CHANGING REFRIGERANTS 2004-09-13 (2)

JULIE GALLAGHER

Supermarkets continue to be in the thick of the debate over the environment.

It all stems from an international agreement among industrialized nations, the Montreal Protocol, to stop the use of ozone-depleting chemicals. As part of that agreement, the United States is obligated to make progress toward a total phaseout of refrigerants used by supermarkets, such as CFCs (chlorofluorocarbons), including Freon, and HCFCs (hydrochlorofluorocarbons), including the refrigerant R-22.

As of Jan. 1, 2010, U.S. chemical manufacturers may still produce the refrigerants to service existing equipment, but they must cease production for use with new equipment. As of Jan. 1, 2030, the production and importing of HCFCs must cease entirely, said the U.S. Environmental Protection Agency.

Although the mandate will not affect retailers for years, many supermarkets have already begun retrofitting their existing refrigeration systems with an environment-friendly refrigerant, in particular, the less-regulated HFC (hydrofluorocarbons), R-404a, which doesn't contain ozone-depleting chlorine.

R-404a can also improve the energy intake and cooling capacity of existing systems, but it is more expensive than its predecessors. Upgrading to a new refrigerant also poses a host of technical challenges.

Alternative refrigerants will be one of the key topics addressed this week at Food Marketing Institute's 25th annual Energy & Technical Services Conference. The conference, scheduled for Sept. 12 to 15, will take place at The Adolphus in Dallas. Ed Estberg, senior director of facilities, Raley's Supermarkets, Sacramento, Calif., will describe how his chain converted its systems from R-22 to R-404a.

The higher cost of R-404a has not been a deterrent to Giant Eagle, Pittsburgh. "Although the cost of R-404a is much greater than that of R-22, Giant Eagle uses ozone-friendly refrigerants because it is the right thing to do," said Cliff Timko, energy manager for Giant Eagle. "As a supermarket retailer, we always want our customers to see us as good environmental stewards, and provide customers and employees with a safe and environmentally friendly atmosphere in which to shop and work."

Like many food retailers, Giant Eagle has gone through several refrigerants over time. The chain began using R-22 in its medium-refrigeration system and CFC refrigerant in its low-temperature equipment. After the Clean Air Act became law in 1990, a production phaseout of all CFCs was required. The retailer decided to replace the previously used CFC with R-22 refrigerant in its low-temperature equipment.

Then, after testing R-404a, Giant Eagle decided the efficiency gains associated with making the change from R-22 to R-404a, along with the environmental benefits, justified its implementation, according to Timko.

Not So Simple

Although the process seems as if it might be as easy as changing the oil in one's car, such switches often cost tens of thousands of dollars and require the reengineering of an existing refrigeration system by its manufacturer, according to Mark Harbin, manager of compliance services for Environmental Support Services (ESS), Tempe, Ariz.

"You can't just drain a refrigerant and put in a new one. It's usually a lot more complicated than that," he explained. "Gaskets 'remember' the molecular structure of the previously used refrigerant and the way it behaved. You have to flush the oil and do some engineering to retrofit an ozone-safe refrigerant into a system that previously accepted a different type of refrigerant."

Part of the process involves a manufacturer-executed engineering run performed to monitor changes associated with use of a new refrigerant in an existing system. "Sometimes the change is not significant, but there is usually [performance change]," explained Harbin, who said system performance could be degraded or enhanced, depending on the existing refrigeration system and the refrigerant used.

Timko noted that when Giant Eagle migrated from CFC-502 to R-22, system modifications were required to protect the compressors of its refrigeration system from the high discharge temperatures that are associated with R-22. "The [R-22] charged compressors resulted in reduced capacity and efficiency and an increased failure rate," explained Timko. "[Luckily,] most of the capacity and efficiency losses resulting in making that switch were eliminated when we moved [from R-22] to R-404a."

Although Giant Eagle experienced some valve plate and compressor failures with some R-404a compressors early in the refrigerant's use, the compressor's manufacturer corrected the problem by redesigning the valve plates and eventually the entire compressor. "With this new design, the failure rate is back to normal for this compressor," said Timko.

Giant Eagle has also installed leak-resistant components in its refrigeration system to prevent refrigerant leakage that can occur from stress cracks and seal failure due to wear and tear. "All systems are tested under pressure before being charged with refrigerant," said Timko. "The systems and the store are then continuously monitored using an infrared leak detector, which alerts the store and the servicing contractor if a leak is sensed."

Although the retailer is proactive in preventing leakage, HFCs, including R-404a, are not regulated under the leak rate and repair rules that HCFCs like R-22 are subject to, according to Harbin.

"Once an organization converts to an HFC, they've moved to a less-regulated area," he explained. "There are no leak requirements [with HFCs], and their leak rates don't have to be tracked. A less-regulated refrigerant gives [a retailer] more time and the option of not doing a leak repair if it is minor."

Still, HFC is regulated in the sense that, in 1995, it became illegal to vent all substitute refrigerants (those other than chlorine-based), according to Harbin. Because of this, he strongly advised supermarkets to document all refrigerant-related service, installations and disposals. Also, he warned that even HFC refrigerants like R-404a are harmful to humans because they displace oxygen.

Though HFCs are not currently regulated, the EPA has proposed rules changes, still pending, that would regulate them.

Minneapolis-based Supervalu also takes leak detections seriously, despite its use of the less-regulated HFC, R-404a. The retailer uses R-404a in the refrigeration systems at its new stores.

"There are so many places that leaks can take place," said Neil Monson, manager of refrigeration engineering at Supervalu. "We have tight processes and procedures in place to check for potential leaks before the refrigerant is even in the system."

An infrared detector helps the retailer to monitor for leaks once refrigerant is added to a refrigeration system. The infrared detector "monitors our mechanical center and other strategic locations," said Don Lorimier, director of retail facilities and engineering, Supervalu. "It uses sensors that can pick up on a leak when it occurs so that we can react to it immediately."

Another system that can help cut down on leaks as well as the reduce the amount of refrigerant used by up to 70% has been introduced by Hill Phoenix, Conyers, Ga. Called Second Nature, this secondary coolant system employs low-pressure propylene glycol that enables the coils to work more efficiently.

Howard Adkins, president of Howard's Market, Boca Raton, Fla., said he is surprised that mainstream supermarkets have been slow to adopt new products like the Second Nature system. Adkins said Howard's implemented Second Nature in July 2003, and the results have been impressive. "In addition to meeting our style requirements, we have been able to achieve energy savings with this cutting-edge technology and have saved on installation as well," he stated.

New Cooling Technologies

Although R-404a is more ozone-friendly than its chlorine-containing counterparts, the refrigerant does have an environmental downside -- the potential to cause global warming, observers said. As a result, efforts are under way to develop alternative technologies that can generate refrigeration primarily without chemicals.

For example, Burlington, Vt.-based ice cream maker Ben & Jerry's has been working with Pennsylvania State University and Unilever on a prototype of a thermo-acoustic refrigeration technology, which uses sound waves instead of chemical substances to generate cooling.

"The thermo-acoustic refrigeration process has many benefits," said Steven Garrett, senior scientist and professor of acoustics at Penn State, in a statement. "We can eliminate a lot of mechanical equipment in a refrigerator, allowing for less maintenance and better temperature control, as well as a potentially more efficient and compact refrigerator. But the real benefit is the use of naturally occurring inert gases, which is the key to long-term environmental changes."

Meanwhile, although it's not yet available for commercial use, a magnetic refrigerator has been developed by Milwaukee-based Astronautics Corp. of America as part of a cooperative research and development agreement made with the U.S. Department of Energy's Ames Laboratory, Ames, Iowa.

Instead of relying on a refrigerant and compressors like conventional refrigerators do, magnetic refrigeration is based on what is known as a magnetocaloric effect. It is the ability of some materials to heat up when magnetized and cool when removed from the magnetic field. In this case, the refrigerator employs a wheel containing segments of gadolinium powder, an earth-permanent magnet and a system of water pumps.

"The permanent magnets and the gadolinium don't require any energy inputs to make them work," said Karl Gschneidner Jr., senior metallurgist, Ames Laboratory, in a statement. "The only energy it takes is the electricity for the motors to spin the wheel and drive the water pumps."