CHE 3103
Jennings
PROBLEM 10 - 46,
p.699 in Bergman, et al.
Saturated steam at 1 atm condenses on the outer surface of a vertical 100-mmdiameter pipe 1 m long, having a uniform surface temperature of 94 oC. Estimate the
total condensation rate and the hea
CHE 3103
Jennings
PROBLEM 22 - 23,
p.678 in Himmelblau.
On a cold (5 oF) day, 30 gallons per minute of water is being pumped from a well to a
storage tank 100 ft above the level of the water in the well. The temperature of the well
water is 35 oF. Althoug
CHE 3103
PROBLEM 10 - 54,
Jennings
p.699 in Bergman, et al.
The condenser of a steam power plant consists of a square (in-line) array of 625 tubes,
each of 25-mm diameter. Consider conditions for which saturated steam at 0.105 bars
condenses on the outer
CHE 3103
2015
Heat Transfer Processes
Jennings
Spring,
HOMEWORK # 1: Introduction
( due Friday, 1 / 23 )
1.
[Problem 22-Q1, p.653 in Himmelblau.] Answer the following questions true or
false.
a) The law of the conservation of energy says that all of the e
CHE 3103
Jennings
PROBLEM 11 - 17,
p.751 in the text.
A concentric tube heat exchanger of length, L = 2 m, is used to thermally process a
pharmaceutical product flowing at a mean velocity of u C = 0.1 m/s with an inlet
temperature of TCi = 20 oC. The inne
CHE 3103
PROBLEM 7 - 49,
Jennings
p.495 in Bergman, et al.
A long, cylindrical, electrical heating element of diameter D = 10 mm, thermal
conductivity k = 240 W/m-K, density = 2700 kg/m 3, and specific heat cP = 900 J/kg-K is
installed in a duct for which
CHE 3103
2015
Heat Transfer Processes
Jennings
Spring,
HOMEWORK # 8: Heat Exchangers
( due Friday, 3 / 20 )
Problem 8 A.
( original )
The temperature of a well-mixed reactor is maintained at a constant temperature (T) by
immersing it in a well-mixed tank
CHE 3103
2015
Heat Transfer Processes
Jennings
Spring,
HOMEWORK # 2: Conduction
( due Friday, 1 / 30 )
1. [Problem 2-6, p.96 in Bergman, et al.] A composite rod consists of two different
materials, A and B, each of length L. The thermal conductivity of Ma
CHE 3103
2015
Heat Transfer Processes
Jennings
Spring,
HOMEWORK # 3: Conduction
( due Friday, 2 / 6 )
1. [Problem 2-34, p.101 in Bergman, et al.] One-dimensional, steady-state conduction
with uniform internal energy generation occurs in a plane wall with
CHE 3103
2015
Spring,
HEAT TRANSFER PROCESSES
This course is one of a three course sequence dealing with theory and applications of transport phenomena (CHE 3101:
transport of momentum, CHE 3103: transport of energy, and CHE 3104: transport of mass). Ther
Introduction to Convection:
Flow and Thermal Considerations
Chapter Six and Appendix E
Sections 6.1 through 6.8
and E.1 through E.3
Boundary Layer Features
Boundary Layers: Physical Features
Velocity Boundary Layer
A consequence of viscous effects
assoc
External Flow:
The Flat Plate in Parallel Flow
Chapter 7
Section 7.1 through 7.3
Physical Features
Physical Features
As with all external flows, the boundary layers develop freely without constraint.
Boundary layer conditions may be entirely laminar, la
CHE 3103
Jennings
RADIATION EXCHANGE BETWEEN SURFACES
[ Chapter 13 in Bergman, et al. ]
THEORY
View factor section 1
qi,j defined as rate at which radiation leaving area i is intercepted by area j
Ji = radiosity of area i
Fi,j = qi,j / Ai Ji = fraction of
CHE 3103
Jennings
RADIATION
[ Chapter 12 in Bergman, et al. ]
CONCEPTS
Theory
Quantized energy photons
Particles / waves
Frequency / wavelength = c /
= wavelength (typical units: microns, 106 m)
= frequency (s1)
c = speed of light (= 2.998x108 m/s in v
CHE 3103
Jennings
PROBLEM 6 - 7,
p.350 in Bergman et al.
Parallel flow of atmospheric air over a flat plate of length L = 3 m is disrupted by an
array of stationary rods placed in the flow path over the plate.
Laboratory
measurements of the local convecti
CHE 3103
Jennings
INTRODUCTION
COURSE OUTLINE
Topics
Grading
Textbook different perspectives, emphases
Office
POLICIES
Attendance
Late homework
Make-up exams
Extra credit
Cheating
REVIEW
ENERGY BALANCES
First Law of Thermodynamics conservation of energy
S
CHE 3103
Jennings
CONVECTION Internal Flow
[ Chapter 8 in Bergman, et al. ]
DEFINITION
Flow between flat plates, within tubes, channels
Fluid velocity, temperature
Approach constant values at finite distance from surface
Boundary conditions: du/dy = dT/dy
CHE 3103
Jennings
CONVECTION Free
[ Chapter 9 in Bergman, et al. ]
PHYSICAL DESCRIPTION
Driving force buoyancy
Density difference due to temperature difference
As temperature increases, density decreases
High T (low ) over low T (high ) stable, no flow
Lo
CHE 3103
Jennings
HEAT EXCHANGERS
[ Chapter 11 in Bergman, et al. ]
TYPES OF HEAT EXCHANGERS
Concentric tube (double-pipe) Fig.11.1, p.706
Co-current (parallel) flow feed of hot and cold fluids enter at same end
Counter-current flow feed of hot and cold f
Fouriers Law
and the
Heat Equation
Chapter Two
Fouriers Law
Fouriers Law
A rate equation that allows determination of the conduction heat flux
from knowledge of the temperature distribution in a medium
Its most general (vector) form for multidimensional
Radiation Exchange Between Surfaces:
Enclosures with Nonparticipating
Media
Chapter 13
Sections 13.1 through 13.5
Basic Concepts
Basic Concepts
Enclosures consist of two or more surfaces that envelop a region of space
(typically gas-filled) and between w
Condensation
Chapter 10
Sections 10.6 through 10.11
General Considerations
General Considerations
Heat transfer to a surface occurs by condensation when the surface temperature
is less than the saturation temperature of an adjoining vapor.
Film Condensa
CHE 3103
Jennings
CONVECTION Boiling and Condensation
[ Chapter 10 in Bergman, et al. ]
APPLICATIONS IN CHEMICAL ENGINEERING
Reactor operation
Reactions often performed at high temperatures to improve kinetics
Reactants normally heated past normal boiling
CHE 3103
Jennings
TERRESTRIAL RADIATION BALANCE
[ Section 12.9 in Bergman, et al. ]
MAJOR INPUTS Figure 12.28(c)
Solar radiation
At top of atmosphere
342 W/m2
Reflected by atmosphere 77
Reflected by surface
30
Absorption by atm
67
Net solar input
1
CHE 3103
PROBLEM 6 35,
Jennings
p.424 in Bergman, et al.
For flow over a flat plate of length L, the local heat transfer coefficient h x is known to
vary as x1/2, where x is the distance from the leading edge of the plate. What is the
ratio of the average
CHE 3103
PROBLEM 6 - 38,
Jennings
p.424 in Bergman, et al.
[ modified ]
Consider parallel flow of air over a flat plate. The free stream temperature is 300 K. The
free stream velocity is u = 2 m/s. Determine the distance from the leading edge at
which tra
CHE 3103
Jennings
Problem 7 - 9,
p.488 in Bergman, et al.
[ modified ]
An electric air heater consists of a horizontal array of thin metal strips that are each 10
mm wide and 0.2 m long. Twenty-five strips are arranged side by side, forming a
continuous a
CHE 3103
PROBLEM 7 - 2,
Jennings
pp.486-487 in Bergman, et al.
Engine oil at 100 oC and a velocity of 0.1 m/s flows over both surfaces of a 1-m-long flat
plate maintained at 20 oC. Determine: (a) the thermal boundary layer thickness at the
trailing edge;
CHE 3103
PROBLEM 6 39,
Jennings
p.424 in Bergman, et al.
Forced air at T = 25 oC and u = 10 m/s is used to cool electronic elements on a circuit
board. One such element is a chip, 4 mm x 4 mm, located 120 mm from the leading
edge of the board. Experiments
CHE 3103
2015 Heat Transfer Processes
Jennings
Spring,
HOMEWORK # 13 Radiation Exchange
( due Friday, 4 / 24 )
1. [Problem 13-7, pp.904-905 in Bergman, et al.] Consider the right-circular cylinder of
diameter D, length L, and the areas A1, A2, and A3 repr