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Ethanol as a renewable fuel has been used widely in vehicles. Dual fuel injection is one of the new techniques in development for increasing the engine’s thermal efficiency and reducing the pollutant emissions. This study reports experimental investigation to the dual ethanol fuel injection with a focus on the effect of spark timing on the engine performance at different volumetric ratios of ethanol directly injected to ethanol port injected. Experiments were conducted on a single cylinder 250cc spark ignition engine at two engine loads and 3500 RPM. The spark timing was varied from 15 to 42 CAD bTDC at the light load and from 15 to 32 CAD bTDC at the medium load, while the volumetric ratio of direct injection (DI%) was varied from 0% to 100%.

Ethanol direct injection plus gasoline port injection (EDI+GPI) is a new technology to make the use of ethanol fuel more effective and efficient in spark ignition engines. It takes the advantages of ethanol fuel, such as its greater latent heat of vaporization than that of gasoline fuel, to enhance the charge cooling effect and consequently to increase the compression ratio and improve the engine thermal efficiency. Experimental investigation has shown improvement in the performance of a single cylinder spark ignition engine equipped with EDI+GPI. It was inferred that the charge cooling enhanced by EDI played an important role. To investigate it, a CFD model has been developed for the experimentally tested engine. The Eulerian-Lagrangian approach and Discrete Droplet Model were used to model the evolution of the fuel sprays. The model was verified by comparing the numerical and experimental results of cylinder pressure during the intake and compression strokes.

Ethanol has been used either as an alternative fuel or in blends with gasoline in spark ignition (SI) engines for many years. However, the existing method of using ethanol fuel by blending gasoline and ethanol fuel does not fully exploit the ethanol fuel's potential in improving engine thermal efficiency and reducing pollutant emissions. The dual-fuel injection strategy, ethanol direct injection plus gasoline port injection (EDI+GPI), offers a potentially new way to make the best use of ethanol fuel. In this paper the potential of EDI+GPI is investigated based on experiments conducted on a single cylinder SI research engine equipped with EDI+GPI. The leveraging effect of EDI+GPI on engine performance was investigated at different ethanol/gasoline energy ratios (EERs) and speeds. Then further investigation to the leveraging effect enhanced by ethanol injection timing and spark timing was performed. Experimental results showed that the IMEP increased with the increase of EER.

The work reported in this paper contributes to understanding the effects of ethanol/gasoline ratio on mixture formation and cooling effect which are crucial in the development of EDI+GPI engine. The spray simulations were carried out using a commercial CFD code. The model was verified by comparing the numerical and experimental results of spray shapes in a constant volume chamber and cylinder pressure in an EDI+GPI research engine. The verified model was used to investigate the fuel vaporization and mixture formation of the EDI+GPI research engine. The effect of the ethanol/gasoline ratio on charge cooling has been studied. Compared with GPI only, EDI+GPI demonstrated stronger effect on charge cooling by decreased in-cylinder temperature. However, the cooling effect was limited by the low evaporation rate of the ethanol fuel due to its lower saturation vapour pressure than gasoline's in low temperature conditions.

Ethanol direct injection plus gasoline port injection (EDI+GPI) is a new technical approach to make the use of ethanol fuel more effective and efficient in spark ignition (SI) engines. Ethanol fuel direct injection timing, as one of the primary control parameters in EDI+GPI engines, directly affects the quality of the fuel/air mixture and consequently combustion and emissions. This paper reports the experimental investigation to the effect of ethanol injection timing and pressure on engine performance, combustion, emissions of a single cylinder SI engine equipped with EDI+GPI. Firstly, the effect of EDI timing before and after the inlet valve closing, defined as early and late injection timings (EEDI and LEDI) was investigated at three injection pressure levels of 40 Bar, 60 Bar and 90 Bar and a fixed ethanol/gasoline ratio. Spark timing was fixed at original engine setting to investigate the potential engine efficiency improvement due to the EDI solely.

Ethanol direct injection (EDI) is a new technology to use ethanol fuel more efficiently in spark ignition engines. Fuel temperature is one of the key factors which determine the evaporation process of liquid fuel spray, and consequently influence the combustion and emission generation of the engine. To better understand the mixture formation process of the EDI spray and provide experimental data for engine modelling, experiments were conducted in a constant volume chamber in engine-like conditions. The high speed Shadowgraphy imaging technique was used to capture the ethanol spray behaviours. The experiments covered a wide range of fuel temperature, ranged from 275 K (non-evaporating) to 400 K (flash-boiling). Particularly the transition of the ethanol spray from normal-evaporating to flash-boiling was investigated.