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Thermo database compatibility


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A hard drive crash corrupted my modified thermo dataset for version 8 and I cannot figure out why it cannot be read by GWB programs. Newer version of the same dataset have be recreated using V. 10 and are not compatible with version 8. How can I get the V. 9/10 datasets to be read by my V. 8?

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Hi,

 

If you only have access to GWB8 (no TEdit app) then you'll need to modify the dataset in a text editor like Notepad. It would be best to use one of the datasets installed with GWB8 (compiled at the same principal temperatures) as a guide. The changes you'll need to make include:

 

  1. If the dataset has a .tdat extension, you'll need to change it to .dat.
  2. You'll need to change the dataset format (second line of the dataset) from oct13 to oct94.
  3. You'll need to add four reactions (log k for Eh reaction, O2 gas solubility, h2 gas solubility, n2 gas solubility) to the tables section of the thermo dataset (so after the c h2o 4 table). It's probably easiest to copy these from one of the datasets that come installed with GWB8
  4. You'll need to delete the Free electron reaction, which is located between the aqueous species and the minerals. This reaction, in modified form, appears in the log k for Eh reaction.
  5. If you changed the redox pivot [H2(aq) instead of O2(aq)] or the species used to balance redox coupling reactions [O2(g), e-, H2(aq), H2(g) instead of O2(aq)] then you'll need to rebalance those reactions and recalculate the log Ks. The Rxn app will be useful. If all of your redox coupling reactions are written in terms of O2(aq), as was required for GWB8, then there's nothing else to do.

For more information, Appendix A.1.5 in the GWB Reference Manual describes redox pivoting and redox coupling reactions in the new format thermo datasets (Releases 10 and 11). And Appendix A.1.12 describes the differences between the current (oct13) and older(oct94) formats.

 

If you have access to TEdit (you're running Release 10 or 11), then, as long as O2(aq) is still the redox pivot and redox coupling reactions are written in terms of O2(aq), you can simply go to the Header section of the dataset and change the dataset format to oct94, then click Apply, then save as a .dat file. The program will take care of the four reaction tables and the free electron reaction.

 

BTW, I moved your post from the archive of older topics to the front page of the GWB forum. Please be sure to post on the front page in the future so that your posts are more visible.

 

Hope this helps,

 

Brian Farrell

Aqueous Solutions LLC

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