co2 transcritical cycle: through the critical point

[couf2703]

Hi there,

I'm wondering: what physically happens when you got a CO2 transcritical cycle going but for one reason or another the high pressure side would drop until it crosses the critical pressure. What happens ? A smooth transition to a subcritical cycle ?
(My EES model cannot go through the critical point )

Thank you

Fred

 

[davefitz]

nothing special- no space-time continuum wormholes that result in time travel to the future. It behaves just like a supercritical steam cycle, used on a couple of hundred large electric power plants.

If your process soemhow includes long residence time at the critical point and there are any impurities in the CO2, then one can expect unusual solubilities and crystalization processes would occur. There is a whole industry that is based on such unusual processes.

 

[dcasto]

actually, going through a criticle point is not an issue, but remember that the criticle point is a bell curve of sorts. the molecules do not just go pop, all gas or all liquid. you will have a mixture of gas and liquid for an area around the point. That area? With ethylene we try to stay 10 degrees F away from the point of 50 psig to assure you don't have two phases.

 

[couf2703]

Thanks a lot guys. I get it!