[supers05]

Charged a trainer this past weekend. Ran it and went though a bunch of specific details about CO2. Namely the biggest are:
- Higher pressure then R410A. Low side from below 300psig to 500psig. (high side 410 gauges work for the low side) High side 900-1100psig. Special gauge required.
- Triple point at -60*F / 60PSIA. Vapour charge to above 100psig. Be careful of reliefs, as outlet piping is not allowed.
- relatively efficient below 87*F
- make sure there's enough room for expansion during standby.(fade out tank) (or a secondary cooler for the receiver on large systems)

Yes that really is solid CO2.

Cheers

 

[yuri]

AKA: dry ice.:wink2:

 

[user_12345a]

(high side 410 gauges work for the low side) High side 900-1100psig. Special gauge required.

man that must be dangerous. environmentally benign, well at least until they try to ban co2 refrigerant due to global warming while ignoring the all the co2 produced to generate the electricity to run the machine.

 

[supers05]

man that must be dangerous. environmentally benign, well at least until they try to ban co2 refrigerant due to global warming while ignoring the all the co2 produced to generate the electricity to run the machine.

The pressures aren't terribly new. Apparently CO2 was the refrigerant of choice in the 1920-30s. Since R410A has 1000x the greenhouse effect as CO2, it's a great benefit.

Cheers!

 

[raylo32]

Exactly. Also no chance of CO2 being bannned since new CO2 would not need to be made, you'd just capture and use existing hence a net zero impact. However the fact the no new CO2 would need to be made (and therefore profited from) probably makes this a non starter with the corporate influence in our govt.

The pressures aren't terribly new. Apparently CO2 was the refrigerant of choice in the 1920-30s. Since R410A has 1000x the greenhouse effect as CO2, it's a great benefit.

Cheers!

 

[user_12345a]

what kind of oil is it compatible with?

does it carry oil like the chemical refrigerants do?

they used to use all sorts of dangerous stuff like ammonia, sulfur dioxide in the old days.

would wonder if they need to use thicker pipes, etc for the pressures.

guess you could top off and vent co2 with relatively little environmental damage.

 

[Bret86844]

I recently sat through a lunch n learn on this. I guess it works well in the grocery industry for coolers. It's growing in Europe and gaining traction here. Not great for comport cooling apparently.

 

[ChuckF.]

Exactly. Also no chance of CO2 being bannned since new CO2 would not need to be made, you'd just capture and use existing hence a net zero impact. However the fact the no new CO2 would need to be made (and therefore profited from) probably makes this a non starter with the corporate influence in our govt.

DuPont can't patent CO2! How are they supposed to make a living?

 

[supers05]

what kind of oil is it compatible with?

does it carry oil like the chemical refrigerants do?

they used to use all sorts of dangerous stuff like ammonia, sulfur dioxide in the old days.

would wonder if they need to use thicker pipes, etc for the pressures.

guess you could top off and vent co2 with relatively little environmental damage.

PoE.

It is a better solvent then R410A. They do take precautions to prevent the oil from getting washed off the bearings though. (run it though a superheater heat exchanger before the compressor.)

It has been used in heat pump applications. Particularly heavily used in Japanese hot water heaters.

Condensating temps above 87 makes it go trans-critical which causes the efficiency to take a small dive. (still better then the old common r22 systems though) Below this, it's not efficient then r410a.

It's useful for supermarket refrigeration because of the insanely small piping, and expensive alternative refrigerants. Some chains are even storing entire auxiliary charges onsite due to the low price of CO2.

At the moment, no one is recovering it. It's just released, and a new charge added.


High side needs to be rated for the pressures. (reliefs blow at 1600psi) However, because they can use smaller tubes, copper can still be used. Often, anything over 1/4" would be Stainless Steel. There are some companies working to have their copper certified though.

Copper to Stainless header of the condenser/ gas cooler.

On the low side, it's standard off the shelf parts. In that trainer, they have the medium temp trans-critical compressor, and the low temp sub-critical compressor. The HT compressor has a thinker wall construction. The LT is almost a standard off the shelf scroll. (slight modifications for the change in density of CO2)

They had it decked out in nice controls. Had VFDs, and EEVs. Walk-in coolers wouldn't have any of this, and only one compressor in the condensing unit.

Cheers!

 

[user_12345a]

good info - nice pics too.

 

[user_12345a]

DuPont can't patent CO2! How are they supposed to make a living?

Not sure of the if co2 is dangerous as a refrigerant, but the chemical companies will use the fear of high pressures continue to push their refrigerants, give co2 a lot of bad press.

 

[beenthere]

Biggest concern is a leak in the system putting CO2 into the home or occupied space.

https://www.kane.co.uk/knowledge-centre/what-are-safe-levels-of-co-and-co2-in-rooms

At .1%/1000PPM, a person will start feeling the effects.

 

[supers05]

Not sure of the if co2 is dangerous as a refrigerant, but the chemical companies will use the fear of high pressures continue to push their refrigerants, give co2 a lot of bad press.

Nothing new.

Refrigerants already are compared against a toxicity level of 400ppm. If it's above that, it's considered safe. It's comparable to r410a.

The funny part is that we wrap and seal our buildings, to the point of requiring mechanical fresh air. CO2 levels already are monitored in large buildings, which open econo dampers and turn on exhaust fans. Or bodies can produce enough CO2 for the air to become toxic within hours when the conditions are right. Fear mongering will be difficult.

Cheers!

 

[yuri]

Ammonia NH3 is still used a LOT. Huge meat or fish processing/packing plants etc use tons of it.

Cannot be used where the public is but for industrial refrigeration it is the King.


http://industrialrefrigeration.danfoss.com/refrigerants/ammonia/#

 

[user_12345a]

Fear mongering will be difficult.

They'll get it done - marketing spin.

They don't care about toxicity of their own refrigerants though.