Two-phase flow characteristics within the ionic liquid compression chamber under different Mach numbers of the self-acting valve

The emerging ionic liquid compressor represents advanced compression technology for high-pressure hydrogen refueling stations. The self-acting valve is the core component in the cylinder of the reciprocating compressor, as it directly affects the operational performance of the ionic liquid compressor; however, the influence of the valve structure on the two-phase flow and compressor performance is unknown. This study combined a two-phase flow model with valve motion to explore the two-phase compression characteristics influenced by self-acting valves. The liquid fluctuation and gas velocity field in the compression chamber were analyzed when different structural self-acting valves that have different valve Mach numbers were arranged on the compression chamber, and then the valve motion and fluid suction and discharge performance were investigated. The results indicated that considering the pressure loss through the valve and the accuracy of opening and closing of the valve disk, the lowest possible Mach number is preferable; however, in terms of hydrogen exhaust temperature and loss of ionic liquid in the discharge procedures, larger Mach number is better. This research provides a foundation for optimizing the valve design of the ionic liquid compressor suitable for two-phase compression and guides future research on improving compressor performance and energy efficiency.