Comparative investigations on exhaust emissions of insulated diesel engine and conventional diesel engine with biogas

There is a tremendous rate of exhaustion of fossil fuels due to increase of demand with the use of them in transport sector and agricultural sector, escalation of fuel prices in International Oil Market causing huge investment of foreign exchange, which otherwise can be spent on important sectors like health, education, poverty, defense etc., increase of environmental problems like Global warming and Green-house effect with IC engine with the use of fossil fuels, the search for alternative fuels has become necessary and pertinent. The vegetable oils and alcohols are important substitutes for diesel fuels, as they are renewable. However, drawbacks associated with vegetable oils (high viscosity and low volatility) and alcohols (low cetane number {measure of combustion quality} and calorific value) cause combustion problems in diesel engines. Most of the alcohol produced in India, is diverted to petro-chemical industries. Vegetable oils are converted into biodiesel, as biodiesel have moderate viscosity and contain oxygen in their molecular composition. However, these biodiesels call for low heat rejection (LHR) engines, as these engines are suitable for low calorific value and high viscous fuels, due to high heat release rate and give faster rate of combustion. Gaseous fuels have many advantages than liquid fuels, as their calorific values of fuels are high, pollutants emitted by gaseous fuels are low and less dangerous when compared with liquid fuels. They are many methods to induct gaseous fuels such as port injection, carburetion technique, injection of gaseous fuel at the near end of compression stroke etc,. Investigations were carried out with biogas gas as primary fuel inducted by port injection and cottonseed biodiesel was injected into the engine in conventional manner. 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 combustion chamber of LHR engine was made of ceramic coated cylinder head. The pollutants of PM, NOx, CO and UBHC were determined at full load operation of the engine with varied injection pressure and compared with conventional engine (CE) with diesel and biodiesel operation. The maximum induction of biogas was 35% in CE, while it was 45% in LHR engine of total mass of biodiesel as full load operation. Particulate emissions were determined by AVL Smoke meter, while other emissions were measured by Netel Chromatograph multi-gas analyzer at full load operation. These pollutants were drastically reduced with induction of biogas and further reduced with an increase of injection pressure. LHR engine considerably reduced pollutants in comparison with CE, with biogas operation.