Evaporation Characteristics of Fuels for Low Temperature Combustion Engine Applications 2021-01-1210

The research on reducing emissions from automotive engines through modifications in the combustion mode and the fuel type is gaining momentum because of the increasing contribution to global warming by the transportation sector. The combustion and emission formation in the advanced low temperature combustion (LTC) engine strategies are susceptible to fuel molecular composition and properties. Ignition timing in LTC strategies is primarily controlled by fuel composition and associated chemical kinetics. Thus, tailoring of fuel properties is required to address the limitations of LTC in terms of lack of control on ignition timing and narrow engine operating load range. Utilizing fuel blends and additives such as nanoparticles is a promising approach to achieving targeted fuel property. An improved understanding of fundamental processes, including fuel evaporation, is required due to its role in fuel-air mixing and emission formation in LTC. In the present work, evaporation characteristics of blends of commercial fuels, viz. gasoline, diesel and alternative fuels, viz. ethanol and butanol are investigated. Further, graphene-based nano additives at 0.05 wt % in gasoline, diesel and butanol are also investigated. There are several research studies available on the evaporation rate characteristics of different fuels under conventional combustion conditions. The present work is intended to understand the evaporation rate behaviour of different fuels under typical LTC conditions. The outcomes of such fundamental studies would allow a careful choice of fuels for LTC engine applications. The important engine fuel properties viz. density, viscosity, surface tension for 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 following the base fuel proportion, while the changes are insignificant with nanoparticle addition. The evaporation rate study reveals that the fuel type strongly influences the changes in fuel evaporation rate, viz. a 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 improve the evaporation rates of fuel blends significantly.