Numerical analysis of the dynamic two-phase flow behaviour in the ionic liquid compressor for hydrogen refuelling stations

The ionic liquid compressor is a promising compression means for pressure elevation of hydrogen gas in refuelling stations. However, the two-phase flow behaviour of the ionic liquid compressor is unknown, which directly influences the thermodynamic performance of the compressor and therefore is critical for compressor design. Considering the significant effect of the liquid viscosity on the two-phase flow behaviour and the wide range of the viscosity of the ionic liquid, this paper proposed a design method for the ionic liquid compressor and investigated the dynamic flow behaviour during one compression cycle under varied liquid viscosities through numerical simulations. Results found that the number of droplets and the gas vortexes were influenced by the liquid viscosity. Both the highest discharge mass of the hydrogen gas and the lowest discharge mass of the ionic liquid were obtained in the case of 1 mPa∙s. The minimum peak value of the sum of turbulent kinetic energy was observed when the liquid viscosity was 100 mPa∙s. The viscosity of 100 mPa∙s was recommended for the ionic liquid selection under the design conditions considering the flow behaviour, discharged mass, and the sum of turbulent kinetic energy.