Experimental study on initial pressurization of Cryogenic Reciprocating Pump Systems

The cryogenic reciprocating pump (CRP) is a device used to increase the pressure of cryogenic liquefied gases and has gained attention as a key component of eco-friendly fuel gas supply systems (FGSS) aimed at achieving sustainable development goals. Despite considerable progress in the commercialization of CRPs, academic research in this area remains relatively lacking. This study established a pilot-scale liquid nitrogen CRP system and conducted experimental investigations into the pressurization mechanism of the CRP under various operating conditions. It was observed that the liquid nitrogen became subcooled during pressurization, suggesting that pressure-driven condensation may outweigh vaporization caused by compression heating under the present conditions. The results further show that, even under identical external temperature and pressure conditions, gravity-induced variations in fluid quality critically affect CRP performance. Moreover, vertical storage geometries, which provide hydrostatic head, naturally maintain a higher degree of subcooling, whereas horizontal layouts (e.g., in airliners, ships, and refueling stations) demand additional measures to secure this margin. Based on these findings, an in-depth analysis of the CRP pressurization mechanism is provided, along with a system configuration strategy for improving CRP performance.