Numerical investigation on the wave transformation in the ionic liquid compressor for the application in hydrogen refuelling stations

The ionic liquid compressor exhibits excellent advantages in hydrogen refuelling stations due to the specific design based on the hydraulic system and the ionic liquid piston. The application of the ionic liquid column results in a complex two-phase flow issue inside the compression chamber. This two-phase flow behaviour is critical for the compressor design as it influences the wave dynamics during the compression, but it is absent in the open literature. In this paper, transit numerical simulations were carried out to investigate the wave transformation during a compression cycle by the volume of fluid (VOF) method under different heights of the ionic liquid piston. The effect of liquid height on the wave transformation, discharged quantity of ionic liquid and hydrogen gas, and the turbulence kinetic energy was analysed. The minimum crest value of the turbulent kinetic energy was observed as 0.54 kJ in the cases of 30 and 40 mm. The optimal height of the ionic liquid piston was recommended 40 mm under the presented design condition based on the simulation results.