Effect of pilot fuel quantity on the performance of a dual fuel engine

It is well known that the operation of dual fuel engines at lower loads suf fers from lower thermal effciency and higher unburned percentages of fuel. To rectify this problem, tests have been conducted on a special single cyli nder compression ignition research engine (Ricardo E6) to investigate the e ffect of pilot fuel quantity on the performance of an indirect injection di esel engine fuelled with gaseous fuel. Diesel fuel was used as the pilot fu el and methane or propane was used as the main fuel which was inducted into the intake manifold to mix with the intake air. Through experimental inves tigations, it is shown that, the low efficiency and excess emissions at lig ht loads can be improved significantly by increasing the amount of pilot fu el, while increasing the amount of pilot fuel at high loads led to early kn ocking. (C) 1999 Elsevier Science Ltd. All rights reserved.