Experimental study on a metal hydride based hydrogen compressor

Abstract

A three-stage metal hydride based hydrogen compressor prototype was built. It has been designed for a hydrogen production facility using a low-pressure alkaline electrolyser. The compression system should transfer heat recovered from the electrolyser into the hydride beds to allow hydrogen desorption flow. The three-stage compressor achieves a compression ratio of 20:1 atm. It performs a thermal cycling of three AB5 hydrides between 20 and 80 °C. Its flow rate, for 25 g of each hydride bed, reaches about 20 l (NTP) of hydrogen per hour. The prototype is now operational. Some improvements in the heat transfer management system are also carried out before proceeding to the interconnection with the electrolyser and to the extent that the hydrogen produced satisfies the high purity requirement of the hydrides used in the compressor.