Cooling That Won't Heat the Globe
The race speeds up to find substitutes for CFCs in refrigerators as ozone depletion accelerates
THE next time you open your refrigerator door for a midnight snack, pause a moment and say, "trichlorofluoromethane."
It may well be a homage to the past. Scientists and environmentalists from more than 80 countries meeting in Copenhagen two weeks ago agreed again to accelerate the phase-out of chlorofluorocarbons (CFCs).
These man-made chemicals in refrigerators, air conditioners, and cleaning solvents contribute to the depletion of the earth's ozone layer, which protects the earth from ultraviolet radiation.
The reason? According to scientists at the meeting, "ozone depletion is significantly worse than in 1990."
CFCs also contribute to the "greenhouse effect" in the lower atmosphere by trapping the sun's heat and other gases such as carbon dioxide. CFCs became popular because they are inert, cheap, and nontoxic.
But as a result of mounting evidence confirming ozone effects, President Bush accelerated a call for an end to the manufacture of CFCs in the United States by the end of 1995. Originally the deadline had been the year 2000. The 74 nations meeting in Copenhagen agreed to meet the same deadline as the United States.
In addition, a ban on the manufacture of halons, a chemical used in fire extinguishers, has been set for Jan. 1, 1994.
In 1892, trichlorofluoromethane became the first man-made CFC, a chemical that mixes chlorine, fluorine, and carbon. Without CFC and its subsequent chemical cousins, refrigerators and air conditioners would not have become the models of cold efficiency and durability that they are today.
FOR the past two years, scientists and corporations have been racing to find a replacement for CFC 12 in refrigerators as well as for a new kind of refrigerator insulation to replace urethane foam.
CFC 11 is used as a blowing agent to puff up the foam. Industry statistics indicate that 7.2 million refrigerators were manufactured last year.
"What appears to be a replacement for CFC 12 is HFC 134a," says Fred Hallett, vice president of industry and government relations for Frigidaire in Annapolis, Md.
Hydrofluorocarbons (HFCs) do not contain chlorine and are expected to break down in the atmosphere.
"We really don't know how persistent 134a will be [in the atmosphere]," he says, "and 134a does require special lubricants [in refrigerators or air conditioners]. We don't know what the performance will be over a long period of time when the two are together, but all the accelerated life tests we have done have indicated they will be satisfactory."
HFC 134a also has some toxicity problems, according to other experts, and it does trap solar heat, thus contributing to the greenhouse effect but not as significantly as CFCs.
According to the United States Environmental Protection Agency (EPA), tests with HFC 134a recently done on rats by an international consortium produced benign tumors.
But Drusilla Hufford of EPA says the tests used massive doses, far beyond anything that would be found in a home. "We think 134a will be safe to use," she concludes.
John Dieckman, manager of the Heating, Ventilating, Air Conditioning and Refrigeration Technology Unit at the consulting firm of Arthur D. Little in Cambridge, Mass., says, "Manufacturers of compressors for home refrigerators have been doing their homework in applying [HFC] 134a to existing compressors and getting favorable results. There is already a sizable production capacity coming on line for the fluid."
The cooling and heating cycle of each refrigerator now made uses six ounces of CFC 12. Pushed by an electric motor, the chemical flows as a vapor through a maze of fat interior tubes and absorbs heat from the refrigerator.
Then it is compressed, sent through thin exterior tubes on the back of the refrigerator, where the heat is drawn off. The cycle is repeated.
IN the stratosphere, the chlorine molecule of CFC 12 damages the ozone layer by destroying as many as 100,000 ozone molecules before it becomes inert. Aerosol cans, now almost all banned, were heavy users of CFC 12.
Aerosols are now a shrinking source of CFCs (see chart).
This year a new supermarket in Glen Falls, N.Y., began using HFC 134a in all of its refrigerator cases and air-conditioners with three different types of compressors to test the results. Many supermarkets leak great amounts of refrigerants monthly.
What manufacturers of refrigerators and freezers remember well is the massive and expensive recall that resulted from a new General Electric (GE) refrigerator compressor in the 1980s. They don't want a repeat.
Under heavy use, many GE compressors failed, indicating that testing had not been thorough enough. GE had to pay out $450 million. "We're being asked to approve a new refrigerant now in a very short time when we had almost 50 years to perfect CFC 12," says a spokesman for a refrigerator manufacturer on the East Coast.
The international science community became so concerned about depletion of the ozone layer that in 1987 representatives formed the Montreal Protocol on Substances That Deplete the Ozone Layer.
At first the countries called for controlling the production of CFCs, then asked for an end to the manufacturing of CFCs when it was learned that both the South and North Poles were experiencing significant erosion of the ozone layer.
Meanwhile, the problem of insulating refrigerators differently could be even tougher to solve than developing a chlorine-free refrigerant. New US efficiency standards will apply to the manufacture of refrigerators beginning Jan. 1, 1993. The Department of Energy has told the refrigerator manufacturers to reduce energy consumption by 25 percent by then.
"There is roughly four times as much CFC 11 [with chlorine] used in a refrigerator than there is CFC 12," says Hallett. "The quickest way to meet these new standards is with better foam insulation.
"But when you find a substitute material and can make it produce good foam," he says, "then you have to adapt the process in the factory that will be compatible with mass production. The quality has to be very uniform."
IN October, Owens-Corning announced a new fiberglass insulation the company carefully called "developmental insulation" and said it had an * value "six times the * value of urethane foam used in today's refrigerator-freezers." * value measures heat insulating capacity.
The insulation would be sealed in a vacuum somewhat like a thermos bottle, and would be formed rigidly to provide structural support in addition to insulation.
Efficiency and environmental safety of refrigerators are critical. Estimates of electrical consumption by refrigerators and freezers in the United States is around 8 percent of the total electricity generated.
"I think the refrigerator of the future will much like the one we have now," says Dieckman. "The combination of compressor and heat exchangers that make up the sealed refrigerator system is a tough act to follow in terms of cost and reliability. How it [improves] without radically changing wall thickness is still an open question."