Slotless BLDC Miniature Pump for Harsh Media: High Power Density through Integrated Thermal and Diffusion Design

Abstract:
This paper presents a miniaturized pump concept designed for continuous operation in chemically aggressive environments. The system is based on a slotless, canned brushless DC (BLDC) motor, which enables direct contact between the motor components and the pumped medium. By eliminating conventional sealing mechanisms, the design reduces mechanical complexity and increases reliability in long-term operation. The slotless stator topology minimizes cogging torque and improves heat dissipation via the pumped fluid, allowing for significantly increased power density in a compact form factor. A key aspect of the design process was the evaluation of material resistance under chemical exposure. To predict longterm degradation behavior, a diffusion analysis was carried out using the Perturbed Chain Statistical Associating Fluid Theory (PC-SAFT). This thermodynamic model allowed for accurate calculation of concentration within the polymer components encapsulation the canned drive as well as the control electronics. This approach enables a targeted selection of chemically resistant encapsulation materials without time-consuming experimental testing. The resulting prototype achieves over 30 W continuous power output in a 20 cm³ motor volume and demonstrates stable operation in harsh media. The integration of diffusion modeling into the development process significantly improved design confidence and material selection. This approach provides a promising path toward robust, high-performance miniature pumps for use in medical, industrial, and autonomous fluidic systems.