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This work experimentally investigated the effect of fuel temperature on nano-scale particulate matter (PM) from a Direct-Injection Spark-Ignition (DISI) engine. The first part of the investigation focused on the effect of fuel temperature on combustion characteristics and the second part focused on the engine-out particulate matter. This study found that the injection of chilled fuel into the combustion chamber led to higher in-cylinder pressure, longer duration of combustion (DOC), lower PM number and lower Geometric Mean Diameter (GMD) of the PM than the injection of fuel at ambient temperature.

This work attempted to correlate the ultra fine particulate count to the flame propagation time, in-cylinder peak pressure, and in-cylinder ageing time (the time the particulates stay inside the cylinder) of a throttle body gasoline injected engine. The engine was tested at different loads and speeds ranging from 20 Nm to 100 Nm and 2000 to 3400 rpm respectively. A fast particle spectrometer, a mass spectrometer, and an in-cylinder pressure measurement system were used to characterize the particulate emission. This work identified the correlation between the nucleation of particulates and rate of burning, the particulate count for particles size greater than 200 nm and the in-cylinder ageing time. It identified that an increase in engine load at constant speed increased the particle number density of the 10 nm diameter particles; the effect was less significant on the particles of diameter greater than 50 nm and almost absent on particles of diameter greater than 200 nm.

This study attempted to identify the correlation between the gaseous species and nano-scale exhaust particles from a gasoline engine using simultaneous particulate and gaseous measurement. A fast particle spectrometer for particulates and a quadrupole mass spectrometer for gaseous species were employed in this work. Two commercially available super unleaded gasoline fuels were used in this study to establish a link between the gaseous species and nano-scale particulates. The possible correlations between the gaseous species such as acetylene, 1, 5 hexadyne, toluene, benzene and furaldehyde and nano-scale particles were identified and are detailed in this paper.

Recent developments in measurement techniques enabled researchers to measure ultra-fine particulates of nano-scale range and provided more evidence that the smaller particulates typically emitted from gasoline engines may have more severe impacts on human respiratory system than the bigger particulates from diesel engines. The knowledge of the characteristics of particulates from gasoline engines, especially, the effect of fuel borne additives is sparse. This work presents the findings from a study into the effect of aftermarket additives on nano-scale particulates. Four commercially available fuel borne additives used in gasoline engines mainly by private vehicle owners in the United Kingdom were selected for this study. The combustion and emission performance of the additive fuels were compared against that of commercially available gasoline fuel using a 4-stroke, throttle body injected gasoline engine.

The work presented investigates the effect of road gradient, head-wind, horizontal road curvature, changes in tyre rolling radius, vehicle drag co-efficient and vehicle weight on real-world emission levels of a modern EURO-IV vehicle. A validated steady-state engine performance map based vehicle modeling approach has been used for the analysis. The results showed that a generalized correction factor to include the effect of road-gradient on real-world emission levels might not yield accurate results, since the emission levels are strongly dependent on the position of the vehicle operating parameters on the engine maps. In addition, it also demonstrated that the inclusion of horizontal road curvature such as roundabouts and traffic islands are essential for the estimation of the real-world emission levels.

This paper investigates the effect of tailpipe orientation on carbon monoxide (CO) dispersion patterns which is directly linked to the CO exposure levels that a cyclist can experience in Oxford City. The most common tailpipe orientations used in Oxford city vehicles have been identified. Following this, the dispersion patterns from various tailpipe orientations were experimentally investigated and the results used to construct contour maps of CO dispersion patterns. The contour maps were used to estimate the likely exposure levels a cyclist can experience. The real-world cyclist CO exposure levels were also measured in two routes in Oxford city and compared with those obtained from the contour maps and data from fixed site monitoring station. The results show that CO levels in the cycle lane are significantly affected by the tailpipe orientation and are higher than the recommended World Health Organization (WHO) exposure levels.

The present work investigated the real-world emission performance of a typical light-duty gasoline vehicle to identify the most significant vehicle operating parameter responsible for excessive real-world emission levels. Based upon tailpipe-out emission levels two distinct portions in the engine maps could be identified; a clean portion of the map, which covers the engine operating points within the European the legislative drive cycle, and an unclean portion of the map that is outside the legislative testing. A systematic investigation of the tailpipe-out emission levels for the real-world drive cycle showed that the levels of vehicle speed and acceleration are immaterial if the vehicle operating points remain within the cleaner zone of the engine map. The methodical approach followed to identify the most significant vehicle operating parameter responsible for the real-world emission levels is given in this paper.

This paper investigates an approach to modelling real-world drive cycles for the prediction of fuel economy and emission levels. It demonstrates that a steady-state engine performance data based modelling approach can be used for real-world drive cycle simulation. It identifies and demonstrates that a steady-state performance data-based approach is the only current viable approach for real-world tailpipe-out CO level predictions. It also identifies quantitatively the difference between the modal emission measurements and constant volume sampling (CVS) bag values for emission modelling validation. A systematic validation and sensitivity analysis of the modelling approach is also described.

Increasing design emphasis on factors such as styling, fuel reduction and soundproofing raises a number of additional problems concerning under-bonnet aerodynamics and heat exchange. Because experimental work on successive prototypes entails heavy penalties in terms of development lead-time, it is becoming more and more important to integrate simulation from the pilot study stage, as a way to minimize the number of prototypes. Fortunately, early integration of under-bonnet air-flow modelling is becoming an increasingly viable proposition, thanks to the spectacular increase in computer processing power, which stimulates the development of more efficient meshing software and facilitates the generalized implementation of CAD techniques throughout the design processes. Modelling thus emerges as a new investigatory method that enhances the design office's capabilities by enabling it to adopt a sharper design focus right from the pilot project stage.