Performance Comparison of Alternative Hollow-Fiber Modules for Hemodialysis by Means of a CFD-Based Model.

Nunzio Cancilla,Alessandro Tamburini,Giorgio Micale,Andrea Cipollina,Michele Ciofalo,Luigi Gurreri,Gaspare Marotta

doi:10.3390/membranes12020118

Nunzio Cancilla, Alessandro Tamburini + Show 5 more

Open Access

https://doi.org/10.3390/membranes12020118

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Journal: Membranes	Publication Date: Jan 20, 2022
Citations: 6	License type: CC BY 4.0

Affiliation: University of Palermo, Medtronic (Italy)

Abstract

Commercial hemodialyzers are hollow-fiber cylindrical modules with dimensions and inlet–outlet configurations dictated mostly by practice. However, alternative configurations are possible, and one may ask how they would behave in terms of performance. In principle, it would be possible to depart from the standard counter-flow design, while still keeping high clearance values, thanks to the increase in the shell-side Sherwood number (Sh) due to the cross-flow. To elucidate these aspects, a previously developed computational model was used in which blood and dialysate are treated as flowing through two interpenetrating porous media. Measured Darcy permeabilities and mass transfer coefficients derived from theoretical arguments and CFD simulations conducted at unit-cell scale were used. Blood and dialysate were alternately simulated via an iterative strategy, while appropriate source terms accounted for water and solute exchanges. Several module configurations sharing the same membrane area, but differing in overall geometry and inlet–outlet arrangement, were simulated, including a commercial unit. Although the shell-side Sherwood number increased in almost all the alternative configurations (from 14 to 25 in the best case), none of them outperformed in terms of clearance the commercial one, approaching the latter (257 vs. 255 mL/min) only in the best case. These findings confirmed the effectiveness of the established commercial module design for the currently available membrane properties.

Highlights

Hemodialysis is a membrane-based process in which solute removal occurs mainly via diffusion through the membrane [1]
Two fluids are involved in the hemodialysis process: the blood, rich in undesired solutes, which is purified by a rinsing solution called dialysate, from which it is separated by the membrane
The core of the process is represented by the semi-permeable membrane, which allows the removal of toxic substances and metabolic wastes, such as urea or creatinine, but prohibits the passage of proteins and cells from the blood to the dialysate [4]

Summary

Introduction

Hemodialysis is a membrane-based process in which solute removal occurs mainly via diffusion through the membrane [1]. Two fluids are involved in the hemodialysis process: the blood, rich in undesired solutes, which is purified by a rinsing solution called dialysate, from which it is separated by the membrane. The dialysate is a dilute solution of electrolytes and, sometimes, glucose. This solution contains sodium, magnesium and chloride ions at the same concentration as in normal plasma. The core of the process is represented by the semi-permeable membrane, which allows the removal of toxic substances and metabolic wastes, such as urea or creatinine, but prohibits the passage of proteins and cells from the blood to the dialysate [4]

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Discussion

Conclusion