Enhancing Low Temperature Combustion Through the Application of Alcohol Blends

Future road transportation requires innovative propulsion technologies to address the environmental issues associated with internal combustion engines. Low temperature combustion (LTC) is a new, highly investigated technology capable of simultaneously reducing nitrogen oxide and particulate matter emissions. However, the low combustion temperature in LTC can impair oxidation, limiting its effectiveness under various operating conditions. This paper aims to investigate the effects of oxygenates, particularly alcohols, on LTC to mitigate oxidation difficulties. To demonstrate the effects of alcohols, modulated kinetics (MK) type LTC was achieved in an unmodified diesel engine by applying high rates of low-pressure exhaust gas recirculation at three different loads at 1250 rpm. The combustion and emission characteristics of the engine were evaluated during MK operation using a diesel reference fuel, a diesel-alcohol blend with 30% ethanol, and another diesel-alcohol blend with 30% 2-ethylhexanol. Both alcohols reduced particulate matter emissions and enabled a higher LTC operating range. It was concluded that introducing oxygenated fuels could be advantageous when commercial vehicles utilizing LTC become prevalent, as new combustion technologies necessitate fuels with specific characteristics for optimal performance.