A research group at the Department of Energy Engineering of the University of Seville and collaborators at AICIA and Harbin Institute of Technology in China have carried out an investigation for the better understanding of the cooling of Polymer Electrolyte Membrane (PEM) fuel cell stacks, and the relationship with the temperature gradients in the membrane. The investigation was based on the numerical analysis of the heat transfer for serpentine-type cooling channels in a PEM fuel cell, assessing the influence of the operating conditions to establish a novel correlation for the heat transfer performance i.e. Nusselt number. Results determined that the coolant mass flow and the bipolar plate thermal conductivity presented a higher effect on the refrigeration capability of a PEMFC stack.

Refrigeration of the stacks play an important role in the design of PEMFC stacks because proper cooling helps to mitigate the risks caused by excessive temperature gradient that led to degradation and detrimental effects on the integrity of the membrane. Consequently, refrigeration of the stacks plays a key role in the efficiency and durability of a PEM stack.

The refrigeration capability of the PEM stack was studied through Computational Fluid Dynamics (CFD) simulations in a 100 cm² active area cell with serpentine type cooling channels, varying the coolant type, the mass flow rate, the thermal contact resistance, the bipolar plate material and the design of the cooling channels. A novel heat transfer correlation was proposed with validity for a comprehensive range of operating conditions.

The main result of this research (a novel correlation for the Nusselt number for PEM fuel cell stacks that can be used for a wide range of operating conditions) will facilitate the cooling system design in a PEM stack, foreseeing whether designs would eventually lead to degradation and thus contributing to the design of stacks with longer durability and performance.