Synergistic parametric optimisation of gas–liquid interaction with valve lift and liquid column in an ionic liquid hydrogen compressor

Ionic liquid hydrogen compressors serve as vital components for hydrogen refueling stations, where gas valves act as core elements. The self-acting valve in the compressor chamber has several control parameters, and the characteristics of the ionic liquid column also affect the two-phase flow within the cylinder. The self-acting valve and the fluctuations of the liquid column jointly exert an influence on the compression process. This study investigates the influence of three critical design parameters on isothermal efficiency, valve delay closure time, and liquid discharge volume. Among these, valve lift predominantly governs the valve delay closure time. Subsequently, a multi-objective optimization analysis integrating these three performance metrics is conducted. By adopting grey relational analysis (GRA), the study derives the optimal design parameter configuration. Results show that the optimized parameters are: valve lift of 2 mm, ionic liquid density of 1800 kg/m³, and initial liquid piston height of 30 mm. This work uniquely targets valve lift and ionic liquid density to balance valve dynamics and liquid carryover, which lays a foundation for gas valve design in ionic liquid compressors and ionic liquid selection while offering extendable insights for exploring other influencing factors and design considerations under diverse operating conditions.