Why does the partial pressure of carbon dioxide change so much when SG is greater than zero？
I use eos2 to simulate phase transition (phase change)
it is a very simple model to study the Pco2 change.
but it is a little bit hard to explain.
I found SG>0, the PCO2 will change dramatically and weird.
can anyone help me to explain this phenomenon?
Very interesting problem, and nice illustrations. I have no experience with EOS2, but I think what is happening is that for the T=99 case when you have single-phase liquid conditions for all times, Pco2 is telling you the amount of CO2 that is dissolved in the liquid phase, via Henry's Law. In Cell 2, Pco2 gradually increases as the P difference between cells 1 and 3 drives flow with more dissolved CO2 into cell 2. There is no gas phase because the combined partial pressures of water vapor (Psat) and CO2 (Pco2) is less than the total pressure. For the T=100 case, Psat is higher so a gas phase forms, but in cell 2 when T<100, there is not that much water vapor, more of the gas phase is CO2, and thus Pco2 is bigger. As T increases to 100, Psat increases and Pco2 decreases. Could you post your input file? I'd like to try a few things with it, and maybe compare EOS2 to ECO2N, which I have used a lot. Christine