Design of gravimetric primary standards for field-testing of hydrogen refuelling stations

• The Federal Institute of Metrology METAS developed a Hydrogen Field Test Standard (HFTS) that can be used for field verification and calibration of hydrogen refuelling stations. The testing method is based on the gravimetric principle. The experimental design of the HFTS as well as the description of the method are presented here. The HFTS has been tested at METAS with nitrogen gas at −40 °C to mimic a refuelling process in the field. Laboratory tests have shown that icing on the pipes of the HFTS have a non-negligible impact on the results. Field-testing with the HFTS has also been performed at the Empa hydrogen refuelling station with hydrogen at up to 70 MPa. The major uncertainty components have been identified and assigned values. The required expanded uncertainty of 0.3% could be achieved. A detailed uncertainty budget has been presented and shows that the scale is the largest contributor; buoyancy corrections only play a minor role. For the lowest uncertainty measurements, appropriate waiting times or cleaning methods to get rid of icing are required. © 2020 The Authors

Nyckelord

Gravimetric method

Hydrogen calibration

Hydrogen dispenser

Budget control

Uncertainty analysis

Cleaning methods

Field verifications

Hydrogen refuelling stations

Laboratory test

Primary standards

Testing method

Uncertainty budget

Uncertainty measurements

Hydrogen

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ref (ämneskategori)

art (ämneskategori)