Wheeler on HVACR: Environmentally-Friendly Substitute?
Well, it was the first time in over 25 years that I've missed the AHR Expo. No, not because I'm afraid of flying, or of terrorists, or because it was held in Atlantic City, but simply because the requirements of my job kept my nose to the old grindstone. I'm doing some temporary writing for McQuay International here in Minneapolis, Minn., during January (Yep, it's cold) and my deadlines won't allow any free time.
I really regret missing attending the exhibition because I'm sure we will see the seeds of some new and great ideas. However, here I am before the show, going over published press releases.
One press release that really piqued my attention advertises a new refrigerant that is supposed to be "an environmentally-friendly drop-in replacement for R-22," the common HCFC that is soon scheduled for phaseout. Could this be? I've been told by all the major refrigerant manufacturers not to look for such a thing. As I was reminded: "We already know all the chemicals and the combinations that are possible, and if we come up with a better, safer, more environmentally-friendly refrigerant, the materials will have to come from another universe."
If you've read my editorials for many years, you know how much I dislike the new HFC (non-chlorinated) refrigerants. The only pure (unblended) HFC refrigerant that can be used for air-conditioning purposes is R-134a , and it really isn't that efficient. It takes much more energy than R-22 to produce the same amount of cooling. The most promising of the blends is R-410a. It's even more efficient than R-22, but its operating pressure requires special piping and compressor shells, and I'm still unsure of how safe the stuff is when riding in a hot service truck.
The other thing I dislike about the new HFCs is the fact that they require the use of new "lubricants" which are extremely vulnerable to moisture, and which can't be mixed with regular refrigerant oils, so they require newly-designed systems. No, they will never be "drop-in replacements" for use with existing equipment.
What bothers me about this product is that it comes from a company I haven't heard of before, ICOR International. (I would have felt better if it came from DuPont, Honeywell, or one of the other well-known players.) Looking them up on the Internet I noticed that there was a recent federal judgment against the company for problems with another product. However, I called up a product specification sheet on the refrigerant they appropriately call NU-22. Pretty impressive.
According to the sheet, the operating pressures, efficiency, and other critical factors are very similar to R-22. The critical temperature is lower, but still usable (194.9F). The exposure limits are the same as R-22 (1,000-ppm), and its Ozone Depletion Factor (ODP) is zero. The best news here is that it can be used with standard refrigerant oils, which means that we can put it into standard air-conditioning systems. Does that mean it's a "drop-in replacement?" It doesn't say. But it comes close to meeting the requirements. It even has an ASHRAE refrigerant number, R-417a.
What is the secret to this blend that makes it miscible with standard refrigerant oils? The comparison numbers seem to have been deliberately made difficult to understand on the specification sheet, but it seems to be heavy on the flammable gas butane. Does that scare me? No, because I'm sure that the blend makes it nonflammable. Several equipment manufacturers have tested their equipment using straight propane and found it quite safe (as well as a good refrigerant), as long as it doesn't leak. A high hydrocarbon content blends well with oil. However, like any blended refrigerant, care must be taken to ensure it doesn't stratify during storage, and the entire charge must be replaced (in the liquid state) whenever there is a refrigerant leak.
I don't know what all the other new product offerings at the AHR Expo will be this year, but R-417a appears to be a major breakthrough and worth our serious consideration. This should be especially true in 2003 when shipments of R-22 are predicted to begin falling short of demand for the first time. That will raise its price and make the easy availability of R-417a look far more attractive, even though it is a much more expensive option at this time.