Avinash Kumar Agarwal

EFFECT OF BIODIESEL UTILIZATION OF WEAR OF VITAL PARTS IN COMPRESSION IGNITION ENGINE

The combustion related properties of vegetable oils are somewhat similar to diesel oil. Neat vegetable oils or their blends with diesel, however, pose various long-term problems in compression ignition engines, e.g., poor atomization characteristics, ring-sticking, injector coking, injector deposits, injector pump failure, and lube oil dilution by crank-case polymerization. These undesirable features of vegetable oils are because of their inherent properties like high viscosity, low volatility, and polyunsaturated character. Linseed oil methyl ester (LOME) was prepared using methanol for long-term engine operations. The physical and combustion-related properties of the fuels thus developed were found to be closer to that of the diesel oil. A blend of 20 percent was selected as optimum biodiesel blend. Two similar new engines were completely disassembled and subjected to dimensioning of various vital moving parts and then subjected to long-term endurance tests on 20 percent biodiesel blend and diesel oil, respectively. After completion of the test, both the engines were again disassembled for physical inspection and wear measurement of various vital parts. The physical wear of various vital parts, injector coking, carbon deposits on piston, and ring sticking were found to be substantially lower in case of 20 percent biodiesel-fuelled engine. The lubricating oil samples drawn from both engines were subjected to atomic absorption spectroscopy for measurement of various wear metal traces present. AAS tests confirmed substantially lower wear and thus improved life for biodiesel operated engines.

WEAR ASSESSMENT IN A BIODIESEL FUELED COMPRESSION IGNITION ENGINE

Biodiesel is prepared using linseed oil and methanol by the process of transesterification. Use of linseed oil methyl ester (LOME) in a compression ignition engine was found to develop a highly compatible engine-fuel system with low emission characteristics. Two similar engines were operated using optimum biodiesel blend and mineral diesel oil, respectively. These were subjected to long-term endurance tests. Lubricating oil samples drawn from both engines after a fixed interval were subjected to elemental analysis. Quantification of various metal debris concentrations was done by atomic absorption spectroscopy (AAS). Wear metals were found to be about 30% lower for a biodiesel-operated engine system. Lubricating oil samples were also subjected to feirography indicating lower wear debris concentrations for a biodiesel-operated engine. The additional lubricating property of LOME present in the fuel resulted in lower wear and improved life of moving components in a biodiesel-fuelled engine. However, this needed experimental verification and quantification. A series of experiments were thus conducted to compare the lubricity of various concentrations of LOME in biodiesel blends. Long duration tests were conducted using reciprocating motion in an SRV optimol wear tester to evaluate the coefficient of friction, specific wear rates, etc. The extent of damage, coefficient of friction, and specific wear rates decreased with increase in the percentage of LOME in the biodiesel blend. Scanning electron microscopy was conducted on the surfaces exposed to wear. The disk and pin using 20% biodiesel blend as the lubricating oil showed lesser damage compared to the one subjected to diesel oil as the lubricating fluid, confirming additional lubricity of biodiesel.

Experimental investigations of the effect of biodiesel utilization on lubricating oil tribology in diesel engines

Biodiesel is an alternative fuel derived from vegetable oils by modifying their molecular structure through a transesterification process. Linseed oil methyl ester (LOME) was prepared using methanol in the presence of potassium hydroxide as a catalyst. The use of LOME in compression ignition engines was found to develop a very compatible engine-fuel system with lower emission characteristics. Two identical engines were subjected to long-term endurance tests, fuelled by an optimum biodiesel blend (20 per cent LOME) and diesel oil, respectively. Various tribological studies on lubricating oil samples drawn at regular intervals from both engines were conducted in order to correlate the comparative performance of the two fuels and the effect of fuel chemistry on lubricating oil performance and life. A number of tests were conducted in order to evaluate the comparative performances of the two fuels such as density measurement, viscosity measurements, Flashpoint determination, moisture content determination, pentane and benzene insolubles, thin layer chromatography, differential scanning calorimetry, etc. All these tests were used for an indirect interpretation of the comparative performance of these fuels. The performance of biodiesel fuel is found to be superior to that of diesel oil and the lubricating oil life is found to be longer while operating the engine on biodiesel

Development of surface functionalized activated carbon fiber for control of NO and particulate matter

This study investigates the development and potential application of activated carbon fibers (ACF) functionalized with ammonia for control of NO and particulate matter (PM) in diesel engine exhaust. A tubular reactor packed with ACF was used to experimentally study the oxidation of NO at room temperature. Tests were conducted at ACF functionalized with three aqueous ammonia concentrations (3, 5, 10 M), three basic reagents (ammonia, pyridine, amine) and three NO concentrations (100, 300, 500 ppm). After offline investigation, the ACF-packed tubular reactor was installed downstream of the engines exhaust to ascertain the PM capturing efficiency of ACF. The experimental conditions for PM removal included three weights of ACF (2, 3.5, 4.5 g), three engine loads (0, 25, 50 Nm) and three temperatures (150, 300, 450 degrees C). The maximum 70% conversion for NO was obtained at NO concentration of 300 ppm for ACF functionalized with 5M ammonia, whereas maximum 90% reduction in PM was observed at engine load of 25 Nm and 450 degrees C. The study shows significant potential for the ACF based filters in capturing both homogeneous and heterogeneous pollutants emitted from automobiles. Our previously developed transport model incorporating the mechanism for the oxidation of NO was also used to explain the experimental data.

Experimental Investigation of the Effect of Biodiesel Utilization on Lubricating Oil Degradation and Wear of a Transportation CIDI Engine

Increased environmental awareness and depletion of fossil petroleum resources are driving industry to develop alternative fuels that are environmentally more acceptable. Biodiesel is an alternative fuel derived from vegetable oils by modifying its molecular structure. In the present experimental research work, methyl ester of rice-bran oil (ROME) is derived through transesterification of rice-bran oil using methanol in presence of sodium hydroxide (NaOH) catalyst. On the basis of previous research for performance, emission and combustion characteristics, a 20% blend of ROME (B20) was selected as optimum biodiesel blend. In the present research, the experimental investigation was aimed to investigate the effect of biodiesel on wear of in-cylinder components. Endurance tests were conducted on a medium duty direct injection transportation diesel engine with 20% blend of the ROME with mineral diesel. Tests were conducted under predetermined loading cycles in two phases: engine operating on mineral diesel and engine fuelled with 20% biodiesel blend. After completion of the tests, engines were dismantled for observing the physical condition of the various parts, e.g. piston rings, bearings, cylinder liner, cylinder head etc. Physical measurements of various vital parts were also carried out to assess the wear of the parts of engine. The physical wear of various parts except big end bearings were found to be lower in case of 20% biodiesel fuelled engine. Wear metals in the lubricating oil samples drawn from the engines at regular intervals were investigated. Relatively lower wear concentration of all wear metals except lead were found in the lubricating oil of B20 fuelled engine. Two quantify the wear of cylinder liners, surface parameters at different locations in the liner (TDC, BDC and mid-stroke) were measured and investigated. A qualitative analysis was also carried out by taking surface profiles and conducting scanning electron microscopy at same locations.Copyright

Experimental investigation of the effect of the intake air temperature and mixture quality on the combustion of a methanol- and gasoline-fuelled homogeneous charge compression ignition engine

Abstract Environmental concerns have increased significantly all over the world in the past decade. To fulfil the simultaneous emission requirements for near-zero pollutant and low carbon dioxide (CO2) levels, which are the challenges for the future powertrains, many studies are currently being carried out on new engine combustion processes, such as controlled autoignition for gasoline engines and homogeneous charge compression ignition (HCCI) for diesel engines. These combustion processes have the potential for ultra-low nitrogen oxide (NO x ) and particulate matter emissions in comparison with conventional gasoline or diesel engines. In this paper, the combustion characteristics of a HCCI engine fuelled with methanol and gasoline were investigated on a modified two-cylinder four-stroke engine. The port fuel injection technique is used to prepare a homogeneous charge of fuel and air. The experiment is conducted with various intake air temperatures ranging from 120°C to 160°C at different air-to-fuel ratios, for which stable HCCI combustion is achieved. The experimental results indicate that the inlet air temperature and air-to-fuel ratio have a significant effect on the maximum in-cylinder pressure and its position relative to top dead centre, the shape of the pressure rise curve, and the heat release rates. The results confirm that the inlet air temperature is a very sensitive parameter in controlling combustion timing and thus the effectiveness of the HCCI combustion process.

Performance Evaluation of a Biodiesel (Rice Bran Oil Methyl Ester) Fuelled Transport Diesel Engine

This experimental study was undertaken to investigate the use of vegetable oil derivatives to substitute mineral diesel fuel. Straight vegetable oils pose some problems like injector coking, carbon deposits etc., when used as a fuel in an engine. These problems are due to high viscosity, low volatility and polyunsaturated character of vegetable oils. Transesterified vegetable oil derivative called “biodiesel” appear to be most convenient way of utilizing vegetable oil as a substitute fuel in diesel engines. In present investigation, rice bran oil (non-edible) was transesterified to methyl ester and reaction conditions for transeterifcation process for rice bran oil were optimized. Various properties like viscosity, density, flash point of the biodiesel thus prepared are comparable to diesel and found to be in acceptable range as per ASTM norms (ASTM D6751). Experimental investigations were carried out on a four stroke, four cylinders, transportation DI diesel engine. Various blends of biodiesel (rice bran methyl ester) and diesel ranging from 5% to 50% ester in the blend were used for performance and emission test in the transport diesel engine and the results are compared with the baseline data obtained using mineral diesel. Detailed engine tests show that biodiesel can be used as partial substitute fuel in existing diesel engines without substantial hardware modification and it significantly lower the emissions of harmful species from diesel engines without jeopardizing the engine performance.

Experimental investigations of comparative performance, emission and combustion characteristics of a cottonseed biodiesel-fueled four-stroke locomotive diesel engine

A large-bore, four-stroke, medium-speed, compression-ignition railway traction locomotive engine was fueled with cottonseed methyl ester (Biodiesel). The cottonseed methyl ester was stored for 6 months under ordinary storage conditions, and various fuel properties of this seasoned cottonseed methyl ester were evaluated. Various blends of cottonseed methyl ester (B10, B20, B50 and cottonseed methyl ester) were evaluated for engine performance, emissions and combustion characteristics of the locomotive engine compared to baseline diesel. Correlation of the fuel-injection performance parameters with the physical properties of biodiesel has been carried out. The engine was able to operate on cottonseed methyl ester without noticeable power loss. With cottonseed methyl ester, the thermal efficiency decreased marginally by 0.7% and the brake-specific energy consumption increased by 0.1 MJ/kWh at the rated power. Due to the lower calorific value of biodiesel, brake specific fuel consumption (BSFC) increased by 13.4% at eighth engine notch, nitrogen oxide emissions increased by 8% and particulate matter emissions decreased by 32% vis-a-vis mineral diesel. Nitrogen oxide emissions were found to be a function of injection timings, global oxygen/carbon ratios, time of the maximum mean in-cylinder temperatures and apparent heat release. Particulate matter emissions were found to depend on the air–fuel mixture’s oxygen/carbon ratio, fuel bound oxygen and fuel-injection pressure. The experiments were carried out to evaluate the in-cylinder pressure, heat-release rate, cumulative heat release, fuel-injection pressure, needle lift and fuel-injection velocities. Increased fuel-injection pressures (1000 bar compared to 900 bar for mineral diesel), advanced fuel-injection timings, shorter combustion duration, advanced in-cylinder pressures and higher heat-release rates were observed for biodiesel and blends. The findings of the present study have provided further insights into the combustion of biodiesel in locomotive engines.

Experimental Investigation of Cycle-by-Cycle Variations in CAI/HCCI Combustion of Gasoline and Methanol Fuelled Engine

The development of vehicles continues to be determined by increasingly stringent emissions standards including CO2 emissions and fuel consumption. To fulfill the simultaneous emission requirements for near zero pollutant and low CO2 levels, which are the challenges of future powertrains, many research studies are currently being carried out world over on new engine combustion process, such as Controlled Auto Ignition (CAI) for gasoline engines and Homogeneous Charge Compression Ignition (HCCI) for diesel engines. In HCCI combustion engine, ignition timing and combustion rates are dominated by physical and chemical properties of fuel/air/residual gas mixtures, boundary conditions including ambient temperature, pressure, and humidity and engine operating conditions such as load, speed etc. Because of large variability of these factors, wide cycle-to-cycle variations are observed in HCCI combustion engines, similarly small variations in ignition timing and combustion rates result in wide variation in engine performance and emissions. Also, cycle-to-cycle combustion variations result in objectionable engine noise and vibrations. As a result of wide cycle-to-cycle variations, HCCI combustion can be achieved in an engine for narrow range of lean and rich operating limits. This motivates the researchers to systematically investigate mechanism and control of cycle-to-cycle variations on HCCI engines. In this paper, the combustion stabilities and cycle-tocycle variations of a HCCI combustion engine fuelled with gasoline and methanol were investigated on a modified two-cylinder, four-stroke engine. In this investigation, port fuel injection technique is used for preparing homogeneous charge. The experiment is conducted with variable intake air temperature at different air-fuel ratios at constant engine speed. Incylinder pressure of 100 combustion cycles for each test condition was recorded. Consequently, cycle-to-cycle variations of the main combustion parameters and performance parameters were analyzed and evaluated. To evaluate the cycle-to-cycle variations of HCCI combustion parameters at various test conditions, coefficient of variation (COV) of each parameter was used. The results show that critical parameters, which can be used to define HCCI operating range, are maximum rate of pressure rise, and COV of indicated mean effective pressure (IMEP).

Performance, Emission and Combustion Characteristics of Jatropha Oil Blends in a Direct Injection CI Engine

Vegetable oils have energy content suitable to be used as compression ignition (CI) engine fuel. However, several operational and durability problems of using straight vegetable oils in CI engines are reported in the literature, which are primarily caused by their higher viscosity and low volatility compared to mineral diesel. The viscosity can be brought in acceptable range by (i) chemical process of transesterification, (ii) blending of oil with mineral diesel or (iii) by heating the vegetable oil using exhaust gas waste heat. Reduction of viscosity by blending or exhaust gas heating saves the chemical processing cost of transesterification. Present experimental investigations were carried out for evaluating combustion, performance and emission behavior of Jatropha oil blends in unheated conditions in a direct injection CI engine at different load and constant engine speed (1500 rpm). Analysis of in-cylinder pressure rise, instantaneous heat release and cumulative heat release was carried out. All test blends exhibited similar combustion stages as mineral diesel; however, Jatropha oil blends showed earlier start of combustion but lower heat release rate during premixed combustion phase for all engine loads. The crank angle position of peak cylinder pressure for vegetable oil blends shifts towards top dead center compared to baseline diesel. Combustion duration was found to be comparable with diesel up to 20% concentration of Jatropha oil in the fuel. HC, CO and NO emissions were found to slightly increase with increase in Jatropha oil content in the fuel blends.