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Typical automotive emission testing systems usually employ Flame Ionization Detection (FID) analyzers to measure unburned fuel species in the exhaust, but the technique is not suitable for engines operating on alcohol fuels. The FID method is not sensitive to measuring unburned alcohol fuels due to the presence of oxygen bonds in the fuel molecule. Other techniques, such as Fourier Transform Infrared (FTIR), can provide accurate unburned fuel measurements with alcohol fuel. However, these techniques are expensive and are less accessible compared to FID analyzers. In this study, the unburned fuel emissions from the engine exhaust were measured simultaneously with FID and FTIR analyzers, with the engine operating on pure alcohols, which are methanol, ethanol, and n-butanol. While most previous work focuses on stoichiometric air-fuel mixtures, a wide range of lean operating conditions between global-λ 1.6 to 2.8 will be tested in this study.

This paper investigated the spray characteristics of methanol under the flash and non-flash boiling conditions defined by the Engine Combustion Network (ECN) Spray G. As a counterpart, the spray features of iso-octane were also simulated and compared to methanol. The Volume of Fluid (VOF) approach under the Eulerian scheme was employed to model the internal nozzle flow details, which information was used to initialize the spray parcels and taken as input for the Lagrangian simulations, namely, the one-way coupling method. Since the Eulerian high-fidelity simulations allow capturing the effects of the flow inside the non-symmetrical injector, the rate of injection (ROI) profile, discharge coefficient, and plume angle et al. are not required for the Lagrangian simulations. The simulation results show that the flash boiling led to longer penetrations and higher evaporation compared to the non-flash boiling condition for both fuels.

The purpose of present numerical study was to extend the operating range of alcohol (methanol and ethanol) fueled Homogeneous Charge Compression Ignition (HCCI) engine under low load conditions. Ignition of pure methanol and ethanol under HCCI mode of operation requires high intake temperatures and misfires at low loads are common in HCCI engines. Three methods have been adapted to optimize the use of methanol and ethanol for HCCI operation without increasing the intake temperature. First, blending methanol and ethanol with ignition improver, namely di-methyl ether (DME) and di-ethyl ether (DEE), was used to increase the cetane number and ignitability of premixed charge. Second, based on the blended fuels, the spark assistance was used to reduce required intake temperature for auto-ignition. Third, DME and DEE were directly injected to methanol and ethanol operated HCCI engine, in the form of Reactivity Controlled Compression Ignition (RCCI) combustion.