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An investigation has been performed of some of the characteristics of di-methyl ether (DME) during high pressure injection in a diesel fuel injection system with a single hole nozzle. Recent developments in the use of DME as an alternate fuel for diesel engines are discussed. The effects of fuel compressibility on compression work are compared for DME and typical hydrocarbon fuel components. Photographs of the transient injection process into room temperature Nitrogen are given for a range of chamber pressures. For a single hole injector, spray penetrations can be predicted using existing correlations for diesel fuel, provided DME fuel properties are used.

Assisted ignition and subsequent combustion of various fuels differing in volatility and viscosity in a Diesel engine is herein described. This study was conducted to investigate the feasibility of igniting low cetane fuels at the immediate vicinity of the nozzle orifice in an attempt to produce injection rate controlled heat release. Four fuels were studied: a high viscosity, low volatility Diesel blend, a low viscosity, high volatility Diesel blend, strait gasoline, and No.2 Diesel fuel which was used as a baseline for comparison purposes. A droplet ignition delay model was used to provide insight into the various physical processes that occur when heat release is controlled by rate of injection. Split injection timing predicted by the model resulted in the successful occurrence of rate controlled heat release for all of the fuels tested.

Dual fuel (CI) engines provide an excellent means of maintaining high thermal efficiency and power while reducing emissions, particularly in situations where the primary fuel does not exhibit good auto-ignition characteristics. This is especially true of diesel engines operating on natural gas; usually in stationary applications such as distributed power generation. However, because two fuels are needed, the reliability of the engine is compromised. Therefore, this paper describes the first phase of a project that is to eventually manufacture dimethyl ether (DME) from natural gas and supply it to the pilot injector of a dual fuel engine. A chemical pilot plant has been built and operated, demonstrating an intermediate step in the production of DME from natural gas. DME is manufactured from methanol for pilot injection into a dual fuel engine operating with natural gas as the main fuel.

In recent years, intensive research has been pursued throughout the world in order to find substitutes to crude oil based fuel in compression-ignition engines. Among the different fuels studied, methanol is probably the primary candidate to substitute diesel fuel in the future. The major problems encountered with methanol in diesel engines are its poor cold startability together with unstable combustion levels under low load. Forced ignition techniques such as glow plugs and spark plugs have been used to overcome these problems. The major disadvantages with the use of glow plugs are their high power requirements as well as their limited lifetime. This paper presents the results from recent work done on the feasibility of catalytically igniting methanol with the use of platinum and platinum/rhodium-coated glow plugs.

The effect of high pressure injection (using an accumulator type unit injector with peak injection pressure of approximately 20,000 psi, having a decreasing injection rate profile) on combustion was studied. Combustion results were obtained using a DDA Series 3–53 diesel engine with both conventional analysis techniques and high speed photography. Diesel No. 2 fuel and a low viscosity - high volatility fuel, similar to gasoline were used in the study. Results were compared against baseline data obtained with standard injectors. Some of the characteristics of high pressure injection used with Diesel No. 2 fuel include: substantially improved ignition, shorter ignition delay, and higher pressure rise. Under heavy load - high speed conditions, greater smokemeter readings were achieved with the high pressure injection system with Diesel No. 2 fuel. Higher flame speeds and hence, greater resistance to knock were observed with the high volatility low cetane fuel.

An experimental investigation of the ignition and combustion characteristics of two low cetane fuels in a spark assisted Diesel engine is described. A three cylinder Diesel engine was modified for single cylinder operation and fitted with a spark plug located in the periphery of the spray plume. Optical observations of ignition and combustion were obtained with high speed photography. Optical access was provided by a quartz piston crown and extended head arrangement. The low cetane fuels, a light end, low viscosity fuel and a heavy end, high viscosity fuel which were blended to bracket No. 2 Diesel fuel on the distillation curve, demonstrated extended operation in the modified Diesel engine. Qualitative and quantitative experimental observations of ignition delay, pressure rise, heat release, spray penetration and geometery were compared and evaluated against theoretical predictions.

An experimental investigation of the ignition and combustion characteristics of two low cetane fuels in a spark assisted diesel engine at cold starting conditions is described. A three cylinder diesel engine was modified for single cylinder operation and fitted with a spark plug located in the periphery of the fuel injection spray plume. Optical observations of ignition and combustion were obtained with high speed photography. Optical access was provided by a quartz piston crown and extended head arrangement. The low cetane fuels, a light end low viscosity fuel and a heavy end high viscosity fuel, which were blended to bracket No. 2 diesel fuel on the distillation curve, demonstrated extended operation at low temperature starting conditions in the modified diesel engine. Qualitative and quantitative experimental observations of fuel spray characteristics, ignition delay, pressure rise, heat release, and white smoke formation were compared and evaluated against theoretical predictions.