Atomic Absorption Flame Temperature Distribution Measured by Fiber Optics

Abstract

Atomic absorption flame temperature distributions have been investigated.The two-line method based on the fiber optics coupling light into the rapid-scanning spectrometer to measure temperature has been developed. Its feature is that a simpler apparatus used can obtain temperature distributions over the entire section of the flame in high resolution. The result shows some characteristics of premixed air-acetylene flame used for analytical spectrometry.

Measurement of Flame Temperature Using Simultaneous Dual- line Atomic Absorption of Two Elements

“…A possible explanation for this phenomenon could be that the unreacted acetylene will combust with the surrounding air, thus resulting in an increase in flame temperature. These flame temperatures were comparable to the values in the literature as the normally recorded temperature is about 2400 to 2600 K. 7,10,20 The flame temperature is mainly dependent on the type of flame, the gas flow rates, the burner design, the sampling method and the optics of measuring method. Therefore, the flame temperature measured and calculated by the proposed method is acceptable.…”

“…6 A premixed laminar air/acetylene flame is considered to follow the LTE conditions based on frequent collision of the particles in the flames, such as electrons, ions, atoms, molecules, and so on. 7,8 Therefore, the flame temperature can be deduced by dual-line atomic spectroscopy methods involving two different transitions with different excitation energies.…”

Spatially Resolved Temperature Determination of an Air/Acetylene Flame Using the Two-Step Laser-Enhanced Ionization Technique

“…33 With the use of AA coupled to ® ber-optics detection, Wang et al reported a lower temperature of 1910± 2230 K at a height range of 5± 30 mm in an even more fuel-rich ¯ame, into which the ¯ow rates of air and acetylene were 6.7 and 1.7 L/min. 37 The latter discrepancy may arise from the presence of more carbon-containing radicals; incomplete reaction may lower the resulting temperature. In contrast, the previous LEI measurement exhibited a slightly higher temperature of 2504± 2521 K in a fuel-leaner ¯ame, composed of an air/fuel ratio of 12.5:0.5 at 7.5 mm from the burner top.…”

“…26 The lower temperature in the edge found by Fernandez and Bastiaans was in a cylindrical ¯ame, 38 and that detected by Wang et al was in a slot burner. 37 The entrainment of external air renders the ¯ame subject to change in local stoichiometry, which decreases the temperature. The precision of temperature evaluated in the edge appears to be poor relative to the central portion, since ¯ame instability reduces the signal-to-noise ratio.…”

“…40 In contrast, Wang et al showed an opposite tendency in a very fuel-rich ¯ame. 37 RID versus LEI. In contrast to our excitation temperature measurement, Winefordner and co-workers recently determined a spatially resolved OH rotational temperature using indium-based resonance ionization detection (RID).…”