Quantitative Analysis of Energy and Power on Direct Methanol Fuel Cell Systems

Report No. ARL-TR-3458
Authors: Rongzhong Jiang and Deryn Chu
Date/Pages: April 2005; 30 pages
Abstract: Two commercial direct methanol fuel cell (DMFC) systems, designed with the same power (25W) but different sizes (size ratio in 11 to 1), were evaluated by constant current discharge at various current loadings and environmental temperatures. Quantitative analysis of fuel consumption and energy output was achieved by a simple mathematical treatment of the experimental data. The larger DMFC system gives higher energy density (770 Wh/Kg) than that of the smaller one (450 Wh/Kg) based on the fuel weight. The smaller DMFC system has higher power density (15.3 W/Kg) than that of the larger one (3.5 W/Kg) based on system weight. Heat dissipation is attributed to be the main problem of limiting the discharge performance for the smaller DMFC system. Too high and too low ambient temperature will cause the energy density to decrease for the DMFC systems. The desire ambient temperature for the present DMFC systems is 20-30 oC. The length of operation time for the DMFC systems also affects the energy output. Minimum time (varying with experimental conditions) is needed for the DMFC system to reach a maximum power and energy output.
Distribution: Approved for public release
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Last Update / Reviewed: April 1, 2005