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Using LabPro to Analyze Thermoelectric module as Generator
by Jim Sizemore
Contents
Introduction ..................................................................................................................................... 1
Objectives ....................................................................................................................................... 1
Equipment ....................................................................................................................................... 1
Recording TE Module Data ............................................................................................................ 1
Results ............................................................................................................................................. 2
Conclusion ...................................................................................................................................... 3
List of Figures ................................................................................................................................. 3
List of Links .................................................................................................................................... 3
Introduction
We will do Lab 55A using the LabPro system. Lab 55B (using a TE module as
refrigerator) since the current probe is limited to 600 mA and Lab 55B requires more. This is a
lab that requires so time to perform and LabPro can do a good job of taking many readings at
regular intervals. The “List of Links” refers to prior labs in would be good to be familiar with
before attempting this lab.
Objectives


Set up LabPro to record temperature and power
Begin experiment
Equipment
LabPro system, two temperature probes, voltage probe
Recording TE Module Data
1.
2.
3.
4.
Set up temperature probes and voltage probe
Set up Lab 55A and data collection at 1 per second
Start experiment and begin data collection
Data is shown in Figure 1
Figure 1 – Time-temperature-power data for thermoelectric module
The electrical load is 46,800 Ω and the power column uses the formula V2/R. Either hot
or cold water is used in either chamber. Chamber A diameter is 3.196 cm and depth 3.178 cm.
Chamber B diameter is 3.188 cm and depth 3.22 cm. Volume of A, therefore, is 25.51 cm3 and
B is 25.70 cm3. Maximum temperature on the hot side (B) is 69.11°C and minimum temperature
on the cold side (A) is 7.66°C. If all the heat lost by the hot side is gained by the cold side, the
heat transferred is 787 cal or 3293 J. Actual electrical energy produced is 7.53*10-4 J – an
extremely small efficiency.
Results
Hand gathering this data a student often does not observe the curvature of the data. The
experiment analysis itself asks why the hot side drops more than the cold side rises. The data
above can lead to a discussion of this effect (Room temperature is closer to the cold side and,
thus, the hot side loses heat to the room). Lead students to discuss if the cold side gains heat
from the room (of course it does, only not as much).
Total energy produced in 30 min. is 7.53*10-4 J – much less than the heat transferred thus
showing extremely small efficiency and why this device is not in common use. Lead students to
discuss another device that accomplishes converting heat to energy (a heat engine). Discuss why
Thermoelectric module Using LabPro
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we use heat engines instead of thermoelectric generators. Also discuss why we might use a TE
module in certain circumstances.
Conclusion
In a long experiment, such as this, we can gather much more data than is possible by
hand. Thus we can observe behaviors of the system better.
List of Figures
Figure 1 – Time-temperature-power data for thermoelectric module ............................................ 2
List of Links
1.
2.
3.
4.
5.
6.
Vernier Web Site
LabPro User’s Manual (large, 6.5 Mb file)
LabPro Technical Manual (405 kb)
Basic LabPro Setup and Operation
RC Time Constant and Energy Stored in Capacitor
Ohm’s Law
Thermoelectric module Using LabPro
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