co2 control strategy

[COO2]

:confused: Hi,
There are following questions about the CO2 Booster system control.Thanks for some information about the CO2 transcritical system control.

1. AS for the transcritical system, how to determine the optermal outlet pressure of gas cooler, which has close relation with the COP?
2. How to design the capacity control of compressors. can the suction pressure decide the on-off of compressors? how to control the on-off of MT and LT compressors?
3. how to control the opening of electrical expension valve for the evaporation?

Best Regards

[NoNickName]

I think you are confusing a transcritical cycle with a two stage subcritical booster cycle. If you are really looking for a transcritical double stage, then have a look here http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V4R-4HGM7BK-2&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=4e2b77b375d948ab8b25b0fbbb71d811

[COO2]

Thanks
yes, i am looking for the optimal control method of transcritical double stage cycle. the first expansion valve after the gas cooler reduces the pressure from 110bar to 40bar. after expansion, the CO2 is the mixture of liquid and gas. this point(40bar) has close relation with the system performance. normally, this valve use the PID controller. so how to determine the PID constants to ensure the high system performance and steady pressure conditions are what i want to discuss.
by the way,where can i download this paper?