Flame and Emission Characteristics of a Premixed Swirl-stabilised Burner

2014 ◽  
Vol 71 (2) ◽  
Author(s):  
Chen Wei Kew ◽  
Cheng Tung Chong ◽  
Ng Jo-Han ◽  
Boon Tuan Tee ◽  
Mohamad Nazri Mohd Jaafar
Keyword(s):  
Equivalence Ratio ◽  
Soot Formation ◽  
Atmospheric Condition ◽  
Emission Characteristics ◽  
Flow Rates ◽  
Lean Blowout ◽  
Unburned Hydrocarbons ◽  
Flame Shape ◽  
Flame Imaging ◽  
Swirl Flame

The flame and emission characteristics of a premixed gaseous flame swirl burner are investigated under various equivalence ratio. The swirl flame is established using propane/air mixture at atmospheric condition. Flame imaging was performed to compare the global flame shape and intensity over a range of equivalence ratios and flow rates. Fuel-rich flame shows increased intensity due to the presence of soot formation. The lean blowout test was performed to determine the operating limit of the burner. Emissions of the propane swirl flame were measured at the exit of the burner outlet. Results show that NOx emissions peak at stoichiometric condition, f =1 as compared to the lean- and rich-burning regions. Carbon monoxide (CO) and unburned hydrocarbons (UHC) emissions were found to be low (< 10 ppm) under premixed, continuous swirl burning conditions for the equivalence ratio range of f = 0.7-1.1.

Effect of Nitrogen Dilution on the Lean Blowout Limit and Emissions of Premixed Propane/Air Swirl Flame

2014 ◽  
Vol 71 (2) ◽  
Author(s):  
Cheng Tung Chong ◽  
Chen Wei Kew ◽  
Ng Jo-Han ◽  
Boon Tuan Tee ◽  
Mohamad Nazri Mohd Jaafar
Keyword(s):  
Digital Camera ◽  
Atmospheric Condition ◽  
Nitrogen Addition ◽  
Lean Blowout ◽  
Nitrogen Dilution ◽  
Flame Burner ◽  
Unburned Hydrocarbons ◽  
Flame Shape ◽  
Flame Imaging ◽  
Swirl Flame

The effects of nitrogen dilution on propane/air flame and emissions was investigated using a model gas turbine type swirl flame burner. The burner consists of a six-vane axial swirler and a combustor wall made from quartz tube. Nitrogen was diluted at 5%, 10% and 15% by volume of the total main air flow rate with propane/air mixture at the burner plenum prior to combustion at atmospheric condition. Direct flame imaging was performed using a digital camera to observe the flame shape, intensity and lean blowout phenomenon of premixed nitrogen-diluted propane/air flames. The result shows that nitrogen addition to propane/air flame reduces flame intensity and lean blowout limit, making the nitrogen-diluted flames more susceptible to blowout. Emissions results show that NOx reduce with the increase of nitrogen dilution rate, while the effect on carbon monoxides and unburned hydrocarbons are insignificant.

scholarly journals Emission Characteristics for Swirl Methane–Air Premixed Flames with Ammonia Addition

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 662
Author(s):  
Joanna Jójka ◽  
Rafał Ślefarski
Keyword(s):  
Equivalence Ratio ◽  
Combustion Process ◽  
Great Influence ◽  
Emission Characteristics ◽  
Firing Rates ◽  
Numerical Tests ◽  
Ammonia Addition ◽  
Swirl Flame ◽  
Reactor Network ◽  
No Emissions

This paper details the experimental and numerical analysis of a combustion process for atmospheric swirl burners using methane with added ammonia as fuel. The research was carried out for lean methane–air mixtures, which were doped with ammonia up to 5% and preheated up to 473 K. A flow with internal recirculation was induced by burners with different outflow angles from swirling blades, 30° and 50°, where tested equivalence ratio was 0.71. The NO and CO distribution profiles on specified axial positions of the combustor and the overall emission levels at the combustor outlet were measured and compared to a modelled outcome. The highest values of the NO emissions were collected for 5% NH3 and 50° (1950 ppmv), while a reduction to 1585 ppmv was observed at 30°. The doubling of the firing rates from 15 kW up to 30 kW did not have any great influence on the overall emissions. The emission trend lines were not proportional to the raising share of the ammonia in the fuel. 3D numerical tests and a kinetic study with a reactor network showed that the NO outlet concentration for swirl flame depended on the recirculation ratio, residence time, wall temperature, and the mechanism used. Those parameters need to be carefully defined in order to get highly accurate NO predictions—both for 3D simulations and simplified reactor-based models.

Ignition and Exhaust Emission Characteristics of Spray Combustion in a Pre-Chamber Type Vortex Combustor

1992 ◽  
Author(s):  
Youichirou Ohkubo ◽  
Yoshihiro Nomura ◽  
Yoshinori Idota ◽  
Yoshihisa Gunji
Keyword(s):  
Flow Pattern ◽  
Heat Loss ◽  
Radiative Heat ◽  
Soot Formation ◽  
Spray Combustion ◽  
Exhaust Emission ◽  
Emission Characteristics ◽  
Radiative Heat Loss ◽  
Flame Kernel ◽  
Lean Blowout

The lean ignition limit, the lean blowout limit and the exhaust emission characteristics of spray combustion have been investigated experimentally using a pre-chamber type vortex combustor developed for a 300KW large-bus gas turbine engine. It has been verified that these depend on the spray characteristics of the fuel injector and the air flow pattern or the distribution of air in the chamber. Ignition succeeds through three processes. The first step is the formation of a flame kernel near the sparking ignitor, the second step is the propagation of the flame kernel into a flame holding region, and the last step is the formation of a rotating flame in that region. The lean blowout limit of the rotating flame depends on the air flow pattern in the pre-chamber when the air temperature in the combustor inlet is under 470K, while a constant fuel-air ratio of less than 0.001 is maintained at 470K and above. With no or a little secondary air, the NOx emission index does not increase in proportion to the fuel-air ratio, because both the gas temperature and residence time decrease due to the radiative heat loss caused by soot formation and reduction of a recirculation region in the main-chamber. These phenomena were evaluated with 3 dimensional numerical simulations taking account of spray combustion, soot formation, the extended-Zeldovich thermal NO formation and radiative heat loss.

Investigation of Soot Formation in Fuel-Rich Premixed Propane/Air Microcombustion at Low Temperatures

2020 ◽  
Author(s):  
Abdul H. Khalid ◽  
Jiashen Tian ◽  
Brent B. Skabelund ◽  
Ryan J. Milcarek
Keyword(s):  
Equivalence Ratio ◽  
Flow Reactor ◽  
Soot Formation ◽  
Inert Gas ◽  
Flow Rates ◽  
Soot Precursor ◽  
Before And After ◽  
Micro Flow ◽  
Gas Dilution ◽  
Lower Temperature

Abstract The advantage of micro/meso combustion includes higher efficiency, improved heat and mass transfer, swift startup and shutdown when compared with regular combustion. This study aims to investigate the critical sooting equivalence ratio and soot precursor formation in a micro-flow reactor with a controlled temperature profile of diameter 2.3mm and their dependence on the temperature ranging from 800–1250 °C. The equivalence ratio is varied from 1–13 and flow rates of 10 and 100sccm were investigated. Also, nitrogen is used to study the effect of inert gas dilution. A gas chromatograph is used to study the exhaust gas composition. The reactor is analyzed visually for the traces of soot particles before and after combustion, each time the temperature and/or equivalence ratio is varied. From 750–950°C, no soot is indicted at all equivalence ratios even up to 100. The inert gas dilution helped in raising the critical sooting equivalence ratio as expected because of the lower temperature. The results indicated an opposite trend to what has been well understood for the pre-mixed sooting flames, i.e., decreasing temperature decreases soot formation. The capability of the reactor to examine the effects of temperature on the critical sooting equivalence ratio at different flow rates has been successfully demonstrated.

Experimental Investigation of Methane Lean Blowout Limit; Effects of Dilution, Mass Flow Rate and Inlet Temperature

2012 ◽  
Author(s):  
Parisa Sayad ◽  
Alessandro Schönborn ◽  
Denny Clerini ◽  
Jens Klingmann
Keyword(s):  
Mass Flow ◽  
Flow Rate ◽  
Total Mass ◽  
Equivalence Ratio ◽  
Stability Limit ◽  
Inlet Temperature ◽  
Swirl Number ◽  
Flow Rates ◽  
Lean Blowout ◽  
Mass Flow Rates

Lean blowout (LBO) is one of the major instability problems of premixed combustion. LBO equivalence ratio is a function of inlet temperature and pressure, mass flow or aerodynamic loading, and fuel composition. All these, except the last, vary during startup and with load. Developing gas turbine combustors capable of operating within wider range of fuel compositions requires extensive knowledge about instability limits of the combustor at different operating conditions. In this work an atmospheric variable swirl combustor was used to study the influence of inlet temperature, mass flow, swirl number and dilution on lean blowout of methane. The equivalence ratio at LBO was investigated for methane at 3 different inlet temperatures at various swirl numbers. The swirl number was varied by changing the ratio of axial and tangential flow through the combustor inlet, and was determined using Laser Doppler Anemometry. The experiments showed that increasing the swirl number reduced the lean blowout equivalence ratio for a given inlet temperature and that increasing the inlet temperature reduced the lean blowout equivalence ratio at a certain swirl number. In order to study the effect of inlet mass flow rate on lean stability limit, blowout experiments were conducted at 7 different mass flow rates. The measurements showed that the total mass flow has a non-monotonic effect on the lean blowout limit. At total mass flow rates below 200 SLPM increasing the total mass flow extended lean stability limit whereas at mass flow rates higher than 300 SLPM the trend was reversed. The effect of fuel dilution on the LBO limit was also investigated by adding different fractions of N2 and CO2 to the fuel mixture. The results were compared with those for pure methane at the same swirl number. Dilution with either diluent reduced the LBO limit of methane. However at the concentrations lower than 50% the effect of dilution on LBO equivalence ratio was relatively small and no significant difference was observed between N2 and CO2 dilution.

scholarly journals Wavelet analysis of flame blowout of a liquid-fueled swirl burner with quarls

2019 ◽  
Vol 67 (5) ◽  
pp. 394-403
Author(s):  
Viktor Józsa ◽  
Gergely Novotni
Keyword(s):  
Wavelet Transformation ◽  
Acoustic Noise ◽  
Operating Regime ◽  
Pollutant Emissions ◽  
Swirl Number ◽  
Axial Thrust ◽  
Lean Blowout ◽  
Swirl Combustion ◽  
Thrust Control ◽  
Flame Shape

Lean swirl combustion is the leading burner concept today, used in several steadyoperating applications to ensure awide operating range and low pollutant emissions. Approaching lean blowout is highly desired by design to achieve the lowest possible NOX emission. It was shown earlier that quarls could significantly extend the operating regime of liquid-fueled swirl burners. In the present study, the accompanying acoustic noise is evaluated by continuous wavelet transformation to show the effect of various quarl geometries on lean flame blowout. However, the desired flame shape of swirl burners is V, first, and a straight flame, and then a transitory regime can be observed before the developed V-shaped flame through increasing the swirl number. If the axial thrust is excessive, blowout might occur in earlier stages. Presently, the characteristic bands before blowout were analyzed and evaluated at various quarl geometries, swirl numbers, and atomizing pressures. The latter parameter also acts as an axial thrust control to adjust the swirl number. firstly, a straight flame, then a transitory regime can be observed before the developed V-shaped flame through increasing the swirl number. If the axial thrust is excessive, blowout might occur in earlier stages. Presently, the characteristic bands before blowout were analyzed and evaluated at various quarl geometries, swirl numbers, and atomizing pressures. The latter parameter also acts as an axial thrust control to adjust the swirl number.

Surface Treated PDMS by UV-Vis Light for Microfluidic Device

2008 ◽  
Vol 1139 ◽  
Author(s):  
Seisuke Kano ◽  
Sohei Matsumoto ◽  
Naoki Ichikawa
Keyword(s):  
Surface Treatment ◽  
Water Injection ◽  
Atmospheric Condition ◽  
Aluminum Foil ◽  
The Other ◽  
Wave Number ◽  
Treatment Technique ◽  
Hydrophobic Property ◽  
Flow Rates ◽  
Pdms Surface

AbstractHydrophobic property of PDMS surface was improved by the 400 W UV-Vis lamp light irradiation in the atmospheric condition for several ten minutes. As a result of this surface treatment, the surface became to hydrophilic character for one month long. This surface treatment technique applied to PDMS micro-fluidic device and verified valve-less switching. The UV-Vis light irradiated to PDMS micro fluidic pattern with partly covered by aluminum foil. Finally inlet and outlets were connected 0.5 mm diameter tubes. The syringe pumps injected the distilled water into the inlet of the PDMS micro channel at the flow rates of 0.5, 5.0, and 50 μl/min for the both width channel. As results of water injection water flowed only the UV-Vis treated channel at the flow rates of 0.5 and 5.0 μl/min. On the other hand, the water flowed for all channels at the flow rate of 50 μl/min. This result was observed from 5.0 μl/min flow again for both width devices which dried by air. These results were occurred by the difference of the flow conductance and wettability. The mechanism of this hyrophilicity of PDMS was reported to form Si-O in the surface by means of glassy surface. From the IR spectra, the Si-O-Si peak shifted to higher wave number for UV-Vis irradiated PDMS than the untreated PDMS comparing with the other IR peaks. This result showed that the Si-O-Si network bonding of PDMS changed to the O-Si-O bonding around the surface.

scholarly journals An analytical model based on the G-equation for the response of technically premixed flames to perturbations of equivalence ratio

2017 ◽  
Vol 10 (2) ◽  
pp. 103-110 ◽  
Author(s):  
Alp Albayrak ◽  
Wolfgang Polifke
Keyword(s):  
Impulse Response ◽  
Time Scale ◽  
Equivalence Ratio ◽  
Premixed Flames ◽  
Flame Speed ◽  
Flame Surface ◽  
Heat Of Reaction ◽  
Local Behavior ◽  
Model Based ◽  
Flame Shape

A model for the response of technically premixed flames to equivalence ratio perturbations is proposed. The formulation, which is an extension of an analytical flame tracking model based on the linearized G-equation, considers the flame impulse response to a local, impulsive, infinitesimal perturbation that is transported by convection from the flame base towards the flame surface. It is shown that the contributions of laminar flame speed and heat of reaction to the impulse response exhibit a local behavior, i.e. the flame responds at the moment when and at the location where the equivalence ratio perturbation reaches the flame surface. The time lag of this process is related to a convective time scale, which corresponds to the convective transport of fuel from the base of the flame to the flame surface. On the contrary, the flame surface area contribution exhibits a non-local behavior: albeit fluctuations of the flame shape are generated locally due to a distortion of the kinematic balance between flame speed and the flow velocity, the resulting wrinkles in flame shape are then transported by convection towards the flame tip with the restorative time scale. The impact of radial non-uniformity in equivalence ratio perturbations on the flame impulse response is demonstrated by comparing the impulse responses for uniform and parabolic radial profiles. Considerable deviation in the phase of the flame transfer function, which is important for thermo-acoustic stability, is observed.

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