Question

3.1 Draw a sketch showing the typical Gaussian pattern of the atmospheric dispersion of an airborne plume. Show maximum concentration, wind speed and stack height. Give the 6 assumptions of the Gaussian plume model (10)

3.2 What problem is created by buoyant stack emissions? (5)

3.3 During the December summer holidays, the N3 from Johannesburg to Durban carries 30 000 cars per hour for 13 hours of daylight, (15 000 per hour each way) at an average speed of 120 kmh-1. Each vehicle emits 0.09 g.s-1 of CO. The wind speed during the day is 2 m.s-1 and increases to 4 m.s-1 when the sun sets. During the 11 hours of darkness, the traffic subsides and the number of cars decreases to 10 000 per hour (5 000 per hour each way). Calculate the average CO concentration experienced by people residing

within 1 km of the highway during the day and at night.

Assume - the emissions from the vehicles occur at ground level

- emissions occur at the centerline of the highway. - the concentration upwind of the highway is zero.

AQC4701/101/0/2019

Answer 1

The answer to the above mentioned question is below in form of images :-

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Plume Centerline oly tant Conceitartior ion → He at xz He at atXi He Hs = Adua0 Stack. Height He- Eppective Sack Height = pollutaufrelease haght 2i0 Ah = plume γ。se
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