Computer-aided design of hollow-fiber dialyzers

Abstract

Blood and dialysate flow patterns in hollow-fiber dialyzers are complicated, and hence the flow patterns and mass transfer are difficult to analyze theoretically. Consequently, dialyzers are usually developed by a trial-and-error method. We attempt to design dialyzers by computer simulation analysis in this work. Blood-side and dialysate-side flows were modeled using the Hagen-Poiseuille equation and the Blake-Kozeny equation, respectively. These flow patterns were evaluated as pressure drop and velocity distribution. The mass transfer rate was evaluated as solute clearance. Computed values of the pressure drops and clearance for urea and vitamin B12 were found to agree closely with those obtained experimentally. We evaluated the influences of the inner diameter of hollow fibers, module geometry, and void fraction on the pressure drop and clearance, and computer-aided design was performed.

Incompressible laminar flow through hollow fibers: a general study by means of a two-scale approach

“…In devices for artificial kidney dialysis, [5,6,13], bundles of hollow fibers are sealed into a cylindrical casing. Blood flows in the hollow fibers, while dialyzate flows outside.…”

Development and analysis of an integral fluidodynamic model in hollow fibre for different operational modes

“…2a and b), laminar flow has been considered for the cocurrent and countercurrent operation mode in the lumen circuit, and it has been considered that the same flow rate circulates through each fibre as [18]. The mass balance over a slice dz of the fibres indicates that the flow rate in the lumen circuit is a function of dP F /dz, according to the Hagen-Poiseuille equation:…”

“…Several researchers have used empirical equations to explain the pressure drop in the lumen of the fibres [17] but generally the pressure in the lumen compartment is assumed to drop along the fibre length according to the Hagen-Poiseuille equation [18][19][20]. Greater controversy exits in explaining the pressure profile in the shell.…”

“…Thus, different researchers have considered that the flow in the shell could be simulated by empirical equations as Ergun's equation [19,21,22], although other empirical equations have been used [1]. Other authors [18,23,24] have simulated the flux in the shell by considering laminar flow. Also, Ergun's equation is transformed into the Carman-Kozeny equation, the theoretical pressure drops being a hundred times lower than the experimental data [23].…”

“…On the other hand, different operation modes have been studied by different researchers: continuous open-shell mode [9], closed-shell mode with no recirculation in the shell [9][10][11][12], cocurrent operation [13,51], countercurrent operation [13,18,20] or cross-flow operation. Some studies are theoretical without experimental corroboration and, though these configurations are governed by the same physical principles, the flow and pressure distributions and mass transfer depend on the operation mode.…”