SFGP 2007 - Natural Gas/Hydrogen Mixture Combustion in a Porous Radiant Burner

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Ségolène Gauthier ◽  
Etienne Lebas ◽  
Dominique Baillis
Keyword(s):  
Natural Gas ◽  
Experimental Tests ◽  
Premixed Combustion ◽  
Pollutant Emissions ◽  
Metallic Foam ◽  
Combustion Mode ◽  
Hydrogen Addition ◽  
Porous Burner ◽  
Hydrogen Mixtures ◽  
Radiant Burners

Within the context of reducing the green house gas emissions, substituting hydrogen for natural gas could have a great environmental impact, but hydrogen has different combustion characteristics than natural gas. This paper reports results of experimental tests of premixed combustion of natural gas-hydrogen mixtures in a porous burner made of open cell metallic foam. The technology of porous radiant burners shows environmental and economical advantages compared to traditional diffusion flame burners. The tests showed that substituting natural gas for hydrogen in a porous burner reduces the pollutant emissions of CO and NOx and the quantity of CO2 produced. For specific powers below 500 kW/m2, the emissions were below the "Blue Angel" label values. But working conditions are limited by hydrogen addition and the equivalence ratio has to be lowered to prevent flashback. The radiant combustion mode is more difficult to obtain with mixtures containing hydrogen and it disappears completely for mixtures with more than 80% vol. hydrogen.

scholarly journals Numerical investigation of fuel flexibility in a small-scale flameless combustor

2021 ◽  
Vol 2116 (1) ◽  
pp. 012017
Author(s):  
P Rijo ◽  
P J Coelho
Keyword(s):  
Numerical Simulation ◽  
Natural Gas ◽  
Numerical Investigation ◽  
Equivalence Ratio ◽  
Alternative Fuels ◽  
Premixed Combustion ◽  
Small Scale ◽  
Combustion Mode ◽  
Geometrical Characteristics ◽  
Fuel Flexibility

Abstract Numerical simulation of a laboratory flameless combustor was performed to investigate the flexibility to burn alternative fuels to natural gas. The studied fuels are biogas, syngas and a mixture of ammonia and methane. The inlet temperatures of air and fuel, the equivalence ratio and the geometrical characteristics of the combustor were maintained constant. The results show that flameless combustion is observed in the biogas and in the NH3/CH4 mixture, while the syngas burns according to the conventional non-premixed combustion mode. According to the predictions, the biogas emits 1.1 ppm of NOx and 229 ppm of CO, syngas produces 7.8 ppm of NOx and 35 ppm of CO and the NH3/CH4 mixture emits about 3900 ppm of NOx and 608 ppm of CO. The high NOx and CO emissions in the NH3/CH4 mixture show that the combustor needs to be optimized to burn a nitrogen-containing fuel.

scholarly journals Hydrogen Addition to Natural Gas in Cogeneration Engines: Optimization of Performances Through Numerical Modeling

2021 ◽  
Vol 7 ◽  
Author(s):  
Michela Costa ◽  
Daniele Piazzullo ◽  
Alessandro Dolce
Keyword(s):  
Natural Gas ◽  
Numerical Study ◽  
Pressure Rise ◽  
Pollutant Emissions ◽  
Lower Amount ◽  
Combustion Model ◽  
Exhaust Gases ◽  
Hydrogen Addition ◽  
Mixture Density ◽  
Brake Power

A numerical study of the energy conversion process occurring in a lean-charge cogenerative engine, designed to be powered by natural gas, is here conducted to analyze its performances when fueled with mixtures of natural gas and several percentages of hydrogen. The suitability of these blends to ensure engine operations is proven through a zero–one-dimensional engine schematization, where an original combustion model is employed to account for the different laminar propagation speeds deriving from the hydrogen addition. Guidelines for engine recalibration are traced thanks to the achieved numerical results. Increasing hydrogen fractions in the blend speeds up the combustion propagation, achieving the highest brake power when a 20% of hydrogen fraction is considered. Further increase of this last would reduce the volumetric efficiency by virtue of the lower mixture density. The formation of the NOx pollutants also grows exponentially with the hydrogen fraction. Oppositely, the efficiency related to the exploitation of the exhaust gases’ enthalpy reduces with the hydrogen fraction as shorter combustion durations lead to lower temperatures at the exhaust. If the operative conditions are shifted towards leaner air-to-fuel ratios, the in-cylinder flame propagation speed decreases because of the lower amount of fuel trapped in the mixture, reducing the conversion efficiencies and the emitted nitrogen oxides at the exhaust. The link between brake power and spark timing is also highlighted: a maximum is reached at an ignition timing of 21° before top dead center for hydrogen fractions between 10 and 20%. However, the exhaust gases’ temperature also diminishes for retarded spark timings. Lastly, an optimization algorithm is implemented to individuate the optimal condition in which the engine is characterized by the highest power production with the minimum fuel consumption and related environmental impact. As a main result, hydrogen addition up to 15% in volume to natural gas in real cogeneration systems is proven as a viable route only if engine operations are shifted towards leaner air-to-fuel ratios, to avoid rapid pressure rise and excessive production of pollutant emissions.

A phenomenological model for the description of unburned hydrocarbons emission in ultra-lean engines

2021 ◽  
pp. 146808742110050
Author(s):  
Enrica Malfi ◽  
Vincenzo De Bellis ◽  
Fabio Bozza ◽  
Alberto Cafari ◽  
Gennaro Caputo ◽  
...  
Keyword(s):  
Natural Gas ◽  
Internal Combustion Engines ◽  
Pollutant Emissions ◽  
Average Error ◽  
Combustion Engines ◽  
Nitric Oxides ◽  
Lean Burn ◽  
Fuel Charge ◽  
Unburned Hydrocarbons ◽  
Model Reliability

The adoption of lean-burn concepts for internal combustion engines working with a homogenous air/fuel charge is under development as a path to simultaneously improve thermal efficiency, fuel consumption, nitric oxides, and carbon monoxide emissions. This technology may lead to a relevant emission of unburned hydrocarbons (uHC) compared to a stoichiometric engine. The uHC sources are various and the relative importance varies according to fuel characteristics, engine operating point, and some geometrical details of the combustion chamber. This concern becomes even more relevant in the case of engines supplied with natural gas since the methane has a global warming potential much greater than the other major pollutant emissions. In this work, a simulation model describing the main mechanisms for uHC formation is proposed. The model describes uHC production from crevices and flame wall quenching, also considering the post-oxidation. The uHC model is implemented in commercial software (GT-Power) under the form of “user routine”. It is validated with reference to two large bore engines, whose bores are 31 and 46 cm (engines named accordingly W31 and W46). Both engines are fueled with natural gas and operated with lean mixtures (λ > 2), but with different ignition modalities (pre-chamber device or dual fuel mode). The engines under study are preliminarily schematized in the 1D simulation tool. The consistency of 1D engine schematizations is verified against the experimental data of BMEP, air flow rate, and turbocharger rotational speed over a load sweep. Then, the uHC model is validated against the engine-out measurements. The averaged uHC predictions highlight an average error of 7% and 10 % for W31 and W46 engines, respectively. The uHC model reliability is evidenced by the lack of need for a case-dependent adjustment of its tuning constants, also in presence of relevant variations of both engine load and ring pack design.

scholarly journals CFD Study and Experimental Validation of a Dual Fuel Engine: Effect of Engine Speed

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4307
Author(s):  
Roberta De Robbio ◽  
Maria Cristina Cameretti ◽  
Ezio Mancaruso ◽  
Raffaele Tuccillo ◽  
Bianca Maria Vaglieco
Keyword(s):  
Natural Gas ◽  
High Performance ◽  
Engine Speed ◽  
Pollutant Emissions ◽  
Dual Fuel ◽  
Automotive Market ◽  
Light Duty ◽  
Viable Solution ◽  
Dual Fuel Engines ◽  
Gas Ratio

Dual fuel engines induce benefits in terms of pollutant emissions of PM and NOx together with carbon dioxide reduction and being powered by natural gas (mainly methane) characterized by a low C/H ratio. Therefore, using natural gas (NG) in diesel engines can be a viable solution to reevaluate this type of engine and to prevent its disappearance from the automotive market, as it is a well-established technology in both energy and transportation fields. It is characterized by high performance and reliability. Nevertheless, further improvements are needed in terms of the optimization of combustion development, a more efficient oxidation, and a more efficient exploitation of gaseous fuel energy. To this aim, in this work, a CFD numerical methodology is described to simulate the processes that characterize combustion in a light-duty diesel engine in dual fuel mode by analyzing the effects of the changes in engine speed on the interaction between fluid-dynamics and chemistry as well as when the diesel/natural gas ratio changes at constant injected diesel amount. With the aid of experimental data obtained at the engine test bench on an optically accessible research engine, models of a 3D code, i.e., KIVA-3V, were validated. The ability to view images of OH distribution inside the cylinder allowed us to better model the complex combustion phenomenon of two fuels with very different burning characteristics. The numerical results also defined the importance of this free radical that characterizes the areas with the greatest combustion activity.

Effect of thermal input, excess air coefficient and combustion mode on natural gas MILD combustion in industrial-scale furnace

Fuel ◽  
2021 ◽  
Vol 302 ◽  
pp. 121179
Author(s):  
Mingming Huang ◽  
Ruichuan Li ◽  
Jikang Xu ◽  
Shen Cheng ◽  
Haoxin Deng ◽  
...  
Keyword(s):  
Natural Gas ◽  
Industrial Scale ◽  
Combustion Mode ◽  
Mild Combustion ◽  
Excess Air ◽  
Excess Air Coefficient
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