Extinction Spectroscopy for Characterization of Particulate Matter Size and Concentration in Fugitiv...
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Extinction Spectroscopy for Characterization of Particulate Matter Size and Concentration in Fugitive Plumes. Dr. Ram Hashmonay ARCADIS 4915 Prospectus Dr., Suite F Durham, NC 27713. Method Description. OP-FTIR is an accepted method for gas measurements

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Extinction Spectroscopy for Characterization of Particulate Matter Size and Concentration in Fugitive Plumes

Dr. Ram Hashmonay

ARCADIS

4915 Prospectus Dr., Suite F

Durham, NC 27713


Method description
Method Description Matter Size and Concentration in Fugitive Plumes

  • OP-FTIR is an accepted method for gas measurements

  • Particulate matter (PM) presence reveals a unique baseline structure (see below)


Method description cont
Method Description (cont.) Matter Size and Concentration in Fugitive Plumes

  • Baseline structure can be predicted for a given size distribution and optical constants using Mie theory

  • We developed an inversion algorithm to retrieve the aerosol size distribution from extinction (scattering+absorption) measurements

  • Optical properties (constants) of specific PM may be determined using a bench-top FTIR spectrometer


Mie theory
Mie Theory Matter Size and Concentration in Fugitive Plumes

Size Parameter a

d - particle diameter

l - wavelength


Mie theory cont
Mie Theory (cont.) Matter Size and Concentration in Fugitive Plumes

Complex Refractive Index

m(l) = n(l)-ik(l)

n – scattering term (refraction and reflection)

k – absorption term


Mie theory cont1
Mie Theory (cont.) Matter Size and Concentration in Fugitive Plumes

Extinction Efficiency:

  • Extinction efficiency of water in different part of the FTIR spectrum


Extinction as Function of Wavelength Matter Size and Concentration in Fugitive Plumes

  • sei - extinction for the ithwavelength

  • Qeij- dimensionless extinction efficiencies

  • Nj- number density for the jth aerosol size

  • dj- is the aerosol jth size class (diameter)


Shower experiment
Shower Experiment Matter Size and Concentration in Fugitive Plumes

  • OP-FTIR beam through water condensation aerosol

  • Size distribution confirmed by aerosol probe

  • Known optical constants (see below)


Shower experiment results
Shower Experiment Results Matter Size and Concentration in Fugitive Plumes


Predicted Smoke Extinction Spectrum Matter Size and Concentration in Fugitive Plumes


Smoke PM Extinction Matter Size and Concentration in Fugitive Plumes


Water Condensation Aerosol Matter Size and Concentration in Fugitive Plumes


2.5 Matter Size and Concentration in Fugitive Plumesmm Mean Size; 2 mm SD Gaussian Fit


Sahara Dust Optical Constant Matter Size and Concentration in Fugitive Plumes


Louisville Landfill Set-Up Matter Size and Concentration in Fugitive Plumes

Landfill

Dirt Road

OP-FTIR Beam


Diesel PM Matter Size and Concentration in Fugitive Plumes


Predicted Diesel Spectrum Matter Size and Concentration in Fugitive Plumes


Diesel Extinction Spectrum Matter Size and Concentration in Fugitive Plumes

2.3 mm

3.9 mm

9 mm


Path-Integrated Lidar Matter Size and Concentration in Fugitive Plumes


Enhanced Range Lidar Matter Size and Concentration in Fugitive Plumes


Conclusions Matter Size and Concentration in Fugitive Plumes

  • The first open-path optical technique to obtain real-time fugitive dust measurement and sizing

  • Measurement of liquid aerosol like water or pesticide drift

  • OP-FTIR can be used in field to gather multiple gases and PM emission data simultaneously

  • Extending the spectral range to the UV/VIS range will allow sizing of submicron PM


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