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Unformatted text preview: Atmospheric Transport Examples Lecture# 32 Air Transport: M: Ch 7 (pg. 392-418) in course notes pack ICP #29: Downwind Concentrations of Emissions due to Power Plants ICP #30: Calculation of Peak Downwind Concentration What you should have learned: Air Transport Examples How do you calculate down wind pollutant concentration for a power plant of known coal combustion characteristics? (ICP #29) What is sensitivity analysis and why do we perform it? How is the location of maximum pollutant concentration actually discovered? (ICP #30) The Gaussian point source dispersion equation describes the ground level (z=0) pollution. Concentration created by the point source. C(x,y) = concentration at ground level at point (x,y) in units g/m 3 x = distance directly downwind, m y = horizontal distance from the plume centerline, m H = effective stack height, m Q = emission rate of pollutants, g/s u H = average windspeed at effective stack height, m/s y (x) = horizontal dispersion coefficient, a standard deviation, m z (x) = vertical dispersion coefficient, m Gaussian Model Equation = 2 2 ) ( 2 2 exp ) ( 2 2 exp ) ( ) ( ) , ( x y x H x x u Q y x C y z z y H Gaussian Plume Model Dispersion Coefficients Y Z Wind Direction Graphical Determination of Dispersion Coefficients Based on Ambient Weather Conditions Y Z Distance from Source Distance from Source very unstable very stable Numerical Estimation of Dispersion Coefficients To aid calculations, empirical approximations have been established for specific sections of the curves. y (x) = ax 0.894 z (x) = cx d + f x is in km! Atmospheric Stability stability attributes lead to classification scheme (A-F) for atmospheric stability based on daytime intensity of solar radiation, nighttime extent of cloud cover, and near-surface wind speed A: very unstable B: moderately unstable C: slightly unstable D: neutral E: slightly stable F: stable Determining Atmospheric Stability Class Windspeed For the determination of dispersion coefficients, the surface windspeed is required (defined as windspeed at elevation of 10m)....
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This note was uploaded on 04/17/2008 for the course CEE 260 taught by Professor Kimf.hayes during the Fall '06 term at University of Michigan.
- Fall '06