九州大学 研究者情報
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基本情報 研究活動 教育活動
OKAFOR EKENECHUKWU CHIJIOKE(おかふおー えけねちゆく ちじおけ) データ更新日:2024.01.24

准教授 /  工学研究院 機械工学部門 燃焼科学


主な研究テーマ
旋回流燃焼器におけるアンモニア・水素希薄火炎の排気ガス制御方法解明
キーワード:燃焼、水素、アンモニア、保炎、ガスタービン、エミッション、
2023.04~2025.03.
アンモニア・天然ガス工業炉バーナー研究開発
キーワード:工業炉、バーナー、アンモニア、天然ガス
2022.04.
酸素富化アンモニア火炎の層流及び乱流燃焼速度解明に関する研究
キーワード:アンモニア、酸素富化燃焼、燃焼速度、
2022.04~2023.03.
液体アンモニア噴霧燃焼ガスタービン技術研究開発
キーワード:噴霧燃焼、液体アンモニア、ガスタービン、スワールバーナー、エミッション、
2019.04~2025.09.
アンモニア燃焼反応モデル構築・検証に関する研究
キーワード:燃焼、アンモニア、反応機構、層流燃焼速度
2015.10~2019.03.
旋回流燃焼器におけるアンモニア直接燃焼に関する研究
キーワード:燃焼、アンモニア、保炎、ガスタービン、スワールバーナー、エミッション、
2015.10~2019.03.
球状伝播CH4-H2-空気火炎の層流および乱流燃焼速度に及ぼす圧力および水素濃度の影響に関する研究。
キーワード:燃焼、水素、メタン、燃焼速度、Markstein長さ、Markstein数, 火炎伸長, Lewis数
2010.10~2015.09.
研究業績
主要著書
1. De Vries N.; Okafor E. C.; Woo Y.; Giles A.; Valera-Medina A., Techno-Economic Challenges of Green Ammonia as an Energy Vector; Chapter 7: Applications, 10.1016/B978-0-12-820560-0.00007-2, 2021.10.
2. De Vries N.; Okafor E. C.; Guesta-Bozo M.; Xiao H.; Valera-Medina A., Techno-Economic Challenges of Green Ammonia as Energy Vector; Chapter 6:Use of Ammonia for Heat, Power and Propulsion, Academic Press, 10.1016/B978-0-12-820560-0.00006-0, 2021.10.
主要原著論文
1. Somarathne K.D.K.A, Yamashita H., Colson S., Oku K., Honda K., Okafor E.C., Hayakawa A., Kudo T., Kobayashi H., Towards the development of liquid ammonia/air spray combustion in a gas turbine-like combustor at moderately high pressure, Applications in Energy and Combustion Science, https://doi.org/10.1016/j.jaecs.2023.100215, 16, 100215, 2023.10.
2. Okafor E.C., Yamashita H., Kurata O., Inoue T., Tsujimura T., Iki N., Hayakawa A., Ito S., Uchida M., Kobayashi H., Numerical Investigation of the Diluting Effects of Secondary Air on the Primary Combustion Zone of Two-Stage Rich-Lean Ammonia Gas Turbine Combustors, Proceedings of the 14th Asia-Pacific Conference on Combustion, 2023.05.
3. M. Kovaleva, G.J. Gotama, A. Hayakawa, E.C. Okafor, S. Colson, A. Crayford, T. Kudo, H. Kobayashi, The Impact of Soret Diffusion on the Product Gas Characteristics of Premixed Laminar Ammonia/Hydrogen/Air Flames Stabilised in a Stagnation Flow, Proceedings of the 14th Asia-Pacific Conference on Combustion, 2023.05.
4. Akihiro Hayakawa, Masao Hayashia, Marina Kovaleva, Gabriel J.Gotama, Ekenechukwu C.Okafor, SophieColson, Syed Mashruk, Agustin Valera-Medina, Taku Kudo, Hideaki Kobayashi, Experimental and numerical study of product gas and N2O emission characteristics of ammonia/hydrogen/air premixed laminar flames stabilized in a stagnation flow, Proceedings of the Combustion Institute, https://doi.org/10.1016/j.proci.2022.08.124, 39, 2022.12.
5. Syed Mashruk; Marina Kovaleva; Ali Alnasif; Cheng Tung Chong; Akihiro Hayakawa; Ekenechukwu C.Okafor; AgustinValera-Medina, Nitrogen oxide emissions analyses in ammonia/hydrogen/air premixed swirling flames, Energy, 10.1016/j.energy.2022.125183, 260, 125183, 2022.08.
6. Mashruk S.; Okafor E.C.; Kovaleva M.; Alnasif A.; Pugh D.; Hayakawa A.; Valera-Medina A., Evolution of N2O production at lean combustion condition in NH3/H2/air premixed swirling flames, Combustion and Flame, 10.1016/j.combustflame.2022.112299, 244, 112299, 2022.08.
7. Marina Kovaleva, Akihiro Hayakawa, Sophie Colson, Ekenechukwu C. Okafor, Taku Kudo, Agustin Valera-Medina, Hideaki Kobayashi, Numerical and experimental study of product gas characteristics in premixed ammonia/methane/air laminar flames stabilised in a stagnation flow, Fuel Communications, 10.1016/j.jfueco.2022.100054, 10, 100054-100054, 2022.03.
8. Kanoshima R.; Hayakawa A.; Kudo T.; Okafor E.C.; Colson S.; Ichikawa A.; Kudo T.; Kobayashi H., Effects of initial mixture temperature and pressure on laminar burning velocity and Markstein length of ammonia/air premixed laminar flames, FUEL, 10.1016/j.fuel.2021.122149, 310, B, 2022.02.
9. Gotama G.J.; Hayakawa A.; Okafor E.C.; Kanoshima R.; Hayashi M.; Kudo T.; Kobayashi H., Measurement of the laminar burning velocity and kinetics study of the importance of the hydrogen recovery mechanism of ammonia/hydrogen/air premixed flames, COMBUSTION AND FLAME, 10.1016/j.combustflame.2021.111753, 236, 2022.02.
10. Mashruk S.; Kovaleva M.; Chong C.T.; Hayakawa A.; Okafor E.C.; Valera-Medina A., Nitrogen Oxides as a By-product of Ammonia/Hydrogen Combustion Regimes, CHEMICAL ENGINEERING TRANSACTIONS, 10.3303/CET2189103, 89, 613-618, 2021.12.
11. Okafor E.C., Kurata O., Yamashita H., Inoue T., Tsujimura T., Iki N., Hayakawa A., Ito S., Uchida M., Kobayashi H., On Simultaneous Flame Enhancement and NOx Control in Liquid Ammonia Spray Combustion in a Micro Gas Turbine Combustor, Proceedings of the 13th Asia-Pacific Conference on Combustion, 2021.11.
12. Yamashita H., Hayakawa A., Okafor E.C., Colson S., Somarathne K.D.K.A, Tsujimura T., Ito S., Uchida M., Kudo T., Kobayashi H., Optimum Equivalence Ratio for Low NO and Unburned NH3 Emissions in Gaseous Ammonia Flames Co-fired with Methane or Hydrogen in a Swirling Flow, Proceedings of the 13th Asia-Pacific Conference on Combustion, 2021.12.
13. Hayakawa A., Hayashi M., Gotama G.J., Kovaleva M., Okafor E.C., Colson S., Kudo T., Mashruk S., Valera-Medina A., Kobayashi H.,, N2O Production Characteristics of Ammonia/Hydrogen/Air Premixed Laminar Flames Stabilized in Stagnation Flows at Lean Conditions, Proceedings of the 13th Asia-Pacific Conference on Combustion, 2021.11.
14. Somarathne K.D.K.A, Yamashita H., Colson S., Okafor E.C., Hayakawa A., Kudo T., Kobayashi H., Liquid Ammonia Spray Combustion and Emission Characteristics with Gaseous Hydrogen/air Co-firing, Proceedings of the 13th Asia-Pacific Conference on Combustion, 2021.11.
15. Okafor E.C.; Kurata O.; Yamashita H.; Inoue T.; Tsujimura T.; Iki N.; Hayakawa A.; Ito S.; Uchida M.; Kobayashi H., Liquid Ammonia Spray Combustion in Two-Stage Micro Gas Turbine Combustors at 0.25 MPa; Relevance of Combustion Enhancement to Flame Stability and NOx Control, APPLICATIONS IN ENERGY AND COMBUSTION SCIENCE, 10.1016/j.jaecs.2021.100038, 7, 2021.09.
16. Kurata, O., Iki, N., Fan, Y., Matsunuma, T., Inoue, T., Tsujimura, T., Furutani, H., Kawano, M., Arai, K., Okafor, E. C., Hayakawa, A., Kobayashi, H, Start-up process of 50kW-class gas turbine firing ammonia gas, Proceedings of ASME Turbo Expo 2021:Turbomachinery Technical Conference and Exposition, 10.1115/GT2021-59448, 2021.06.
17. Ekenechukwu C. Okafor, Hirofumi Yamashita, Akihiro Hayakawa, K. D. Kunkuma A. Somarathne, Taku Kudo, Taku Tsujimura, Masahiro Uchida, Shintaro Ito, Hideaki Kobayashi, Flame stability and emissions characteristics of liquid ammonia spray co-fired with methane in a single stage swirl combustor, FUEL, 10.1016/j.fuel.2020.119433, 287, 2020.10.
18. Okafor Ekenechukwu C .; Tsukamoto Masaaki; Hayakawa Akihiro; Somarathne KD Kunkuma A .; Kudo Taku; Tsujimura Taku; Kobayashi Hideaki, Influence of wall heat loss on the emission characteristics of premixed ammonia-air swirling flames interacting with the combustor wall, PROCEEDINGS OF THE COMBUSTION INSTITUTE, 10.1016/j.proci.2020.06.142, 38, 4, 5139-5146, 2021.01.
19. Hayakawa Akihiro; Hirano Yuta; Okafor Ekenechukwu C.; Yamashita Hirofumi; Kudo Taku; Kobayashi Hideaki, Experimental and numerical study of product gas characteristics of ammonia/air premixed laminar flames stabilized in a stagnation flow, PROCEEDINGS OF THE COMBUSTION INSTITUTE, 10.1016/j.proci.2020.07.030, 38, 2, 2409-2417, 2021.01.
20. Somarathne Kapuruge Don Kunkuma Amila; Okafor Ekenechukwu C .; Sugawara Daiki; Hayakawa Akihiro; Kobayashi Hideaki, Effects of OH concentration and temperature on NO emission characteristics of turbulent non-premixed CH4/NH3/air flames in a two-stage gas turbine like combustor at high pressure, PROCEEDINGS OF THE COMBUSTION INSTITUTE, 10.1016/j.proci.2020.06.276, 38, 4, 5163-5170, 2021.01.
21. Willyanto Anggono, Akihiro Hayakawa, Ekenechukwu C. Okafor, Gabriel Jeremy Gotama, Stevan Wongso, Laminar Burning Velocity and Markstein Length of CH4/CO2/Air Premixed Flames at Various Equivalence Ratios and CO2 Concentrations Under Elevated Pressure, COMBUSTION SCIENCE AND TECHNOLOGY, 10.1080/00102202.2020.1737032, 2020.03.
22. Okafor Ekenechukwu C .; Somarathne KD Kunkuma A .; Ratthanan Rattanasupapornsak; Hayakawa Akihiro; Kudo Taku; Kurata Osamu; Iki Norihiko; Tsujimura Taku; Furutani Hirohide; Kobayashi Hideaki, Control of NOx and other emissions in micro gas turbine combustors fuelled with mixtures of methane and ammonia, COMBUSTION AND FLAME, 10.1016/j.combustflame.2019.10.012, 211, 406-416, 2020.01.
23. Somarathne Kapuruge Don Kunkuma Amila; Okafor Ekenechukwu C.; Hayakawa Akihiro; Kudo Taku; Kurata Osamu; Iki Norihiko; Kobayashi Hideaki, Emission characteristics of turbulent non-premixed ammonia/air and methane/air swirl flames through a rich-lean combustor under various wall thermal boundary conditions at high pressure, COMBUSTION AND FLAME, 10.1016/j.combustflame.2019.08.037, 210, 247-261, 2019.12.
24. Okafor Ekenechukwu C.; Naito Yuji; Colson Sophie; Ichikawa Akinori; Kudo Taku; Hayakawa Akihiro; Kobayashi Hideaki, Measurement and modelling of the laminar burning velocity of methane-ammonia-air flames at high pressures using a reduced reaction mechanism, COMBUSTION AND FLAME, 10.1016/j.combustflame.2019.03.008, 204, 162-175, 2019.06.
25. Hayakawa, A. Hirano, Y., Okafor, E.C., Kudo, T., Kobayashi, H., Product Gas Characteristics of Strain Stabilized Ammonia/air Premixed Laminar Flames, Proceedings of the 12th Asia-Pacific Conference on Combustion, 2019.07.
26. Somarathne, K.D.K.A., Okafor, E.C., Hayakawa, A., Kobayashi, H., Emission Characteristics of Turbulent Non-premixed CH4/NH3/air Swirl Flames through a Rich-Lean Gas Turbine-like Combustor at High Pressure, Proceedings of the 12th Asia-Pacific Conference on Combustion, 2019.07.
27. Okafor, E.C., Rattanasupapornsak, R., Somarathne, K.D.K.A., Hayakawa, A., Kudo, T., Kurata, O, Iki, N, Tsujimura, T., Kobayashi, H., On the control of NOx emission from a micro gas turbine combustor fueled with mixtures of methane and ammonia, Proceedings of the 12th Asia-Pacific Conference on Combustion, 2019.07.
28. Iki, N., Kurata, O., Inoue, T., Matsunuma, T., Tsujimuira, T., Furutani, H., Kawano, M., Arai, K., Kobayashi, H., Hayakawa, A., Okafor, E. C., Rich-lean combustor for a 50kW class micro gas turbine firing ammonia, Proceedings of Global Power and Propulsion Society, 2019.06, [URL].
29. Okafor Ekenechukwu C .; Somarathne KD Kunkuma A .; Hayakawa Akihiro; Kudo Taku; Kurata Osamu; Iki Norihiko; Kobayashi Hideaki, Towards the development of an efficient low-NOx ammonia combustor for a micro gas turbine, PROCEEDINGS OF THE COMBUSTION INSTITUTE, 10.1016/j.proci.2018.07.083, 37, 4, 4597-4606, 2019.01.
30. Kobayashi Hideaki; Hayakawa Akihiro; Somarathne KD Kunkuma A .; Okafor Ekenechukwu C., Science and technology of ammonia combustion, PROCEEDINGS OF THE COMBUSTION INSTITUTE, 10.1016/j.proci.2018.09.029, 37, 1, 109-133, 2019.01.
31. Kurata Osamu; Iki Norihiko; Inoue Takahiro; Matsunuma Takayuki; Tsujimura Taku; Furutani Hirohide; Kawano Masato; Arai Keisuke; Okafor Ekenechukwu Chijioke; Hayakawa Akihiro; Kobayashi Hideaki, Development of a wide range-operable, rich-lean low-NOx combustor for NH3 fuel gas-turbine power generation, PROCEEDINGS OF THE COMBUSTION INSTITUTE, 10.1016/j.proci.2018.09.012, 37, 4, 4587-4595, 2019.01.
32. Okafor Ekenechukwu C .; Naito Yuji; Colson Sophie; Ichikawa Akinori; Kudo Taku; Hayakawa Akihiro; Kobayashi Hideaki, Experimental and numerical study of the laminar burning velocity of CH4-NH3-air premixed flames, COMBUSTION AND FLAME, 10.1016/j.combustflame.2017.09.002, 187, 185-198, 2018.01.
33. Iki, N., Kurata, O., Inoue, T., Matsunuma, T., Tsujimuira, T., Furutani, H., Kobayashi, H., Hayakawa, A., Okafor, E. C., NOx reduction of a swirl combustor firing ammonia for a micro gas turbine, Proceedings of ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, 10.1115/GT2018-75993, 2018.08.
34. Okafor, E.C., Sakai, K., Akihiro, H., Kudo, T., Kurata, O, Iki, N, Kobayashi, H., Stabilization and emission characteristics of ammonia flames in a micro gas turbine combustor, Proceedings of the 11th Asia-Pacific Conference on Combustion, 2017.12.
35. Okafor Ekenechukwu C .; Nagano Yukihide; Kitagawa Toshiaki, Experimental and theoretical analysis of cellular instability in lean H-2-CH4-air flames at elevated pressures, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, 10.1016/j.ijhydene.2016.02.151, 41, 15, 6581-6592, 2016.04.
36. Ekenechukwu C. Okafor, Akihiro Hayakawa, Yukihide Nagano, Toshiaki Kitagawa, Effects of hydrogen concentration on premixed laminar flames of hydrogen-methane-air, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, 10.1016/j.ijhydene.2013.11.128, 39, 5, 2409-2417, 2014.02.
37. Ekenechukwu C. Okafor, Yosuke Fukuda, Yukihide Nagano, Toshiaki Kitagawa, Turbulent Burning Velocities of Stoichiometric Hydrogen-Carbon Monoxide-Air Flames at Elevated Pressures, SAE Technical Papers, 10.4271/2014-01-2701, 2014-October, 2014.10.
38. Okafor, E.C., Nagano, Y., Kitagawa T., Effects of hydrogen concentration on stoichiometric H2/CH4/Air premixed turbulent flames, SAE/KSAE Powertrain Fuel and Lubricants Meeting, doi.org/10.4271/2013-01-2563, 2013.10.
39. Okafor, E.C., Toyoda, M., Hayakawa, A., Nagano, Y., Kitagawa, T., Experimental and numerical studies on burning velocities and Markstein numbers of lean laminar H2/CH4/air flames, Proceedings of the 9th Asia-Pacific Conference on Combustion, 2013.07.
主要総説, 論評, 解説, 書評, 報告書等
主要学会発表等
学会活動
所属学会名
日本機械学会
日本ガスタービン学会
Combustion Institute
日本燃焼学会
学会大会・会議・シンポジウム等における役割
2021.01~2021.01, 38th International Symposium on Combustion , Session Chairman.
2023.05.14~2023.05.18, 14th Asia-Pacific Conference on Combustion , Session Chairman.
2023.12.05~2023.12.07, 第34回内燃機関シンポジウム, 幹事.
学会誌・雑誌・著書の編集への参加状況
2021.06, Journal of Thermal Science, 国際, 査読委員.
2020.06~2020.07, Combustion Science and Technology, 国際, 査読委員.
2020.02~2020.04, IEEE Access, 国際, 査読委員.
2017.01, Fuel, 国際, 査読委員.
2018.03, International Journal of Chemical Reactor Engineering, 国際, 査読委員.
2019.03, International Journal of Energy Research, 国際, 査読委員.
2018.01, Energy and Fuels, 国際, 査読委員.
2019.01, Proceedings of the Combustion Institute, 国際, 査読委員.
2017.10, International Journal of Hydrogen Energy, 国際, 査読委員.
2019.01, Combustion and Flame, 国際, 査読委員.
学術論文等の審査
年度 外国語雑誌査読論文数 日本語雑誌査読論文数 国際会議録査読論文数 国内会議録査読論文数 合計
2023年度     14 
2022年度 12      15 
受賞
2023年度 日本燃焼学会 論文賞, 日本燃焼学会, 2023.11.
ASPACC 2021 Young Investigator Award, Asia-Pacific section of the Combustion Institute, 2021.12.
2021年 日本燃焼学会 奨励賞, 日本燃焼学会, 2021.11.
2020年度 日本燃焼学会 論文賞, 日本燃焼学会, 2020.12.
2019年度 日本燃焼学会 論文賞, 日本燃焼学会, 2019.11.
Best Poster and Presentation Award, Kyushu University/KAIST, 2014.09.
Excellence in Oral Presentation, Society of Automotive Engineers, 2013.10.
Best Science Student Award, University of Nigeria Secondary School Nsukka, University of Nigeria Secondary School, Nsukka, 2001.09.
Best Graduating Student Award, University of Nigeria Secondary School Nsukka, University of Nigeria Secondary School, Nsukka, 2001.09.
研究資金
科学研究費補助金の採択状況(文部科学省、日本学術振興会)
2023年度~2024年度, 若手研究, 代表, Investigation of a novel lean-lean two-stage combustion strategy for the control of NOx from swirl combustors fueled with mixtures of ammonia and hydrogen..

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