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Exhaust gas recirculation, fuel injection strategy and boost pressure are among the key enablers to attain low NOx and soot emissions simultaneously on modern diesel engines. In this work, the individual influence of these parameters on the emissions are investigated independently for engine loads up to 8 bar IMEP. A single-shot fuel injection strategy has been deployed to push the diesel cycle into low temperature combustion with EGR. The results indicated that NOx was a stronger respondent to injection pressure levels than to boost when the EGR ratio is relatively low. However, when the EGR level was sufficiently high, the NOx was virtually grounded and the effect of boost or injection pressure becomes irrelevant. Further tests indicated that a higher injection pressure lowered soot emissions across the EGR sweeps while the effect of boost on the soot reduction appeared significant only at higher soot levels.

Fatigue behavior of aluminum alloys under multiaxial loading was investigated with both cast aluminum A356-T6 and wrought alloy 6063-T6. The dominant multiaxial fatigue crack preferentially nucleates from flaws like porosity and oxide films located near the free surface of the material. In the absence of the flaws, the cracking/debonding of the second phase particles dominates the crack initiation and propagation. The number of cracked/debonded particles increases with the number of cycles, but the damage rate depends on loading paths. Among various loading paths studied, the circle loading path shows the shortest fatigue life due to the development of complex dislocation substructures and severe stress concentration near grain/cell boundaries and second phase particles.

Modern diesel engines employ a multitude of strategies for oxides of nitrogen (NOx) emission abatement, with exhaust gas recirculation (EGR) being one of the most effective technique. The need for a precise control on the intake charge dilution (as a result of EGR) is paramount since small fluctuations in the intake charge dilution at high EGR rates may cause larger than acceptable spikes in NOx/soot emissions or deterioration in the combustion efficiency, especially at low to mid-engine loads. The control problem becomes more pronounced during transient engine operation; currently the trend is to momentarily close the EGR valve during tip-in or tip-out events. Therefore, there is a need to understand the transient EGR behaviour and its impact on the intake charge development especially under unstable combustion regimes such as low temperature combustion.

This study investigated neat n-butanol combustion, emissions and thermal efficiency characteristics in a compression ignition (CI) engine by using two fuelling techniques - port fuel injection (PFI) and direct injection (DI). Diesel fuel was used in this research for reference. The engine tests were conducted on a single-cylinder four-stroke DI diesel engine with a compression ratio of 18.2 : 1. An n-Butanol PFI system was installed to study the combustion characteristics of Homogeneous Charge Compression Ignition (HCCI). A common-rail fuel injection system was used to conduct the DI tests with n-butanol and diesel. 90 MPa injection pressure was used for the DI tests. The engine was run at 1500 rpm. The intake boost pressure, engine load, exhaust gas recirculation (EGR) ratio, and DI timing were independently controlled to investigate the engine performance.

Proton exchange membrane fuel cells (PEMFC), which convert the chemical energy into electrical energy directly through electrochemical reactions, are widely considered as one of the best power sources for new energy vehicles (NEV). Some of the major advantages of a PEMFC include high power density, high energy conversion efficiency, minimum pollution, low noise, fast startup and low operating temperature. The Membrane Electrode Assembly (MEA) is one of the core components of fuel cells, which composes catalyst layers (CL) coated proton exchange membrane (PEM) and gas diffusion layers (GDL). The performance of MEA is closely related to mass transportation and the rate of electrochemical reaction. The MEA plays a key role not only in the performance of the PEMFCs, but also for the reducing the cost of the fuel cells, as well as accelerating the commercial applications. Commercialized large-size MEA directly plays a major role in determining fuel cell stack and vehicle performance.

This study describes a zero-dimensional algorithm for tracking the intake dilution in real-time. The inputs to the model are the oxygen concentration from the exhaust oxygen sensor, the manifold air pressure and temperature (MAP/MAT), the mass air flow (MAF) and the estimated fuel injected per cycle from the engine control module. The intake manifold, the exhaust manifold and EGR system are discretized into 3 volumes and the detailed concentrations of the gas species comprising the exhaust, EGR and intake streams are tracked at each time step (on a cycle-by-cycle basis). The model does not need the EGR ratio to be known in advance and is also applicable to oxygenated fuels such as ethanol. The model response is tuned to a multi-cylinder engine and the model output is empirically validated against a wide range of engine operations including load and EGR transients.

Crashworthiness is one of the most important performances of vehicles, and the front rails are the main crash energy absorption parts during the frontal crashing process. In this paper, the front rail was simplified to a thin-walled beam with a cross section of single-hat which was made of steel and aluminum. And the two boards of it were connected by riveting without rivets. In order to optimize its crashworthiness, the thickness (t), radius (R) and the rivet spacing (d) were selected as three design variables, and its specific energy absorption was the objective while the average impact force was the constraint. Considering the error of manufacturing and measurements, the parameters σs and Et of the steel were selected as the uncertainty variables to improve the design reliability. The algorithm IP-GA and the approximate model-RBF (Radial Basis Function) were applied in this nonlinear uncertainty optimization.

The work-hardening response of TRIP780 steel subjected to strain-path changes was investigated using two-stage tension experiments. Large specimens were prestrained and then sub-sized samples were subjected to tension along various directions. The influence of strain-path changes on flow stress and work hardening performance was discussed in detail. The specific plastic work was calculated to compare the kinematic hardening behaviour after strain-path changes. The results showed that transient hardening was observed for TRIP780 sheets subjected to orthogonal strain-path change. The strain-hardening exponent (n-value) was influenced by prestraining levels and the strain path. The n-value exhibited a greater decrease under an orthogonal strain-path change. Prestraining can delay the onset of high work hardenability of TRIP steels. It is meaningful for the safety design of vehicles.

The present work proposed to implement oxy-fuel combustion mode into a homogeneous charge compression ignition engine to reduce complexity in engine emissions after-treatment and lower carbon dioxide emission. The combination of oxy-fuel combustion mode with homogeneous charge compression ignition engine can be further optimized by the utilization of direct high temperature and pressure water injection to improve cycle performance. A retrofitted conventional diesel engine coupled with port fuel injection and direct water injection is utilized in this study. A self-designed oxygen and carbon dioxide mixture intake system with flexible oxygen fraction adjustment ability is implemented in the test bench to simulate the adoption of exhaust gas recirculation. Water injection system is directly installed in the combustion chamber with a modified high speed solenoid diesel injector.

In this study, impacts of neat n-butanol fuel injection parameters on direct injection (DI) compression ignition (CI) engine performance were investigated to gain knowledge for understanding the fuel injection strategies for n-butanol. The engine tests were conducted on a four-stroke single-cylinder DI CI engine with a compression ratio of 18.2:1. The effects of fuel injection pressure (40, 60 and 90 MPa) and injection timing in a single injection strategy were investigated. The results showed that an increase in injection pressure significantly reduced nitrogen oxides (NOx) emissions which is the opposite trend seen in conventional diesel combustion. The parallel use of a higher injection pressure and retarded injection timing was a proposed method to reduce NOx and cylinder pressure rise rate simultaneously. NOx was further reduced by using exhaust gas recirculation (EGR) while keeping near zero soot emissions.

In this work, empirical investigations of the diesel-ethanol Premixed Pilot-Assisted Combustion (PPAC) are carried out on a high compression ratio (18.2:1) single-cylinder diesel engine. The tests focus on determining the minimum ethanol fraction for ultra-low NOx & soot emissions, effect of single-pilot vs. twin-pilot strategies on emissions and ignition controllability, reducing the EGR requirements, enabling clean combustion across the load range and achieving high efficiency full-load operation. The results show that both low NOx and almost zero soot emissions can be achieved but at the expense of higher unburned hydrocarbons. Compared to a single-pilot injection, a twin-pilot strategy reduces the soot emissions significantly and also lowers the NOx emissions, thereby reducing the requirements for EGR. The near-TDC pilot provides excellent control over the combustion phasing, further reducing the need of a higher EGR quantity for phasing control.

In recent years, particulate matters (PM) emissions from gasoline direct injection (GDI) engines have been gradually paid attention to, and the hydrous ethanol has a high oxygen content and a fast burning rate, which can effectively improve the combustion environment. In addition, Exhaust gas recirculation (EGR) can effectively reduce engine NOx emissions, and combining EGR technology with GDI engines is becoming a new research direction. In this study, the effects of hydrous ethanol gasoline blends on the combustion and emission characteristics of GDI engines are analyzed through bench test. The results show that the increase of the proportion of hydrous ethanol can accelerate the burning rate, shorten the combustion duration by 7°crank angle (CA), advance the peak moment of in-cylinder pressure and rate of heat release (RoHR) and improve the combustion efficiency. The hydrous ethanol gasoline blends can effectively improve the gaseous and PM emissions of the GDI engine.

To meet the request of China National 6b emission regulations which will be officially implemented in China, firstly including the RDE emission test limits, the transient emissions on real road condition are paid more attention. A non-plug-in hybrid light-duty gasoline vehicles (HEV) sold in the Chinese market was selected to study real road emissions employed fast response NOx analyzer from Cambustion Ltd. with a sampling frequency of 100Hz, which can measure the missing NO peaks by standard RDE gas analyzer now. Emissions from PEMS were also recorded and compared with the results from fast response NOx analyzer. The concentration of NOx emissions before and after the Three Way Catalyst (TWC) of the hybrid vehicle were also sampled and analyzed, and the working efficiency of the TWC in real road driving process was investigated.

We are witnessing a rapid and ongoing expansion of nanoscience, driven by potential applications in advanced materials and nanotechnology. There is a race to develop techniques that may allow controlling the size, shape of nanostructures that can allow the tuning of their optical and electronic properties. Plasmonics is a field that encompasses and profits from the optical enhancement in nanostructures that support plasmon excitations. One of these new techniques is surface-enhanced Raman scattering (SERS), commonly used for nanostructure characterization. In the present report, we present a theoretical model for plasmon excitation and electric field enhancement that help to provide an explanation for the special features observed in experimental SERS. Two sets of experimental results are discussed illustrating the make out of the signature of the plasmonics producing the optical enhancement.

Experimental and numerical studies have been completed on the deformation behaviour of round AA6061-T6 aluminum extrusions during an axial cutting deformation mode employing both curved and straight deflectors to control the bending deformation of petalled side walls. Round extrusions of length 200 mm with a nominal wall thickness of 3.175 mm and an external diameter of 50.8 mm were considered. A heat treated 4140 steel alloy cutter and deflectors, both straight and curved, were designed and manufactured for the testing considered. The four blades of the cutter had an approximate average thickness of 1.00 mm which were designed to penetrate through the round AA6061-T6 extrusions. Experimental observations illustrated high crush force efficiencies of 0.82 for the extrusions which experienced the cutting deformation mode with the deflectors. Total energy absorption during the cutting process was approximately 5.48 kJ.

Empirical results indicated that the engine emission and fuel efficiency of low-temperature combustion (LTC) cycles can be optimized by adjusting the fuel-injection scheduling in order to obtain appropriate combustion energy release or heat-release rate patterns. Based on these empirical results the heat-release characteristics were correlated with the regulated emissions such as soot, hydrocarbon and oxides of nitrogen. The transition from conventional combustion to LTC with the desired set of heat-release rate has been implemented. This transition was facilitated with the simplified heat-release characterization wherein each of the consecutive engine cycles was analyzed with a real-time controller embedded with an FPGA (field programmable gate array) device. The analyzed results served as the primary feedback control signals to adjust fuel injection scheduling. The experimental efforts included the boost/backpressure, exhaust gas recirculation, and load transients in the LTC region.

Fatigue analysis incorporating explicit finite element simulation was conducted on a forged magnesium wheel model where a rotating bend moment was applied to the hub to simulate rotary fatigue testing. Based on wheel fatigue design criteria and a developed fatigue post-processor, the safety factor of fatigue failure was calculated for each finite element. Fatigue failure was verified through experimental testing. Design modifications were proposed by increasing the spoke thickness. Further numerical and experimental testing indicated that the modified design passed the rotary fatigue test.

Simultaneous low NOx (< 0.15 g/kWh) & soot (< 0.01 g/kWh) are attainable for enhanced premixed combustion that may lead to higher levels of hydrocarbons and carbon monoxide emissions as the engine cycles move to low temperature combustion, which is a departure from the ultra low hydrocarbon and carbon monoxide emissions, typical of the high compression ratio diesel engines. As a result, the fuel efficiency of such modes of combustion is also compromised (up to 5%). In this paper, advanced strategies for fuel injection are devised on a modern 4-cylinder common rail diesel engine modified for single cylinder research. Thermal efficiency comparisons are made between the low temperature combustion and the conventional diesel cycles. The fuel injection strategies include single injection with heavy EGR, and early multi-pulse fuel injection under low or medium engine loads respectively.

Extensive empirical work indicates that the exhaust emission and fuel efficiency of modern common-rail diesel engines characterise strong resilience to biodiesel fuels when the engines are operating in conventional high temperature combustion cycles. However, as the engine cycles approach the low temperature combustion (LTC) mode, which could be implemented by the heavy use of exhaust gas recirculation (EGR) or the homogeneous charge compression ignition (HCCI) type of combustion, the engine performance start to differ between the use of conventional and biodiesel fuels. Therefore, a set of fuel injection strategies were compared empirically under independently controlled EGR, intake boost, and exhaust backpressure in order to improve the neat biodiesel engine cycles.

Low temperature combustion (LTC), though effective to reduce soot and oxides of nitrogen (NOx) simultaneously from diesel engines, operates in narrowly close to unstable regions. Adaptive control strategies are developed to expand the stable operations and to improve the fuel efficiency that was commonly compromised by LTC. Engine cycle simulations were performed to better design the combustion control models. The research platform consists of an advanced common-rail diesel engine modified for the intensified single cylinder research and a set of embedded real-time (RT) controllers, field programmable gate array (FPGA) devices, and a synchronized personal computer (PC) control and measurement system.