On the Ignition Delay of Jojoba Bio-Diesel and Its Blends with Gas Oil

Jojoba bio-diesel is one of the most promising bio-fuels to replace gas oil in diesel engines. Therefore, the main object of the present work was to measure and correlate the pressure rise ignition delay of jojoba bio-diesel and its blends with gas oil behind incident shock waves in a shock tube. For this purpose, a shock tube test set up was designed and manufactured. It was fully instrumented for delay measurement with two piezo-electric pressure transducers, dual mode charge amplifier, data acquisition card and a computer with suitable LabVIEW software. The test variables included the type of fuel (percentage of Jojoba bio-diesel in the blend with gas oil), equivalence ratio, ignition temperature and ignition pressure. It was found that jojoba bio-diesel exhibited a lower ignition delay in comparison with that of gas oil. Rich or lean mixtures produce long delays, whilst the minimum delay occurred near the stoichiometric mixture. Also, it was found that the ignition delay of jojoba bio-diesel blends with gas oil reduced considerably as the ignition temperatures and pressures increased. An analytical correlation was developed to predict the data. Such correlation predicted the data well, since the values of the measured and the calculated ignition delays were in good agreement. Moreover, the activation energy for each fuel was evaluated using Arrhenius plots.