Application of Dielectric Barrier Discharge to Improve the Flashback Limit of a Lean Premixed Dump Combustor

2011 ◽  
Vol 134 (3) ◽  
Author(s):  
Philippe Versailles ◽  
Wajid Ali Chishty ◽  
Huu Duc Vo
Keyword(s):  
Natural Gas ◽  
Dielectric Barrier Discharge ◽  
Flow Rate ◽  
Gas Turbines ◽  
Barrier Discharge ◽  
Operating Conditions ◽  
Diffusion Type ◽  
Dielectric Barrier ◽  
Fuel Flow ◽  
Lean Premixed

In recent years, lean-premixed (LP) combustors have been widely studied due to their potential to reduce NOx emissions in comparison to diffusion type combustors. However, the fact that the fuels and oxidizers are mixed upstream of the combustion zone makes LP type of combustors a candidate for upstream flame propagation (i.e., flashback) in the premixer that is typically not designed to sustain high temperatures. Moreover, there has been a recent demand for fuel-flexible gas turbines that can operate on hydrogen-enriched fuels like Syngas. Combustors originally designed for slower kinetics fuels like natural gas can potentially encounter flashback if operated with faster burning fuels like those containing hydrogen as a constituent. There exists a clear need in fuel-flexible lean-premixed combustors to control flashback that will not only prevent costly component damage but will also enhance the operability margin of engines. A successful attempt has been made to control flashback in an atmospheric LP combustor, burning natural gas-air mixtures, via the application of dielectric barrier discharge (DBD). A low-power DBD actuator was designed, fabricated and integrated into a premixer made out of quartz. The actuator was tuned to produce a low magnitude ionic wind with an intention to modify the velocity profile in the premixer. Flashback conditions were created by decreasing the air flow rate while keeping the fuel flow rate constant. Within this experimental setup, flashback happened in the core flow along the axis of the cylindrical premixer. Results show that the utilization of the DBD delays the occurrence of flashback to higher equivalence ratios. Improvements as high as about 5% of the flashback limit have been obtained without compromising the blowout limit. It is anticipated that this novel application of DBD will lead to future demonstrations of the concept under realistic gas turbine operating conditions.

Application of Dielectric Barrier Discharge to Improve the Flashback Limit of a Lean Premixed Dump Combustor

2011 ◽  
Author(s):  
Philippe Versailles ◽  
Wajid Ali Chishty ◽  
Huu Duc Vo
Keyword(s):  
Natural Gas ◽  
Dielectric Barrier Discharge ◽  
Flow Rate ◽  
Gas Turbines ◽  
Barrier Discharge ◽  
Operating Conditions ◽  
Diffusion Type ◽  
Dielectric Barrier ◽  
Fuel Flow ◽  
Lean Premixed

In recent years, lean-premixed (LP) combustors have been widely studied due to their potential to reduce NOx emissions in comparison to diffusion type combustors. However, the fact that the fuels and oxidizers are mixed upstream of the combustion zone makes LP type of combustors a candidate for upstream flame propagation (i.e., flashback) in the premixer that is typically not designed to sustain high temperatures. Moreover, there has been a recent demand for fuel-flexible gas turbines that can operate on hydrogen-enriched fuels like Syngas. Combustors originally designed for slower kinetics fuels like natural gas can potentially encounter flashback if operated with faster burning fuels like those containing hydrogen as a constituent. There exists a clear need in fuel-flexible lean-premixed combustors to control flashback that will not only prevent costly component damage but will also enhance the operability margin of engines. A successful attempt has been made to control flashback in an atmospheric LP combustor, burning natural gas-air mixtures, via the application of Dielectric Barrier Discharge (DBD). A low-power DBD actuator was designed, fabricated and integrated into a premixer made out of quartz. The actuator was tuned to produce a low magnitude ionic wind with an intention to modify the velocity profile in the premixer. Flashback conditions were created by decreasing the air flow rate while keeping the fuel flow rate constant. Within this experimental setup, flashback happened in the core flow along the axis of the cylindrical premixer. Results show that the utilization of the DBD delays the occurrence of flashback to higher equivalence ratios. Improvements as high as about 5% of the flashback limit have been obtained without compromising the blowout limit. It is anticipated that this novel application of DBD will lead to future demonstrations of the concept under realistic gas turbine operating conditions.

Impact of Fuel Composition on Blow Off and Flashback in Swirl Stabilized Lean Premixed Combustion

2013 ◽  
Author(s):  
Amin Akbari ◽  
Vincent McDonell ◽  
Scott Samuelsen
Keyword(s):  
Natural Gas ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Pollutant Emissions ◽  
Fuel Composition ◽  
Pure Hydrogen ◽  
Combustion Properties ◽  
Lean Premixed ◽  
The Impact

Co firing of natural gas with renewable fuels such as hydrogen can reduce greenhouse gas emissions, and meet other sustainability considerations. At the same time, adding hydrogen to natural gas alters combustion properties, such as burning speeds, heating values, flammability limits, and chemical characteristics. It is important to identify how combustion stability relates to fuel mixture composition in industrial gas turbines and burners and correlate such behavior to fuel properties or operating conditions. Ultimately, it is desired to predict and prevent operability issues when designing a fuel flexible gas turbine combustor. Fuel interchangeability is used to describe the ability of a substitute fuel composition to replace a baseline fuel without significantly altering performance and operation. Any substitute fuel, while maintaining the same heating load as the baseline fuel, must also provide stable combustion with low pollutant emissions. Interchangeability indices try to predict the impact of fuel composition on lean blowoff and flashback. Correlations for operability limits have been reported, though results are more consistent for blowoff compared to flashback. Yet, even for blowoff, some disagreement regarding fuel composition effects are evident. In the present work, promising correlations and parameters for lean blow off and flashback in a swirl stabilized lean premixed combustor are evaluated. Measurements are conducted for fuel compositions ranging from pure natural gas to pure hydrogen under different levels of preheat and air flow rates. The results are used to evaluate the ability of existing approaches to predict blowoff and flashback. The results show that, while a Damköhler number approach for blowoff is promising, important considerations are required in applying the method. For flashback, the quench constant parameter suggested for combustion induced vortex breakdown was applied and found to have limited success for predicting flashback in the present configuration.

scholarly journals Experimental Investigation of the Liquid Fuel Evaporation in a Premix Duct for Lean Premixed and Prevaporized Combustion

1996 ◽  
Author(s):  
Michael Brandt ◽  
Kay O. Gugel ◽  
Christoph Hassa
Keyword(s):  
Experimental Investigation ◽  
Air Temperature ◽  
Flow Rate ◽  
Liquid Fuel ◽  
Operating Conditions ◽  
Dispersion Characteristics ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Lean Premixed ◽  
Fuel Evaporation

Liquid fuel evaporation was investigated in a premix duct, operating at conditions expected for lean premixed and prevaporized combustion. Results from a flat prefilming airblast atomizer are presented. Kerosine Jet A was used in all experiments. Air pressure, air temperature and liquid fuel flow rate were varied separately, their relative influences on atomization, evaporation and fuel dispersion are discussed. The results show, that at pressures up to 15 bars and temperatures up to 850 K, nearly complete evaporation of the fuel was achieved, without autoignition of the fuel. For the configuration tested, the fuel distributions of the liquid and evaporated fuel sbow very little differences in their dispersion characteristics and were not much affected by a variation of the operating conditions.

Removal of Toluene by Dielectric Barrier Discharge Combined with Modified Photocatalyst

2015 ◽  
Vol 737 ◽  
pp. 561-564
Author(s):  
Jing Xin Li ◽  
Bao Hui Li ◽  
Zhi Yong Li
Keyword(s):  
Energy Efficiency ◽  
Dielectric Barrier Discharge ◽  
Flow Rate ◽  
Gas Flow ◽  
Barrier Discharge ◽  
Gas Flow Rate ◽  
Dielectric Barrier ◽  
Optimal Doping ◽  
Initial Concentration ◽  
Doping Ratio

The toluene being removed by dielectric barrier discharge (DBD) combined with modified photocatalyst was studied in the paper. Transition metal manganese was doped into crystal lattice of TiO2 in order to improve the activity of photocatalyst, and the optimal doping ratio was confirmed in the study. As one of main factors, the influence on toluene removal efficiency of gas flow rate, initial concentration and electric field intensity was analyzed in the study. Furthermore, the energy efficiency was another important index which had been compared amongγ-Al2O3, TiO2/γ-Al2O3 and Mn-TiO2/γ-Al2O3. The result of study showed that DBD combined with Mn-TiO2/γ-Al2O3 had the best buffer action against increasing of gas flow rate and initial concentration, the energy efficiency had the tendency as Mn-TiO2/γ-Al2O3 > TiO2/γ-Al2O3>γ-Al2O3, and the optimal doping ratio of manganese was 0.01.

scholarly journals Effects of plasma kinetic modeling on performance characterization of plasma actuators for active flow control

2020 ◽  
Vol 197 ◽  
pp. 10004
Author(s):  
Donato Fontanarosa ◽  
Giacomo Cinieri ◽  
Maria Grazia De Giorgi ◽  
Antonio Ficarella
Keyword(s):  
Charge Density ◽  
Dielectric Barrier Discharge ◽  
Barrier Discharge ◽  
Fluid Model ◽  
Active Flow Control ◽  
Operating Conditions ◽  
Dielectric Barrier ◽  
Plasma Kinetics ◽  
Model Based ◽  
Plasma Reactions

This work focuses on the development of a multiscale computational fluid dynamics (CFD) simulation framework for the investigation of the effects of plasma kinetics on the performance of a microscale dielectric barrier discharge plasma actuator (DBD-PA). To this purpose, DBD-PA multi-scale dual-step modelling approach has been implemented, by considering plasma chemistry and flow dynamic. At first, a microscopic plasma model based on the air plasma kinetics has been defined and plasma reactions have been simulated in zero-dimensional computations in order to evaluate the charge density. At this aim computations have been performed using the toolbox ZDPlasKin, which solves plasma reactions by means of Bolsig+ solver. An alternate current (AC) electrical feeding has been assumed: in particular, the sinusoidal voltage amplitude and the frequency have been fixed at 5 kV and 1 kHz at atmospheric pressure and 300 K temperature in quiescent environment. The predictal charge density has been in a macroscopic plasma-fluid model based on Suzen Dual Potential Model (DPM), which has implemented in the computation fluid dynamic CFD code OpenFoam. Hence, as second step, 2D-CFD simulations of the electro-hydrodynamic body forces induced by the microscale DBDPA have been performed, based on the previously predicted charge densities at the operating conditions. Quiescent flow over a dielectric barrier discharge actuator has been simulated using the plasma-fluid model. The novel modelling framework has been validated with experimental data.

scholarly journals Transition from diffuse to self-organized discharge in a high frequency dielectric barrier discharge

2017 ◽  
Vol 79 (1) ◽  
pp. 10802 ◽  
Author(s):  
Antoine Belinger ◽  
Nicolas Naudé ◽  
Nicolas Gherardi
Keyword(s):  
Dielectric Barrier Discharge ◽  
Memory Effect ◽  
High Frequency ◽  
Barrier Discharge ◽  
Critical Role ◽  
Operating Conditions ◽  
The Self ◽  
Dielectric Barrier ◽  
Self Organized

Depending on the operating conditions, different regimes can be obtained in a dielectric barrier discharge (DBD): filamentary, diffuse (also called homogeneous) or self-organized. For a plane-to-plane DBD operated at high frequency (160 kHz) and at atmospheric pressure in helium gas, we show that the addition of a small amount of nitrogen induces a transition from the diffuse regime to a self-organized regime characterized by the appearance of filaments at the exit of the discharge. In this paper, we detail mechanisms that could be responsible of the transition from diffuse mode to this self-organized mode. We point out the critical role of the power supply and the importance of the gas memory effect from one discharge to the following one on the transition to the self-organised mode. The self-organized mode is usually attributed to a surface memory effect. In this work, we show an additional involvement of the gas memory effect on the self-organized mode.

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