+publisher:"University of New South Wales" +contributor:("Kook, Sanghoon, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW")

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University of New South Wales

1. Rusly, Alvin Mulianto. The transiency of in-cylinder flame development in an automotive-size diesel engine.

Degree: Mechanical & Manufacturing Engineering, 2013, University of New South Wales

URL: http://handle.unsw.edu.au/1959.4/52828 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:11501/SOURCE01?view=true

► Global growth in the sales of light-duty diesel-powered vehicles is effectively driven by diesel engines superior fuel economy though concerns implicating emission formations and usage… (more)

▼ Global growth in the sales of light-duty diesel-powered vehicles is effectively driven by diesel engines superior fuel economy though concerns implicating emission formations and usage of non-renewable fossil still persist. Such obstacles present a need for better understanding of the diesel combustion, which will help improve engine efficiency and reduce pollutant emissions. To address this issue, experimental study of in-cylinder combustion processes is conducted in a light-duty diesel engine with focus on flame development transience. A new experimental research facility has been designed and constructed to study transient behaviour of diesel flames during combustion. The facility houses a modified single-cylinder diesel engine that allows optical access to the combustion chamber at realistic engine environment and ambient conditions. Two distinctly different diesel combustion regimes are investigated: one with short injection duration and the other with long injection duration. The first of the combustion regimes consists of short injection duration and long ignition delay ultimately resulting in a positive ignition dwell (fuel injection completes prior to ignition). In this regime, the overall combustion is dominated by premixed burn phase whereby further improvement of efficiency is limited by a drastic increase in in-cylinder pressure. If the problem is severe, undesirable pressure ringing follows the initial pressure rise, which is called diesel knock. The first part of this thesis addresses this issue of knocking in a light-duty diesel engine. In the optical engine, high-speed natural hot soot luminosity imaging was performed to visualise flame behaviour during the knocking cycles. It is found that the diesel flame oscillates against the normal swirl direction and the oscillation frequency matches the frequency of in-cylinder pressure ringing, which is the first observation of such correspondence in a diesel engine. Experimentation with pilot injection showed a remedial effect through elimination of pressure ringing and dampening of flame oscillation. Such results are connected with a short ignition delay and less intense premixed combustion as shown through a lower pressure rise rate and negative ignition dwell (i.e. mixing-controlled combustion).The second regime investigated in this thesis presents long injection duration through a single-hole injector resulting in a negative ignition dwell (combustion starts prior to the end of injection). This regime is dominated by mixing-controlled combustion phase corresponding to high-load engine operating conditions. Opposed to the short-injection regime with positive ignition dwell, this long-injection regime is characterised by a lifted flame that is under the strong influence of jet-wall interaction during and after the fuel injection. Therefore, the focus of last half of this thesis is on the jet-wall interaction and its impact on lift-off length (i.e. distance between the nozzle to the first detectable flame base within a specified spatial range with respect… Advisors/Committee Members: Kook, Sanghoon, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW, Hawkes, Evatt R., Photovoltaics & Renewable Energy Engineering, Faculty of Engineering, UNSW.

Subjects/Keywords: Re-entrainment; Diesel; Knock; Lift-off Length; Optical Engine

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APA (6^th Edition):

Rusly, A. M. (2013). The transiency of in-cylinder flame development in an automotive-size diesel engine. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/52828 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:11501/SOURCE01?view=true

Chicago Manual of Style (16^th Edition):

Rusly, Alvin Mulianto. “The transiency of in-cylinder flame development in an automotive-size diesel engine.” 2013. Doctoral Dissertation, University of New South Wales. Accessed April 13, 2021. http://handle.unsw.edu.au/1959.4/52828 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:11501/SOURCE01?view=true.

MLA Handbook (7^th Edition):

Rusly, Alvin Mulianto. “The transiency of in-cylinder flame development in an automotive-size diesel engine.” 2013. Web. 13 Apr 2021.

Vancouver:

Rusly AM. The transiency of in-cylinder flame development in an automotive-size diesel engine. [Internet] [Doctoral dissertation]. University of New South Wales; 2013. [cited 2021 Apr 13]. Available from: http://handle.unsw.edu.au/1959.4/52828 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:11501/SOURCE01?view=true.

Council of Science Editors:

Rusly AM. The transiency of in-cylinder flame development in an automotive-size diesel engine. [Doctoral Dissertation]. University of New South Wales; 2013. Available from: http://handle.unsw.edu.au/1959.4/52828 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:11501/SOURCE01?view=true

University of New South Wales

2. Padala, Srinivas. Ethanol port injection and dual-fuel combustion in a common-rail diesel engine.

Degree: Mechanical & Manufacturing Engineering, 2013, University of New South Wales

URL: http://handle.unsw.edu.au/1959.4/52880 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:11558/SOURCE01?view=true

► Opposed to a conventional approach of using ethanol in a spark-ignition engine, this study demonstrates a potential of ethanol utilization in a diesel engine using… (more)

▼ Opposed to a conventional approach of using ethanol in a spark-ignition engine, this study demonstrates a potential of ethanol utilization in a diesel engine using dual-fuel combustion strategy where ethanol is injected into the intake manifold and diesel is directly injected into the combustion chamber. The main focus of this study is the effect of ethanol port fuel injector (PFI) sprays on dual-fuel combustion and emissions. Firstly, details of temporal and spatial development of ethanol PFI sprays were studied using Mie-scattering and high-speed shadowgraph imaging techniques. Momentum flux-based injection rate measurement was also performed. The influences of fuel flow-rate, injection duration, and ambient air cross-flow are of particular interest in an effort to understand ethanol PFI spray characteristics that are relevant to automobile engines. Ethanol sprays are also studied for various PFI positions to examine the potential effect of droplets-airflow interaction and wall wetting. With the clear understanding on ethanol PFI sprays, dual-fuel engine experiments were conducted for various ethanol energy ratios and PFI positions. It is found that the effect of PFI position on global phenomena such as in-cylinder pressure, apparent heat release rate and mean effective pressure is much less significant than the effect of ethanol energy fraction. However, the misfiring limit shows measurable difference such that the PFI position closer to the intake valves results in 10% higher ethanol energy fraction than that of the further upstream position. Reduced wall-wetting due to surface boiling occurring on the hot valve seat is suggested as a possible cause, which is consistent with 30% lower carbon monoxide and 64% lower unburnt hydrocarbon emissions. Detailed investigation for various ethanol energy fractions was also conducted. From the in-cylinder pressure measurements, it is found that the increased ethanol energy fraction increases the engine efficiency up to 10% until it is limited by misfiring. The results are compared to diesel-only operation with varying injection timings in order to explain whether the increased efficiency is due to the combustion phasing or improved combustion associated with fast burning of ethanol. Further analysis of the data reveals that the latter is the primary cause for the efficiency gain. By advancing the diesel injection timing, it is found that the maximum ethanol fraction can be extended to 70% without the misfiring problem but 20% increase in nitrogen oxide emissions is also observed, which raises a question on the advantages of utilizing ethanol in a diesel engine. However, negligible smoke emissions are measured at ethanol energy ratio of 20% or higher suggesting that optimization of these emissions is much easier compared with conventional diesel combustion. Advisors/Committee Members: Kook, Sanghoon, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW, Hawkes, Evatt, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW.

Subjects/Keywords: Port fuel injecton; Ethanol; Dual fuelling; Diesel

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APA (6^th Edition):

Padala, S. (2013). Ethanol port injection and dual-fuel combustion in a common-rail diesel engine. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/52880 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:11558/SOURCE01?view=true

Chicago Manual of Style (16^th Edition):

Padala, Srinivas. “Ethanol port injection and dual-fuel combustion in a common-rail diesel engine.” 2013. Doctoral Dissertation, University of New South Wales. Accessed April 13, 2021. http://handle.unsw.edu.au/1959.4/52880 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:11558/SOURCE01?view=true.

MLA Handbook (7^th Edition):

Padala, Srinivas. “Ethanol port injection and dual-fuel combustion in a common-rail diesel engine.” 2013. Web. 13 Apr 2021.

Vancouver:

Padala S. Ethanol port injection and dual-fuel combustion in a common-rail diesel engine. [Internet] [Doctoral dissertation]. University of New South Wales; 2013. [cited 2021 Apr 13]. Available from: http://handle.unsw.edu.au/1959.4/52880 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:11558/SOURCE01?view=true.

Council of Science Editors:

Padala S. Ethanol port injection and dual-fuel combustion in a common-rail diesel engine. [Doctoral Dissertation]. University of New South Wales; 2013. Available from: http://handle.unsw.edu.au/1959.4/52880 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:11558/SOURCE01?view=true

University of New South Wales

3. Bao, Yongming. Effect of injection pressure on ethanol and gasoline sprays in a spark-ignition direct-injection engine.

Degree: Mechanical & Manufacturing Engineering, 2013, University of New South Wales

URL: http://handle.unsw.edu.au/1959.4/53399 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12094/SOURCE02?view=true

► This study aims to clarify the spray development of ethanol, gasoline and iso-octane fuel, delivered by a multi-hole injector and spark-ignition direct-injection (SIDI) fuelling system.… (more)

▼ This study aims to clarify the spray development of ethanol, gasoline and iso-octane fuel, delivered by a multi-hole injector and spark-ignition direct-injection (SIDI) fuelling system. The focus is on how fuel properties and injection pressure impact temporal and spatial evolution of sprays at various ambient conditions. Two optical facilities were used: (1) a constant-flow spray chamber simulating cold-start conditions and (2) a single-cylinder SIDI engine running at normal, warmed-up operating conditions. In these optical facilities, Mie-scattering imaging is performed to measure penetrations of spray plumes at various injection pressures of 4, 7, 11 and 15 MPa. Experiments were first performed in the spray chamber to measure the spray tip penetration and penetration rate of ethanol, gasoline and iso-octane. It is observed that at 4 MPa injection pressure, the tip penetration length of ethanol sprays is shorter than that of gasoline sprays, likely due to lower injection velocity and increased nozzle loss associated with higher density and increased viscosity of ethanol, respectively. This assertion is further supported by the longest penetration length of iso-octane that has the lowest density among tested fuels and similar viscosity to gasoline. At higher injection pressure of 7 and 11 MPa, the penetration length difference between ethanol and gasoline sprays decreases and eventually ethanol sprays show a longer penetration length than that of gasoline sprays at the highest injection pressure of 15 MPa. This reversed trend is possibly because the penetration regime is changed such that the tip penetration is limited by aerodynamic drag force applied to fuel droplets, instead of the injection velocity or nozzle loss of the liquid jet. It is suggested that with increasing injection pressure, the fuel jet atomisation and droplet breakup enhance and therefore the lower aerodynamic drag associated with higher droplet size of ethanol sprays than that of gasoline sprays leads to a longer penetration length. The same trends of spray penetrations of ethanol, gasoline, and iso-octane are observed in the warmed optical engine with overall higher tip penetration length than that in the cold spray chamber primarily due to decreased air density and increased fuel temperature. In the same warmed optical engine, the effect of injection pressure on the structural transformation of flash-boiling sprays of gasoline and ethanol is investigated for two fuel injection timings of 90 and 300 crank angle degrees after top dead centre, corresponding to low and high ambient pressure conditions, respectively. The macroscopic spray structure was quantified using spray tip penetrations, spray spreading angles and spray areas. From the measurements, it is found that fuel sprays injected at the earlier injection timing, when the vapour pressure of the fuel is higher than the ambient pressure, show the convergence of the spray plumes towards the injector axis evidencing the flash-boiling phenomenon. By contrast, fuel injected at the later… Advisors/Committee Members: Kook, Sanghoon, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW.

Subjects/Keywords: Ethanol; Gasoline; Iso-octane fuel; Spark-ignition direct-injection (SIDI); Injection pressure; Spray; Fuel economy

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APA (6^th Edition):

Bao, Y. (2013). Effect of injection pressure on ethanol and gasoline sprays in a spark-ignition direct-injection engine. (Masters Thesis). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/53399 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12094/SOURCE02?view=true

Chicago Manual of Style (16^th Edition):

Bao, Yongming. “Effect of injection pressure on ethanol and gasoline sprays in a spark-ignition direct-injection engine.” 2013. Masters Thesis, University of New South Wales. Accessed April 13, 2021. http://handle.unsw.edu.au/1959.4/53399 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12094/SOURCE02?view=true.

MLA Handbook (7^th Edition):

Bao, Yongming. “Effect of injection pressure on ethanol and gasoline sprays in a spark-ignition direct-injection engine.” 2013. Web. 13 Apr 2021.

Vancouver:

Bao Y. Effect of injection pressure on ethanol and gasoline sprays in a spark-ignition direct-injection engine. [Internet] [Masters thesis]. University of New South Wales; 2013. [cited 2021 Apr 13]. Available from: http://handle.unsw.edu.au/1959.4/53399 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12094/SOURCE02?view=true.

Council of Science Editors:

Bao Y. Effect of injection pressure on ethanol and gasoline sprays in a spark-ignition direct-injection engine. [Masters Thesis]. University of New South Wales; 2013. Available from: http://handle.unsw.edu.au/1959.4/53399 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12094/SOURCE02?view=true

University of New South Wales

4. Zhang, Haoyang. Modelling of stratified charge compression ignition engines.

Degree: Photovoltaics & Renewable Energy Engineering, 2014, University of New South Wales

URL: http://handle.unsw.edu.au/1959.4/53630 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12325/SOURCE02?view=true

► Homogeneous charge compression-ignition (HCCI) engines have been considered to hold potential for next generation internal combustion engines with low emissions and low fuel-consumption. However, some… (more)

▼ Homogeneous charge compression-ignition (HCCI) engines have been considered to hold potential for next generation internal combustion engines with low emissions and low fuel-consumption. However, some technical hurdles, such as low combustion-efficiency at low load and excessive pressure-rise rate (PRR) at high load, significantly challenge its practical application.In this thesis, fundamental studies of fuel ignition response to thermal stratification were first conducted by using direct numerical simulations coupled with a detailed chemistry mechanism. For a two-stage ignition fuel with negative temperature coefficient (NTC) behaviour, dimethyl ether, the auto-ignition regime was found to depend strongly on the initial temperature. Molecular diffusion was found to be negligible in comparison to chemical reaction when the initial temperature fell inside NTC regime; however, once the initial temperature was outside NTC regime, diffusion became relatively more significant. Diffusion was also observed to decrease with an increase of the length-scale. PRR was found to be reduced with thermal stratification, but this was also dependent on the mean temperature.Then, non-reacting multi-dimensional engine modelling was conducted to investigate the effects of fuel direct injection on the resulting mixture distribution. It was found that as the start of injection was retarded, more fuel was concentrated in the central areas of the cylinder, leading to a potential increase of combustion efficiency and potential reduction of carbon monoxide and unburned hydrocarbons, but a potential increase of excessive nitrogen oxides. Droplet-wall interaction and spray-to-spray interaction were observed to play essential roles in fuel distribution. Furthermore, the use of high injection pressure can enhance the mixing, while the use of high swirl ratio and low injection pressure showed negative effects on the global mixing.Finally, reacting engine simulations were carried on to study the effects of thermal stratification on a fully premixed HCCI engine fuelled by ethanol. These studies pointed out many challenges with attempts to model HCCI predictively, owing to strong sensitivities to initial charge temperature and pressure, wall temperatures, residual gas composition, initial turbulence intensity and models for its evolution and wall models. These sensitivities were analysed and used to construct an optimised model that agreed quite well with experimental pressure traces and associated quantities such as the PRR, the indicated mean effective pressure, and the thermal efficiency. Analysis of the optimised model results was used to determine that enhanced thermal stratification demonstrated a significant reduction of the PRR. The degree of the reduction was found to depend on the penetration of thermal stratification into the bulk-gas regions. In addition, turbulence played an important role in the control combustion phasing primarily by altering the distributions of thermal stratification. Advisors/Committee Members: Hawkes, Evatt, Photovoltaics & Renewable Energy Engineering, Faculty of Engineering, UNSW, Kook, Sanghoon, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW.

Subjects/Keywords: CFD; HCCI; SCCI; Autoignition; Direct injection

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APA (6^th Edition):

Zhang, H. (2014). Modelling of stratified charge compression ignition engines. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/53630 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12325/SOURCE02?view=true

Chicago Manual of Style (16^th Edition):

Zhang, Haoyang. “Modelling of stratified charge compression ignition engines.” 2014. Doctoral Dissertation, University of New South Wales. Accessed April 13, 2021. http://handle.unsw.edu.au/1959.4/53630 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12325/SOURCE02?view=true.

MLA Handbook (7^th Edition):

Zhang, Haoyang. “Modelling of stratified charge compression ignition engines.” 2014. Web. 13 Apr 2021.

Vancouver:

Zhang H. Modelling of stratified charge compression ignition engines. [Internet] [Doctoral dissertation]. University of New South Wales; 2014. [cited 2021 Apr 13]. Available from: http://handle.unsw.edu.au/1959.4/53630 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12325/SOURCE02?view=true.

Council of Science Editors:

Zhang H. Modelling of stratified charge compression ignition engines. [Doctoral Dissertation]. University of New South Wales; 2014. Available from: http://handle.unsw.edu.au/1959.4/53630 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12325/SOURCE02?view=true

University of New South Wales

5. Zhang, Renlin. Soot Particle Sampling and Morphology Analysis in an Optically Accessible Diesel Engine.

Degree: Mechanical & Manufacturing Engineering, 2014, University of New South Wales

URL: http://handle.unsw.edu.au/1959.4/54002 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12710/SOURCE02?view=true

► A significant reduction of soot emissions from diesel engines cannot be achieved without an improved understanding of the soot processes inside the engine cylinder. While… (more)

▼ A significant reduction of soot emissions from diesel engines cannot be achieved without an improved understanding of the soot processes inside the engine cylinder. While previous studies have primarily focused on exhaust soot particles, how these soot particles are formed in the first place is virtually unknown. To bridge this gap, this thesis presents a new experimental approach for collecting soot particles inside the cylinder of a single-cylinder light-duty diesel engine using a thermophoretic sampling technique. Soot samples are analysed using transmission electron microscopy (TEM) and subsequent image post-processing to obtain key parameters such as size distributions and fractal dimensions of soot particles. Results of this thesis demonstrate the successful collection of in-flame soot particles for the first time in a working diesel engine. The uncertainty analysis showed that the cyclic dispersions of engine combustion do not inflict significant impacts on particle size distribution. Parametrical studies with various injection timing and pressure revealed that the late injection timing or high injection pressure reduces the number counts, projection area, aggregate size and fractal dimension of in-flame soot particles. Increasing injection pressure also resulted in reduced primary particle size. Soot samplings were also conducted for various combustion stages by changing the sampling location with respect to the diesel flame. Reduced soot projection area and aggregate size are found for post-wall-impingement soot particles suggesting the effect of flame-wall interaction. Furthermore, late-cycle and exhaust soot particles show reduced number counts, projection area, and primary particle size. These trends suggest that small particles are easily oxidized during the combustion while large aggregates with compact structures would more likely survive the oxidation. Moreover, the wall-deposited and in-flame soot particles were compared. The results show much smaller number counts, projection area and more compacted structures for the wall-deposited soot particles. The findings of this study are expected to build a new science base needed by industry to develop improved combustion strategies that achieve further reduction in soot emissions. The data provided by this work would also help build new soot models applicable to practical diesel engine conditions. Advisors/Committee Members: Kook, Sanghoon, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW, Hawkes, Evatt, Photovoltaics & Renewable Energy Engineering, Faculty of Engineering, UNSW.

Subjects/Keywords: Soot emissions; Particles; Diesel engines; Thermophoretic sampling technique; Transmission electron microscopy (TEM); Engine cylinder; Cyclic dispersion; Engine combustion

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APA (6^th Edition):

Zhang, R. (2014). Soot Particle Sampling and Morphology Analysis in an Optically Accessible Diesel Engine. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/54002 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12710/SOURCE02?view=true

Chicago Manual of Style (16^th Edition):

Zhang, Renlin. “Soot Particle Sampling and Morphology Analysis in an Optically Accessible Diesel Engine.” 2014. Doctoral Dissertation, University of New South Wales. Accessed April 13, 2021. http://handle.unsw.edu.au/1959.4/54002 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12710/SOURCE02?view=true.

MLA Handbook (7^th Edition):

Zhang, Renlin. “Soot Particle Sampling and Morphology Analysis in an Optically Accessible Diesel Engine.” 2014. Web. 13 Apr 2021.

Vancouver:

Zhang R. Soot Particle Sampling and Morphology Analysis in an Optically Accessible Diesel Engine. [Internet] [Doctoral dissertation]. University of New South Wales; 2014. [cited 2021 Apr 13]. Available from: http://handle.unsw.edu.au/1959.4/54002 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12710/SOURCE02?view=true.

Council of Science Editors:

Zhang R. Soot Particle Sampling and Morphology Analysis in an Optically Accessible Diesel Engine. [Doctoral Dissertation]. University of New South Wales; 2014. Available from: http://handle.unsw.edu.au/1959.4/54002 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12710/SOURCE02?view=true

University of New South Wales

6. Liu, Xinyu. Influence of Triple Injection Strategy, Exhaust Gas Recirculation and E-boosting on Performance and Emissions in a Gasoline Compression Ignition (GCI) Engine.

Degree: Mechanical & Manufacturing Engineering, 2019, University of New South Wales

URL: http://handle.unsw.edu.au/1959.4/69725 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:71286/SOURCE02?view=true

► Gasoline compression ignition (GCI) engines promise a significant reduction in NOx and smoke emissions while maintaining high efficiency of diesel engines. This thesis implemented triple… (more)

▼ Gasoline compression ignition (GCI) engines promise a significant reduction in NOx and smoke emissions while maintaining high efficiency of diesel engines. This thesis implemented triple injection strategy, exhaust gas recirculation (EGR) and intake air e-boosting with an aim to further improve GCI combustion. The engine performance and emissions results obtained from a single-cylinder common-rail diesel engine were analysed with a specific interest in how each of these key parameters impacts the in-cylinder pressure, heat release rate, combustion phasing, efficiency and engine-out emissions. From the systematic tests of triple injection strategy, GCI combustion showed high sensitivity to the second/third injection proportion and timing. Increased charge premixing and advanced combustion phasing was found with increased 2nd injection proportion or advanced 3rd injection timing placed at mid-to-late crank angle and near-TDC, respectively. However, the increased in-cylinder pressure and apparent heat release rate (aHRR) resulted in higher NOx emissions. This was resolved using advanced 2nd injection timing, which led to higher mixture homogeneity and thus lower peak in-cylinder pressure and aHRR for decreased NOx, smoke and noise emissions. To further reduce NOx emissions, EGR was tested in the 0 to 16% range. In consideration of lower power output with the use of EGR, a supercharger driven by an electric motor (i.e. e-booster) was also used for up to 130 kPa (absolute) intake air pressure. The results indicated that higher EGR ratio causes reduced in-cylinder pressure and aHRR to achieve significant NOx and noise emissions reduction. However, it suffered from reduced engine efficiency and increased smoke/uHC/CO emissions. This was recovered using e-boosting due to higher intake air pressure and thus reduced pumping loss and increased in-cylinder pressure. At the same time, the reduced ignition delay time caused lower peak aHRR, which in turn further reduced NOx emissions. The resulting NOx reduction due to the combined use of EGR and e-boosting was very significant as the e-boosting successfully reduced uHC and CO emissions back to no EGR level. Advisors/Committee Members: Kook, Sanghoon, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW, Hawkes, Evatt, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW.

Subjects/Keywords: Exhaust gas recirculation; Gasoline compression ignition; Triple injection strategy; intake air e-boosting

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Liu, X. (2019). Influence of Triple Injection Strategy, Exhaust Gas Recirculation and E-boosting on Performance and Emissions in a Gasoline Compression Ignition (GCI) Engine. (Masters Thesis). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/69725 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:71286/SOURCE02?view=true

Chicago Manual of Style (16^th Edition):

Liu, Xinyu. “Influence of Triple Injection Strategy, Exhaust Gas Recirculation and E-boosting on Performance and Emissions in a Gasoline Compression Ignition (GCI) Engine.” 2019. Masters Thesis, University of New South Wales. Accessed April 13, 2021. http://handle.unsw.edu.au/1959.4/69725 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:71286/SOURCE02?view=true.

MLA Handbook (7^th Edition):

Vancouver:

Liu X. Influence of Triple Injection Strategy, Exhaust Gas Recirculation and E-boosting on Performance and Emissions in a Gasoline Compression Ignition (GCI) Engine. [Internet] [Masters thesis]. University of New South Wales; 2019. [cited 2021 Apr 13]. Available from: http://handle.unsw.edu.au/1959.4/69725 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:71286/SOURCE02?view=true.

Council of Science Editors:

Liu X. Influence of Triple Injection Strategy, Exhaust Gas Recirculation and E-boosting on Performance and Emissions in a Gasoline Compression Ignition (GCI) Engine. [Masters Thesis]. University of New South Wales; 2019. Available from: http://handle.unsw.edu.au/1959.4/69725 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:71286/SOURCE02?view=true

University of New South Wales

7. Le, Minh Khoi. Understanding the development of a reacting fuel jet inside an automotive-size diesel engine using optical and laser-based diagnostics.

Degree: Mechanical & Manufacturing Engineering, 2015, University of New South Wales

URL: http://handle.unsw.edu.au/1959.4/55272 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:37004/SOURCE02?view=true

► The fuel penetration and reacting diesel jet development have been studied in a small-bore optical engine to improve the understanding of a swirl-influenced, wall-interacting diesel… (more)

▼ The fuel penetration and reacting diesel jet development have been studied in a small-bore optical engine to improve the understanding of a swirl-influenced, wall-interacting diesel flame. The optical access to the engine combustion chamber was made possible via multiple quartz windows positioned in a cylindrical piston bowl and cylinder liner. Using the common-rail fuel injection system of the engine, the fuel injection was executed for long duration, creating negative ignition dwell conditions in which the start of combustion occurs before the end of injection. A single-hole nozzle was used to isolate the jet-wall interaction from jet-jet interactions while limiting the in-cylinder pressure below the burst-pressure of quartz windows. Planar laser-induced fluorescence imaging of hydroxyl (OH-PLIF), fuel-PLIF, and line-of-sight integrated chemiluminescence imaging were performed for various combustion stages identified by the in-cylinder pressure traces and apparent heat release rates. These include stages of vaporising fuel penetration, low-temperature reaction, and high-temperature reaction. The fuel-PLIF images show that the fuel penetration was strongly influenced by a swirl flow with the wall-jet penetration on the up-swirl side being shorter than that of the down-swirl jet. During the low-temperature reaction, cool flame chemiluminescence appears in the wall-jet head region. Interestingly, this region is where a turbulent ring-vortex is formed due to jet-wall interactions, suggesting that locally enhanced mixing induced the first-stage ignition. The OH-PLIF images show that the second-stage, high-temperature reaction starts to occur and then expand drastically in the same wall-jet head region. Since the reaction occurs in the wall-jet region, the swirl flow impacts the high-temperature reaction significantly, as evidenced by more intense OH signals in the down-swirl jet. This is due to the influence of the swirl flow on the mixing process, leading to relatively richer mixtures on the down-swirl side. Upon the end of fuel injection, the heat release rate declines and the OH-PLIF signals slowly diminish.How the variation in injection pressure influences the combustion processes of a wall-interacting diesel jet has also been investigated. The cool-flame images together with the apparent heat release rate suggest that the low-temperature reaction still emerges from the wall-interacting jet head region but it becomes stronger with increasing injection pressure due to the better air-fuel mixing at the enhanced turbulent ring-vortex. The influence of in-cylinder swirl flow on the OH* chemiluminescence signals was again observed such that the high-temperature reaction in the down-swirl side of the jet occurs earlier than that in the up-swirl side of the jet regardless of the injection pressure. Moreover, the second-stage ignition on the down-swirl side of the jet is also found to be stronger than the up-swirl side of the jet initially. However, as the injection pressure increases and the high temperature reaction… Advisors/Committee Members: Kook, Sanghoon, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW.

Subjects/Keywords: Laser diagnostics; Optical engine; Engine combustion; OH-PLIF; Soot-PLII; Optical diagnostics; Diesel engine; Diesel jet development

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APA (6^th Edition):

Le, M. K. (2015). Understanding the development of a reacting fuel jet inside an automotive-size diesel engine using optical and laser-based diagnostics. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/55272 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:37004/SOURCE02?view=true

Chicago Manual of Style (16^th Edition):

Le, Minh Khoi. “Understanding the development of a reacting fuel jet inside an automotive-size diesel engine using optical and laser-based diagnostics.” 2015. Doctoral Dissertation, University of New South Wales. Accessed April 13, 2021. http://handle.unsw.edu.au/1959.4/55272 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:37004/SOURCE02?view=true.

MLA Handbook (7^th Edition):

Le, Minh Khoi. “Understanding the development of a reacting fuel jet inside an automotive-size diesel engine using optical and laser-based diagnostics.” 2015. Web. 13 Apr 2021.

Vancouver:

Le MK. Understanding the development of a reacting fuel jet inside an automotive-size diesel engine using optical and laser-based diagnostics. [Internet] [Doctoral dissertation]. University of New South Wales; 2015. [cited 2021 Apr 13]. Available from: http://handle.unsw.edu.au/1959.4/55272 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:37004/SOURCE02?view=true.

Council of Science Editors:

Le MK. Understanding the development of a reacting fuel jet inside an automotive-size diesel engine using optical and laser-based diagnostics. [Doctoral Dissertation]. University of New South Wales; 2015. Available from: http://handle.unsw.edu.au/1959.4/55272 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:37004/SOURCE02?view=true

University of New South Wales

8. Krisman, Alexander. Direct numerical simulation of diesel-relevant combustion.

Degree: Mechanical & Manufacturing Engineering, 2016, University of New South Wales

URL: http://handle.unsw.edu.au/1959.4/55498 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:37862/SOURCE02?view=true

► Diesel combustion is a major contributor to global energy production. However, despite major improvements to diesel engine design, substantial gaps exist in the fundamental description… (more)

▼ Diesel combustion is a major contributor to global energy production. However, despite major improvements to diesel engine design, substantial gaps exist in the fundamental description of the in-cylinder combustion process. This impedes the development of simple, predictive models which are necessary for designing improved combustion devices. In particular, only an under-resolved description of ignition and lifted flame stabilisation exists, due to physical limitations of experimental measurements. Ignition and flame stabilisation govern the formation of pollutants and combustion efficiency, and so a refined understanding is required. In this thesis, direct numerical simulation (DNS) techniques are applied to idealised configurations that represent facets of diesel combustion. A particular focus is applied to representing the correct thermochemical conditions which result in multi-stage autoignition and a negative temperature coefficient (NTC) regime of ignition delay times. The results were broadly consistent with prior experimental studies, but the well-resolved information also revealed details of several novel combustion features that have not been previously reported. Simulations of lifted laminar flames at NTC conditions with detailed dimethyl ether chemistry observed that edge flame or hybrid edge flame/autoignition structures can exist even at diesel-relevant autoignitive conditions, which raises the possibility that edge flame propagation or a combination of edge flame propagation and autoignition are responsible for diesel flame stabilisation. The ignition of a two-dimensional mixing layer at NTC conditions in isotropic turbulence with detailed dimethyl ether chemistry was conducted. A complex ignition process was observed in which two-stage autoignition, cool flames, and hybrid edge flame/autoignition structures contributed to the overall ignition process. In particular, it was observed that the cool flame influenced the timing and location of the high temperature ignition. A three-dimensional ignition at NTC conditions with global heptane chemistry was conducted. The results were consistent with the two-dimensional mixing layer results. The results also emphasised the importance of mixing rates in determining the location and timing of high temperature ignition. Overall, this thesis complements prior experimental results, identifies novel combustion features and highlights the substantial modelling challenge presented by diesel combustion. Advisors/Committee Members: Hawkes, Evatt, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW, Kook, Sanghoon, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW.

Subjects/Keywords: Negative temperature coefficient; Direct numerical simulation; Diesel-relevant combustion; Triple flame; Two-stage ignition; Polybrachial flame; Tribrachial flame; Ignition; Cool flame; Edge flame

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APA (6^th Edition):

Krisman, A. (2016). Direct numerical simulation of diesel-relevant combustion. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/55498 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:37862/SOURCE02?view=true

Chicago Manual of Style (16^th Edition):

Krisman, Alexander. “Direct numerical simulation of diesel-relevant combustion.” 2016. Doctoral Dissertation, University of New South Wales. Accessed April 13, 2021. http://handle.unsw.edu.au/1959.4/55498 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:37862/SOURCE02?view=true.

MLA Handbook (7^th Edition):

Krisman, Alexander. “Direct numerical simulation of diesel-relevant combustion.” 2016. Web. 13 Apr 2021.

Vancouver:

Krisman A. Direct numerical simulation of diesel-relevant combustion. [Internet] [Doctoral dissertation]. University of New South Wales; 2016. [cited 2021 Apr 13]. Available from: http://handle.unsw.edu.au/1959.4/55498 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:37862/SOURCE02?view=true.

Council of Science Editors:

Krisman A. Direct numerical simulation of diesel-relevant combustion. [Doctoral Dissertation]. University of New South Wales; 2016. Available from: http://handle.unsw.edu.au/1959.4/55498 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:37862/SOURCE02?view=true

University of New South Wales

9. Zhang, Yilong. Nanostructure Analysis of In-flame Soot Particles in a Diesel Engine.

Degree: Mechanical & Manufacturing Engineering, 2017, University of New South Wales

URL: http://handle.unsw.edu.au/1959.4/59629 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:49162/SOURCE02?view=true

► Soot particles emitted from modern diesel engines, despite significantly lower total mass, show higher reactivity and toxicity than black-smoking old engines, which cause serious health… (more)

▼ Soot particles emitted from modern diesel engines, despite significantly lower total mass, show higher reactivity and toxicity than black-smoking old engines, which cause serious health and environmental issues. Soot nanostructure, i.e. the internal structure of soot particles composed of nanoscale carbon fringes, can provide useful information to the investigation of the particle reactivity and its oxidation status. This thesis presents the nanostructure details of soot particles sampled directly from diesel flames in a working diesel engine as well as from exhaust gases to compare the internal structure of soot particles in the high formation stage and after in-cylinder oxidation. Thermophoretic soot sampling was conducted using an in-house-designed probe with a lacy transmission electron microscope (TEM) grid stored at the tip. The soot particles deposited on the grid were imaged using a high-resolution TEM to obtain key nanostructure parameters such as carbon fringe length, tortuosity and fringe-to-fringe separation. The TEM images show that in-flame soot particles are consisted of multiple amorphous cores with many defective carbon fringes, which are surrounded by a more oriented and graphitised outer shell. The same core-shell structures are found in the exhaust soot particles, suggesting the overall shape developed within the diesel flame does not change during soot oxidation. However, the exhaust soot particles exhibit more oxidised and less reactive nanostructures as evidenced by the increased fringe length, reduced fringe tortuosity, and lower fringe separation distance. In investigating the in-cylinder particles, the effect of jet-jet interaction on soot nanostructure was considered as one of the major factors. This is because a wall-jet head merging with a neighbouring jet head, which always occurs in diesel engines, is well known to cause high soot formation due to locally rich mixtures. This topic was investigated by performing nanostructure analysis and corresponding morphology analysis of soot particles together with the assistance of planar laser-induced fluorescence of fuel and hydroxyl (fuel- and OH-PLIF) and incandescence of soot (soot-PLII). Since a conventional diesel flame produces a large amount of soot leading to significant beam attenuation to laser diagnostics, methyl decanoate was selected as a surrogate fuel due to its low-sooting propensity. Prior to investigate the effect of jet-jet interaction on soot particles, a direct comparison in soot nanostructure and corresponding morphology is conducted between methyl decanoate and conventional diesel in single jet configuration. The results show that methyl decanoate generates smaller soot primary particles and aggregates with lower fractal dimension, which could be explained either by the earlier stage of soot formation or more oxidised soot status. From the fringe separation results showing a smaller gap for methyl decanoate, it is concluded that the sampled in-flame soot particles were more oxidised likely due to the presence of oxidisers… Advisors/Committee Members: Kook, Sanghoon, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW, Hawkes, Evatt, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW.

Subjects/Keywords: Soot nanostructure; Diesel engine; In-flame soot sampling; Soot morphology; TEM

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Zhang, Y. (2017). Nanostructure Analysis of In-flame Soot Particles in a Diesel Engine. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/59629 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:49162/SOURCE02?view=true

Chicago Manual of Style (16^th Edition):

Zhang, Yilong. “Nanostructure Analysis of In-flame Soot Particles in a Diesel Engine.” 2017. Doctoral Dissertation, University of New South Wales. Accessed April 13, 2021. http://handle.unsw.edu.au/1959.4/59629 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:49162/SOURCE02?view=true.

MLA Handbook (7^th Edition):

Zhang, Yilong. “Nanostructure Analysis of In-flame Soot Particles in a Diesel Engine.” 2017. Web. 13 Apr 2021.

Vancouver:

Zhang Y. Nanostructure Analysis of In-flame Soot Particles in a Diesel Engine. [Internet] [Doctoral dissertation]. University of New South Wales; 2017. [cited 2021 Apr 13]. Available from: http://handle.unsw.edu.au/1959.4/59629 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:49162/SOURCE02?view=true.

Council of Science Editors:

Zhang Y. Nanostructure Analysis of In-flame Soot Particles in a Diesel Engine. [Doctoral Dissertation]. University of New South Wales; 2017. Available from: http://handle.unsw.edu.au/1959.4/59629 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:49162/SOURCE02?view=true

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Open Access Theses and Dissertations