Condensation phenomena in fuel cell systems for aviation - KONBREFF

航空燃料电池系统中的冷凝现象 - KONBREFF

• 批准号: 498604607
• 负责人: Professor Dr.-Ing. Jens Friedrichs
• 金额: --
• 依托单位: Institut für Flugantriebe und Strömungsmaschinen (IFAS)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/498604607?language=en
• 关键词: Condensation; phenomena; fuel; cell; systems

A major component of polymer electrolyte fuel cell systems is the cathode system. It provides ambient air at an optimal pressure level to the fuel cell stack. The central component of the cathode system is a turbocharger with compressor, electric drive and a turbine for utilizing the enthalpy of the fuel cell outflow. The fuel cell outflow and thus also the turbine inflow are almost or completely saturated with water vapor. Expansion in the turbine initially leads to supersaturation of the water vapor and then to condensation of water droplets. This process, and in particular the condensation enthalpy released in the process, have a significant influence on the aerodynamics and performance parameters of the turbine.In a current research project at the Institute of Jet Propulsion and Turbomachinery, a high-fidelity Euler-Lagrange approach for the numerical modeling of multiphase flow in the turbine of an automotive fuel cell turbocharger could be developed. The results show that condensation can lead to significant thermal throttling of the turbine, as well as efficiency losses. However, the simultaneous increase of the turbine outlet temperature by up to 50 K provides a significant performance potential for downstream turbine stages. This is particularly interesting for aerospace applications, where multi-stage turbines have to be used due to the higher pressure ratios. However, turbines with condensation are so far only known from stationary applications with low power density requirements. The question to be addressed in this project is therefore:What are the fundamental effects of condensation on the performance, efficiency and optimum operating point of the turbine stages of an aerospace fuel cell turbocharger with very high gravimetric and volumetric power density requirements? What are the dominant mechanisms and how can they be accounted for as reduced-order models in turbine and system design?To answer these research questions, numerical investigations are to be carried out on the basis of the already validated and tested Euler-Lagrange approach. First of all, a turbine with two radial stages will be designed for an aviation reference system. The focus is on a design that is as small and light as possible. Subsequently, the optimal operating points for exemplary flight altitudes are considered and investigated with respect to their condensation phenomena. The results and findings of the proposed project form an important basis for the future development and design of fuel cell turbochargers suitable for aviation and for the calculation of their system behavior.

聚合物电解质燃料电池系统的主要部件是阴极系统。它为燃料电池堆提供最佳压力水平的环境空气。阴极系统的中心部件是具有压缩机、电驱动器和用于利用燃料电池流出物的焓的涡轮机的涡轮增压器。燃料电池流出物以及因此涡轮机流入物几乎或完全被水蒸气饱和。涡轮机中的膨胀最初导致水蒸气的过饱和，然后导致水滴的冷凝。这个过程，特别是在该过程中释放的冷凝焓，对涡轮机的空气动力学和性能参数具有显著影响。在喷气推进和涡轮机研究所的一个当前研究项目中，可以开发用于汽车燃料电池涡轮增压器的涡轮机中的多相流的数值模拟的高保真欧拉-拉格朗日方法。结果表明，冷凝可导致涡轮机的显著热节流以及效率损失。然而，涡轮机出口温度同时增加高达50 K为下游涡轮机级提供了显著的性能潜力。这对于航空航天应用特别有意义，其中由于较高的压力比而必须使用多级涡轮机。然而，迄今为止，具有冷凝的涡轮机仅在具有低功率密度要求的固定应用中已知。因此，本项目中要解决的问题是：冷凝对具有非常高的重量和体积功率密度要求的航空航天燃料电池涡轮增压器的涡轮机级的性能、效率和最佳工作点的基本影响是什么？主导机制是什么？如何将它们视为涡轮机和系统设计中的降阶模型？为了回答这些研究问题，数值研究的基础上进行的已经验证和测试的欧拉-拉格朗日方法。首先，将为航空参考系统设计具有两个径向级的涡轮机。重点是尽可能小而轻的设计。随后，典型的飞行高度的最佳操作点被认为是和调查方面的冷凝现象。该项目的结果和发现为未来开发和设计适用于航空的燃料电池涡轮增压器及其系统性能的计算奠定了重要基础。