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guapo
30-03-2006, 08:19 AM
Hi all,
Any body has Idea for the load calculation for the CO2 reefer unit? reefer unit should start @ 300 psi co2 press & stop @ 200 psi co2 press.

Volume=75 tons

Suction ?
Discharge 45C
Refrigerant R404a

Thanks,
eric

Andy
31-03-2006, 10:07 PM
Hi Guapo:)

In short no but I have worked on them and selected units in the past. Experience and trial and error are the norm. I have seen some very poor matches between the coil in the tank and the conensing unit. Best check out a few similar installation in your area. Insulation on the tank would be important, North or South facing would be important as well as the surface area of the tank (facing south).
Usage of CO2 is also important, if the tank has a large volume of CO2 drawn off every day it may not even need cooling.

From Memory a tank this size would have a 10hp unit on it.

Hope this helps.

Kind Regards. Andy:)

US Iceman
31-03-2006, 11:54 PM
You first have to know the heat load onto the CO2 storage vessel. As Andy stated the sun exposure is one important aspect of this. Another is the actual temperature difference across the vessel & insulation.

The sun exposure and the temperature difference comprise the total TD across the vessel. When the heat enters the CO2, the CO2 flashes off. This causes the rise in pressure. By condensing the vapor, the pressure is maintained in the vessel.

The actual liquid level in the vessel is the surface area exposed to the heat. This is where the flash gas comes from. The heat that enters the vapor space is negligible.

As Andy said, you can either match up the condensing unit capacity when compared to an equivalent vessel size, or, you need to know the vessel construction and insulation and liquid level.

Essentially, the cooling load of the condensing unit is equal to the boiling rate of the CO2 in the vessel.

The equivalent cut-in pressure of the condensing unit should be such that the CO2 pressure is well below the relief valve setting of the CO2 tank. Is your CO2 tank rated for a pressure higher than 300 psig?

chemi-cool
01-04-2006, 08:45 AM
Hi guapo,

I maintain these units for years.
Tomco ones,
The suction is between 20 to 25 psi, depending on ambient temp.

We stop the refrigeration unit at 260 psi.

Chemi:)

guapo
01-04-2006, 02:33 PM
Thank you guys for the reply,

The insulation of the co2 is polyeurethane(6" thik). The tank is oval shape and totaly exposed to sun light. The tank working pressure is 400 psig.

regards
Guapo

Prashant Kumar
09-03-2009, 01:04 PM
Hi guys.am new to this industry.and am being give na task of computing the required referigeration load for a Vertical Co2 polyeurethane(6" thik) insulated tank.The problem is when continoulsy running the chiller for 8-9 hrs, the pressure drop is negligeble..ie when the Chiller was switched on, the pressure was 21bar and after continously running for 9 hrs the pressure inside the tank was 20.5 bar..
Should it be considered that the chiller used is inssufficient.
It would be great if you could give me a few inputs..Following are the tank details:
Tank capacity: 10000T
6"thk polyeurethane insulated vertical tank.
Ref: R404A

Prashant Kumar
10-03-2009, 10:40 AM
sorry a small correction..the capacity is 10T...regret the mistake

p_p
10-03-2009, 12:46 PM
I think its probably sorted now, the thread is 3 years old:eek:



PP