In high pressure hydrogen compressor as a renewable energy source, it needs to be compressed to high pressure levels. This article outlines the technical and design features of several classical mechanical compressor technologies (reciprocating, diaphragm, linear) and innovative non-mechanical technologies specifically conceived for hydrogen compression (EHCs, cryogenic compressors, metal hydride and electrochemical). Operating principles and levels of performance of these devices are analysed.
Interstitial metal hydrides (MH) are able to absorb hydrogen at low pressure and desorb it at much higher pressure when heated, making this technology an ideal candidate for an all-in-one one-shot compressor. Moreover, the fact that the same MH may be recharged without contaminating the equipment is highly advantageous in terms of cost and safety requirements.
When used in combination with a thermocouple-based gravimetric hydrogenator, the compressor can be controlled to achieve accurate measurements of hydrogen uptake by the MH alloy. This is done by varying the adsorption temperature by applying liquid nitrogen. This allows the process to be halted at the end of the adsorption cycle by opening a valve at the bottom of the unit, before resuming operation at a lower adsorption temperature.
Efficiency in Motion: Understanding Diaphragm Compressors
When using a mechanical compressor, it is important to design the compressor vessel carefully with a view to avoiding leaking metal and hydride particles. A filter preventing the escaping MH is essential for two reasons: (1) sharp, dehydrided particles can damage valve seats and prevent tight shut-off of the delivery valve; and (2) escaped MH is an unaccounted-for sink/source of hydrogen within the attached system, such as a Sieverts hydrogenator, that could have a deleterious impact on the measured data.