NIST Industrial Impact

Industry: Air-Conditioning and Refrigeration Institute, Arlington, Virginia
Business: Designing, manufacturing, installing, and maintaining residential and industrial cooling and refrigeration equipment
Size: $20 billion in shipments

In 1937, before a rapt crowd at a meeting of the American Chemical Society, Thomas Midgely, Jr., filled his lungs with vapors of dichlorofluoromethane, the world's first chlorofluorocarbon (CFC)-based refrigerant, and then extinguished a candle as he exhaled. He convinced the audience that this chemical, which he had come up with 7 years earlier at the Dayton Engineering Laboratories Co. (Delco), was neither flammable nor toxic. Had he tried the stunt with the standard refrigerants of the day--ammonia, methyl chloride, and sulfur dioxide--the outcome ultimately would have included some mix of choking, fire, burns, cancer, and death.

CFCs, which became well known under the DuPont trade name Freon, quickly grew into a massive commodity chemical used not only for refrigeration but also for industrial solvents and foaming agents for insulation, cushions, and packing material. When he died in 1944, Midgely had no idea that CFCs already had begun wending their way into the upper atmosphere where they were initiating the destruction of stratospheric ozone molecules, which shield life from dangerous ultraviolet portions of solar radiation. Nor did he know that four decades later the industrial world would agree to cease producing CFCs altogether by 1996 in an effort to stave off the ozone kill.

That dramatic multinational agreement has forced a number of CFC-dependent industries to enter an innovate-for-your-life phase in which they need to come up with CFC substitutes if they expect to remain in business in the next millennium. One of those industries is represented by the Air-Conditioning and Refrigeration Institute (ARI). "We had been using CFCs forever, and now we have to get rid of them on short order," says Mark Menzer, vice president of research and technology for ARI, noting that researchers at the National Institute of Standards and Technology (NIST) are playing a critical supportive role in this
transition.

The challenge resides in the chemical virtuosity of CFCs, save for that fatal flaw of destroying stratospheric ozone molecules.
Before that revelation, CFCs were wonder chemicals--safe, non-toxic, stable, easy to handle, inexpensive, and useful in many ways, including refrigeration. The refrigeration value resides in their ability to undergo countless cycles of volumetric expansion into a gaseous state--during which the CFC gas draws heat from its surroundings such as a refrigerator's interior--and condensation, during which a compressor forces the refrigerant back into the liquid state ready for the next cycle.

Any CFC replacement must come close to matching CFC's virtues while lacking its vices. "We have not found any drop-in
replacements" that can simply take the place of CFCs like one cola for another, Menzer says. HCFCs, in which hydrogen atoms
replace one or more of the chlorine atoms in CFCs, are excellent refrigerants but are not a long-term solution since they too can
destroy ozone molecules; by 2010 at the latest, HCFCs also will be off limits in new equipment.

That has pushed air conditioning and refrigeration companies to look toward more complicated refrigerants, including blends of
two or more components, an exercise that entails redesigning new cooling and refrigeration systems and testing blends for a long
list of physical properties. "We knew we would need data, high-quality data, since small design errors based on the data can lead to big miscalculations" about a cooling unit's efficiency and cost, Menzer explains. Multiply each cooling unit by the many thousands that would be sold and the importance of good engineering data magnifies. That is where data generated and compiled by NIST researchers into a user-friendly personal computer program, called REFPROP, have been coming into the picture of ARI's members. "We have used NIST data and the REFPROP program as the standard," Menzer says.

Soon after the 1987 signing of the Montreal Protocol, which provides for the phaseout of CFCs by 1996, researchers at NIST
began a major effort to measure thermophysical properties of individual environmentally acceptable refrigerants and mixtures involving up to five components. Accurate information about these properties is critical for engineers who aim to design the most
energy-efficient air conditioning and refrigeration systems.

"We have used this information for making important decisions," Menzer says. It has helped companies quickly zero in on blends
worth testing in their engineering labs. "Without NIST, we would have gotten less detailed data, which would have meant a lot more expensive, time-consuming engineering work to produce hardware. It would have cost us millions more." Moreover, he adds, without NIST and REFPROP serving as a common source of data for the industry, each company probably would eventually make different choices about refrigerants, a scenario that would lead to a technical Tower of Babel for the maintenance and repair community. NIST has sold over 500 copies of REFPROP, whose latest version includes data for 38 refrigerants and many of their mixtures.

In a letter to R.F. Kayser, chief of the NIST Thermophysics Division, Donald Bivens, an engineering fellow in DuPont's Fluorochemicals Laboratory, echoed Menzer's assessment of NIST's contribution. "All of this work by NIST has permitted the U.S. refrigeration and air conditioning industry to accurately design equipment for the alternative fluorocarbons, resulting in
efficient operations."

July 1994