Heat transfer, cooling channels and PEM fuel cells

Scientists have conducted research to better understand the cooling of polymer electrolyte membrane (PEM) fuel cells and the relationship to temperature gradients across the membrane.

The study is the work of a research group from the Department of Energy Engineering at the University of Seville in Spain and collaborators from AICIA in Spain and the Harbin Institute of Technology in China.

The research was based on the numerical analysis of heat transfer for coil-type cooling channels in a PEM fuel cell, evaluating the influence of operating conditions to establish a new correlation for heat transfer performance, i.e. the Nusselt number. The results determined that the coolant mass flow and the bipolar plate thermal conductivity had a greater effect on the cooling capacity of a PEMFC stack.

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

The research team, which included Laura González-Morán from AICIA and Christian Suárez from the University of Seville, studied the cooling capacity of the PEM stack.

The analysis was performed using Computational Fluid Dynamics (CFD) simulations in a 100 square centimeter active area cell with coil-type cooling channels, varying the coolant type, mass flow rate, contact thermal resistance, bipolar plate material, and cooling channel design. A new heat transfer correlation was proposed with validity for a wide range of operating conditions.

Temperature distribution across the membrane for low, medium and high refrigerant mass flow in the case of two different cooling channel designs. (Image: University of Seville)

The main result of this research (a new correlation for the Nusselt number for PEM fuel cell stacks that can be used for a wide range of operating conditions) will facilitate the design of the cooling system in a PEM stack, thus contributing to the design of stacks with higher durability and performance.

The study is titled “A numerical study on heat transfer for serpentine-type cooling channels in a PEM fuel cell stack”. It has been published in the academic journal Energy. (Source: University of Seville)