$\mathrm{CO}_{2}^{*}$ chemiluminescence study at low and elevated pressures

Abstract

Chemiluminescence experiments have been performed to assess the state of current CO * 2 kinetics modeling. The difficulty with modeling CO * 2 lies in its broad emission spectrum, making it a challenge to isolate it from background emission of species such as CH * and CH 2 O * . Experiments were performed in a mixture of 0.0005H 2 + 0.01N 2 O + 0.03CO + 0.9595Ar in an attempt to isolate CO * 2 emission. Temperatures ranged from 1654 K to 2221 K at two average pressures, 1.4 and 10.4 atm. The unique time histories of the various chemiluminescence species in the unconventional mixture employed at these conditions allow for easy identification of the CO * 2 concentration. Two different wavelengths to capture CO * 2 were used; one optical filter was centered at 415 nm and the other at 458 nm. The use of these two different wavelengths was done to verify that broadband CO * 2 was in fact being captured, and not emission from other species such as CH * and CH 2 O * . As a baseline for time history and peak magnitude comparison, OH * emission was captured at 307 nm simultaneously with the two CO * 2 filters. The results from the two CO * 2 filters were consistent with each other, implying that indeed the same species (i.e., CO * 2 ) was being measured at both wavelengths. A first-generation kinetics model for CO * 2 and CH 2 O * was developed, since no comprehensively validated one exists to date. CH 2 O * and CH * were ruled out as being present in the experiments at any measurable level, based on calculations and comparisons with the data. Agreement with

Chemiluminescence as diagnostic tool in the development of gas turbines

“…Naturally most fundamental studies on chemiluminescence have been undertaken under slightly idealised conditions at either atmospheric premixed or even laminar flames with standardised fuels and their validity under more realistic conditions has only recently received more attention [2,17,30]. From these standardised cases it can be deduced that in general the brighter flames have the hottest temperatures and also produce most NO x .…”

“…The pressure coefficient γ was given by Higgins [27,28] to be −0.86 for OH * and −0.64 for CH * . The non-integer polynomial fit has been chosen for historical reasons, although most likely a more exponential or Arrhenius type behaviour is to be expected since the excited species are formed by chemical reactions following Arrhenius type reaction rates [30]. For the current approach, however, only the difference in slope in a relatively small range of different species is relevant.…”

“…Furthermore, the chemiluminescence reveals details about the nature of the flame chemistry and physics. The importance of chemiluminescence research from idealised kinetic experiments to large scale applied detection does not only help to understand NO x formation, but it can also yield insight into the timescales of formation, which are probably closely linked to the kinetically description of ground state chemistry [30].…”

Experimental and Numerical Study of Chemiluminescence Characteristics in Premixed Counterflow Flames of Methane based Fuel blends

“…The 4,28 was included in the chemiluminescence sub-model. The reaction rate of R2 was updated, according to the recent shock-tube measurement from Bozkurt and Metehan 31 .…”

“…Similar, for CH(A) * chemiluminescence, three steps reaction models have been widely researched. However, for C 2 * and CO 2 * reactions, limited information has reported the reaction rates of their formation reactions 4,28,29 . Although a lot of effort has gone into measuring the reaction rates of the excited species formation reactions, the reaction rates measured by different researchers are not in close agreement.…”