Determination of the Mass of Gas in a Reservoir at Filling with a Mixture Component Under the Pressure

The subject of the study is a method for ensuring the mass fraction of a gas mixture when filling a reservoir according to the parameters of a gas component using a mixture generator and a numerical control system for dosing. The aim of the work is the experimental verification of the mathematical model of the unsteady gas-dynamic process of filling the reservoir for use in the method for determining the composition of the mixture. Thus, the Computational Fluid Dynamics (CFD) code CFX-based simulation of filling a reservoir with nitrogen is compared to full-scale experiments. The following results were obtained. The full-scale experiments to determine the pressure and temperature of the gas being filled were carried out with high-frequency monitoring. Models of a gas-dynamic unsteady process for various inlet boundary conditions had been built and compared with each other and experimental data. The difference in pressure between filling models with mass flow control and pressure boundary conditions is up to 10%. The discrepancy between the simulation results and full-scale experiments does not exceed 8% in pressure and 1% in temperature at the monitor point. The use of the SAS SST turbulence model and constant temperature on the wall as a heat transfer condition has been substantiated. It was found that the model with pressure boundary condition on inlet closely matches the reservoir pressure trend over time observed in full-scale experiments, with a typical error of less than 3%, which can provide accurate predictions of gas dosing.