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The blending of oxygenated compounds with gasoline is projected to increase because oxygenate fuels can be produced renewably, and because their high octane rating allows them to be used in substitution of the aromatic fraction in gasoline. Blending oxygenates with gasoline changes the fuels' properties and can have a profound affect on the distillation curve, both of which are known to affect engine-out emissions. In this work, the effect of blending methanol and ethanol with gasoline on unburned hydrocarbon and particulate emissions is experimentally determined in a spray guided direct injection engine. Particulate number concentration and size distribution were measured using a Cambustion DMS500. These data are presented for different air fuel ratios, loads, ignition timings and injection timings. In addition, the ASTM D86 distillation curve was modeled using the binary activity coefficients method for the fuel blends used in the experiments.

The burn rate and the instantaneous in-cylinder heat transfer have been studied experimentally in a spray-guided direct-injection spark-ignition engine with three different fuels: gasoline, iso-octane and toluene. The effects of the ignition timing, air fuel ratio, fuel injection timing and injection strategy (direct injection or port injection) on the burn rate and the in-cylinder heat transfer have been experimentally investigated at a standard mapping point (1500 rpm and 0.521 bar MAP) with the three different fuels. The burn rate analysis was deduced from the in-cylinder pressure measurement. A two-dimensional heat conduction model of the thermocouple was used to calculate the heat flux from the measured surface temperature. An engine thermodynamic simulation code was used to predict the gas-to-wall heat transfer.

Particulate Matter (PM) legislation for gasoline engines and the introduction of gasoline/ethanol blends, make it important to know the effect of fuel composition on PM emissions. Tests have been conducted with fuels of known composition in both a single-cylinder engine and V8 engine with a three-way catalyst. The V8 engine used an unleaded gasoline (PURA) with known composition and distillation characteristics as a base fuel and with 10% by volume ethanol. The single-cylinder engine used a 65% iso-octane - 35% toluene mixture as its base fuel. The engines had essentially the same combustion system, with a centrally mounted 6-hole spray-guided direct injection system. Particle size distributions were recorded and these have also been converted to mass distributions. Filter samples were taken for thermo-gravimetric analysis (TGA) to give composition information. Both engines were operated at 1500 rpm under part load.

A single-cylinder Gasoline Direct Injection Engine (GDI) engine with a centrally mounted spray-guided injection system (150 bar fuel pressure) has been operated with stoichiometric and rich mixtures. The base fuel was 65% iso-octane and 35% toluene; hydrogen was aspirated into a plenum in the induction system, and its equivalence ratios were set to 0, 0.02, 0.05 and 0.1. Ignition timing sweeps were conducted for each operating point. Combustion was speeded up by adding hydrogen as expected. In consequence the MBT ignition advance was reduced, as were cycle-by-cycle variations in combustion. Adding hydrogen led to the expected reduction in IMEP as the engine was operated at a fixed manifold absolute pressure (MAP). An engine model has also been set up using WAVE. Particulate Matter (PM) emissions were measured with a Cambustion DMS500 particle sizer.

Tax concessions promote the use of Liquefied Petroleum Gas (LPG) fuel for automotive use in Europe. Modelling of the LPG evaporation process shows the importance of drawing the liquid from the tank rather than the gas, otherwise the most volatile component (propane) is used more quickly and the composition of the remaining fuel changes. It is shown that the LPG components have similar calorific values to gasoline, however injecting the LPG as a gas into the inlet port causes a loss of volumetric efficiency and peak power. The experimental results showed: The LPG fuels have similar burn rates and optimum ignition timing to gasoline. The Lean Mixture Limit (LML) of the gaseous fuels was weaker than that for gasoline.

Knocking combustion places a major limit on the performance and efficiency of spark ignition engines. Spontaneous ignition of the unburned air-fuel mixture ahead of the flame front leads to a rapid release of energy, which produces pressure waves that cause the engine structure to vibrate at its natural frequencies and produce an audible ‘pinging’ sound. In extreme cases of knock, increased temperatures and pressures in the cylinder can cause severe engine damage. Damage is thought to be caused by thermal strain effects that are directly related to the heat flux. Since it will be the maximum values that are potentially the most damaging, then the heat flux needs to be measured on a cycle-by-cycle basis. Previous work has correlated heat flux with the pressure fluctuations on an average basis, but the work here shows a correlation on a cycle-by-cycle basis. The in-cylinder pressure and surface temperature were measured using a pressure transducer and eroding-type thermocouple.