Mass transfer of urea, creatinine and vitamin B-12 in a microchannel based membrane separation unit

Micro energy and chemical systems (MECS) are microfluidic systems where energy and chemical processes can be intensified by decreasing the characteristic length. This project focused on bulk fluid processing using MECS technology to intensify the mass transport of a dialyzer. The objective of this project was to design a model from first principals that could function as a design tool for a microchannel based membrane separation unit. The device was composed of two parallel arrays of microchannels separated by a 20 [mu]m membrane. Experimental data was collected for three separate microchannel devices and three solutes: urea, creatinine, and vitamin B-12. The channel depth and width for the two primary devices tested were 100 [mu]m and 200 [mu]m respectively. Multiple parameters were tested these included the fluid velocity in the channels, an imposed a pressure offset, and a reduced flow rate on one side of the membrane. A 3-D model was derived using the Naiver-Stokes equations for transport in the channels and Darcy's law for transport across the membrane. The scaler transport of the solutes was modeled using the convection diffusion equation and was decoupled from the momentum transport since all concentrations were assumed dilute. The semi-implicit method for pressure-linked equations (SIMPLE) was used to couple momentum and pressure equations. The model was solved using MATLAB. The model results were in good agreement with the experimental data and had a maximum difference of about 10%.