Testing a Peltier Element

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Testing a Peltier Element
Ingrid Ajaxon, Johan Lindahl Harald
Nyberg Advisor C-G. Ribbing
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Theory

• The Peltier-effect describes the heat current
  that arises when an electrical current is led
  through an interface between to conducting
  materials

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Heat current

• The heat current between two conductors
• Heat is generated if ?Agt ?B and the electrical
  current flows from A to B

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Commercial Peltier elements

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Cooling power of a single pair of junctions

• Limiting factors
• Resistive heating
• Heat dissipation
• Cooling power

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Total cooling power

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Experimental set-up

Sketch of the experimental setup
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Measurement

• Measurement started at RT (23ºC)
• and I0
• DC increased stepwise from 0 to 2.5 A,
• in steps of 0.1 A
• U, I and T registered after each step

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Results

The temperature inside the cavity as a function
of the current through the Peltier element
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The temperature difference between the cavity and
the surroundings
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At stationary temperature, the heat transported
out of the cavity (Ptotal) is equal to the heat
flowing into the cavity
Assume that this heat flow is linearly dependent
on the temperature difference between the inside
and outside of the cavity (?T) through some
constant (C)

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?T can now be written as a function of the
current (I)
The constants in this equation can be identified
from the polynomial fitted to the measured data

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Limiting factors

• Thermal insulation of the cavity
• Losses through radiation
• Heat dissipation on the hot side
• Peltier coefficient of the element
• Thermal conductivity of the element

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Questions?