Membrane separation

This page outlines the basic model implemented in the MembraneSeparator unit. The unit is intended for simple simulations of gas separation membranes or pervaporation modules used in purification and CO2 capture.

Flux model

For each component $i$ a constant permeate fraction $f_i$ can be specified. The molar amount transferred to the permeate side is \(N_i^{\text{perm}} = f_i N_i^{\text{feed}}\) where $N_i^{\text{feed}}$ is the molar amount in the feed stream. Components without a specified fraction use a global default value.

A more rigorous model could employ Fick’s law of diffusion through the membrane \(J_i = P_i \left(p_{i,\text{feed}} - p_{i,\text{perm}}\right)\) where $P_i$ is the permeability of component $i$ and $p_i$ are partial pressures. The separator can now perform this calculation mode when permeabilities and a membrane area are supplied.

Usage

MembraneSeparator mem = new MembraneSeparator("mem", feedStream);
mem.setDefaultPermeateFraction(0.1); // 10 % of each component permeates
mem.setPermeateFraction("CO2", 0.5); // override CO2 fraction

// Alternative using permeability coefficients mem.clearPermeateFractions(); mem.setMembraneArea(5.0); // m^2 mem.setPermeability(“CO2”, 5e-6); // mol/(m2sPa) mem.setPermeability(“methane”, 1e-6); ``` After running the process, the permeate and retentate streams can be obtained via getPermeateStream() and getRetentateStream().