Experimental investigation and simulation of the Flow Comparator prototype as new primary standard for high pressure natural gas in Germany
The Flow Comparator is a development of a new primary standard for calibration of high-pressurenatural gas metersby the German national metrological institute, Physikalisch-Technische Bundesanstalt. The Flow Comparator uses an actively driven piston which isbased on the comparator principle to measure the flow rate by measuring the time the piston needs to displace a defined volume of enclosed gas in a cylinder. A scale model is used to test the system. Based on this,a computational model is developed for deeper understanding of the Flow Comparator’s dynamic behavior and the interaction with other components in the system. It allows to gather detailed information at any location of the system as well as testing different configurations and parameters of the system components. The validation of the developed computational model shows good accordance with measured piston velocity and differential pressure at the piston. The model is used to optimize the control voltage trajectory applied to the piston to maximize available calibration time and to improve the overall calibration process.