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Interior/Exterior
Artist rendering of Columbus Laboratory Module for the
International Space Station
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Refrigerator/Freezer
Rack (RFR) Highlighted areas depict placement of Marlow
Industries designed finned heat exchanger units
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Image
of finned heat exchanger unit for RFR
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Marlow
Develops Refrigerator Freezer Racks for the International Space Station
The International
Space Station serves mainly as a research laboratory that can provide the
special conditions of space on a permanent basis. The space station
program will aim at a successful multidisciplinary utilization of the
space station in the fields of research in space, technology, geoscience
and space exploration. In order to accomplish this daunting mission, the
station will be equipped with Columbus, a space laboratory scheduled for
last module placement sometime in 2004. Nearly 8 meters in length and 4.5
meters in diameter, the module will house 10 International Standard
Payload Racks (ISPRs) designed for a variety of applications including
communications, power supply and temperature control. Once deployed this
module will be instrumental in space based research for an estimated
operational lifespan of over 10 years.
Marlow Industries has lent
its extensive experience in space-based thermoelectrics to the development
of the Refrigeration Freezing Rack (RFR). The RFR is a specially designed
refrigerator/freezer that will be used by astronauts on the Space Station
for food storage and transportation. Marlow has custom designed finned
heat exchangers to cool the RFR. To avoid frost on the fins, a system has
been included to eliminate water by capillarity.
General Information on
Space Refrigeration/Freezing
Refrigerator/freezer
applications for space applications are usually found in three varieties.
These are deep freezing of food or samples (-30°C), refrigeration to 4°C,
and incubators (40°C to 4°C). Marlow provides a heat exchanger
(air-to-air or water-to-air) using thermoelectric coolers as the active
cooling or heating component. This application requires a close working
relationship with our customer because of the need to coordinate the fans
and the interface with the heat exchanger. These applications require
high-performance products and are produced in low volume (fewer than 10
units). They are custom products and are not cost-sensitive.
Advantages of
Thermoelectrics for this Application
The advantage
of thermoelectrics is the use of solid-state technology that does not
require Freon or bearings that contain oil. Due to the restrictions on
Freon and oils in the space equipment, compressor-based systems are
expensive and unreliable. Thermoelectrics, while less efficient from a
electrical/thermal standpoint, offer dramatically improved reliability and
safety. In addition, thermoelectric coolers have an excellent track record
in space applications. In the case of incubators, thermoelectric coolers
are ideal as they can provide both heating and cooling.
Specific Marlow
Advantages
Space systems
must be power-efficient for a given set of design parameters. To improve
electrical efficiency, there must be considerable optimization to the
thermoelectric cooler, heat sinks, fans, and interfaces. This requires
extensive modeling experience and capability. Marlow has this experience,
along with test and assembly experience. Marlow also has high-performing
TE material that improves the electrical thermal performance of the
assembly. Improvements in coefficient of performance of 10% to 20% over
our competitors' TE coolers are common.
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