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Comment by brilee | Hacker News Reader

HFOs are third generation refrigerants, replacing HFCs, which in turn replaced CFCs.

In 1985, CFCs were recognized as destroying the ozone layer, so they were banned in 1989 and replaced them with HFCs that didn't do that.

The problem with HFCs was that they have 5,000-10,000x greenhouse warming potential relative to CO2. So in 2006 the EU mandated that cars replace HFCs with less potent substances. After 10 years of development and testing, HFOs were finally phased into usage, with most cars using HFOs in their air conditioning.

Heat pumps and HVAC units seem like they're a decade behind autos, but their HFCs should likely be replaced with HFOs, too.

The TFA comes from atmospheric degradation of these HFOs. Scaremongering about TFA without the counterbalancing story of why TFA is showing up and the decades of social, political, and technical work behind HFOs, pisses me off to no end.

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Just use propane. This bullshit with inventing ever more elaborate synthetic compounds which turn out to be toxic has got to stop. We should be denigrating "the decades of social, political, and technical work behind HFOs".

I'm still not convinced propane/butane makes sense in automotive ACs.

EDIT: because it ignites during accidents.

Need to get the operating pressure of CO2 down.

The pressure is intrinsic to the compound. It cannot be lowered.

TIL, thank you!

Many things can ignite during accidents, such as the 10-20 gallons of gasoline in an average automobile tank. The tanks tend to be pretty well protected, and an air-conditioner condensor is normally at the very front end of the car, but that design could be changed.

There's around 3lb of it, around half a gallon equivalent of gasoline.

That's not nothing, but it's not that much that we should be extremely worried - there's around the same amount of fuel in the various lines running from the gas pump to the engine.

It also helps that as a vapor it will dissipate very quickly.

LPG propelled cars exist and are popular in some parts of the world, and it doesn't seem like they're more unsafe than diesel or gasoline equivalents.

I think the future refrigerant for many applications is CO2, with a global warming potential of 1.

Volkswagen put heat pumps with CO2 based refrigerant in their latest cars.

Japanese company Sanden makes components for CO2 based heat pumps and compressors.

https://www.sanden.co.jp/english/products/car/lineup/CO2-Com...

Project Drawdown estimates addressing the emissions of refrigerants to have one of the biggest impacts on climate change.

https://www.drawdown.org/solutions/table-of-solutions

I wonder what is the advantage of those complex compounds (CFCs, HFCs, HFOs) when compared to CO2.

EDIT: Well, duh, answering my questions after a quick search, CO2 liquefies in a much lower pressure than most gases.

In short, the energy efficiency of moving heat depends on the working fluid.

Actually CO2 works very well, but you typically run it in a transcritical cycle where there is a gas cooler instead of a classical condenser unit.

Or, in other words, for using CO2 efficiently on an environment-temperature heat pump, you need it to sustain higher pressures at both the hot and cool sides, and both the pump and nozzle to survive dealing with a higher density fluid that acts in many ways like a liquid.

That explains why people keep searching for a different gas. What is interesting is that it's probably the best gas for that kind of cycle on environment-temperature, as it's too cold for water and amonia, but a low condensing pressure is a benefit here.

Yeah, natural refrigerants are the way - CO2, hydrocarbon gases, ammonia (in industrial settings), water/steam, and air - these can pretty much cover the entire temperature range that you will ever need in heat pumps.

The natural refrigerants are indeed becoming increasingly popular. Essentially all new supermarket refrigeration systems in Europe are CO2-based nowadays, as an example. And almost all domestic fridges are using isobutane, freezers are using isopentane.

Unfortunately there is a large push behind synthetic refrigerants, because there is a large industry who makes money off selling these compounds and would like to keep it that way.

Do refrigeration engineers really fall prey to "big pushes" when everything they need to know about a gas is represented in those charts they use?

kick-backs that produce inter-corporate relationships are vast and numerous.

if X engineer is treated to a real nice dinner and game tickets by Company Y representative , very few charts will sway their opinion.

tl;dr : most corporate products are not shaped purely by economic and efficiency metrics.

Yeah, both companies can easily do that, it doesn't change the balance.

That is corruption.

In general you need to build the whole heat pump (incl. compressor) for the specific refrigerant and application you have in mind.

So if you have an existing line of products using synthetic refrigerants, and a dozen factories around the world making those, you might very well choose to listen to a manufacturer of synthetic refrigerants pushing a new fancy one, rather than decide you need to re-engineer all your products for natural working fluids.

Yeah, I don't really know that much about refrigeration, but that's my take as well. If I had a choice, I'd just run all my stuff with propane, but I don't really know how feasible that is - could I just jury-rig up some hoses and go around charging things? Or are there parts of the system that won't abide by that?

I believe the stated rationale against propane is flammability, but is that really that much of a concern? Presumably you aren't mixing oxygen and propane in the system, so basically you've just got propane lines circulating in your house/car. Big whoop, I've got methane lines in my house already, and the car has plenty of other flammable things too.

> but I don't really know how feasible that is

Only if they run similar pressures. R-22 is basically the same pressure as R-290 (propane) but all the newer stuff is much higher. I think that means it ends up icing over really quick.

A propane/isobutane blend is a good replacement for R-12 which was the refrigerant used for air-conditioning before CFCs were banned. Straight propane as you note is better for freezers than air conditioners.

A problem with blended refrigerants is that if there is a slow leak the blend will change as the refrigerant leaks out, due to the different partial pressures. That makes recharging more difficult, you basically have to vacuum out the system and recharge with the correct mixture.

Also, propane and isobutane are both flammable, but other than CO2, most refrigerants are to some degree.

Some of them produce quite nasty byproducts when they burn too.

Err, my last statement refers to what I think happens if you replaced R410a with R290 without further changes.

Background on refrigerants: The EU bans water-polluting unnatural refrigerants with a high global warming potential,

but water-polluting unnatural refrigerants with low global warming potential (e.g. R1234yf) are unfortunately still permitted for the time being.

Refrigerants from split heatpumps (everything that isn't R290/R744: https://danfoss.com/media/ic5drwy5/gwp-graphic-visual-1120x7... ) endanger water.

Federal Environmental Agency therefore urgently recommends natural refrigerants (R290=propane (monobloc, A+++), R744=CO2): https://twitter.com/Umweltbundesamt/status/13974613677167247...

Please only buy climate&water-protecting heat pumps with natural refrigerants:

Vaillant aroTHERM plus

Viessmann Vitocal 151-A,150-A,250-A,252-A

===============

Also please don't burn wood, it's even more harmful to people & environment than gas (#StopFakeRenewables): https://twitter.com/Umweltbundesamt/status/14917311547639234...

===============

Use cases of natural refrigerants:

- R290 (climate&water-protecting natural refrigerant propane) is perfect for heat pumps and other household devices:

https://www.vaillant.co.uk/homeowners/products/the-arotherm-...

https://live.viessmann.com/en/product-innovations/heat-pump-...

https://www.swegon.com/uk/products/cooling-and-heating/air-c...

https://amazon.de/Royal-Catering-Slush-Eis-Maschine-Arbeitsz...

- Fridges often have R600a (climate&water-protecting natural refrigerant isobutane).

- Carmakers like Volkswagen have switched to R744 (climate&water-protecting natural refrigerant CO2) or intend to.

These are precursors or degradation products for a lot more than refrigerants and propellants.

- Any nonstick or stain resistant coating (scotch guard /Teflon)

- Chemically inert Polymers for fixtures in chemical reactors (more PTFE variations)

Yes, most hvac and refrigeration units are a generation behind, so perhaps the issue will only grow with time. More info: https://appliance.report/gwp/

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