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The paper describes the design and operation of a laboratory combustion chamber used to measure the ignition delay times of diesel engine fuels at atmospheric pressure in near quiescent air. The flow apparatus has the means to provide air temperatures in the range between 650 and 730°K which is the typical temperature range at the end of the compression stroke in a diesel engine. An injection pump with a trigger mechanism delivers equal amounts of fuel to an injector, which sprays it into the constantly replensihed supply of fresh, hot air for combustion. An infrared radiation detector monitors the evolution of the temperature inside the combustion chamber. Ignition delay is measured as the time interval between the beginning of the needle lift and the beginning of increase in infrared radiation detected by the sensor. Test results for two fuels are presented and compared with the results from previous studies performed under similar test conditions.

The development of a fuel-air injection nozzle that injects a premixed fuel and air and then a quantity of clean air into the combustion chamber is described. The new injection nozzle provides better controllability of fuel-air mixing and fuel evaporation. Additionally, the clean air injection following the fuel-air mixture injection prevents stagnant fuel accumulations in the nozzle tip. Therefore, the fuel-air injection nozzle is of particular advantage for use with difficult fuels such as plant oils for long term operation. The fuel-air injection nozzle was tested in an engine running on sunflower oil giving significant reduction in carbon buildup. No engine modifications were necessary for the fuel-air injection nozzle installation.