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    Experimental investigations on a jatropha oil methanol dual fuel engine
    (01-01-2001)
    Kumar, M. Senthil
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    Nagalingam, B.
    Use of vegetable oils in diesel engines results in increased smoke and reduced brake thermal efficiency. Dual fuel engines can use a wide range of fuels and yet operate with low smoke emissions and high thermal efficiency. In this work, a single cylinder diesel engine was converted to use vegetable oil (Jatropha oil) as the pilot fuel and methanol as the inducted primary fuel. Tests were conducted at 1500 rev/min and full load. Different quantities of methanol and Jatropha oil were used. Results of experiments with diesel as the pilot fuel and methanol as the primary fuel were used for comparison. Brake thermal efficiency increased in the dual fuel mode when both Jatropha oil and diesel were used as pilot fuels. The maximum brake thermal efficiency was 30.6% with Jatropha oil and 32.8% with diesel. Smoke was drastically reduced from 4.4 BSU with pure Jatropha oil operation to 1.6 BSU in the dual fuel mode. Hydrocarbon and carbon monoxide emissions were higher in the dual fuel mode with both fuels. Heat release pattern in the case of neat Jatropha oil operation showed a smaller premixed combustion phase and a larger diffusion combustion phase as compared to diesel operation. These phases were not distinguishable in the dual fuel mode. Copyright © 2001 Society of Automotive Engineers, Inc.
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    Use of hydrogen to enhance the performance of a vegetable oil fuelled compression ignition engine
    (01-01-2003)
    Senthil Kumar, M.
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    Nagalingam, B.
    Use of vegetable oils in unmodified diesel engines leads to reduced thermal efficiency and increased smoke levels. In this work, experiments were conducted to evaluate the performance while using small quantities of hydrogen in a compression ignition engine primarily fuelled with a vegetable oil, namely Jatropha oil. A single cylinder water-cooled direct-injection diesel engine designed to develop a power output of 3.7 kW at 1500 rev/min was tested at its rated speed under variable load conditions, with different quantities of hydrogen being inducted. The Jatropha oil was injected into the engine in the conventional way. Results indicated an increase in the brake thermal efficiency from 27.3% to a maximum of 29.3% at 7% of hydrogen mass share at maximum power output. Smoke was reduced from 4.4 to 3.7 BSU at the best efficiency point. There was also a reduction in HC and CO emissions from 130 to 100 ppm and 0.26-0.17% by volume respectively at maximum power output. With hydrogen induction, due to high combustion rates, NO level was increased from 735 to 875 ppm at full output. Ignition delay, peak pressure and maximum rate of pressure rise were also increased in the dual fuel mode of operation. Combustion duration was reduced due to higher flame speed of hydrogen. Higher premixed combustion rate was observed with hydrogen induction. Comparison was made with diesel being used as the pilot fuel instead of vegetable oil. In the case of diesel the brake thermal efficiency was always higher. At the optimum hydrogen share of 5% by mass, the brake thermal efficiency went up from 30.3-32%. Hydrocarbon, carbon monoxide, smoke emission and ignition delay were also lower with diesel as compared to vegetable oil. Smoke level decreased from 3.9 to 2.7 BSU with diesel as pilot at the optimum hydrogen share. Peak pressure, maximum rate of pressure rise, heat release rate and NO levels were higher with diesel than Jatropha oil. On the whole, it is concluded that induction of small quantities of hydrogen can significantly enhance the performance of a vegetable (Jatropha) oil/diesel fuelled diesel engine. © 2003 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.
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    Investigation on the effect of concentration of methane in biogas when used as a fuel for a spark ignition engine
    (01-07-2008)
    Porpatham, E.
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    Nagalingam, B.
    The influence of reduction in the concentration of CO2 in biogas on performance, emissions and combustion in a constant speed spark ignition (SI) engine was studied experimentally. A lime water scrubber was used to lower carbon dioxide (CO2) levels from 41% in biogas to 30% and 20%. The tests covered the range of equivalence ratios from rich to the lean operating limit at a constant speed of 1500 rpm and at compression ratio of 13:1 with a masked valve to enhance swirl. With a reduction in the CO2 level there was a significant improvement in the performance and reduction in emissions of hydrocarbons (HC) particularly with lean mixtures. The lean limit of combustion also gets extended. Heat release rates indicated enhanced combustion rates, which are mainly responsible for the improvement in thermal efficiency. A reduction in the CO2 level by 10% seemed to be sufficient for reducing HC levels and the NO levels were also not significantly raised. The spark timings were to be retarded by about 5° when the CO2 concentration was decreased by 10%. © 2007.
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    Effect of hydrogen addition on the performance of a biogas fuelled spark ignition engine
    (01-08-2007)
    Porpatham, E.
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    Nagalingam, B.
    Hydrogen was added in small amounts (5%, 10% and 15% on the energy basis) to biogas and tested in a spark ignition engine at constant speed at different equivalence ratios to study the effects on performance, emissions and combustion. Hydrogen significantly enhances the combustion rate and extends the lean limit of combustion of biogas. There is an improvement in brake thermal efficiency and brake power. However, beyond 15% hydrogen the need to retard the ignition timing to control knock does not lead to improvements at high equivalence ratios. Significant reductions in hydrocarbon levels were seen. There was no increase in nitric oxide emissions due to the use of retarded ignition timing and the presence of carbon dioxide. Peak pressures and heat release rates are lower with hydrogen addition as the ignition timing is to be retarded to avoid knock. There is a reduction in cycle-by-cycle variations in combustion with lean mixtures. On the whole 10% hydrogen addition was found to be the most suitable. © 2006 International Association for Hydrogen Energy.
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    A comparison of the different methods of using jatropha oil as fuel in a compression ignition engine
    (01-03-2010)
    Kumar, M. Senthil
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    Nagalingam, B.
    Different methods to improve the performance of a jatropha oil based compression ignition engine were tried and compared. A single cylinder water-cooled, direct injection diesel engine was used. Base data were generated with diesel and neat jatropha oil. Subsequently, jatropha oil was converted into its methyl ester by transesterification. Jatropha oil was also blended with methanol and orange oil in different proportions and tested. Further, the engine was modified to work in the dual fuel mode with methanol, orange oil, and hydrogen being used as the inducted fuels and the jatropha oil being used as the pilot fuel. Finally, experiments were conducted using additives containing oxygen, like dimethyl carbonate and diethyl ether. Neat jatropha oil resulted in slightly reduced thermal efficiency and higher emissions. Brake thermal efficiency was 27.3% with neat jatropha oil and 30.3% with diesel. Performance and emissions were considerably improved with the methyl ester of jatropha oil. Dual fuel operation with methanol, orange oil, and hydrogen induction and jatropha oil injection also showed higher brake thermal efficiency. Smoke was significantly reduced from 4.4 BSU with neat jatropha oil to 2.6 BSU with methanol induction. Methanol and orange oil induction reduced the NO emission and increased HC and CO emissions. With hydrogen induction, hydrocarbon and carbon monoxide emissions were significantly reduced. The heat release curve showed higher premixed rate of combustion with all the inducted fuels mainly at high power outputs. Addition of oxygenates like diethyl ether and dimethyl carbonate in different proportions to jatropha oil also improved the performance of the engine. It is concluded that dual fuel operation with jatropha oil as the main injected fuel and methanol, orange oil, and hydrogen as inducted fuels can be a good method to use jatropha oil efficiently in an engine that normally operates at high power outputs. Methyl ester of jatropha oil can lead to good performance at part loads with acceptable levels of performance at high loads also. Orange oil and methanol can be also blended with jatropha oil to improve viscosity of jatropha oil. These produce acceptable levels of performance at all outputs. Blending small quantity of diethyl ether and dimethyl carbonate with jatropha oil will enhance the performance. Diethyl ether seems to be the better of the two. Copyright © 2010 by ASME.
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    Effect of spark timing on the performance of a spark ignition engine running on biogas–hydrogen blends
    (02-11-2017)
    Porpatham, E.
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    Nagalingam, B.
    The influence of hydrogen addition in small quantities to biogas was studied in a spark ignition (SI) stationary engine at different spark timings at fixed equivalence ratio of 0.92. At this condition the engine operated with good thermal efficiency in the neat biogas mode. A single-cylinder diesel engine modified to operate as a SI engine was employed. The speed was 1500 rpm and the throttle opening was fixed at 100% at a compression ratio of 13:1. The maximum power output and thermal efficiency were achieved at a hydrogen energy share of 10%. Beyond this the engine experienced rough operation due to rapid combustion. However, nitric oxide (NO) emissions were high at this condition. At 5% hydrogen addition the hydrocarbon (HC) emission was significantly reduced with good thermal efficiency. NO levels were also low with 5% hydrogen addition as compared to neat biogas operation as retarded ignition timings could be used. The optimum ignition timings were significantly retarded, as the hydrogen quantity was raised. The best operating condition was 5% hydrogen share with a spark timing of 20°bTDC (before Top Dead Centre). It is concluded that addition of small amounts of hydrogen to biogas can significantly improve biogas engine operation.
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    An experimental comparison of methods to use methanol and Jatropha oil in a compression ignition engine
    (01-01-2003)
    Senthil Kumar, M.
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    Nagalingam, B.
    In this work various methods of using vegetable oil (Jatropha oil) and methanol such as blending, transesterification and dual fuel operation were studied experimentally. A single cylinder direct injection diesel engine was used for this work. Tests were done at constant speed of 1500 rev min-1 at varying power outputs. In dual fuel operation the methanol to Jatropha oil ratio was maintained at 3:7 on the volume basis. This is close to the fraction of methanol used to prepare the ester with Jatropha oil. Brake thermal efficiency was better in the dual fuel operation and with the methyl ester of Jatropha oil as compared to the blend. It increased form 27.4% with neat Jatropha oil to a maximum of 29% with the methyl ester and 28.7% in the dual fuel operation. Smoke was reduced with all methods compared to neat vegetable oil operation. The values of smoke emission are 4.4 Bosch Smoke Units (BSU) with neat Jatropha oil, 4.1 BSU with the blend, 4 BSU with methyl ester of Jatropha oil and 3.5 BSU in the dual fuel operation. The Nitric Oxide (NO) level was lower with Jatropha oil compared to diesel. It was further reduced in dual fuel operation and the blend with methanol. Dual fuel operation showed higher hydrocarbon (HC) and carbon monoxide (CO) emissions than the ester and the blend. Ignition delay was higher with neat Jatropha oil. It increased further with the blend and in dual fuel operation. It was reduced with the ester. Peak pressure and rate of pressure rise were higher with all the methods compared to neat Jatropha oil operation. Jatropha oil and methyl ester showed higher diffusion combustion compared to standard diesel operation. However, dual fuel operation resulted in higher premixed combustion. On the whole it is concluded that transesterification of vegetable oils and methanol induction can significantly enhance the performance of a vegetable oil fuelled diesel engine. © 2003 Elsevier Ltd. All rights reserved.
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    A comprehensive study on performance, emission, and combustion characteristics of a dual-fuel engine fuelled with orange oil and Jatropha oil
    (01-08-2011)
    Senthilkumar, M.
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    Nagalingam, B.
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    Tazerout, M.
    Performance of a single-cylinder, water-cooled, direct-injection diesel engine on dual-fuel operation with Jatropha oil (JO) as pilot fuel and orange oil as primary fuel was evaluated. Constant load test at different power outputs was conducted at the rated speed of 1500 r/min with varying orange oil quantities. The loads were fixed as 20 per cent, 40 per cent, 60 per cent, 80 per cent, and 100 per cent. In dual-fuel operation with orange oil induction, the thermal efficiency of JO was increased mainly at high power outputs. Maximum thermal efficiency with JO was found as 29 per cent at 31 per cent of orange oil induction at 100 per cent load. Smoke was reduced significantly with all orange oil induction rates at all power outputs in dual-fuel operation with JO. It was reduced from 4.4 to 3.3 BSU (Bosch Smoke Units) with JO at the maximum efficiency point at 100 per cent load. HC emissions were increased further at all power outputs in the dual-fuel mode with all rates of orange oil induction. Dual-fuel operation increased the ignition delay of JO. However, peak pressure and energy release rates were improved in the dual-fuel operation with orange oil induction. In general, dual-fuel operation with orange oil as inducted fuel with JO as pilot fuel showed inferior performance and emissions at part loads. It is concluded that the JO as pilots fuel and orange oil as the inducted fuel could be used in diesel engines with reduced smoke levels and improved thermal efficiencies with no major detoriation in performance. © 2011 Authors.
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    Effect of hydrogen induction on the performance of a natural-gas-fuelled lean-burn SI engine
    (01-09-2000)
    Sita Rama Raju, A. V.
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    Nagalingam, B.
    In this experimental study, the effect of inducting small quantities of hydrogen on the performance of a natural-gas-fuelled SI engine operating with very lean fuel-air mixtures was investigated. Tests were conducted at a compression ratio of 12.5 under full throttle conditions. Results indicated the possibility of achieving a significant increase in brake thermal efficiency and reduction in HC and NO by addition of hydrogen because very lean mixtures can be used. It was found that hydrogen addition of the order of 24% is needed to achieve a significant improvement in performance. In general, an increase in the quantity of hydrogen added to natural gas decreases hydrocarbon emission levels, extends the lean misfire limit, decreases ignition delay and combustion duration and leads to higher combustion rates. Hence, it is concluded that adding hydrogen to natural gas is a good method to improve performance and reduce emissions when very lean fuel-air mixtures are used.
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    Effect of compression ratio on the performance and combustion of a biogas fuelled spark ignition engine
    (01-05-2012)
    Porpatham, E.
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    Nagalingam, B.
    A single cylinder diesel engine was modified to operate as a biogas operated spark ignition engine. The engine was operated at 1500 rpm at throttle opening of 25% and 100% at various equivalence ratios. The tests were covered a range of equivalence ratios from rich to the lean operating limit and a number of compression ratios. The spark timing was set to MBT (Minimum advance for Best Torque). The performance, emission and combustion characteristics with different compression ratios are compared. It has been found from the results that the higher the compression ratio, the higher the brake thermal efficiency. When the compression ratio was above a critical value of 13:1, brake power and thermal efficiency increased little. At higher compression ratios above 13:1, increased NOx, HC, and CO emissions were measured. Power and thermal efficiency reached their highest values with the compression ratio between 13:1 and 15:1 and the equivalence ratio between 1.08 and 0.95. Under these conditions, HC and CO emissions were low but the NOx values were high. Power and thermal efficiency reduced for leaner mixtures. The MBT spark timing is retarded with increase in compression ratio. The peak pressure decreases, as the mixture becomes lean at all the compression ratios. The peak pressure is higher with higher compression ratio. Increase in compression ratio leads to high heat release rate. © 2012 Elsevier Ltd. All rights reserved.