Quantitative detection and imaging of soot particles by laser induced incandescence

1997 ◽  
Author(s):  
K. McManus ◽  
M. Allen ◽  
W. Rawlins ◽  
K. McManus ◽  
M. Allen ◽  
...  
Keyword(s):  
Quantitative Detection ◽  
Soot Particles ◽  
Laser Induced Incandescence

Two-dimensional imaging of ignition and soot formation processes in a diesel flame

2005 ◽  
Vol 6 (1) ◽  
pp. 21-42 ◽  
Author(s):  
H Kosaka ◽  
T Aizawa ◽  
T Kamimoto
Keyword(s):  
Soot Formation ◽  
Diesel Spray ◽  
Oxidation Reactions ◽  
Soot Particles ◽  
Nozzle Orifice ◽  
Spray Flame ◽  
Soot Precursor ◽  
Planar Laser ◽  
Laser Induced Incandescence ◽  
Ambient Gas

The processes of ignition and formation of soot precursor and soot particles in a diesel spray flame achieved in a rapid compression machine (RCM) were imaged two-dimensionally using the laser sheet techniques. For the two-dimensional imaging of time and of location where ignition first occurs in a diesel spray, planar laser-induced fluorescence (PLIF) of formaldehyde was applied to a diesel spray in an RCM. Formaldehyde has been hypothesized to be one of the stable intermediate species marking the start of oxidation reactions in a transient spray under compression ignition conditions. In this study, the laser-induced fluorescence (LIF) images of the formaldehyde formed in a diesel fuel spray during the ignition process have been obtained by exciting formaldehyde with the third harmonic of a neodymium-doped yttrium aluminium garnet (Nd:YAG) laser. The LIF images of formaldehyde in a spray revealed that the time when the first fluorescence is detected is almost identical with the time when the total heat release due to low-temperature oxidation reactions equals the heat absorption by fuel vaporization in the spray. The formaldehyde level rose steadily until the high-temperature reaction phase of diesel spray ignition. At the start of this ‘hot-ignition’ phase, the formaldehyde concentration fell rapidly, thus signalling the end of the low-temperature ignition phase. Increases in the initial ambient gas temperatures advanced the hot-ignition starting time. The first hot ignition occurred in the periphery of spray head at initial ambient gas temperatures between 580 and 660 K. When the ambient gas temperature was increased to 790 K, the position of the first ignition moved to the central region of the spray head. For the investigation of soot formation processes in a diesel spray flame, simultaneous imaging of the soot precursor and soot particles in a transient spray flame in an RCM was conducted by PLIF and by planar laser-induced incandescence (PLII) techniques. The third harmonic (355 nm) and the fundamental (1064 nm) laser pulses from an Nd:YAG laser, between which a delay of 44 ns was imposed by 13.3 m of optical path difference, were used to excite LIF from the soot precursor and laser-induced incandescence (LII) from soot particles in the spray flame. The LIF and the LII were separately imaged by two image-intensified charge-coupled device cameras with identical detection wavelengths of 400 nm and bandwidths of 80 nm. The LIF from the soot precursor was mainly located in the central region of the spray flame between 40 and 55 mm (between 270 and 370 times the nozzle orifice diameter d°) from the nozzle orifice. The LII from soot particles was observed to surround the soot precursor LIF region and to extend downstream. The first appearance of the LIF from the soot precursor in the spray flame preceded the appearance of the LII from soot particles. The intensity of the LIF from the soot precursor reached its maximum immediately after rich premixed combustion. In contrast, the intensity of the LII from soot particles increased gradually and reached its maximum after the end of injection. Measured LIF spectra, of the soot precursor in the spray flame, were very broad with the peak between 430 and 460 nm.

Laser-Induced Incandescence and Smoke Point Measurements to Characterize the Sooting Propensity of Biodiesel Diffusion Flame

2010 ◽  
Author(s):  
Michael Tran ◽  
Trinh Pham
Keyword(s):  
Diffusion Flame ◽  
Combustion Zone ◽  
Soot Formation ◽  
Smoke Point ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Substantial Impact ◽  
Yag Laser ◽  
Soot Particles ◽  
Laser Induced Incandescence

Combustion of biodiesel is rapidly expanding around the world, mainly for its significant reduction of emissions such as soot particulates. The presence of carbonaceous soot emitted indicates a reduction in efficiency of practical combustion systems. In addition, sub-micron soot particles can have substantial impact on the environment and human health. Common emission studies of neat and blends of biodiesel and diesel fuels have been investigated using compression ignition engines and capturing soot particles in the post-combustion zone. However, soot particles produced in the primary combustion zone can greatly influence the products in the post-combustion zone. To study soot formation in the primary combustion zone, laser diagnostic is performed on a laminar diffusion wick lamp. In this paper, the sooting propensity of various blends of soybean biodiesel and Ultra Low Sulfur Diesel (ULSD) fuels are investigated using both a traditional ASTM D-1322 standard smoke lamp and modern Laser-Induced Incandescence (LII) technique. Laser excitation is achieved using a pulsed Nd: YAG laser operating at 532nm wavelength. Although ultraviolet and infrared spectra can be used, the choice of an Nd: YAG laser operating at the second harmonic wavelength is preferred because interference from excitation of polycyclic aromatic hydrocarbons (PAHs) and the C2 Swan band can be reduced. A fast-gate Intensified Charge Coupled Device (ICCD) camera and a 450nm narrow band-pass filter are used to detect the spatially resolved LII signal. The qualitative LII signal provides the soot profile of different volume mixtures of biodiesel and diesel diffusion flame. Many researches report show reduction in soot particles emitted in the exhaust when biodiesel is used as a blend in compression ignited engines. The contribution of this research is to investigate whether similar sooting characteristics can be seen in the primary combustion zone by making measurements in the proximity of the flame front. In general, the LII signals and smoke point measurements show a decrease in soot particles produced when blending ratios of 25% biodiesel – 75% diesel (by volume) are used. One limitation of using the ASTM standard wick lamp is flame instability at higher blending ratios due to the increases in carbon deposit on the wick, which reduces the fuel vaporization rate. Therefore, smoke point measurement for blending ratios above B25 is not accurate since the flame height is not stable; hence, future experiments rely on LII technique to characterize soot emission properties. In order to perform LII laser diagnostics using higher blending ratios, comparison between smoke point measurements and LII signals will be characterized in this report using lower blending ratios.

scholarly journals Simultaneous Quantitative Detection of HCN and C2H2 in Combustion Environment Using TDLAS

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 2033
Author(s):  
Wubin Weng ◽  
Marcus Aldén ◽  
Zhongshan Li
Keyword(s):  
Laminar Flame ◽  
Tunable Diode Laser ◽  
Quantitative Detection ◽  
Temperature Dependent ◽  
Soot Particles ◽  
Laser Absorption ◽  
Hot Gas ◽  
Diode Laser Absorption ◽  
Combustion Environment

Emission of nitrogen oxides (NOx) and soot particles during the combustion of biomass fuels and municipal solid waste is a major environmental issue. Hydrogen cyanide (HCN) and acetylene (C2H2) are important precursors of NOx and soot particles, respectively. In the current work, infrared tunable diode laser absorption spectroscopy (IR-TDLAS), as a non-intrusive in situ technique, was applied to quantitatively measure HCN and C2H2 in a combustion environment. The P(11e) line of the first overtone vibrational band v1 of HCN at 6484.78 cm−1 and the P(27e) line of the v1 + v3 combination band of C2H2 at 6484.03 cm−1 were selected. However, the infrared absorption of the ubiquitous water vapor in the combustion environment brings great uncertainty to the measurement. To obtain accurate temperature-dependent water spectra between 6483.8 and 6485.8 cm−1, a homogenous hot gas environment with controllable temperatures varying from 1100 to 1950 K provided by a laminar flame was employed to perform systematic IR-TDLAS measurements. By fitting the obtained water spectra, water interference to the HCN and C2H2 measurement was sufficiently mitigated and the concentrations of HCN and C2H2 were obtained. The technique was applied to simultaneously measure the temporally resolved release of HCN and C2H2 over burning nylon 66 strips in a hot oxidizing environment of 1790 K.

Measurement of Soot Particles by Two-Color Laser-Induced Incandescence Method Combined with Cavity Ring-Down Spectroscopy

2019 ◽  
Vol 46 (3) ◽  
pp. 0304002
Author(s):  
王孟 Wang Meng ◽  
张焰峰 Zhang Yanfeng ◽  
陈军 Chen Jun ◽  
杨荟楠 Yang Huinan ◽  
苏明旭 Su Mingxu ◽  
...  
Keyword(s):  
Cavity Ring Down Spectroscopy ◽  
Soot Particles ◽  
Laser Induced Incandescence ◽  
Cavity Ring Down

Probing the smallest soot particles in low-sooting premixed flames using laser-induced incandescence

2015 ◽  
Vol 35 (2) ◽  
pp. 1843-1850 ◽  
Author(s):  
Henrik Bladh ◽  
Nils-Erik Olofsson ◽  
Thomas Mouton ◽  
Johan Simonsson ◽  
Xavier Mercier ◽  
...  
Keyword(s):  
Premixed Flames ◽  
Soot Particles ◽  
Laser Induced Incandescence
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