Establish traceability for liquefied hydrogen flow measurements

Abstract

The EU aims to be climate-neutral by 2050 and usage of liquid hydrogen (LH2) for transportation is expected to grow fast. With the expected uptake, traceability in custody transfer is required. Existing metrological infrastructure can be used to provide traceability with basic calibrations performed typically under ambient conditions. However, due to the very challenging LH2 process conditions, with temperatures as low as 20 K, there is a need to determine the flow measurement uncertainty at these process conditions. Within the Joint Research Project (JRP) 20IND11 "Metrology infrastructure for high-pressure gas and liquified hydrogen flows" (MetHyInfra) [1], traceability for liquefied hydrogen flow measurements is developed by a three-pronged approach: (I) assessment of transferability of water and LNG calibrations to LH2 conditions; (II) cryogenic Laser Doppler Velocimetry (LDV) adapted to LH2 flow applications; (III) assessment of transferability of water, liquefied nitrogen, and liquefied helium calibrations in the vaporisation method to LH2 conditions. In this paper the initial MetHyInfra project results are presented comprising: (I) description of LH2 flow meters, water and LNG calibration results, analytical model prediction statements of uncertainty at LH2 conditions when calibration is performed under ambient conditions, finite element numerical modelling analysis of various thermal effects affecting CFMs at LH2 conditions, (II) design modifications of cryogenic LDV to ensure operability at LH2 conditions, (III) description of the vaporisation standard. It was found that obtaining a definite quantitative number of liquefied hydrogen flow measurement uncertainty from the analytical model is challenging for a variety of reasons.

Metrology infrastructure for high-pressure gas and liquified hydrogen flows

“…Here, a three-pronged approach for traceable flow measurement of liquefied hydrogen using flow calibration facilities is applied: (I) assessing the transferability of water and liquefied natural gas (LNG) calibrations to liquefied hydrogen conditions (see Figure 11); (II) To evaluate the transferability of calibrations using water, liquefied nitrogen and liquefied helium in the vaporization process to liquefied hydrogen conditions (see Figure 12); (III) novel cryogenic laser Doppler velocimetry (LDV) adapted to liquid hydrogen flow application, which can be used either as a primary standard or as a secondary standard for liquid hydrogen flow measurements (see Figure 13). More details on the three approaches and the challenges of transferability of a water calibration is shown in another paper of MetHyInfra [13].…”