Comparative Analysis of Flame Image Features for Combustion Analysis

Background/ Objective: This article identifies the best feature of the flame video, captured with a camera with frequency response in visible spectrum, from which the flame temperature can be estimated. Methods/Statistical analysis: The flame videos at different air and fuel inlets with different boiler temperatures were recorded from a diesel fired boiler prototype. In the video frames, the flame region was localised by intensity based adaptive thresholding. The correlation between boiler temperature and measures of central tendency and dispersion of different colour channels of the video frames were investigated. Findings: Among the features of the flame video, Standard deviation of blue channel grey levels above 32.95, variance greater than 1293 and mean absolute deviation (MAD) above 30.38 could efficiently represent the region of optimum combustion air supply at which boiler temperature is maximum above 684 degree Celsius. Range of green channel grey levels, interquartile mean, variance and mean absolute deviation of blue channel grey levels are the video features exhibiting maximum correlation (ρ>-0.96) with boiler temperature. Applications/Improvements: The features of the flame video which are correlated with its temperature can be utilised to develop non-intrusive methods of temperature measurement. This will enable efficient control of combustion process.