| The special climate such as low pressure,low oxygen,and low temperature on the Qinghai Tibet Plateau seriously affects people’s normal life and work efficiency.Therefore,in addition to meeting the temperature range of human thermal comfort,the indoor environment design of plateau buildings should also consider the issue of plateau hypoxia.Based on the widespread acceptance of air conditioning supply by people at present,it is particularly important to develop a comfortable and healthy indoor heat and oxygen combined supply air supply method based on indoor temperature regulation and further achieving environmental oxygen concentration regulation in response to the requirements for creating special plateau environments.However,existing research on oxygen supply in plateau areas has paid less attention to the physical diffusion laws of oxygen supply airflow,and has not analyzed the mutual influence between hot air flow and oxygen flow.When hot air flow and oxygen flow are combined,exploring the movement and diffusion characteristics of airflow under different air supply parameters is particularly crucial for indoor airflow organization and distribution.It is necessary to obtain corresponding results through mechanism analysis and experimental research,providing corresponding reference basis for creating indoor oxygen and thermal environment in buildings in plateau areas.This study proposes a air supply method for indoor oxygen hot air supply in high-altitude areas.By analyzing the synergistic diffusion characteristics of oxygen hot air flow through jet diffusion theory,the influence of supply air temperature and oxygen concentration on the force of gas jet process is grasped,and the diffusion distribution law of jet gas in the room under different air supply parameters is obtained.This provides a basis for the feasibility and optimization design method of synergistic creation of indoor thermal and oxygen environment in plateau areas.Through CFD numerical simulation and experimental testing,the influence of different air supply parameters on the diffusion process of horizontal and vertical jets of oxygen rich hot air flow was verified.The distribution of indoor air flow organization and the creation effect of oxygen and thermal environment under different indoor air supply methods were compared,and corresponding design basis for oxygen supply and heating was proposed,providing corresponding reference for the design of indoor air flow organization and oxygen supply scheme in plateau areas,Simultaneously meeting the indoor thermal comfort and oxygen comfort requirements in plateau areas.The main results of this study are as follows:(1)Based on fluid mechanics free jet theory,fluid dynamics theory and other theories,the diffusion mechanism of indoor oxygen hot air flow in plateau area is analyzed,and the comprehensive buoyancy of oxygen rich hot air flow diffusion is obtained.The oxygen-enriched hot gas jet undergoes both thermal and mass diffusion,and is subjected to upward temperature difference buoyancy and downward concentration buoyancy.The magnitude and direction of the comprehensive buoyancy are related to the jet temperature,oxygen concentration,and indoor air temperature.When the comprehensive buoyancy is 0,the jet is balanced in the longitudinal direction,and is only affected by the inertial force of the jet.(2)Atmospheric pressure affects the diffusion rate of the oxygen-enriched hot gas flow jet.The lower the atmospheric pressure,the higher the thermal and oxygen diffusion rates of the oxygen-enriched hot gas flow,and the faster the temperature and oxygen concentration of the jet gas decrease.Increasing the air supply temperature has an effect on improving the horizontal jet trajectory.When the jet temperature increases by 3 K～9 K,the jet trajectory increases by 0.6 m to 2.2 m at X=4.0 m.Increasing the oxygen concentration in the jet has a sedimentation effect on the jet trajectory and diffusion range.When the oxygen concentration in the jet increases by 20% to 60%,the sedimentation value of the oxygen-enriched hot jet trajectory at X=3.5 m is 1.3 m to 2.6m.When the double buoyancy is unbalanced,the shape of the diffusion region tends to be asymmetric,and the diffusion area increases accordingly.The effect of flow rate on the diffusion range and area is related to the inlet diameter.The greater the flow rate,the greater the thermal diffusion area and oxygen diffusion area of the oxygen-enriched hot air flow.(3)The increase in jet temperature will cause the vertical jet flow field distribution of oxygen-enriched hot gas to shift upward.When the temperature increases by 3 K～9K,the diffusion region will shift upward by 0.17 m～1.02 m,and the oxygen diffusion area will gradually decrease,and the difference between oxygen diffusion and thermal diffusion area will also decrease.The increase in oxygen concentration in the jet causes the diffusion region of the jet to move downward.When the oxygen concentration increases by 20% to 60%,the diffusion region moves downward by 0.87 m to 1.90 m.The increase in flow rate causes the diffusion area and diffusion area of the airflow to move downward under both constant area and constant speed conditions,and the diffusion area gradually increases with the flow rate.(4)When the oxygen rich hot air supply method is applied to indoor heating and oxygen supply in plateau buildings,the down air supply method has the most significant effect on increasing indoor oxygen concentration.The oxygen concentration at room heights of 1.1 m and 1.6 m has increased by about 3.0% within 30 minutes of oxygen supply time.The indoor temperature at 0.1 m and 1.6 m using the down air supply method increased by about 0.25 K and 0.68 K,respectively,with a better temperature improvement effect than other air supply methods.For the full space oxygen rich hot air supply method in plateau buildings,the lower the height of the air supply outlet,the better the indoor oxygen supply and heating effect.Moreover,while meeting the heating demand,a smaller air supply temperature difference should be selected as much as possible,which is conducive to improving the uniformity of indoor airflow distribution.Based on the theory of fluid dynamics,this study analyzed the forces acting on the oxygen-enriched hot air flow at low pressure in the plateau,and obtained the influencing factors of the jet motion diffusion process;Using CFD numerical simulation method,a diffusion model of oxygen-enriched hot air flow under plateau low pressure conditions was established and analyzed.The effects of atmospheric pressure,jet temperature,oxygen concentration,and flow rate on the distribution of diffusion fields and diffusion regions of horizontal and vertical jets were investigated;Combined with indoor oxygen and thermal environment creation,this paper analyzes the indoor airflow distribution of oxygen enriched hot air flow applied to oxygen supply and heating rooms,and determines that the optimal indoor environment creation effect is achieved by using the appropriate air supply parameters under the air supply mode,providing reference basis for indoor thermal and oxygen environment creation in plateau buildings. |
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