Co2

[750 Valve]

I know Co2 was used years ago and is used today on industrial plants but has anybody worked on, designed, heard of or have seen any commercial plants using carbon dioxide as a low stage refrigerant on say a supermarket or small to medium coldstore?

My company is currently tossing up the idea of trialling a low temp rack on Co2 , approx 70 to 80 KW, -30 deg C SST, -10 deg C SCT using med temp rack as high stage/heat exchanger.
Theres gotta be a few out there already, what are the pros and cons?
It'll be weird to have a system that increases pressure on the hi side when it shuts down. Apparently we are looking at about one sixth the plant size than on R404a, thats gotta be some $$$ savings. Was thinking we should run it off the high temp rack and use -10 deg C liquid and pump it to our med temp cases, save more on refrigerant seeing we were quoted $5 per Kg for (not sure if this is correct) anhydrous medical Co2?!? You could even have propylene glycol pumped to med temp cases and CO2 heat exchanger, refrigerated by high temp rack... If you wanted to stock every fluid known to man.

[Peter_1]

I have somewhere literature in a Dutch refrigeration magazine where they describe a setup of a small CO2 plant for a supermarket. I think it was for the groep Albert Hein. Unfortunately, the article will be written in Dutch.
They used it in the 1st circuit which cooled glycol for the 2nd circuit. I don't know what kind of compressor you have to use but I don't think you can use anything of the standard stuff.

http://www.ahold.com/aholdinsociety/operations/refrigeration.asp gives some common information, not technical.
I think it was the Cpy GTI ( www.gti-group.com )who did the installation.
Peter

[750 Valve]

Bitzer now manufacture compressors for CO2, and I've seen a Danfoss TUAE valve with a CO2 power element charge, soon to be available as well

[Peter_1]

Have a look tpage 23 to 28 of
http://www.student.unimelb.edu.au/~chaic/bitzer_report_9.pdf

[Argus]

Sounds like a PED nightmare..........!
________
amber trichomes (http://trichomes.org)

[kiwi001]

I have come across a two stage CO2 supermarket trialled in denmark approx 3 years ago. I have also seen light commercial applications trialled using CO2. I belive Sanyo and Danfoss are both building CO2 compressors.

[norcool]

Hey,my company have done a lot off works with CO2,compressor developements,valves,also for RAC-plants,infact there are still som problems
with lubrication system for fast revolving CO2 compr.
For the aircondition in vehicles we are more satisfied .Standard CO2 plant
could easily be better if you use gascooler ex(produce hotwater) before
condenser.We also have been testing 2-stage transcritical prosess it seems
to give a good COP compared to 404/410.
hilsen gunnar.lohse@energy.sintef.no.