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Low-Temperature Combustion and Cool Flame Dynamics of Multi-Phase Multi-Component Fuels

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Low-Temperature Combustion and Cool Flame Dynamics of Multi-Phase Multi-Component Fuels/ Wenbin Xu.
作者:	Xu, Wenbin,
面頁冊數:	1 electronic resource (122 pages)
附註:	Source: Dissertations Abstracts International, Volume: 87-04, Section: B.
Contained By:	Dissertations Abstracts International87-04B.
標題:	Fluid mechanics. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=32114116
ISBN:	9798293894444

Low-Temperature Combustion and Cool Flame Dynamics of Multi-Phase Multi-Component Fuels
Xu, Wenbin,

Low-Temperature Combustion and Cool Flame Dynamics of Multi-Phase Multi-Component Fuels [electronic resource] /Wenbin Xu. - 1 electronic resource (122 pages)

Source: Dissertations Abstracts International, Volume: 87-04, Section: B.

To improve energy efficiency and reduce greenhouse gas emissions, it is urgent to develop advanced low-temperature combustion engines utilizing carbon-free or low-carbon fuels. Motivated by this objective, this thesis investigates the low-temperature combustion of multi-phase multi-component fuels by focusing on 1) the role of spray dynamics and physics associated with multi-component fuel vaporization in low-temperature autoignition and spray cool flames, and 2) the low-temperature kinetic coupling between ammonia and oxygenated hydrocarbon oxidation.In the first part of the thesis, non-premixed spray cool flames with n-dodecane fuel and n-dodecane/iso-octane fuel blends are established in an atmospheric counterflow burner. A novel phenomenon of repetitive autoignition-extinction instability at near-limit conditions is observed and examined. This instability arises from the timescale competition between low-temperature fuel oxidation and spray vaporization, particularly influenced by the large droplet dynamics. By extending to n-dodecane/iso-octane blended sprays, preferential vaporization effects on flame dynamics and the instability are examined, revealing that the preferentially vaporized iso-octane fuel vapor alters the fuel mixture composition in the reaction zone, weakening the overall low-temperature reactivity. A 1-D two-phase spray combustion model is applied to further quantify the role of droplet dynamics in the spatial distribution of fuel vapor and spray cool flame structures, across a wide range of droplet sizes. The second part of the thesis investigates the dynamics and kinetics of dimethyl-ether (DME)/ammonia (NH3) non-premixed cool and warm flames at elevated pressure. The measured cool flame extinction limits indicate that NH3 kinetics inhibit the DME low-temperature oxidation and thus weaken cool flames. However, NH3 promotes the ignition transition from warm flames to hot flames at low concentrations, while higher levels of NH3 addition delay the ignition transition, leading to either extinction transition into cool flames or complete extinction. Numerical calculations further identify three transition regimes between cool, warm and hot flames. The sensitivity analysis reveals the key kinetic coupling of NH2/NOx/HO2, which results in the non-monotonic effect in the intermediate-temperature range. The research in this thesis provides new insights into the low-temperature combustion and cool flame dynamics of multi-phase multi-component fuels. The investigations of the droplet dynamics and fuel vaporization physics in cool flames and the kinetic interactions between ammonia and oxygenated hydrocarbon fuels will contribute to the development of advanced low-temperature combustion engines.

English

ISBN: 9798293894444Subjects--Topical Terms:

555551
Fluid mechanics.
Subjects--Index Terms:

Ammonia

Low-Temperature Combustion and Cool Flame Dynamics of Multi-Phase Multi-Component Fuels
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520 # $a To improve energy efficiency and reduce greenhouse gas emissions, it is urgent to develop advanced low-temperature combustion engines utilizing carbon-free or low-carbon fuels. Motivated by this objective, this thesis investigates the low-temperature combustion of multi-phase multi-component fuels by focusing on 1) the role of spray dynamics and physics associated with multi-component fuel vaporization in low-temperature autoignition and spray cool flames, and 2) the low-temperature kinetic coupling between ammonia and oxygenated hydrocarbon oxidation.In the first part of the thesis, non-premixed spray cool flames with n-dodecane fuel and n-dodecane/iso-octane fuel blends are established in an atmospheric counterflow burner. A novel phenomenon of repetitive autoignition-extinction instability at near-limit conditions is observed and examined. This instability arises from the timescale competition between low-temperature fuel oxidation and spray vaporization, particularly influenced by the large droplet dynamics. By extending to n-dodecane/iso-octane blended sprays, preferential vaporization effects on flame dynamics and the instability are examined, revealing that the preferentially vaporized iso-octane fuel vapor alters the fuel mixture composition in the reaction zone, weakening the overall low-temperature reactivity. A 1-D two-phase spray combustion model is applied to further quantify the role of droplet dynamics in the spatial distribution of fuel vapor and spray cool flame structures, across a wide range of droplet sizes. The second part of the thesis investigates the dynamics and kinetics of dimethyl-ether (DME)/ammonia (NH3) non-premixed cool and warm flames at elevated pressure. The measured cool flame extinction limits indicate that NH3 kinetics inhibit the DME low-temperature oxidation and thus weaken cool flames. However, NH3 promotes the ignition transition from warm flames to hot flames at low concentrations, while higher levels of NH3 addition delay the ignition transition, leading to either extinction transition into cool flames or complete extinction. Numerical calculations further identify three transition regimes between cool, warm and hot flames. The sensitivity analysis reveals the key kinetic coupling of NH2/NOx/HO2, which results in the non-monotonic effect in the intermediate-temperature range. The research in this thesis provides new insights into the low-temperature combustion and cool flame dynamics of multi-phase multi-component fuels. The investigations of the droplet dynamics and fuel vaporization physics in cool flames and the kinetic interactions between ammonia and oxygenated hydrocarbon fuels will contribute to the development of advanced low-temperature combustion engines.
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650 # 4 $a Aerospace engineering. $3 686400
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653 # # $a Ammonia
653 # # $a Cool flame
653 # # $a Counterflow
653 # # $a Multi-component fuels
653 # # $a Spray combustion
653 # # $a Warm flame
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