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Experimental research were carried out on a compression ignition engine with compression ratio of 17.5 with direct-run Naphtha. Exhaust recirculation ratio sweeps were carried out with three injection strategies. Premixed charge compression ignition, partially premixed combustion and low temperature combustion modes were realized and compared with each other. The first injection strategy is single injection. The injection timing is scanned to form partially premixed combustion and low temperature combustion. The second injection strategy features a large early first injection with fixed timing to form premixed charge and a small second injection near top dead center, which was scanned. The third injection strategy is similar to the traditional diesel injection strategy, which has a small pilot injection with fixed interval before the main injection. Results show that all injection strategies could realize both low NOx and low particulate matter emissions simultaneously.

Combustion behaviour and emissions characteristics of different blending ratios of diesel and gasoline fuels (Dieseline) were investigated in a light-duty 4-cylinder compression-ignition (CI) engine operating on partially premixed compression ignition (PPCI) mode. Experiments show that increasing volatility and reducing cetane number of fuels can help promote PPCI and consequently reduce particulate matter (PM) emissions while oxides of nitrogen (NOx) emissions reduction depends on the engine load. Three different blends, 0% (G0), 20% (G20) and 50% (G50) of gasoline mixed with diesel by volume, were studied and results were compared to the diesel-baseline with the same combustion phasing for all experiments. Engine speed was fixed at 1800rpm, while the engine load was varied from 1.38 to 7.85 bar BMEP with the exhaust gas recirculation (EGR) application.

Cold start is a critical operating condition for diesel engines because of the pollutant emissions produced by the unstable combustion and non-performance of after-treatment at lower temperatures. In this research investigation, a light-duty turbocharged diesel engine equipped with a common rail injection system was tested on a transient engine testing bed to study the starting process in terms of engine performance and emissions. The engine (including engine coolant, engine oil and fuel) was soaked in a cold cell at −7°C for at least 8 hours before starting the test. The engine operating parameters such as engine speed, air/fuel ratio, and EGR rate were recorded during the tests. Pollutant emissions (Hydrocarbon (HC), NOx, and particles both in mode of nucleation and accumulation) were measured before and after the Diesel Oxidation Catalyst (DOC). The results show that conversion efficiency of NOx was higher during acceleration period at −7°C start than the case of 20°C start.

Research studies show that 2-methylfuran (MF) is a promising gasoline alternative regarding its positive effect on engine performance and emissions. Before using pure MF in spark ignition engines, it is more likely to be used in a low-level blended form in gasoline. An experimental research study was carried out to investigate the impacts of low-level MF content in gasoline (volumetric 10% MF in blend) on direct-injection spark-ignition (DISI) engine combustion behavior and emissions. The tests were conducted on a single-cylinder spray-guided DISI research engine at an engine speed of 1500 rpm under stoichiometric conditions. The engine loads of 3.5 ~ 8.5 bar IMEP were tested and gasoline-optimized spark timing was used. Furthermore, the effects of spark timing, exhaust gas recirculation (EGR) and valve overlap on NOx emissions were tested.

Exhaust Gas Fuel Reforming has potential to be used for on-board generation of hydrogen rich gas, reformate, and to act as an energy recovery system allowing the capture of waste exhaust heat. High exhaust gas temperature drives endothermic reforming reactions that convert hydrocarbon fuel into gaseous fuel when combined with exhaust gas over a catalyst - the result is an increase in overall fuel energy that is proportional to waste energy capture. The paper demonstrates how the combustion of reformate in a direct injection gasoline (GDI) engine via Reformed Exhaust Gas Recirculation (REGR) can be beneficial to engine performance and emissions. Bottled reformate was inducted into a single cylinder GDI engine at a range of engine loads to compare REGR to conventional EGR. The reformate composition was selected to approximate reformate produced by exhaust gas fuel reforming at typical gasoline engine exhaust temperatures.

In the automotive industry, engine downsizing has been widely accepted as an enabler to improving the fuel economy and reducing the CO₂ emissions. The Atkinson cycle is one of the key technologies. In this paper, the Atkinson cycle with different expansion ratios are compared and analyzed. The investigation is compared with the benchmark whose expansion and compression ratio are identical. The aim is to understand the inherent characteristics of the over-expansion and its effect on the engine performance and emissions. The simulation results show that, the Atkinson cycle produces higher efficiency due to over-expansion. The Atkinson cycle has higher internal EGR compared with the benchmark at equivalent conditions, which contributes to lower the NOx and CO emissions.

In earlier work we have shown that engine operation with oxygenated fuels (e.g., biodiesel) reduces the particulate matter (PM) emissions and extends the engine tolerance to exhaust gas recirculation (EGR) before it reaches smoke limited conditions. The same result has also been reported when high cetane number fuels such as gas-to-liquid (GTL) are used. A likely mechanism for engine-out particulate growth is the reintroduction of particle nuclei into the cylinder through EGR. These recirculated PM particles serve as sites for further condensation and accumulation promoting larger and greater number of particles. In order to further our understanding of EGR influence on total PM production, a diesel particulate filter (DPF) was integrated into the EGR loop. A PM reduction of approximately 50% (soot) was achieved with diesel fuel through filtered EGR, whilst still maintaining a significant NOX reduction.

The paper presents analysis of performance and emission characteristics of a common rail diesel engine operating with RME, with and without EGR. In both cases, the RME fuel was pre-heated in a heat exchanger to control its temperature before being pumped to the common rail. The studied parameters include the in-cylinder pressure history, rate of heat release, mass fraction burned, and exhaust emissions. The results show that when the fuel temperature increases and the engine is operated without EGR, the brake specific fuel consumption (bsfc) decreases, engine efficiency increases and NOx emission slightly decreases. However, when EGR is used while fuel temperature is increased, the bsfc and engine efficiency is independent of fuel temperature while NOx slightly increases.

A prototype catalyst has been developed and integrated within the aftertreatment exhaust system to control the HC, CO, PM and NOx emissions from diesel exhaust gas. The catalyst activity in removing HC and nano-particles was examined with exhaust gas from a diesel engine operating on biodiesel - Rapeseed Methyl Ester (RME). The tests were carried out at steady-state conditions for short periods of time, thus catalyst tolerance to sulphur was not examined. The prototype catalyst reduced the amount of hydrocarbons (HC) and the total PM. The quantity of particulate with electrical mobility diameter in nucleation mode size < 10nm, was significantly reduced over the catalyst. Moreover, it was observed that the use of EGR (20% vol.) for the biodiesel fuelled engine significantly increases the particle concentration in the accumulation mode with simultaneous reduction in the particle concentration in the nuclei mode.

Homogeneous Charge Compression Ignition (HCCI) has emerged as a promising technology for reduction of exhaust emissions and improvement of fuel economy of internal combustion engines. There are generally two proposed methods of realizing the HCCI operation. The first is through the control of gas temperature in the cylinder and the second is through the control of chemical reactivity of the fuel and air mixture. EGR trapping, i.e., recycling a large quantity of hot burned gases by using special valve-train events (e.g. negative valve overlap), seems to be practical for many engine configurations and can be combined with any of the other HCCI enabling technologies. While this method has been widely researched, it is understood that the operating window of the HCCI engine with negative valve overlap is constrained, and the upper and lower load boundaries are greatly affected by the in-cylinder temperature.

The aims of this study are to investigate the responses of a Hybrid III dummy and a human body model in rollover crashes of an SUV, and to assess the effect of seat belts on occupant kinematics in rollover events. A SAEJ2114 rollover test of a 1994 Ford Explorer for two front row dummies with an inflatable tubular structure (ITS) is reconstructed and validated in MADYMO. By removing the ITS, the simulations of the Hybrid III dummy occupants with and without seat belts are obtained. By replacing the dummy models with human body models, with and without seat belts, two other combinations are also modelled. The kinematics and injury risks of two kinds of occupant models are compared and evaluated. Significant differences exist in the motions, and injury levels of the dummies and human body models with and without seat belts. Seat belts can significantly mitigate against occupant ejection.

Natural gas has a high auto-ignition temperature, requiring high compression ratios and/or intake charge heating to achieve HCCI (homogeneous charge compression ignition) engine operation. Previous work by the authors has shown that hydrogen addition improves combustion stability in various difficult combustion conditions. It is shown here that hydrogen, together with residual gas trapping, helps also in lowering the intake temperature required for HCCI. It has been argued in literature that the addition of hydrogen advances the start of combustion in the cylinder. This would translate into the lowering of the minimum intake temperature required for auto-ignition to occur during the compression stroke. The experimental results of this work show that, with hydrogen replacing part of the fuel, a decrease in intake air temperature requirement is observed for a range of engine loads, with larger reductions in temperature noted at lower loads.