Effects of baffle position in serpentine flow channel on the performance of proton exchange membrane fuel cells

Abstract

This study used a three-dimensional numerical model of a proton exchange membrane fuel cell with five types of channels: a smooth channel (Case 1); eight rectangular baffles were arranged in the upstream (Case 2), midstream (Case 3), downstream (Case 4), and entire cathode flow channel (Case 5) to study the effects of baffle position on mass transport, power density, net power, etc. Moreover, the effects of back pressure and humidity on the voltage were investigated. Results showed that compared to smooth channels, the oxygen and water transport facilitation at the GDL-Channel interface were added 11.53%−20.60% and 7.81%−9.80% at 1.68 A·cm−2 by adding baffles. The closer the baffles were to upstream, the higher the total oxygen flux, but the lower the flux uniformity and the worse the water removal. The oxygen flux of upstream baffles was 8.14% higher than that of downstream baffles, but oxygen flux uniformity decreased by 18.96% at 1.68 A·cm−2. The order of water removal and voltage improvement was Case 4 > Case 5 > Case 3 > Case 2 > Case 1. Net power of Case 4 was 9.87% higher than smooth channel. To the Case 4, when the cell worked under low back pressure or high humidity, the voltage increments were higher. The potential increment for the backpressure of 0 atm was 0.9% higher than that of 2 atm. The potential increment for the humidity of 100% was 7.89% higher than that of 50%.