Gasoline partially premixed combustion,the future of internal combustion engines?

Gasoline partially premixed combustion showed the potential of very high efficiency, emissions of nitrogen oxides (NO _x ) and soot below future emission regulations, and acceptable acoustic noise from idle up to 26 bar gross indicated mean effective pressure. For instance, gross indicated efficiencies in the range of 53 to 55 per cent were achieved in the whole load range keeping NO _x below 0.30 g/kWh, soot below 0.30 filter smoke number (FSN), and relative maximum pressure rise rate below 8 bar/crank angle degree. The goal was achieved by developing an appropriate EGR–λ (exhaust gas recirculation/relative excess of air) combination and an advanced injection strategy, and by making minor modifications to the engine layout.

The current paper presents a summary of the advantages of using gasoline-type fuels (research octane number (RON) from 80 to 69) in a heavy-duty compression ignition engine. Low-octane-number gasoline fuels were chosen because they can run from idle to maximum load without any major modification to the engine layout and because low-load operations are achievable even when the engine is cold and the inlet temperature is low. Experiments were carried out in two single-cylinder engines, Scania D12 and Scania D13, using a total of three different engine setups. The influence of different types of gasoline (RON from 99 to 69) on this novel combustion concept was analysed. A comparison between gasoline and diesel fuels is presented and the viability of reaching 50 per cent brake efficiency while keeping low emissions of NO _x and soot is shown.