Calibration of a Cryogenic Turbine-Based Volumetric Flow Meter (CTVFM) Using Sub-Cooled Liquid Nitrogen and Solution for Its Practical Issues

The application of cryogenic refrigeration in various applications of superconductivity such as HTS cables, HTS motors, SMES and so on, requires a controlled flow of the cryogens to the superconducting mass. The flow control of the cryogens necessitates the use of a pre-calibrated flow meter to monitor the flow rates and hence maintaining the necessary refrigeration. This paper describes a method to calibrate a Cryogenic Turbine based Volumetric Flow Meter (CTVFM) using sub-cooled liquid nitrogen. The experimental setup along with the procedure has been explained. The paper also discusses the practical issues faced during experiments and remedies adopted to overcome them. Further, the data acquisition (DAQ) system used during the experiment for precise logging of values is discussed. The numerical analysis of the calibration data is carried out and a suitable curve fit along with an equation is obtained to calculate the flow rate from output current of the flow meter transmitter.