Natural gas is widely used in sequentially port fuel injection engine to meet stringent emission regulation. Lean burn operation is one of the ways to improve spark-ignition engine fuel economy. The instability in the combustion process of the lean burn engine is one of the major challenges for engine research. In this study, the performance and combustion characteristics of a lean burn sequential injection compressed natural gas (CNG) engine were investigated numerically using computational fluid dynamics (CFD) modeling over a wide range of air/fuel equivalence ratio. A detailed chemical kinetic mechanism was used for natural gas combustion along with laminar flame speed model to capture lean burn operating condition within the combustion chamber. Combustion pressure, indicated mean effective pressure (IMEP), and heat release were analyzed for performance analysis, whereas flame development angle (CA 10), combustion duration, thermal efficiency were taken for combustion analysis. The results show that on increasing air/fuel equivalence ratio at a given spark timing, IMEP decreases as the lean burn mixture produces less amount of gross power output due to insufficient available energy. Moreover, lower burning velocity characteristic of natural gas extends the combustion duration, where a substantial amount of total energy released after top dead center. It is also seen that optimum spark timing (MBT) for maximum IMEP advances with an increase in air/fuel equivalence ratio due to late ignition timing under lean burn condition. CFD model successfully captures the effect of dilution to illustrate the considerations to design future combustion engine for spark ignited natural gas engine.
{"title":"Performance and Combustion Investigation of a Lean Burn Natural Gas Engine Using CFD","authors":"S. Sahoo, Srinibas Tripathy, D. Srivastava","doi":"10.1115/ICEF2018-9613","DOIUrl":"https://doi.org/10.1115/ICEF2018-9613","url":null,"abstract":"Natural gas is widely used in sequentially port fuel injection engine to meet stringent emission regulation. Lean burn operation is one of the ways to improve spark-ignition engine fuel economy. The instability in the combustion process of the lean burn engine is one of the major challenges for engine research. In this study, the performance and combustion characteristics of a lean burn sequential injection compressed natural gas (CNG) engine were investigated numerically using computational fluid dynamics (CFD) modeling over a wide range of air/fuel equivalence ratio. A detailed chemical kinetic mechanism was used for natural gas combustion along with laminar flame speed model to capture lean burn operating condition within the combustion chamber. Combustion pressure, indicated mean effective pressure (IMEP), and heat release were analyzed for performance analysis, whereas flame development angle (CA 10), combustion duration, thermal efficiency were taken for combustion analysis. The results show that on increasing air/fuel equivalence ratio at a given spark timing, IMEP decreases as the lean burn mixture produces less amount of gross power output due to insufficient available energy. Moreover, lower burning velocity characteristic of natural gas extends the combustion duration, where a substantial amount of total energy released after top dead center. It is also seen that optimum spark timing (MBT) for maximum IMEP advances with an increase in air/fuel equivalence ratio due to late ignition timing under lean burn condition. CFD model successfully captures the effect of dilution to illustrate the considerations to design future combustion engine for spark ignited natural gas engine.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117141836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
It is well known that ammonia (NH3) combustion does not produce carbon dioxide (CO2) causing global warming. Therefore, NH3 has received much attention as an alternative diesel fuel for internal combustion engines. On the other hand, it has been reported that the exhaust gas of diesel engine fumigated with NH3 contains unburned NH3 with toxicity for humans and nitrous oxide (N2O) with strong global warming effect. Hence the NH3 and N2O emissions should be reduced to prevent the human health damage and global warming. The aim of this study was to develop the combustion strategies for reducing the unburned NH3 and N2O emissions on diesel engine fumigated with NH3. The experimental results indicated that the higher temperature combustion of NH3 prevents the N2O production and allows itself to react well. From the numerical simulation results, hydrocarbon combustion decomposes NH3 and N2O in ignition processes.
{"title":"Emission and Combustion Characteristics of Diesel Engine Fumigated With Ammonia","authors":"Y. Niki, Y. Nitta, H. Sekiguchi, K. Hirata","doi":"10.1115/ICEF2018-9634","DOIUrl":"https://doi.org/10.1115/ICEF2018-9634","url":null,"abstract":"It is well known that ammonia (NH3) combustion does not produce carbon dioxide (CO2) causing global warming. Therefore, NH3 has received much attention as an alternative diesel fuel for internal combustion engines. On the other hand, it has been reported that the exhaust gas of diesel engine fumigated with NH3 contains unburned NH3 with toxicity for humans and nitrous oxide (N2O) with strong global warming effect. Hence the NH3 and N2O emissions should be reduced to prevent the human health damage and global warming.\u0000 The aim of this study was to develop the combustion strategies for reducing the unburned NH3 and N2O emissions on diesel engine fumigated with NH3. The experimental results indicated that the higher temperature combustion of NH3 prevents the N2O production and allows itself to react well. From the numerical simulation results, hydrocarbon combustion decomposes NH3 and N2O in ignition processes.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"177 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114287000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Engine performance and emissions of a six-stroke Gasoline Compression Ignition (GCI) engine with wide range of Continuously Variable Valve Duration (CVVD) control were numerically investigated at low engine load conditions. For the simulations, an in-house 3-D CFD code with high fidelity physical sub-models was used and the combustion and emissions kinetics were computed using a reduced kinetics mechanism for a 14-component gasoline surrogate fuel. Double injections were employed to effectively form the local fuel/air mixtures with optimal reactivity. Several valve timing and duration variations through the CVVD control were considered under both positive valve overlap (PVO) and negative valve overlap (NVO) conditions. Effects of intake-valve re-breathing between the first expansion and the second compression strokes were also investigated. Close attention was paid to understand the effects of two additional strokes of the engine cycle on the thermal and chemical conditions of charge mixtures that alter ignition, combustion and energy recovery processes. Double injections were found to be necessary to effectively utilize the additional two strokes for the combustion of overly mixed lean charge mixtures during the second power stroke (PS2). It was found that combustion phasing in both power strokes is effectively controlled by the intake valve closure (IVC) timing since it affects the effective compression ratio. Engine operation under NVO condition with fixed exhaust valve opening (EVO) and IVC timings tends to advance the ignition timing of the first power stroke (PS1) but has minimal effect on the ignition timing of PS2. Re-breathing was found to be an effective way to control the ignition timing in PS2 at a slight expense of the combustion efficiency. The operation of a six-stroke GCI engine could be successfully simulated and the operability range of the engine could be substantially extended by employing the CVVD technique. In addition, the control of valve timings could successfully control the thermodynamic and compositional conditions of in-cylinder mixtures that enable to control the combustion phasing.
{"title":"Numerical Analysis of a Six-Stroke Gasoline Compression Ignition (GCI) Engine Combustion With Continuously Variable Valve Duration (CVVD) Control","authors":"Oudumbar Rajput, Y. Ra, K. Ha, Y. Son","doi":"10.1115/ICEF2018-9590","DOIUrl":"https://doi.org/10.1115/ICEF2018-9590","url":null,"abstract":"Engine performance and emissions of a six-stroke Gasoline Compression Ignition (GCI) engine with wide range of Continuously Variable Valve Duration (CVVD) control were numerically investigated at low engine load conditions. For the simulations, an in-house 3-D CFD code with high fidelity physical sub-models was used and the combustion and emissions kinetics were computed using a reduced kinetics mechanism for a 14-component gasoline surrogate fuel. Double injections were employed to effectively form the local fuel/air mixtures with optimal reactivity. Several valve timing and duration variations through the CVVD control were considered under both positive valve overlap (PVO) and negative valve overlap (NVO) conditions. Effects of intake-valve re-breathing between the first expansion and the second compression strokes were also investigated.\u0000 Close attention was paid to understand the effects of two additional strokes of the engine cycle on the thermal and chemical conditions of charge mixtures that alter ignition, combustion and energy recovery processes. Double injections were found to be necessary to effectively utilize the additional two strokes for the combustion of overly mixed lean charge mixtures during the second power stroke (PS2). It was found that combustion phasing in both power strokes is effectively controlled by the intake valve closure (IVC) timing since it affects the effective compression ratio. Engine operation under NVO condition with fixed exhaust valve opening (EVO) and IVC timings tends to advance the ignition timing of the first power stroke (PS1) but has minimal effect on the ignition timing of PS2. Re-breathing was found to be an effective way to control the ignition timing in PS2 at a slight expense of the combustion efficiency.\u0000 The operation of a six-stroke GCI engine could be successfully simulated and the operability range of the engine could be substantially extended by employing the CVVD technique. In addition, the control of valve timings could successfully control the thermodynamic and compositional conditions of in-cylinder mixtures that enable to control the combustion phasing.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129668385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Dahms, M. Reška, M. Püschel, J. Nocke, E. Hassel
The following article details a method for the optimization and improved use of the internal combustion engine as main propulsion. The focus here is not on new propulsion systems or combustion processes, but on the characterization of the typical usage of existing systems in order to enable better utilization. As one major potential for improvement, the transient machinery operation is examined and discussed in this article. Higher fuel consumption and higher emissions occur compared with stationary engine operation in that operation mode. Experimental data from test bed (“Caterpillar MaK 6M20”) measurements are presented which explain the consequences of transient operation. Furthermore, appropriate analyzing methods to evaluate this operation mode are shown. Finally, a modelling approach is presented using the data for calibration and validation of an engine simulation model. The most significant part to predict real transient efficiency and emissions is the in-cylinder process and especially its combustion process. Therefore, the simulation model does not use engine maps but a mostly physically based engine model by using thermodynamic approaches and chemical reaction kinetics. The specific application of that simulation model for four-stroke medium-speed engines covers the behavior of transient operation during ship maneuverings since it is developed for integration into a ship engine simulator.
{"title":"Fuel Consumption and Emissions in Transient Operation During Ship Maneuvering","authors":"F. Dahms, M. Reška, M. Püschel, J. Nocke, E. Hassel","doi":"10.1115/ICEF2018-9602","DOIUrl":"https://doi.org/10.1115/ICEF2018-9602","url":null,"abstract":"The following article details a method for the optimization and improved use of the internal combustion engine as main propulsion. The focus here is not on new propulsion systems or combustion processes, but on the characterization of the typical usage of existing systems in order to enable better utilization.\u0000 As one major potential for improvement, the transient machinery operation is examined and discussed in this article. Higher fuel consumption and higher emissions occur compared with stationary engine operation in that operation mode. Experimental data from test bed (“Caterpillar MaK 6M20”) measurements are presented which explain the consequences of transient operation. Furthermore, appropriate analyzing methods to evaluate this operation mode are shown. Finally, a modelling approach is presented using the data for calibration and validation of an engine simulation model.\u0000 The most significant part to predict real transient efficiency and emissions is the in-cylinder process and especially its combustion process. Therefore, the simulation model does not use engine maps but a mostly physically based engine model by using thermodynamic approaches and chemical reaction kinetics. The specific application of that simulation model for four-stroke medium-speed engines covers the behavior of transient operation during ship maneuverings since it is developed for integration into a ship engine simulator.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129828783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Aniello, L. Bartolucci, S. Cordiner, V. Mulone, S. Krishnan, K. Srinivasan
Over the last few decades, emissions regulations for internal combustion engines have become increasingly restrictive, pushing researchers around the world to exploit innovative propulsion solutions. Among them, the dual fuel low temperature combustion (LTC) strategy has proven capable of reducing fuel consumption and while meeting emissions regulations for oxides of nitrogen (NOx) and particulate matter (PM) without problematic aftertreatment systems. However, further investigations are still needed to reduce engine-out hydrocarbon (HC) and carbon monoxide (CO) emissions as well as to extend the operational range and to further improve the performance and efficiency of dual-fuel engines. In this scenario, the present study focuses on numerical simulation of fumigated methane-diesel dual fuel LTC in a single-cylinder research engine (SCRE) operating at low load and high methane percent energy substitution (PES). Results are validated against experimental cylinder pressure and apparent heat release rate (AHRR) data. A 3D full-cylinder RANS simulation is used to thoroughly understand the influence of the start of injection (SOI) of diesel fuel on the overall combustion behavior, clarifying the causes of AHRR transition from two-stage AHRR at late SOIs to single-stage AHRR at early SOIs, low temperature heat release (LTHR) behavior, as well as high HC production. The numerical campaign shows that it is crucial to reliably represent the interaction between the diesel spray and the in-cylinder charge to match both local and overall methane energy fraction, which in turn, ensures a proper representation of the whole combustion. To that aim, even a slight deviation (∼3%) of the trapped mass or of the thermodynamic conditions would compromise the numerical accuracy, highlighting the importance of properly capturing all the phenomena occurring during the engine cycle. The comparison between numerical and experimental AHRR curves shows the capability of the numerical framework proposed to correctly represent the dual-fuel combustion process, including low temperature heat release (LTHR) and the transition from two-stage to single stage AHRR with advancing SOI. The numerical simulations allow for quantitative evaluation of the residence time of vapor-phase diesel fuel inside the combustion chamber and at the same time tracking the evolution of local diesel mass fraction during ignition delay — showing their influence on the LTHR phenomena. Oxidation regions of diesel and ignition points of methane are also displayed for each case, clarifying the reasons for the observed differences in combustion evolution at different SOIs.
{"title":"CFD Analysis of Diesel-Methane Dual Fuel Low Temperature Combustion at Low Load and High Methane Substitution","authors":"A. Aniello, L. Bartolucci, S. Cordiner, V. Mulone, S. Krishnan, K. Srinivasan","doi":"10.1115/ICEF2018-9649","DOIUrl":"https://doi.org/10.1115/ICEF2018-9649","url":null,"abstract":"Over the last few decades, emissions regulations for internal combustion engines have become increasingly restrictive, pushing researchers around the world to exploit innovative propulsion solutions. Among them, the dual fuel low temperature combustion (LTC) strategy has proven capable of reducing fuel consumption and while meeting emissions regulations for oxides of nitrogen (NOx) and particulate matter (PM) without problematic aftertreatment systems. However, further investigations are still needed to reduce engine-out hydrocarbon (HC) and carbon monoxide (CO) emissions as well as to extend the operational range and to further improve the performance and efficiency of dual-fuel engines.\u0000 In this scenario, the present study focuses on numerical simulation of fumigated methane-diesel dual fuel LTC in a single-cylinder research engine (SCRE) operating at low load and high methane percent energy substitution (PES). Results are validated against experimental cylinder pressure and apparent heat release rate (AHRR) data. A 3D full-cylinder RANS simulation is used to thoroughly understand the influence of the start of injection (SOI) of diesel fuel on the overall combustion behavior, clarifying the causes of AHRR transition from two-stage AHRR at late SOIs to single-stage AHRR at early SOIs, low temperature heat release (LTHR) behavior, as well as high HC production.\u0000 The numerical campaign shows that it is crucial to reliably represent the interaction between the diesel spray and the in-cylinder charge to match both local and overall methane energy fraction, which in turn, ensures a proper representation of the whole combustion. To that aim, even a slight deviation (∼3%) of the trapped mass or of the thermodynamic conditions would compromise the numerical accuracy, highlighting the importance of properly capturing all the phenomena occurring during the engine cycle.\u0000 The comparison between numerical and experimental AHRR curves shows the capability of the numerical framework proposed to correctly represent the dual-fuel combustion process, including low temperature heat release (LTHR) and the transition from two-stage to single stage AHRR with advancing SOI. The numerical simulations allow for quantitative evaluation of the residence time of vapor-phase diesel fuel inside the combustion chamber and at the same time tracking the evolution of local diesel mass fraction during ignition delay — showing their influence on the LTHR phenomena. Oxidation regions of diesel and ignition points of methane are also displayed for each case, clarifying the reasons for the observed differences in combustion evolution at different SOIs.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128476817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. McTaggart-Cowan, Jian Huang, Marco Turcios, Ashish Singh, S. Munshi
Non-premixed combustion of directly-injected natural gas offers diesel-like performance and efficiency with lower fuel costs and reduced greenhouse gas emissions. To ignite the fuel, a separate ignition source is needed. This work reports on the initial development of a new hot-surface based ignitor, where a small quantity of natural gas is injected and ignited by a hot element. This generates a robust pilot flame to ignite the main gas injection. A series of experimental tests were conducted to evaluate the sensitivity of the pilot flame formation process to hot surface temperature and geometry and to gas pilot injection geometry. Tests were conducted in a constant-volume combustion chamber at up to 6 bar with hot surface temperatures up to 1750 K. Reacting-flow computational fluid dynamics (CFD) evaluation is used to help interpret the results and to extrapolate to engine-relevant pressures. The results show that hot surface temperatures around 1500 K can minimize the pilot ignition time. An injector geometry where the pilot gas jets are angled such that they impinge on the hot surface but retain sufficient momentum to convect mass into the main chamber helps to ensure rapid and stable ignition. The CFD results indicate that, at engine pressures, a stable gas pilot flame could be established within 1–2 ms using the proposed injector geometry. These results will be used to underpin further development activities on this concept.
{"title":"Evaluation of a Hot-Surface Ignition System for a Direct-Injection of Natural Gas Engine","authors":"G. McTaggart-Cowan, Jian Huang, Marco Turcios, Ashish Singh, S. Munshi","doi":"10.1115/ICEF2018-9734","DOIUrl":"https://doi.org/10.1115/ICEF2018-9734","url":null,"abstract":"Non-premixed combustion of directly-injected natural gas offers diesel-like performance and efficiency with lower fuel costs and reduced greenhouse gas emissions. To ignite the fuel, a separate ignition source is needed. This work reports on the initial development of a new hot-surface based ignitor, where a small quantity of natural gas is injected and ignited by a hot element. This generates a robust pilot flame to ignite the main gas injection. A series of experimental tests were conducted to evaluate the sensitivity of the pilot flame formation process to hot surface temperature and geometry and to gas pilot injection geometry. Tests were conducted in a constant-volume combustion chamber at up to 6 bar with hot surface temperatures up to 1750 K. Reacting-flow computational fluid dynamics (CFD) evaluation is used to help interpret the results and to extrapolate to engine-relevant pressures. The results show that hot surface temperatures around 1500 K can minimize the pilot ignition time. An injector geometry where the pilot gas jets are angled such that they impinge on the hot surface but retain sufficient momentum to convect mass into the main chamber helps to ensure rapid and stable ignition. The CFD results indicate that, at engine pressures, a stable gas pilot flame could be established within 1–2 ms using the proposed injector geometry. These results will be used to underpin further development activities on this concept.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"272 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124401380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ahmed I. El-Seesy, H. Hassan, A. Dawood, A. Attia, H. Kosaka, S. Ookawara
In this experimental examination, an attempt was made to improve the performance and diminish the exhaust emissions by adding titanium oxide (TiO2) nanoparticles into J30D5H blend (5% by volume n-hexane, 30% by volume jojoba methyl ester, and 65% by volume diesel fuel) under various engine loads and a constant speed of 2000 rpm. The titanium oxide nanoparticles were added to J30D5H blend at two proportions, including 25 mg/l and 50 mg/l by using an ultrasonic technique. The addition of TiO2 into J30D5H led to a significant improvement in the engine performance, where the brake specific fuel consumption was reduced by 12%, while the brake thermal efficiency was increased by 15% compared to J30D5H blend. The combustion consequences for the J30D5H blend with nanoparticles addition exhibited that the peak pressure and maximum heat release rate were increased by approximately 4.5% and 2%, respectively. Moreover, the CO and UHC emissions were reduced by 20% and 50%, respectively. Nevertheless, the NOx emission was increased by about 15% with adding TiO2 into J30D5H blend.
{"title":"Investigation of the Impact of Adding Titanium Dioxide to Jojoba Biodiesel-Diesel-N-Hexane Mixture on the Performance and Emission Characteristics of a Diesel Engine","authors":"Ahmed I. El-Seesy, H. Hassan, A. Dawood, A. Attia, H. Kosaka, S. Ookawara","doi":"10.1115/ICEF2018-9647","DOIUrl":"https://doi.org/10.1115/ICEF2018-9647","url":null,"abstract":"In this experimental examination, an attempt was made to improve the performance and diminish the exhaust emissions by adding titanium oxide (TiO2) nanoparticles into J30D5H blend (5% by volume n-hexane, 30% by volume jojoba methyl ester, and 65% by volume diesel fuel) under various engine loads and a constant speed of 2000 rpm. The titanium oxide nanoparticles were added to J30D5H blend at two proportions, including 25 mg/l and 50 mg/l by using an ultrasonic technique. The addition of TiO2 into J30D5H led to a significant improvement in the engine performance, where the brake specific fuel consumption was reduced by 12%, while the brake thermal efficiency was increased by 15% compared to J30D5H blend. The combustion consequences for the J30D5H blend with nanoparticles addition exhibited that the peak pressure and maximum heat release rate were increased by approximately 4.5% and 2%, respectively. Moreover, the CO and UHC emissions were reduced by 20% and 50%, respectively. Nevertheless, the NOx emission was increased by about 15% with adding TiO2 into J30D5H blend.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114772555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ozone assisted combustion has shown promise in stabilizing combustion and extending operating range of internal combustion engines. However, it has been reported that sensitivity of ozone quantity on combustion varies significantly dependent on combustion modes. For example, auto-ignition driv3en combustion in homogeneous charge compression ignition (HCCI) engine was found to be highly sensitive to the ozone concentration, and up to 100 PPM was found to be sufficient to promote combustion. On the other hand, flame propagation in spark-ignited (SI) engine has been reported to be much less sensitive to the ozone amount, requiring ozone concentration about 3000∼6000 PPM to realize any benefit in the flame speed. A better understanding on the ozone sensitivity is required for combustion device design with ozone addition. In this study, a Damköhler number analysis was performed to analyze the vast difference in the ozone sensitivity between auto-ignition and flame propagation. The analysis showed that, for ozone to be effective in flame propagation, the contribution of ozone on chemistry should be large enough to overcome the diffused radical from the oxidation layer. It is expected that similar analysis will be applicable to any additives to provide an understanding of their effect.
{"title":"Damköhler Number Analysis on the Effect of Ozone on Auto-Ignition and Flame Propagation in Internal Combustion Engines","authors":"SeungHwan Keum, T. Kuo","doi":"10.1115/ICEF2018-9559","DOIUrl":"https://doi.org/10.1115/ICEF2018-9559","url":null,"abstract":"Ozone assisted combustion has shown promise in stabilizing combustion and extending operating range of internal combustion engines. However, it has been reported that sensitivity of ozone quantity on combustion varies significantly dependent on combustion modes. For example, auto-ignition driv3en combustion in homogeneous charge compression ignition (HCCI) engine was found to be highly sensitive to the ozone concentration, and up to 100 PPM was found to be sufficient to promote combustion. On the other hand, flame propagation in spark-ignited (SI) engine has been reported to be much less sensitive to the ozone amount, requiring ozone concentration about 3000∼6000 PPM to realize any benefit in the flame speed. A better understanding on the ozone sensitivity is required for combustion device design with ozone addition. In this study, a Damköhler number analysis was performed to analyze the vast difference in the ozone sensitivity between auto-ignition and flame propagation. The analysis showed that, for ozone to be effective in flame propagation, the contribution of ozone on chemistry should be large enough to overcome the diffused radical from the oxidation layer. It is expected that similar analysis will be applicable to any additives to provide an understanding of their effect.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128192139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Major interests in the automotive industry include the use of alternative fuels and reduced fuel usage to address fuel supply security concerns and regulatory requirements. The majority of previous internal combustion engine (ICE) control strategies consider only the First Law of Thermodynamics (FLT). However, FLT is not able to distinguish losses in work potential due to irreversibilities, e.g., up to 25% of fuel exergy may be lost to irreversibilities. To account for these losses, the Second Law of Thermodynamics (SLT) is applicable. The SLT is used to identify the quality of an energy source via availability since not all the energy in a particular energy source is available to produce work; therefore optimal control that includes availability may be another path toward reduced fuel use. Herein, Model Predictive Control (MPC) is developed for both FLT and SLT approaches where fuel consumption is minimized in the former and availability destruction in the latter. Additionally, both include minimization of load tracking error. The controls are evaluated in the simulation of a single cylinder naturally aspirated compression ignition engine that is fueled with either 20% biodiesel and 80% diesel blend or diesel only. Control simulations at a constant engine speed and changing load profile show that the SLT approach results in higher SLT efficiency, reduced specific fuel consumption, and decreased NOx emissions. Further, compared to use of diesel only, use of the biodiesel blend resulted in less SLT efficiency, higher specific fuel consumption, and lower NOx emissions.
{"title":"CI Engine Model Predictive Control With Availability Destruction Minimization","authors":"Muataz Abotabik, Richard T. Meyer","doi":"10.1115/ICEF2018-9673","DOIUrl":"https://doi.org/10.1115/ICEF2018-9673","url":null,"abstract":"Major interests in the automotive industry include the use of alternative fuels and reduced fuel usage to address fuel supply security concerns and regulatory requirements. The majority of previous internal combustion engine (ICE) control strategies consider only the First Law of Thermodynamics (FLT). However, FLT is not able to distinguish losses in work potential due to irreversibilities, e.g., up to 25% of fuel exergy may be lost to irreversibilities. To account for these losses, the Second Law of Thermodynamics (SLT) is applicable. The SLT is used to identify the quality of an energy source via availability since not all the energy in a particular energy source is available to produce work; therefore optimal control that includes availability may be another path toward reduced fuel use. Herein, Model Predictive Control (MPC) is developed for both FLT and SLT approaches where fuel consumption is minimized in the former and availability destruction in the latter. Additionally, both include minimization of load tracking error. The controls are evaluated in the simulation of a single cylinder naturally aspirated compression ignition engine that is fueled with either 20% biodiesel and 80% diesel blend or diesel only. Control simulations at a constant engine speed and changing load profile show that the SLT approach results in higher SLT efficiency, reduced specific fuel consumption, and decreased NOx emissions. Further, compared to use of diesel only, use of the biodiesel blend resulted in less SLT efficiency, higher specific fuel consumption, and lower NOx emissions.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114602344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ryan O’Donnell, Tommy R. Powell, Z. Filipi, Mark A. Hoffman
The application of a Thermal Barrier Coating (TBC) to combustion chamber surfaces within a Low Temperature Combustion (LTC) engine alters conditions at the gas-wall boundary and affects the temperature field of the interior charge. Thin, low-conductivity, TBCs (∼150μm) exhibit elevated surface temperatures during late compression and expansion processes. This temperature ‘swing’ reduces gas-to-wall heat transfer during combustion and expansion, alters reaction rates in the wall affected zones, and improves thermal efficiency. In this paper, Thermal Stratification Analysis (TSA) is employed to quantify the impact of Thermal Barrier Coatings on the charge temperature distribution within a gasoline-fueled Homogeneous Charge Compression Ignition (HCCI) engine. Using an empirically derived ignition delay correlation for HCCI-relevant air-to-fuel ratios, an autoignition integral is tracked across multiple temperature ‘zones’. Charge mass is assigned to each zone by referencing the Mass Fraction Burn (MFB) profile from the corresponding heat release analysis. Closed-cycle temperature distributions are generated for baseline (i.e., ‘metal’) and TBC-treated engine configurations. In general, the TBC-treated engine configurations are shown to maintain a higher percentage of charge mass at temperatures approximating the isentropic limit.
{"title":"Assessing the Impact of Thermal Barrier Coatings on Charge Temperature Stratification Within a Homogeneous Charge Compression Ignition Engine","authors":"Ryan O’Donnell, Tommy R. Powell, Z. Filipi, Mark A. Hoffman","doi":"10.1115/ICEF2018-9762","DOIUrl":"https://doi.org/10.1115/ICEF2018-9762","url":null,"abstract":"The application of a Thermal Barrier Coating (TBC) to combustion chamber surfaces within a Low Temperature Combustion (LTC) engine alters conditions at the gas-wall boundary and affects the temperature field of the interior charge. Thin, low-conductivity, TBCs (∼150μm) exhibit elevated surface temperatures during late compression and expansion processes. This temperature ‘swing’ reduces gas-to-wall heat transfer during combustion and expansion, alters reaction rates in the wall affected zones, and improves thermal efficiency. In this paper, Thermal Stratification Analysis (TSA) is employed to quantify the impact of Thermal Barrier Coatings on the charge temperature distribution within a gasoline-fueled Homogeneous Charge Compression Ignition (HCCI) engine. Using an empirically derived ignition delay correlation for HCCI-relevant air-to-fuel ratios, an autoignition integral is tracked across multiple temperature ‘zones’. Charge mass is assigned to each zone by referencing the Mass Fraction Burn (MFB) profile from the corresponding heat release analysis. Closed-cycle temperature distributions are generated for baseline (i.e., ‘metal’) and TBC-treated engine configurations. In general, the TBC-treated engine configurations are shown to maintain a higher percentage of charge mass at temperatures approximating the isentropic limit.","PeriodicalId":441369,"journal":{"name":"Volume 1: Large Bore Engines; Fuels; Advanced Combustion","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115370394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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