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US Iceman
15-05-2006, 01:46 AM
Here is an interesting link for those who work on supermarket refrigeration systems or are interested in learning more about the use of CO2.

http://www.linde-refrigeration.com/en/p0002/p0008b/_download/CO2_Sonderdruck_engl.pdf

(1.14 MB)

guapo
15-05-2006, 02:20 AM
Hi US Iceman,

It is good, thanks

Guapo

Carlo Hansen
15-05-2006, 03:03 PM
Hi Us Icemann

It is a realy fine system they has build. But why do they compare co2 with R404A.
It could be interesting to know something about the COP
in this an small co2 systems.
My opinion is that co2 is not a good refrigerant, but maybee I am wrong, does anybody have some experience
with co2.

Best regards
Carlo Hansen

US Iceman
15-05-2006, 09:13 PM
Hi Carlo,


But why do they compare co2 with R404A?

My guess is the comparison was done to R404a since more people are familiar with this than CO2. It might be to provide a comparison from a known value.

CO2 is a good refrigerant, but the shutdown pressures can be quite high. Due to this, hot gas defrost using CO2 can require higher pressure system designs and possibly special components to provide hot gas defrost.

One other issue to be aware of is the triple point of the refrigerant. If a leak develops to atmospheric pressure, the liquid can turn into a solid (dry ice).

CO2 does have some special precautions that are necessary, but it is gaining favor among system designers.

Peter_1
16-05-2006, 06:33 AM
The comparison was also made - I think - because Linde is working mostly in supermarkets and supermarkets mainly use R404a.

I haven't found yet the time to read the whole articlebut how do tyhey prevent ad stand-still the pressure rises too much?

The packs are Bitzers I think and very well made. I also notice that they finally stopped painting their packs in blue.
In the past, there own invented oil system was a real crap. No oil floats, only some sort of orifice to each sump.

Andy
16-05-2006, 08:23 PM
The comparison was also made - I think - because Linde is working mostly in supermarkets and supermarkets mainly use R404a.

I haven't found yet the time to read the whole articlebut how do tyhey prevent ad stand-still the pressure rises too much?

The packs are Bitzers I think and very well made. I also notice that they finally stopped painting their packs in blue.
In the past, there own invented oil system was a real crap. No oil floats, only some sort of orifice to each sump.

Peter:)

Costan still use a similar oil system on their entry level packs:o

Costan also manufacture CO2 Cabinets and Packs, both trans and subcritical (gas cooler and cacade using 404a on the high stage)

I have been told the COP is not that good and the only reason people fit it is enviromental restrictions on refrigerant usage.

Kind Regards. Andy:)

CO2engineer
27-03-2008, 10:10 PM
JS Greenwich has been retrofitted from Care secondary systems to Co2, using Linde/Carrier packs and cabinets.
LT is run subcritical DX condensed by cascade from HT transcritical DX.
All cabinet/cold stores are fitted with Danfoss AKV valves. Any section of the system that can be isolated is fitted with relief valves.
Packs (VS3000C) and cabinets (UA300) controllers are supplied by Eklemann Germany.
For the last 3 months or more power usage has been 40% less than the secondary system.
This store is Sainsbury's flagship so the old enegy usage had been monitored for years and a direct comparison could be made.
By the way if packs are pumped down a small unit run through small heat exchanger means the Co2 charge can remain in the plant for years.

frigeguy
06-04-2008, 02:56 PM
Hello, New to this site. Andy seems to be right there on the CO2 info. I'm sure I'll be looking for all the details I can get. Just had a new CO2 system handed to me. As of yet I have not actually seen it. Ok here goes, CO2 primary, with 404A secondary and gylcol as the third? as it was described to me briefly, the CO2 is going to the cases, the 404A is the secondary stage at the machine room only and the glycol is used to cool the 404A to the roof. I don't have many questions at this time as I have yet to see the building, but i'm sure I will have a few after the first service call. Has anyone seen any similar systems?

NoNickName
06-04-2008, 04:52 PM
Error 404 on the link.

nike123
06-04-2008, 06:00 PM
Error 404 on the link.

It is almost two year old link! That web page is dead.;)
Try to search here, but I doubt you are going to find anything.
http://www.linde-kaeltetechnik.de/?L=1