MILD Combustion of Methanol, Ethanol and 1-Butanol binary blends with Ammonia

Ariemma, Giovanni Battista; Sorrentino, Giancarlo; Sabia, Pino; Ragucci, Raffaele; Joannon, M. de

doi:10.1016/j.proci.2022.08.032

Cited by 37 publications

(4 citation statements)

References 24 publications

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“…Literature studies in this field showed that, due to its intrinsic characteristic to be fuel flexible, ammonia MILD Combustion with other fuels can be easily achieved in a single unit. In particular, ammonia/methane and ammonia/alcohols blends were experimentally investigated in a lab-scale cyclonic burner [12], [13]. Experiments confirmed that both alcohols and methane are able to extend the stable operational window of ammonia, in terms of both working temperatures and equivalence ratios.…”

Section: Figure 3 System Temperature and Nox As Function Of Equivalen...mentioning

confidence: 94%

Ammonia as a Fuel for Gas Turbines: Perspectives and Challenges

Langella,

Sorrentino,

Sabia

et al. 2023

J. Phys.: Conf. Ser.

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The paper addresses the prospects and challenges associated with the use of ammonia in gas turbine plants. The complexity of the chemical kinetic mechanisms of ammonia combustion and the insufficient amount of experimental data that can confirm the results still require a lot of scientific research. In this sense, this application is even less technologically mature than other sectors such as the marine engine one. From the point of view of combustion in gas turbines, the techniques in use and being perfected to deal with flame instability, low laminar burning velocity (about 20% of that of methane-air flames), the long ignition delay time and low volumetric heat release rate. In particular, the use of ammonia blended with other combustion enhancers such as hydrogen, methane and alcohols has been analyzed. Mild combustion is also being analyzed as a valid technique for dealing with the difficulties of ammonia combustion. The combustion of ammonia generates significant quantities of nitrogen oxides, both for the thermal mechanism and for the “fuel” one, which must therefore be mitigated, together with the emission of unburnt ammonia. Even in this case, blending with other fuels allows for improved emissions performance. The paper compares the different techniques and the relative advantages both in terms of combustion efficiency and emissions. Finally, the perspectives for the use of ammonia in gas turbines are outlined, highlighting the challenges still to be overcome, in a panorama of energy transition towards an increasingly decarbonized future, with the aim of mitigating climate change as much as possible.

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Section: Figure 3 System Temperature and Nox As Function Of Equivalen...mentioning

confidence: 94%

Ammonia as a Fuel for Gas Turbines: Perspectives and Challenges

Langella,

Sorrentino,

Sabia

et al. 2023

J. Phys.: Conf. Ser.

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“…Consequently, the maximum NO x emissions were obtained at volumetric fractions of ammonia between 25 and 50%. A later work by Ariemma et al showed a nonlinear behavior of NO x and AES for ammonia/alcohol blends. Compared with mixtures of ammonia and methane, the peak in NO x emission is shifted to higher AES in blends of ammonia and alcohols.…”

Section: Introductionmentioning

confidence: 91%

Ammonia in Dual-Fueled Internal Combustion Engines: Impact on NO_x, N₂O, and Soot Formation

Pedersen,

Lewandowski,

Schulze-Netzer

et al. 2023

Energy Fuels

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The combustion of ammonia in internal combustion engines (ICE) releases nitrogen-related exhaust emissions. Numerous studies have shown that the increased formation of nitrous oxide (N 2 O) may offset ammonia's carbon-free advantages, leading to a higher greenhouse gas potential than fossil fuels. Moreover, nitrogen contained in ammonia further promotes an increase in NO x formation. This study aims to expand the understanding of emission formation in dual-fuel ICEs when using ammonia as a fuel. By constant-pressure reactor simulations coupled with detailed reaction kinetics, the concept of equivalence ratio−temperature diagrams was employed to characterize conditions featuring high NO x , N 2 O, and soot concentrations. The diagrams were obtained for pure ammonia, pure n-heptane, and three blends with ammonia energy shares (AES) of 20, 50, and 80%. Our findings strengthen the perception that high concentrations of N 2 O in ICEs are related to incomplete combustion. A higher AES leads to increased N 2 O concentration during the ignition, going from single-digit ppm levels for pure n-heptane to conditions featuring levels 3 orders of magnitude higher for pure ammonia. In fully burned mixtures, N 2 O emissions feature a low fuel dependency and single-digit concentration levels only at low equivalence ratios and high temperatures. Further, varying contributions from the fuel NO, prompt NO, and thermal De-NO x mechanisms were observed with fuel composition; however, the thermal NO contribution led to a fuel-independent behavior for NO x emissions at temperatures above 2600 K. The soot concentration decreases as the carbon content in the fuel decreases. In our configuration, the lowest equivalence ratio at which the 0.1% soot yield limit was observed was 2.20 for pure n-heptane, 2.65 for AES of 20%, 5.05 for 50% AES, and not attained for higher AES. Ultimately, it was found that in fuel-rich regimes and at fully burned conditions, low concentrations of NO x and N 2 O emissions are observed.

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“…The reactor employed for the experimental investigation is the laboratory unit cyclonic burner (LUCY) developed at STEMS–CNR, extensively described in previous works. ,, Briefly, as illustrated in Figure , the burner consists of an atmospheric 2000 cm 3 prismatic combustion chamber, equipped with an antisymmetrical reactant feeding system consisting of two couples of oxidizer and fuel nozzles, placed orthogonally with respect to the outlet section, which is located in the center of the bottom face of the reactor. Such a peculiar design allows for the establishment of a cyclonic flow field, which ensures a strong internal recirculation of mass and sensible enthalpy, by diluting the fresh reactants and increasing the temperature above the autoignition temperature.…”

Section: Experimental Apparatusmentioning

confidence: 99%

Performance Assessment of Modeling Approaches for Moderate or Intense Low-Oxygen Dilution Combustion in a Scale-Bridging Burner

Giuntini,

Frascino,

Ariemma

et al. 2023

Energy Fuels

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The present work provides deep insights into methane oxidation in a cyclonic flow field chamber whose strong internal recirculation of burnt products enables the attainment of a moderate or intense low-oxygen dilution (MILD) combustion regime over a wide range of operating conditions. Steady-state Favreaveraged Navier−Stokes (FANS) simulations are performed to evaluate the thermochemical processes taking place within the reactor and to assess the suitability of existing computational fluid dynamics (CFD) models to describe the turbulence−chemistry interactions in such a scale-bridging configuration. A sensitivity analysis is carried out with respect to different turbulence closure models [i.e., renormalization group (RNG) k−ε, realizable k−ε, and Reynolds stress model], kinetic mechanisms (i.e., KEE-58 and GRI-Mech 2.11), as well as different turbulent combustion approaches, i.e., the flamelet generated manifold (FGM), the eddy dissipation concept (EDC), and the partially stirred reactor (PaSR) models. The accuracy of numerical predictions is assessed by a direct comparison to obtained experimental results in terms of temperature profiles locally collected within the reactor and flue gas compositions monitored at the exit of the burner. Results highlight that the EDC and PaSR methods are the most suitable modeling paradigms for the investigated MILD combustion conditions, although the former may likely predict an extinction of the combustion process; conversely, the FGM model shows the largest discrepancies with respect to experimental data, highlighting the need for improvements.

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MILD Combustion of Methanol, Ethanol and 1-Butanol binary blends with Ammonia

Cited by 37 publications

References 24 publications

Ammonia as a Fuel for Gas Turbines: Perspectives and Challenges

Ammonia as a Fuel for Gas Turbines: Perspectives and Challenges

Ammonia in Dual-Fueled Internal Combustion Engines: Impact on NO_x, N₂O, and Soot Formation

Performance Assessment of Modeling Approaches for Moderate or Intense Low-Oxygen Dilution Combustion in a Scale-Bridging Burner

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MILD Combustion of Methanol, Ethanol and 1-Butanol binary blends with Ammonia

Cited by 37 publications

References 24 publications

Ammonia as a Fuel for Gas Turbines: Perspectives and Challenges

Ammonia as a Fuel for Gas Turbines: Perspectives and Challenges

Ammonia in Dual-Fueled Internal Combustion Engines: Impact on NOx, N2O, and Soot Formation

Performance Assessment of Modeling Approaches for Moderate or Intense Low-Oxygen Dilution Combustion in a Scale-Bridging Burner

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Product

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Ammonia in Dual-Fueled Internal Combustion Engines: Impact on NO_x, N₂O, and Soot Formation