Predictions of NO and CO emissions in ammonia/methane/air combustion by LES using a non-adiabatic flamelet generated manifold

Honzawa, Takafumi; Kai, Reo; Okada, Akiko; Valera‐Medina, Agustin; Bowen, Philip John; Kurose, Ryoichi

doi:10.1016/j.energy.2019.07.101

Cited by 77 publications

(17 citation statements)

References 31 publications

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“…182 Later on, Xiao et al 265,266 carried out the reduction of pre-existing ammonia/hydrocarbon mechanisms to have good accuracy with the experimental results and reduce the computational time at the same time. The LES work by Honzawa et al 267 demonstrated the use of these novel models, enabling the use of non-adiabatic conditions, which delivered more representative and realistic results than those obtained in the literature.…”

Section: Applicationsmentioning

confidence: 99%

Review on Ammonia as a Potential Fuel: From Synthesis to Economics

et al. 2021

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Ammonia, a molecule that is gaining more interest as a fueling vector, has been considered as a candidate to power transport, produce energy, and support heating applications for decades. However, the particular characteristics of the molecule always made it a chemical with low, if any, benefit once compared to conventional fossil fuels. Still, the current need to decarbonize our economy makes the search of new methods crucial to use chemicals, such as ammonia, that can be produced and employed without incurring in the emission of carbon oxides. Therefore, current efforts in this field are leading scientists, industries, and governments to seriously invest efforts in the development of holistic solutions capable of making ammonia a viable fuel for the transition toward a clean future. On that basis, this review has approached the subject gathering inputs from scientists actively working on the topic. The review starts from the importance of ammonia as an energy vector, moving through all of the steps in the production, distribution, utilization, safety, legal considerations, and economic aspects of the use of such a molecule to support the future energy mix. Fundamentals of combustion and practical cases for the recovery of energy of ammonia are also addressed, thus providing a complete view of what potentially could become a vector of crucial importance to the mitigation of carbon emissions. Different from other works, this review seeks to provide a holistic perspective of ammonia as a chemical that presents benefits and constraints for storing energy from sustainable sources. State-of-the-art knowledge provided by academics actively engaged with the topic at various fronts also enables a clear vision of the progress in each of the branches of ammonia as an energy carrier. Further, the fundamental boundaries of the use of the molecule are expanded to real technical issues for all potential technologies capable of using it for energy purposes, legal barriers that will be faced to achieve its deployment, safety and environmental considerations that impose a critical aspect for acceptance and wellbeing, and economic implications for the use of ammonia across all aspects approached for the production and implementation of this chemical as a fueling source. Herein, this work sets the principles, research, practicalities, and future views of a transition toward a future where ammonia will be a major energy player.

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Section: Applicationsmentioning

confidence: 99%

Review on Ammonia as a Potential Fuel: From Synthesis to Economics

et al. 2021

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“…The lack of the ORZ and lower temperatures resulted in a great divergence of the local NO concentration for the calculated emission values-1641 ppmv and 2318 ppmv, for 15 kW and 30 KW respectively. Boundary conditions (BC) connected with the heat exchange process need to be carefully defined in order to get a high accuracy of the NO predictions, which was in accordance to observations in [16,41].…”

Section: Surfacementioning

confidence: 65%

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

Jójka

Ślefarski

2021

Energies

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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.

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“…where Y i is the species mass fraction, ρ is density, F k,j the diffusion flux components, u j the velocity, f the mean reaction rate multiplier, and Y i * is the mass fraction at the end of a time integration τ (42). In order to account for non-adiabatic conditions in the system (i.e., which are known to produce higher NOx and lower NH 3 consequence of higher reactivity [44]), tests were conducted in a high-pressure optical combustor (HPOC) and validated with results [49] carried out in previous campaigns. A wall temperature of 1450 K was employed.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, this study focuses on the use of a novel reaction model (i.e., that includes advanced ammonia/hydrogen settings and methane reactions from well-known predecessors) used in previous modelling campaigns [44] to determine the exhaust profile of an industrial gas turbine combustor fueled with ammonia and hydrogen, seeking to understand how the addition of hydrogen at high concentrations impacts the overall chemistry and flame profile of the system. Further details of such model are presented below.…”

Section: Work Performed Bymentioning

confidence: 99%

Numerical Predictions of a Swirl Combustor Using Complex Chemistry Fueled with Ammonia/Hydrogen Blends

et al. 2020

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Ammonia, a chemical that contains high hydrogen quantities, has been presented as a candidate for the production of clean power generation and aerospace propulsion. Although ammonia can deliver more hydrogen per unit volume than liquid hydrogen itself, the use of ammonia in combustion systems comes with the detrimental production of nitrogen oxides, which are emissions that have up to 300 times the greenhouse potential of carbon dioxide. This factor, combined with the lower energy density of ammonia, makes new studies crucial to enable the use of the molecule through methods that reduce emissions whilst ensuring that enough power is produced to support high-energy intensive applications. Thus, this paper presents a numerical study based on the use of novel reaction models employed to characterize ammonia combustion systems. The models are used to obtain Reynolds Averaged Navier-Stokes (RANS) simulations via Star-CCM+ with complex chemistry of a 70%–30% (mol) ammonia–hydrogen blend that is currently under investigations elsewhere. A fixed equivalence ratio (1.2), medium swirl (0.8), and confined conditions are employed to determine the flame and species propagation at various operating atmospheres and temperature inlet values. The study is then expanded to high inlet temperatures, high pressures, and high flowrates at different confinement boundary conditions. The results denote how the production of NOx emissions remains stable and under 400 ppm, whilst higher concentrations of both hydrogen and unreacted ammonia are found in the flue gases under high power conditions. The reduction of heat losses (thus higher temperature boundary conditions) has a crucial impact on further destruction of ammonia post-flame, with a raise in hydrogen, water, and nitrogen through the system, thus presenting an opportunity of combustion efficiency improvement of this blend by reducing heat losses. Final discussions are presented as a method to raise power whilst employing ammonia for gas turbine systems.

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Predictions of NO and CO emissions in ammonia/methane/air combustion by LES using a non-adiabatic flamelet generated manifold

Cited by 77 publications

References 31 publications

Review on Ammonia as a Potential Fuel: From Synthesis to Economics

Review on Ammonia as a Potential Fuel: From Synthesis to Economics

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

Numerical Predictions of a Swirl Combustor Using Complex Chemistry Fueled with Ammonia/Hydrogen Blends

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