Hi, I am a new user of TOUGHREACT. I am using ECO2N to simulate diopside dissolution and carbonate mineralization in a temperature range of 6.4˚C - 18.9˚C and a pressure range of 0.1 - 5.1 MPa. I have input constant pCO2 values (bars) that would reflect the maximum solubility of CO2 in water for each P and T condition. In the chemical.inp I have pCO2 values with IGASFIX=1 and in flow.inp I have the corresponding mass fraction of CO2 specified. For the lower T-P range (6.4 -16.4˚C and 0.1 - 4.1 MPa), my estimates of max pCO2 for CO2 solubility match with that calculated by TOUGHREACT, but beyond that, TOUGHREACT calculated higher pCO2 values. Can anyone tell me what equations and steps TOUGHREACT is using to calculate the pCO2 values from the mass fraction of CO2 input in flow.inp? Any help would be very helpful. Below are my P-T conditions. Thanks.
Temp (˚C)
P_depth (Mpa)
6.4
0.101325
7.65
0.601325
8.9
1.101325
10.15
1.601325
11.4
2.101325
12.65
2.601325
13.9
3.101325
15.15
3.601325
16.4
4.101325
17.65
4.601325
18.9
5.101325
2replies
TOUGHREACT Developer
Eric_Sonnenthal
1 mth ago
Reported - view
Hi Piyali,
Did you set a salinity in the INCON? Also, which thermodynamic database are you using? If you send your input files, it will be easier to see why it is higher than you expect. What are you comparing it to?
regards,
Eric
Piyali_Chanda
1 mth ago
Reported - view
Hi Eric,
Thanks for responding to my queries. I am currently running the model assuming pure water (i.e., salinity = 0). So there is nothing in the INCON and GENER. I am only chemical.inp, flow.inp, and solute.inp to specify the run conditions. I have calculated how much maximum CO2 can be dissolved in each P & T condition and estimated the mole fraction of dissolved CO2. Then, I tried to calculate the fugacity of CO2 (pCO2) that I would need to achieve the maximum mole fraction of dissolved CO2 estimated for each P & T. Based on my estimation, I inserted the pCO2 values in the chemical.inp file and the mass fraction of CO2 in the flow.inp file for each P-T simulation. My estimation of pCO2 (col #6) matches well with TOUGHREACT calculated CO2(g) (col #7) in kdd_tim.tec file after each simulation for the lower P-T range (6.4 -16.4˚C and 0.1 -4.1 MPa). But at higher P-T conditions there is a significant difference between my pCO2 estimation and TOUGHREACT calculated CO2(g). So, I am trying to find what formulations/equations TOUGHREACT is using to calculate the CO2(g) values in kdd_tim.tec from the input value of the mass fraction of CO2. Following are my run conditions and contents of my chemical.inp, flow.inp, and solute.inp files. I would appreciate it if you could point me to the geochemical equations TOUGHREACT is using to calculate the CO2(g) value from the input CO2 mass fraction.