Using OP-FTIR to Localize Emission Sources in Ambient Environment
Date Issued
2008
Date
2008
Author(s)
Chen, Ching-Hui
Abstract
An experimental field trial for tracing back two gaseous emission sources upwind was conducted to simulate the real situations of occurring leakages in the industrial estates. There are four innovative aspects in this study. First, two emission sources, N2O and SF6, were localized simultaneously in this study. Secondly, we investigated three different methods to process the PIC data and applied three basis functions, which are normal, beta and weibull basis functions, to reconstruct 1-D profiles with a set of PIC data. Thirdly, the uncertainties of 1-D profile reconstructions were considered in this study. Fourthly, we introduced a new approach by applying Monte Carlo method to predict the peak locations along the measurement line without reconstruction procedures. ombining the peak locations of air pollutants concentrations along a measurement line downwind of monitoring area with wind directions can trace back the upwind emission sources. Two approaches are introduced to find the peak locations in this thesis. First approach is to reconstruct the 1-D profiles along the measurement line to obtain the reconstructed peak locations. Second is to find the possible peak locations within the region of highest segmented PIC by Monte Carlo method along the measurement line. In order to investigate the applications and limitations of the 1-D profile reconstructions, the simulation analysis was also conducted. n simulation analysis, when the plumes are distributed broadly, and not congregated near the origin of the whole dispersion plume, RECON3bm, a PIC processing method which proceeded with the original generated PIC without the information of PIC1, provided the better results than other processing methods. Due to the flexibility of the lower limit in normal basis function, when the beginning of the testing plume is not at the origin, applying a normal basis function can provide better results than the others. In the field study, the first localization approach can successfully localize both of N2O and SF6. The smallest distances between real source locations were 4.3 meters for N2O and 3.7 meters for SF6. The second approach can provide the preliminary but significant indications of tracing back the emission sources. The distances from this approach were 7.7 meters for N2O and SF6. These two localization approaches can provide good estimations of source locations. The real source locations were properly covered by the estimated area whose standardized frequencies are higher than 50%.
Subjects
source localization
air pollutant
emission sources
OP-FTIR
optimization algorithm
Monte Carlo
Type
thesis
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