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Title: FREZCHEM : a chemical-thermodynamic model for aqueous solutions at subzero temperatures
Authors: Strategic Environmental Research and Development Program (U.S.)
Marion, Giles M. (Giles Michael)
Grant, Steven A.
Keywords: Aqueous solutions
Electrolyte solutions
Computer modeling
Computer models
Computer simulation
Publisher: Cold Regions Research and Engineering Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Special report (Cold Regions Research and Engineering Laboratory (U.S.)) ; 94-18.
Description: Special Report
Abstract: This report documents a FORTRAN version of the Spencer-Mailer-Weare chemical thermodynamic model for aqueous electrolyte solutions at subzero temperatures (FREZCHEM). FREZCHEM is structured to predict the chemical composition and unfrozen water of aqueous solutions between -60 °C and +25°C at atmospheric pressure (0.101325 MPa). FREZCHEM includes two reaction pathways: 1) freezing at variable temperature and fixed total water and 2) evaporation at variable water and fixed temperature. Activity coefficients and the activity of water are calculated using the Pitzer equations, which are valid to high solution ionic strengths (≈ 20 mol kg^-1). Fifteen chloride and sulfate salts of sodium, potassium, calcium, and magnesium are included in the model. Predicted and experimental measurements of solute molalities and the unfrozen water fraction during seawater freezing are in good agreement. At -50°C, 0.3% of seawater remains unfrozen with 99.7% of Na and 95.5% of Cl having precipitated into one of four salts. FREZCHEM should find many applications in physicochemical studies of aqueous solutions and freezing.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Special Report

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