Studies an exhaust emissions in semi-adiabatic compression ignition enginewith alternate fuels

Alcohols (ethanol and methanol) and a few non-edible vegetable oils are sho wing a great potential for replacing conventional diesel fuels quite effect ively. The low heat rejection semi-adiabatic compression ignition (C.I.) en gines are gaining prominence for adopting these alternate fuels. The major pollutants of the exhaust emissions of C.I. engines are oxides of nitrogen (NOx) and black smoke. When alcohols are used as alternate fuels, the pollu tants have to be checked specifically for aldehydes which are carcinogenic in nature. The pollution levels of black smoke, NOx and aldehydes emitted t hrough exhaust of engine are reported here on both conventional and insulat ed versions of C.I, engines with different proportions of ethanol-diesel an d methanol-diesel mixtures. The non-edible vegetable oils crude, and esteri fied jatropha and pongamia oils are used for total replacement of diesel fu el on both configurations of the engine. The NOx and smoke levels have been found to be lower with both ethanol and methanol induction with both conve ntional and insulated versions of the engine in comparison to pure diesel o peration. Also, production of aldehydes in the form of formaldehyde has bee n found to increase with both ethanol and methanol operations. However, the insulated version of the engine with ethanol operation helps in reducing f ormaldehyde emissions of the engine. With the non-edible vegetable oils, ge neration of smoke is drastically increased in comparison to pure diesel ope ration. However, with preheating of vegetable oil and increased injection p ressure, the smoke levels get reduced and NOx levels increase marginally.