Low octane fuel composition effects on the load range capability of partially premixed combustion

To determine the influence of physical and chemical properties of fuels’ load range capacity in partially premixed combustion, seven fuels have been blended, with a fixed RON70 reactivity. Four of these fuels are blended from refinery streams, with different boiling ranges, aromatic- and bio-content. Furthermore, three ternary mixtures of Toluene, n-Heptane, Ethanol and iso-Octane are used, of which the aromatics (toluene) and oxygenate (ethanol) content are varied. The load range capacity of these fuels is determined based on their fuel efficiency, smoking tendency and its sensitivity to the fuel pressure used, nitrogen oxides emissions, and combustion efficiency and stability at low load and engine speed

Optimizing engine efficiency by balancing dilution, heat release rate and combustion phasing

In this investigation highly diluted engine tests have been conducted to study effects of dilution, heat release rate and combustion phasing on both efficiency and emissions in the Partially Premixed Combustion regime. It has been reported that over the complete phasing range an increase of more than two percent points in indicated efficiency at high load could be expected, with an astonishing 4 to 5 percent points for the low load case. The origins of these increases were sought and found to be caused by improved heat release shapes, combustion efficiencies or heat losses or a combination of these. On the other hand, soot emissions are greatly reduced due to the excess oxygen available, but nitrogen oxide emissions are found to increase: both in concentration and power specific units