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High-speed laser diagnostics was utilized for single-cycle resolved studies of the formaldehyde distribution in the combustion chamber of an HCCI engine. A multi-YAG laser system consisting of four individual Q-switched, flash lamp-pumped Nd:YAG lasers has previously been developed in order to obtain laser pulses at 355 nm suitable for performing LIF measurements of the formaldehyde molecule. Bursts of up to eight pulses with very short time separation can be produced, allowing capturing of LIF image series with high temporal resolution. The system was used together with a high-speed framing camera employing eight intensified CCD modules, with a frame-rate matching the laser pulse repetition rate. The diagnostic system was used to study the combustion in a truck-size HCCI engine, running at 1200 rpm using n-heptane as fuel. By using laser pulses with time separations as short as 70 μs, cycle-resolved image sequences of the formaldehyde distribution were obtained.

A major trend in current automotive research is hybridization of the power supply. This combination of electrical machine and combustion engine results, in some hybridization topologies, in a total decoupling of the combustion engine from the transmission. When the engine is decoupled from the transmission a new degree of freedom arises in engine design. The piston movement does not have to follow an evenly rotating shaft any more. It can be altered by the generator to achieve a movement found to be better from the point of efficiency or environmental concerns. Modelling work showed a potential of lowered NO emissions if the expansion could be delayed. The experimental study, conducted in a two piston Alvar engine, showed that the state of the art electrical machine (EM) propelling one of the crankshafts was too weak to change the crankshaft speed in an extent to give the fast volume changes required to change the emissions of the internal combustion engine (ICE).

A naturally aspirated in-line six-cylinder 2.9-litre Volvo engine is operated in Homogeneous Charge Compression Ignition (HCCI) mode, using camshafts with low lift and short duration generating negative valve overlap. Standard port fuel injection is used and pistons and cylinder head are unchanged from the automotive application. HCCI through negative valve overlap is recognized as one of the possible implementation strategies of HCCI closest to production. It is important to gain knowledge of the constraints and limits on the possible operating region. In this work, the emphasis is on investigating how cycle-to-cycle and cylinder-to-cylinder deviations limit the operating region, how these effects change in different parts of the operating region and how they can be controlled. At low load the cycle-to-cycle phenomena cause periodic behavior in combustion timing; together with cylinder deviations this is found responsible for decreasing the operating regime.

HCCI (Homogeneous Charge Compression Ignition), laser-assisted HCCI and spark plug-assisted HCCI combustion was studied experimentally in a modified single cylinder truck-size Scania D12 engine equipped with a quartz liner and quartz piston crown for optical access. The aim of this study was to find out how and to what extent the spark, generated to influence or even trigger the onset of ignition, influences the auto-ignition process or whether primarily normal compression-induced ignition remains prevailing. The beam of a Q-switched Nd:YAG laser (5 ns pulse duration, 25 mJ pulse energy) was focused into the centre of the cylinder to generate a plasma. For comparison, a conventional spark plug located centrally in the cylinder head was alternatively used to obtain sparks at a comparable location. No clear difference in the heat releases during combustion between the three different cases of ignition start could be seen for the fuel of 80/20 iso-octane/n-heptane used.