Passive control of the concentration boundary layer in microfluidic fuel cells using Dean vortices
Passive control of the concentration boundary layer in microfluidic fuel cells using Dean vortices
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DOI：
10.1007/s10404-019-2274-2
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发表时间：
2019-08
影响因子：
2.8
通讯作者：
Wiebke Rösing;T. Schildhauer;J. König;C. Cierpka
中科院分区：
文献类型：
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作者：
Wiebke Rösing;T. Schildhauer;J. König;C. Cierpka
微流体燃料电池受到电极处浓度边界层形成的限制，导致低功率密度和低燃料利用率。这项工作展示了一种新的方法，以提高扩散限制的质量传输，通过使用迪恩涡减小浓度边界层的大小。这些涡流是由弯曲的微通道引起的，并增强了新鲜反应物向电极的质量输送。数值模拟表明迪恩涡对微流控燃料电池性能的影响。此外，一个弯曲的微流控装置与分段电极的制作，它允许实验研究的影响，增强扩散限制的质量传输模型氧化还原对的电流密度，从而证明的概念和数值结果。它示出的迪恩涡流，在弯曲的通道中发展，导致对流运输的新鲜的溶液朝向电极产生高电流密度，并导致在使用弯曲的微流体燃料电池，而不是一个直的30%的改善。在扩散和对流质量传输平衡的条件下，这种方法不仅有更高的功率密度，而且有更高的燃料利用率。
Microfluidic fuel cells are limited by the formation of concentration boundary layers at the electrodes, resulting in low power density and low fuel utilization. This work demonstrates a novel method to enhance the diffusion-limited mass transport by decreasing the size of the concentration boundary layer using Dean vortices. These vortices are induced by a curved microchannel and enhance the mass transport of fresh reactant towards the electrodes. Numerical simulations were performed to show the influence of the Dean vortices on the performance of a microfluidic fuel cell. Furthermore, a curved microfluidic device with segmented electrodes was fabricated, which allows to experimentally investigate the effect of the enhanced diffusion-limited mass transport on the current density of a model redox couple and thus to prove the concept and the numerical results. It is shown that the Dean vortices, evolving in the curved channel, cause a convective transport of fresh solution towards the electrodes yielding a high current density and resulting in an improvement of 30% using a curved microfluidic fuel cell instead of a straight one. On condition that diffusive and convective mass transport are well-balanced, this approach promises not only a higher power density, but also a much higher fuel utilization.