Masoud Haghshenasfard

A novel design of a combination of the serpentine and parallel flow fields configuration is suggested to increase the performance of the proton exchange membrane (PEM) fuel cells by improving pressure drop, oxygen transport, and water removal. A three-dimensional model of PEM fuel cell is numerically investigated for conventional and novel flow fields (called V-Ribbed). The results showed that in the V-Ribbed design, not only the pressure drop compared to the serpentine design is reduced, but the velocity gradient compared to parallel design is also decreased. Since the enhancement of the membrane water content increases the proton conductivity of the membrane, it was observed that the membrane water content in the V-Ribbed design was higher than in conventional designs. The liquid water produced in the V-Ribbed design is about 16.3% and 16.26% lower than in the serpentine and parallel designs. This leads to transporting more oxygen on the catalyst surface and increased average flux density on the cathode catalyst 41.5% and 21.88% compared to serpentine and parallel designs. Finally, it was found that the performance of the fuel cell is enhanced by the V-Ribbed flow channels about 2.19%, and 3.5 % compared to the serpentine and parallel designs, respectively.

The gas absorption process in a Y-shaped microchannel utilizing magnetic nanofluids stimulated within an alternating current magnetic field (AC mf) was studied. Absorption of CO2 at various operation conditions, ferrofluid concentration, and magnetic field strengths were investigated to illustrate the liquid-side overall mass transfer coefficient (KLa), CO2 absorption efficiency (E), nanoparticle enhancement factor (α), magnetic field enhancement factor (γ), and pressure drop (Δp). Furthermore, the position of the microchannel in the magnetic field (i.e. at the top, middle, and down inside the magnetic field) was studied as an effective factor in CO2 absorption enhancement. The position in which the microchannel was held on the top inside the magnetic field reflected more gas absorption compared to the other two positions. While exerting magnetic field strength of 21 mT, 72.2% enhancement was observed in KLa under the optimum conditions.