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- Gunnarsson, Adrian, 1990, et al.
(författare)
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Radiative Heat Transfer Modeling and in Situ Diagnostics of Soot in an 80 kWth Propane Flame with Varying Feed-Gas Oxygen Concentration
- 2018
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 57:36, s. 12288-12295
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Tidskriftsartikel (refereegranskat)abstract
- This work presents experimental measurements of various 80 kWth propane flames, using a swirl burner, and modeling of the radiative heat transfer. The combustion conditions were altered by varying the oxygen concentration in the oxidant within range of 21-32%, while keeping the thermal input and oxygen-to-fuel ratio constant. Temperature, gas composition, and radiative intensity were measured using probes, while the soot volume fraction was quantified using nonintrusive laser-induced incandescence. The radiative intensity and the soot volume fraction increased with an increased oxygen concentration in the flame. When the oxygen concentration exceeded 27% the soot volume fraction was increased more than 14-fold. The results reveal the potential of promoting radiative heat transfer by increasing the oxygen concentration; the total radiative intensity becomes dominated by the soot particle contribution. In addition, laser-induced incandescence was successfully used for instantaneous and spatially resolved soot measurements in this type of furnace being at a technical scale.
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| 3. |
- Gunnarsson, Adrian, 1990, et al.
(författare)
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Soot Formation and Radiative Heat Transfer in Oxy-Fuel and Oxygen-Enhanced Propane Flames
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This work aims to determine radiation-related properties of various propane flames, where the measurements were conducted in a down-fired and cylindrical 100 kW furnace equipped with a swirl burner. The combustion conditions were varied by altering the composition of the oxidant. For six cases, oxygen-enhanced air was used, step-wise varying the oxygen concentration in the oxidant from 21% to 32%. Also for six cases, the furnace was operated in oxy-fuel mode, recirculating dry flue gas and varying the oxygen concentration from 25% to 42%. All measurements were conducted at an axial distance of 384 mm from the burner. Temperature, gas composition and radiative intensity were measured (by intrusive instruments) along the furnace diameter using probes while the soot volume fraction was quantified using non-intrusive laser induced incandescence (LII). An Nd:YAG laser at wavelength 1064 nm was used for the LII measurements, and a diode laser at wavelength 808 nm was used for extinction measurements for absolute calibration of the LII-signal. Two-dimensional images of the LII-signal were captured using an intensified CCD-camera and radial profiles of the soot volume fraction were achieved. The soot volume fraction increased with increasing oxygen concentration in the feed gas, and, when the oxygen concentration exceeded 30 and 42% for the oxygen-enriched air and oxy-fuel cases, respectively, the soot formation was substantially enhanced with volume fractions more than 10 times higher than for lower oxygen concentrations. The higher oxygen concentration required for the increased soot production in the oxy-fuel combustion cases is mainly due to the higher heat capacity of carbon dioxide that lowers the flame temperatures. The data collected from the measurements was used to model the radiative intensity using a discrete transfer model. In this model, gas properties are calculated using a statistical narrow-band model and particle properties are calculated using Rayleigh theory. Good agreement was achieved between the modeled and measured radiative intensity for most flames and the use of an LII-system to measure the soot volume fraction in this type of furnace was successful.
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| 4. |
- Simonsson, J., et al.
(författare)
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In-situ soot characterization of propane flames and influence of additives in a 100 kW oxy-fuel furnace using two-dimensional laser-induced incandescence
- 2019
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Ingår i: Proceedings of the Combustion Institute. - : Elsevier BV. - 1540-7489. ; 37:1, s. 833-840
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Tidskriftsartikel (refereegranskat)abstract
- In-situ soot characterization has been successfully performed in a 100 kW(th) down-fired oxy-fuel test furnace using laser-induced incandescence (LII) and extinction measurements. Primarily non-premixed propane flames were investigated in oxy-fuel mode with various concentrations of oxygen in the oxidant. The turbulent flame character was manifested through two-dimensional single-shot LII signals from soot showing strong spatial variations as well as local temporal variations. The LII signals were calibrated to soot volume fractions, f(v) , using in-situ extinction in the same spatial regions of the furnace. The results show increased f(v) for increasing oxygen concentration in the oxidant, which is related to increased temperatures as well as decreased mixing inside the furnace due to lowered total flow. For some measurement cases, the influence of additives was studied for flames in oxy-fuel and air environments. The results showed increased f(v) for additions of SO2 and NO for oxy-fuel conditions, while a decrease of f(v) was found for air-fed flames. Also, a large decrease in f(v) was found for water injection in the air-fed flames, and a slightly larger decrease for addition of KCl dissolved in water with the same amount of injected solution. Uncertainties in performing soot volume fraction measurements using LII and extinction in this large-scale furnace are discussed, and mainly considered to be uncertainties in E(m) for soot, the spatial variation of the laser fluence in the large imaged area, and the estimation of the absorption length during extinction calibration.
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