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Wet ethanol is a low cost renewable fuel which often shows challenging ignition in spark-ignited engines. This can be tackled by using non-flame propagating combustion modes like HCCI. This paper shows experimental results of a diesel fueled generator set which recovers exhaust heat from one of the diesel cylinders to promote HCCI of ethanol on other cylinders. Experimental tests provided results of heat release, energy efficiency and a thorough combustion analysis that demonstrate the possibility of this concept which requires minimal changes on the original engine, making possible to retrofit existing units. A three-cylinder four-stroke engine originally fueled with diesel was used. The diesel injection system in one of the cylinders was replaced by an ethanol electronic fuel injection. Inlet heat for achieving HCCI was provided by complete exhaust recycling from one of the diesel cylinders. Stable HCCI combustion was achieved in the ethanol cylinder.

Ethanol with high levels of hydration is a low cost fuel that offers the potential to replace fossil fuels and contribute to lower carbon dioxide (CO2) emissions. However, it presents several ignition challenges depending on the hydration level and ambient temperature. Advanced combustion concepts such as homogeneous charge compression ignition (HCCI) have shown to be very tolerant to the water content in the fuel due to their non-flame propagating nature. Moreover, HCCI tends to increase engine efficiency while reducing oxides of nitrogen (NOx) emissions. In this sense, the present research demonstrates the operation of a 3-cylinder power generator engine in which two cylinders operate on conventional diesel combustion (CDC) and provide recycled exhaust gas (EGR) for the last cylinder running on wet ethanol HCCI combustion. At low engine loads the cylinders operating on CDC provide high oxygen content EGR for the dedicated HCCI cylinder.