An innovative water management system for the electrochemical compression of hydrogen up to 10 MPa

An electrochemical hydrogen compressor (EHC) system capable of producing dry compressed hydrogen up to 10 MPa has been developed in this study. The drying system, located downstream of the compressor, consists of a passive countercurrent membrane water exchanger which dries the produced hydrogen flow while simultaneously humidifying the low-pressure hydrogen fed to the compressor. This highly flexible drying system can achieve a dew point temperature of less than-30 degrees C. A dryer structured in this way avoids conventional drying methods such as temperature and pressure swing adsorption cycles, which are very demanding in terms of power and heat rejection. Four proton exchange membranes of different thicknesses were investigated in this study. Hydrogen flows at 10 MPa in the range 0.1-1 mg s- 1 have been obtained using a single EHC. The best performance was obtained with the thinnest membrane, Gore 18 mu m, which allowed reaching a current density of 4 A cm- 2 at 0.4 V and 35 degrees C, with pumped hydrogen flows greater than 0.8 mg s- 1. The efficiency achieved with this system was around 60% at low voltages and current densities, at pressures between 7.5 and 10 MPa. The efficiency was found to decrease with the pumped flow, but the flexibility of this compressor, with its wide range of flow rates and total absence of vibration, should be highlighted.