High Octane Number Fuels in Advanced Combustion Modes for Sustainable Transportation
(2020)- Abstract
- The research community recently proposed a low-temperature combustion (LTC) concept that can simultaneously reduce Nitrogen Oxides (NOx) and soot emissions while maintaining high engine efficiency. Given that diesel fuel is prone to preignition with early injection, gasoline-like fuel with high octane number is utilised to provide sufficient ignition delay and extend the load range. Understanding the influence of high-octane fuel on ignition delay is a key parameter to achieve higher loads in LTC. However, understanding is still lacking on the combustion characteristics of high-octane fuel under LTC in real engines, and the effect of fuel spray–piston interaction is not fully understood. Despite the extended load limits offered by... (More)
- The research community recently proposed a low-temperature combustion (LTC) concept that can simultaneously reduce Nitrogen Oxides (NOx) and soot emissions while maintaining high engine efficiency. Given that diesel fuel is prone to preignition with early injection, gasoline-like fuel with high octane number is utilised to provide sufficient ignition delay and extend the load range. Understanding the influence of high-octane fuel on ignition delay is a key parameter to achieve higher loads in LTC. However, understanding is still lacking on the combustion characteristics of high-octane fuel under LTC in real engines, and the effect of fuel spray–piston interaction is not fully understood. Despite the extended load limits offered by high-octane fuels, they require energy-intensive production during the refinery processes, a condition that raises an issue with well-to-wheel carbon dioxide (CO2). To mitigate the issue of CO2 emission, research proposed methanol as a high-octane renewable fuel.
This thesis focuses on assessing the impact of higher-octane number fuels in LTC under a low load condition. To achieve this objective, the work was divided into two parts. The first part was devoted to evaluating the required ignition delay of high-octane fuels and explaining the effect of fuel spray–piston interactions. In this work, the fuels were evaluated under similar operating conditions in a light-duty multi-cylinder engine. The experimental results revealed a linear correlation between octane number and required ignition delay for lower octane fuels. However, an exponential correlation was observed for higher number octane fuel because of the fuel spray–piston geometry interaction.
The second part aimed to evaluate the effect of injection strategies and air dilution on methanol combustion in a heavy-duty engine. A comparison was performed between methanol and isooctane (primary reference fuel, PRF100) under injection timing sweep. Methanol was then compared at two intake pressures. Later, double and triple injection strategies with different mass proportions and dwells were performed on methanol under the partially premixed combustion. Additionally, numerical simulations were used to interpret the experimental results. The results revealed that the φ-stratification of methanol is less sensitive to the injection timing compared to that of PRF100. Soot emission was always low for methanol and insensitive to injection timing, compare to PRF100. When the intake pressure was increased, the mixture became globally lean, resulting in a lower NOx and unburned hydrocarbon (UHC) but a minor penalty on carbon monoxide (CO) emission. The gross indicated efficiency of methanol was improved at the later injection timing for the boosted case.
Subsequently, when compared with single injection, the double injection strategy with lower pilot mass and shorter pilot-main dwell showed an effective strategy to simultaneously reduce UHC and CO emissions and increase engine efficiency at the expense of a minor rise in NOx emission. Interestingly, the results demonstrated that the triple injection strategy was capable of achieving similar engine efficiency as the single and double injection strategies. Although a minor rise in CO emission occurred, the triple injection strategy demonstrated its potential to significantly decrease NOx and UHC emissions compared to other strategies. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/36d51b09-d87b-43d5-b7a2-5abf30495ac6
- author
- Bin Aziz, Amir LU
- supervisor
- opponent
-
- Prof. Foucher, Fabrice, University of Orléans, France.
- organization
- publishing date
- 2020-10-26
- type
- Thesis
- publication status
- published
- subject
- keywords
- Octane number, Low temperature combustion (LTC), Ignition delay, Methanol, HCCI, PPC, Multiple injection strategy, φ-stratification
- pages
- 174 pages
- publisher
- Energy Sciences, Lund University
- defense location
- Lecture hall KC:A, Kemicentrum, Naturvetarvägen 14, Faculty of Engineering LTH, Lund University, Lund.
- defense date
- 2020-11-19 10:15:00
- ISBN
- 978-91-7895-662-3
- 978-91-7895-663-0
- language
- English
- LU publication?
- yes
- id
- 36d51b09-d87b-43d5-b7a2-5abf30495ac6
- date added to LUP
- 2020-10-27 10:06:48
- date last changed
- 2020-12-01 12:57:15
@phdthesis{36d51b09-d87b-43d5-b7a2-5abf30495ac6,
abstract = {{The research community recently proposed a low-temperature combustion (LTC) concept that can simultaneously reduce Nitrogen Oxides (NOx) and soot emissions while maintaining high engine efficiency. Given that diesel fuel is prone to preignition with early injection, gasoline-like fuel with high octane number is utilised to provide sufficient ignition delay and extend the load range. Understanding the influence of high-octane fuel on ignition delay is a key parameter to achieve higher loads in LTC. However, understanding is still lacking on the combustion characteristics of high-octane fuel under LTC in real engines, and the effect of fuel spray–piston interaction is not fully understood. Despite the extended load limits offered by high-octane fuels, they require energy-intensive production during the refinery processes, a condition that raises an issue with well-to-wheel carbon dioxide (CO2). To mitigate the issue of CO2 emission, research proposed methanol as a high-octane renewable fuel. <br/>This thesis focuses on assessing the impact of higher-octane number fuels in LTC under a low load condition. To achieve this objective, the work was divided into two parts. The first part was devoted to evaluating the required ignition delay of high-octane fuels and explaining the effect of fuel spray–piston interactions. In this work, the fuels were evaluated under similar operating conditions in a light-duty multi-cylinder engine. The experimental results revealed a linear correlation between octane number and required ignition delay for lower octane fuels. However, an exponential correlation was observed for higher number octane fuel because of the fuel spray–piston geometry interaction. <br/>The second part aimed to evaluate the effect of injection strategies and air dilution on methanol combustion in a heavy-duty engine. A comparison was performed between methanol and isooctane (primary reference fuel, PRF100) under injection timing sweep. Methanol was then compared at two intake pressures. Later, double and triple injection strategies with different mass proportions and dwells were performed on methanol under the partially premixed combustion. Additionally, numerical simulations were used to interpret the experimental results. The results revealed that the φ-stratification of methanol is less sensitive to the injection timing compared to that of PRF100. Soot emission was always low for methanol and insensitive to injection timing, compare to PRF100. When the intake pressure was increased, the mixture became globally lean, resulting in a lower NOx and unburned hydrocarbon (UHC) but a minor penalty on carbon monoxide (CO) emission. The gross indicated efficiency of methanol was improved at the later injection timing for the boosted case. <br/>Subsequently, when compared with single injection, the double injection strategy with lower pilot mass and shorter pilot-main dwell showed an effective strategy to simultaneously reduce UHC and CO emissions and increase engine efficiency at the expense of a minor rise in NOx emission. Interestingly, the results demonstrated that the triple injection strategy was capable of achieving similar engine efficiency as the single and double injection strategies. Although a minor rise in CO emission occurred, the triple injection strategy demonstrated its potential to significantly decrease NOx and UHC emissions compared to other strategies.}},
author = {{Bin Aziz, Amir}},
isbn = {{978-91-7895-662-3}},
keywords = {{Octane number; Low temperature combustion (LTC); Ignition delay; Methanol; HCCI; PPC; Multiple injection strategy; φ-stratification}},
language = {{eng}},
month = {{10}},
publisher = {{Energy Sciences, Lund University}},
school = {{Lund University}},
title = {{High Octane Number Fuels in Advanced Combustion Modes for Sustainable Transportation}},
url = {{https://lup.lub.lu.se/search/files/85852725/Amir_Aziz_PhDThesis.pdf}},
year = {{2020}},
}