Numerical modeling and parametric study of a hollow fiber dialyzer using double porous media approach

Mathematical modeling is one of the efficient methods to improve the design of hemodialyzer and study affecting parameters on dialyzer performance. In this paper, mathematical modeling of hollow fiber dialyzer is done to investigate the effect of various parameters on the clearance of urea and creatinine. The computational domain is considered two-dimensional axisymmetry. The hollow fibers bundle is defined as a double porous media. The Darcy-BrinkmanForchheimer equation is employed to determine flows in porous media. Modified Kedem-Katchalsky equations are used to calculate the transmembrane flow. Continuity, Navier-Stokes and concentration equations are solved by finite element method. The numerical results showed a change in the thickness of hollow fibers from 100 to 25 mu m and a decrease in their inner diameter from 240 to 150 mu m, could improve clearance of urea by 66.7 and 20.7 percent respectively. The increase in blood flow (40 to 120 mL.min-1), dialysate flow (80 to 200 mL.min-1), dialyzer diameter (28 to 38 mm) and length of hollow fibers (15 to 30 cm) increase the clearance of urea by 88.2, 20.4, 35 and 26.2 percent, respectively. The model has been validated and shows good agreement with experimental results. Such studies advance our understanding of the parameters affect the performance of the dialyzer.