Influência de parâmetros geométricos e operacionais no processo de hemodiálise via CFD.

Abstract

The incidence of renal insufficiency has gradually increased over the years, affecting a significant portion of the world population. In Brazil, approximately 130,000 people are undergoing dialysis due to this disease, being normally submitted to three weekly dialysis sessions with an average duration of four hours, an indispensable practice for patients with chronic renal failure. In view of the above, several researches have been developed both in the experimental field, as well as in analytical and numerical ways, aiming to understand and improve the artificial kidney (hemodialysis). In this sense, the present work aims to numerically study the hemodialysis process in a hollowfiber dialyzer, contributing to the understanding of the dynamics inside the equipment, as well as to evaluate the influence of operational parameters on the efficiency of toxin removal via Computational Fluid Dynamics (CFD), using Ansys® Fluent software. A mathematical model was developed and validated by comparison with experimental and numerical data available in the literature; the mesh quality was evaluated using the Mesh Convergence Index (ICM) method, an analysis of the hollow fiber membrane was carried out for different contaminants; the feed flow was investigated together with the tangential and pulsed feeds. The results in the form of pressure, velocity and volumetric fraction fields, streamlines, velocity vectors, and clearance are presented and analyzed. The numerical results show that the mathematical model used is capable of expressing the fluid behavior inside the hollowfiber membrane, presenting a greater toxins removal for high inlet fluxes. Furthermore, it was verified that the tangential feeding has little influence on the process. On the other hand, the pulsed inlet had a clearance greater than the axial inlet for the frequency of 30 rad/s, with an increase in clearance being observed with the increase in frequency and a decrease in the amplitude of inletting the lumen.