Co2 System Design

[Brad Chen]

Now, i try to design a CO2 system for experiment study. But, i am not sure how to decide the volume of a tank used to hold the gas at standstill. How and where do this tank set?
if leakage happen, what kind of sensor can be used to detect it.
Can you give me an example?
Thanks very much for your help!

[Andy]

Brad,
simply the vapour volume off a PH diagram or a chart value from volume tables for R744 at room temperature.

You could also use a condensing unit and a cooling coil operating on a high pressure cut in switch, to maintain the pressure.

Kind Regards. Andy

[US Iceman]

HI Brad,

The volume of the tank you are describing is based on the change in volume of the total CO2 charge. During operation the pressure will be low. At standstill, the CO2 will evaporate (unless a separate refrigeration system maintains the temperature as Andy described).

When the CO2 gas volume increases the total system volume is occupied with CO2.

If you take the total mass of CO2 and calculate the volume of gas that will be formed (at the standstill condition, which is based on the ambient temperature and the design pressure of the system).

The total volume of the CO2 system is deducted from the total volume of the CO2 at the standstill condition. The difference in volume is that required by the tank (usually called an expansion tank or fadeout drum).

You can check this by using the gas laws. PVT1 = PVT2.

For leaks you can use a CO2 detector. A level detector may not work since the refrigerant will vaporize during shutdown and the liquid level disappears.

PS. Welcome to RE.

[Dan]

If you can't fix it leave it that no one else will

LOL, Andy!

Brad, I am curious. I am assuming that you are experimenting with a subcritical application such as cascade refrigeration or using the CO2 as a secondary refrigerant. What sort of system are you experimenting with? And welcome to RE forums.

[Peter_1]

I was thinking the same way Dan, welcome Brad.
May I ask, what company you're working for?

[Brad Chen]

Hi,
I am still a postgraduate student in Jiaotong University. My teacher ask me to deal with a cascade CO2 system. I think, CO2 as a refrigeration actually have no big difference with other refrigerants If you could treat pressure and heat exchanger very well, all things would be OK.
I am now in the process of design, if in trouble, your valuable suggestions are actually very helpful to me.
Thanks.