Review of Pre-Ignition Research in Methanol Engines

Methanol can be synthesized using green electricity and carbon dioxide, making it a green, carbon-neutral fuel with significant potential for widespread application in engines. However, due to its low ignition energy and high laminar flame speed, methanol is susceptible to hotspot-induced pre-igniti...

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Main Authors: Zhijie Li, Changhui Zhai, Xiaoxiao Zeng, Kui Shi, Xinbo Wu, Tianwei Ma, Yunliang Qi
Format: Article
Language:English
Published: MDPI AG 2024-12-01
Series:Energies
Subjects:
Online Access:https://www.mdpi.com/1996-1073/18/1/133
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author Zhijie Li
Changhui Zhai
Xiaoxiao Zeng
Kui Shi
Xinbo Wu
Tianwei Ma
Yunliang Qi
author_facet Zhijie Li
Changhui Zhai
Xiaoxiao Zeng
Kui Shi
Xinbo Wu
Tianwei Ma
Yunliang Qi
author_sort Zhijie Li
collection DOAJ
description Methanol can be synthesized using green electricity and carbon dioxide, making it a green, carbon-neutral fuel with significant potential for widespread application in engines. However, due to its low ignition energy and high laminar flame speed, methanol is susceptible to hotspot-induced pre-ignition and even knocking under high-temperature, high-load engine conditions, posing challenges to engine performance and reliability. This paper systematically reviews the manifestations and mechanisms of pre-ignition and knocking in methanol engines. Pre-ignition can be sustained or sporadic. Sustained pre-ignition is caused by overheating of structural components, while sporadic pre-ignition is often linked to oil droplets entering the combustion chamber from the piston crevice. Residual exhaust gas trapped within the spark plug can also initiate pre-ignition. Knocking, characterized by pressure oscillations, arises from the auto-ignition of hotspots in the end-gas or, potentially, from deflagration-to-detonation transition, although the latter requires further experimental validation. Factors influencing pre-ignition and knocking, including engine oil, in-cylinder deposits, structural hotspots, and the reactivity of the air–fuel mixture, are also analyzed. Based on these factors, the paper concludes that the primary approach to suppressing pre-ignition and knocking in methanol engines is controlling the formation of pre-ignition sources and reducing the reactivity of the air–fuel mixture. Furthermore, it addresses existing issues and limitations in current research, such as combustion testing techniques, numerical simulation accuracy, and the mechanisms of methanol–oil interaction, and offers related recommendations.
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spelling doaj-art-567170c3b1b64edab7cca4f5bb9c74e22025-01-10T13:17:11ZengMDPI AGEnergies1996-10732024-12-0118113310.3390/en18010133Review of Pre-Ignition Research in Methanol EnginesZhijie Li0Changhui Zhai1Xiaoxiao Zeng2Kui Shi3Xinbo Wu4Tianwei Ma5Yunliang Qi6Weichai Power Co., Ltd., Weifang 261061, ChinaWeichai Power Co., Ltd., Weifang 261061, ChinaWeichai Power Co., Ltd., Weifang 261061, ChinaWeichai Power Co., Ltd., Weifang 261061, ChinaWeichai Power Co., Ltd., Weifang 261061, ChinaWeichai Power Co., Ltd., Weifang 261061, ChinaSchool of Vehicle and Mobility, Tsinghua University, Beijing 100084, ChinaMethanol can be synthesized using green electricity and carbon dioxide, making it a green, carbon-neutral fuel with significant potential for widespread application in engines. However, due to its low ignition energy and high laminar flame speed, methanol is susceptible to hotspot-induced pre-ignition and even knocking under high-temperature, high-load engine conditions, posing challenges to engine performance and reliability. This paper systematically reviews the manifestations and mechanisms of pre-ignition and knocking in methanol engines. Pre-ignition can be sustained or sporadic. Sustained pre-ignition is caused by overheating of structural components, while sporadic pre-ignition is often linked to oil droplets entering the combustion chamber from the piston crevice. Residual exhaust gas trapped within the spark plug can also initiate pre-ignition. Knocking, characterized by pressure oscillations, arises from the auto-ignition of hotspots in the end-gas or, potentially, from deflagration-to-detonation transition, although the latter requires further experimental validation. Factors influencing pre-ignition and knocking, including engine oil, in-cylinder deposits, structural hotspots, and the reactivity of the air–fuel mixture, are also analyzed. Based on these factors, the paper concludes that the primary approach to suppressing pre-ignition and knocking in methanol engines is controlling the formation of pre-ignition sources and reducing the reactivity of the air–fuel mixture. Furthermore, it addresses existing issues and limitations in current research, such as combustion testing techniques, numerical simulation accuracy, and the mechanisms of methanol–oil interaction, and offers related recommendations.https://www.mdpi.com/1996-1073/18/1/133methanolinternal combustion enginepre-ignitionoil
spellingShingle Zhijie Li
Changhui Zhai
Xiaoxiao Zeng
Kui Shi
Xinbo Wu
Tianwei Ma
Yunliang Qi
Review of Pre-Ignition Research in Methanol Engines
Energies
methanol
internal combustion engine
pre-ignition
oil
title Review of Pre-Ignition Research in Methanol Engines
title_full Review of Pre-Ignition Research in Methanol Engines
title_fullStr Review of Pre-Ignition Research in Methanol Engines
title_full_unstemmed Review of Pre-Ignition Research in Methanol Engines
title_short Review of Pre-Ignition Research in Methanol Engines
title_sort review of pre ignition research in methanol engines
topic methanol
internal combustion engine
pre-ignition
oil
url https://www.mdpi.com/1996-1073/18/1/133
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AT kuishi reviewofpreignitionresearchinmethanolengines
AT xinbowu reviewofpreignitionresearchinmethanolengines
AT tianweima reviewofpreignitionresearchinmethanolengines
AT yunliangqi reviewofpreignitionresearchinmethanolengines