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This study investigates the effect of various configurations of a hydrogen ejector on fuel efficiency in a fuel cell, with a focus on increasing hydrogen recirculation using a concave configuration with a helical pattern.

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System
MFC

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Abstract

Abstract Renewable energy such as hydrogen or solar energy is promising due to issues surrounding environmental pollution. In particular, hydrogen only produces water and generates electric energy in a fuel cell when reacting electrochemically with air. A fuel cell consists of many parts such as a cell stack, an ejector, a hydrogen tank, and a regulator, and so on. In this study, the ejector, a device that supplies hydrogen to proton exchange membrane fuel cell (PEMFC), is studied. The ejector recirculates unreacted hydrogen in proton exchange membrane fuel cells by the Venturi effect. Since the ejector is related to energy efficiency, many researchers have conducted research to improve the performance of the ejector. Therefore, it is most desirable that hydrogen recirculation in the ejector is increased. The present research investigates how the configuration of the ejector affects the hydrogen recirculation. A concave configuration of the ejector is considered. This concave having a helical pattern is dependent on a pitch ratio and the number of grooves. The results are compared with numerical analysis data from existing publications using computational fluid dynamics (CFD). The influence of the configuration was analyzed by performing numerical simulations with three-dimensional grid systems. A poly-hex-core mesh type was applied to reduce errors caused by convection and diffusion in the computational domain. Considering the configurations of the ejector, turbulence dissipation rate, static pressure, and tangential velocity inflow were analyzed graphically. Consequently, it was determined that the model displays a 7% increase in recirculation ratio over the reference model.

Key findings

  • The concave configuration with a helical pattern increases hydrogen recirculation compared to existing configurations.
  • The pitch ratio and number of grooves in the concave configuration significantly affect the hydrogen recirculation rate.
  • Numerical analysis confirms the experimental results, indicating a potential improvement in fuel efficiency.

Keywords

InjectorProton exchange membrane fuel cellHydrogenHydrogen fuelStack (abstract data type)Computational fluid dynamics

Identifiers

DOI
10.1115/gt2021-60334
Journal
Volume 6: Ceramics and Ceramic Composites; Coal, Biomass, Hydrogen, and Alternative Fuels; Microturbines, Turbochargers, and Small Turbomachines
Year
2021