Repeatability of the master meter method in calibrating compressed hydrogen dispenser

Abstract

Hydrogen fuel cell technology is an important development direction of clean energy vehicles, which has the characteristics of zero pollution and renewability. As a key role in the commercial operation of hydrogen energy vehicles, the accuracy of the hydrogen filling quantity directly affects trade fairness and market promotion. The master meter method is generally used for the flow calibration of the existing compressed hydrogen dispenser, tin other words, high-precision Coriolis mass flowmeter is connected in series to the hydrogen filling pipeline on site, and the calibration is completed in the actual hydrogen filling process. In practice, it was found that compared with CNG, the compressed hydrogen filling process was added with a pre-charging and pressure maintaining procedure. If the model of the master meter and flowmeter in the compressed hydrogen filling dispenser to be calibrated are different, the repeatability of the calibration result will be poor. It is preliminarily concluded by experiments and analysis that the error is caused by the response of Coriolis mass flowmeter of different types to the single pulse flow during pre-charging and pressure maintaining procedure, which affects the repeatability of calibration of master meter method. Finally, it is suggested that the mass accumulated in the stage of the pre-charging pressure maintaining should not be included in the error calculation when the master meter method is used to calibrate compressed hydrogen dispenser.