APPLICATION OF VALVE-LESS IMPEDANCE PUMPS TO A DIRECT SODIUM BOROHYDRIDE-HYDROGEN PEROXIDE FUEL CELL

In this study, two novel valve-less impedance pumps are applied, for the first time, in the liquid fuel supply of a Direct Sodium Borohydride Hydrogen Peroxide Fuel Cell (DBHPFC). This valve-less pump prevents the pump corrosion and serves appropriately to reduce the volume and weight of fuel cell systems. It comprises an amber latex rubber tube, connected at both ends to rigid stainless steel tubes of different acoustic impedance, and a simple actuation mechanism which combines a small DC motor and a cam. The motor activated cam periodically compresses the elastic tube at a position asymmetric from the tube ends. Traveling waves, emitted from the compression, combine with reflected waves at the impedance-mismatched rubber tube/stainless tube interfaces. The resulting wave interference creates a pressure gradient and generates a net flow. A DBHPFC with the active area of 25 cm(2) is constructed. It is shown that the maximum pumping rate can achieve 30 ml/min with the DBHPFC connected. The corresponding maximum power and current are 13.0 W and 25.5 A, respectively. Specific power, volumetric power density, and back work ratio of the DBHPFC using this pumping method are shown superior to those of the other pumping configuration with the peristaltic pumps.