Combustion and Emissions in an HSDI Engine Running on Diesel or Vegetable Oil Base Fuel with n-Butanol or Diethyl Ether As a Fuel Extender

Abstract

The present investigation compares the combustion, performance, and exhaust emissions of diesel fuel in blends with either 24% $n$-butanol or 24% diethyl ether (DEE), and of vegetable (cottonseed) oil in blends with either 20% $n$-butanol or 20% diethyl ether, fueling a standard, experimental, single-cylinder, four-stroke, high-speed direct injection (HSDI), Hydra diesel engine operated at three different loads. Fuel consumption, and exhaust smoke, nitrogen oxides (NOx), carbon monoxide (CO), and total unburned hydrocarbons (HC) were measured. The differences in combustion, performance, and exhaust emissions of those biofuel blends are compared from the baseline operations, i.e., when working with the neat base fuels (diesel fuel or vegetable oil). Fuel injection, combustion chamber pressure, heat release rate, and temperature diagrams, reveal interesting features of the combustion mechanisms. These results and the differing physical and chemical properties of those biofuels are used to aid the interpretation of the observed engine behavior. Using $n$-butanol or diethyl ether as fuel extenders to either diesel fuel or vegetable oil (base fuels), reductions of smoke and NOx, decrease of CO, and increase of HC emissions are observed, against the corresponding neat base fuel cases.