Experimental Study of Oxygen Enrichment Effects on Turbulent Non

Article pubs.acs.org/EF

Experimental Study of Oxygen Enrichment Effects on Turbulent Nonpremixed Swirling Flames Nazim Merlo,† Toufik Boushaki,*,†,‡ Christian Chauveau,† Stéphanie de Persis,†,§ Laure Pillier,† Brahim Sarh,†,‡ and Iskender Gökalp† †

Institut de Combustion Aérothermique Réactivité et Environnement (ICARE), Centre National de la Recherche Scientifique (CNRS), 1C Avenue de la Recherche Scientifique, 45071 Orléans Cedex 2, France ‡ Génie Thermique et Énergie (GTE), Institut Universitaire de Technologie d’Orléans (IUT), and §Faculté des Sciences, Université d’Orléans, 45067 Orléans Cedex 2, France ABSTRACT: The current paper describes the effects of oxygen enrichment on flame stability and pollutant emissions for turbulent non-premixed swirling flames. The study is motivated by CO2 capture applications further to the increase of the CO2 concentration by the O2 addition. The burner configuration consists of two concentric tubes with a swirl placed in the annular part for air or oxygen−air. The exhaust gas compositions are measured using gas analyzers. OH chemiluminescence experiments are conducted to investigate the stability of flames. The measurements were performed for oxygen concentrations ranging from 21 to 30% by volume, with swirl numbers of 0.8 and 1.4 and global equivalence ratios of 0.8, 0.9 and 1. Results show that oxygen enrichment enhances combustion efficiency and flame stability. The increase of the oxygen concentration in air leads to a decrease of lift-off heights and fluctuations of the flame base. Increasing the swirl number significantly improves the flame stability. Experiments demonstrated that the CO2 emissions linearly increase with an increasing O2 content in the oxidant. The CO emissions are shown to decay exponentially, whereas the NOx emissions, mainly produced through the thermal pathway, increased exponentially with oxygen addition. temperature constant around 1220 °C. Zhou et al.11 and Song et al.12 reported that oxygen enrichment significantly enhances the thermal NOx formation. To reduce NOx formation, staged combustion is used to control the mixing of fuel and air. Cozzi and Coghe13 studied a burner configuration similar to the present work configuration and examined the influence of air staging on NOx formation. They compared an axial and a radial fuel injection into the secondary air. They concluded that a radial injection allows for a faster centrifugal mixing. In the air case, Cheng et al.14 observed that increasing the level of premixing decreases the flame length in the case of partially premixed swirling flames. They also noticed a minimum of NOx and CO emissions for given optimum conditions of premixing in swirling flames. Zhen et al. 15 recently studied the characteristics of oxygen-enriched inverse diffusion swirling flames. They investigated the changes in flame appearance, flame temperature, overall pollutant emission, and flame impingement heating rate on a liquefied petroleum gas (LPG) flame. This work presents an experimental study of methane− combustion in air and oxygen-enriched air for turbulent nonpremixed swirling flames. The application of this study concerns furnaces and industrial boilers. After a description of the experimental setup and measurement techniques, the influence of oxygen enrichment, the swirl intensity, and the equivalence ratio on oxygen-enriched flame characteristics are analyzed.

1. INTRODUCTION Fossil fuels will remain dominant, accounting for roughly 80% of the primary energy production, in the global energy mix for the next 2 decades.1 The International Energy Agency (IEA)2 claimed that no more than one-third of proven reserves of fossil fuels can be consumed prior to 2050 to reach the goal of holding global warming to 2 °C. Numerous carbon capture and sequestration (CCS) strategies and technologies should be widely deployed to reduce the greenhouse gases, namely, CO2. Basically, three major CO2 capture concepts can be identified: post-combustion capture, oxy-combustion process, and precombustion decarbonization processes.3−6 Realistic oxy-combustion systems integrated to industrial power plants, such as natural gas combined-cycle (NGCC) plants, where high oxygen content flow is required, impose a total thermal efficiency penalty up to 10 points mainly because of oxygen production.7 Oxygen enrichment refers to oxygen concentrations ranging from 21 to 90%; over 90% of O2, it is the oxy-fuel combustion.8 One of these promising applications of oxygen-enriched combustion is to increase the CO2 concentration in burned gases and, subsequently, to improve the efficiency of CO2 capturing processes as reported by Favre et al.9 The authors assessed a simulated hybrid process combining an oxygen enrichment step and a CO2 capture step by membrane permeation. It is shown that the hybrid process can lead to a 35% decrease of the energy requirement compared to oxy-fuel combustion. Another important effect of oxygen enrichment is to increase the flame temperature, which is beneficial to enhance radiative heat transfer in flames. Wu et al.10 observed a decrease of 26% fuel consumption rate when oxygen enrichment varies from 21 to 30% while keeping the furnace © 2013 American Chemical Society

Received: May 6, 2013 Revised: August 23, 2013 Published: August 25, 2013 6191

dx.doi.org/10.1021/ef400843c | Energy Fuels 2013, 27, 6191−6197

Energy & Fuels

Article

Figure 1. Schematic view of the coaxial swirl burner.

The study is focused on flame stability through the lift-off heights and their fluctuations, as well as pollutant emissions, such as CO, CO2, and NOx.

2. EXPERIMENTAL SECTION The burner configuration consists of two concentric tubes with a swirler placed in an annular part for air or oxygen−air, as shown in Figure 1. The central tube delivers the methane through eight holes (diameter Ø = 3 mm) symmetrically distributed on the periphery of the pipe, just below the burner exit plane. The radial injection of fuel is used to enhance mixing at the near field of the burner exit. The degree of swirl for rotating flows is usually characterized by the non-dimensional swirl number Sn. It increases while increasing the intensity of swirl. Sn represents the ratio of axial flux of tangential momentum Gθ and axial flux of axial momentum Gx as shown in eq 1

Sn =

Gθ Gx R

(1)

where R is an equivalent nozzle radius. In this study, eight guide vanes were designed with various vane angles, which induce swirl degree variations. The “geometrical” swirl number Sn related to this configuration yields (eq 2)16

Sn =

4 1 ⎛⎜ 1 ⎞⎟ 1 − (R h /R ) tan α0 ⎝ ⎠ 1 − ψ 2 1 − (R h /R )2

Figure 2. Combustion chamber. the air, the oxygen, and the fuel are regulated by the thermal mass flow controllers (Brooks SLA5851S). The measurements are performed for oxygen concentrations ranging from 21 to 30% in volume, with swirl numbers of 0.8 and 1.4 and global equivalence ratios of 0.8, 0.9 and 1. Table 2 summarizes volumetric flow rates of the reactants as a function of the oxygen enrichment for equivalence ratios (Φ) = 0.8, 0.9, and 1. Note that the oxidizer flow rate is kept constant with oxygen enrichment for a given global equivalence ratio, whereas the fuel flow rate increases. Concentrations of exhaust gases, such as NOx, CO, CO2 and O2, are measured by a HORIBA PG250 multigas analyzer. NOx (NO + NO2) is detected by a chemiluminescence technique; CO and CO2 are detected by non-dispersive infrared detectors; and O2 is detected by a paramagnetic detector. Combustion products are sampled by a PSP4000-HCT sampling probe and transported with a heated line transfer to prevent condensation of water vapor. The sampling probe is located at 1 m above the burner, which is centered in the combustion chamber. Before operating gas measurements, a chiller (Presampler PSS5) removes water vapor contained in the combustion gases; thus, the measurements obtained are on dry exhaust gases. The uncertainties in the measurements of pollutant emissions are around to 1% of the measured concentration. The OH* chemiluminescence technique is used to visualize the reaction zone and, therefore, to measure the lift-off heights and flame lengths.17,18 The flame images have been obtained by collecting the instantaneous OH* at 306.4 nm on a Princeton Instrument intensified charge-coupled device (CCD) camera (PI-MAX Gen II), with a 105 mm UV Nikkor lens ( f/4.5). The camera is operated in a 1024 × 1024

(2)

where ψ is the blockage factor, Rh is the swirl internal radius, R is the swirl external radius, and α0 is the vane angle. Values of these geometric parameters are summarized in Table 1 for the two swirl numbers Sn = 0.8 and 1.4. The swirler is located at HSn = 61 mm below the burner exit plane.

Table 1. Geometric Data of the Swirl Generator (See eq 2) Sn = 0.8 Sn = 1.4

R (mm)

Rh (mm)

α0 (deg)

ψ

17.5 17.5

8.8 8.8

47 60

0.17 0.23

The experiments are conducted using a 25 kW cylindrical combustion chamber of 1.2 m in height and 0.3 m in diameter, cooled by water circulation (Figure 2). There are eight visualization windows allowing optical measurements. A global equivalence ratio (Φ) can be defined as the molar ratio of methane and oxidant at the injection to the molar ratio of methane and oxidant required for stoichiometric burning as

Φ=

2VCH4,fuel VO2,oxidant

(3)

where V is the volumetric flow rate. An oxygen−air mixture is employed as the oxygen-enriched oxidizer flow. The mass flow rate of 6192


Energy & Fuels

Article

Table 2. Operating Conditions for Equivalence Ratios (Φ) = 0.8, 0.9, and 1 as a Function of the Oxygen Content of 21, 25, and 30% volumetric flow rates (NL/min) Φ = 0.8

Φ = 0.9

Φ=1

oxygen volume fraction (%)

CH4

O2

air

CH4

O2

air

CH4

O2

air

21 25 30

20.4 24.3 29.1

0 12 28

243 231 215

22.9 27.3 32.7

0 12 28

243 231 215

25.5 30.3 36.4

0 12 28

243 231 215

pixel matrix with a 16 bit output digitization. The integration time of the camera for chemiluminescence images is fixed at 40 ms. The OH* emission band has been filtered with a 306BP20 band-pass filter (Omega Optical), which is centered at 306 nm with a 20 nm bandwidth. To obtain relevant statistical distributions, up to 400 instantaneous OH* images are collected for each operating condition. To determine the lift-off heights and the flame lengths, an image processing is used for all of the images. A histogram-based thresholding with filtering analysis is developed with Matlab and applied to detect the flame contours and the flame base fluctuations. The real measurement field is 80 mm along the radial and axial directions with a spatial resolution of 12 pixels/mm. Table 3 shows the uncertainty assessment in the lift-off height and flame height measurements. The threshold value enables detection

Table 3. Uncertainties Assessment of Lift-off Height and Flame Length Measurements source of uncertainty

estimated range (%)

factor of conversion (mm/pixel) threshold value burner position total uncertainty

±0.8 ±3.5 ±1 ±3.6

Figure 3. Variation of EICO versus O2 addition, for equivalence ratios (Φ) of 0.8, 0.9, and 1 and swirl numbers (Sn) of 0.8 and 1.4.

where the flame front begins and where the flame ends. Its determination is quite a delicate problem depending upon the method employed. The method based on the inflection point detection of the chemiluminescence intensity profiles along the vertical axis is employed in this study. Considering any experimental case, the threshold value corresponds to the chemiluminescence intensity of the mean image at the inflection point. Then, this threshold value is applied to all instantaneous images to determine the instantaneous liftoff heights and flame heights. Assuming that the sources of uncertainties are independent, the total uncertainty, mentioned in the last line of Table 3, is less than 4% in all cases. Nevertheless, it is observed that these uncertainties are hidden by the fluctuations of the lift-off heights and flame lengths. That is why the vertical bars correspond to the standard deviation based on all measured lift-off heights and all measured flame lengths. In the Results and Discussion section, the error bars represent the standard deviation based on 400 measured lift-off heights and 400 measured flame lengths. In all experimental cases, it is observed that the standard deviation ranged from 5 to 55% and depends upon the oxygen enrichment cases.

Figure 4. CO2 emissions versus O2 addition for equivalence ratios (Φ) of 0.8, 0.9, and 1 and swirl numbers (Sn) of 0.8 and 1.4.

EICO (g/kg) =

3. RESULTS AND DISCUSSION 3.1. Pollutant Emissions. Exhaust gas combustion products, such as CO2, CO, and NOx, are studied with various oxygen enrichment and other parameters, such as the global equivalence ratio and the swirl number. CO emissions are plotted in Figure 3 against the oxygen volume fraction in the oxidizer for three equivalence ratios of 0.8, 0.9, and 1 and two swirl numbers of 0.8 and 1.4. CO measurements are given by emission index (EICO as gCO/kgfuel unit), which is calculated using concentration measurements of CO, CO2, and CH4 in the flue gas as19

1[CO]MWCO1000 ([CO2 ] + [CO] + [CH4])MWCH4

(4)

where MW refers to molecular weight, brackets refer to molar fraction, and factor 1 accounts for the formation of 1 mol of CO2 from 1 mol of CH4. Results are presented at 3% dry O2 in the flue gas, a percentage usually used for combustion plants and, in particular, for industrial furnaces. The EICO data decrease exponentially with oxygen enrichment. The EICO data also decrease when the global equivalence ratio increases from 0.8 to 1. In the case of a swirl number of 1.4, the EICO data are slightly lower than in the case of a swirl number of 0.8. Oxygen enrichment enhances CO conversion to CO2. 6193


Energy & Fuels

Article

Figure 8. Flame stability map as a function of flow rates of CH4 and air for equivalence ratios (Φ) from 0 to 1.4 with Sn = 0.8. Figure 5. CE evolutions with O2 addition for equivalence ratios (Φ) of 0.8 and 0.9 and swirl numbers (Sn) of 0.8 and 1.4.

Figure 9. Flame stability map as a function of flow rates of CH4 and air for equivalence ratios (Φ) from 0 to 1.4 with Sn = 1.4.

the CO conversion to CO2 cannot be completed. Swirl intensity might tend to improve the mixing and to increase the residence time inside the reaction zone, promoting the CO conversion to CO2. Combustion efficiency, CE, is defined as

Figure 6. Variation of EINOx versus O2 addition for equivalence ratios (Φ) of 0.8, 0.9, and 1 and swirl numbers (Sn) of 0.8 and 1.4.

CE = [CO2 ]/([CO2 ] + [CO]) × 100

(5)

Oxygen enrichment enhances combustion efficiency because CE increases from 96 to 100% when oxygen enrichment increases from 21 to 30%, as shown in Figure 5. CO2 emissions are plotted in Figure 4 against the oxygen volume fraction in the oxidizer for three equivalence ratios of 0.8, 0.9, and 1 and two swirl numbers of 0.8 and 1.4. CO2 emissions increase linearly with oxygen enrichment. For a global equivalence ratio of 0.8, CO2 increases by a factor of 1.5 between 21 and 30% of oxygen content. Increasing the global equivalence ratio tends to promote the CO2 formation. These linear CO2 evolutions can be explained by considering complete methane combustion in air and oxygen-enriched air as [CO2 ]complete = Φ[O2 ]/(2 − Φ[O2 ])

(6)

where [O2] is the fraction of oxygen in the oxidizer stream and Φ is the equivalence ratio. CO2 predictions are always slightly greater than the measurements because the CO conversion to CO2 is not completed (Figure 3). The EINOx emissions with oxygen volume fraction are shown in Figure 6 for three equivalence ratios of 0.8, 0.9, and 1 and two swirl numbers of 0.8 and 1.4. NOx measurements are given by emission index (EINOx as gNOx/kgfuel unit), which is

Figure 7. Adiabatic flame temperature as a function of O2 enrichment for equivalence ratios (Φ) of 0.8, 0.9, and 1. Calculations are performed using EQUIL from CHEMKIN with the GRI-Mech 3.0 mechanism.

CO/CO2 equilibrium is obtained in high-temperature regions, but CO might be rapidly convected out of these regions, so that 6194


Energy & Fuels

Article

Figure 10. Chemiluminescence flame imaging for three oxygen enrichment cases: 21, 25, and 30% in volume, in the case of Φ = 0.8 and Sn = 0.8.

0.9, and 1. These calculations are performed by using EQUIL from CHEMKIN with the GRI-Mech 3.0 mechanism. For the three global equivalence ratios, the adiabatic flame temperature increases when oxygen enrichment increases. For a fixed oxygen fraction, the flame temperature increases with equivalence ratios from 0.8 to 1. The EINOx data decrease by a factor of 2.4 when the global equivalence ratio increases from 0.8 to 1 with 30% of oxygen content and a swirl number Sn of 0.8. These results can be explained by two reasons. First, when the equivalence ratio increases, the mole fraction of CO2 in combustion products increases. This increase of CO2 emissions induces an increase in the amount of recirculated CO2, which chemically increases the nitrogen oxide destruc-

calculated using concentration measurements of NOx, CO, CO2, and CH4 as EINOx (g/kg) =

1[NOx ]MWNO21000 ([CO2 ] + [CO] + [CH4])MWCH4 (7)

The EINOx data largely increase when the oxygen enrichment increases. Indeed, when oxygen enrichment increases from 21 to 30%, the EINOx data increase from 0.3 to 3.6 g/kg of CH4 with a global equivalence ratio of 0.8 and a swirl number of 0.8. This increase is due a priori to the increase of the flame temperature via thermal NO. Figure 7 shows the flame temperature with the O2 fraction for equivalence ratios of 0.8, 6195


Energy & Fuels

Article

blowout is very narrow. The map is divided into four parts: (1) stable lifted flame, (2) attached flame (the base of the flame is attached to the burner), (3) unstable lifted flame (lifted flame with high fluctuations of the base), and (4) blowout (obtained for a very low equivalence ratio with a very low flow rate of fuel and a high equivalence ratio with a high flow rate of fuel). With O2 enrichment, the domain of blowout a priori decreases. The present results concern the stable lifted flame area. Figure 10 shows examples of instantaneous images of OH chemiluminescence with a global equivalence ratio of 0.8 and a swirl number of 0.8 for three oxygen enrichments: 21, 25, and 30% in volume. Mean images are shown in the bottom of Figure 10. Asymmetrical flame structures are observed on average and instantaneous images, which show that flames are not axisymmetric. For lifted flames, namely, with oxygen enrichment from 21 to 25 vol %, and non-lifted flames (>27% O2), flame mean images are typically depicted with at least two more intense lobes, resulting in OH chemiluminescence signal integration along the line of sight. The flame base becomes closer to the burner when oxygen enrichment increases. Oxygen enrichment extends the stability limits of the burner, which is related to an extension of the flammability limits and an increase of flame velocity.25,26 Thus, oxygen-enriched flames can propagate (in premixing zones) and burn in regions where flow velocities are higher and where the mixing is not stoichiometric. 3.3. Lift-off Heights and Flame Lengths. Figures 11 and 12 show the evolutions of flame lift-off heights and flame lengths with oxygen enrichment for equivalence ratios of 0.8, 0.9, and 1 and two swirl numbers of 0.8 and 1.4. The bars in graphs represent the standard deviation of the variable. Uncertainties are estimated at 5 and 8% for mean flame height and mean flame length measurements, respectively. The lift-off height linearly decreases with oxygen enrichment. The lift-off height fluctuations also decrease with oxygen addition, which shows that oxygen addition improves the stability of the flame. In the air combustion case, the flame is lifted at roughly 40 mm above the burner exit plane for Φ = 0.8 and Sn = 1.4. The flame base fluctuates substantially at about ±10 mm. In the 30% oxygen-enriched combustion, the flame base is located only at 15 mm above the burner exit plane and fluctuations are within ±2 mm. Oxygen enrichment extends the flammability limits as mentioned previously. Increasing the swirl number tends to decrease the flame lift-off height. Thus, increasing the swirl number might enhance the stability of the flame. This behavior has also been reported in many previous studies.27−30 In addition, increasing the global equivalence ratio (Φ) results in a destabilization of flames because the flame lift-off height tends to increase for a swirl number of 1.4. The top of the flame is difficult to locate, and therefore, flame length measurements are difficult to perform in the case of swirling flames. Indeed, flames become wider while increasing the swirl number and obtain large fluctuations on its length even for high oxygen addition. The flame lengths decrease with oxygen addition in the case of Φ = 0.8. In the case of Φ = 0.9, the flame lengths seem to be roughly constant and are globally higher than in the case of Φ = 0.8 for a fixed oxygen enrichment.

Figure 11. Flame lift-off heights with O2 addition for equivalence ratios (Φ) of 0.8, 0.9, and 1 and swirl numbers (Sn) of 0.8 and 1.4.

Figure 12. Flame lengths with O2 addition for equivalence ratios (Φ) of 0.8 and 0.9 and swirl numbers (Sn) of 0.8 and 1.4.

tion.20 In diffusion flames with recirculating burned gases, prompt NO and thermal NO react with CO2 and decrease NOx emissions.21 The decrease of the CO2 amount in the recirculation zone led to higher NOx emissions. Second, for different equivalence ratios and different fractions of O2, the flame can attach to the burner and change its form. This behavior could modify mixing and disturb NOx formation. These tendencies were also found in the literature by Yon et al.22 Increasing the swirl number tends to reduce the EINOx production, in particular, for oxygen content superior to 27%. Assuming that NOx production is mainly described by the Zeldovich mechanism, the temperature of the NOx formation zone in flames decreases with increasing the swirl intensity. The experiments and computations23,24 demonstrated that NOx emissions decrease with increasing the swirl number, mainly because of the faster mixing with flue gases in the inner recirculation zone created by high swirling flows. 3.2. Stability Map and Chemiluminescence Flame Imaging. The configuration of the burner is complicated and original with eight transversal exits of fuel and a swirler for the oxidizer. First, the study of flame stability in the case of CH4− air is performed. Figures 8 and 9 show maps of flame stability for the two swirl numbers Sn = 0.8 and 1.4. The results show that the area of flame stability is very large and the area of

4. CONCLUSION This study deals with the characteristics of turbulent nonpremixed swirling flames with transverse injection of fuel. The 6196


Energy & Fuels

Article

(17) Dandy, D. S.; Vosen, S. R. Combust. Sci. Technol. 1992, 82 (1− 6), 131−150. (18) Bae, S. H.; Shin, H. D. Energy Fuels 2009, 23 (11), 5338−5348. (19) Turns, S. R.; Lovett, J. A. Combust. Sci. Technol. 1989, 66, 233. (20) Watanabe, H.; Marumo, T.; Okazaki, K. Energy Fuels 2012, 26, 938−951. (21) Park, J.; Park, J. S.; Kim, H. P.; Kim, J. S.; Kim, S. C.; Choi, J. G.; Cho, H. C.; Cho, K. W.; Park, H. S. Energy Fuels 2007, 21, 121−129. (22) Yon, S.; Sautet, J. C.; Boushaki, T. Energy Fuels 2012, 26, 4703− 4711. (23) Frassoldati, A.; Frigerio, S.; Colombo, E.; Inzoli, F.; Faravelli, T. Chem. Eng. Sci. 2005, 60 (11), 2851−2869. (24) Schmittel, P.; Günther, B.; Lenze, B.; Leuckel, W.; Bockhorn, H. Proc. Combust. Inst. 2000, 28 (1), 303−309. (25) Dyakov, I. V.; Konnov, A. A.; Ruyck, J. D.; Bosschaart, K. J.; Brock, E. C. M.; De Goey, L. P. H. Combust. Sci. Technol. 2001, 172 (1), 81−96. (26) Dirrenberger, P.; Le Gall, H.; Bounaceur, R.; Herbinet, O.; Glaude, P.-A.; Konnov, A.; Battin-Leclerc, F. Energy Fuels 2011, 25 (9), 3875−3884. (27) Boushaki, T.; Sautet, J.-C.; Labegorre, B. Combust. Flame 2009, 156 (11), 2043−2055. (28) Feikema, D.; Chen, R.-H.; Driscoll, J. F. Combust. Flame 1990, 80 (2), 183−195. (29) Takahashi, F.; Schmoll, W. J. Symp. (Int.) Combust., [Proc.] 1991, 23 (1), 677−683. (30) Yuasa, S. Combust. Flame 1986, 66 (2), 181−192.

emphasis is to evaluate the oxygen enrichment effects on the stability of a methane−air flame and pollutant emissions, such as CO, CO2, and NOx. The effects of the global equivalence ratio and swirl intensity are also analyzed. The main results are summarized as follows: (1) Oxygen enrichment promotes large CO conversion into CO2; CO2 increases linearly with oxygen addition. (2) NOx increases largely with oxygen addition mainly because of the increase of the flame temperature. (3) Flame stability is enhanced with oxygen addition even for low oxygen enrichment. (4) Flame lift-off heights and its fluctuations largely decrease with oxygen addition. The flame lengths decrease with oxygen addition for Φ = 0.8. In the case of Φ = 0.9, the flame lengths seem to be roughly constant and are globally higher than in the case of Φ = 0.8 for a fixed oxygen enrichment.

■

AUTHOR INFORMATION

Corresponding Author

*Telephone: +33-0-2-38-25-50-70. Fax: +33-0-2-38-25-78-75. E-mail: toufi[email protected]. Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS This work has been supported by the Agence National de la Recherche (ANR), Project CO2 EnergiCapt (ANR-10-EESI0003).

■

REFERENCES

(1) European Commission. World Energy Technology Outlook 2050: WETO-H2; European Commission: Brussels, Belgium, 2006. (2) Organisation for Economic Co-operation and Development (OECD)/International Energy Agency (IEA). World Energy Outlook 2012; OECD/IEA: Paris, France, 2012. (3) Li, B.; Duan, Y.; Luebke, D.; Morreale, B. Appl. Energy 2013, 102, 1439−1447. (4) Mondal, M. K.; Balsora, H. K.; Varshney, P. Energy 2012, 46 (1), 431−441. (5) Habib, M. A.; Nemitallah, M.; Ben-Mansour, R. Energy Fuels 2012, 27 (1), 2−19. (6) Li, H.; Ditaranto, M.; Berstad, D. Energy 2011, 36 (2), 1124− 1133. (7) Dillon, D. J.; Panesar, R. S.; Wall, R. A.; Allam, R. J.; White, V.; Gibbins, J.; Haines, M. R. Oxy-combustion processes for CO2 capture from advanced supercritical PF and NGCC power plant. In Greenhouse Gas Control Technologies 7; Rubin, E. S., Keith, D. W., Gilboy, C. F., Wilson, M., Morris, T., Gale, J., Thambimuthu, K., Eds.; Elsevier Science, Ltd.: Oxford, U.K., 2005; pp 211−220. (8) Baukal, C. E. Oxygen-Enhanced Combustion; CRC Press, Inc.: Boca Raton, FL, 1998; p 384. (9) Favre, E.; Bounaceur, R.; Roizard, D. Sep. Purif. Technol. 2009, 68 (1), 30−36. (10) Wu, K.-K.; Chang, Y.-C.; Chen, C.-H.; Chen, Y.-D. Fuel 2010, 89 (9), 2455−2462. (11) Zhou, L. X.; Chen, X. L.; Zhang, J. Proc. Combust. Inst. 2002, 29 (2), 2235−2242. (12) Song, J.; Zello, V.; Boehman, A. L.; Waller, F. J. Energy Fuels 2004, 18 (5), 1282−1290. (13) Cozzi, F.; Coghe, A. Exp. Therm. Fluid Sci. 2012, 43, 32−39. (14) Cheng, T. S.; Chao, Y. C.; Wu, D. C.; Hsu, H. W.; Yuan, T. Combust. Flame 2001, 125 (1−2), 865−878. (15) Zhen, H. S.; Leung, C. W.; Cheung, C. S. Appl. Energy 2011, 88 (9), 2925−2933. (16) Beér, J. M.; Chigier, N. A. Combustion Aerodynamics; Applied Science Publishers, Ltd.: London, U.K., 1972; p 264. 6197


Experimental Study of Oxygen Enrichment Effects on Turbulent Non

Recommend Documents