[innovator]

Defrost

The only thing I would say is that when defrosting the coils the heaters are on the same amount of time as a typical DX system, but your pump down and drip time are longer than a DX system. And with CO2 the defrost termination temp is the same as with DX.

I have been shown the savings from comparing compressor run time cost vs. electric heater cost and reduced number of defrosts per day not to mention reduced maint cost and the numbers favor electric over gas. And by the way, a great advocate (they were one of the first) of the Co2 system is Linde of Europe. They have info on their site, takes some digging though
linde.com

 

[kooltek]

What type of liquid CO2 pumps are used and how is the fixture temperature controlled? I work in the Industrial sector using liquid recirculation systems with R134a. Are the liquid pumps similar? I would think that Wegmans would be a good candidate for this CO2 system since they are big users of Second Nature med temp glycol systems.

 

[smilies]

I still want to check one out, I may have to go to Georgia!

 

[eng&tech]

Temperature in the case is controlled by a temp sensor in the discharge air, when the case air temp is at set point the rack controller shuts off the case's liquid line solenoild, as the temp raise the LLS is opened. The pump is a liquid pump simular to the pump used on a regular secondary system.

You dont have to travel to Georiga to see one, one started up in VA about a month ago at a Food Lion. With the price of refrigerant at $7-$8 a pound we are all going to see one sooner or later.

 

[smilies]

You dont have to travel to Georiga to see one, one started up in VA about a month ago at a Food Lion. With the price of refrigerant at $7-$8 a pound we are all going to see one sooner or later.

Why are you sending me further away? I'm in Phoenix

 

[stanbyyourword]

hi i also have some interest in this tech., is the refrigeration plant smaller than typical rack setup, being a centralized package? ie hp/kw less overall capacity/demand to maintian co2? etc and also not clear on type of pump used , deffinitely high pressure , similar to industrial refrigerant pump? regards stan

 

[joker1022]

C02 Locations

FYI, Kysor is in the Co2 game now as well. Food Lion has another store that we are presently starting up in College Park, GA. Cool stuff.

 

[teddy bear]

What is the discharge temperature and pressure of a CO2 compressor on a 80^F day? Regards TB

 

[eng&tech]

Discharge pressure on the HP rack will run about 400-420psig, regardless of ambient. These system are not trans-crittical system. Condensing is done at about 20^F. Pressure on the CO2 racks in the USA will be simular to those of 410A. I think by the end of the year Food Lion will have 4 CO2 systems running. What's really kool is the Kysor rack and the Hill rack that is being installed right now are both med temp and low temp CO2@ .50 cent a pound!!!

 

[teddy bear]

Discharge pressure on the HP rack will run about 400-420psig, regardless of ambient. These system are not trans-crittical system. Condensing is done at about 20^F. Pressure on the CO2 racks in the USA will be simular to those of 410A. I think by the end of the year Food Lion will have 4 CO2 systems running. What's really kool is the Kysor rack and the Hill rack that is being installed right now are both med temp and low temp CO2@ .50 cent a pound!!!

Will Food Loin include hot water reclaim as part of system?
Regards TB

 

[eng&tech]

The HP will have heat recalim both potable water and air reclaim

 

[pherman]

Discharge pressure on the HP rack will run about 400-420psig, regardless of ambient. These system are not trans-crittical system. Condensing is done at about 20^F. Pressure on the CO2 racks in the USA will be simular to those of 410A. I think by the end of the year Food Lion will have 4 CO2 systems running. What's really kool is the Kysor rack and the Hill rack that is being installed right now are both med temp and low temp CO2@ .50 cent a pound!!!

Why not glycol for the med temp? I know the glycol isn't cheap. Install cost?

 

[eng&tech]

Co2 is cheaper than glycol, CO2 has better heat trasfer capacity than glycol.
The flow rates with CO2 are very low so the pipe size get smaller and samaller pump sizes with less energy. Remember the system that Kysor and Hill are putting into Food Lion right now are Low Temperature CO2 using CO2 compressors, the mediuim temp is using CO2 as a secondary fluid and it being moved though the system with a centrifical pump.

Dont get me wrong gylcol is a great system easy to start up and very little maintanace.

 

[jpsmith1cm]

Is there any documentation available for these systems?

I have seen a few of the HP glycol cases, but none of the larger stuff and no CO2 to date.

It is coming, though, and I'd like to be prepared.

Any special tools (gauges or hoses) required?

 

[pherman]

Co2 is cheaper than glycol, CO2 has better heat trasfer capacity than glycol.
The flow rates with CO2 are very low so the pipe size get smaller and samaller pump sizes with less energy. Remember the system that Kysor and Hill are putting into Food Lion right now are Low Temperature CO2 using CO2 compressors, the mediuim temp is using CO2 as a secondary fluid and it being moved though the system with a centrifical pump.

Dont get me wrong gylcol is a great system easy to start up and very little maintanace.

Glycol is a great system and we've been happy with our glycol stores. Interested to see a CO2 store. Wonder about pulldown on the CO2 after a power outage though...

 

[eng&tech]

for documentation on gylcol system go to the technical info section on the Hill website. http:////www.hillphoenix.com/techInfo/handbooks/installIndex.html

I hope that link works.

The only differant tool you'll need for CO2 is a set of 410A gauges, and a CO2 leak detector ( Detec has one)

If you lose power and the system shuts down you have two options. Some store will put in a small generator that will trun on a small condensing unit that will supply just enough refrigeration to keep the CO2 below 400#. But most store's do nothing speacal. If the sytem is off long enough the pressure will rise once the system hits 425# the pressure relief will release CO2. Once CO2 is released it evaporates and cools itself and lowers the pressure and the relief vavle is reset then if the pressure goes back up the vavle opens back up and we repeat until power has been restroed. So if you are off for 10 hours you lose only a small protion of the CO2 (appx 5-8% as test in the lab and in the field). Then once the system power is restored we cool the CO2 and start all over again. remember that CO2 is about 60 cents a pound with a GWP of 1.

 

[thegoodhumorman]

So when are we going to see one out on the west coast- specifically southern California- I think Nor Cal already had one this year start up?
I'm sure I can finagle a job walk!

 

[mspanky]

remember that CO2 is about 60 cents a pound with a GWP of 1.

The CO2 grade required in a Hill plant is close to $30/lb will zero stock in Canada until they bring it in from Europe for us. We will be keeping a 2nd complete charge on site at all times.

 

[eng&tech]

Hill and Kysor and anyone else doing CO2 requires coleman grade CO2. If you are paying
$30/pound your getting ripped off up there in the Great White North. We in the USA pay on average 50 cents a pound US. Not only are we paying about .50/lb it is relativly easy to get. Plus in an emergency Hill has approved industrail grade which is the same stuff used at any McDonalds, Buger King or Wal-mart anyone that use's foutain drinks. At $30/lb even canadan money is alot. To use industrail grade just run it though a sprolan filter-dryer.

 

[eng&tech]

Ive called a couple of my friends in Canada and they tell me you can get it at Air Liquid (I believe that was the name) and the price was ~.60/lb. and was not hard to get. Hill has a CO2 cascade system going in at a store right outside of Toronto should start up sometime early next year. This one has CO2 low temp and CO2 on the mediuim temp. I believe it has 404a on the primary. It just like the system goning in at Food Lion