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Air pollution from internal combustion engines poses a significant apprehension for both global warming and public health on a worldwide scale. The adoption of hybridization and electrification within the vehicular fleet can help to tackle these challenges. This study evaluates a waste heat recovery system for electric power generation, based on the Inverted Brayton Cycle (IBC) coupled with a high-performance gasoline engine. The Mercedes-Benz CLS 350 CGI engine platform was modelled in AVL Boost software and validated against the reference published experimental data. The engine model was then modified to incorporate the IBC to study the performance of the proposed hybrid propulsion system. The IBC power output was calculated at a wide range of engine speed and load, and results showed that up to 18 kW of extra power output can be generated by the IBC system.

A novel surrogate model is presented, which predicts the engine-out Particle Number (PN) emissions of a light-duty, spray-guided, turbo-charged, GDI engine. The model is developed through extensive CFD analysis, carried out using the Siemens Simcenter STAR-CD, and considers a range of part-load operating conditions and single-variable sweeps where control parameters such as start of injection and injection pressure are varied in isolation. The work is attached to the Ford-led APC6 DYNAMO project, which aims to improve efficiency and reduce harmful emissions from the next generation of gasoline engines. The CFD work focused on the air exchange, fuel spray and mixture preparation stages of the engine cycle. A combined Rosin-Rammler and Reitz-Diwakar model, calibrated over a wide range of injection pressure, is used to model fuel atomization and secondary droplets break-up.

The focus of this study is to analyse changes in soot particle size along the predicted pathlines as they pass through different in-cylinder combustion histories obtained from Kiva-3v CFD simulation with a series of Matlab routines. 3500 locations representing soot particles were selected inside the cylinder at 8° CA ATDC as soot was formed in high concentration at this CA. The dominant soot particle size was recorded within the size range of 20-50 nm at earlier CA and shifted to 10-20 nm after 20° CA ATDC. Soot particle quantities reduce sharply until 20° CA ATDC after which they remain steady at around 1500 particles. Soot particles inside the bowl region tend to stick to the bowl walls and those remaining in the bowl experience an increase in size. Soot particles that move to the upper bowl and squish regions were observed to experience a decrease in size.

Gasoline Direct Injection engines are efficient devices which are rivaling diesel engines with thermal efficiency approaching the 40% threshold at part load. Nevertheless, the GDI engine is an important source of dangerous ultra-fine particulate matter. The long-term sustainability of this technology strongly depends on further improvement of engine design and combustion process. This work presents the initial development of a full-cycle CFD model of a modern wall-guided GDI engine operated in homogeneous and stoichiometric mode. The investigation was carried out at part-load operating conditions, with early injections during the intake stroke. It included three engine speeds at fixed engine-equivalent load. The spray model was calibrated using test-bed and imaging data from the 7-point high-pressure fuel injectors used in the test engine.

Soot formation and distribution inside the cylinder of a light-duty direct injection diesel engine, have been predicted using Kiva-3v CFD software. Pathlines of soot particles traced from specific in-cylinder locations and crank angle instants have been explored using the results for cylinder charge motion predicted by the Kiva-3v code. Pathlines are determined assuming soot particles are massless and follow charge motion. Coagulation and agglomeration have not been taken into account. High rates of soot formation dominate during and just after the injection. Oxidation becomes dominant after the injection has terminated and throughout the power stroke. Computed soot pathlines show that soot particles formed just below the fuel spray axis during the early injection period are more likely to travel to the cylinder wall boundary layer. Soot particles above the fuel spray have lesser tendency to be conveyed to the cylinder wall.