International Journal of Soft Computing and Engineering (IJSCE) ISSN: 2231-2307, Volume-3, Issue-2, May 2013 22 Published By: Blue Eyes Intelligence Engineering & Sciences Publication Retrieval Number: B1420053213/2013©BEIESP Comparative Studies on Exhaust Emissions from a High Grade Low Heat Rejection Diesel Engine with Carbureted Alcohol and Crude Jatropha Oil V.V.R. Seshagiri Rao, T. Kishen Kumar Reddy M.V.S. Murali Krishna, P.V. Krishna Murthy Abstract—Investigations were carried out to study the exhaust emissions from high grade low heat rejection (LHR) diesel engine consisting of air gap insulated piston with 3-mm air gap with superni (an alloy of nickel) crown, air gap insulated liner with superni insert and ceramic coated cylinder head with normal temperature condition of crude jatropha oil and carbureted alcohol (ethanol / methanol) with varied injection timing and injection pressure and compared with methanol operation over ethanol operation and also with pure diesel operation on conventional engine (CE). Exhaust emissions of smoke and oxides of nitrogen (NOx) were recorded by AVL Smoke meter and Netel Chromatograph NOx analyzer respectively at different values of brake mean effective pressure (BMEP). Aldehydes were measured by dinitrophenyl hydrazine (DNPH) method at peak load operation of the engine. Smoke levels and NOx levels decreased by 47% 12% respectively with LHR engine at 27 o bTDC and at an injection pressure of 190 bar with methanol operation in comparison with pure diesel operation on CE. Index Terms— Crude Vegetable Oil, Methanol, Ethanol, CE, LHR engine, Emissions and Combustion characteristics. I. INTRODUCTION Following fuel crisis and vehicular population growth, search for renewable and alternate fuels has become pertinent for the engine manufacturers, users and researchers involved in the combustion research. Vegetable oils, which are renewable, have properties compatible to diesel fuels. Hence these fuels (straight vegetable oils, SVO) can be directly substituted in diesel engines without the modification of the engine. However, higher viscosity and chemical composition of unprocessed vegetable oils and fats have been shown [1] to cause problems in a number of areas (i) piston ring sticking; (ii) injector and combustion chamber deposits; (iii) fuel system deposits; (iv) reduced power; (v) reduced fuel economy and (vi) increased exhaust emissions due to high value of C/H ratio (C= Number of carbon atoms, H= Number of hydrogen atoms in fuel composition). Manuscript received May, 2013. V.V, R. Sesha giri Rao, Mechanical Engineering Department, Chaitanya Bharathi Institute of Technology Gandipet, Hyderabad,India. T.K.K. Reddy, Mechanical Engineering Department, J.N.T.U. College of Engineering, Kukatpally, Hyderabad,India. M.V.S. Murali Krishna, Mechanical Engineering Department, Chaitanya Bharathi Institute of Technology.India. P.V.K. Murthy, Mechanical Engineering Depaartment, Jaya Prakash Narayan Educational Society Group of Institutions, Bhageerath Colony, Mahabubnagar,India. Rudolph Diesel, [2] the inventor of the diesel engine that bears his name, experimented with fuels ranging from powdered coal to peanut oil. Several researchers [3-7] experimented the use of vegetable oils as fuel on conventional engines (CE) and reported that the performance was poor, citing the above mentioned problems of high viscosity, low volatility and their polyunsaturated character. Bio-diesels derived from vegetable oils present a very promising alternative to diesel fuel since biodiesels have numerous advantages compared to fossil fuels as they are renewable, biodegradable, provide energy security and foreign exchange savings besides addressing environmental concerns and socio-economic issues. Experiments were carried out [8-12] with bio-diesel on CE and reported performance was compatible with pure diesel operation on CE. On the other hand alcohols are renewable and volatile fuels. There are many methods of inducting alcohols in diesel engines, out of which carburetion technique is simple one. Alcohol was inducted through a variable jet carburetor, installed in inlet manifold and diesel was injected in conventional manner. Investigations were carried out [13- 16] with carbureted alcohol and diesel on CE and reported that exhaust emissions of smoke and NOx decreased n comparison with pure diesel operation on CE. However, alcohols have low Cetane number. Hence engine modification was necessary if alcohol was used as fuel in diesel engine. The drawbacks of the crude vegetable oil, biodiesel and alcohol call for hot combustion chamber provided by LHR diesel engine. The major concept of LHR engine is to reduce heat loss to the coolant, by providing thermal insulation in the path of heat flow to the coolant. LHR engines were classified depending on degree of insulation, such as low grade, medium grade and high grade engines. In low grade LHR engines, ceramic coatings were provided on piston, liner and cylinder head while in medium grade LHR engines, air gap was created in the piston and other components with low- thermal conductivity materials like superni, cast iron and mild steel etc. High grade LHR engines were the combination of low grade and medium grade. Investigations were carried out by various researchers [17- 19] on low grade LHR ceramic coated diesel engines with pure diesel operation and reported that pollution levels of smoke decreased by 15% with ceramic coated engine. Experiments were carried out [20-23] with biodiesel in low grade LHR diesel engine and reported that there was reduction of smoke levels and increase of NOx levels.