Evaporation Characteristics of Fuels for Low-Temperature Combustion Engine Application

The research on reducing emissions from automotive engines through modifications in the combustion mode and the fuel type is gaining momentum because of increasing contribution to the global warming potential by the transport sector. The combustion and emission formation in the advanced low-temperature combustion (LTC) engine strategies are highly sensitive to the fuel molecular composition and its properties. As the ignition timing in LTC is primarily controlled by the fuel chemical kinetics, tailoring of fuel properties is required to address the limitations in-terms of lack of ignition timing control and a narrow operating load range. Utilizing fuel blends and additives such as nanoparticles are one of the promising approaches to achieve targeted fuel property. An improved understanding of fundamental processes including fuel evaporation is required owing to its role in fuel-air mixing and emission formation in LTC. In the present work, evaporation rate characteristics of blends of commercial fuels, viz. gasoline, diesel, and alternative fuels, viz. ethanol and butanol are investigated. Further, the effect of graphene-based nano additives at 0.05 wt % in gasoline, diesel, and butanol are also investigated. This study is intended to understand the fundamental behavior of different fuel options for LTC. The important engine fuel properties viz. density, viscosity, surface tension for all the test fuel samples are measured following ASTM standard test procedure. The evaporation rate studies are carried out by using the hanging droplet method. The results obtained show that the trends of the changes in gross fuel properties including density, viscosity and surface tension for the fuel blends are in accordance with the base fuel proportion, while the changes are insignificant with nanoparticle addition. The evaporation rate study reveals that the changes in fuel evaporation rate are strongly influenced by the fuel type, viz. multi-component or single component. Utilizing fuel blends is found to suppress the hydrophilic nature in the case of ethanol. Further, the addition of nanoparticles is found to significantly improve the evaporation rates of fuel blends.