Improving cooling efficiency of rectangular li-ion batteries using hybrid-nanofluid-based mini-channel cold plates

This research experimentally and analytically investigated the thermo-hydraulic and thermodynamic performance of three mini-channel cold plate (MCCP) geometries—straight (MCCP#1), single serpentine (MCCP#2), and triple-parallel serpentine (MCCP#3)—using Al 2 O 3 –SiO 2 (70:30) hybrid nanofluid (HNF) dispersed in an ethylene glycol–water mixture (EG50:W50). for battery thermal management systems (BTMS). The HNF exhibited enhanced thermophysical properties with improved thermal conductivity and moderate viscosity increase at 1.0% concentration. Heat transfer performance followed power-law correlations, with the Nusselt number expressed as Nu = 0.4439 Re a Pr b , demonstrating significant enhancement in convective heat transfer coefficient over the base fluid. Pressure drop increased quadratically with Reynolds number, maintaining acceptable hydraulic penalties. MCCP#3 demonstrated superior performance with uniform flow distribution, minimal temperature gradient (ΔT < 4°C), and Performance Evaluation Criterion (PEC) of 1.43–1.70. Entropy generation analysis confirmed thermal irreversibility dominance ( Be < 0.1), contributing over 90% of total entropy, while maintaining high exergy efficiency (Ψ = 0.83–0.91). Flow visualization revealed curvature-induced secondary vortices in serpentine channels that enhanced mixing and boundary-layer disruption. The integration of Al 2 O 3 –SiO 2 HNF with MCCP#3 provides an energy-efficient, thermodynamically optimized cooling strategy for next-generation electric vehicle BTMS applications.