Diffusion characteristics of oxygenic–thermal coupled airflow in high-altitude sleeping environment

About 1/3 of human life is spent sleeping. The hypoxic and cold environment in high-altitude areas leads to sleep disorders that are more prominently harmful to the human body. To improve the quality of human sleep in high-altitude areas, this study explored the thermal and oxygen environment regulation for plateau sleep. In this study, the influencing factors of the diffusion of oxygenic–thermal coupled airflow were determined through the theoretical analysis of a thermal fluid mechanic jet. This study used computational fluid dynamics (CFD) to investigate the diffusion characteristics of the oxygenic–thermal coupled airflow with a sleeping experiment conducted on the plateau. The results showed that the influence of the thermal plume at 0.1 m near the human face was larger, and the oxygenic–thermal coupled airflow diffusion process was mainly divided into three phases over time. The size and time to stabilize the oxygen volume fraction in the inhalation zone varied between conditions and were strongly influenced by the temperature difference of the supply air. The effects of the thermal and oxygen environment were analyzed using indicators such as facial-area speed ratio, draft risk, and personal oxygen inhalation efficiency. The optimal design strategies were recommended with an outlet air velocity of 1.5 m/s, a temperature difference of 8 K between the outlet airflow and the indoor background air, and an outlet oxygen volume fraction of 30%. The results can provide implications for regulating the thermal and oxygen environment to improve human sleep quality in high-altitude areas.