ENV4204 S1 2017 Assignment One
Gaussian Dispersion Problem
Assistant Examiner : Ian Craig Due Date consult ENV4204 studydesk Marks : 150/1000
1) The emission of NO2 from a coal fired power plant chimney stack has been assessed by an environmental engineer. The data collected is as follows :- i) chimney height 150m, ii) diameter 2m, iii) pollutant gas exit velocity 7 m/s, iv) gas exit temperature 250°C, v) atmospheric pressure 106kPa, v) ambient air temperature 29 °C, vi) emission rate 80g/s. Assuming a windspeed of 3m/s, what would the ground level centreline concentration be, on an overcast summer afternoon, 4km downwind of the stack ?
2) In the case of part (1), what would the air concentration of the pollutant be, experienced by an airliner, flying at 3,000 feet, 10 km downwind, and 1km off the plume centreline ?
3) What other air pollutants are normally experienced by people living in London and surrounding areas ?
4) Assuming a normal emission scenario from the London Area Source (you now have to have to model this, using multiple line sources). Assume that the pollution source emission area is defined as the area of London as encircled by the M25 motorway. What typical ground level air pollutant concentrations would normally be experienced by people living near Old Warden Aerodrome Biggleswade, located approximately 80km north of the centre of London. Ignore pollution sources outside the M25 motorway defined area. Perform area source modelling in excel to illustrate your answer. Use the Line Source Variant (LSV) of the Gaussian Dispersion equation, and overlap the result to simulate accumulated air concentrations downwind of the source area.
For supporting background information, you can look at :-
Submit two files (using Moodle Assignment Submission Area) as follows :-
1) Excel spreadsheet file (this will only be looked at briefly)
2) Written report pdf (insert relevant graphs into your report, and describe what they mean in the text. Use detailed numbered figure captions).
Answer/Criteria Max mark Category Actual mark
1 Accuracy of answer 1 30
2 Accuracy of answer 2 30
3 Accuracy of answer 3 15
4 Accuracy of answer 4 15
5 Spreadsheet overall effort and organisation 30
6 Report presentation, spelling, grammar, references etc.
Note: Category 1 - not satisfactory: Category 2 - barely satisfactory: Category 3 - good: Category 4 - excellent