Conduction-Convection systems
and Fins
What are Fins ?
Fins are extended surfaces used to increase
the rate of heat transfer.
It is made of highly conductive materials such
as aluminum.
Analysis of Fins
Steady state operations
No heat generation
Constan
ChE 300: Transport Phenomena II
(Heat Transfer)
M. Mozahar Hossain PhD PEng
Department of Chemical Engineering
King Fahd University of Petroleum &
Minerals
Dhahran 31261, Saudi Arabia
Case 1: ?
Case-2
Case-2
Handouts [X
List of Symbol:
L Length
Lc Corrected n length (Chap. 2)
m Mass
r51 Mass rate of ow
M Molecular weight (Chap. ll)
:1 Molecular density
N Molal diffusion rate, moles per
unit time (Chap. 11)
p Pressure, usually N/ml, Pa
Perimeter
q Heat-transfe
Heat Exchangers
Heat Exchangers
Chee 318
1
Heat Exchangers
A heat exchanger is used to exchange heat between two fluids
of different temperatures, which are separated by a solid wall.
Heat exchangers are used to carry out energy conversion and
utilizati
Empirical and Practical Relations for
Forced-Convection Heat Transfer
Chapter 6
1
Introduction
Convection is the mechanism of heat transfer
through a fluid in the presence of bulk fluid motion.
It is classified as natural (or free) and forced
convection
Effectiveness-NTU method
1
This method is used when the inlet or outlet
temperatures are needed to be evaluated for
a GIVEN HEX.
The LMTD analysis frequently requires a
iterative solution.
The effectiveness-NTU method is based on the
effectiveness of t
Chapter 10
Heat Exchangers (HEX)
1
The application of the heat transfer principles
to the design of HEX is extremely important.
Economics play a key role in the design and
selection of HEX.
Weight and size are also important.
2
Heat exchangers are dev
Flow across tube bank
1
Because many heat exchanger
arrangements involve multiple row of
tubes, the heat transfer characteristics for
tube banks are of important interest.
Tube arrangements could be of two types:
staggered and in-line
2
3
Heat transfer
Steady-State Conduction
One Dimension
Start with the most general heat equation
Heat transfer in one direction
No heat generation
Steady state
Integrating
Fouriers law from x1 to x2 and from
T1 to T2
- For constant k
- For variable
Conduction Thermal Res
Unsteady State Conduction
Chapter 4
1
Transient Heat Conduction: Analytical Solution
Consider an infinite plate of thickness 2L, initial
temperature = Ti, at time equal zero the surfaces are
lowered to T=T1
2
Lumped Heat Capacity
Energy Balance:
Where
Flow across cylinders and
spheres
Flow across cylinders and spheres is important as the
flow inside tubes.
The boundary layer determines the heat transfer
characteristics.
The pressure gradient causes a boundary layer
separation on the back side when t
Radiation Heat Transfer
Chapter 8
1
Introduction
Conduction and convection heat transfer
require the presence of a medium while
radiation does not.
All objects with temperatures above absolute
zero radiate energy.
Energy is transferred by electromagnet
Chapter 3
Steady-State Conduction
Multiple Dimensions
The heat Equation
The heat flow in the x and y directions
The total heat flow at any point in the material
is the resultant of the qx and qy at that point
Isotherms and Heat Flow Lanes
Shape Factor
Chapter 5
Convection Heat Transfer
1
Introduction
In the previous chapters, we discussed the
mechanism and calculations of conduction
heat transfer.
Convection was considered only as a boundary
condition for the conduction problem.
In this chapter, we
Forced Convection
9 Fluid motion past a surface increases the rate of heat transfer
between the surface and the fluid.
9 For example, a brisk wind increases our discomfort on a cold
day.
9 A flowing fluid transports thermal energy by virtue of motion.
9 F
Chapter 3
One-Dimensional Steady-State Conduction
Chapter 3
Chee 318
1
Course Road Map
Chapter 1:
E in E g E out E st
Conservation of Energy
When there are no contributions of kinetic, potential, internal energy and work
E in qin
and E out qout
Can be wri
King Fahd University of Petroleum & Minerals
Department of Chemical Engineering
CHE-300: Transport Phenomena II (Heat Transfer)
Fall 2015 (Term 151)
Instructors:
Dr. Mamdouh A. Al-Harthi (Coordinator)
Dr. Isam Al-Jundi
Course Description:
Modes of heat t
King Fahd University of Petroleum & Minerals
Department of Chemical Engineering
CHE-300: Transport Phenomena II (Heat Transfer)
Spring 2014/2015 (Term 142)
Instructors:
Dr. Isam H. Aljundi (Coordinator)
Dr. Abdulhadi Aljuhani
Course Description:
Modes of
CHE 401 : Process Dynamics and Control
Dr. Abdallah Al-Shammari
Department of Chemical Engineering
KFUPM
Topic: Feedback Controllers (Ch.7)
CHE401: Process Dynamics and Control. L17
Abdallah
Proportional-Integral-Derivative (PID) controllers
CHE401: Proce
CHE 401 : Process Dynamics and Control
Dr. Abdallah Al-Shammari
Department of Chemical Engineering
KFUPM
Topic: Theoretical Models of Chemical Processes (CH.2)
CHE401: Process Dynamics and Control. L2
Abdallah
Process modeling:
Definition of dynamic model
Continue the example from the previous lecture
Herein, we made a step change in Ti form 0 to 10 K after 5 minutes
Then, we another step change in Q form 0 to -3000 KJ/min after 120 minutes
CHE 401 : Process Dynamics and Control
Dr. Abdallah Al-Shammari
Department of Chemical Engineering
KFUPM
Topic: PID Controller Design, Tuning, and
Troubleshooting (ch.11)
CHE401: Process Dynamics and Control. L28
L24-27
Abdallah
Performance criteria for c
CHE 401 : Process Dynamics and Control
Dr. Abdallah Al-Shammari
Department of Chemical Engineering
KFUPM
Topic: Control System Instrumentation (ch.8)
Abdallah
CHE401: Process Dynamics and Control. L18
Control system instrumentation
CHE401: Process Dynamic
CHE 401 : Process Dynamics and Control
Dr. Abdallah Al-Shammari
Department of Chemical Engineering
KFUPM
Topic: Dynamic Behavior and stability of closed-loop
control systems (ch.10)
L20 - L23
CHE401: Process Dynamics and Control. L20
1
Abdallah
Example:
C
CHE 401 : Process Dynamics and Control
Dr. Abdallah Al-Shammari
Department of Chemical Engineering
KFUPM
Topic: Transfer Function and State-space models (Ch.3)
CHE401: Process Dynamics and Control.
Abdallah
L7
Transfer Function - introduction
Input
u(t)
U
CHE 401 : Process Dynamics and Control
Dr. Abdallah Al-Shammari
Department of Chemical Engineering
KFUPM
Topic: Feedback Controllers (Ch.7)
Abdallah,
CHE401: Process Dynamics and Control. L16
Proportional-Integral-Derivative (PID) controllers
2.
Integral
CHE 401 : Process Dynamics and Control
Dr. Abdallah Al-Shammari
Department of Chemical Engineering
KFUPM
Topic: Laplace Transforms (Appendix A)
Abdallah
CHE401: Process Dynamics and Control. L4
Solving ODE:
Requires analytical or numerical integration of
CHE 401 : Process Dynamics and Control
Dr. Abdallah Al-Shammari
Department of Chemical Engineering
KFUPM
Topic: Introduction to process Dynamics and Control
CHE401: Process Dynamics and Control.
Abdallah, L1
Simple example:
Control the temperature and flo
CHE 401 : Process Dynamics and Control
Dr. Abdallah Al-Shammari
Department of Chemical Engineering
KFUPM
Topic: Laplace Transforms (Appendix A)
Abdallah
CHE401: Process Dynamics and Control. L5
Partial Fraction Expansion
Need of partial fraction expansion
CHE 401 : Process Dynamics and Control
Dr. Abdallah Al-Shammari
Department of Chemical Engineering
KFUPM
Topic: Laplace Transforms (Appendix A)
Abdallah,
CHE401: Process Dynamics and Control. L6
Lapalce function: Matlab example
We can use Matlab to obtain