Impact of engine control on the energetic inter change ability of diesel oil by gas in dual fuel GI engine

A compression ignition engine fuelled simultaneously with two fuels: a fuel with low cetane number used as the main fuel, and Diesel oil used to initiation of ignition, is assumed to be called as a dual fuel engine. This system is perfectly suited to adaptation to supply of CNG gas in majority of compression ignition engines. Such adaptations can concern both an older engine equipped with classic injection system, and modern engine with common rail system. In traction engines, interchangeability of liquid fuel by the gas belongs to important issues, what is a condition of profitability of the adaptation and operation of dual fuel engines. In the paper are presented test results of the 1CA90 engine with piston pump to injection of liquid fuel, and a system with mixer to supply of the gas; and the SB3.1 engine equipped with common rail system and injection of the gas in area of the inlet valve. On the base of performed tests one has shown variability of energetic fraction of the CNG gas in total energy supplied to the engine. The tests were performed in complete field of variability of engine parameters, i.e. rotational speed and engine load. Obtained results have shown that in spite of decreasing fraction of the gas at partial loads of medium size traction engines, substantial reduction of operational consumption of the Diesel oil is possible. Due to significant differences in price of the CNG gas and the Diesel oil, it gives considerable savings in operational costs of the engines. It should encourage users of the engines to adaptation of the fuelling to the CNG gas. In the paper is presented a proposal of control system to dual fuel traction engine, from maintaining its performance parameters point of view.