| 1. |
- Mannazhi, Manu, et al.
(author)
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Soot Oxidation Studies in an Optical Diesel Engine Using Laser-Induced Incandescence and Extinction : The Effects of Injector Aging and Fuel Additive
- 2021
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In: SAE International Journal of Engines. - : SAE International. - 1946-3936 .- 1946-3944. ; 14:5, s. 749-761
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Journal article (peer-reviewed)abstract
- Previous studies have shown that injector aging adversely affects the diesel engine spray formation and combustion. It has also been shown that the oxygenated fuel additive tripropylene glycol monomethyl ether (TPGME) can lower soot emissions. In this study, the effects of injector aging and TPGME on the late cycle oxidation of soot were investigated using laser diagnostic techniques in a light-duty optical diesel engine at two load conditions. The engine was equipped with a quartz piston with the same complex piston geometry as a production engine. Planar laser-induced incandescence (LII) was used to obtain semiquantitative in-cylinder two-dimensional (2D) soot volume fraction (fv) distributions using extinction measurements. The soot oxidation rate was estimated from the decay rate of the in-cylinder soot concentration for differently aged injectors and for cases with and without TPGME in the fuel. The aged injector produced higher soot concentrations than the new injector at both load conditions. The aged injector also showed higher soot oxidation rates than the new injector at the low load condition. TPGME resulted in lower soot concentrations at both load conditions and faster oxidation rates, especially at mid load conditions.
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| 2. |
- Wang, Shuli, et al.
(author)
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Effects of exhaust gas recirculation at various loads on diesel engine performance and exhaust particle size distribution using four blends with a research octane number of 70 and diesel
- 2017
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In: Energy Conversion and Management. - : Elsevier BV. - 0196-8904. ; 149, s. 918-927
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Journal article (peer-reviewed)abstract
- Partially premixed combustion using gasoline-like fuels on compression ignition engines shows great potentials to break the soot-nitrogen oxides trade off and reduce both emissions simultaneously. By simply adjusting the dilution strategies and injection events, the control of partially premixed combustion is relatively easier compared to other low-temperature combustion concepts. However despite these advantages, recent research shows this concept tends to emit ultra-fine particles. Most previous work on partially premixed combustion only focuses on the soot emissions while the particulate matter in terms of number concentration and size distribution are not well investigated. Ultra-fine particles are dangerous to human health and are getting increasing attentions. Thus the detailed particulate matter emission from partially premixed combustion needs to be further investigated. In this work four gasoline-like ternary fuel blends are designed and experimentally tested under partially premixed combustion. The test blends all share the same two base fuels and blended with different additives. The fuel composition is varied to have the same research octane number. Tests are conducted under different engine loads and dilution strategies since the temperature and oxygen concentration are the key factors in the formation and oxidation of soot. Standard diesel is also tested under the same conditions as a comparison. It is found that these blends are capable of running under partially premixed combustion at low and medium loads and they produce near zero soot emissions when using high exhaust gas recirculation rate. However, these blends do emit smaller particles than diesel under all test loads. Besides, blends with oxygen content yield less soot emissions and smaller particles compared to non-oxygen blends.
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| 3. |
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| 4. |
- Zhu, Xinda, et al.
(author)
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High-Speed Imaging of Spray Formation and Combustion in an Optical Engine : Effects of Injector Aging and TPGME as a Fuel Additive
- 2020
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In: Energies. - : MDPI AG. - 1996-1073. ; 13:12
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Journal article (peer-reviewed)abstract
- High-speed imaging of fuel sprays and combustion is conducted on a light-duty optical engine to investigate the effects of injector aging, with a focus on soot. The spray behaviors of one new and one aged injector are compared using Mie-scattering. In addition to this, the combustion process of a baseline diesel fuel and a blend with TPGME (tripropylene glycol monomethyl ether) are compared using natural luminosity (NL) imaging. TPGME is an oxygenated additive which can be used to reduce soot emissions. X-ray tomography of the two injectors demonstrates that the aging does not lead to significant geometry differences, nor to formation of dense internal nozzle deposits. Both injectors show similar liquid penetration and spreading angle. However, the aged injector shows a prolonged injection and more fuel dribbling after the injection events, leading to a higher injection quantity. The fuel quantity difference shows a larger impact on the NL at low load than the TPGME additive, indicating that the in-cylinder temperature is more important for soot oxidation than oxygen concentration under these conditions. At medium load, the NL is much less sensitive to small temperature variations, while the TPGME is more effective for soot reduction.
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| 5. |
- Zhu, Xinda, et al.
(author)
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Performance of new and aged injectors with and without fuel additives in a light duty diesel engine
- 2020
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In: Transportation Engineering. - : Elsevier BV. - 2666-691X. ; 1
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Journal article (peer-reviewed)abstract
- Two sets of diesel injectors are tested in combination with common fuel additives in a multi-cylinder light-duty diesel engine. One set consists of new injectors and the other is aged by over 100,000 km use in a vehicle. Four fuels are tested with these injector sets to investigate the impact of fuel additives on combustion and emission characteristics. The results show that the aged injectors consistently deliver larger quantities of fuel for a given injection strategy, leading to a higher power output and deviating emissions. This is hypothesized to be due to drift in the injector actuating characteristics. The fuels tested are a baseline diesel quality, and blends of this fuel with three additives: a cetane number improver (2-ethylhexyl nitrate), a soot reducer (tripropylene-glycol monomethyl ether), and a flow improver consisting of quaternary ammonium salts. At the selected low and medium load operating conditions, these additives had a smaller effect on the emissions than the injector ageing, the most notable effect being that TPGME reduces the soot emissions even at the oxygen-rich conditions studied here. These studies will be followed by optical investigations of the in-cylinder effects on spray and combustion characteristics.
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