Carbon Dioxide gas compression 2

[burtb]

Hello

I am working on a project which is using Carbon Dioxide as a refrigerant bath, which must then be recovered. In order to calculate compressor load requirements, I am needing to know at what point, temperature and pressure, the gas would possibly cross the phase boundary as it is compressed from 4 atmosphere and 215 degrees K to 58 atmosphere? Also, what would the temperature be when it reaches 58 atmosphere pressure? Can anyone help with these calculations?

Thanks in advance for any help

 

[MortenA]

You can find a lot of reference material re. co2 here:

http://www.union.dk/media/CO2-GB.pdf

best regards

Morten

 

[burtb]

Thank you Morten, will try.

 

[brian999]

Try

http://webbook.nist.gov/chemistry/

 

[dcasto]

good luck find a compressor that do the job in a single stage. I say that because your question about dischare temperature depends on how many stages you are going through and your intercooler temperatures.

NOW, you can use the links and think about multiple stages...

 

[Montemayor]

Burtb:

By “I am working on a project”, I have to guess that you have a school assignment or project involving this topic. I don’t have a problem with helping you, but you will have to do the work:

1. Get ahold of a Mollier Diagram for CO2. Mortena has posted the source of a good, free and down-loadable diagram on these Forums and you should be able to find it by using the SEARCH database.

2. You reinforce my suspicion that you’re a student because you use an ambiguous pressure term, without stating if it is absolute or gage. I’ll assume it is absolute and the overall compression ratio you are working with is 58/4 = 14.5 – far too high to accomplish in one stage. You will need a 2 – or better yet, a 3 – stage compressor if you are dealing with a reciprocating type. You don’t even state the type of compressor you’re writing about.

3. By determining the number of compression stages, you have a start on determining the discharge temperature of each stage. Get ahold of a good Thermodynamics book (unless you already have one) and use the reversible adiabatic (isentropic) equation for determining the discharge temperature.

4. I hope you already know that in order to liquefy the CO2 at 58 atm. (852.4 psi) you have to cool it to at least 70 oF (21 oC). This is the high pressure liquid CO2 that you would subsequently expand to obtain a lower pressure and lower temperature liquid CO2 for your refrigeration purposes.

 

[burtb]

Thank you Montemayor and others.

My work is mechanical and I was asked to check out an aspect of the project that was more involved than I had anticipated and am comfortable with. Your comments have enabled me to pass that part off and stop banging my head against a wall.

Thanks again