Determination of liquefied petroleum flame temperatures using emission spectroscopy

Abstract

A espectroscopia de emissão foi utilizada na determinação da temperatura de chamas pré-misturadas de GLP. Investigou-se a emissão natural de radicais CH * em três diferentes condições de queima: razão estequiométrica de combustível/oxidante, excesso de combustível (chama rica) e excesso de oxidante (chama pobre). O valor médio obtido para a temperatura rotacional de CH * foi de 2845 70 K nas condições utilizadas nos experimentos. Esse valor não variou significativamente com os demais tipos de chama e é compatível com os cálculos de temperatura adiabática dos sistemas estudados. Essa temperatura também é concordante com resultados obtidos por via indireta, utilizando-se o método de linha reversa de sódio, que consiste em uma técnica bem estabelecida e independente da emissão natural. Temperaturas vibracionais de ca. 4600 K foram calculadas, indicando que o tempo de vida do CH * não é suficiente para que o equilíbrio entre os modos rotacionais e vibracionais seja estabelecido.Emission spectroscopy was used in the temperature determination of LPG (liquefied petroleum gas) premixed flames. Natural emission of CH * radicals was investigated in flames under three different burning conditions: fuel/oxydizer stoichiometric ratio, fuel excess (rich flame), and oxidizer excess (lean flame). An average value of 2845 70 K was obtained for CH * rotational temperature in the set up used in the experiments. This value did not show significant change with the type of flame analyzed and it is compatible with the calculated adiabatic flame temperatures of the investigated systems. This temperature value also agrees with that determined by an indirect measurement, using the sodium line reversal method, which is independent from the radical natural emission and well established in literature. Vibrational temperatures of ca. 4600 K were calculated, indicating that the CH * lifetime is insufficient for the establishment of an equilibrium state between the rotational and vibrational modes.

A high-entropy B4(HfMo2TaTi)C and SiC ceramic composite

“…We correlate this with the formation of the silica protection layer from silicon carbide on the sample surface, as was reported previously for ceramic composites containing SiC. 46,47 The sample was exposed to a liquefied petroleum gas (LPG) torch, which has a flame temperature of 2000°C, 48 for 20 s. The XRD patterns of the HEC composite before and after the torch experiment (Fig. 5b) are normalized at 2θ = 27.1°.…”

The effect of lambda-doublet levels in ethanol flame temperature estimation

“…This behavior is quite different of our past results from GLP flames, where the CH * rotational temperatures were much closer to the flame temperatures. 6 One possible explanation for this is the presence of a kinetic effect in the CH * chemiluminescent mechanism in ethanol flames, i.e., the mechanistic path of this radical leads to an excited population that is not completely deactivated before spontaneous emission. To test this hypothesis, CH * LIF measurements will be carried out in ethanol flames.…”

“…On the other hand, natural emission, or chemiluminecence, of the species also can be used for temperature measurement of flame. [5][6][7] Natural emission spectrum of a species contains electronic, vibrational and rotational information, including temperature data. The latter can be determined using the Boltzmann's method, which is based on the measurement of the relative peak intensities of emission lines of the species spectra.…”

Calibration-free self-absorption model for measuring nitric oxide concentration in a pulsed corona discharge

“…Emission spectroscopy has been widely used as a nonintrusive solution for quantitative measurements. This technique determines temperature by fitting the experimental spectrum with the calculated spectrum or simply on the basis of the relative intensities of two groups of lines [1][2][3][4][5][6]. In 2003, Laux et al [2] obtained a peak centerline temperature of approximately 7500 K in air and nitrogen plasmas by comparing the absolute intensity emission spectra of local thermodynamic equilibrium air with that from SPECAIR simulation.…”

“…In 2003, Laux et al [2] obtained a peak centerline temperature of approximately 7500 K in air and nitrogen plasmas by comparing the absolute intensity emission spectra of local thermodynamic equilibrium air with that from SPECAIR simulation. In the study of Carinhana et al [6], CH emission spectroscopy was used for the temperature determination of liquefied petroleum gas premixed flames. The rotational and vibrational temperatures were measured at approximately 2845 and 4600 K, which are consistent with the results obtained through the sodium line reversal method.…”