Direct Injection Diesel Engine
The physical and combustion properties of vegetable oils are close to petro-diesel fuel and in this context, vegetable oils can stand as an immediate candidate substitute for stored fuels. Vegetable oils are produced from processing of seeds of various plants and thus Renewable in nature. However due to inherent high viscosity and low volatility vegetable oils would pose problems such as fuel flow and poor atomization and constraining their direct use in engines without any modifications.
In the present investigation effect of supercharging is studied on the performance of a Direct Injection Diesel Engine with the use of untreated cottonseed oil. Performance of the engine is evaluated in terms of break specific fuel consumption, exhaust Gas Temperature and smoke Density. It is observed that when cottonseed oil is used as a fuel, there is a reduction in BSFC of about 15% when the engine is run at the recommended injection pressure and supercharging pressure of 0.4 bar g in comparison with the engine operation run under naturally operated condition.
Vegetable oils are mixtures of fatty acids-molecules that contain carbon, hydrogen, and oxygen atoms. The fatty acids present in it may be saturated, mono-unsaturated, or poly-unsaturated. The greater the number of the double bonds, the more easily the compound reacts with oxygen from the air and goes bad, as kitchen fats and oils do after months on the shelfs.
Intensive search is being carried out in developing diesel engine fuels and lubricants based on vegetable oils. Due to high viscosity of vegetable oils, they interfere with fuel jet penetration, atomization and results in higher fuel consumption and leaves gummy deposits on the engine components upon combustion.