UNIQUAC Interaction Parameters
Simulate chemical processes using advanced thermodynamic models
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I built two compounds using MODFAC-Nist and Joback groups, and I hand calculated their UNIQUAC R and Q parameters. I'm trying to estimate the UNIQUAC interaction parameters between several compounds, including my built ones, in the Configure Property Package window. However, when I estimate the interaction parameters using the "Estimate MODFACT Nist" function, all interaction parameters involving my built compounds return a 0 value while compounds already in the DWSIM database have non-zero interaction parameters. I applied Joback calculations where possible, so I'm not quite sure what I may be missing in my compound files. The only thing I can think of is that my compounds return a 0 for critical volume, and all the other compounds that had non-zero estimated interaction parameters had non-zero critical volume values. Thank you for your help
I found experimental VLE data that I can input for doing a Txy data regression for estimating the interaction parameters between furfuryl alcohol and furfural. When I tried using MODFACT-NIST to give an initial estimation, I get the following error "Could not find interaction parameter for groups CH3OH/AC2O. My confusion is that I didn't use either of those MODFAC groups to build my furfuryl alcohol compound. I wonder if this is why I couldn't get an initial estimation for the parameters on the Configure Property Package page. If you can help me out, I appreciate it. Here is a picture of the error and then my compound file. You guys tried modifying my previous files but the Joback and MODFAC-NIST groups weren't exactly correct in those files. The one I attached here contains the best approximation for the MODFACT-NIST and Joback groups. Thank you for your help.
in this case the problem is with DWSIM, not your compound. Not all NIST-MODFAC interaction parameters are available for free and this specific one also isn't.
For modeling purposes using the free software, would you suggest just ignoring the missing interaction parameters?
if you have experimental data, you can regress parameters for either NRTL or UNIQUAC.
Last edit: Daniel Medeiros 2023-01-24
Hi Daniel,
Thank you for your quick help. I tried regressing my experimental data using UNIQUAC. I attached the paper I got the VLE data from, for furfuryl alcohol and furfural. But I get a regression error that I don't understand. Could you take a look at this file and see what's generating the error? Thank you for all your help