Characteristics of Critical Nozzle Flow Meter for Measuring High-Pressure Hydrogen Gas

Abstract

The critical nozzle flow meter was developed for high-pressure hydrogen gas flow measurements, and its characteristics was experimentally examined with hydrogen gas at the pressure up to 70 MPa. The results show that the critical back pressure ratio is 0.93-0.95 under the above pressure conditions, and its discharge coefficient has a curious behavior which the discharge coefficient decreases with increasing the Reynolds number over 40 MPa. Also, tests filling hydrogen gas into the storage tank of fuel cell vehicle was conducted under 35 MPa condition with the developed flow meter, and the high efficiency of this flow meter was confirmed even on practical uses.