Experimental investigation in diesel fuel, rapeseed oil and its blend combustion in off-road diesel engines.

The paper presents comparative analysis of the combustion and emission characteristics of rapeseed oil (RO) and blends of 25 %, 50 % and 75 % of rapeseed oil in diesel fuel for different engine load and speed conditions. The stand tests were performed on a four-stroke, four-cylinder, direct injection, naturally aspirated diesel engine D-243. The in-cylinder pressure data were analysed to extract the heat release rate, ignition delay, in-cylinder pressure peak and maximum in-cylinder pressure rate. The influence of rapeseed oil amount in the fuel on the exhaust emission and brake specific fuel consumption were also investigated. The bench testing results show that when the engine was running at 1400 min -1 at low and full loads auto-ignition delay was longer by 4.2 % and 2.1 % respectively compared to the auto-ignition delay while running on diesel fuel. The in- cylinder pressure peak and pressure rise rate while operating at full and moderate load increases with the increase of the amount of rapeseed oil in fuel. While the engine was operating at low the load in-cylinder pressure peak and pressure rise rate decreases when increasing the amount of rapeseed oil in fuel. The brake specific fuel consumption of the fully loaded engine running on 100 % RSO increased by 17 % and 22 % at 1400 min -1 and 2200 min -1 speeds respectively when compared to that of diesel fuel. The brake thermal efficiency decreased at the same operating conditions only by 1.6 % and 5.5 % respectively. When the engine was running on rapeseed oil NO x, unburned HC emissions and the exhaust opacity decreased, CO emissions increased.