Research Of The Poison Gas Diffusion And Controlling Methods On Emergent Events In Large Space Buildings

When the emergencies happen due to accident fire or poison gas made by people in the large space of public buildings, the most of casualties are hurt by toxic gas inhaled. Once the poison gas spreads in large spaces, it is very difficult to control and will result in severe harm and consequences. Besides the characters of the poison gas, the damage to person's body lies on the concentration of poison gas and the duration of staying in poison gas. Therefore, we must effectively control the diffusing range of poison gas and reduce its concentration in the evacuation route way, ensuring that people indoor can arrive to safe places during the minimum time and the damage to person becomes as minimal as possible. Based on study on mechanism of poison gas' free diffusion, this paper researches the different technologies of emergent ventilation and their capabilities of controlling the poison gas diffusion under the different modes of public emergences occurring in the large space of public buildings. Meantime, the paper has developed the technologies of emergent ventilation which can keep away many modes of public emergences and different poison gas. The research work includes as follow:1. The types of poison gas, the damage to person made by poison gas and the characters of the poison gas diffusion are systematically set forth when public emergences happen, which are implemented under main modes (such as the poison gas made by setting fire, by gas bomb attack or by artificially distributing toxic substance directly) occurring in the interior of large spaces building. The applicability and shortages of the current up-exhaust technology of emergent ventilation are analyzed in controlling the poison gas diffusion in the large space building. On basis given above, the control-exhaust model technology of emergent ventilation, which can control the poison gas diffusion in the local area and discharge the poison gas completely, are put forward.2. According to the movement characteristic of air flow and poison gas in the large space, A numerical simulation method for unsteady low-speed flow N-S equations with preconditioned method has been developed. This method can eliminate stiffness of the equations in low-speed flow.3. According to the movement characteristic of poison gas in the large space, the research schemes combine both numerical simulation and experimental study. The mode of setting fire is studied through the method of small-scaled model salt-water experiment. The modes of gas bomb attack or artificially distributing toxic substance are researched through the method of numerical simulation. A numerical simulation method for unsteady low-speed turbulence flow equations and species transport equation with preconditioned method has been developed.4. Using the method of numerical simulation, under the modes of artificially distributing toxic substance, the characteristic of the poison gas free diffusing in the interior of large space buildings, and the effect of the poison gas diffusing implemented by the doors, barriers and so on are investigated.5. Using the method of numerical simulation, under the modes of artificially distributing toxic substance, the characteristic of the poison gas diffusing in the steady ventilating airflow indoor, and the effect on the ventilating and air-conditioning system transporting poison gas to the other area indoor are investigated.6. Using the method of numerical simulation, the ability to control poison gas diffusion and the transportation process adopting the conventionally up-exhaust technology of emergent ventilation or control-exhaust model technology of emergent ventilation in the large space building are studied. The effects on controlling the poison gas diffusion under different flow parameters of supply air or exhaust air are researched. It has been verified by numerical simulation that the control-exhaust model technology of emergent ventilation is correct and feasible. It can overcome the shortage that the up-exhaust technology lacks applicability to different poison gas, which offers new design idea and technological means in designing the emergent ventilation engineering of a large space building.7. Using the method of small-scaled model salt-water experiments, the flow pattern of the fire smoke and the developing process of the thickness of smoke layer in the large space building under the conditions of no smoke exhaust, smoke natural exhaust and smoke mechanical exhaust are researched. At the same time, the flow field of the indoor air is tested applying the PIV technology.