Objective Supercritical CO₂ is widely used in new energy systems and Carbon Capture, Utilization and Storage (CCUS) processes. As a critical link between capture and storage, the compressor experiences severe supercritical CO₂ pulsations during the exhaust process, causing pipeline vibrations that may lead to structural fatigue and pipeline damage in severe cases. Therefore, analyzing and optimizing gas pulsations in supercritical CO₂ reciprocating compressors is essential to enhance system stability and safety.

Methods A numerical simulation method based on the real-gas equation of state was employed to systematically analyze the effects of exhaust conditions and pipeline structure on gas pulsation characteristics of the supercritical CO₂ reciprocating compressor using multiple sets of typical operating parameters. Pulsation responses under varying exhaust pressures, temperatures, CO₂ mass fractions, and pipe diameters were compared, and a parameter design method leveraging the filter tube structure model was proposed.

Results The gas pulsation of supercritical CO₂ exhibited distinct characteristics compared to conventional gases. Turbulent pulsation was more likely to form due to its high density and low viscosity. At an exhaust pressure of 30 MPa, the pulsation amplitude was significantly higher than that of CH₄, displaying a pronounced double-peak structure. As the exhaust pressure increased from 10 MPa to 30 MPa, both pressure non-uniformity and pulsation energy in the exhaust pipeline rose markedly, increasing pipeline vibration. When exhaust temperature rose from 403 K to 453 K, the system was more prone to resonance at 403 K and 413 K, with gas flow disturbances intensifying. Increasing the CO₂ mass fraction expanded pulsation amplitude without altering peak frequency, thereby raising resonance likelihood. Structural parameters significantly influenced pulsation control, evidenced by that the pressure non-uniformity and pulsation energy were effectively reduced when the exhaust pipe diameter increased beyond 160 mm, though peak frequency was minimally affected. Controlling the filter tube diameter at around 40 mm balanced pressure loss and pulsation suppression.

Conclusion This study identifies the key factors and mechanisms influencing gas pulsation in supercritical CO₂ reciprocating compressors, proposes a control strategy based on optimizing pipeline structural parameters, and offers theoretical support for the design and safe operation of supercritical CO₂ compression systems.