Interrupted plate porous media design for ionic liquid-type liquid piston hydrogen compressor and analysis of the effect on compression efficiency

Hydrogen is regarded as an important energy source in the future. A hydrogen compressor is the key equipment in hydrogen-fueled vehicles. The high compression speed leads to the low efficiency for its adiabatic conditions, and the heat transfer condition of the compressor is an important solution. In this study, the porous media installed in the compression cylinder with ionic liquid is proposed to improve the heat transfer conditions and compression efficiency. A mathematical model of heat transfer and fluid resistance in the compression process was constructed. Multiple computational fluid dynamics simulations were applied to summarize the relationship among the Nusselt number, fluid flow resistance, and Reynolds number. Meanwhile, the main influencing factors affecting the convective heat transfer strength of porous media were obtained by analyzing the flow field conditions of fluid basin units in porous media inserts. Then, the relevant mechanism of enhanced heat transfer was proposed. Results show that: all different fluids conform to the quadratic relationship despite the order of magnitude differences in flow resistance. In addition, the Nusselt number is related to the Reynolds number as a power exponential function, and the value of Nusselt number increases as Reynolds number increases. The main heat dissipation surface of porous media is the side of the interrupted plate. Furthermore, the thinner the velocity boundary layer near the wall, the stronger the heat transfer capacity. For a specific compressor at 120 rpm, the porous media designed in this study can reduce the temperature at the end of compression by 14.33 K, saving 11.76% of the unnecessary energy consumption caused by heat dissipation problems.