Lumped parameter modeling and experimental characterization of pressure effects in a roller-type peristaltic pump with neoprene tubing for dialysis machines.

Abstract

Dialysis machines are vital devices for individuals with chronic kidney diseases, functioning as artificial kidneys to purify blood by removing waste and excess fluid. At the core of these machines are volumetric pumps, with peristaltic pumps being particularly essential for their high precision and gentle handling of sterile fluids such as blood.

This study focuses on the experimental characterization of a four-roller peristaltic pump with a neoprene tube, analyzing its volumetric efficiency under varying suction (Pin) and discharge (Pout) pressures, motor speeds (rpm), and at a constant temperature (35 °C). A lumped-parameter model was subsequently developed to replicate the pump's real behavior using Siemens’ Amesim software.

The pump was modeled with four isolated pumping volumes, assuming complete occlusion of the tube by the rollers. The deformability of the neoprene tube was incorporated using a generalized tubing law, treating it as a linearly elastic material.

Experimental results showed that due to neoprene's high deformability, the pump's flow rate depended significantly on Pin. Variations in suction pressure altered the tube's expansion and contraction, affecting the volume of liquid between rollers. Conversely, the flow rate showed minimal dependence on Pout. These trends were also validated through the lumped-parameter model, with simulated data aligning within the experimental volumetric efficiency's mean ± one standard deviation for all tested conditions.

This study provides a simplified but accurate and validated model for peristaltic pumps, which provides the total flow processed by the pump, the flow and pressure ripples and the pressure trend within the pumping volume.