European Directives are coming into force setting increasingly stringent Emission Limit Values (ELVs) for key air pollutants and regulating emissions from combustion processes. Accurate meas-urement of emissions to the atmosphere is vital to control and reduce air pollution. Optical methods offer promising tools to investigate the dynamic release of molecular species from combustion envi-ronments. The IMPRESS 2 project [1] goes beyond state of the art in measuring the emissions of critical pollutants (e.g. HCl) with lower ELVs.
Tunable diode laser absorption spectroscopy (TDLAS) [2-4] is frequently applied in combustion research and industry for sampling-free and in situ gas analysis [5], but its application is normally limited to uniform conditions along the line-of-sight (LOS). However, in many applications, for ex-ample, combustion diagnostic measurements, heterogeneities (e.g. temperature, gas matrix) along the LOS may occur. In those conditions, the effects of heterogeneities should be considered for spectral fitting and concentration quantification [6].
A direct TDLAS (dTDLAS) based HCl spectrometer [7] has been developed in PTB recently. Here, the key point of this presentation is a better understanding of the effects of spatial gas matrix heter-ogeneity on the absolute accuracy of this spectrometer. A simulation model will be used here to ana-lyze the effects of spatial heterogeneities on dTDLAS HCl concentration measurement.
This work was supported by IMPRESS2 within the EMPIR.