Mass fluxes and partial pressures of NH3 and H2O vapour

[djb14128]

Hi,

I'm just wondering if there is a way for me to calculate the partial pressures and fluxes of NH3-N and H2O (water) vapour using IPHREEQC.

Kind regards,
djb14128

[dlparkhurst]

The partial pressures of NH3(g) and H2O(g) will appear in the "Saturation  indices" section of the output. For a gas, SI = log10(fugacity). Fugacity = pressure * phi / 1 atm.  For ideal gases, phi = 1. At low pressures fugacity will essentially equal pressure, even in Peng-Robinson calculations.


Not sure what you are looking for with the fluxes. PHREEQC will calculate mole transfers of NH3 if you specify a partial pressure with EQUILIBRIUM_PHASES, or if you react a solution with a GAS_PHASE. You usually cannot specify a partial pressure of H2O(g) because it is fixed at a given temperature; you can define H2O(g) as a component in a GAS_PHASE.

[djb14128]

The partial pressures of NH3(g) and H2O(g) will appear in the "Saturation  indices" section of the output. For a gas, SI = log10(fugacity). Fugacity = pressure * phi / 1 atm.  For ideal gases, phi = 1. At low pressures fugacity will essentially equal pressure, even in Peng-Robinson calculations.


Not sure what you are looking for with the fluxes. PHREEQC will calculate mole transfers of NH3 if you specify a partial pressure with EQUILIBRIUM_PHASES, or if you react a solution with a GAS_PHASE. You usually cannot specify a partial pressure of H2O(g) because it is fixed at a given temperature; you can define H2O(g) as a component in a GAS_PHASE.

Thanks.