6.3  Textbook
20
21
Problem 6.59 Textbook Unsolved
An object of irregular shape 1 m long at Ts=100oC is suspended in an airstream of
0oC, 1 atm, and a velocity of 120 m/s. The air
Transport Phenomena II
(Heat and Mass Transfer)
Concentric Tube Annulus
Review Problems on Internal Flows
The Concentric Tube Annulus
Fluid passes through the annulus and convection heat transfer may occur
to or from both the inner and outer tube surfaces
Transport Phenomena II
(Heat and Mass Transfer)
Laminar Flow Correlations
Turbulent Flow Correlations
Laminar Flow Correlations
For fullydeveloped laminar flow in a circularsection pipe, partial
differential equations of mass, momentum and energy conse
Transport Phenomena II
(Heat and Mass Transfer)
Energy Balance in Pipe Flow
Constant Heat Flux at the Wall
Constant Surface Temperature
Energy Balance in Pipe Flow
Heat transfer for full length of pipe:
Ein Eout
or
Fluid temperature generally varies
in th
Transport Phenomena II
(Heat and Mass Transfer)
Internal Flow
Velocity Profile in Internal Flow
Temperature Profile in Internal Flow
External and Internal Flow
External Flow
Boundary layer grows
without limit
Flow characterised by
freestream conditions
Transport Phenomena II
(Heat and Mass Transfer)
Heat/Mass Transfer Analogy
Evaporative Cooling
The Reynolds Analogy
Heat/Mass Transfer Analogy
T*(x*,y*=0)=0
T*(x*, y*)=1
C*(x*,y*=0)=0
C*(x*, y*)=1
Normalized equations have the same form therefore the pro
Transport Phenomena II
(Heat and Mass Transfer)
Boundary Layer Analysis
Fundamental Transport Equations
Dimensionless Numbers
Functional Relations
Boundary Layer Analysis
Apply conservation laws to differential control volume in
boundary layer and then ap
Transport Phenomena II
(Heat and Mass Transfer)
Introduction to Convection
Modes of Heat Transfer
Heat transfer is the thermal energy in transit
due to a temperature difference
3 modes of heat transfer:
Conduction: energy is
transferred from atom to at
Transport Phenomena II
(Heat and Mass Transfer)
Conservation of Energy
First Law of Thermodynamics
The Surface Energy Balance
First Law of Thermodynamics
Over a time interval:
The increase in the amount if energy stored in
a control volume must equal th
Transport Phenomena II
(Heat and Mass Transfer)
External Flow
Flow over a Flat Plate
External Flow
Evaluate convection heat transfer problems by
assessing the system geometry and flow conditions and
selecting an appropriate Nu correlation.
Will consider
Engineering Thermodynamics
CHBE 346
Phase diagrams of Nonideal Systems
Concepts for Generalized Phase Equilibria

Explain nonidealities
Explain deviations from Raoults law
Nonideal Systems
Positive deviation from Raoults law (linear which holds for only
Heat and Mass Transfer
CHBE 351
Tutorial 05
Problem 1 (Problem 6.83  Textbook Unsolved)
A disk of 20mm diameter is covered with a water film. Under steadystate
conditions, a heater power of 200 mW is required to maintain the diskwater film
at 305 K in