Flame pyrometry

Variations of flame temperatures with exhaust-gas recirculation. Flame temperature maps are obtained by processing images obtained from a combustion chamber of a heavy-duty diesel engine using two-color pyrometry. Images are taken at 2° after the TDC at 1200rpm low-load condition. 

The use of the infrared pyrometric method extended significantly the range of measurement. Infrared pyrometry has the advantage of being equally adaptable to luminous low-transparency and to nonluminous flames. 

Fig. 8 Representative thermal image of the BST flame as measured by pyrometry.

Hernberg, R., Stenberg, J., and Zethraeus, B. "Simultaneous In Situ Measurement of Temperature and Size of Burning Ghar Particles in a Fluidized Bed Furnace by Means of Fiberoptic Pyrometry." Combustion and Flame 95, nos. 1-2 (1993) 191-205. 

Pyrometry is thought to be the most feasible method to extract quantitative information from radiation spontaneously emitted from flames. Temperature distributions over large regions of the flame can be derived by applying the Plank law to every pixel of a CCD sensor. Two-color techniques are usually applied, due to its reduced sensitivity to uncertainties in emissivity or attenuation. Infrared cameras are used in most cases, as radiation levels are highest in this region of the spectrum [4-7]. Two channels of RGB video cameras have been also used in some works [8] although less accurate, this has the... 

The flame maps obtained from pyrometry or chemiluminescence imaging can provide a most valuable insight into the characteristics of the combustion process. However, it should be noted that those data are rarely meaningful by themselves and their physical interpretation or their use for monitoring or optimization purposes require the participation of experienced researchers or operators as well as some prior knowledge on the values (e.g., peak temperatures) or patterns associated to different combustion regimes and/or to optimal operation. 

The two-color method was applied to estimate two-dimensional (2D) contour of temperature and KL factor (KL factor is the factor used to indicate soot) distribution in the combustion flame. This two-color pyrometry system was set up by placing Vari lens that has the two different band-pass filters 488 nm in center wavelength (FWHM 11.3 nm) and 634 nm in center wavelength (FWHM 8.5 nm) for separating images to be two in front of an ICCD camera lens. The intensity data of both filters were used to calculate the tme temperature and KL factor. 

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