Development and Testing of a Roots Pump for Hydrogen Recirculation in Fuel Cell System

In this paper, the development and testing of a Roots pump with a new rotor profile for hydrogen recirculation in the fuel cell system are presented. The design method of the rotor profile, port position, and structure of the pump is presented. A prototype of a three-lobe Roots pump with helical rotors was fabricated, and its performance was experimentally tested. The measured data show that the effect of the pressure difference on the flow rate and volumetric efficiency of the Roots pump is the most significant, while the effect of suction pressure is limited. It is concluded that the leakage rather than flow resistance is the key factor, which has a major influence on volumetric and isentropic efficiency. The comparison of the performance is also given by the measured results of the same Roots pump working with air, helium, and hydrogen. Finally, the successful integration of the Roots pumps into three PEM fuel cell systems is reported and the optimal operating parameters of the Roots pump in the systems under various loads are also presented. It is found that the performance of the Roots pump integrated into the fuel cell system is better than that measured with pure hydrogen on the test rig. The performance maps composed of all the measured data of the Roots pump are very helpful for the optimal design and operation of the fuel cell system.