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A laser sheet imaging system with Mie-scattering and Laser Induced Fluorescence (LIF) was used to investigate the spray characteristics of gasoline, methanol and ethanol fuels. A range of conditions found in today's gasoline engines were investigated including that observed during engine cold-start. Both a swirl injector and a multi-hole fuel injector were examined for each of the three fuels. A combination of the second harmonic (532 nm) and the fourth harmonic (266 nm) was generated simultaneously using a Nd:YAG laser system to illuminate the spray. The Mie-scattering technique was used to characterize the liquid phase of the spray while the LIF technique was used to detect a combination of liquid and vapor phases. While gasoline naturally fluoresced, the dopant TEA was added to the methanol and ethanol fuels as a fuel tracer. The Mie-scattering and LIF signals were captured simultaneously using a CCD camera along with an image doubler.

The ignition delay time of toluene reference fuels composed of iso-Octane, n-heptane and toluene was studied in a shock tube under the conditions of medium to high temperature ranges, different pressures (10-20 bar), and various equivalence ratios (0.5,1.0,1.5 and 2) by reflected waves.Three different ternary blends, TRF2 (42.8% iso-Octane/13.7% n-heptane/43.5% toluene), TRF3 (65% iso-Octane/10% n-heptane/25% toluene) and TRF4 (87.2% iso-Octane/6.3% n-heptane/6.5% toluene), with the same Research Octane Number of 95 (RON=95) were constructed. The experimental results showed that there was an obvious negative correlation between the ignition delay time of the toluene reference fuels and the pressure, temperature and equivalence ratio; and, a minimal discrepancy of TRF2, TRF3, and TRF4 was measured at pressures of 10 and 20 bar in a stoichiometric ratio. A detailed chemical mechanism was established to research the surrogate combustion properties.

Since 1992 some vehicles have experienced engine knock or rapping noise during cold starts that is caused by combustion chamber deposit interference (CCDI) To better understand the CCDI phenomena, engine dynamometer studies were conducted. Results show that base gasoline composition and detergent additive compositions have significant effects on combustion chamber deposit (CCD) build-up In addition to engine testing, thermogravimetric analysis (TGA) was used to determine a correlation between unwashed gum and CCD levels

A mini-dilution tube to measure particulate emissions is described and results obtained in an application are presented. The application selected is a study of fuel effects on stratified charge engine emission and combustion characteristics. The mini-dilution tube was developed to provide a capability for particulate measurements with dynamometer engines. The device has been demonstrated to yield particulate mass results agreeing to within 10 percent of those with a full scale tunnel in steady state tests with diesel powered vehicles. A PROCO engine modified by incorporation of Torch Ignition was used in the study. Fuels were a wide cut gasoline, methanol and Indolene Clear gasoline. The engine was operated at a speed of 1250 rpm with an indicated mean effective pressure of 390 kPa. Spark timing, injection timing, EGR and equivalence ratio were varied.

In-line hydrocarbon (HC) traps are not widely used to reduce HC emissions due to their limited durability, high platinum group metal (PGM) concentrations, complicated processing, and insufficient hydrocarbon (HC) retention temperatures required for efficient conversion by the three-way catalyst component. New trapping materials and system architectures were developed utilizing an engine dynamometer test equipped with dual Fourier Transform Infrared (FTIR) spectrometers for tracking the adsorption and desorption of various HC species during the light-off period. Parallel laboratory reactor studies were conducted which show that the new HC trap formulations extend the traditional adsorption processes (i.e., based on physic-sorption and/or adsorption at acid sites) to chemical reaction mechanisms resulting in oligomerized, dehydro-cyclization, and partial coke formation.

This paper studies the effect of cooled EGR on fuel consumption and anti-knock performance of a boosted port fuel injection (PFI) SI engine. Experimental results show that the cooled EGR increases the thermal efficiency by 2%∼18% depending on the operation conditions. Compared to low load operations, more improvements of the thermal efficiency are obtained at higher loads, primarily owing to the enhanced anti-knock performance, advanced combustion phasing, elimination of fuel-rich operations as well as reduced heat transfer loss with cooled EGR. The anti-knock performance of cooled EGR provides further potential to improve the thermal efficiency by increasing the compression ratio. To this end, a 1-D thermodynamic model of the engine is built and calibrated using the GT-Power code. A knock prediction correlation considering EGR is developed and validated with the experimental data.

An experimental study was conducted on the combustion and emissions characteristics of duel fuel sequential combustion (DFSC) mode on a single-cylinder engine, applying port injection of n-heptane combined with in-cylinder direct injection of commercial gasoline, ethanol and n-butyl alcohol, respectively. Three-stage combustion, which consists of low- and high-temperature combustion of premixed n-heptane and high temperature combustion of directly injected gasoline-like fuels were observed. The effects of the premixed ratio and overall heating values per cycle on the combustion characteristics and emissions were investigated. The experimental results show that: with the increasing of premixed ratio and overall heating values per-cycle, the ignition timing of the directly injected fuels advances and the maximum pressure and maximum mass-averaged temperature increase.