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Krishna M.V.S.M.,Chaitanya Bharathi Institute of Technology | Rao N.D.P.,Hindustan Aeronautics Ltd | Murthy P.V.K.,Jaya Prakash Narayan Educational Society Group of Institutions
Archive of Mechanical Engineering | Year: 2014

It has been found that the vegetable oils are promising substitute, because of their properties are similar to those of diesel fuel and they are renewable and can be easily produced. However, drawbacks associated with crude vegetable oils are high viscosity, low volatility call for low heat rejection combustion chamber, with its significance characteristics of higher operating temperature, maximum heat release, and ability to handle lower calorific value (CV) fuel etc. Experiments were carried out to evaluate the performance of an engine consisting of different low heat rejection (LHR) combustion chambers such as ceramic coated cylinder head-LHR-1, air gap insulated piston with superni (an alloy of nickel) crown and air gap insulated liner with superni insert - LHR-2; and ceramic coated cylinder head, air gap insulated piston and air gap insulated liner - LHR-3 with normal temperature condition of crude rice bran oil (CRBO) with varied injector opening pressure. Performance parameters (brake thermal efficiency, brake specific energy consumption, exhaust gas temperature, coolant load, and volumetric efficiency) and exhaust emissions [smoke levels and oxides of nitrogen [NOx]] were determined at various values of brake mean effective pressure of the engine. Combustion characteristics [peak pressure, time of occurrence of peak pressure, maximum rate of pressure rise] were determined at full load operation of the engine. Conventional engine (CE) showed compatible performance and LHR combustion chambers showed improved performance at recommended injection timing of 27°bTDC and recommend injector opening pressure of 190 bar with CRBO operation, when compared with CE with pure diesel operation. Peak brake thermal efficiencyincreased relatively by 7%, brake specific energy consumption at full load operation decreased relatively by 3.5%, smoke levels at full load decreased relatively by 11% and NOx levels increased relatively by 58% with LHR-3 combustion chamber with CRBO at an injector opening pressure of 190 bar when compared with pure diesel operation on CE. Source


Nagini Y.,Chaitanya Bharathi Institute of Technology | Naga Sarada S.,Andhra University | Murali Krishna M.V.S.,Chaitanya Bharathi Institute of Technology | Murthy P.V.K.,Jaya Prakash Narayan Educational Society Group of Institutions
International Energy Journal | Year: 2012

Experiments were carried out to study the exhaust emissions of variable speed, variable compression ratio, four- stroke, single cylinder, spark ignition (SI) engine having copper coated engine [CCE, copper-(thickness, 300 μ) coated on piston crown and inner side of cylinder head] provided with catalytic converter with different catalysts of sponge iron and manganese ore with different test fuels of pure gasoline and gasohol (80% gasoline and 20% ethanol by volume) and compared with conventional engine (CE) with pure gasoline operation. Exhaust emissions of carbon monoxide (CO) and un-burnt hydro carbon (UBHC) were varied with different values of brake mean effective pressure (BMEP), speed, compression ratio with different operating conditions of catalytic converter with different catalyst. Aldehyde emissions were measured at peak load operation. CO and UBHC) were measured with Netel Chromatograph CO/UBHC analyzer. The engine was provided with catalytic converter with sponge iron and manganese ore as catalysts. There was provision for injection of air into the catalytic converter. The performance of the catalyst was compared with one over the other. Gasohol operation on CCE decreased exhaust emissions effectively in comparison with pure gasoline operation on CE. Catalytic converter with air injection significantly reduced pollutants with different test fuels on both configurations of the engine. Source


Krishna M.V.S.M.,Chaitanya Bharathi Institute of Technology | Prakash T.O.,Mancherial | Ushasri P.,Osmania University | Janardhan N.,Chaitanya Bharathi Institute of Technology | And 2 more authors.
Renewable and Sustainable Energy Reviews | Year: 2016

Alcohols and vegetable oils are important substitutes for diesel fuel, as they are renewable in nature in the context of depletion of fossil fuels. Compression ignition (CI) engines, due to their excellent fuel efficiency and durability, have become popular power plants for automotive applications. Vegetable oils have energy content suitable to be used as compression ignition engine fuel. Problems associated with crude vegetable oil (high viscosity and low volatility) and alcohol (low cetane number and energy content) call for engine with low heat rejection (LHR) combustion chamber with its significance characteristics of higher operating temperature, maximum heat release, higher brake thermal efficiency and ability to handle the lower calorific value fuel. Investigations were carried out to evaluate the performance of the engine with LHR combustion chamber consisting of ceramic coated cylinder head fueled with crude jatropha oil with carbureted alcohol with varied injection timing and pressure. Alcohol (ethanol/methanol) was inducted through a variable jet carburetor, installed at the inlet manifold of the engine at different percentages of jatropha oil [at full load operation by mass basis at manufacturer's recommended injection timing of 27° bTDC (before top dead center) with conventional engine (CE)] during suction stroke and crude jatropha oil was injected at near end of compression stroke. Comparative studies were made with pure vegetable oil operation with similar operating conditions and also with alcohols. Engine with LHR combustion chamber with maximum induction of alcohol along with injected crude jatropha oil showed improved performance over CE at 27° bTDC and 31° bTDC. However, it increased nitrogen oxide (NOx) levels. Ethanol operation showed improved performance with CE, while methanol operation showed improved performance with engine with LHR combustion chamber. Alcohol operation increased aldehydes drastically with both versions of the combustion chamber with varied engine parameters, when compared with pure vegetable oil operation. © 2015 Elsevier Ltd. All rights reserved. Source


Murali Krishna M.V.S.,Chaitanya Bharathi Institute of Technology | Pavan Kumar P.,Jaya Prakash Narayan Educational Society Group of Institutions | Murthy P.V.K.,Chaitanya Bharathi Institute of Technology | Baswaraju D.,Chaitanya Bharathi Institute of Technology
ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) | Year: 2013

Investigations were carried out to evaluate the performance of a medium 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 and air gap insulated liner with superni insert with different operating conditions of crude tobacco seed oil with varied injection timing and injection pressure. Performance parameters of brake thermal efficiency (BTE), exhaust gas temperature (EGT), volumetric efficiency (VE), coolant load (CL) and sound intensity were determined at various values of brake mean effective pressure (BMEP) of the engine. Exhaust emissions of smoke and oxides of nitrogen (NOx) were noted at different values of BMEP of the engine. Combustion characteristics of peak pressure (PP), time of occurrence of peak pressure(TOPP), maximum rate of pressure rise (MRPR) and time of occurrence of maximum rate of pressure (TOMRPR) were measured with TDC (top dead centre) encoder, pressure transducer, console and special pressure-crank angle software-package at the peak load operation of the engine. Conventional engine (CE) showed deteriorated performance, while LHR engine showed improved performance with crude tobacco seed oil (CTSO) operation when compared with pure diesel operation at recommended injection timing and pressure. The optimum injection timing was found to be 32°bTDC (before top dead centre) with CE while it was 30°bTDC with LHR engine with vegetable oil operation. The performance of both version of the engine improved with advanced injection timing and higher injection pressure with test fuels. Peak brake thermal efficiency increased by 4%, volumetric efficiency decreased by 8%, smoke levels decreased by 4% and NOx levels increased by 37% with vegetable oil operation on LHR engine at its optimum injection timing, when compared with pure diesel operation on CE at manufacturer's recommended injection timing of 27°bTDC. Copyright © 2013 by ASME. Source


Krishna M.V.S.M.,Chaitanya Bharathi Institute of Technology | Rao V.V.R.S.,Chaitanya Bharathi Institute of Technology | Reddy T.K.K.,JNTUH College of Engineering | Murthy P.V.K.,Jaya Prakash Narayan Educational Society Group of Institutions
Renewable and Sustainable Energy Reviews | Year: 2014

Search for renewable fuels such as vegetable oils and alcohols (ethanol and methanol) has become pertinent in the context of fossil fuel crisis and vehicle population explosion. The drawbacks associated with vegetable oils (high viscosity and low volatility) and alcohols (low cetane number) for use in diesel engines call for a hot combustion chamber, with its significant characteristics of higher operating temperature, maximum heat release, higher brake thermal efficiency and ability to handle the lower calorific value fuel. Investigations were carried out to evaluate the performance of a direct injection compression ignition engine with high grade low heat rejection (LHR) combustion chamber 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 fueled with crude jatropha oil and carbureted alcohol (ethanol/methanol) with varied injection timings and injector opening pressures. Carbureted alcohol was inducted into the engine through a variable jet carburetor, installed at the inlet manifold of the engine at different percentages of crude vegetable oil at full load operation on mass basis. Comparative studies were made with engine with LHR combustion chamber with data of conventional engine with test fuels of diesel, crude vegetable oil and carbureted alcohol at recommended injection timing and optimized injection timing. Comparative studies were also made with methanol operation with data of ethanol operation on both versions of the combustion chamber with different operating conditions. Performance parameters, exhaust emissions and combustion characteristics were determined at full load operation of the engine with varied injection timings and injector opening pressures. Aldehydes were measured by the dinitrophenyl hydrazine (DNPH) method. Combustion diagnosis was carried out with a miniature piezoelectric pressure transducer, top dead center (TDC) encoder and special pressure-crank angle software package. The optimum injection timing was observed to be 32° bTDC with conventional engine while it was 29° bTDC for insulated engine with vegetable oil operation. The maximum induction of alcohol (methanol/ethanol) in conventional engine was found to be 35%, while it was 60% for the engine with LHR combustion chamber at recommended injection timing (27° bTDC). However, the maximum induction of alcohol was observed to be 55% with engine with LHR combustion chamber at its optimum injection timing. With maximum induction of methanol, at an injector opening pressure of 190 bar, engine with LHR combustion chamber at its optimum injection timing increased peak brake thermal efficiency by 3%; at full load operation brake specific energy consumption comparable, decreased exhaust gas temperature by 3%, decreased coolant load by 6%, volumetric efficiency comparable, increased formaldehyde levels by 30%, decreased acetaldehyde levels by 35%, decreased particulate emissions by 20%, decreased nitrogen oxide levels by 14%, increased peak pressures by 3% and maximum rate of pressure rose by 3%, when compared with ethanol operation on engine with LHR combustion chamber at its optimum injection timing. © 2014 Elsevier Ltd. Source

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