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    More: Interesting, Carbon dioxide, propane-based AC, new research, air-conditioning, one-tenth of electricity, water bottles, Propane systems, journal PNAS  
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1178 clicks; posted to STEM » on 19 Aug 2022 at 7:20 PM (5 weeks ago)   |   Favorite    |   share:  Share on Twitter share via Email Share on Facebook



25 Comments     (+0 »)
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2022-08-19 7:26:07 PM  
KJZZ?  Ewwww!!

Oh, Propane powered AC. Yeah, that makes more sense.
 
2022-08-19 7:27:40 PM  
"Propane systems are already available in China and India, but are barred by some national regulations, mainly due to propane's higher flammability."

All that article needed was an advertisement trying to sell propane AC units branded under the Pinto name.
 
2022-08-19 7:31:31 PM  
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2022-08-19 7:43:30 PM  
They've been using R290 (propane) in commercial refrigeration in the US for a long time now. As rare as refrigerant leaks are there's hardly enough in a typical system to really be a hazard, unless it was all released at once or something.

=Smidge=
 
2022-08-19 7:47:16 PM  

Smidge204: They've been using R290 (propane) in commercial refrigeration in the US for a long time now. As rare as refrigerant leaks are there's hardly enough in a typical system to really be a hazard, unless it was all released at once or something.

=Smidge=


All the salesmen I've heard from really like using a Bic lighter as the example of how much of it is in a commercial refrigerator. It's certainly more than what you'd want to have leak or catch on fire, but not enough to lose sleep over.
 
2022-08-19 8:06:42 PM  

Noticeably F.A.T.: Smidge204: They've been using R290 (propane) in commercial refrigeration in the US for a long time now. As rare as refrigerant leaks are there's hardly enough in a typical system to really be a hazard, unless it was all released at once or something.

=Smidge=

All the salesmen I've heard from really like using a Bic lighter as the example of how much of it is in a commercial refrigerator. It's certainly more than what you'd want to have leak or catch on fire, but not enough to lose sleep over.


Exactly.  I mean, any of the compressed gasses used for an air conditioner are dangerous;  at this point manufacturing is pretty in tune with making something thats inherently dangerous pretty safe, and I can't see an outdoor AC powered by propane being any more dangerous than owning a gas grill.

hell, if its a huge concern, mandate some kind of enclosure that would protect your house & neighbors house from any possible explosion.
 
2022-08-19 8:15:16 PM  
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2022-08-19 8:28:10 PM  
There was an outbreak of propane coolant mini fridge explosions (or explosive like, blowing the door open) several years ago but I can't remember if in the US or the UK.
 
2022-08-19 8:39:58 PM  

Noticeably F.A.T.: Smidge204: They've been using R290 (propane) in commercial refrigeration in the US for a long time now. As rare as refrigerant leaks are there's hardly enough in a typical system to really be a hazard, unless it was all released at once or something.

=Smidge=

All the salesmen I've heard from really like using a Bic lighter as the example of how much of it is in a commercial refrigerator. It's certainly more than what you'd want to have leak or catch on fire, but not enough to lose sleep over.


I believe the lighter uses butane, but that's a minor quibble. Back in the day before Freon was developed, there were refrigeration symptoms that used ammonia. You don't want to be anywhere near a leak of that.
 
2022-08-19 8:44:01 PM  
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2022-08-19 8:46:27 PM  

revrendjim: Noticeably F.A.T.: Smidge204: They've been using R290 (propane) in commercial refrigeration in the US for a long time now. As rare as refrigerant leaks are there's hardly enough in a typical system to really be a hazard, unless it was all released at once or something.

=Smidge=

All the salesmen I've heard from really like using a Bic lighter as the example of how much of it is in a commercial refrigerator. It's certainly more than what you'd want to have leak or catch on fire, but not enough to lose sleep over.

I believe the lighter uses butane, but that's a minor quibble. Back in the day before Freon was developed, there were refrigeration symptoms that used ammonia. You don't want to be anywhere near a leak of that.


It does, but it was more of a "here's how much flammable stuff is going to be in your kitchen" example.
 
2022-08-19 9:03:28 PM  

revrendjim: Noticeably F.A.T.: Smidge204: They've been using R290 (propane) in commercial refrigeration in the US for a long time now. As rare as refrigerant leaks are there's hardly enough in a typical system to really be a hazard, unless it was all released at once or something.

=Smidge=

All the salesmen I've heard from really like using a Bic lighter as the example of how much of it is in a commercial refrigerator. It's certainly more than what you'd want to have leak or catch on fire, but not enough to lose sleep over.

I believe the lighter uses butane, but that's a minor quibble. Back in the day before Freon was developed, there were refrigeration symptoms that used ammonia. You don't want to be anywhere near a leak of that.


A lot of grocery store systems are ammonia. It scales up a lot better than other refrigerants.
 
2022-08-19 9:11:40 PM  
Switching to CO2 (R744) is probably a better idea.
 
2022-08-19 9:14:07 PM  

Smidge204: They've been using R290 (propane) in commercial refrigeration in the US for a long time now


I've been doing it for over a decade as a drop-in replacement for automotive AC filling. I've got a set of hoses that I've rigged up to use a BBQ bottle for quick and fast refills. It works great for people I know who have auto AC with small leaks - the kind not worth taking a bunch of stuff apart to find or replace, but the kind where a fill of refrigerant in March lasts through September or maybe a little top-off in the middle of summer also gets the job done.
 
2022-08-19 9:32:25 PM  
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Most meta thing ever
 
2022-08-19 9:32:33 PM  

revrendjim: Noticeably F.A.T.: Smidge204: They've been using R290 (propane) in commercial refrigeration in the US for a long time now. As rare as refrigerant leaks are there's hardly enough in a typical system to really be a hazard, unless it was all released at once or something.

=Smidge=

All the salesmen I've heard from really like using a Bic lighter as the example of how much of it is in a commercial refrigerator. It's certainly more than what you'd want to have leak or catch on fire, but not enough to lose sleep over.

I believe the lighter uses butane, but that's a minor quibble. Back in the day before Freon was developed, there were refrigeration symptoms that used ammonia. You don't want to be anywhere near a leak of that.


I worked at a food distro with a commercial freezer that used ammonia. We had drills in case a line broke that amounted to fleeing as fast as you can and don't look back.
 
2022-08-19 9:44:11 PM  
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2022-08-19 11:52:44 PM  

Ecliptic: A lot of grocery store systems are ammonia. It scales up a lot better than other refrigerants.


It's also a standard industrial chemical used in a lot of other processes and thus manufactured in absurdly massive quantities that can easily be skimmed for smaller-volume uses like refrigeration and cleaning products, so you can in this case translate "scales up" to "is cheap".

Propane is... not a bad idea, honestly.  It's not particularly toxic, not heavy enough to stick or linger if it leaks, is chemically active enough to degrade after release in a way that doesn't produce materials that are toxic, and it similarly relatively cheap to manufacture even if it can't be trivially refined from a natural source of hydrocarbons.  Freon and a lot of the large-molecule refrigerants have better compression characteristics for the purpose but in terms of overall design "just build a bigger refrigeration loop if it's less efficient" is a pretty good trade-off for the kinds of air units that are, y'know, bolted to the ground and don't move.

// A lot of said specialized refrigerants fall into the category of "actual HAZMAT shiat, putting it in the normal trash/junkyard is a high-grade misdemeanor or minor felony".  They're almost universally pretty directly poisonous in relevant concentration, not just bad for the atmosphere.  Propane would still have a hazard symbol, it'd just be in a different color and could be disposed of with a valve and a pilot light.

// Ammonia is actually the literal textbook chemical for heat-pump design, the temperature-entropy phase curve is insanely friendly to the basic idea for reasons related to degrees of freedom in the liquid and gas phases respectively.  It's actually better than most of the more specialized chemicals for the heat-pump itself, the reason everyone switched to freon etc was mostly about safety.  Ammonia isn't just super acutely toxic when it leaks, it's one of the most corrosive substances that you're ever likely to encounter outside of an actual career as a chemist and tends to erode the equipment it's flowing through really quickly, especially if there are even minor flaws in protective plating etc.  Not a big deal in a large commercial setting where you have on-staff techs doing regular scheduled inspections of all parts of the system, but you can probably figure out how that tended to work out in smaller systems managed by individual renters and homeowners who only call out techs when they notice something is wrong without me having to describe it in further detail.
 
2022-08-20 12:08:21 AM  
I replaced the AC compressor in my car a few years ago, and charged it with R290 (refrigerant grade propane). Works like a champ, and waaaay cheaper than taking it to the stealership. I think I read that in an automotive application, propane will actually give you better results. All AC lines are in front of the firewall, so I'm not really concerned about it.

/did it right, vacuum pump, manifold, etc
//new compressor, filter, dryer
///brrrrr
 
2022-08-20 12:19:38 AM  

Bourbonman: Works like a champ, and waaaay cheaper than taking it to the stealership. I think I read that in an automotive application, propane will actually give you better results.


1,000% yes, in all R12 or R124 applications you can substitute R290 and get equal or better performance.
 
2022-08-20 12:44:31 AM  

mrmopar5287: Switching to CO2 (R744) is probably a better idea.


CO2 is already in use in some places, but no thanks, at 42f (AC evaporator pressures) R744 (CO2) is at 569psig compared to R410A at 123psig, R22 = 71PSIG, and R290 (Propane) = 67psig.
Now lets talk condenser pressure, The AC's I work on run condensers around 120F to 130F this time of year; so as a basis use 125F, CO2 = 1835psig, R410A = 447psig, R22 = 278psig, and R290 = 243psig.
All pressures (rounded) are from the Danfoss Ref Tool App.

As many times as I've seen poorly brazed pipes come apart when pressure testing. Honestly I don't trust most AC guys to safely put together or service a CO2 refrigerant circuit without something going wrong at those pressures. I don't see wide spread adoption in the US for liability reasons. And where used limited to specialized industrial and rare to never for residential or light commercial
Not to mention recovering R410A in summer is hard enough, can't imagine trying to recover CO2. You'd have to bury the recovery cylinder in dry ice.

Most modern proposals I've seen for propane AC units use a glycol loop to transfer heat in/out of the home. This eliminates the worry of a propane leak in a living space. The actual heat pump circuit containing propane can be placed away from a home. Plus a glycol loop can connect to a central system, split system, or radiant. Build one with with a variable inverter compressor it would be highly efficient.
As far as danger;  How many people worry about the propane grill on the patio exploding? Or the big residential propane tanks? It doesn't really happen, propane bottles have safety's that open when over-pressure to prevent explosions and the gas burns off. Same thing can be done for propane AC systems.
Plus cost is becoming a real issue. Last time I looked R410A(25lb) was up to $500 a bottle wholesale and R22(30lb) was $1500+ a bottle. and Propane R290(20lb) is about $200.
As a plus a leak checks are so much quicker and easier, just wave a lighter around where you think the leak is. No messy leak detect solution, no iffy electronic leak detector, no eyebrows... You know someone has done or will do it at some point.
Also, when propane burns it doesn't break down into a nasty acid, unlike fluorocarbons.

Residential ammonia cooling units were a thing in the 80's, the natural gas companies sold them since the absorption refrigeration cycle is driven by a heat source. My mentor in the AC world removed hundreds in DFW area the late 80's due to continuous issues with leaks and no contractors wiling to work on them. Ammonia is corrosive to copper, so requires stainless steel piping which is cost prohibitive for residential.
Many RV refrigerators still run on ammonia absorption cycle and there are ammonia off-grid refrigerators that run by a propane heater.
About a 15yrs ago a guy in Austin, TX tried to sell a residential ammonia system using rooftop solar thermal as the heat source during the day. He had the same issues with leaks and contractors not willing to work on them.
I've never worked with ammonia, but have been told leaks are a very common hazard.
 
2022-08-20 1:20:00 AM  

TX_Sarcassim: Not to mention recovering R410A in summer is hard enough, can't imagine trying to recover CO2.


Nobody would do that. Vent it and fill with fresh gas.
 
2022-08-20 5:51:45 AM  

Ecliptic: A lot of grocery store systems are ammonia. It scales up a lot better than other refrigerants.


The stuff you buy at the grocery store might *contain* ammonia, but it's not ammonia like what's used in older refrigerant systems. "Clear Ammonia" is what they sell, which is a 10% solution of ammonium hydroxide in water (and sometimes surfactants since it's sold as a cleaning agent)

Refrigerant uses pure liquid ammonia. The only other uses for pure ammonia I can think of are fertilizer, textiles, and explosives manufacturing. Not great stuff to get exposed to.
=Smidge=
 
2022-08-20 10:44:35 AM  

Smidge204: Ecliptic: A lot of grocery store systems are ammonia. It scales up a lot better than other refrigerants.

The stuff you buy at the grocery store might *contain* ammonia, but it's not ammonia like what's used in older refrigerant systems. "Clear Ammonia" is what they sell, which is a 10% solution of ammonium hydroxide in water (and sometimes surfactants since it's sold as a cleaning agent)

Refrigerant uses pure liquid ammonia. The only other uses for pure ammonia I can think of are fertilizer, textiles, and explosives manufacturing. Not great stuff to get exposed to.
=Smidge=


I assume he's talking about the systems which keep the freezer aisles frozen at the grocery store, not the little bottles on the shelf.

And it is the same ammonia in both cases, just more of it. When you open the bottle of cleaning solution, the little whiff of gas you smell is the same chemical that's used to chill your local hockey rink. As a pure substance, it's only liquid at very low temperature or under high pressure. Therefore when the system springs a leak, your building quickly fills with toxic gas. It's nasty but it is an excellent refrigerant.
 
2022-08-20 10:48:50 AM  

Ivo Shandor: TX_Sarcassim: Not to mention recovering R410A in summer is hard enough, can't imagine trying to recover CO2.

Nobody would do that. Vent it and fill with fresh gas.


EPA regs..around here if they didn't turn in the recovered gas they would be in deep doodoo.  Not a tech, just have them work on my stuff. The posters CO2 example was funny tho "bury the recovery cylinder in dry ice", which sublimates...so you're releasing a lot more CO2 than you're recovering. Idk if CO2 even needs to be recovered or they're making a joke. Main hazards I would think are the fluorocarbons.
 
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