Effect of hydrogen addition on the ionization of partially premixed methane flame

Effect of hydrogen addition in methane-air premixed flames has been examined from a swirl stabilized combustor under confined flame conditions. Different swirlers have been examined to investigate the effect of swirl intensity on enriching methane-air flame with hydrogen in a laboratory-scale pre-mixed combustor operated at 5.81 kW. The flame stability was examined at same head load (5.81 kW) for various parameters such as amount of hydrogen addition, combustion air flow rates and swirl strengths. This was done by comparing adiabatic flame temperatures at the lean flame limit. The combustion characteristics of hydrogen enriched methane flames at constant heat load but different swirl strength were examined using particle image velocimetry (PIV), OH chemiluminescence, micro-thermocouples diagnostics to provide information on velocity and temperature field, and combustion generated OH concentration in the flame. Gas analyzer was used to obtain NOx and CO concentration at the exit. The results show that the the lean stability limit is mostly extended by hydrogen addition, but it can reduce in case of higher swirl intensity operating at lower adiabatic flame temperatures. The addition of hydrogen increases the NOx emission; however, this effect can be reduced by increasing either the excess air or swirl intensity. The results of NOx and CO emissions were also compared with a diffusion flame type combustor. The NOx emissions of hydrogen enriched methane premixed flame was found to be lower than the corresponding diffusion flame under the fuel lean condition.

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Effects of Hydrogen Addition on Swirl-Stabilized Flame Properties

Volume 2: Combustion, Fuels and Emissions, Parts A and B ◽

10.1115/gt2010-23686 ◽

2010 ◽

Author(s):

Shengrong Zhu ◽

Sumanta Acharya

Keyword(s):

Flame Front ◽

Surface Density ◽

Recirculation Zone ◽

Burning Velocity ◽

Mie Scattering ◽

Reacting Flow ◽

Flame Surface ◽

Flame Surface Density ◽

Hydrogen Addition ◽

Methane Flame

The role of hydrogen addition to swirl-stabilized methane flames is studied experimentally. Of specific interest are flame properties including flame surface density and curvature. The measurements are based on Particle Image Velocimetry (PIV), Mie-scattering and CH-chemiluminescence imaging. Identification of the flame front and its geometric characterization provides an understanding of the flame properties. Compared to the non-reacting flow, the methane flame broadens the central recirculation zone. Hydrogen enriched flames reduce the central recirculation zone and scales down the characteristic length of the flow. With hydrogen addition, the distribution of the flame front curvature is broadened and flame surface density is increased. This indicates that hydrogen addition increases the reaction front thermo-diffusive instability, causing the flame front to be more wrinkled, and increasing the flame surface area leading to an increase in the burning velocity.

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Lean Partially Premixed Combustion Investigation of Methane Direct-Injection Under Different Characteristic Parameters

Volume 1: Large Bore Engines; Advanced Combustion; Emissions Control Systems; Instrumentation, Controls, and Hybrids ◽

10.1115/icef2013-19034 ◽

2013 ◽

Author(s):

Omid Askari ◽

Hameed Metghalchi ◽

Siamak Kazemzadeh Hannani ◽

Hadis Hemmati ◽

Reza Ebrahimi

Keyword(s):

Turbulent Combustion ◽

Maximum Rate ◽

Peak Pressure ◽

Pressure Rise ◽

Injection Pressure ◽

Pressure Chamber ◽

Chamber Pressure ◽

Simultaneous Increase ◽

Hydrogen Addition ◽

Partially Premixed

The effects of hydrogen addition, diluent addition, injection pressure, chamber pressure, chamber temperature and turbulence intensity on methane–air partially premixed turbulent combustion have been studied experimentally using a constant volume combustion chamber (CVCC). The fuel–air mixture was ignited by centrally located electrodes at given spark delay times of 1, 5, 40, 75 and 110 milliseconds. Experiments were performed for a wide range of hydrogen volumetric fractions (0% to 40%), exhaust gas recirculation (EGR) volumetric fractions (0% to 25% as a diluent), injection pressures (30–90 bar), chamber pressures (1–3 bar), chamber temperatures (298–432 K) and overall equivalence ratios of 0.6, 0.8, and 1.0. Flame propagation images via the Sclieren/Shadowgraph technique, combustions characteristics via pressure derived parameters and pollutant concentrations were analyzed for each set of conditions. The results showed that peak pressure and maximum rate of pressure rise increased with the increase in chamber pressure and temperature while changing injection pressure had no considerable effect on pressure and maximum rate of pressure rise. The peak pressure and maximum rate of pressure rise increased while combustion duration decreased with simultaneous increase of hydrogen content. The lean burn limit of methane–air turbulent combustion was improved with hydrogen addition. Addition of EGR increased combustion instability and misfiring while decreasing the emission of nitrogen oxides (NOx).

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Lean Partially Premixed Combustion Investigation of Methane Direct-Injection Under Different Characteristic Parameters

Journal of Energy Resources Technology ◽

10.1115/1.4026204 ◽

2014 ◽

Vol 136 (2) ◽

Cited By ~ 28

Author(s):

Omid Askari ◽

Hameed Metghalchi ◽

Siamak Kazemzadeh Hannani ◽

Hadis Hemmati ◽

Reza Ebrahimi

Keyword(s):

Turbulent Combustion ◽

Maximum Rate ◽

Peak Pressure ◽

Pressure Rise ◽

Injection Pressure ◽

Pressure Chamber ◽

Chamber Pressure ◽

Simultaneous Increase ◽

Hydrogen Addition ◽

Partially Premixed

The effects of hydrogen addition, diluent addition, injection pressure, chamber pressure, chamber temperature and turbulence intensity on methane–air partially premixed turbulent combustion have been studied experimentally using a constant volume combustion chamber (CVCC). The fuel–air mixture was ignited by centrally located electrodes at given spark delay times of 1, 5, 40, 75, and 110 ms. Experiments were performed for a wide range of hydrogen volumetric fractions (0% to 40%), simulated diluent volumetric fractions (0% to 25% as a diluent), injection pressures (30–90 bar), chamber pressures (1–3 bar), chamber temperatures (298–432 K) and overall equivalence ratios of 0.6, 0.8, and 1.0. Flame propagation images via the Schlieren/Shadowgraph technique, combustion characteristics via pressure derived parameters and pollutant concentrations were analyzed for each set of conditions. The results showed that peak pressure and maximum rate of pressure rise increased with the increase in chamber pressure and temperature while changing injection pressure had no considerable effect on pressure and maximum rate of pressure rise. The peak pressure and maximum rate of pressure rise increased, while combustion duration decreased with simultaneous increase of hydrogen content. The lean burn limit of methane–air turbulent combustion was improved with hydrogen addition. Addition of diluent increased combustion instability and misfiring while decreasing the emission of nitrogen oxides (NOx).

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