MICROFCELLS - Miniaturization Direct Methanol Fuel Cells: design, modelling and optimization

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Experimental and modeling studies of a micro direct methanol fuel cell

Publication . Falcão, D. S.; Oliveira, V. B.; Rangel, C. M.; Pinto, A. M. F. R.

The Direct Methanol Fuel Cell (DMFC) has attracted much attention due to its potential applications as a power source for transportation and portable electronic devices. Based on the advantages of the scaling laws, miniaturization promises higher efficiency and performance of power generating devices and the MicroDMFC is therefore an emergent technology. In this work, a set of experiments with a MicroDMFC of 2.25 cm2 active area are performed in order to investigate the effect of important operating parameters. Maximum power density achieved was 32 mW/cm2 using a 4 M methanol concentration at room temperature. Polarization curves are compared with mathematical model simulations in order to achieve a better understanding of how parameters affect performance. The one-dimensional model used in this work takes in account coupled heat and mass transfer, along with the electrochemical reactions occurring in a direct methanol fuel cell and was already developed and validated for DMFC in previous work by Oliveira et al. [1–3]. The model is also used to predict some important parameters to analyze fuel cell performance, such as water transport coefficient and methanol crossover. This easy to implement simplified model is suitable for use in real-time MicroDMFC simulations. More experimental data are also reported bearing in mind the insufficient experimental data available in literature at room temperature, a goal condition to use this technology in portable applications.

2015Journal article

Open access

Development and performance analysis of a metallic passive micro-direct methanol fuel cell for portable applications

Publication . Falcão, D. S.; Pereira, J. P.; Rangel, C. M.; Pinto, A. M. F. R.

Due to the growing interest on miniaturization for application on portable devices, the Micro Direct Methanol Fuel Cells (Micro-DMFC) proved to have great benefits. Passive fuel cells have extra advantages leading to less complex and cheaper systems. In the present work, an experimental study on the performance of a passive Micro-DMFC with an active area of 2.25 cm2 working at ambient conditions is described. Several commercially available materials for Membrane Electrode Assembly (MEA) are tested including materials with low platinum content to achieve lower prices. The effect of methanol concentration on the cell performance is evaluated. The performance is compared with the one obtained using an active Micro-DMFC with the same active area. A optimized design is proposed corresponding to a maximum power density, 19.2 mW/cm2, obtained using a Nafion 117 membrane, 3 mg/cm2 Pt–Ru and 0.5 mg/cm2 Pt as, respectively, anode and cathode catalyst loading, carbon paper as anode gas diffusion layer (GDL) and Sigracet carbon paper with micro porous layer (MPL) as cathode GDL at methanol feed concentration of 3 M. This result higher than the optimal power obtained with the active Micro-DMFC clearly demonstrates that membranes with low catalyst content could be used in passive MicroDMFC with success. This is an important result bearing in mind the use of micro-DMFCs in portable applications.

2015Journal article

Open access