University of Duhok
College of Engineering
Mechanical Engineering Department
PRACTICAL EXPERIMENTS
HEAT TRANSFER LABORATORY
Experiment Forced Convection – Flow Abstruction
And Temperature Distribution Across The
Extended Surfaces
Prepared By: Pshtiwan Ashraf -Group (A)-
Assist. Prof.:Dr. Arkan Fawzi Saeed (Head
OFmech.Eng. Dept.)
Date: 19-4-2022
INTRODUCTION
Convection is one of the major modes of heat transfer and mass
transfer. Forced convection is a mechanism or type of heat
transport in which fluid motion is generated by an external
source (like a pump, fan, suction device, etc.). It should be
considered as one of the main methods of useful heat transfer
as significant amounts of heat energy can be transported very
efficiently and this mechanism is found very commonly in
everyday life, including central heating, air conditioning, steam
turbines, and in many other machines. forced convection is a
special type of heat transfer in which fluids are forced to move,
in order to increase the heat transfer This forcing can be done
with a ceiling fan, a pump, suction device, or other. Many people
are familiar with the statement that "heat rises". This is a
simplification of the idea that hot fluids are almost always less
dense than the same fluid when cold, but there are exceptions
(see the layers of the atmosphere) and thermohaline circulation
for exceptions). This difference in density makes hotter material
naturally end up on top of cooler material due to the higher
buoyancy of the hotter material.
Objective: 1- To compare the obstruction to flow caused by each heat
transfer.
2- And to find the different temperatures between each
surface.
THEORY
In this experiment we are transferring heat by forced convection
to do this work we increase the area by taking fins, Convection is
a complex heat transfer method, but can be expressed by
Newton's Law of Heating and Cooling, which simply says that the
rate of convection heat transfer, expressed in the units is
proportional to the difference between the initial temperature
of the material and the final temperature of the material through
a proportionality constant
Applications
This mechanism is found very commonly in everyday life, including
central heating, air conditioning, steam turbines, and many other
machines. Forced convection is often encountered by engineers
designing or analyzing heat exchangers, pipe flow, and flow over
a plate at a different temperature than the stream. Other
applications for forced convection include systems that operate
at extremely high temperatures for functions for example
transporting molten metal or liquefied plastic.
PROCEDURE
a. Take the fan from the top of the device.
b. Fit one of the heat transfer surfaces. For the first time, we
take the flat heat transfer surface.
c. Create a table for our readings.
d. For aflat heat transfer surface, we set the velocity at 3.2
m/s for finned and pinned heat transfer surface we set (3.1,
2.5) m/s of velocity.
Result analysis
Table
Heat Transfer Surface: Finned
Power= 30 W
Air Flow= 3 m/s
Forced Convection
Position 1
7.5 mm
Position 2
19.5 mm
Position 3
31.5 mm
Position 4
43.5mm
Position 5
55.5 mm
Position 6
67.5 mm
prope
temperature
Tp(T3)
23.2
20.8
20.1
19.3
19.2
19.2
Surface
Temoeratur
Ts(T2)
37.2
37.2
37.2
37.2
37.2
37.2
Inlet
temperature
Tin(T1)
16.1
16.1
16.1
16.1
16.1
16.1
Difference
Temperature
(Tp - Tin)
7.1
4.7
4
3.2
3.1
3.1
Graph
Relation between position & Temperature
8
7
Temperature (Tp - Tin)
6
5
4
3
2
1
0
0
10
20
30
40
position (mm)
50
60
70
80