Molecular dynamics insights into contaminant phase transition and regenerator blockage mechanisms

• Develop a continuous contaminant injection MD model for regenerator simulation. • Fewer than 5% of contaminants pass through the mesh below phase-change temperature. • Reveal distinct adsorption behaviors of three gases (N 2 /CO 2 /H 2 O) on wire mesh. • Discover migration of frost layers after desublimation on wire mesh. Pulse Tube Refrigerators are widely used in cryogenic applications due to their high reliability and long lifespan. However, the release of contaminant gases from internal components, which leads to performance degradation, remains a challenging issue. This study employs molecular dynamics simulations to analyze the behavior of N 2 , CO 2 , and H 2 O within the regenerator. The results indicate that as the temperature decreases, more contaminants desublimate and deposit. Below the phase transition temperature (T pt ), more than 95 % of contaminants deposit within 3 mesh layers. For H 2 O above the T pt , over 98 % attaches to the wire mesh during airflow passes through. N 2 forms a monolayer on the wire surface, while CO 2 at 140 K and H 2 O at 220 K exhibit solid growth on the windward side, with these solids being transported to regions of lower airflow velocity as temperatures rise. Additionally, solid contaminants can sublimate into gas, diffusing toward colder regions. Lower temperatures reduce the likelihood of resublimation occurring. There is less than a 2 % ratio that N 2 and CO 2 will sublimate at 80 K and 180 K, and the migration distance is N 2 > CO 2 > H 2 O. This study provides a theoretical foundation for improving regenerator design and restoring the performance of degraded refrigerators.