Effects of clearances size and fluid medium components on the thermodynamic performance of a claw pump for fuel cell vehicle

Claw-type pump is one of the most promising candidates in the circulating system of the hydrogen fuel cell because of its compact structure and high reliability. In this paper, claw-type hydrogen circulating pump with a rated flowrate of 0.4 Nm³·min⁻¹ was designed and fabricated. An internal flow model of the claw pump was established to investigate the thermodynamic performances with air. Then, a test rig was carried out to validate the feasibility of the numerical model with air. Finally, the numerical model was used to predict the thermodynamic performance with the fluid medium of hydrogen mixtures. Moreover, the effects of axial clearance and the content of water vapor and nitrogen were examined. The results showed that decreasing the axial clearance contributed to the increase in volumetric efficiency, hydrogen mass flow rate, power consumption, and the decrease in specific power. Meanwhile, increasing the contents of water vapor and nitrogen helped to increase the volumetric efficiency and decrease the specific power. However, it had a negative influence on increasing power consumption and decreasing hydrogen flow rate. The specific powers of all the hydrogen mixtures decreased much slower at the smaller axial clearances.