Experimental Studies on Fuel Effects in Dual-Fuel Combustion

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Journal Title
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Volume Title
School of Engineering | Doctoral thesis (article-based) | Defence date: 2022-04-22
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Author
Date
2022
Department
Konetekniikan laitos
Department of Mechanical Engineering
Major/Subject
Mcode
Degree programme
Language
en
Pages
76 + app. 86
Series
Aalto University publication series DOCTORAL THESES, 51/2022
Abstract
The present dissertation belongs to the research field of experimental physics and emissions reduction from a heavy-duty engine. Various alternative fuels such as diesel-like liquid fuels, methane, ethane, hydrogen, and methanol are employed in a single-cylinder research engine to experimentally investigate their combustion characteristics at varying engine conditions. Dual-fuel (DF) combustion is the focal point in this dissertation in which port-injected low reactivity fuel is ignited by a diesel-pilot directly injected close to the top-dead center. The research includes optical study and engine experiments, which aim at extending the fundamental understanding of DF ignition and subsequent combustion progression, improving engine efficiency, performance, and reducing engine-out emissions. DF combustion is a promising engine combustion technology for adopting various fuels, however, there are still operational limitations that need further improvements to meet future clean-energy goals in transportation. The present dissertation consists of 5 journal publications. Four of them investigate primarily the use of methane and one is focusing on methanol DF combustion. Publication 1 investigates diesel-methane DF ignition and progression of subsequent combustion in an optical engine using high-speed imaging of natural luminosity. Publication 2 investigates the effects of pilot fuel properties on DF ignition, engine performance, and engine-out emissions. Publications 3 and 4 study ethane/hydrogen enriched methane DF combustion to improve combustion efficiency, stability, and engine performance at lean conditions. Publication 5 investigates methanol DF combustion with negative valve overlap (NVO) to attain high engine efficiency together with ultra-low pollutant emissions at wide range of engine operating loads. The main findings of this dissertation can be summarized as follows: 1) In diesel-methane DF combustion, premixed flames grow and propagate towards the center of the chamber and at high equivalence ratios, flame propagation is more prominent. The ignition delay time is found to be a function of methane equivalence ratio, charge-air temperature, and pilot-diesel amount. In addition, DF combustion progresses as three overlapping stages with premixed combustion as a dominant mechanism. 2) For small pilot quantities, in general, a higher cetane number fuel with higher aromatic content improves DF combustion. Additionally, high viscosity, density, and distillation temperatures avoid possible leaning out of a pilot spray within methane-air mixture. 3) Ethane or hydrogen enrichment improves the reactivity of pure methane and helps to extend the range of lean operability and attain high thermal efficiency (>50%). 4) It is found that methanol DF combustion under NVO mode can produce high efficiency (>50%) with ultra-low emissions at wide range of engine operating loads.
Description
Supervising professor
Larmi, Martti, Prof., Aalto University, Department of Mechanical Engineering, Finland
Thesis advisor
Kaario, Ossi, Dr., Aalto University, Finland
Keywords
CI engine, dual fuel combustion, alternative fuels, efficiency, exhaust emissions
Other note
Parts
  • [Publication 1]: Ahmad Zeeshan, Kaario Ossi, Cheng Qiang, Vuorinen Ville, Larmi Martti. A parametric investigation of diesel/methane dual-fuel combustion progression/stages in a heavy-duty optical engine. Applied Energy (2019), volume 251, pages 113191.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-201906203942
    DOI: 10.1016/j.apenergy.2019.04.187 View at publisher
  • [Publication 2]: Ahmad Zeeshan, Kaario Ossi, Cheng Qiang, Larmi Martti. Effect of pilot fuel properties on lean dual-fuel combustion and emission characteristics in a heavy-duty engine. Applied Energy (2020), volume 282, part A, pages 116134.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-2020113020617
    DOI: 10.1016/j.apenergy.2020.116134 View at publisher
  • [Publication 3]: Ahmad Zeeshan, Kaario Ossi, Karimkashi Shervin, Cheng Qiang, Vuorinen Ville, Larmi Martti. Effects of ethane addition on diesel-methane dual-fuel combustion in a heavy-duty engine. Fuel (2021), volume 289, pages 119834.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-202101251600
    DOI: 10.1016/j.fuel.2020.119834 View at publisher
  • [Publication 4]: Cheng Qiang, Ahmad Zeeshan, Kaario Ossi, Vuorinen Ville, Larmi Martti. Experimental study on tri-fuel combustion using premixed methane-hydrogen mixtures ignited by a diesel pilot. International Journal of Hydrogen Energy (2021), volume 46, issue 40, pages 21182-21197.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-202107017856
    DOI: 10.1016/j.ijhydene.2021.03.215 View at publisher
  • [Publication 5]: Ahmad Zeeshan, Kaario Ossi, Cheng Qiang, Larmi Martti. Effect of negative valve overlap in a heavy-duty methanol-diesel dual-fuel engine: a pathway to improve efficiency. Fuel (2022), volume 317, pages 123522.
    Full text in Acris/Aaltodoc: http://urn.fi/URN:NBN:fi:aalto-202203032096
    DOI: 10.1016/j.fuel.2022.123522 View at publisher
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https://urn.fi/URN:ISBN:978-952-64-0764-7
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[diss] Insinööritieteiden korkeakoulu / ENG