# EML 4304L Thermal Fluids Lab Thermal Conduction

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```					  EML 4304L Thermal Fluids Lab

Thermal Conduction
Experiment # 3

Mechanical Engineering Department
FAMU/FSU College of Engineering
Outline

•Purpose of the lab
•Testing Equipment
• The types of equipment setup
•Units 3 and 4
•Units 1 and 2
•Heat sinks
•Drain tubes
• Calculations Needed for Experiment

Mechanical Engineering Department
FAMU/FSU College of Engineering
PURPOSE
• Conduct a series of thermal conduction
experiments which examines the effects on heat
transfer with varying cross-sectional area and
distance.
– Using this thermal conduction information derive
Fourier’s law of thermal conduction.
• Analyze the temperature variance in a series of
metal rods that are in physical contact.
– From this information determine thermal resistance
and contact resistance.

Mechanical Engineering Department
FAMU/FSU College of Engineering
Testing Equipment
For Experiments

Mechanical Engineering Department
FAMU/FSU College of Engineering
Units
1-4
Drain tube

Temperature
Mechanical Engineering Department
FAMU/FSU College of Engineering
On/Off Switches for
Units 1-4

Thermocouple
Selector
1-10                                           Unit Selector
1-4

Mechanical Engineering Department
FAMU/FSU College of Engineering
Units 3-4

Mechanical Engineering Department
FAMU/FSU College of Engineering
Digital Temperature
Indicator (ºF)

Mechanical Engineering Department
FAMU/FSU College of Engineering
Equipment for
Thermal Conduction Test
Units #3 and #4

Mechanical Engineering Department
FAMU/FSU College of Engineering
Heat flow
for units
3 and 4

Mechanical Engineering Department
FAMU/FSU College of Engineering
Heat flow
for units
3 and 4

Notes: Do NOT adjust the flow valves.

Mechanical Engineering Department
FAMU/FSU College of Engineering
UNIT #3
Q=KA*ΔT/Δx
K = coeff. of therm. conductivity                    NOTE: K is
unknown and
must be
T2                                          T1         determined

x2                    x1
Mechanical Engineering Department
FAMU/FSU College of Engineering
UNIT #4
Q=KA*ΔT/Δx
K = coeff. of therm. conductivity                    NOTE: K is
unknown and
must be
T10                                         T1         determined

x2                    x1
Mechanical Engineering Department
FAMU/FSU College of Engineering
Equipment
Thermal Resistance and
Contact Resistance Test
Units #1 and #2

Mechanical Engineering Department
FAMU/FSU College of Engineering
Heat flow
for units
1 and 2

Mechanical Engineering Department
FAMU/FSU College of Engineering
Heat flow
for units
1 and 2

elements are enclosed in the insulating jacket. Figure1 illustrates the schematics of the apparatus. The dimensions of the tapered rod are indicated
in Fig. 2.

Mechanical Engineering Department
FAMU/FSU College of Engineering
Units #1 and #2
Steel              Cu               Stainless
(Mg)              (Al)              Steel

T10                                                    T1

x2                                          x1
Contact Resistance

Mechanical Engineering Department
FAMU/FSU College of Engineering
Heat Sinks
• One water cooled heat sink is located on each unit
• Units #1 and #2 they are located at extreme end of
the assembly away from the heat source
• Units #3 and #4 are located on the top of each unit
• The heat sinks will be used to determine heat lost
by each unit.
• Q=mwCp(ΔT)

Mechanical Engineering Department
FAMU/FSU College of Engineering
Drain Tube
Flow Rate Calculations

Mechanical Engineering Department
FAMU/FSU College of Engineering
from heat sinks

Mechanical Engineering Department
FAMU/FSU College of Engineering
Drain tube
to measure
flow rate

Also will need
a stopwatch
to time fluid
flow

Mechanical Engineering Department
FAMU/FSU College of Engineering
Calculations

Mechanical Engineering Department
FAMU/FSU College of Engineering
Calculations

Conservation of Energy
(in a perfect world)

qin = q out

Conservation of Energy
(in our world)

qin = Cq out
Where C is a constant which represents any losses not accounted for.

Mechanical Engineering Department
FAMU/FSU College of Engineering
Units #1 and #2
Steel           Cu                 Stainless
(Mg)           (Al)                Steel

Heat                                                             Heat In
Sink

Qout=Qin

Q=mwCp(ΔT)

Rt,c= ΔT/Q

Mechanical Engineering Department
FAMU/FSU College of Engineering
Calculations

T
Rt ,c 
q

Thermal Contact Resistance
Rt,c = Thermal contact resistance
T = Temperature change
q = Heat flux

Mechanical Engineering Department
FAMU/FSU College of Engineering
UNIT #3

Qout                                            Qin

Qout=Qin

x2                     x1                Q=mwCp(ΔT)

Q=KA ΔT/Δx

Mechanical Engineering Department
FAMU/FSU College of Engineering
Calculations
m w C p T                                 T
(1)   q                               (2)      q  KA
t                                    x
(1) – Rate of heat flow at the sink
mw = mass of cooling water displaced in time t
Cp = Specific heat of water at constant pressure
T = (Tout - Tin) of cooling water
t = time required to displace a volume Vw of water

(2) – Relationship between heat flow and temperature difference
K = proportionality constant
A = cross-sectional area
T = temperature difference of the material
x = distance
Mechanical Engineering Department
FAMU/FSU College of Engineering
Calculations

• Q=KA ΔT/Δx             Q=-KA dT/dx

T

dT/dx

x

Mechanical Engineering Department
FAMU/FSU College of Engineering
Errors
• Time
Flow rate
• Heat Losses
Not perfectly insulated

Mechanical Engineering Department
FAMU/FSU College of Engineering

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 views: 17 posted: 12/11/2011 language: pages: 29