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Is the cold war really over? Europe makes a breakthrough.

Is the Cold War Really Over? Europe Makes a Breakthrough

Use of polyol esters as lubricants could eliminate the need to scrap existing refrigeration equipment to comply with chlorofluorocarbon ban.

It will be a new millenium nine years from now. But perhaps the millenium has already arrived for the refrigeration industry, threatened with having to replace its equipment to comply with the world ban on chlorofluorocarbons (CFCs) that damage the atmospheric ozone layer.

Research in Europe has confirmed that polyol esters can be used to replace mineral oils in existing refrigeration systems that currently use CFCs but will have to switch to hydrochlorofluorocarbons (HCFCs) or hydrofluorocarbons (HFCs) that aren't compatible with mineral oils.

The breakthrough was heralded early this year in an article in the London Financial Times headlined: "Victory is near in the cold war." But refrigeration experts in the United States were skeptical. Writing for the ASHRAE (American Society of Heating, Refrigeration and Air Conditioning Engineers) Journal, for example, Shelvin Rosen called the alternative lubricants "not suitable . . . in most applications."

But now the British Cold Storage and Distribution Federation has confirmed successful trials of refrigeration equipment using HCFC-polyol ester refrigerant-lubricant blends. "After some 5,000 hours of testing without harmful results, the people concerned remain most optimistic," reported Clive V.J. Dellino of the Federation's technical committee, who looked into the situation at the request of Quick Frozen Foods International.

Both polyol esters and polyalkaline glycols, also suggested for use as lubricants with HCFCs and HFCs, have been criticized as being "hygroscopic" -- that is, having an affinity for water. But the polyol esters now being used in trials are better "by a factor of ten" in this respect than polyalkaline glycols, Dellino found. Moreover, the actual lubricant being used "comes from a pilot plant and is not fully dried." In commercial production, the water content could be reduced from 200 to 800 parts per million to only 40 or 50.

"The suitability of polyol esters for use with other HCFCs and HFCs is confirmed," Dellino went on (the Financial Times report had cited only HFC134a, which it said was being used with a polyol ester developed by Castrol in a new line of home refrigerators manufactured by Electrolux). "This compatability extends to CFCs, and gives rise to the interesting option of |staged' conversion of existing R-12 plants. This would mean that mineral oil lubricants could be replaced with synthetic lubricants during routine maintenance in advance of a refrigerant change."

When the time does come to replace CFCs in existing refrigeration systems, Dellino said, "present indications are that only the gauges and, possibly, expansion valves will need to be replaced." That should bring a sigh of relief to everyone in the refrigeration industry who has been suffering frazzled nerves after learning a few years ago that substitute refrigerants like 134a couldn't be just "dropped in" to existing systems using mineral oil lubricants. For fifty years, the industry has depended on refrigerants miscible with lubricants in a combined system, and it obviously dreaded the prospect of replacing equipment entirely.

Commercial refrigeration isn't entirely out of the woods yet. Many environmentalists are calling for a ban on HCFCs and HFCs, on the grounds that the first also deplete the ozone layer (albeit more slowly) and that the second contribute to global warming. The search may therefore go on for more exotic refrigerants. In the March 1990 issue of the International Journal of Refrigeration, William L. Kopko cited such possibilities as dimethyl ether and cyclopropane compounds. Patterns of toxicity and boiling points are similar to those of CFCs for both classes of chemicals, Kopko noted in summarizing previous research. Since nobody has done any research on lubricants that might be used with such compounds, he had nothing to say on that issue.

Both DuPont in the United States and ICI in Britain are gearing up commercial production of such alternative refrigerants as HFC134a and HCFC22, the latter already being used by Hussman-Craig Nicol for retail refrigerated display cabinets (134a is used only for home refrigerators, automobile air conditioners and the like). According to the Financial Times, "half a dozen other international chemical companies" are also planning to get into the market -- Rhone Poulenc's ISC division already has a pilot plant in the U.K. Castrol, a British lubricants company, also operates in the USA, so the polyol esters it has developed for the refrigeration industry will presumably become available on both sides of the Atlantic.
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Title Annotation:Warehousing World; use of polyol esters as lubricants on refrigeration equipment to comply with chlorofluorocarbon ban
Author:Pierce, J.J.
Publication:Quick Frozen Foods International
Date:Apr 1, 1991
Previous Article:Surprise! European cold store scene overflowing with intervention stocks.
Next Article:Alternative refrigeration systems: much greater efficiency is needed.

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