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Ethanol as a renewable fuel is employed in either the hydrated or anhydrous states. The production of anhydrous ethanol requires an additional and costly processing step, and is less advantageous with regard to Life Cycle Inventory. The use of hydrated ethanol may then be preferred for high blend and pure fuels, and future engine technologies designed for ethanol may need to accommodate either form. In the current study a spark ignited ethanol direct injection (EDI) turbocharged engine, proposed for efficient delivery of high specific output, is evaluated for performance at high load with anhydrous and hydrated ethanol as fuel. Test data show the EDI engine may be operated at high load on either fuel with the same output and efficiency. The key differences arising from fuel water content are reduced burn rate requiring advance in ignition timing, a decrease in engine emissions of NOx and increase of HC, and higher potential for increase of compression ratio and output.

A study has been undertaken on a boosted single cylinder research engine with direct injection of hydrogen. In order to reduce NOx emissions and tendency to knock, efforts have been made to reduce the temperatures and rate of heat release during combustion. Lean boosted operation, stoichiometric operation with exhaust gas recirculation, and water injection using a dual fluid direct injector were investigated and NOx emissions, thermal efficiency, and combustion stability were compared. Conclusions are developed for specific power optimisation and NOx management which may be applied for hydrogen fuelling of small general purpose through to heavy duty engines.