Study of Novel Pseudo-bipolar Bi-cell Piezoelectric Proton Exchange Membrane Fuel Cells with Nozzles and Diffusers
Date Issued
2011
Date
2011
Author(s)
Wang, Jyun-Sheng
Abstract
An innovative design for a piezoelectric proton exchange membrane fuel cell with nozzle and diffuser (PZT-PEMFC-ND) using pseudo-bipolar design is developed to achieve a higher power in the stack design to solve water-flooding problems and improve cell performance. This new design, with a reaction area of 8 cm2, contains two cells with two outside anodes and two inside cathodes that share a common PZT vibrating device for pumping air flow. The influence of the varying aspect ratio (AR) of the diffuser elements on the unit cell-flow rate is investigated using a three-dimensional transitional model. The simulation results show that a proper AR value of 11.25 for the diffuser, with a smaller diffuser angle of 5°, could ensure a smoother intake of the air and, thus, better cell performance. The experimental results show that the performance of the PZT-PEMFC-ND bi-cell can be 1.6 times greater than that of the single cell. Furthermore, this novel design is shrunken by using a reduced nozzle and diffuser. This reduced bi-cell should be operated with a larger hydrogen stoichiometric ratio of 1.5, a cell temperature of 50 °C and a humidified hydrogen temperature 30 °C to prevent a serious concentration loss. Moreover, the performance of the bi-cell using one degraded membrane electrode assembly (MEA) and one normal MEA is investigated to understand the current flow characteristic of the bi-cell. Although an internal current is observed, the bi-cell can still deliver a non-negative power. The power consumption of the PZT device is temperature-dependant and this should be taken into consideration when determining the net power of the PZT-PEMFC-ND bi-cell. The maximum net power of the bi-cell is found to be 0.7W.
Subjects
piezoelectric
fuel cell
nozzle
diffuser
air-breathing
pseudo-bipolar
Type
thesis
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