NH3 at markets
I'm wondering how many here think ammonia will someday be used as a primary refrigerant in grocery stores? Obviously not for a direct x system, but as a primary to cool some secondary like glycol, co2, or some other secondary refrigerant. I just read an article that it's being "re-classified" and that re classification may make it available for commercial ref in the future. The article was very pro nh3, saying that the primary charge of ammonia at a typical grocery store presented very little threat to public safety due to the (relatively) small amount of ammonia present.
From what I understand, a store was built on this principle last summer.
I know nothing more, though.
I believe every new store will use this before I retire. (probably 30 more years)
There is an Albertsons a little out of my area that is in the finial stages of finishing a store that has a Co2 skid, Mycom NH3 skid, & 407a skid. not sure of the exact setups, but I know they are cascading.
R717 is an awesome refrigerant. The new apps allow its use as long as the NH3 is not inside the occupied space, so an intermediary will be used. I'm thinking that a glycol/h2o mix will be the winner. CO2 has way too tight of a liquid/vapor curve and could easily turn to dry ice if system leaks.....
Ammonia (R717) is a natural (pardon the pun ;)) for the high stage for a cascade system with a CO2.
The main problem areas I see are twofold:
The building and safety codes (and how they're interpreted) can rule out its use in most cases. If you have a very sharp engineer and/or project manager who is knowledgeable and willing to beat the new paths necessary to allow it in residential neighborhoods...let alone within a public building like a supermarket...then you may have a shot.
Then there's the availability of qualified ammonia technicians. Granted, CO2 is no walk in the park for most of us as it's characteristics are a bit foreign, but NH3, while it acts a lot like what we're used to, it is quite toxic and as such, techs must be fully trained, licensed and experienced to work with it.
The store I know about has about has roughly
All skids are on the roof.
They have a separate ammonia contractor when any work is required on the NH3 skid.
There are more techs that can work on 717 than there are on R1234yf. This is the new replacement for 134a...........
They don't like NH3 cuz its cheap and effective. R1234yf is going to cost about 50 buck a pound from what I was told by Emerson. GM will be using it on some of their 2014 production cars.
Also coming soon to a home near you are systems charged with R600 and R290 as the feds ruled that a 'fridge can contain up to 750 grams of it and be acceptable. Hone yer skill gents!
Just out of curiousity...if a rack lost 200lbs of NH3, how great a danger would that pose to people around the store? I know it's heavier than air, but have no perspective about how dangerous it would be.
Hopefully it wouldn't turn into something like this.... http://www.youtube.com/watch?v=sNkdAs1e7Cw
Going out on a limb here, but i'm betting companies like Dupont will oppose use of NH3 for those very reasons.
Originally Posted by Juan Madera
As far as R1234yf goes, if I worked for a car manufacturer I'd *love* a switch to R1234yf. Then, you could force people to take their cars to the dealer for service (which they love) because the "GM authorized dealer" will be the only guy in town with the R1234yf equipment. Sh(@, they'll probably even market the new cars using R1234yf as "Green".
1.) service exposure hazard. Ammonia breaks down rapidly in the environment and it is not toxic, however it is corrosive. It will aggressively attack copper in presence of the slightest amount of moisture. In many places including Canada it requires Class 2.3 Poison Gas placards
2.) Theft. Farms are getting hit by meth cooks for the anhydrous ammonia to use in meth production. Works are in progress to dope the agricultural ammonia to poison meth reaction, but such additives are damaging to refrigeration system.
So... refrigeration grade ammonia pure. Yes, there's been thefts where thieves hit up cold storage plants with bicycle tubes and such releasing tons of NH3. In such a quantity, it leads to community evacuation.
Also, depending on the location of roof top skids, a serious leak from roof top unit can expose the system owner to liability (i.e. blows 500 lbs of NH3 from a 50' roof top and wind blows it into adjacent apartment/office buildings)
NH3 is lighter than air, so it rises, however on a humid day, it will rapidly combine with moisture and form a dense fog(that is highly corrosive to copper and flesh) that will linger for a while.
A snoot full of that stuff will make you run through a brick wall to get away from it. I dont see it ever being around a retail setting for long. A small leak would make people panic that were not used to being around it. It is a great refrigerant.
Earlier I posted about how you would need a pretty sharp engineer to get around the code restrictions concerning NH3 in a supermarket...
Well, I think I found him. :)
Here's an excellent and informative article he wrote about R717 in markets:
He states, among many others things, that there are currently no major code restrictions for its use in supermarkets...with the exception of certain localities where they specifically prohibit it like New Jersey, Chicago and Los Angeles.
It has been recently reclassified by ASHRAE as a B2L refrigerant, meaning it has a lower flammability rating than before.
NH3 is now considered as a safe refrigerant and is currently approved by the EPA's SNAP program.
Now all of this is based on a cascaded or secondary refrigerant system system with the R717 portion housed outdoors, typically as a rooftop package. It's interesting to note that a supermarket is considered as a mixed use facility and as such, the back room and loading docks come under an industrial classification, which would allow for all or part of the ammonia system withing the building.
Still, I think I'd feel more at ease with it all on the roof though. ;)