GETTING BY WITHOUT CFA's

Article Tools

Image Gallery

Print

E-mail

Comments

RSS

Because homeowners want as much inside volume as possible while maintaining outside dimensions that will still fit into the kitchen, space is at a premium in refrigerators. Therefore, insulating with five- or six-inch-thick walls is just not acceptable, according to manufacturers.

Efforts to find alternatives are progressing rapidly in the refrigerator industry, but experts say the changes will take a lot of time, and high efficiency may be difficult to maintain. HCFC-22 is used in commercial chillers but isn't effective for achieving temperatures below about 15°F. Efforts are underway to develop a two-stage compressor system that would enable HCFC-22 to be used in residential refrigerator-freezers. More attention is focusing on new refrigerants. HCFC-134a is considered a likely candidate to replace CFC-12, but it will be at least three to five years before the new refrigerant is on the market—assuming it passes testing. Even then, using it will require some changes in compressor design.

More radical refrigeration technologies are also being considered. Some suggest a return to ammonia as the refrigerant (used in very early refrigerators), but ammonia leaks would be smelly and potentially dangerous. One company, Cryodynamics, Inc. of Mountainside, New Jersey, is developing a Stirling-cycle cooling system using helium. Company president Dr. Steven Malaker claims that his technology, which has been used in specialized medical applications for some time, will be simpler, 25% more energy efficient, and no more expensive.

On the insulation side, the most exciting development is the prospect of vacuum-panel insulation. Various companies and research institutes are pursuing several different vacuum-panel technologies. One approach is a hard vacuum like that in a thermos bottle (10-6 torr —about a billionth of an atmosphere). A 1/8-inch-thick panel of this type could insulate to R-15. By doubling or tripling the layers, insulation levels could be further increased, and edge losses kept to a minimum. A non-CFC foam insulation might be used with such a system to protect the vacuum panel and provide rigidity. But even with a layer of foam insulation, the total wall thickness could be less than what is found in today's refrigerators, and the R-value more than double present standards.

Another approach is a soft-vacuum powder insulation. With this technology, a very fine silica powder is put in airtight panels, and a soft vacuum (1/100 to 1/1000 of an atmosphere) is drawn in the panel. Heat transfer from particle to particle in the powder is greatly reduced, and R-values up to R-25 per inch are possible. General Electric holds several patents on this technology, as do several other companies. In fact, one Japanese company, Matsushita Electric, had a refrigerator on the market four years ago with this type of insulation (the product has since been discontinued). Scientists at Oak Ridge National Laboratory measured the R-value at R-18 per inch.

RSS | Comments | E-mail | Print