Five industry experts offered their thoughts during an ASHRAE climate change seminar held during the recent AHR Expo.
RESIDENTIAL A/C
For residential air conditioning, Carrier’s William Walter said R-22 remains refrigerant of choice. Among the non-HCFC options are HFC-407C, HFC-410A, and HC-290 (propane).He acknowledged the need for HFCs to use POE oils and the fact that “A lot of people have problems with POEs as with the moisture question.” But he added, “We need to get over that and become used to them.”
Propane, he said, faces a “flammable hurdle.” He suggested that “the investment to mitigate the risk of fire with HCs would be better spent on building an energy efficient HFC system.”
HFCs do raise concern in some sectors over their Global Warming Potential (GWP). Walter said that currently the refrigerant is part of a “basket” of six so-called greenhouse gases; however, he added that HFCs are not nearly as potentially potent as most others in that basket.
Further, he said that those gases are being judged via a Life Cycle Climate Performance (LCCP) factor. That’s a successor to the more familiar TEWI, he said. And like TEWI, it considers more than just GWP in rating refrigerants.
CHILLER
In the chiller sector, consultant James Calm noted that centrifugals use primarily HCFC-123 as well as HFC-134a. Makers of scroll, piston, and screw units tend to focus on 134a with attention given to HCFC-22, HFC-410A, and HFC-407C in Europe.Adsorption chillers use water and lithium bromide, but Calm called that formulation “not the way to go in terms of global warming” due to lower efficiencies, which in turn require burning of more fossil fuels to power the chillers.
Manufacturers are tackling the efficiency issue in the chiller sector with enhanced O-rings, better sealant, better leak testing, and use of purging with vapor recovery, he said.
In this sector, Calm said, “If we are going to address global warming, we’ve got to improve efficiencies.” This is happening, he said, “but we’ve got a long road ahead.”
When asked about the possibility of trying to save R-123, even though HCFCs are facing phaseout, he said studies have been done to argue for that, but its future remains in doubt.
REFRIGERATION
According to James Lavelle of National Refrigerants, the refrigeration sector looks at refrigerants as a balancing act between what works best in certain applications and the cost to use that refrigerant.HFC-404A and -507 are both good refrigerants in low- and medium-temperature applications, he said. But both cost more than HCFC-22, which also works in both applications. And while 22 faces a phaseout, it may still be available for current equipment depending on how long the owners want it to last.
“If you want the equipment to last 20 years, you’ve got to move away from R-22 now,” he said. “If you want it to last 12 years, you can wait a bit and stay with 22.”
As the manufacturers look to the future, they look at new system designs. Lavelle ticked off some efforts, noting that “As you go down the list, interest on the street lags.”
A well-accepted method involves reducing leakage both in equipment design and through preventive maintenance.
Distributed systems in supermarkets — in which traditional backroom mechanicals are located throughout the store to reduce refrigerant line runs (and thus the amount of refrigerant) — also show potential, he said. But that technology raises questions about increased energy use and service-ability of equipment on the public floor space.
Lavelle lumped such new technologies as secondary loops and using carbon dioxide in the same category as returning to prehistoric “caves of ice.”
HEAT PUMPS
James Crawford of The Trane Company did not speak of specific refrigerants in his talk on heat pumps. Rather, he focused on sources of power for such units as part of the environmental picture.“Those who have natural gas at the curb heat with natural gas,” he said. And since heat pump manufacturers usually also sell furnaces, gas cooling gets the nod.
Yet electricity is “universally available and the safest and easiest to deliver.” Since his talk came during the California energy crisis, he added that electricity is the “easiest to deliver, most of the time.”
The issue gets rather muddled. Hydroelectricity is considered good except that areas behind hydrodams are often muddy and give off methane gas. And then building power plants and transmission lines, not to mention gas pipelines, requires “lots of cement and primary metals.”
MOBILE A/C AND TRANSPORT REFRIGERATION
Engineer Dennis Clodic said most all mobile a/c is using HFC-134a. In transport refrigeration, trucks with belt-and-pulley systems use CFC-12, with a move now toward 134a. For trucks with refrigeration systems independent of the cab motor, 22 and 404A are used.He encouraged leak tightness in this sector. “If nothing is done, we will have rapidly higher emission rates,” perhaps enough to put R-404A in the firing line of environmentalists.
In Europe, he said, transport refrigeration folks are looking at HCs such as propane and carbon dioxide. “Right now that is isolated. But perhaps in the future” such interest will increase.
For more on ASHRAE forums, see pages 35-36. The News will cover forums on motors, ERVs, self-powered heating, and more in upcoming issues.
Publication date: 02/19/2001
