Thermodynamics of Hydrogen; Analysing and Refining of Critical Flow Factor Through Comprehensive Uncertainty Assessment and Experimental Data Integration

Abstract The calibration of flow meters that used in hydrogen transformation needs a reliable reference device such as sonic nozzles Therefore, critical flow factor (C*) for hydrogen must be calculated precisely through existing equations that is why it is important to investigate the achievable uncertainty in calculating this vital parameter. In addition, the quality and accuracy of thermophysical property experimental/modelled data plays a vital role in reaching the highest accuracy determination of C*. Therefore, in this study, an examination of the literature has been undertaken to target experimental measurements related to pure hydrogen, setting the stage for a comprehensive gap analysis followed by analysing various available equation of state models in predicting accurate thermophysical properties of pure hydrogen. We introduced new high pressure high temperature (HPHT) Fluid Property Test Rig to add new reliable thermophysical property data to the literature and also we presented C* values and validated our calculations with two calibration gases: nitrogen, and methane and their standardised C* values. Then, C* values for hydrogen were generated using this verified methodology in the context of the expanding role of sonic nozzles in hydrogen flow meter calibration. This study showed that C* calculations can be enhanced significantly by using the representative equation along with employing appropriate thermodynamic equations of state which are examined by high accurate new measured experimental data.