EFFECTS OF BLENDING OF FUELS ON THEIR. IGNITION QUALITY AND PERFORMANCE IN C. I. ENGINES

Abstract

In compression-ignition engines there is always some time lag between the point of injection and start of burning of fuel which is known as "Ignition delay". The magnitude of this delay governs, to a large measure, the subsequent performance of the fuel In the engine. Generally speaking, we endeavour to reduce the ignition delay as much as possible. The effect of blending of fuels on their ignition quality were studied at different operating conditions of the engine by means of their ignition delay. Secondary reference fuels were used as a standard of comparision for different blends. Pressure-time diagrams were recorded to study he performance of the engine. Data obtained with diesel-Petrol blends at various operating conditions of the engine, indicate that the delay angle of the blend increases as the percentage of petrol in the blend increases. Thus the addition of petrol deteriorates the ignition quality of diesel fuel although, under some conditions, the engine runs smoother and quieter. The addition of lubricating oil in diesel as well as petrol, however, improves their ignition behaviour, but this improvement is at the cost of carbon deposit on the cylinder walls. Addition of diethyl ether to diesel fuel increases the °steno number slightly. Amyl-nitrate has been shown to be as a good ignition accelerator for both diesel-as well as petrol. Manifold introduction of petrol did'not show any improlfe-ment in the ignition quality of pure diesel, while diethyl ether shoved considerable improvement• On the basis of the experimental data a correlation relating the pressure and temperature of intake air, the effective compression ratio at the point of injection, the cotano nuttier of the fuel and the ignition delay has been proposed. The results from this correlation are compared with those obtained on CFR engine by other investigators, and it has been shown that the difference is very small. Further, it has been shown that this correlation has a wide range of application.