Experimental study of the thermal performance of chaotic geometries for their use in PEM fuel cells

• We proposed a new type of geometry, based on chaotic advection in laminar regime, for the coolant channels PEM fuel cell stack.
• The thermal performance of the chaotic geometries (V- and C-shaped) is compared to a straight tube configuration performance.
• The internal heat transfer coefficient is increased for the chaotic geometries compared to the straight tube.

In order to improve the thermal performance of heat exchangers used in the bipolar plates of PEM fuel cells, we suggest replacing the networks of straight channels by geometries generating chaotic flows. In transport applications, high heat densities are generated because of the combined high heat fluxes and the imposed compactness of heat exchangers. Moreover, the convective regime in the cooling channels is laminar and the channel network has to be as thin as possible to limit the electrical resistance through the bipolar plates. In such extreme conditions, the generation of spatial chaos by geometrical perturbation in the heat exchanger is a relevant way to intensify heat transfer. In this paper, an experimental study is presented for two chaotic advection geometries and a straight tube. A specialized test bench was designed and built. The channels were placed in a counterflow heat exchanger with a laminar flow in the center and a turbulent flow in the annulus. Heat exchange was carefully analyzed to obtain the convective heat transfer coefficient for each channel.