Numerical Analysis of the Dynamic Two-Phase Flow Behavior in the Ionic Compressor with a Novel H-shaped Piston

With the development of the hydrogen energy industry, it is crucial for hydrogen refueling stations that compressors can work efficiently and flexibly with a longer life span. Adopting ionic liquid as a liquid piston to compress hydrogen is a feasible method. The high stroke frequency of ionic compressor prevents the liquid piston from maintaining a stable shape, leading to the generation of the additional clearance volume and hydrogen sealing failure. In this article, a novel H-shaped piston was proposed and a 3D numerical model of an ionic compressor cylinder with it was established. The dynamic simulation of the two-phase fluid behavior in the cylinder during three cycles was performed using the volume of fluid method and the dynamic mesh technique. The effect of this piston on the variation of the two-phase interface and the clearance volume of the compressor has been discussed for optimizing the design of the ionic compressor. Results show that: the clearance volume of the cylinder with a H-shaped piston was smaller than that of the cylinder with a normal piston in all three compression cycles, which indicated that the higher volumetric efficiency could be obtained with the H-shaped piston. In addition, the application of the H-shaped piston allowed sufficient ionic fluid to be retained in critical sealing locations of the cylinder to keep hydrogen sealing and piston lubrication well.