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[OLD] Conductive heating


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From: Tom Meuzelaar

Subject: conductive heating


This message is being posted on behalf of Mike Adams, EGI, who is having trouble posting to the list. Message follows below...


I am running a simple conductive heating model. When I run the model and allow precipitation at 20 degrees C, I get a pH of 6.909 and 60 grams of dolomite. When I run it from 20 to 200, I get the same answer at 20 C. If I run it from 20 to any temperature over 200, I get 6.866 and 66 grams of dolomite at 20 C. I am running REACT 5.0.3. The run file is listed below.

Any suggestions as to why this is happening?

# React script, saved Wed Sep 22 2004 by madams

title = "Hay Ranch North for Mixing"

data = "c:program filesgwbgtdatathermo.dat" verify

temperature initial = 20, final = 200

decouple ALL

1.00000751 kg H2O

.00561915555 mol HCO3-

balance on Cl-

.00187730745 mol Cl-

7.89540172e-6 mol F-

.000398024745 mol H+

.00349790126 mol SO4--

.00243512974 mol Ca++

.00154700679 mol Mg++

.000221748772 mol K+

.00591566695 mol Na+

1.61726201e-8 mol B(OH)3

1.44071459e-7 mol Li+

3.02408076e-8 mol HS-

6.23340356e-8 mol CH4(aq)

8.32164143e-5 mol SiO2(aq)

1.11187295e-7 mol Al+++

suppress Dolomite-ord Dolomite-dis

From: Craig Bethke

Subject: Re: conductive heating

When you run a React simulation, the program by default considers only those aqueous species and minerals whose thermodynamic stabilities are known across the range of temperatures considered in your run.

Sounds like your run incorporates one or more species that have stabilities defined in the thermo dataset only from 0-200°C. When you expand the temperature range to 300°C, the species are not loaded.

You can get around this by setting the extrapolate option, but of course this is a little dangerous. It would be better to identify the species in question and finding reasonable stability constants for them at high temperature.

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