Constructal design of multi-inlet flat plate cooling systems: Experimental analysis and numerical simulations

Proton exchange membrane fuel cells (PEMFCs) require effective thermal management to ensure both low operating temperatures and high temperature uniformity, which are critical for performance and durability. In this work, a novel flat plate cooling channel designed based on the Constructal law was developed and assessed. The proposed design consists of a multi-inlet architecture with two inlet trunks merging into a single outlet along the central axis of the plate. A parametric numerical study was conducted by varying the bend radius and the distance between the inlet channels and the plate edges. The numerical model was validated against experiments performed on selected aluminum 3D-printed plates, showing average deviations below 1.0 °C in maximum temperature and 0.5 °C in mean temperature. The validated model was then used to identify the optimum configuration, defined as the best compromise between low maximum and mean plate temperatures and high temperature uniformity. The effects of pumping power and thermal input on this optimum design were further analyzed numerically and experimentally, showing excellent agreement between both approaches. Finally, the optimum multi-inlet configuration was compared with reverse-flow multi-outlet, single-channel, and canopy-to-canopy cooling plates also designed based on Constructal approaches, all evaluated under the same pumping power constraint. The results show that the optimum multi-inlet design yields the lowest maximum temperature and the best temperature uniformity. This improved thermal performance is mainly attributed to its lower pressure drop, which enables higher coolant mass flow rates under the same pumping power.