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Table 1 Summary of model approaches used in the present work

From: Validation of hydrogeochemical databases for problems in deep geothermal energy

Code

PHREEQC

ChemApp

Parameter file

phreeqc.dat

llnl.dat

pitzer.dat

slop16.dat

Source of thermodynamic data

Unknown

Mainly: slop

Unknown

slop16

Activity model

Extended Debye–Hückel equation

Pitzer equations

Davies equation

Approx. ionic strength limits of the activity model \(\left( {\mathrm {mol}}/{\hbox {kg}}\right)\)

0.1–3a

0.1–3a

6a

0.1–0.5a

Pressure dependence

HKFmoRR

None

HKFmoRR

HKF

Temperature dependence

Fitted polynomial equation or two-term extrapolation [cf. Eqs. (1) and (2)]

HKF

  1. aDepending on system composition