In-situ calibration method of orifice flow meter equipped in 600 W helium refrigerator/liquefier with variable temperature supplies

Abstract A 600 W helium refrigerator/liquefier with variable temperature supplies was constructed in the National Institute for Fusion Science (NIFS). The mass flow rate of supply Supercritical Helium (SHe) is important information for its performance tests and experimental uses. A quarter circle orifice, according to Verein Deutscher Ingenieure and Verband Deutscher Elektrotechniker (VDI/VDE) 2041, is equipped as a mass flow meter. In the case of the configuration of our system, it is recommended to calibrate the orifice under identical operation conditions with regard to Reynolds number and installation. Therefore, a new in-situ calibration method of the orifice is developed. A dummy heat load was attached between SHe supply and return ports, and the resulting SHe enthalpy rise gives us the information for a mass flow rate. The obtained coefficients of discharge are consistent with those of previous studies.