New serpentine flow field designs of direct methanol fuel cells have been developed to enhance the under rib reactant mass transport without affecting the electronic conductivity to boost up the fuel utilization and fuel cell efficiency. The flow field design is based on three main criteria including the number of paths, the rib lengths, and the flow-path patterning in channels. Therefore, six different flow field designs are developed, including one design with two paths, two designs with three paths and different patterning and rib lengths, and three designs with four paths, different patterning and rib lengths. A threedimensional single phase model for the direct methanol fuel cell is developed, simulated numerically
and validated using the available experimental data. Results revealed that a significant enhancement of fuel cell performance is attained using the new designs. The design with the longest ribs and four paths attains the highest under-rib flows, and the lowest pressure drop between inlet and outlet. Furthermore, the power density has shown a 52.9% and 35.8% increase using an enhanced serpentine flow field with four paths compared to the conventional serpentine flow field design, at 0.5 M and 0.25 M inlet methanol concentrations. Using the new designs allows for the operating of the direct methanol fuel cell at a lower methanol concentration without a significant reduction of the output power