STUDY OF CYCLE-TO-CYCLE VARIATION OF COMBUSTION PROCESS IN DIRECT INJECTION COMPRESSION IGNITION ENGINE OPERATING ON BIO-DIESEL

Abstract

The development of engine combining good fuel economy with low exhaust emissions has underlined the importance of engine pressure measurements. It has been observed that cylinder pressure varies cycle-by-cycle in a diesel engine, indicating there by, cycle-to-cycle variation in heat release, leading to cycle-to-cycle variations in the overall performance parameters viz: torque, thermal efficiency, soot formation, emission and noise emitted from the engine. In this work the cycle-to-cycle variation in the combustion process of a single cylinder four stroke, DI air-cooled, naturally aspirated variable speed, 5.59 kw diesel engine running on waste oil based biodiesel, diesel and their blends has been studied and combustion variation has been compared. The various parameter considered in the study are speed (3 level), load (3 level) and fuel type (diesel, B20, B40 and B 100).. The measuring set up consists of a piezo-electric pressure transducer with charge amplifier, crank angle encoder, TDC sensor, AVL Alpha-20 eddy current dynamometer and fast data acquisition system. The emission analysis was carried out using AVL 4000 light Di gas analyzer and AVL 437 Smoke meter was used for smoke density measurement. The pressure crank angle record has been obtained for 300 combustion cycles. The data for each operating conditions (speeds and loads) were analyzed for the maximum pressure, the maximum rate of pressure rise and indicated mean effective pressure. The cycle-to-cycle variation is expressed as the mean value, standard deviation, and coefficient of variation (COV) of these three parameters. COV of maximum pressure is almost same for all fuel blends with respect to speed at low load, but at higher load COV value is more for B40 at 2000rpm speed. The 20% bio-diesel blends (B20) was found to be the optimum concentration for blending and 100% bio-diesel (B 100) is almost similar to base fuel diesel at different speed-load combination with respect to COV of maximum pressure, maximum pressure rise rate and mean effective pressure. In addition pure bio-diesel fuel has shown less emission than that of base fuel diesel at any speed a