Review and analysis of hydrogen recirculation devices for compact vehicular proton exchange membrane fuel cells

In vehicular fuel cells, hydrogen recirculation devices are employed to improve efficiency and solve anode flooding problems. For motor-driven compressors, problems such as high-power consumption, leakage (claw, roots), high noise (claw, roots), high manufacturing costs (scroll, slide), wear (claw, roots, scroll), low lifetime (diaphragm, centrifugal, partial discharge), high speeds (centrifugal), low efficiency (regeneration, partial discharge), stalling and surging (centrifugal) severely limit their utilization. Compared with traditional mechanical connections, magnetic transmission innovatively breaks through the pollution problem. For high-pressure-hydrogen–driven ejectors, the single ejector and some of its derivatives’ working range cannot meet the entire fuel cell conditions, necessitating the use of a compressor or injector. Meanwhile, the control of expansion–compression integrated machines driven by high-pressure hydrogen and cathode-tail gas is complicated. Due to the disadvantages of complex systems, slow response times, and high costs, the pressure swing recirculation method and surge tanks are not suitable for vehicular fuel cells. Placing the ejector in parallel with a regenerative compressor combines the advantages of each, with ability to cover the entire range of operating conditions in line with future directions and developmental targets.