微流道气-液两相流研究及其在PEMFC中的应用进展

Research progress of gas-liquid two-phase flow in micro-channel and its application in PEMFC

微流道由于具有比表面积高、传质能力强等优点,已成功地应用于化工领域的多种气-液反应体系中。此外,其在化工领域中的研究成果还可以应用于目前备受关注的燃料电池领域以提高其电化学转化效率。然而,微流道尺度的微小化以及其中气-液两相流规律的复杂性使得微流道内的气-液两相流特性的阐明还需要进一步的研究,才能促使微流道在实际应用中发挥更优异的作用。本文从流型、压降和传质三个关键特征的研究角度来介绍微流道内气-液两相流的研究进展,简述了不同流型的特征及其形成条件,阐明了其对应的压降大小和传质能力的高低,回顾了现有的压降和传质系数的预测模型及其相应的优化措施,并分析了运用这三个关键特征的相关参数来优化质子交换膜燃料电池流场设计方面的研究进展,得到了流场类型、流道尺寸、流道形状、流道表面特性等的优化方案。但是,燃料电池中的精细流道的特殊结构及其特定工况使得其与传统的微流道有显著的区别。由此,本文提出了应当根据燃料电池精细流道的特点探明其中的两相流型、压降和传质的动态变化规律以及构建相应的压降预测模型的建议,以期为流场设计提供更准确的参考依据,进而提高燃料电池性能,加速燃料电池的商用进程。

Micro-channel has been successfully applied in gas-liquid two-phase chemical reaction system due to its high specific surface area and strong mass transfer ability.In addition,the research achievement in the field of chemical engineering can also be utilized to improve the fuel cell electrochemical conversion efficiency.However,due to the small scale of micro-channel and the complexity of gas-liquid two-phase flow rules,further study is required to clarify the characteristics of gas-liquid two-phase flow in micro-channel,which can promote it to perform better in practical applications.In this paper,the research progress of the critical characteristics as flow patterns,pressure drop and mass transfer are illustrated.Moreover,the features of different flow patterns and its forming conditions are described,while the corresponding pressure drop and mass transfer capacity are expounded.According to this relationship,readers can get the design parameters and the necessary operated condition to achieve the expected flow patterns which can cost low pressure loss and provide great mass transfer ability.The existing prediction models of pressure drop and mass transfer coefficient and their optimization measures were reviewed.Moreover,the research progress of improving the performance of proton exchange membrane fuel cell(PEMFC)flow field design by using the relevant parameters of these key characteristics were analyzed.Base on that,the optimum proposal toward flow field type,channel size,channel shape,channel surface characteristics can be obtained.However,due to the special structure and working condition of the fine flow channel in PEMFC,it shows great different from the traditional microchannel.Therefore,it was suggested that the two-phase flow patterns,the dynamic change law of pressure drop and mass transfer should be explored aiming at the special characteristics of the fine flow channel of fuel cell,and the specific pressure drop prediction model should be developed.The further study suggested would provide a more accurate reference for the flow field design,and then enhance the performance of PEMFC,accelerate its commercialization process.