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[akelesis]

hello all

I just came back from the cmx trade show in Toronto and i was talking to one of the salesman at a booth about refrigerants and how its all going to change in the next 5-10 years.

He was mentioning about how in europe. they all have commercial units working off this new refrigerant believe it or not its CO2 and he was saying the pressures that are expected are 2000psig high side and 500 psig on the low side. and they have been using it for years and its a good alternative to our current refrigerants! how does everyone feel about handling pressures as high as 2000psig as a normal commerical unit? it personally kinda scares me but he says it is the new world of refrigeration and we all have to accept it.

heres a link to one of the units kinda cool
http://www.alibaba.com/product-gs/45...tion_Unit.html

[VTP99]

Hydraulic systems have been in use for years and can be as high as 3000 PSI.

[timebuilder]

Hydraulics I have worked on go to 5,000 psi.

To make the unit able to handle such pressures, you would have a radically different kind of containment. My guess is the cost will be impossible below 50 tons.

[jpsmith1cm]

CO2 is nothing new in the refrigeration world.

Nor is it anything new overseas.

CO2 is used as a refrigerant in most of the rest of the world. It is very effective.

Coke and Pepsi are using CO2 in their vending machines and plan to be 100% CO2 in them by 2015 if my memory serves me correctly.

Get used to it, guys. 410a was only the beginning.

[Failure2Comply]

CO2 is nothing new in the refrigeration world.

Nor is it anything new overseas.

CO2 is used as a refrigerant in most of the rest of the world. It is very effective.

Coke and Pepsi are using CO2 in their vending machines and plan to be 100% CO2 in them by 2015 if my memory serves me correctly.

Get used to it, guys. 410a was only the beginning.

I for one will be happy to see it go.

[timebuilder]

I would be interested to see how a CO2 system would be made manifest in a light commercial or residential environment. Specifically, the price point.

[Phase Loss]

I believe Mercedes Benz is using Co2 in mobile A/C systems...I think, but can't remember.

[slctech]

I also maintain and repair CNG and LNG fuel station equipment. Love working on high pressure systems. Newest technology is tungsten carbide bushings with silicon carbide pistons...a set with a piston diameter of 3/8" inch and 5" long can take 150psi in one end and give you 4000 psi at the other...no lubricants, seals, and heat generation is mild but easily dissipated.

Waiting for them to incorporate this technology into CO2 refrigeration compression technology , go from large hermetics and scrolls to a the same compressor a tenth the size and 200% more efficient. Or downsize a hydraulic ram rack to a quarter of the size...we are always the last industry to see incorporation of already proven efficient technology out there.

[Gib's Son]

C02 is where the supermarket industry is going.

[VTP99]

I was using my customers co2 tonight to clean his ice machine coil. He was shocked to see how his rubber line became frozen.

[hvac wiz 79]

C02 is where the supermarket industry is going.

everything must be new yes? or can they retrofit? pardon my ignorance on CO2

[cboe]

I am glad I am retired! you young guys can have it.

[jpsmith1cm]

everything must be new yes? or can they retrofit? pardon my ignorance on CO2

Depends on the type of system.

I would say all new as low temp systems run near 200# suction.

[mark beiser]

The vending machine and automotive systems that use CO2 are transcritical cycles, they don't actually condense the CO2 refrigerant.
Liquid in any part of the cycle would be very very bad for the equipment.

[icemeister]

The vending machine and automotive systems that use CO2 are transcritical cycles, they don't actually condense the CO2 refrigerant.
Liquid in any part of the cycle would be very very bad for the equipment.

This is partly true, since in a transcritical cycle when the heat rejection is done, there is no condensing going on as would be the case in a subcritical system. This is why a transcritical "condenser" is called a gas cooler.

There is a liquid phase present in the transcritical cycle but it occurs after the expansion device during expansion when the pressure drops below the critical point, creating a two phase flow to the evaporator where the liquid is boiled off. The CO2 refrigerant then enters the compressor slightly superheated.

Here's a very good explanation from Danfoss:

http://www.ra.danfoss.com/TechnicalI...0%28CO2%29.pdf

This a video produced by Danfoss which shows CO2 phase changes and also gives a little historical background of CO2 refrigeration, which was first introduced way back in 1850 and peaked in the 1920s.

http://video.google.com/videoplay?do...81612782948466

[mark beiser]

Here's a very good explanation from Danfoss:

http://www.ra.danfoss.com/TechnicalI...0%28CO2%29.pdf

Thanks, that is just a little bit more informative than the 8 year old ACHR News article I was looking at.
For a while I was sort of following how things were playing out in Europe with the vending and automotive CO2 stuff, but never really dug into the details of what is going on at each point in the cycle.

Then I lost interest in it.

[SolarMike]

Many of the fridgies in Europe complain about CO2 systems blowing up in supermarkets, pretty dangerous. Most of the mini-splits over there are CO2 as well as the govt is forcing the phaseout of anything with a high global warming potential.

Most new domestic fridges are Propane also.

[jpsmith1cm]

Many of the fridgies in Europe complain about CO2 systems blowing up in supermarkets, pretty dangerous. Most of the mini-splits over there are CO2 as well as the govt is forcing the phaseout of anything with a high global warming potential.

Most new domestic fridges are Propane also.

The reasons for those blowouts were bad joining procedures.

[SolarMike]

The reasons for those blowouts were bad joining procedures.

Very true....

[coolerik]

We got a few CO2 Supermarkets out this way, but from what I understand they are running a secondary refrigerant (glycol or whatever) would love to learn more about it.. Couple guys on here have some experience with these systems, there is even pictures.. i cant remember where.