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A novel design for an ethanol injection system has been proposed, which consists of one pump chamber, two valves, and one central-vibrating piezoelectric device. The system uses a microdiaphragm pump with a piezoelectric device for microdirect alcohol fuel cells. The diameters of the pump chamber are 31 mm and 23 mm, and the depths of the chamber are 1 mm and 2 mm. When the piezoelectric device actuates for changing pump chamber volume, the valves will be opened/closed, and the ethanol will be delivered into DAFC system due to the pressure variation. The chamber dimensions, vibrating frequencies of the piezoelectric device, and valve thickness are used as important parameters for the performance of the novel ethanol injection system. The experimental results show that the ethanol flow rate can reach 170 mL/min at a vibrating frequency of 75 Hz. In addition, the ethanol flow rate is higher than the water flow rate.

Previous studies of a bi-cell piezoelectric proton exchange membrane fuel cell with a nozzle and diffuser (PZT-PEMFC-ND bi-cell) have shown that the performance of the PZT-PEMFC-ND bi-cell could be 1.6 times greater than that of the single cell when the proper aspect ratio (AR) of 11.25 and the diffuser angle of 5° are applied to the diffuser. In this study, the novel pseudo-bipolar bi-cell module was designated parallel with an 8 cm2 reaction area, an AR of 5.63, and a diffuser angle 10°. The bi-cell module was operated under various operating conditions, including different operating temperatures, bi-cell circuit and intake module on anode, the performance of the bi-cell and the two component cells, and to optimize the integrated system output. The pump performance of the PZT-PEMFC-ND may be influenced by the asymmetric amplitude of the PZT device. The asymmetric amplitude results in different air flow rates through the cathode chamber of the component cells and in different current outputs for the component cells. For the different intake modules, the power of bi-cells at flow parallel and series will produce maximum power as 0.283 W cm−2 and 0.263 W cm−2, respectively. The power consumption of the PZT device should be taken into consideration when determining the net power of the PZT-PEMFC-ND bi-cell. In this study, the maximum net power of the bi-cell was found to be 0.7W.