M.V.S. Murali Krishna

Performance Evaluation of a Low-Grade Low-Heat-Rejection DieselEngine with Crude Pongamia oil

Investigations are carried out to evaluate the performance of a low heat rejection (LHR) diesel engine with ceramic coated cylinder head [ceramic coating of thickness 500 microns is done on inside portion of cylinder head] with different operating conditions [normal temperature and pre-heated temperature] of crude Pongamia oil (CPO) with varied injection pressure and injection timing. Performance parameters and pollution levels are determined at various magnitudes of brake mean effective pressure. Combustion characteristics at peak load operation of the engine are measured with special pressure-crank angle software package. Conventional engine (CE) showed deteriorated performance, while LHR engine showed improved performance with CPO operation at recommended injection timing and pressure and the performance of both version of the engine is improved with advanced injection timing and at higher injection pressure when compared with CE with pure diesel operation. The optimum injection timing is 31°bTDC for conventional engine while it is 29°bTDC with LHR engine with vegetable oil operation. Peak brake thermal efficiency increased by 5%, smoke levels decreased by 2% and NOx levels increased by 40% with CPO operation on LHR engine at its optimum injection timing, when compared with pure diesel operation on CE at manufacturer’s recommended injection timing.

Performance of copper coated two stroke spark ignition engine with methanol-blended gasoline with catalytic converter

This paper reports performance evaluation of two-stroke, single cylinder spark ignition (SI) engine with methanol blended gasoline (80% gasoline, 20% methanol by volume) having copper coated engine (CCE) [copper (thickness, 300 μm) coated on piston crown, and inner side of cylinder head] provided with catalytic converter with sponge iron as catalyst and compared with conventional SI engine with gasoline operation. Brake thermal efficiency increased with methanol blended gasoline with both versions of the engine. CCE showed improved performance when compared to conventional engine (CE) with both test fuels. Catalytic converter with air injection significantly reduced pollutants with both test fuels on both configurations of the engine.

An Assessment of Antibacterial Activity of Four Endodontic Sealers on Enterococcus faecalis by a Direct Contact Test: An In Vitro Study

Aim. To evaluate the antibacterial activity of four endodontic sealers on Enterococcus faecalis by a direct contact test. Material and Methods. Enterococcus faecalis was used as a test organism. Direct contact test which is based on measuring the effect of close contact between test bacteria and tested material on the kinetics of bacterial growth was performed to overcome the disadvantages of agar diffusion test. The sealers tested were zinc oxide eugenol-based sealer, glass-ionomer-based sealer, polydimethyl-siloxane-based sealer, and urethane dimethacrylate resin-based sealer. Data was collected by recording the optical density with the help of a spectrophotometer. Results. The sealers exhibited different inhibitory effects. The results obtained were subjected to statistical analysis by Kruskal Wallis analysis of variance and Dunns multiple comparison test. Group comparison showed very highly significant difference between the groups. Conclusion. Zinc oxide eugenol-based sealer was the most effective and urethane dimethacrylate resin-based sealer was the least effective against Enterococcus faecalis, whereas glass-ionomer-based and polydimethyl-siloxane-based sealers were effective only for a short period. Inhibition of the bacterial growth is related to the direct contact of the microorganism with the sealer.

Experimental Investigations on DI Diesel Engine with Different Combustion Chambers Insulation

Aim: The four-stroke single cylinder diesel engine’s performance with various low heat rejection (LHR) combustion chambers was determined Critical comparison was made for various configurations of the combustion chambers with neat diesel operation. Design Parameters: Direct injection diesel engine with various configurations of the combustion chambers–Combustion chamber with air gap insulation and ceramic coating (LHR–3); air gap insulation (LHR–2); and ceramic coated combustion chamber (LHR–1) Injection pressure and timing. Original Research Article Krishna et al.; BJAST, 6(3): 239-260, 2015; Article no.BJAST.2015.084 240 Materials and Methods: Exhaust emissions and performance parameters and were evaluated at different values of brake mean effective pressure (BMEP) of the engine. Combustion parameters were evaluated at its peak load operation. Particulate emissions were determined by smoke opacity meter (AVL 437), while nitrogen oxide levels were noted by NOx Analyzer (Netel Chromatograph NOx Analyzer (VM 4000). Combustion characteristics of the engine were determined at peak load operation of the engine using TDC (top dead centre) encoder, miniature Piezo electric pressure transducer, and special p (pressure)– (crank angle) software package. Brief Results: Deteriorated performance was shown by the engine with air gap insulated and ceramic coated (LHR–3) combustion chamber, when compared with engine with other configurations of the combustion chamber at recommended injection timing of 27° bTDC.(before top dead centre) Conclusions: Engine with LHR–1, LHR–2 and LHR–3 combustion chambers with mineral diesel operation showed deteriorated performance at 27° bTDC and improved at optimum injection timings and with increased injection pressure.

Potential of a Medium Grade Low Heat Rejection Diesel Engine With Crude Tobacco Seed Oil

Investigations were carried out to evaluate the performance of a 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 different operating conditions of crude tobacco seed oil (CTSO) with varied injection timing and injection pressure.

Performance Evaluation of a Low Heat Rejection Diesel Engine with Jatropha Oil

Investigations were carried out to evaluate the performance of a 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 different operating conditions of crude jatropha oil (CJO) with varied injection timing and injector opening pressure . Performance parameters [brake thermal efficiency, exhaust gas temperature, coolant load and volumetric efficienc and exhaust emissions [smoke and oxides of nitroge were determined at various values of brake mean effective pressure (BMEP). Combustion characteristics [ peak pressure, time of occurrence of peak pressure and maximum rate of pressure ris of the engine were at peak load operation of the engine. Conventional engine (CE) showed deteriorated performance, while LHR engine showed improved performance with vegetable operation at recommended injection timing and pressure. The performance of both versions of the engine improved with advanced injection timing and higher injector opening pressure when compared with CE with pure diesel operation. Relatively, peak brake thermal efficiency increased by 14%, smoke levels decreased by 27% and NOx levels increased by 49% with vegetable oil operation on LHR engine at its optimum injection timing, when compared with pure diesel operation on CE at manufacturers recommended injection timing.

Studies on Exhaust Emissions from Copper-Coated Gasohol Run Spark Ignition Engine with Catalytic Converter

The major pollutants emitted from spark ignition engine are carbon monooxide (CO) and unburnt hydrocarbons (UHC). These are hazardous and cause health problems to human beings, and hence control of these pollutants calls for immediate attention. Copper of thickness 300 microns is coated over piston crown and inside portion of the cylinder head of the spark ignition engine. Investigations have been carried out for reducing pollutants from a variable compression ratio, copper-coated spark ignition engine fitted with catalytic converter containing sponge iron catalyst run with gasohol (blend of 20% ethanol and 80% gasoline by volume). The influence of parameters such as void ratio, airflow rate, temperature of injected air, speed, compression ratio, and load of the engine on these emissions are studied. A microprocessor-based analyzer is used for the measurement of CO/UHC in the exhaust of the engine. The speed, load, compression ratio and the injection of air into the catalytic converter are found to show strong influence on reduction of the pollutants in the exhaust. Copper-coated spark ignition engine with gasohol operation reduced the exhaust emissions considerably when compared to conventional engine with pure gasoline operation.

Comparative Studies on Performance and Emissions of Two Stroke and Four Stroke Copper Coated Spark Ignition Engines With Methanol Blended Gasoline

Investigations were carried out to evaluate the performance of two stroke and four stroke of single cylinder, spark ignition (SI) engines having copper coated engine [CCE, copper-(thickness, 300 μ)] coated on piston crown and inner side of cylinder head] provided with catalytic converter with sponge iron as catalyst with methanol blended gasoline (80% gasoline and 20% methanol by volume) and compared with conventional engine (CE) with pure gasoline operation.Performance parameters — brake thermal efficiency (BTE), exhaust gas temperature (EGT), volumetric efficiency and exhaust emissions of carbon monoxide (CO) and un-burnt hydrocarbon (UBHC) were determined with different values of brake mean effective pressure (BMEP) of the engine and compared with one over the other of two stroke and four stroke SI engine with different versions of the engine.Formaldehyde and acetaldehyde emissions were measured by 2, 4 dinitrophenyl hydrazine (2,4 DNPH) method at peak load operation of CE and CCE of two-stroke and four-stroke SI engine. The engine was provided with catalytic converter with sponge iron as catalyst. There was provision for injection of air into the catalytic converter.Brake thermal efficiency increased with methanol blended gasoline with both versions of the engine. CCE showed improvement in the performance when compared with CE with both test fuels. Four-stroke engine decreased exhaust emissions effectively in comparison with two-stroke engine with both versions of the engine. Catalytic converter with air injection significantly reduced exhaust emissions with different test fuels on both configurations of the engine.Copyright

Control of Nitrogen Oxides in Diesel Engine Exhaust by Catalytic Reduction

The nitrogen oxides (NOx) are prominent and harmful pollutants in the exhaust of diesel engines. The reduction of NOx to harmless products using catalysts is proved to be a remedy. The present study attempts to reduce NOx emissions in the exhaust of low heat rejection (LHR) diesel engine by catalytic reduction, using lanthanum ion exchanged zeolite (catalyst-A) and urea infused lanthanum ion exchanged zeolite (catalyst-B) under varied conditions . The effect of temperature of catalyst, space velocity, and void ratio on the reduction of NOx in the exhaust of the engines are also studied and compared with the conventional engine (CE) under identical conditions. The study showed a considerable reduction by 40-50% in NOx emissions.

Investigations on Low Heat Rejection Diesel Engine With Crude Jatropha Oil as an Alternate Fuel

Jatropha oil, a non-edible vegetable oil shows a greater potential for replacing conventional diesel fuel quite effectively, as its properties are compatible to that of diesel fuel. But low volatility and high viscosity of jatropha oil call for hot combustion chamber, which is provided by a low heat rejection diesel engine with threaded air gap piston and liner with superni-90 inserts. The performance of the engine with jatropha oil is obtained with different versions of the engine such as conventional engine and insulated engine at normal and preheat condition of the oil, with varying injection pressure and timing and compared to the engine with pure diesel operation at recommended injection pressure and timing. Increase of thermal efficiency of 18% and reduction of NOx levels by 5% are observed at optimized injection timing and at higher injection pressure with insulated engine at preheat condition of jatropha oil in comparison with pure diesel operation on conventional engine.Copyright