Optimization of oil-free dynamic sealing performance of high-pressure hydrogen compressors using a novel piston structure

The dynamic sealing performance of the high-pressure cylinder is crucial for the operation of the hydrogen reciprocating compressor. The extreme non-uniformity of contact pressure on oil-free lubricated piston rings increases wear and shortens lifetime of the piston rings. In this study, a new piston structure with through-holes is proposed to even the contact pressure on the gastight rings. The gas leakage model and wear model of piston rings are established to investigate the effect of new piston structure on the wear and leaking efficiency. The results verify that the proposed piston structure can greatly extend the service life of the gastight ring group. The wear rate of the first ring can be reduced by 56% when paired with the proposed through-hole piston. The effect of the through-hole structure on balancing the wear rate of the gastight ring group is subject to the hole diameter. Additionally, the proposed through-hole piston construction is better suited for low molecular weight gas compression when comparing the wear and leakage of rings in hydrogen and nitrogen under the same structure.