Embed Size (px)
DESCRIPTION
heat transfer
Citation preview
BDA 40303
FINITE ELEMENT METHOD
WEEK 10
LABORATORY SESSIONS
By
Dr. Izzuddin Zaman
BD
A 4
03
03
D
r. Izzu
dd
in Z
am
an
1
EXERCISE 1: ONE DIMENSIONAL HEAT TRANSFER FIN PROBLEM
BD
A 4
03
03
D
r. Izzu
dd
in Z
am
an
2
Determine the temperature distribution along the fin using 4
elements.
Aluminum fins of a rectangular
profile are used to remove heat
from a surface whose temp. is
100 C. The temp. of ambient
air is 20C.
The thermal conductivity of the
aluminum is 168W/mC.
The natural convective heat
transfer coefficient associated
with the surrounding air is
30W/mC. The fins are
80mmlong, 5mm wide, and
1mm thick.
EXERCISE 1: TIPS FOR SOLUTION
Type of Analysis - 2D, Thermal > Steady State
Model>Global Properties - enable Element field values
Model> Materials> Geometric - Choose Rectangular Bar
Materials> Thermal – Isotropic, enter thermal conductivity
Create Nodes
Create Elements – Line2-Fin
Constraints > Add/Edit, set temperature to 100 at node 1.
Loads > Convection– Add to selected faces – Insert ambient
temperature and heat transfer coefficient
BD
A 4
03
03
3
Dr. Iz
zu
dd
in Z
am
an
EXERCISE 2: COMPOSITE WALL
BD
A 4
03
03
4
Dr. Iz
zu
dd
in Z
am
an
A wall of industrial oven consists of three different material.
The first layer is composed of 5 cm of insulating cement with a
thermal conductivity of 0.08W/mC. The second layer is made from
15 cm of 6-ply asbestos board with a thermal conductivity of
0.074W/mC. The exterior consists of 10 cm common brick with a
thermal conductivity of 0.72W/mC.
The inside wall temperature of the oven is 200 C and the outside
air is 30C with a convection coefficient of 40W/mC.
Determine the temperature distribution along the composite wall.
EXERCISE 2: TIPS FOR SOLUTION
Type of Analysis - 2D, Thermal > Steady State
Model>Global Properties - enable Element field values
Model> Materials> Geometric - Choose Rectangular Bar
Materials> Thermal – Isotropic, enter thermal conductivity
Create Nodes
Create Elements – Line2-Fin
Constraints > Add/Edit, set temperature to 200 at node 1.
Loads > Convection– Add to selected faces – Insert ambient
temperature and heat transfer coefficient
BD
A 4
03
03
5
Dr. Iz
zu
dd
in Z
am
an
EXERCISE 3: 2-D HEAT TRANSFER
BD
A 4
03
03
6
Dr. Iz
zu
dd
in Z
am
an
A square industrial chimney constructed from concrete with a
thermal conductivity value of k = 1.4 W/mC.
The inside structure temperature of the chimney is constant at
100C.
The exterior surface is exposed to the surrounding air at 30C with
a corresponding natural convection h = 20 W/m2C.
Determine the temperature distribution of 1/8 model of the cross
sectional chimney. You have to use node and element numbers as
suggested in the above figure.
EXERCISE 3: TIPS FOR SOLUTION
Type of Analysis - 2D, Thermal > Steady State
Model>Global Properties - enable Element field values
Model> Materials> Geometric - Choose None
Materials> Thermal – Isotropic, enter thermal conductivity
Create Nodes – there are 9 nodes
Create Elements – quad4 and tri3
Constraints > Add/Edit, set temperature to 100 at node 1&2.
Loads > Convection– Add to selected faces – Insert ambient
temperature and heat transfer coefficient
BD
A 4
03
03
7
Dr. Iz
zu
dd
in Z
am
an
EXERCISE 4: UNSTEADY/TRANSIENT
BD
A 4
03
03
8
Dr. Iz
zu
dd
in Z
am
an
A plate is of cross-section thickness L = 0.1m has an initial temp of
T0 = 250C, when it is suddenly immersed into an oil bath of
temperature Ta = 50C with heat transfer coefficient of h =
80W/m2C.
The plate material properties are thermal conductivity k =
204W/mC, density ρ = 2707 kg/m3 and specific heat Cp = 896
J/kg C.
It is required to determine the time taken for the slab to cool to a
temperature of 200C.
Try check with different plate’ thickness
EXERCISE 4: TIPS FOR SOLUTION
Type of Analysis - 2D, Thermal > Transient
Model>Global Properties – No of Time steps 500, time step 1
Model>Global Properties - enable Element field values
Model> Materials> Geometric - Choose None
Materials> Mechanical – Isotropic, enter density
Materials> Thermal – Isotropic, enter thermal conductivity and
specific heat
Create Nodes – thickness is 0.1 and height 0.2
Create Elements – quad4
Element> Refine Custom – R=4, S=8, insert tolerance
Constraints > Add/Edit, all nodes set temperature to 250 at
initial time step 0
Loads > Convection– Add to selected faces – Insert ambient
temperature and heat transfer coefficient
BD
A 4
03
03
9
Dr. Iz
zu
dd
in Z
am
an
TASK 5: ALUMINUM FINS
BD
A 4
03
03
10
Dr. Iz
zu
dd
in Z
am
an
As a research engineer in a company you are requested to investigate two types of aluminum fins that will be implemented to remove heat from a surface whose temperature is 150C. The temperature of surrounding air is 25 ◦C. The natural heat transfer coefficient associated with the surrounding air is 30W/m2C. The thermal conductivity of aluminum is 168W/mC. Determine which one of the fin that you would suggest. Your report should be concise, attractive and very convincing.
