A sensor based assessment of ignition delay for pure diesel and biodiesel blends in an isochoric combustion box

The key to efficient operation of a diesel engine is the smooth combustion of the fuel and controlled detonation. In diesel engine detonation depends on ignition delay (ID) period. An isochoric cylindrical combustion box (CCB) is fabricated for the assessment of ID tendency for simple diesel and vegetable oils-diesel fuel blend (VODFB). The combustion box consist of air heating coils, hot surface plate, fuel injector, pressure gauge, temperature indictor, temperature controller and photo sensor. A two stage compressor with intercooler is used for charging the air in the combustion box. The ignition lag was measured for injection pressures (IP) (100-bar, 200-bar and 300-bar), hot surface temperatures (400°C and 450°C), cylinder pressures (10, 15, 20 and 25-bar) for simple diesel and VODFB by using photo sensor and scope-meter. The results show that ID was decreased with increase in IP, at a specific cylinder pressure and HST for both simple diesel and VODFB. At high IP (300-bar), ID is lower for the blended fuel because at high IP, the fuel covers more physical land and more fuel is vaporized within a given time period and hence ID time decrease.