{"id":166834,"date":"2022-02-28T21:03:50","date_gmt":"2022-02-28T21:03:50","guid":{"rendered":"\/forum\/forums\/topic\/how-species-interphase-mass-transfer-is-implemented-in-fluent-hand-calculation-not-matching-fluent\/"},"modified":"2022-04-22T06:24:34","modified_gmt":"2022-04-22T06:24:34","slug":"how-species-interphase-mass-transfer-is-implemented-in-fluent-hand-calculation-not-matching-fluent","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/how-species-interphase-mass-transfer-is-implemented-in-fluent-hand-calculation-not-matching-fluent\/","title":{"rendered":"How species interphase mass transfer is implemented in fluent. Hand calculation not matching fluent"},"content":{"rendered":"
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Hello All,<\/p>\n

Description of problem.<\/strong><\/p>\n

I am trying to simulate the pressurization of ethanol and co2 in a closed vessel. The vessel initially contains liquid ethanol at the bottom and gaseous co2 at the top, separated by an interface. During pressurization, liquid ethanol evaporates from the liquid phase into the gas phase and there is the dissolution of gaseous co2 into liquid co2. Ethanol and co2 are miscible. The fluid flow is assumed to be laminar. The system is isothermal. The fluid properties depend on the composition of the species. Density, viscosity, mass diffusivity changes with mass fraction. <\/p>\n

 <\/p>\n

Modeling Approach.<\/strong><\/p>\n

For now, I am not modeling the entire pressurization process. And I am only considering mass transfer due to dissolution of vapor co2 to liquid co2. I am just modeling a steady-state problem, where my initial conditions are pure liquid ethanol & gas co2. At initial pressure of 6Mpa. <\/p>\n

Transient model, Pressure based solver. Gravity turned off. <\/p>\n

Eulerian multiphase model (Explicit) because the flow is miscible. <\/p>\n

Primary phase: liquid , secondary phase: vapor, surface tension = zero.<\/p>\n

Mass transfer. The mass transfer is driven by the concentration gradient. For now, I used the species mass transfer option. <\/p>\n

Model options: Equilibrium ratio. Equilibrium ratio, constant: 0.4.<\/p>\n

Interphase mass transfer coefficient, overall, 3.3e-7.<\/p>\n

Result.<\/strong><\/p>\n

On the LHS mass fraction of co2 liquid is zero before starting the simulation at t=0. RHS, mass fraction of liquid co2 after running the transient simulation and allowing it to reach a steady state solution. The result make sense. Yes, at steady state the mass fraction show be 0.4 based on how i set it up. <\/p>\n

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