An investigation of fuel cell electrode activity influenced by alternating current electric fields
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Two methods of applying an alternating current electric field to the grid electrodes of the fuel cell systems were studied. Both methods were used to enhance the power output of the system. The alternating current electric field was applied to the grid electrodes to induce greater ionic motion, reduce the concentration polarization losses due to the ionic film double layer, and to desorb catalyst poisons and strongly adsorbed ions from the fuel cell electrode surfaces. The enhancement of the fuel cell system power was found to be a function of the applied voltage and frequency. A greater, applied alternating field voltage resulted in an increased power enhancement. In the first method, a maximum enhancement of 42,000 percent, at an applied voltage of 0.3 volt, was asymptotically approached as the frequency of the alternating current field was increased from 0.5 to 1000 cycles per second. This maximum enhancement corresponded to an output power of 3,000 microwatts. The input power from the alternating field was determined to be no greater than .3,000 microwatts. Also, a retention of the power enhancement for a short period after the removal of the applied alternating field was noticed and measured. In the second method, a maximum enhancement of 670 percent was obtained at an applied voltage of 0.3 volt and a frequency of three cycles per second. A power input of 9,000 microwatts was needed to obtain the 670 percent enhancement. This" power input was much greater than the enhanced power output obtained from the fuel cell system. Grid electrodes were positioned in the gas phase behind the fuel cell electrodes and initial studies indicated that such a configuration consumed negligible input power while still producing an enhanced fuel cell power output. When the effects of the semiconductive materials were investigated, a wafer of n-type silicon was used as the hydrogen electrode and a p-type silicon wafer was used as the oxygen electrode. The open circuit voltage of this configuration was 7.0 millivolts. An open circuit voltage of 4.5 millivolts was measured when the hydrogen electrode was p-type silicon and the oxygen electrode was n-type silicon. The difference between the two configurations indicated that, by assembling the fuel cell system in the same manner as the first configuration considered, an increase in open circuit voltage may be achieved.
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