Effect of Channel Diameter on the Combustion and Thermal Behavior of a Hydrogen/Air Premixed Flame in a Swirl Micro-Combustor
Improving the flame stability and thermal behavior of the micro-combustor (MC) are major challenges in microscale combustion. In this paper, the micro combustions of an H<sub>2</sub>/air premixed flame in a swirl MC with various channel diameters (<i>D</i><sub>in</su...
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MDPI AG
2019-10-01
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| Series: | Energies |
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| Online Access: | https://www.mdpi.com/1996-1073/12/20/3821 |
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| author | Xiao Yang Zhihong He Lei Zhao Shikui Dong Heping Tan |
| author_facet | Xiao Yang Zhihong He Lei Zhao Shikui Dong Heping Tan |
| author_sort | Xiao Yang |
| collection | DOAJ |
| description | Improving the flame stability and thermal behavior of the micro-combustor (MC) are major challenges in microscale combustion. In this paper, the micro combustions of an H<sub>2</sub>/air premixed flame in a swirl MC with various channel diameters (<i>D</i><sub>in</sub> = 2, 3, 4 mm) were analyzed based on an established three-dimensional numerical model. The effects of hydrogen mass flow rate, thermal conductivity of walls, and the preferential transport of species were investigated. The results indicated that the flame type was characterized by the presence of two recirculation zones. The flame was anchored by the recirculation zones, and the anchoring location of the flame root was the starting position of the recirculation zones. The recirculation zones had a larger distribution of local equivalence ratio, especially in the proximity of the flame root, indicating the formation of a radical pool. The combustion efficiency increased with an increasing <i>D</i><sub>in</sub> due to the longer residence time of the reactants. Furthermore, the MC with <i>D</i><sub>in</sub> = 2 mm obtained the highest outer wall temperature distribution. However, the MC with <i>D</i><sub>in</sub> = 4 mm had a better uniformity of outer wall temperature and large emitter efficiency due to the larger radiation surface. An increase in thermal conductivity boosts the thermal performance of combustion efficiency, emitter efficiency, and wall temperature uniformity. But there is a critical point of thermal conductivity that can increase the thermal performance. The above results can offer us significant guidance for designing MC with high thermal performance. |
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| id | doaj.art-d819d9c6b7b34f10a853fc5f06635168 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-04-14T05:25:42Z |
| publishDate | 2019-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-d819d9c6b7b34f10a853fc5f066351682022-12-22T02:09:59ZengMDPI AGEnergies1996-10732019-10-011220382110.3390/en12203821en12203821Effect of Channel Diameter on the Combustion and Thermal Behavior of a Hydrogen/Air Premixed Flame in a Swirl Micro-CombustorXiao Yang0Zhihong He1Lei Zhao2Shikui Dong3Heping Tan4Key laboratory of Aerospace Thermophysics, Ministry of Industry and Information Technology, School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, ChinaSchool of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, ChinaKey laboratory of Aerospace Thermophysics, Ministry of Industry and Information Technology, School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, ChinaKey laboratory of Aerospace Thermophysics, Ministry of Industry and Information Technology, School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, ChinaKey laboratory of Aerospace Thermophysics, Ministry of Industry and Information Technology, School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, ChinaImproving the flame stability and thermal behavior of the micro-combustor (MC) are major challenges in microscale combustion. In this paper, the micro combustions of an H<sub>2</sub>/air premixed flame in a swirl MC with various channel diameters (<i>D</i><sub>in</sub> = 2, 3, 4 mm) were analyzed based on an established three-dimensional numerical model. The effects of hydrogen mass flow rate, thermal conductivity of walls, and the preferential transport of species were investigated. The results indicated that the flame type was characterized by the presence of two recirculation zones. The flame was anchored by the recirculation zones, and the anchoring location of the flame root was the starting position of the recirculation zones. The recirculation zones had a larger distribution of local equivalence ratio, especially in the proximity of the flame root, indicating the formation of a radical pool. The combustion efficiency increased with an increasing <i>D</i><sub>in</sub> due to the longer residence time of the reactants. Furthermore, the MC with <i>D</i><sub>in</sub> = 2 mm obtained the highest outer wall temperature distribution. However, the MC with <i>D</i><sub>in</sub> = 4 mm had a better uniformity of outer wall temperature and large emitter efficiency due to the larger radiation surface. An increase in thermal conductivity boosts the thermal performance of combustion efficiency, emitter efficiency, and wall temperature uniformity. But there is a critical point of thermal conductivity that can increase the thermal performance. The above results can offer us significant guidance for designing MC with high thermal performance.https://www.mdpi.com/1996-1073/12/20/3821micro combustionhydrogenswirl micro-combustorchannel diameterflame anchoring |
| spellingShingle | Xiao Yang Zhihong He Lei Zhao Shikui Dong Heping Tan Effect of Channel Diameter on the Combustion and Thermal Behavior of a Hydrogen/Air Premixed Flame in a Swirl Micro-Combustor Energies micro combustion hydrogen swirl micro-combustor channel diameter flame anchoring |
| title | Effect of Channel Diameter on the Combustion and Thermal Behavior of a Hydrogen/Air Premixed Flame in a Swirl Micro-Combustor |
| title_full | Effect of Channel Diameter on the Combustion and Thermal Behavior of a Hydrogen/Air Premixed Flame in a Swirl Micro-Combustor |
| title_fullStr | Effect of Channel Diameter on the Combustion and Thermal Behavior of a Hydrogen/Air Premixed Flame in a Swirl Micro-Combustor |
| title_full_unstemmed | Effect of Channel Diameter on the Combustion and Thermal Behavior of a Hydrogen/Air Premixed Flame in a Swirl Micro-Combustor |
| title_short | Effect of Channel Diameter on the Combustion and Thermal Behavior of a Hydrogen/Air Premixed Flame in a Swirl Micro-Combustor |
| title_sort | effect of channel diameter on the combustion and thermal behavior of a hydrogen air premixed flame in a swirl micro combustor |
| topic | micro combustion hydrogen swirl micro-combustor channel diameter flame anchoring |
| url | https://www.mdpi.com/1996-1073/12/20/3821 |
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