Nonequilibrium Mass Transfer Sample Clauses

Nonequilibrium Mass Transfer k1 For nonequilibrium mass transfer, a linear driving force rate, as proposed by Xxxxxx et al. [1992] is used. The mass transfer rate between NAPL and water interface for each NAPL component is a mass transfer coefficient times the driving force that is the difference between the equilibrium and phase concentrations. The mass transfer coefficient is currently modeled as a constant. The computational procedure for non- equilibrium mass transfer requires the calculation of the equilibrium organic concentrations, Coeq, first. Then we solve for the phase concentrations and saturations for the nonequilibrium case. It is similar to the equilibrium case, except that the mass balance equation for the organic in the water phase is used instead of constant partition coefficient of the equilibrium case. The organic species mass balance equations in the water phase are given by:  nc  ∂φ1 − ∑ Cˆ n [ 1 + ca (P1 − PRa )]S1C o + ∇ ⋅ 1 + ck (P1 − PRa )]  n=1  k k1 ¸ [ a ¸ o ¸ ¸ o ∂t k1 k1 k k1 k1 = Ro + Qo + Mo (Coeq − Co ) k = 1, 2, 3, ...,no (Ck1u1D k1 ) (7.4)

Nonequilibrium Mass Transfer. Once the equilibrium saturations and concentrations are known, the organic species mass balance equations in the aqueous phase (Eq. 7.12) are used to calculate the nonequilibrium saturations and concentrations. A single mass transfer coefficient is assumed for all organic components.  nc  ∂φ1 − ∑ Cˆ n [ 1 + ca (P1 − PRa )]S1C o  n=1  k k1 ¸ [ a ¸ ∂t + ∇ ⋅ 1 + ck (P1 − PRa )](Co ¸u1D¸ o ) (7.12) k1 k1 = Ro + Qo + M (Coeq − Co ) k = 1, 2,3,..., no k1 k1 k1 k1 where the equilibrium concentrations and saturations are already known from the phase behavior calculations.