The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform
F. N. Alasfour - One of the best experts on this subject based on the ideXlab platform.
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The effect of using 30% iso-butanol-gasoline blend on hydrocarbon emissions from a spark-Ignition engine
Energy Sources, 1999Co-Authors: F. N. AlasfourAbstract:The level of hydrocarbon (HC) emissions, from a spark-Ignition engine using a 30 % iso-butanol-gasoline blend was experimentally investigated. Experiments were conducted on a Hydra single-cylinder, spark-Ignition, Fuel-injection engine. HC emissions were measured as a function of Fuel air equivalence ratio, Ignition timing and engine speed. The effect of varying the temperature of cooling water on HC emissions was also investigated under three Fuel air equivalence ratios (lean, stoichiometric, and rich). Results show that retarding Ignition timing with respect to maximum break torque (MBT) has a great effect on HC emissions reduction, where for lean mixture, Phi 0.85, retarding Ignition timing by 6 degrees from MBT reduces the exhaust HC emissions by 12 %. The level of HC emissions is also reduced by 30 % at MBT, as the cooling water temperature increase from 55 to 90 C. It is noticed that as the engine speed increases, the level of HC emissions decrease.
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NOx EMISSION FROM A SPARK Ignition ENGINE USING 30% ISO-BUTANOL–GASOLINE BLEND: PART 2—Ignition TIMING
Applied Thermal Engineering, 1998Co-Authors: F. N. AlasfourAbstract:The effect of varying Ignition timing on NOx emission, exhaust temperature, knock occurrence and thermal efficiency in a spark Ignition engine has been experimentally investigated. A Hydra single-cylinder, spark-Ignition, Fuel-injection engine was used with a 30% Iso-butanol–gasoline blend as Fuel. The Ignition timing was varied, NOx emission and knocking phenomena were studied at different Fuel–air equivalence ratios. Results show that retarding Ignition timing causes the exhaust temperature to increase. For a lean mixture, advancing Ignition timing has a great effect on the increase of the level of NOx, while for a rich mixture advancing Ignition timing has a minimal effect. Experimental results show that advancing Ignition timing causes the peak of NOx emission to be shifted towards the lean Fuel–air equivalence ratio. Preheating inlet air increases the knock intensity and causes the knock to occur at less advanced Ignition timing. Retarding Ignition timing causes the engine thermal efficiency to decrease.
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Butanol—A single-cylinder engine study: availability analysis
Applied Thermal Engineering, 1997Co-Authors: F. N. AlasfourAbstract:Abstract The availability analysis of a spark-Ignition engine using a butanol-gasoline blend has been experimentally investigated. A Hydra single-cylinder, spark-Ignition, Fuel-injection engine was used over a wide range of Fuel/air equivalence ratios (φ = 0.8–1.2) at a 30% volume butanol-gasoline blend. The goal of this research was to study the effect of using a butanol-gasoline blend in a spark-Ignition engine in terms of first- and second-law efficiency. In addition, the optimal engine conditions of energy utilization were investigated. Results show that, at φ = 0.9, when a butanol-gasoline blend is used, the energy analysis indicates that only 35.4% of the Fuel energy can be utilized as an indicated power, where 64.6% of Fuel energy is not available for conversion to useful work. The availability analysis shows that 50.6% of Fuel energy can be utilized as useful work (34.28% as an indicated power, 12.48% from the exhaust and only 3.84% from the cooling water) and the available energy unaccounted for represents 49.4% of the total available energy.
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BUTANOL—A SINGLE CYLINDER ENGINE STUDY: ENGINE PERFORMANCE
International Journal of Energy Research, 1997Co-Authors: F. N. AlasfourAbstract:The effect of methanol and butanol addition to gasoline on brake specific Fuel consumption (b.s.f.c.), exhaust gas temperature, and thermal efficiency has been experimentally investigated. A Hydra single cylinder, spark Ignition, Fuel injection engine was used over a wide range of Fuel/air equivalence ratio (ϕ=0⋅8 to 1⋅3) for 30% volume alcohol–gasoline blends. The goal of this work is to study the engine performance when methanol and butanol–gasoline blends are used. The performance measurements show that there is an increase in b.s.f.c. when using alcohol–gasoline blends, and b.s.f.c. of a butanol–gasoline blend is less than for a methanol–gasoline blend. The experimental results show that the engine thermal efficiency was decreased when Fueled with alcohol–gasoline blends. It was found that there was about a 4.5% reduction in engine thermal efficiency at ϕ=1⋅0 when 30% butanol was blended with gasoline compared to pure gasoline. The exhaust gas temperature measurements show that there is an increase in temperature in the case of using gasoline as compared to alcohol–gasoline blends, and that the temperature reaches a maximum at ϕ≈1⋅1 when using gasoline and alcohol–gasoline blends. © 1997 by John Wiley & Sons, Ltd.
Magnus Sjoberg - One of the best experts on this subject based on the ideXlab platform.
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effects of egr and its constituents on hcci autoIgnition of ethanol
Proceedings of the Combustion Institute, 2011Co-Authors: Magnus Sjoberg, John E DecAbstract:The thermodynamic and chemical effects of real EGR, simulated EGR, and individual EGR constituents (N2, CO2, and H2O) on the HCCI autoIgnition processes of ethanol have been investigated experimentally and computationally. The results for ethanol were compared in detail with existing data for gasoline, iso-octane, PRF80, and PRF60. The data show that addition of EGR retards the autoIgnition timing for all five Fuels when the intake temperature is maintained constant. However, the amount of retard is dependent on the specific Fuel type, with ethanol showing the lowest sensitivity to the addition of clean simulated EGR gases. The response to EGR can be explained by quantifying the various underlying mechanisms. The results show that the single-stage Ignition Fuel ethanol is quite sensitive to the reduction of compression heating that occurs with EGR due to the higher heat capacity of the EGR gases compared to air. This high sensitivity to the cooling effect of EGR is similar to that of gasoline and iso-octane, which also are single-stage Ignition Fuels under these conditions. On the other hand, ethanol is very insensitive to the reduction of O2 concentration associated with the addition of EGR. Both of these characteristics relate to ethanol’s molecular stability – it does not react much until just before the hot-Ignition point is reached. Consequently, ethanol has a low intermediate-temperature heat-release rate, which leads to a low temperature-rise rate prior to hot Ignition, and therefore a high sensitivity to the cooling effect of EGR. Also, the relative lack of intermediate-temperature heat release prevents [O2] from having much influence on the temperature rise prior to hot Ignition, leading to a low sensitivity of the autoIgnition timing to changes of [O2]. Finally, both H2O and trace species have significant Ignition-enhancing effects for ethanol that to some degree counteract the retarding effect of EGR.
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spectroscopic and chemical kinetic analysis of the phases of hcci autoIgnition and combustion for single and two stage Ignition Fuels
Combustion and Flame, 2008Co-Authors: Wontae Hwang, Joh E Dec, Magnus SjobergAbstract:The temporal phases of autoIgnition and combustion in an HCCI engine have been investigated in both an all-metal engine and a matching optical engine. Gasoline, a primary reference Fuel mixture (PRF80), and several representative real-Fuel constituents were examined. Only PRF80, which is a two-stage Ignition Fuel, exhibited a ''cool-flame'' low-temperature heat-release (LTHR) phase. For all Fuels, slow exothermic reactions occurring at intermediate temperatures raised the charge temperature to the hot-Ignition point. In addition to the amount of LTHR, differences in this intermediate-temperature heat-release (ITHR) phase affect the Fuel Ignition quality. Chemiluminescence images of iso-octane show a weak and uniform light emission during this phase. This is followed by the main high-temperature heat-release (HTHR) phase. Finally, a ''burnout'' phase was observed, with very weak uniform emission and near-zero heat-release rate (HRR). To better understand these combustion phases, chemiluminescence spectroscopy and chemical-kinetic analysis were applied for the single-stage Ignition Fuel, iso-octane, and the two-stage Fuel, PRF80. For both Fuels, the spectrum obtained during the ITHR phase was dominated by formaldehyde chemiluminescence. This was similar to the LTHR spectrum of PRF80, but the emission intensity and the temperature were much higher, indicating differences between the ITHR and LTHR phases. Chemical-kinetic modeling clarified themore » differences and similarities between the LTHR and ITHR phases and the cause of the enhanced ITHR with PRF80. The HTHR spectra for both Fuels were dominated by a broad CO continuum with some contribution from bands of HCO, CH, and OH. The modeling showed that the CO+ O{yields}CO{sub 2}+h{nu} reaction responsible for the CO continuum emission tracks the HTHR well, explaining the strong correlation observed experimentally between the total chemiluminescence and HRR during the HTHR phase. It also showed that the CO continuum does not contribute to the ITHR and LTHR chemiluminescence. Bands of H{sub 2}O and O{sub 2} in the red and IR regions were also detected during the HTHR, which the data indicated were most likely due to thermal excitation. The very weak light emission in the ''burnout'' phase also appeared to be thermal emission from H{sub 2}O and O{sub 2}. (author)« less
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comparing late cycle autoIgnition stability for single and two stage Ignition Fuels in hcci engines
Proceedings of the Combustion Institute, 2007Co-Authors: Magnus Sjoberg, Joh E DecAbstract:Abstract The characteristics of autoIgnition after top-dead-center (TDC) for both single- and two-stage Ignition Fuels have been investigated in a homogeneous charge compression Ignition (HCCI) engine. The single-stage Ignition Fuel was iso-octane and the two-stage Ignition Fuel was PRF80 (80% iso-octane and 20% n -heptane). The results show that the heat-release rate and pressure-rise rate both decrease as the combustion is retarded later into the early expansion stroke. This is an advantage for high-load HCCI operation. However, for both Fuel-types, cycle-to-cycle variations of the Ignition and combustion phasing increase with combustion-phasing retard. Also, the cycle-to-cycle variations are higher for iso-octane compared to PRF80. These observations can be explained by considering the magnitude of random temperature fluctuation and the temperature-rise rate just prior to thermal run-away. Furthermore, too much combustion-phasing retard leads to the appearance of partial-burn or misfire cycles, but the responses of the two Fuels are quite different. The different behaviors can be explained by considering the thermal and chemical state of the residual exhaust gases that are recycled from one cycle to the next. The data indicate that a partial-burn cycle with iso-octane produces residuals that increase the reactivity of the following cycle. However, for the already more reactive PRF80 Fuel, the partial-burn products present in the residuals do not increase the reactivity enough to overcome the retarding effect of cool residual gases.
Ibram Ganesh - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of monophasic Ce_0.5Zr_0.5O_2 solid solution by microwave-induced combustion method
Journal of Materials Science, 2007Co-Authors: Benjaram M. Reddy, Gunugunuri K. Reddy, Ataullah Khan, Ibram GaneshAbstract:Nanocrystalline monophasic Ce_0.5Zr_0.5O_2 solid solution (1:1 molar ratio) has been synthesized by microwave-induced combustion method in a modified domestic microwave oven (2.45 GHz, 700 W) in approximately 40 min from cerium nitrate and zirconium nitrate precursors using urea as Ignition Fuel. For the purpose of better comparison, a Ce_ x Zr_1 − x O_2 solid solution (1:1 molar ratio) was also synthesized by a conventional co-precipitation method from nitrate precursors and subjected to different calcination temperatures. The synthesized powders of both methods were characterized by means of X-ray powder diffraction, thermogravimetry/differential thermal analysis, scanning electron microscopy, and BET surface area techniques. Oxygen storage capacity (OSC) measurements were performed to understand the usefulness of these materials for various applications. The characterization results reveal that the sample obtained by microwave-induced combustion-synthesis route exhibits homogeneous monophasic Ce_0.5Zr_0.5O_2 solid solution whereas the co-precipitated sample displays compositional heterogeneity. The OSC measurements reveal that the materials synthesized by both methods exhibit comparable oxygen vacancy content (δ).
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Synthesis of monophasic Ce0.5Zr0.5O2 solid solution by microwave-induced combustion method
Journal of Materials Science, 2007Co-Authors: Benjaram M. Reddy, Gunugunuri K. Reddy, Ataullah Khan, Ibram GaneshAbstract:Nanocrystalline monophasic Ce0.5Zr0.5O2 solid solution (1:1 molar ratio) has been synthesized by microwave-induced combustion method in a modified domestic microwave oven (2.45 GHz, 700 W) in approximately 40 min from cerium nitrate and zirconium nitrate precursors using urea as Ignition Fuel. For the purpose of better comparison, a CexZr1 − xO2 solid solution (1:1 molar ratio) was also synthesized by a conventional co-precipitation method from nitrate precursors and subjected to different calcination temperatures. The synthesized powders of both methods were characterized by means of X-ray powder diffraction, thermogravimetry/differential thermal analysis, scanning electron microscopy, and BET surface area techniques. Oxygen storage capacity (OSC) measurements were performed to understand the usefulness of these materials for various applications. The characterization results reveal that the sample obtained by microwave-induced combustion-synthesis route exhibits homogeneous monophasic Ce0.5Zr0.5O2 solid solution whereas the co-precipitated sample displays compositional heterogeneity. The OSC measurements reveal that the materials synthesized by both methods exhibit comparable oxygen vacancy content (δ).
Joh E Dec - One of the best experts on this subject based on the ideXlab platform.
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spectroscopic and chemical kinetic analysis of the phases of hcci autoIgnition and combustion for single and two stage Ignition Fuels
Combustion and Flame, 2008Co-Authors: Wontae Hwang, Joh E Dec, Magnus SjobergAbstract:The temporal phases of autoIgnition and combustion in an HCCI engine have been investigated in both an all-metal engine and a matching optical engine. Gasoline, a primary reference Fuel mixture (PRF80), and several representative real-Fuel constituents were examined. Only PRF80, which is a two-stage Ignition Fuel, exhibited a ''cool-flame'' low-temperature heat-release (LTHR) phase. For all Fuels, slow exothermic reactions occurring at intermediate temperatures raised the charge temperature to the hot-Ignition point. In addition to the amount of LTHR, differences in this intermediate-temperature heat-release (ITHR) phase affect the Fuel Ignition quality. Chemiluminescence images of iso-octane show a weak and uniform light emission during this phase. This is followed by the main high-temperature heat-release (HTHR) phase. Finally, a ''burnout'' phase was observed, with very weak uniform emission and near-zero heat-release rate (HRR). To better understand these combustion phases, chemiluminescence spectroscopy and chemical-kinetic analysis were applied for the single-stage Ignition Fuel, iso-octane, and the two-stage Fuel, PRF80. For both Fuels, the spectrum obtained during the ITHR phase was dominated by formaldehyde chemiluminescence. This was similar to the LTHR spectrum of PRF80, but the emission intensity and the temperature were much higher, indicating differences between the ITHR and LTHR phases. Chemical-kinetic modeling clarified themore » differences and similarities between the LTHR and ITHR phases and the cause of the enhanced ITHR with PRF80. The HTHR spectra for both Fuels were dominated by a broad CO continuum with some contribution from bands of HCO, CH, and OH. The modeling showed that the CO+ O{yields}CO{sub 2}+h{nu} reaction responsible for the CO continuum emission tracks the HTHR well, explaining the strong correlation observed experimentally between the total chemiluminescence and HRR during the HTHR phase. It also showed that the CO continuum does not contribute to the ITHR and LTHR chemiluminescence. Bands of H{sub 2}O and O{sub 2} in the red and IR regions were also detected during the HTHR, which the data indicated were most likely due to thermal excitation. The very weak light emission in the ''burnout'' phase also appeared to be thermal emission from H{sub 2}O and O{sub 2}. (author)« less
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comparing late cycle autoIgnition stability for single and two stage Ignition Fuels in hcci engines
Proceedings of the Combustion Institute, 2007Co-Authors: Magnus Sjoberg, Joh E DecAbstract:Abstract The characteristics of autoIgnition after top-dead-center (TDC) for both single- and two-stage Ignition Fuels have been investigated in a homogeneous charge compression Ignition (HCCI) engine. The single-stage Ignition Fuel was iso-octane and the two-stage Ignition Fuel was PRF80 (80% iso-octane and 20% n -heptane). The results show that the heat-release rate and pressure-rise rate both decrease as the combustion is retarded later into the early expansion stroke. This is an advantage for high-load HCCI operation. However, for both Fuel-types, cycle-to-cycle variations of the Ignition and combustion phasing increase with combustion-phasing retard. Also, the cycle-to-cycle variations are higher for iso-octane compared to PRF80. These observations can be explained by considering the magnitude of random temperature fluctuation and the temperature-rise rate just prior to thermal run-away. Furthermore, too much combustion-phasing retard leads to the appearance of partial-burn or misfire cycles, but the responses of the two Fuels are quite different. The different behaviors can be explained by considering the thermal and chemical state of the residual exhaust gases that are recycled from one cycle to the next. The data indicate that a partial-burn cycle with iso-octane produces residuals that increase the reactivity of the following cycle. However, for the already more reactive PRF80 Fuel, the partial-burn products present in the residuals do not increase the reactivity enough to overcome the retarding effect of cool residual gases.
Benjaram M. Reddy - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of monophasic Ce_0.5Zr_0.5O_2 solid solution by microwave-induced combustion method
Journal of Materials Science, 2007Co-Authors: Benjaram M. Reddy, Gunugunuri K. Reddy, Ataullah Khan, Ibram GaneshAbstract:Nanocrystalline monophasic Ce_0.5Zr_0.5O_2 solid solution (1:1 molar ratio) has been synthesized by microwave-induced combustion method in a modified domestic microwave oven (2.45 GHz, 700 W) in approximately 40 min from cerium nitrate and zirconium nitrate precursors using urea as Ignition Fuel. For the purpose of better comparison, a Ce_ x Zr_1 − x O_2 solid solution (1:1 molar ratio) was also synthesized by a conventional co-precipitation method from nitrate precursors and subjected to different calcination temperatures. The synthesized powders of both methods were characterized by means of X-ray powder diffraction, thermogravimetry/differential thermal analysis, scanning electron microscopy, and BET surface area techniques. Oxygen storage capacity (OSC) measurements were performed to understand the usefulness of these materials for various applications. The characterization results reveal that the sample obtained by microwave-induced combustion-synthesis route exhibits homogeneous monophasic Ce_0.5Zr_0.5O_2 solid solution whereas the co-precipitated sample displays compositional heterogeneity. The OSC measurements reveal that the materials synthesized by both methods exhibit comparable oxygen vacancy content (δ).
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Synthesis of monophasic Ce0.5Zr0.5O2 solid solution by microwave-induced combustion method
Journal of Materials Science, 2007Co-Authors: Benjaram M. Reddy, Gunugunuri K. Reddy, Ataullah Khan, Ibram GaneshAbstract:Nanocrystalline monophasic Ce0.5Zr0.5O2 solid solution (1:1 molar ratio) has been synthesized by microwave-induced combustion method in a modified domestic microwave oven (2.45 GHz, 700 W) in approximately 40 min from cerium nitrate and zirconium nitrate precursors using urea as Ignition Fuel. For the purpose of better comparison, a CexZr1 − xO2 solid solution (1:1 molar ratio) was also synthesized by a conventional co-precipitation method from nitrate precursors and subjected to different calcination temperatures. The synthesized powders of both methods were characterized by means of X-ray powder diffraction, thermogravimetry/differential thermal analysis, scanning electron microscopy, and BET surface area techniques. Oxygen storage capacity (OSC) measurements were performed to understand the usefulness of these materials for various applications. The characterization results reveal that the sample obtained by microwave-induced combustion-synthesis route exhibits homogeneous monophasic Ce0.5Zr0.5O2 solid solution whereas the co-precipitated sample displays compositional heterogeneity. The OSC measurements reveal that the materials synthesized by both methods exhibit comparable oxygen vacancy content (δ).
