Thermoelectric
High-Temperature Cooling System
Introduction
A carefully engineered
application of thermoelectric cooling devices opens up new
possibilities in MWD/LWD and wireline
tools or any electronics operating in temperature environments
exceeding 150°C. At these elevated temperatures, sensor
and printed circuit board component selection are typically
limited in both type and availability. APS Technology has developed
an efficient system utilizing thermoelectric coolers in a unique
geometry to efficiently cool critical elements of a downhole
system†. The design has been tested, as described below,
for characterization and determination of the coefficient of
performance.
System
Evaluation
The test
assembly was comprised of an 11" x 1" circuit
board dissipating 15 watts of power and mounted in a 2" pressure
barrel. A heat transfer model for the specific package was
developed to optimize thermoelectric module size and resultant
cooling
capability. To simulate downhole conditions, the module was
tested in an agitated, heated oil bath maintained at 200°C.
The package was instrumented with thermocouples located on
both the hot and cold sides and tested at various input power
levels to a peak of 9.5 amps. Depending on the internal heat
generated, the packaging geometry and available power, differential
cooling of 30° to 50°C was demonstrated in ambient
temperatures up to 200°C.
Applications
This
flexible cooling system can be applied to a variety of
applications, such as:
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• |
In an MWD/LWD tool, a critical, temperature-limiting
component (e.g., a scintillator) can be cooled, thereby
increasing the temperature rating of the entire tool. |
| • |
Critical electronics
in a wireline tool can be cooled to extend the useful
range of operation. In one application,
a tool that employed DSP chips rated at 175°C was made
operable to 200°C. |
| • |
Similar improvements are possible in other high-temperature
industrial applications, downhole or at the surface. |
APS can
adapt this design for any application; contact us for an
evaluation.
† U.S.
Patents 5,931,000 & 6,134,892
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aps-tech.com