Co2, The good,The Bad and your Thoughts,

[supermarketguy]

Hi All,

Now that these systems are in the domain and Having been involved in a few of these installations. I was wondering as you do on a saturday night(especially on valentines night :) )what your experiences have been on these systems.

Also if you have not been invloved in these yet. what views do you have on it, based on what you have heard or information supplied through your companies.

My personal opinion is that in the long term these systems are generaly a good thing and once you get involved in them and are constantly working on them,and understand them they seem to do what they say on the tin. But like everything new it seems a bit daunting at first, as you dont want to make an arse of your self. :o Especially when commissioning one.

This is the way they all want to go, especially as all the retailers have been criticised this week by the enviromental investigation agency as not doing enough to implement these systems into their stores. :(

[750 Valve]

I have had a fair bit to do with these systems over here from an installation, commissioning, service and engineering standpoint (sub-critical only). I must say my overall opinion is very positive. At the end of the day R744 is just another refrigerant, once you understand the implications from a safety standpoint (pressure, leakage and its affects on the human body, etc) it is pretty simple really to grasp.

We were seeing mainly Liquid recirc plants for MT and DX LT off the same plant, due to one major supermarket not being forthcoming with too many new stores of late the focus now is a little more on just DX LT with standard R134a MT and HT racks as is the other major's want. Sometimes (depending on what customer calls for) we run Co2 LT cascade off its own dedicated high stage plant, or incorporate the Co2 LT cascade load onto the two existing MT and HT racks.

From a service standpoint the only issue I forsee is availability of quality Co2. When the sh!t hits the fan and you need 600-700 kgs of R744 it can only really come in a tanker and the availability and turnaround on filling a tanker and getting it to site are a little lacking compared to what we normally expect with refrigerant availability. I urge the use of good quality anhydrous Co2, not necessarily food grade Co2. If food grade must be used ensure you filter it when charging.

Our industry over here is seeing more and more Co2 sub critical which I believe is a good thing, our industry is well versed in the need for training and we have courses available to all. At the end of the day if we can do the same job with relatively little cost difference (compared to traditional) and a whole lot less environmental impact then there is no question really. I understand that financially it may not be available to all customers (it does require some additional costs) but in a supermarket environment the cost of an LT Co2 DX plant is very little in comparison to a R404a one, you just have to be smart how you approach it. The cost of a full liquid recirc plant is more than a standard store but at the end of the day it is up to the customers to reckognise the benefits and be prepared to outlay a lttle more initially.

As the industry moves more and more into R744 the availability of parts and equipment will increase and costs will decrease which will in turn make it an even more viable alternative to a standard store.

[Grizzly]

750 Valve.
I envy you as CO2 is something that I have yet to experience.
Sadly there aren't many if any industrial applications here in the South West.
It's a different thing where the Supermarkets are concerned though as you say.
Been involved in a couple of ground source Heat Pumps though.
Quite interesting in themselves.
Cheers Grizzly

[chillled]

Looked at a couple of plants, just have to bear in mind pressures are higher and use common sense, in morrisons the ht pack(R407a) is used to cool the condenser for the lt (co2) so if you loose the HT games over, guaranteed to happen on a saturday night or bank holiday too!!!!!

[750 Valve]

Looked at a couple of plants, just have to bear in mind pressures are higher and use common sense, in morrisons the ht pack(R407a) is used to cool the condenser for the lt (co2) so if you loose the HT games over, guaranteed to happen on a saturday night or bank holiday too!!!!!

Its always a risk you have to take with sub critical, I wouldn't be surprised to see a few transcritical systems pop up over in the UK.

Grizzly its not all that special, at the end of the day it just makes stuff cold :D

As far as working withg it goes we have a few mechanics you wouldn't let in the door of the plantroom.... for their own safety as much as for the fact they can't even work out a standard DX system on R404a. The DX Co2 LT systems are a bit simpler and most can get their heads around it, its the liquid recirc plants that have them a little bit baffled.

I find a lot of supermarket blokes are too used to be given any faults on a platter - highlighted by a high tech control system, it means their fault finding skills are lacking and they don't often think outside the square. This is the sort of mechanic that will struggle with the Co2 stores or just fumble their way through and hopefully not hurt themselves or anyone else. Thats why you need to go the extra mile (within reason) when designing a system to make sure safety issues are addressed such as no part of the circuit can be isolated (Co2 has a high co-efficient of expansion) or leak detection in all areas that can collect Co2 on a gas leak (plantrooms, coolrooms, etc) or you will end up on the front page of a newspaper and the customers will start to think twice about their direction regarding Co2.

[supermarketguy]

The swing in the uk is mainly towards sub critical systems, but a couple of retailers are trialing transcritical systems.

Only M&S at present are rolling out a consistant programme of Co2 Installations, in conjunction with Oaksmere Design (Consultants).

This will be the way forward to allow all retailers to reduce their enviromental impact and keep the green lobby happy.;)

Which for us as enginneers we had better embrace it, rather than be wary of it and the quicker we get to grips with it the better it will be for all. So the more information that is made available to the engineers on the ground the easier it will be for all to have a understanding when faced with one of these systems.

These systems are still evolving and a system that you may have seen last year, will probably chage the next as they have had a year of field testing and any issues that have been thrown up will be corrected. Such as software and the like.

[Mistral]

I believe that Co2 is here to stay. Most of the larger supermarkets have rolled out a number of installations. Mainly sub-critical. Some are now trying small trans-critical systems. This is the trickier system. There are many types of systems widely installed around Europe. In my experience in design and commissioning of some systems (sub-critical) there is an initial steep learning curve in dealing with the refrigerant and the way it reacts... which is very fast! But it is a fabulous refrigerant and we can really push the bounderies with it. We have seen in supermarkets that we have been able to raise significantly the evaporating temperatures of the plant. The energy savings are there if you design it right.
For service engineers, you need to think differently when on a service call and really be able to think on your feet, cause while CO2 is a very good refrigerant, it will not forgive simple mistakes that one would get away with on a ***** system.

[coolhibby1875]

as 750 valve says there are not that many engineers out there that can think out the off box especially in the supermarket field,Therefore other than M@s in the uk and the odd token install across the other chains (their get out with the tree huggers)i dont think you will see too many chains take it up here in the uk due to the dangers with the systems i think a engineer was killed in Denmark working on c02.
Until the main players i,e WR,Space and the likes can get the majority of their engineering staff fully trained up with the plant and working conditions of co2 then the supermarkets will be reluctant to go whole hog with it.
I can imagine a poor engineer with no training at 3 a.m on a saturday morning having a go at it purly because of the presure put on him at the time by the store manager and when that happens thats when accidents will happen because we will adopt a fridge is just a fridge attitude and start to tinker then BOOM!

[CJG21]

I dot personally think co2 will take off in the current climate as it seems to be very expensive to buy the kit. Obviously this will be the case as new products are always more expensive but I just cant imagine Tesco, Sainsburys or any other retailer really going forward and rolling out a long term project of over half their new installations a year being co2.

Any installtions at the minute seem to be token ones ie Tesco Shrewsbury or the one featured a few months ago in RAC (Cheetham in Manchester I think). In these cases they are installed with the entire store made with energy efficiency in mind and not just co2 systems.

[fowlie]

morrisons are changing to co2 on most refits,these plants are coming and are here to stayi think aolt of engineers are living in hope it doesnt happen but with massive pressure for green systems from green pressure groups and goverments especially E.U meps.we might aswell accept it and embrace these systems,i see co2 plant as great news as this will cut out supermarkets using cowboys to install jobs leaving systms full of leaks and in poor working conditions.also think of the time you can spend on a job by actually writing out a proper risk assesment and following it to the letter no cutting corners for customers or bosses.:)

[750 Valve]

Over here Woolworths are putting in Co2 systems as a norm for new stores (except regional stores) but they have settled for only sub critical LT DX systems, rest of store is R134a. Some exceptionally green sites get sub critical Co2 liquid recirc. Coles have stalled on the Co2 but thats nothing surprising really, they have been a little off target with their store design and generally seem to be flailing a little from an engineering standpoint.

[Silhouette]

Tesco CO2 rollout is on hold whilst the current stores are in energy evaluation for the next 10-12months, then we will see whether they stick with it or go another way!

[fowlie]

i had heard tesco were even looking at using liquid nitrogen and just having boc come in and top up as they think it would be cost effective just to vent it off no need for packs