EXPERIMENTAL INVESTIGATIONS ON EXHAUST EMISSIONS OF DIESEL ENGINE FUELLED WITH CNG AND CARBURETED ETHANOL

In the scenario of fast depletion of fossil fuels, increase of fuel prices in International Market causing economic burden on developing countries like India and increase of pollution levels with fossil fuel, the search for alternative fuels has become pertinent. Gaseous fuels have many advantages than liquid fuels, as the pollutants emitted by gaseous fuels are low and less dangerous when compared with liquid fuels. Specifically, CNG, provides an affordable energy source. Not only is CNG cheaper, it also gives consumers fuel efficiency. Besides, CNG becoming a vehicle owner's best friend as it offers the potential of preserving the well-being of the vehicle, which translates into reduced up keeping cost. CNG is way better than petrol, as it emits less harmful gases such as carbon dioxide, carbon monoxide, hydrocarbons, nitrogen oxides and sulfur oxides into the air. Another big plus point about CNG is in abundant supply as it is widely available throughout the world. CNG was injected and ethanol was carbureted in diesel engine. Ethanol is highly volatile fuel and ratio of C/H (C=Number of carbon atoms, H=Number of hydrogen atoms in fuel composition) is less. However, ethanol has low cetane number. It causes combustion problems in diesel engine and hence call for semi adiabatic diesel engine (SADE), which can burn low calorific value fuel, give high heat release rate and faster rate of combustion. Air gap insulation was provided with piston and liner. Investigations were carried out with CNG as primary fuel inducted by port injection and ethanol was carbureted into the engine. Particulate matter (PM), oxides of nitrogen (NOx), carbon mono oxide (CO) levels and un-burnt hydro carbons (UBHC) are the exhaust emissions from a diesel engine. They cause health hazards, once they are inhaled in. They also cause environmental effects like Green-house effect and Global Warming. Hence control of these emissions is an immediate effect and an urgent step. The pollutants of PM, NOx, CO and UBHC were determined at different values of brake power of engine. Data was compared with diesel operation on conventional engine. The maximum induction of ethanol was 40% of total mass of diesel as full load operation, while it was 60% with SADE. Particulate emissions were determined by AVL Smoke meter, while other emissions were measured by Netel Chromatograph multi-gas analyzer at different values of brake power of the engine. These pollutants were drastically reduced with induction of CNG and carbureted ethanol and further reduced with SADE.