Hydrogen compression by means of an electrochemical cell (EHC) is a very efficient and innovative technology for high pressure hydrogen storage, meanwhile efficient small size gas compressors able to withstand low power Polymer Electrolyte Fuel Cell (PEFC) stack conditions are hard to find on the market. They are also quite inefficient, noisy, produce undesired vibrations and pulsation. Thanks to its modularity, simplicity and the use of most of the fuel cell technology parts and design, the EHC (Electrochemical Hydrogen Compressor) can be used also for hydrogen recirculation within a Polymer Electrolyte Fuel Cell (PEFC) stack. In such a case, the pressure drop is usually very low (0,5-1 bar) while operative conditions (pressure, flow, temperature and relative humidity) are mostly influenced by the stack. In this work, the behaviour of two different membranes (a reference Nafion NR212 and a in-house manufactured composite Ni-TiOx) has been studied to optimise the operation at low pressure and give design input for an integrated stack-EHC unit. The experimental results show that the composite membrane gives better performance than the thinner Nafion NR212 thanks to its water retention properties, also giving evidence that the largest energy loss is due to the membrane resistance. The best operative conditions are then to operate at low current density, increasing the active area of the MEA (membrane and electrode assembly) and the overall EHC size.
Performance assessment of composite membranes for low pressure electrochemical hydrogen compressors
Fabio Matera;Ada Saccà;Irene Gatto
2016
Abstract
Hydrogen compression by means of an electrochemical cell (EHC) is a very efficient and innovative technology for high pressure hydrogen storage, meanwhile efficient small size gas compressors able to withstand low power Polymer Electrolyte Fuel Cell (PEFC) stack conditions are hard to find on the market. They are also quite inefficient, noisy, produce undesired vibrations and pulsation. Thanks to its modularity, simplicity and the use of most of the fuel cell technology parts and design, the EHC (Electrochemical Hydrogen Compressor) can be used also for hydrogen recirculation within a Polymer Electrolyte Fuel Cell (PEFC) stack. In such a case, the pressure drop is usually very low (0,5-1 bar) while operative conditions (pressure, flow, temperature and relative humidity) are mostly influenced by the stack. In this work, the behaviour of two different membranes (a reference Nafion NR212 and a in-house manufactured composite Ni-TiOx) has been studied to optimise the operation at low pressure and give design input for an integrated stack-EHC unit. The experimental results show that the composite membrane gives better performance than the thinner Nafion NR212 thanks to its water retention properties, also giving evidence that the largest energy loss is due to the membrane resistance. The best operative conditions are then to operate at low current density, increasing the active area of the MEA (membrane and electrode assembly) and the overall EHC size.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
