ILC Space Systems is developing a washer-dryer and a refrigeerator-freezer for the Freedom space station. The unique environmental and low-maintenance requirements of space station appliances may also be useful for home appliances.
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Astronauts in space have limited power and water supplies, are dependent on a sensitive life-support system, and can't get service-people to come fix broken equipment. In other words, many of the challenges of appliance design for space habitats aren't much different from those faced on Earth.
"A space station is just a small-scale environmental-control life-support system," explains Peter E. Glaser, vice president of space operations at Arthur D. Little, Inc. Earth, he says, is the same but on a grand scale. "Everything is recirculated. We have to be concerned about what goes into the water and air because eventually we will drink or breathe it again." The Cambridge, Mass., technology and management consulting firm, a subcontractor to ILC Space Systems, is developing two energ-efficient appliances for NASA's space station Freedom: a washer-dryer that uses a gentle detergent and 80 percent less water than other machines, and an easy-to-repair refrigerator-freezer designed to prevent leaks of ozone-damaging refrigerant.
"In addition, of course, there are requirements for an appliance that are unique to use in space," Glaser continues. In a compactly designed space station, he adds, "we have to have low noise because people may have to sleep next to these items. And there are stringent vibration requirements." These traits could be beneficial in home appliances as well.
Clean clothes are as important to astronauts as they are to the earthbound. "It costs thousands to send up a pound of anything," says Glaser, so astronauts are allowed only a few pieces of clothing. Besides, he says, "we know it helps morale to have clean clothes."
The washer-dryer uses 1.1 gallons of water to clean each pound of clothes--compared with a typical seven gallons per pound for Earth's current models--and uses 20 percent less energy than other machines. It holds seven pounds of clothes--about half the amount of a conventional machine--though it could be sized for larger loads. Rather than agitating clothing for cleaning, it extracts soil with a detergent solution.
"We call it a Pressure Activated Bladder Washer," says Glaser, because an inflatable diaphragm "bladder" is expanded to push the clothing against the machine's inner wall. Injected detergent does the rest (see illustration); the bladder is retracted for air-drying. "The process takes about three hours," says Glaser. The exhaust air is filtered, as with conventional machines, and excess heat is reclaimed before the air is returned to the space station atmosphere.
So how does it perform? The washer won't clean everything an earthbound washer will, such as mud, unless clothes are soaked and the mud is removed beforehand. To gauge the machine's ability to tackle the body soils and food stains more commonly found in space, researchers devised the "jogger test." "We gave jorrers the same type of cotton underwear that would be used on the space station," explains Glaser. "For three weeks, we washed their clothes in our prototype laundry and in a conventional unit." A panel comprised of the joggers and others judged the results favorably.
When it comes to refrigeration needs a space station, once again, is a microcosm of Earth. The modular refrigerator-freezer, the second appliance being developed, offers a removably compartment containing a cooling unit that can be replaced, quips Glaser, without waiting for the repairman. The device is also designed to limit and contain any refrigerant leakage, which is even more of a threat to the astronauts' oasis than it is to Earth.
"On Earth, we thought until recently that if chloroflurocarbons leak into the atmosphere, nothing happens," says Glaser. "We now know that things do happen: We call it the ozone hole! In space, good design is even more critical because if a refrigerant seeps into the environmental control life-support system, it may break down and create some toxic compounds."
The space-journeying refrigerator-freezer, about the same size as a conventioanl one, will use bromotribluoromethane refrigerant. Any leaks would be detected by a pair of sensors and indicated by a light on the display panel. Depending on whether a combination refrigerator-freezer or freezer only is needed, an insertable divider can create compartments with independent temperature control. The refrigerator uses a conventional vapor-compression cycle for cooling, but the components are arranged differently from the usual home unit.
Instead of placing heat-exchanger coils in the storage cabinet and on the back of the refrigerator--a common home-refrigerator's cooling equipment is in a sealed box. That box, the only place where refirgerant is located, is sealed within another container, called the modular refrigeration unit. The entire unit is replaceable.
Small drawers restrain food, film, and laboratory material in the storage cabinet--important in the microgravity of space--while allowing adequate airflow for cooling. The drawers also greatly reduce the loss of cold air when the door is opened, saving energy.
Practical for Earth?
Arthur D. Little engineers recently showed the washer concept to members of the Chicago-based Association of Home Appliance Manufacturers. While manaufacturers were interested in learning about the technology, it may be awhile before its terrestrial use is determined to be practical, says Mary Gillespie, assistant director of communications for the organization. The refrigerator has yet to be demonstrated to a similar manufacturing group.
In any event, Glaser hopes ideas from these appliances will someday find their way into our kitchens and laundries. "I think we can have a successful technology transfert," he says.
DiChristina, Mariette. "Appliances from space. (space station technology)." Popular Science Mar. 1992: 56+. Academic OneFile. Web. 11 Dec. 2009.
Gale Document Number:A11839902
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