Measurement of Soot Volume Fraction and Temperature for Oxygen-Enriched Ethylene Combustion Based on Flame Image Processing

Abstract

Abstract:A method for simultaneously visualizing the two-dimensional distributions of temperature and soot volume fraction in an ethylene flame was presented. A single-color charge-coupled device (CCD) camera was used to capture the flame image in the visible spectrum considering the broad-response spectrum of the R and G bands of the camera. The directional emissive power of the R and G bands were calibrated and used for measurement. Slightly increased temperatures and reduced soot concentration were predicted in the central flame without self-absorption effects considered, an iterative algorithm was used for eliminating the effect of self-absorption. Nine different cases were presented in the experiment to demonstrate the effects of fuel mass flow rate and oxygen concentration on temperature and soot concentration in three different atmospheres. For ethylene combustion in pure-air atmosphere, as the fuel mass flow rate increased, the maximum temperature slightly decreased, and the maximum soot volume fraction slightly increased. For oxygen fractions of 30%, 40%, and 50% combustion in O 2 /N 2 oxygen-enhanced atmospheres, the maximum flame temperatures were 2276, 2451, and 2678 K, whereas combustion in O 2 /CO 2 atmospheres were 1916, 2322, and 2535 K. The maximum soot volume fractions were 4.5, 7.0, and 9.5 ppm in oxygen-enriched O 2 /N 2 atmosphere and 13.6, 15.3, and 14.8 ppm in oxygen-enriched O 2 /CO 2 atmosphere. Compared with the O 2 /CO 2 atmosphere, combustion in the oxygen-enriched O 2 /N 2 atmosphere produced higher flame temperature and larger soot volume fraction. Preliminary results indicated that this technique is reliable and can be used for combustion diagnosis.

Spectrometer-Based Line-of-Sight Temperature Measurements during Alkali-Pulverized Coal Combustion in a Power Station Boiler

“…Thus, there are additional equations for the radiation intensity, KL, and T, so that the number of equations is greater than the number of unknown parameters. To solve the equations, a nonlinear least squares method is applied for calculating KL and T. The value of KL, which is independent of the wavelength, can then be used in Equation (4) to determine the spectrally dependent ε λ .…”

“…To solve the equations, a nonlinear least squares method is applied for calculating KL and T. The value of KL, which is independent of the wavelength, can then be used in Equation (4) to determine the spectrally dependent λ ε .…”

“…Various methods for flame detection and diagnosis have been reported [1][2][3][4][5]. The laser spectroscopy method [6] has high temporal and spatial resolution, and can be used to measure temperature and to determine the concentrations of many components during the combustion process.…”

“…The diameter of individual soot particles is about 20-40 nm, and coal, char, and ash particles are about 2-500 µm [25]. Therefore, soot particles are significantly smaller than the accompanying coal and char particles and can be optically isolated [4]. However, the soot cloud generated by the decomposition of volatile substances in a high-temperature environment produces a semi-transparent media with an associated Energies 2017, 10, 1375 3 of 14 equivalent.…”

On the Response of Nascent Soot Nanostructure and Oxidative Reactivity to Photoflash Exposure

“…Soot emission to the environment reduces air quality, affects the climate and can cause health problems such as asthma, lung cancer, and cardiovascular disease [1,2]. For this reason , soot formation in combustion has been widely investigated in diesel engine [3][4][5] and different flame structures [6,7] over the years. Therefore, the reduction of soot emission is a great challenge and it is of great importance to understand the soot formation process and characteristics at different operating conditions.…”