大气污染控制工程--Lecture 6-2 Air Pollutant Concentration Models.ppt

Air Pollution Control Engineering Prof. Jiakuan Yang Huazhong University of Science and Technology Lecture 6 Air Pollutant Concentration Models (4) Gaussian plume , two-dimensional spreading equation (4) Gaussian plume , two-dimensional spreading equation (4) Gaussian plume , two-dimensional spreading equation (4) Gaussian plume , two-dimensional spreading equation 沿着Z方向的正态分布 (4) Gaussian plume , two-dimensional spreading equation (5) Gaussian plume equation considering reflection effect of the ground (5) Gaussian plume equation considering reflection effect of the ground (6 ) ground-level concentration Ⅳ Other topics about Air pollutants transporting Ⅳ Other topics about Air pollutants transporting Ⅴ Summary (1) Fixed-box models – qualitatively Gaussian plume models – point sources , quantitatively Ⅴ Summary Ⅴ Summary Ⅴ Summary The Gaussian plume diffusion model there are three important equations for Gaussian plume , two-dimensional spreading . Ⅴ Summary Example 6.4 A factory emits 20g/s of SO2 at height H . Wind speed is 3m/s . At a distance of 1km downwind , the values of σy andσz are 30m and 20m ,respectively . What are the SO2 concentrations at the centerline of plume ,and at a point 60 meters to the side of the centerline and 20 meters below the centerline . Example 6.4 Example 6.4 This Lecture and the Next Lecture Homework DISCUSSIONS * Ⅰ What is Air pollutant Concentration Model? Ⅱ Fixed-box model Ⅲ Gaussian Diffusion Model Ⅳ Other topics about Air pollutants transporting Ⅴ Summary ② The first term is the concentration on the centerline of the plume . ③ three terms of Gussian plume equation First term, when y = 0 , ( z – H) = 0, so exp 0 = 1 With the increase of downwind distance(x), c on centerline is decreasing. Second term 1 c The second term shows how the concentration decreases as we move in the horizontal. Diffusion in y direction. Third term Diffusion in z direction. The same as the second term. y Z x 10