Dispersion Models Dispersion of pollutants in the atmosphere Models Gaussian Dispersion Model Effective stack height Area and line sources

Introduction Connection between Source and Atmosphere Emissions of pollutants from sources Air quality in the atmosphere Emission Air Quality Connection: MODELS Very wide variety of models

PLUME DISPERSION

What is MODEL? A mathematical relation (equation or a set of equations) to estimate some parameter(s) (i.e. Outputs) by using some other set of parameter(s) (i.e. Inputs) MODEL Yj = f(Xi) Input(s), Xi Output(s), Yj

The Gaussian plume model The present tendency is to interpret dispersion data in terms of the Gaussian model. The standard deviations are related to the eddy diffusivities

FIXED Box model Consider a rectangular city as shown. To compute the air pollution concentration , use the following form :

FIXED Box model If there is no creation rate , then :

FIXED Box model Where: b: is the background concentration at X-0 entering the city in g/m3 c: concentration in the entrie city

FIXED Box model Example : A city has the following decryption: w= 5km, L= 15km, u= 3m/s, H= 1000 m. the upward or background concentration of carbon monoxide is b= 5 ug/m3 , the emission rate per unit area is q= 4x10-6 g/s.m2 . Determine the concentration of carbon monoxide for the city.

Point of Maximum Concentration The maximum concentration downwind occurs along the plume centerline. For point on the plume centerline the following

Example : A power plant located in rural area burns 10 tons of coal per hour containing 3 percent sulfur. The effective stack height is 150 meters. Determine the maximum concentration of sulfur dioxide if : Surface wind sped= 2.5 m/s Sun angle 20 degrees Cloud conditions: clear Downwind distance less than 5000

Example : A large , poorly controlled copper smeller has a stack 150 m height and plume rise of 75 m. it is currently emitting 1000 g/s SO2. estimate the rotund level concentration of SO2 from this source at a distance of 5 Km directly downwind when the wind speed is 3 m/s and the stability class is C.

Example : The management of the smelter in previous example has been informed that the concentration calculated in that example at that location and for those concentrations is twice the allowable. They propose to remedy this situation by installing a higher stack . How high must this stack be so that the estimated concentration will be exactly one half that in in previous example. Plume rise is the same as previous example.

Example : A ground level source (H=0) is estimating pollutants at an unknown rate. At 1 Km directly downwind of the source the measured gr4ound level concentration of the pollutant is 10 µg/m3 . The stability category is A. estimate the emission rate of the source.