| Ekenechukwu Chijioke Okafor | Last modified dateļ¼2024.04.26 |
Associate Professor /
Combusiton Science /
Department of Mechanical Engineering /
Faculty of Engineering
Papers
| 1. | Hirofumi Yamashita, Akihiro Hayakawa, Ekenechukwu C. Okafor, Sophie Colson, K. D. Kunkuma A. Somarathne, Taku Tsujimura, Shintaro Ito, Masahiro Uchida, Taku Kudo, Hideaki Kobayashi, Optimum primary equivalence ratio for rich-lean two-stage combustion of non-premixed ammonia/methane/air and ammonia/hydrogen/air flames in a swirling flow, Fuel, https://doi.org/10.1016/j.fuel.2024.131598, 368, 131598, 2024.04, [URL]. |
| 2. | 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. |
| 3. | 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. |
| 4. | 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. |
| 5. | 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. |
| 6. | 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. |
| 7. | 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. |
| 8. | 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. |
| 9. | 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. |
| 10. | 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. |
| 11. | 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. |
| 12. | 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. |
| 13. | 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. |
| 14. | 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. |
| 15. | 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. |
| 16. | 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. |
| 17. | 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. |
| 18. | 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. |
| 19. | 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. |
| 20. | 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. |
| 21. | 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. |
| 22. | 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. |
| 23. | 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. |
| 24. | 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. |
| 25. | 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. |
| 26. | 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. |
| 27. | 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. |
| 28. | 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. |
| 29. | 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]. |
| 30. | 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. |
| 31. | 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. |
| 32. | 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. |
| 33. | 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. |
| 34. | 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. |
| 35. | 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. |
| 36. | 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. |
| 37. | 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. |
| 38. | 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. |
| 39. | 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. |
| 40. | 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. |
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