CFD analysis and conjugate heat transfer modeling of ionic compressors

Abstract

Ionic compressors are promising applied in hydrogen refueling stations. Ionic liquid covers a solid piston for sealing and cooling. It is necessary to investigate flow and heat transfer processes inside the cylinder. This study performs a two-phase CFD simulation incorporating valve motion by dynamic mesh method. Results show that the flow through the valves enhances heat transfer over the liquid surface. It is hard to transform the compression stage into an isothermal process, which is attributed to the low velocity of hydrogen flow. The liquid surface produces relatively severe deformation when the piston moves downward, since the flow through the suction valve impinges on the liquid surface. Furthermore, a novel conjugate heat transfer (CHT) model is proposed for calculating heat transfer between hydrogen and ionic liquid, which has a good agreement with the CFD results. Ionic liquid can decrease the hydrogen temperature at the initial stage of a multi-cycle process. The cooling effect of the ionic liquid abates as its temperature increases. This study can provide a technical reference for fast calculation of gas-liquid heat transfer of ionic compressors.