On the Ignition Performance of Some Coal Derived Diesel Engine Fuels

In this work, the thermal ignition delay of some coal-derived liquid fuels and their blends with Phillips D-2 diesel fuel was measured. For this purpose, a shock-tube test set up was designed and manufactured. It was fully instrumented for delay measurement with piezo-electric pressure transducers, charge amplifiers, storage oscilloscope and electronic plotter. The test variables included the type of fuel, equivalence rlatio, ignition pressure and ignition temperature. It was found that coal-derived fuels exhibit a longer ignition delay than light diesel fuel, primarily because of its higher aromatic content. Rich and lean mixtures produce long delay whilst the minimum delay occurred at the stoichiometric mixture. Higher ignition pressures and temperatures reduced the delay. The fuels that were considered suitable for high speed engines were singled out; also those suitable for medium and slow speed engines were put forward. A correlation was developed to predict the data which read:

Arrhenius plots were made to evalaute the activation energy of each test fuel.