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In present GDI engines, multiple injection strategies are often employed for engine cold start mixture formation. In the future, these strategies may also be used to control the combustion process, and to prevent misfiring or high emission levels. While the processes occurring during individual injections of GDI injectors have been investigated by a number of researchers, this paper concentrates on the interactions of multiple injection events. Even though multiple injection strategies are already applied in most GDI engines, the impact of the first injection event on the second injection event has not been analyzed in detail yet. Different optical measurement techniques are used in order to investigate the interaction of the two closely timed injection events, as well as the effect of dwell time and the in-cylinder conditions. The injector investigated is a GDI piezo injector with an outwardly opening needle.

Effects of fuel cell material properties on water management were numerically investigated using Volume of Fluid (VOF) method in the FLUENT. The results show that the channel surface wettability is an important design variable for both serpentine and interdigitated flow channel configurations. In a serpentine air flow channel, hydrophilic surfaces could benefit the reactant transport to reaction sites by facilitating water transport along channel edges or on channel surfaces; however, the hydrophilic surfaces would also introduce significantly pressure drop as a penalty. For interdigitated air flow channel design, it is observable that liquid water exists only in the outlet channel; it is also observable that water distribution inside GDL is uneven due to the pressure distribution caused by interdigitated structure. An in-situ water measurement method, neutron imaging technique, was used to investigate the water behavior in a PEM fuel cell.

Simulations using CFD and chemical kinetics models have been applied to gain a better understanding of the effect of the recirculated gases on the autoignition process during cold starting of a direct injection diesel engine. The cranking gases recirculated (CGR) contain fuel vapor and partial oxidation products which affect the autoignition process in different ways. Some hydrocarbons (HCs) species enhance the reaction rates and reduce ignition delay. Meanwhile other HCs species and the partial oxidation products of the autoignition process have an opposing effect. The simulation covered a wide range of the hydrocarbons and aldehydes concentrations and their effect on the ignition delay in a 1.2L Ford DIATA 4-cylinders, water cooled, turbocharged and intercooled diesel engine. The simulated opposing effects of HCs and HCHO on the ignition delay are validated by experimental results at room temperature.

A global characterization of the spray distribution of various current and development types of automotive fuel injectors was obtained. Axial and radial measurement of droplet sizes, velocities and volume fluxes were made with a phase Doppler particle analyzer (PDPA) for a transient port injector spray in quiescent atmospheric conditions. Time-resolved measurements involving the time-of-arrival of each droplet associated with its size and velocity components were also acquired. Additionally, the liquid sprays emanating from various types of port fuel injectors were visualized, through planar laser induced fluorescence (PLIF) technique, at different time instants. Such detailed study provides an improved understanding of the temporal or unsteady behavior of port injector spray.

The flow structure inside the catalytic converter of gasoline engines is very important for consideration of the catalyst light-off condition, converter durability and conversion efficiency. However, the available experimental data under actual engine exhaust conditions are quite limited due to its complicated configuration, critical operating conditions and difficult optical access. Therefore, an experimental study was performed, using laser Doppler velocimetry technique, to measure the velocity distributions inside two production dual-monolith catalytic converters fitted on a firing gasoline engine over several engine operating conditions. This paper reports the normal velocity characteristics measured in a plane 1 mm away from the front surface of first monolith. A small fraction of titanium (IV) isopropoxide was dissolved in gasoline for generating titanium dioxide seeding particles during the engine combustion.

As engine efficiency targets continue to rise, additional improvements must consider reduction of heat transfer losses. The development of advanced heat transfer models and realistic boundary conditions for simulation based engine design both require accurate in-cylinder wall temperature measurements. A novel dual wavelength infrared diagnostic has been developed to measure in-cylinder surface temperatures with high temporal resolution. The diagnostic has the capability to measure low amplitude, high frequency temperature variations, such as those occurring during the gas exchange process. The dual wavelength ratio method has the benefit of correcting for background scattering reflections and the emission from the optical window itself. The assumption that background effects are relatively constant during an engine cycle is shown to be valid over a range of intake conditions during motoring.

A hot and cold water mixing process with a steam condenser and a chilled water heat exchanger is set up for an engine EGR fouling test. The test rig has water recycled in the loop of a pump, heat exchangers, a three-way mixing valve, and a test EGR unit. The target unit temperature is controlled by a heating, cooling and mixing process with individual valves regulating the flow-rate of saturated steam, chilled water and mixing ratio. The challenges in control design are the dead-time, interaction, nonlinearity and multivariable characteristics of heat exchangers, plus the flow recycle in the system. A systems method is applied to extract a simple linear model for control design. The method avoids the nonlinearity and interaction among different temperatures at inlet, outlet and flow-rate. The test data proves the effectiveness of systems analysis and modeling methodology. As a result, the first-order linear model facilitates the controller design.