Improved momentum exchange theory for a regenerative-type hydrogen recirculation blower in vehicular PEMFCs

The regenerative blowers, with their compact structure and stable performance at low flow rates, are well-suited for hydrogen recirculation in fuel cells operating under low-power conditions, particularly when paired with ejectors. However, the momentum exchange theory exhibits significant deviations when predicting the blower performance at high flow coefficients. This study investigates the limitations of the momentum exchange theory. Numerical simulations and theoretical analyses were conducted to examine the inlet/outlet area ratio (A1/A2) and velocity centroids (r1 and r2) of the circulatory flow, and the effects of operating conditions, vane width, and flow channel width on these parameters were also studied. Two nondimensional parameters, the ratio of vane width to vane height and the ratio of flow channel width to vane height, were introduced to refine the prediction of r1 r2 and A1/A2, resulting in an improved momentum exchange theory. Validation with experimental data demonstrated enhanced prediction accuracy for flow coefficients above 0.23. Specifically, at flow coefficients of 0.424 and 0.475, the corrected model improved accuracy by 9.39 % and 13.39 %, respectively. Consequently, the overall average prediction accuracy of the corrected theory was improved. This study advances the accurate performance evaluation of similar regenerative blowers.