NO formation/reduction mechanisms of ammonia/air premixed flames at various equivalence ratios and pressures

Ammonia is a carbon-free fuel and its application to internal combustion engines is expected. However, few studies on ammonia flames, especially at high pressures, have been carried out because ammonia has not been considered to be a fuel owing to its lower combustion intensity. Most of NOx, which i...

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Autores principales:	Akihiro HAYAKAWA, Takashi GOTO, Rentaro MIMOTO, Taku KUDO, Hideaki KOBAYASHI
Formato:	article
Lenguaje:	EN
Publicado:	The Japan Society of Mechanical Engineers 2015
Materias:	combustion laminar flames ammonia nitrogen oxide equivalence ratio high pressure Mechanical engineering and machinery TJ1-1570
Acceso en línea:	https://doaj.org/article/9bc403d76a494fa7a3d8a93ed77ff296
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spelling	oai:doaj.org-article:9bc403d76a494fa7a3d8a93ed77ff2962021-11-26T06:16:58ZNO formation/reduction mechanisms of ammonia/air premixed flames at various equivalence ratios and pressures2187-974510.1299/mej.14-00402https://doaj.org/article/9bc403d76a494fa7a3d8a93ed77ff2962015-01-01T00:00:00Zhttps://www.jstage.jst.go.jp/article/mej/2/1/2_14-00402/_pdf/-char/enhttps://doaj.org/toc/2187-9745Ammonia is a carbon-free fuel and its application to internal combustion engines is expected. However, few studies on ammonia flames, especially at high pressures, have been carried out because ammonia has not been considered to be a fuel owing to its lower combustion intensity. Most of NOx, which is formed by ammonia combustion, is considered to be the fuel NOx. The objectives of this study were to investigate the fundamental characteristics of NOx experimentally, such as NO emission and chemiluminescence of ammonia/air flames not only at the atmospheric pressure but also under high pressures and to explore NO formation/reduction mechanisms using numerical simulation. Experiments were carried out using a nozzle-type burner. NH2 ammonia α band spectra were observed, and it was clarified that the color of ammonia flame is mainly determined by the NH2 ammonia α band and H2O spectra. Burned gas was sampled from ammonia flame stabilized at the burner. The mole fraction of NO decreased with the increase in equivalence ratio at atmospheric pressure. Reaction flow analysis was performed, and it was clarified that the decrease in the mole fraction of NO for rich mixtures was caused by NHi (i = 2, 1, 0). High pressure experiments were performed using a high pressure combustion facility for stoichiometric ammonia flame. Consequently, the decrease in the mole fraction of NO was experimentally observed and its tendency was found to qualitatively agree with the results of the numerical simulation. It was clarified that the third body reaction of OH + H + M ⇔ H2O + M plays an important role in the reduction of the mole fraction of NO at the high pressure.Akihiro HAYAKAWATakashi GOTORentaro MIMOTOTaku KUDOHideaki KOBAYASHIThe Japan Society of Mechanical Engineersarticlecombustionlaminar flamesammonianitrogen oxideequivalence ratiohigh pressureMechanical engineering and machineryTJ1-1570ENMechanical Engineering Journal, Vol 2, Iss 1, Pp 14-00402-14-00402 (2015)
institution	DOAJ
collection	DOAJ
language	EN
topic	combustion laminar flames ammonia nitrogen oxide equivalence ratio high pressure Mechanical engineering and machinery TJ1-1570
spellingShingle	combustion laminar flames ammonia nitrogen oxide equivalence ratio high pressure Mechanical engineering and machinery TJ1-1570 Akihiro HAYAKAWA Takashi GOTO Rentaro MIMOTO Taku KUDO Hideaki KOBAYASHI NO formation/reduction mechanisms of ammonia/air premixed flames at various equivalence ratios and pressures
description	Ammonia is a carbon-free fuel and its application to internal combustion engines is expected. However, few studies on ammonia flames, especially at high pressures, have been carried out because ammonia has not been considered to be a fuel owing to its lower combustion intensity. Most of NOx, which is formed by ammonia combustion, is considered to be the fuel NOx. The objectives of this study were to investigate the fundamental characteristics of NOx experimentally, such as NO emission and chemiluminescence of ammonia/air flames not only at the atmospheric pressure but also under high pressures and to explore NO formation/reduction mechanisms using numerical simulation. Experiments were carried out using a nozzle-type burner. NH2 ammonia α band spectra were observed, and it was clarified that the color of ammonia flame is mainly determined by the NH2 ammonia α band and H2O spectra. Burned gas was sampled from ammonia flame stabilized at the burner. The mole fraction of NO decreased with the increase in equivalence ratio at atmospheric pressure. Reaction flow analysis was performed, and it was clarified that the decrease in the mole fraction of NO for rich mixtures was caused by NHi (i = 2, 1, 0). High pressure experiments were performed using a high pressure combustion facility for stoichiometric ammonia flame. Consequently, the decrease in the mole fraction of NO was experimentally observed and its tendency was found to qualitatively agree with the results of the numerical simulation. It was clarified that the third body reaction of OH + H + M ⇔ H2O + M plays an important role in the reduction of the mole fraction of NO at the high pressure.
format	article
author	Akihiro HAYAKAWA Takashi GOTO Rentaro MIMOTO Taku KUDO Hideaki KOBAYASHI
author_facet	Akihiro HAYAKAWA Takashi GOTO Rentaro MIMOTO Taku KUDO Hideaki KOBAYASHI
author_sort	Akihiro HAYAKAWA
title	NO formation/reduction mechanisms of ammonia/air premixed flames at various equivalence ratios and pressures
title_short	NO formation/reduction mechanisms of ammonia/air premixed flames at various equivalence ratios and pressures
title_full	NO formation/reduction mechanisms of ammonia/air premixed flames at various equivalence ratios and pressures
title_fullStr	NO formation/reduction mechanisms of ammonia/air premixed flames at various equivalence ratios and pressures
title_full_unstemmed	NO formation/reduction mechanisms of ammonia/air premixed flames at various equivalence ratios and pressures
title_sort	no formation/reduction mechanisms of ammonia/air premixed flames at various equivalence ratios and pressures
publisher	The Japan Society of Mechanical Engineers
publishDate	2015
url	https://doaj.org/article/9bc403d76a494fa7a3d8a93ed77ff296
work_keys_str_mv	AT akihirohayakawa noformationreductionmechanismsofammoniaairpremixedflamesatvariousequivalenceratiosandpressures AT takashigoto noformationreductionmechanismsofammoniaairpremixedflamesatvariousequivalenceratiosandpressures AT rentaromimoto noformationreductionmechanismsofammoniaairpremixedflamesatvariousequivalenceratiosandpressures AT takukudo noformationreductionmechanismsofammoniaairpremixedflamesatvariousequivalenceratiosandpressures AT hideakikobayashi noformationreductionmechanismsofammoniaairpremixedflamesatvariousequivalenceratiosandpressures
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NO formation/reduction mechanisms of ammonia/air premixed flames at various equivalence ratios and pressures

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