Experimental investigation and modelling of the air compressor performance used for hydrogen fuel cell systems under enhanced cooling conditions

Water cooling is a critical thermal management strategy for ensuring the reliable operation of electric air compressors in high-power hydrogen fuel cell systems. However, the heat transfer at gas–solid interfaces during motor cooling introduces significant discrepancies between the experimentally measured compressor performance map (MAP) and design-phase predictions. With the purposes of solving the experimental MAP distortion, the coupling effects of aerodynamic performance and liquid cooling strategies under various cooling conditions were investigated. The performance MAPs of each compression stage and the overall stage were analysed. Furthermore, a streamlined semi-empirical prediction method for the temperature and pressure ratio correction was developed based on experimental data with and without water cooling. The accuracy of the proposed models was validated against experimental data, and the models were further applied to predict and extend the MAP across extreme operating conditions. Results indicated that the additional heat dissipation expands pressure ratio and isentropic efficiency to the distortion region, particularly in the low thermal inertia range. Upon the development and execution of the prediction models, the maximum mean square error (MSE) for the validation set of each stage outlet temperature prediction was 9.83 × 10⁻⁴ and 3.08 × 10⁻⁴, respectively. The predicted pressure ratio aligned closely with non-cooled test results, with a maximum relative error of 0.1 %. At water temperatures of 30 °C and 40 °C, the regenerated MAP exhibited highly consistent gradient characteristics and quantitative features.