Stable operation of air-blowing direct methanol fuel cell stacks through uniform oxidant supply by varying fluid flow fixtures and developing the flow sensor

Air-blowing type direct methanol fuel cells (DMFCs) are becoming more attractive for portable electronic devices as alternatives to the currently used Li-ion batteries because they are quieter with less parasitic power loss than the active-type DMFCs used a compressor. However, the blower has difficulty in providing a uniform air supply with a high flow rate to the cathode manifolds of the stack. In this study, a design that allows accurate measurements of the flow distribution on the air-blowing DMFC stack is developed using a novel scientific approach and careful construction of the experimental apparatus. Using this novel experimental technique, a novel stack design is produced to improve the performance and stability of the DMFC system under air-blowing conditions. Furthermore, auxiliary devices, such as ducts, guide vanes, foams, membrane and wedges are integrated and evaluated to the stack to assist in uniform flow by the blower. In particular, the inlet foam, membrane and upper angle duct help improve the uniformity of the lateral and longitudinal flow distribution in the air-blowing stack. Finally, the air-blowing stack with these auxiliary devices shows high performance with operational stability.

► Stable operation of DMFCs with a high power density is possible under air-blowing conditions with flow aid apparatus.
► The inlet foam, membrane and upper angle duct play a key role in improving the flow uniformity of the stack cathode.
► This might be due to the increased pressure difference in the cathode manifolds by the flow resistors.
► A design that allows accurate measurements of the flow distribution on the air-blowing DMFC stack is established using a novel scientific approach.