Numerical Simulation And Experimental Study Of Dissemination And Purification Of Gaseous Pollutants In Stadiums

Large amounts of formaldehyde and other volatile organic compounds emanated from plates and other decoration materials caused a serious deterioration in indoor air quality, and affected the health of people and the competition state of athletes in the new stadiums, so it was very meaningful to research the effective way to improve the air quality such as dilution with ventilation and use of air purifiers. In this paper, through the application of numerical simulation software "Fluent", the dissemination and dilution or purification of pollutants represented by formaldehyde was simulated, and through simple experiments to verify the reliability of the results, so that the simulation results could be applied to engineering practice.Firstly, the principles and methods of calculation of the CFD was expound from the perspective of the mathematical theory in this paper, and then the double exponential decay model was selected which was suitable to short and long emitted term of pollutants, and the dissemination model was embedded in the Fluent software through the UDF. Based on this method, the dissemination and purification efficiency of formaldehyde of the stadium in different conditions was simulated by the CFD combined with the actual situation of a new stadium in Wuhan in the next few chapters. Specific content and results of this paper were as follows:1. A new stadium in Wuhan was simulated and studied in closed condition, the results show that with the increase of the closed time, the pollutants continued to spread and the concentration of the pollutants was increasing. After one hour, the concentrations of pollutants exceeded indoor health standards in part of the region at the plane that z=1.5m, and after twelve hours, the concentration of most of the tournament region and part of the audience area was excessive.2. The concentration and velocity field of pollutants were predicted and analyzed in the case that the air supply rate was unchanged, and the air supply angles were mutative which including0°,30°,45°and60°separately tend to audience area and competition area. The results showed that the concentration of pollutants increasing at the beginning ten minutes and began to decrease between ten and fifteen minutes, and sixty minutes later it almost unchanged, while the pollutant removal efficiency of vertical ventilation was the best and the air purification effect was getting worse with the increase of air supply angle, so the vertical ventilation was the best choice. 3. The change of concentration field of pollutants for different air supply rate (4m/s,6m/s and8m/s) was studied in vertical ventilation conditions, results showed that with increasing of air velocity, the purification effect improved more or less at starting stage, but the final effect was not obvious, and did not meet the requirements of wind speed in small ball games.4. In the case of vertical ventilation and designed air supply rate, three purifiers were selected active area, two conditions that placed the purifiers decentralized and side by side were simulated, and came to the conclusion that when purifiers decentralized the purification efficiency improved through their purification function and promotion of air distribution, which saved thirty minutes than individual ventilation to drop the concentrations of pollutant within the health standards. And it had little effect on air distribution when purifiers were placed side by side, and the purification effect themselves was limited, so the promotion of purifying effect was not obvious. Then the indoor velocity field was simulated in various conditions, the results showed that the air velocity in vertical ventilation conditions met the design requirements of the competition area. Therefore purifier can be used as auxiliary purification measures before the game to reduce the running time of air conditioning system before the game to save energy.5. Twelve measuring points were evenly arranged in the competition area, and the pollutant concentration values at the surface that z=1.5m was measured in the closed condition, the results showed that the simulated and measured values were substantially the same trend in addition to individual points, and the reliability of the simulation could be verified, that provided a reference for the prediction of other pollutants in different large spaces and provided the basis for engineering practice.