Air-independent propulsion (AIP) submarines carry huge quantities of liquid oxygen. However, in the liquid oxygen combustion process, the cold energy is not usually recovered, and there are criticisms concerning CO₂ removal in the confined space of a submarine. Aiming at the two major pain points that have long plagued AIP submarines, this paper proposes an integrated solution that organically combines the recovery and utilization of cold energy from liquid oxygen with the removal of CO₂ .

Liquid oxygen can be used as a cold energy source to process the cabin air. According to the different phase transition temperature characteristics of each air component, the CO₂ in the air is frozen (condensed) and separated under normal pressure.

This study uses quantitative data analysis to show that the energy stored in liquid oxygen can basically meet the cold energy demand for freezing the CO₂ produced by the crew's respiratory metabolism within the self-sustaining capacity of the submarine, and proposes a three-level workflow and implementation plan.

The technical solution proposed in this paper can recycle 5% of cold energy from liquid oxygen, which conforms to the idea of the comprehensive integration of energy saving and noise reduction, and the full integration of overall resources. As such, it can be used for air purification and CO₂ removal in confined spaces such as submarines, submersibles and deep-sea space stations powered by AIP systems.