Serial electrochemical hydrogen compressor stack for high-pressure compression

In this study, a serial electrochemical hydrogen compressor (EHC) stack was designed to compress hydrogen gas to hundreds of bars. The operating parameters were examined to analyze optimal performance. First, a serial stack was designed to enable the EHC to operate at pressures exceeding hundreds of bars. The circular design of the stack was chosen specifically to prevent hydrogen leakage. A 127-mu m-thick membrane was selected owing to its relatively good pressure resistance and performance. Through a serial EHC stack of 3 cells, hydrogen was pressurized over 120 bar. A parametric study showed that the pressure-ratio across the membrane barely affected the performance. Additionally, the higher the temperature and relative humidity, the better the performance. By increasing the temperature to 70 degrees C, the power consumption was reduced by 40 %. At 100 % relative humidity, the EHC exhibited the lowest power consumption. Finally, the performance of the serial stack was analyzed under optimal operating conditions, wherein it demonstrated an efficiency over 64 % for below 0.03 kg/day mass-flow rate of compressed hydrogen. However, efficiency decreased to 12 % at a mass-flow rate over 0.17 kg/ day.