Design and development of auxiliary components for a new two-stroke, stratified-charge, lean-burn gasoline engine

A unique stepped-piston engine was developed by a group of research engineers at Universiti Teknologi Malaysia (UTM), from 2003 to 2005. The development work undertaken by them engulfs design, prototyping and evaluation over a predetermined period of time which was iterative and challenging in nature. The main objective of the program is to demonstrate local R&D capabilities on small engine work that is able to produce mobile powerhouse of comparable output, having low-fuel consumption and acceptable emission than its crankcase counterpart of similar displacement. A two-stroke engine work was selected as it posses a number of technological challenges, increase in its thermal efficiency, which upon successful undertakings will be useful in assisting the group in future powertrain undertakings in UTM. In its carbureted version, the single-cylinder aircooled engine incorporates a three-port transfer system and a dedicated crankcase breather. These features will enable the prototype to have high induction efficiency and to behave very much a two-stroke engine but equipped with a four-stroke crankcase lubrication system. After a series of analytical work the engine was subjected to a series of laboratory trials. It was also tested on a small watercraft platform with promising indication of its flexibility of use as a prime mover in mobile platform. In an effort to further enhance its technology features, the researchers have also embarked on the development of an add-on auxiliary system. The system comprises of an engine control unit (ECU), a directinjector unit, a dedicated lubricant dispenser unit and an embedded common rail fuel unit. This support system was incorporated onto the engine to demonstrate the finer points of environmental-friendly and fuel economy features. The outcome of this complete package is described in the report, covering the methodology and the final characteristics of the mobile power plant

An Empirical and Simulation Study on Pressure Wave Propagation in Diesel Manifolds

Pressure wave oscillations occurring in both the intake and exhaust manifolds can potentially be applied to exhaust gas recirculation (EGR) and selective catalytic reduction (SCR), to increase their distribution efficiency and further reduce nitric oxide (NOx) emissions. The work consists of an in depth study on pressure wave propagation in diesel exhaust manifolds for various operating conditions, such as: RPM, IMEP, EGR, Post-injection, backpressure, runner length, runner diameter, and position sweeps. The effect of pressure wave propagation in diesel manifolds, by varying such engine operating parameters, and geometric exhaust configurations, have been demonstrated empirically, and by simulation. By understanding the characteristic behavior of the pressure waves, such as frequency, amplitude, and phasing, under different engine operating conditions, better EGR and SCR distribution strategies may be found. This may be done by implementing different manifold configurations and injection strategies, to the EGR and SCR systems, respectively

Impact of potential engine malfunctions on fuel consumption and gaseous emissions of a Euro VI diesel truck

© 2019 Elsevier Ltd Although new vehicles are designed to comply with specific emission regulations, their in-service performance would not necessarily achieve them due to wear-and-tear and improper maintenance, as well as tampering or failure of engine control and exhaust after-treatment systems. In addition, there is a lack of knowledge on how significantly these potential malfunctions affect vehicle performance. This study was therefore conducted to simulate the effect of various engine malfunctions on the fuel consumption and gaseous emissions of a 16-tonne Euro VI diesel truck using transient chassis dynamometer testing. The simulated malfunctions included those that would commonly occur in the intake, fuel injection, exhaust after-treatment and other systems. The results showed that all malfunctions increased fuel consumption except for the malfunction of EGR fully closed which reduced fuel consumption by 31%. The biggest increases in fuel consumption were caused by malfunctions in the intake system (16%–43%), followed by the exhaust after-treatment (6%–30%), fuel injection (4%–24%) and other systems (6%–11%). Regarding pollutant emissions, the effect of engine malfunctions on HC and CO emissions was insignificant, which remained unchanged or even reduced for most cases. An exception was EGR fully open which increased HC and CO emissions by 343% and 1124%, respectively. Contrary to HC and CO emissions, NO emissions were significantly increased by malfunctions. The largest increases in NO emissions were caused by malfunctions in the after-treatment system, ranging from 38% (SCR) to 1606% (DPF pressure sensor). Malfunctions in the fuel injection system (24%–1259%) and intercooler (438%–604%) could also increase NO emissions markedly. This study demonstrated clearly the importance of having properly functioning engine control and exhaust after-treatment systems to achieve the required performance of fuel consumption and pollutant emissions

Stratified charge rotary aircraft engine technology enablement program

The multifuel stratified charge rotary engine is discussed. A single rotor, 0.7L/40 cu in displacement, research rig engine was tested. The research rig engine was designed for operation at high speeds and pressures, combustion chamber peak pressure providing margin for speed and load excursions above the design requirement for a high is advanced aircraft engine. It is indicated that the single rotor research rig engine is capable of meeting the established design requirements of 120 kW, 8,000 RPM, 1,379 KPA BMEP. The research rig engine, when fully developed, will be a valuable tool for investigating, advanced and highly advanced technology components, and provide an understanding of the stratified charge rotary engine combustion process

Design and investigation of a diesel engine operated on pilot ignited LPG

This thesis explores the idea of igniting LPG in a compression ignition diesel engine using pilot diesel injection as spark ignition medium. The main advancement in using this technology on current diesel engines is the establishment of a better balance between NOx and PM emissions without losing too much of the CO2 benefits of diesel. With the advent of common rail diesel engines, it is now possible to get control of pilot diesel injection and make the LPG and diesel control systems work together. Combined diesel and LPG operation is a new subject for engine research, so the thesis moves on to consider the results from detailed engine simulation studies that explore the potential benefits of the mix. Subsequent simulations of a modern four cylinder dCi engine suggest that with closer control over the pilot diesel injection, diesel like performance can be obtained, hopefully with less emissions than currently expected from diesel only operation. A single cylinder variable compression ratio research engine was developed to explore diesel /LPG dual fuel operation. A second generation common rail injection rig was also developed for the engine and for fuel spray characterisation. Engine experiments proved the concept of using a modest charge of pilot injected diesel for igniting a larger dose of port injected LPG. The experimental work results suggest that combining diesel common rail injection technology with the state of the art LPG injection systems, it is possible to establish a better balance between NOx/ PM emissions without losing too much of the CO2 benefits from the diesel operation

Development of a Rate of Injection Bench and Constant Volume Combustion Chamber for Diesel Spray Diagnostics

To help understand the complex fuel spray combustion phenomena in modern diesel engine using high injection pressure, a fuel injection test bench and a constant volume combustion chamber were developed and demonstrated in this study for diesel spray diagnostics. Both facilities are significant when linking between spray injection and combustion dynamics and engine performance. This link is important to determine changes needed in order to optimize the performance of a diesel engine. Combustion and emissions of a diesel engine are influenced by the rate of fuel injection which, in turn, is determined by the injection pressure, nozzle geometry, and fuel type. The rate of injection bench capable of studying a modern common-rail injection system was designed, fabricated, and demonstrated in this study. Experimental apparatus included a high pressure fuel pump, a fuel rail, a transient pressure transducer, and a data acquisition and control system. The rates of injection of different injectors with various nozzle diameters and spray angles injecting different types of fuel under different injection schemes were investigated. Results of this study showed that for the same injector, the differences in the rates of injection were negligible under the same injection conditions with variations only in the back pressure from 2.07 MPa to 6.21 MPa. When injection pressure was increased from 75 MPa, to 100 MPa, and to 150 MPa more fuel was injected and the rise and decay of the injection rate also increased. This indicated that fuel exited the nozzle at a faster rate. Subsequently, as injection pressure was increased, a higher peak injection rate was seen. If the same fuel quantity was desired, injection duration was shortened. When comparing the rate of injection for diesel and biodiesel blend (i.e, B20 and B100), the rates of injection were comparable but the injected mass of biodiesel was slightly higher because biodiesel has a slightly higher density. On the other hand, the difference in the delay between the electronic injection signal and the onset of injection was negligible for diesel and biodiesel blends using the current common-rail system. Additionally, the rate of injection for the double injection scheme was also studied and results showed that the shape of individual injection in the multiple injection schemes was similar to that of single injection. To further understand the engine in-cylinder combustion process, a constant volume combustion chamber was also developed and demonstrated in this study. With optical access provided by quartz windows, experiments using modern laser imaging and spectroscopy were performed to further understand high-speed diesel fuel jet development. The previous experiment was revisited using a superior camera to capture higher quality images to study the diesel spray structure. The previous constant volume heated chamber was then converted to a constant volume pre-combustion chamber. During this conversion, seals were redesigned and new O-rings seals were utilized. In addition, a high speed mixing fan, powerful ignition system, and data acquisition and control system were implemented. After the conversion, it was demonstrated that the new combustion chamber could attain temperature up to 919 K while showing negligible leaks. Even higher temperature and pressure could be attained if more combustible gas mixture was inputted. The combustion chamber developed in this study can be readily utilized to study high-speed diesel jet combustion under high-pressure and high-temperature environments

Development of Laser Welded Common Rail with Radial Connected Pressure Sensor (RPS)

Tato diplomová práce se zabývá vývojem laserem svařeného common railu s radiálně připojeným snímačem tlaku RPS. Tento nový koncept požadovaný od firmy Bosch Diesel s.r.o. Jihlava by měl být jednodušeji modifikovatelný, a měl by být snadněji zabudovatelný do motorového prostoru. V této diplomové práci jsem navrhl několik konceptů, které jsem dále analyzoval, ověřoval v příslušných softwarech, vyvíjel, a nakonec jsem zúžil výběr na jedno nejvhodnější řešení, které jsem doporučil a obhájil v závěru.This dissertation deals with a development of a laser welded common rail with a radially attached RPS sensor of pressure. The new concept required by Bosch Diesel s.r.o. Jihlava should be more modifiable and it should be easily integrated with the engine compartment. In this dissertation I suggested a number of concepts that I further analysed, verified in appropriate software, developed, and finally narrowed the selection down to the most suitable solution, which is recommended and justified in the conclusion.

Reduced Exhaust Emissions Through Blending n-Butanol with Ultra Low Sulfur Diesel and Synthetic Paraffinic Kerosene in Reactivity Controlled Compression Ignition Combustion

Increasing restrictions on the emitted exhaust emissions in diesel engines are becoming a more challenging task than in previous years. An electronic common rail fuel injection system and a port fuel injection (PFI) system were developed for an experimental engine to research dual fuel combustion. The experimental research was conducted at 1500 rpm and 4, 5, and 6 bar indicated mean effective pressure (IMEP). n-Butanol was port fuel injected at a 60% by mass fraction coupled with direct injection (DI) of three fuels, including ultra-low sulfur diesel (ULSD RCCI), a 50-50 wt-% blend of ULSD and butanol (ULSD-Bu RCCI), and a 50-50 wt-% blend of Fischer Tropsch synthetic paraffinic kerosene and butanol (S8-Bu RCCI). Split DI events of high reactivity fuels were used to maintain constant combustion phasing. The fuel blends increased pressure rise rates and ringing intensity drastically compared to conventional diesel combustion (CDC) and ULSD RCCI. Both butanol fuel bends had lower ignition quality than ULSD, increasing the mass fraction at the first DI event, increasing heat release rates up to 30%. ULSD-Bu RCCI had the shortest ignition delay and combustion duration due to the low cetane number. NOx and soot were simultaneously reduced up to 90% with RCCI compared to CDC. Unburned hydrocarbons were increased for RCCI fuel blends. S8-Bu RCCI resulted in reductions in hydrocarbon emissions compared to ULSD-Bu RCCI. Results display large emission reductions of harmful pollutants, such as NOx and soot, with RCCI combustion and the potential of alternative fuels in diesel combustion

Optimal Conditions for Measuring Ignition Quality in Non-Engine Tests

Experiments and simulation work were conducted to explore the conditions that influence ignition events in a constant volume environment. Experiments were conducted in a Fuel Ignition Tester, produced by CFR Engines, Inc., and in a prototype combustion chamber to observe the combustion of diesel fuels and primary reference fuels. These experiments attempted to isolate experimental conditions that would provide repeatable pressure measurements. These experiments showed that the fuel spray properties and the environmental conditions, such as initial temperature and initial pressure, are significantly influential in these results. Simulation work was conducted in Converge 2.2.0 to explore these conditions further. The simulations were focused on the examination of the effects of the injected fuel mass, the geometry of the chamber, and temperature inhomogeneities on the ignition delay results for n-dodecane, a well-defined diesel surrogate fuel. These simulations revealed that combustion events are sensitive to the initial temperature of the environment and slightly sensitive to fuel mass. It was found that geometry effects have significant effects on fuel-air mixing, which in turn has large effects on the intermediate reactions in low-temperature combustion of hydrocarbons. Ultimately, it was concluded that conditions should be sought to reduce the system’s sensitivity to slight changes in fuel mass in order to produce a reliable direct correlation between ignition delay and cetane number. This study acts to further the development of an optimal CVCC experimental setup to measure ignition quality of diesel fuels. Based on the results from this thesis, a reliable direct correlation between ignition delay and cetane number could be developed through iterations on the conditions in CVCC experiments, through further simulation and experimental work. Simulation work from this study could be extended to explore incremental changes in fuel mass at different fuel mass conditions. This would provide insight into which fuel mass conditions are least sensitive to slight changes on an experiment-by-experiment basis. These simulation results could then be applied to further experiments to determine the repeatability of the pressure results at those fuel mass conditions

Investigating Sustainable Fuel Effects on Mixing and Combustion through Design and Development of a Gasoline Direct Injection Optically Accessible Engine

Due to ever-growing sustainability issues, more demanding exhaust emission regulations are imposed on internal combustion engines. There is growing introduction of full electrification but, as there are practical issues regarding the full electrification, internal combustion engines are proven to be still useful and often coupled with electric motors. It is, therefore, vital to establish detailed understandings of in-cylinder combustion processes so that the release of greenhouse gas and production of pollutant emissions can be reduced and minimised. Therefore, novel fuels, such as second-generation biofuels, are thoroughly studied to explore possible use as future fuels for hybrid gasoline direct injection powertrains which are derived from sustainable feedstock and provide efficient energy release. For this project, a novel optical engine was designed that facilitate easy access to the piston and rapid cleaning of the piston crown window. A state-of-the-art gasoline direct injection engine was selected for hybrid applications. The initial design of the optical engine was modified to resolve the slackness in the extended timing chains. As the optical engine adopted the Bowditch system and only number 1 cylinder operated, various auxiliary components were also designed and developed to accommodate optical systems and oil circulation, and consider the change in the crankshaft balancing and volume of the air intake. Furthermore, an external fuel supply system was designed to enable a use of different fuels, while minimising a risk of damaging or contaminating the conventional fuel supply lines, by allowing easy cleaning processes. To quantitatively compare the difference in both spray and combustion images between various fuels, MATLAB codes were developed to process the captured images from a high-speed camera. Seven fuels were tested namely gasoline, ethanol, acetic acid, anisole, guaiacol, 2-MF and 2-MTHF; one a reference fossil fuel, one a first-generation biofuel and five second-generation biofuels, respectively. Three different injection timings were applied to simulate stratified, quasi-homogeneous and homogeneous states at low and high injection pressures for combustion studies, with only the injection pressure varied for the constant injection timing at the stratified spray studies. In general, injection pressure did not have a significant effect on soot formation, with exception for anisole, with injection timing found to be the dominant factor. Ethanol showed a similar spray development pattern to that of gasoline but displayed narrower sprays around the injector tip and became wider towards the spark plug. Acetic acid showed an indistinctive spray pattern and all six sprays merged together to form a cloud of fuel. Anisole showed wider sprays than gasoline and ethanol, but exhibited a similar penetration rate. Guaiacol exhibited similar spray characteristics to that of acetic acid, in that it formed a fuel cloud rather than maintaining distinct fuel sprays. Both 2-MF and 2-MTHF showed wide sprays