Optimization design methodology of large flow hydrogen recirculation system for megawatt polymer electrolyte membrane fuel cell

Polymer electrolyte membrane fuel cell is a potential technology in megawatt-scale hydrogen power generation for its advantages of green energy and high efficiency. However, the conventional low-capacity hydrogen circulation system is difficult linear amplification to the megawatt fuel cell system because the nonlinear characteristics requirements of the large mass flow rate. This study presents a large-flow and high-performance ejector hydrogen supply and recirculation system to synchronously meet requirements of megawatt fuel cell systems by exploring the nonlinear relationship between the geometric parameters and the system power. This paper proposes an optimization design methodology for the large-flow and high-performance ejector and investigates its operating characteristics under variable operating conditions. Multiple operating points are introduced into the optimization design of the ejector. The methods of bidirectional iteration and multi-objective optimization on the working conditions and structural parameters are adopted to achieve large mass flow rate and high entrainment performance of the ejector. The performance variation trend of multiple operating points and the optimal entrainment performance of each point are comprehensively considered to maintain the stable operation of the ejector within a certain operating range. The error between the designed large-flow and high-performance ejector for the anode hydrogen recirculation system and stacks is less than 5% among the working condition range of pressure from 0.9 to 1.8 MPa through experimental verification. The designed large flow hydrogen recirculation system achieves a high and stable entrainment performance for the megawatt polymer electrolyte membrane fuel cell in wide operating conditions.