Analysis of Planar Membraneless Micro Fuel Cell Performance
Date Issued
2006
Date
2006
Author(s)
Lin, Mu-Kun
DOI
zh-TW
Abstract
ABSTRACT
The transport of oxygen, the cell performance and oxidant utilization in the planar membraneless microchannel fuel cell (PM2FC) are considenred by numerical simulation in this study. The physical model including the mass transport, the flow and the electrochemistry is simulated by commercial software CFDRC. The fuel is formic acid dissolved in dilute sulfuric acid solutions. Then the oxidant is oxygen dissolved in dilute sulfuric acid solutions. Both fuel and oxidant streams enter and flow in parellel through the microchannel. In the microchannel the occurrence of laminar flow separates both streams and eliminates the need of a membrane. This study solves governing equations through finite volume methode. It considers the effects of the flow, the concentration, and the geometric size of the system to examine the transport of oxygen, the cell performance and oxidant utilization of the PM2FC and to find singnificant parameters helpful to the cell performance. The results are helpful to the design of PM2FC.
The results show that the cell performance of PM2FC is mainly restricted by the transport of oxygen in the cathode, which can be improved significantly by using higher flow rate or oxygen concentration, or a thicker catalyst layer. However, the effects of the flow rate and thickness of catalyst layer are limited, which is limited by the low transport of the cathode electrode. It signifies that two parameters must exist optimal conditions. Besides, the geometry of the microchannel is an important parameter to improve the cell performance. To change the length or width of the microchannel is equal to change the reaction area, which makes the current and power of the fuel cell increase. The thickness of the microchannel influences obviously the ohmic losses and oxidant utilization. The thiner mirochannel has less ohmic losses and better cell performances but tends to have the fuel crossover, which we need high flow rate to prevent. However at the same velocity the thiner microchannel offers less flux of the oxidant stream, the cell performance increases because of more ohmic losses. Then oxidant utiliztion increases.
Subjects
無膜燃料電池
微型燃料電池
Membraneless micro fuel cells
Miro fuel cells
Type
thesis
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