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Homogenous Charge Compression Ignition (HCCI) is an alternative to Spark Ignited (SI) combustion, which can provide part-load efficiencies as high as compression ignition engines and energy densities as high as SI engines, without high levels of NOx or Particulate Matter (PM). The principle of operation involves reaching the thermal oxidization barrier of a homogeneous air-fuel mixture. This combustion practice is enabled by diluting then compressing the mixture with the Trapped Residual Gases (TRG) to dilute the initial charge thus keeping combustion temperatures down. Introduction of exhaust gasses in the mixture can be achieved by the use of early exhaust valve closure and late inlet valve opening. The charge is well mixed avoiding particulate emissions, and by using exhaust gasses for load regulation the need for throttled operation is removed allowing the realization of high efficiencies, low pumping losses and a resulting 15 - 20% improvement in fuel economy.

A dual fuel engine is an internal combustion engine where the primary gaseous fuel source is pre-mixed with air as it enters the combustion chamber. This homogenous air fuel mixture is ignited by a small quantity of diesel known as the ‘pilot’ that is injected towards the end of the compression stroke. The diesel fuel ignites in the same way as in compression ignition (CI) engines, and the gaseous fuel is consumed by flame propagation in a similar manner to spark ignited engines. The motivation to dual-fuel a CI engine is partly economic due to the lower cost of the primary fuel, and partly environmental as some emissions characteristics are improved. In the present study, a direct injection four cylinder CI engine, typically used in genset applications, was fuelled with three different gaseous fuels; methane, propane and butane.

Methyl esters derived from vegetable oils by the process of transesterification (commonly referred as ‘biodiesel’), can be used as an alternative fuel in compression ignition engines. In this study, three different vegetable oils (rape, soy and waste oil) were used to produce biodiesel fuels that were then tested in a four cylinder direct injection engine, typically used in small diesel genset applications. Engine performance and emissions were recorded at five load conditions and at two different speeds. This paper presents the results obtained for measurements of NOx and smoke opacity at the different speed and load conditions for the three biodiesels, and their blends (5 and 50% v/v) with mineral diesel. A simple combustion analysis was also performed where ignition delay, position and magnitude of peak cylinder pressure and heat release rate were examined to asses how the variation of chemical structure and blend percentage affects engine performance.

A novel gas fuel injector system based on the use of monostable fluidic devices is described in this paper. The proposed system consists of non-moving-part fluidic devices which are capable of operating in a Pulse Width Modulated (PWM) control mode and of handling a large amount of gas flow for engine operations. The system also includes an electro-fluidic interface for fluidic switching and air-gas mixing nozzles for better mixing quality. Two prototype fluidic injector units were produced and their steady-state and dynamic characteristics were evaluated on a laboratory test rig. The results were compared with those from several commercial gas injectors and it was found that the fluidic injector has a faster dynamic response and a smaller cycle-cycle variations.