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Gregory M. Shaver - One of the best experts on this subject based on the ideXlab platform.
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Utilizing Production Viable Valve Strategies at Elevated Speeds and Loads to Improve Volumetric Efficiency via Intake Valve Modulation
Frontiers in Mechanical Engineering, 2018Co-Authors: Kalen R Vos, Gregory M. Shaver, James Mccarthy, Lisa FarrellAbstract:Valvetrain flexibility enables the optimization of the engine’s ability to breathe across the operating range, resulting in more efficient operation. The authors have shown the merit of improving volumetric efficiency via Valvetrain flexibility to improve fuel efficiency at elevated engine speeds in previous work. This study focuses on production viable solutions targeting similar volumetric efficiency benefits via delayed Intake Valve closure at these elevated engine speeds. Specifically, the production viable solutions include reducing the duration at peak lift, as well as reducing the amount of hardware required to achieve a delayed Intake closure timing. It is demonstrated through simulation that delayed Intake Valve modulation at an elevated speed (2200 RPM) and load (12.7 bar BMEP) is capable of improving volumetric efficiency via a production viable lost motion enabled boot profile shape. Phased and dwell profiles were also evaluated. These profiles were compared against each other for two separately simulated cases: 1) modulating both Intake Valves per cylinder, and 2) modulating one of the two Intake Valves per cylinder. The boot, phase, and dwell profiles demonstrate volumetric efficiency improvements of up to 3.33%, 3.41%, and 3.5% respectively for two Valve modulation, while realizing 2.79%, 2.59%, and 3.01% respectively for single Valve modulation. As a result, this paper demonstrates that nearly all of the volumetric efficiency benefits achieved while modulating IVC via dwell profiles are possible with production viable boot and phased profiles
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Oxygen fraction estimation for diesel engines utilizing variable Intake Valve actuation
2012 American Control Conference (ACC), 2012Co-Authors: Lyle E. Kocher, D. G. Van Alstine, Ed Koeberlein, Karla Stricker, Gregory M. ShaverAbstract:Advanced diesel engine architectures employing flexible Valve trains enable emissions reductions and fuel economy improvements through advanced combustion strategies. These combustion strategies, such as pre-mixed charge compression ignition (PCCI), homogenous charge compression ignition (HCCI) and low temperature combustion (LTC), are controlled and enabled through the use of flexible Valve trains. The in-cylinder oxygen concentration serves as a critical input in controlling these strategies. Unfortunately, the in-cylinder oxygen concentration is extremely difficult to measure on production engines. However, the oxygen concentrations in the Intake and exhaust manifold can be utilized to calculate the in-cylinder oxygen concentration when the charge and residual in-cylinder mass are available. A model-based observer is developed to estimate the oxygen concentration in the Intake and exhaust manifolds. The oxygen concentration estimates will be sensitive to errors in the mass flows of the manifold filling dynamics. To improve the EGR flow measurement, a high-gain observer is implemented to provide a more accurate EGR flow estimate. The observer estimates the oxygen concentrations to within 0.5% O2 and converges in less than 0.5 seconds.
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Effective compression ratio estimation in engines with flexible Intake Valve actuation
2012 American Control Conference (ACC), 2012Co-Authors: Karla Stricker, Lyle Kocher, Ed Koeberlein, D. G. Van Alstine, Gregory M. ShaverAbstract:The ability to modulate the effective compression ratio (ECR) of an engine is a key enabler of advanced combustion strategies. ECR is a measure of the effective in-cylinder compression of gases above Intake manifold conditions. An engine's ECR is usually computed from in-cylinder pressure data, requiring reliable in-cylinder pressure sensors that are not typically found on production engines. As such, a method is needed for determining the effective compression ratio using only information available from stock engine sensors, including manifold pressures and temperatures and air flows. The work outlined here presents a strategy for estimating the ECR without need for in-cylinder pressure data. The estimation scheme was transiently tested and compared to experimental engine data from a unique diesel engine test bed with flexible Intake Valve actuation, and was able to converge within 3 engine cycles after a transient event with less than 6% average steady-state error compared to experimental engine data.
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physically based volumetric efficiency model for diesel engines utilizing variable Intake Valve actuation
International Journal of Engine Research, 2012Co-Authors: Lyle Kocher, Ed Koeberlein, D. G. Van Alstine, Karla Stricker, Gregory M. ShaverAbstract:Advanced diesel engine architectures employing flexible Valve trains enable emissions reductions and fuel economy improvements. Flexibility in the Valve train allows engine designers to optimize th...
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Estimation of effective compression ratio for engines utilizing flexible Intake Valve actuation
Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 2012Co-Authors: Karla Stricker, Lyle Kocher, Ed Koeberlein, D. G. Van Alstine, Gregory M. ShaverAbstract:Modulation of the effective compression ratio, a measure of the amount of compression of in-cylinder gases above Intake manifold conditions, is a key enabler of advanced combustion strategies aimed at reducing emissions while maintaining efficiency, and is directly influenced by modulation of Intake Valve closing time. To date, the effective compression ratio has most commonly been calculated from in-cylinder pressure data, requiring reliable in-cylinder pressure sensors. These sensors are generally not found on production engines, and thus a method is needed to determine effective compression ratio without in-cylinder pressure data. The work presented here outlines an estimation scheme that combines a high-gain observer with a physically-based volumetric efficiency model to estimate effective compression ratio using only information available from stock engine sensors, including manifold pressures and temperatures and air flows. The estimation scheme is compared to experimental engine data from a unique ...
Rolf D Reitz - One of the best experts on this subject based on the ideXlab platform.
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ICES2005-1020 MODELING THE EFFECTS OF VARIABLE Intake Valve TIMING ON DIESEL HCCI COMBUSTION AT VARYING LOAD, SPEED AND BOOST PRESSURES
2020Co-Authors: Caroline L Dougan, Songcharng Kong, Rolf D ReitzAbstract:ABSTRACT It is well known that homogeneous charge compression ignition (HCCI) operated engines have the potential to provide the efficiency of a typical diesel engine, but with very low NOx and Particulate Matter (PM) emissions. One of the main challenges with this type of engine, however, is that it can be difficult to control the combustion event, especially at high loads. The development of Variable Valve Timing (VVT) technology may offer an important advantage in the ability to control HCCI combustion. This work investigates the potential of using late Intake Valve closure times to delay auto-ignition and to expand the HCCI operation range through proper combustion control. A multi-dimensional KIVA/Chemkin model is used in conjunction with detailed chemical kinetics, based on an available n-heptane mechanism. The model is used to evaluate the effectiveness of late Intake Valve times as load, speed, and boost pressure conditions are varied. Furthermore, a larger understanding of diesel HCCI combustion is sought by investigating the major parameters affecting combustion control under these various operating conditions
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effects of late Intake Valve closing livc and rebreathing Valve strategies on diesel engine performance and emissions at low loads
Applied Thermal Engineering, 2016Co-Authors: Xiangyu Zhang, Rolf D Reitz, Hu Wang, Zunqing Zheng, Mingfa YaoAbstract:Abstract An experimental study has been conducted to explore the effects of five different Valve strategies, including three Intake Valve closure (IVC) timing strategies and two rebreathing strategies (i.e., second opening of the Intake/exhaust Valves during the exhaust/Intake processes, called 2IVO and 2EVO) on the combustion and emission characteristics at various low loads (1–5 bar gross indicated mean effective pressure, IMEP g ) on a heavy-duty diesel engine. Then proper Valve strategies to achieve clean combustion (Engine-out emission: NO x ~0.4 g/kW-hr, Smoke x emissions within low levels, the externally cooled exhaust gas recirculation (Ex-EGR) was used and combined with three IVC strategies in this study, while internal EGR (In-EGR) was used with 2IVO and 2EVO strategies. The results show that low NO x emissions can be achieved for these Valve strategies with high In-EGR or Ex-EGR. However, the differences among various Valve strategies on other emissions (CO, HC and Smoke) and combustion characteristics are sensitive to engine loads. Improved combustion and emissions can be achieved with rebreathing strategies at low loads (1–2 bar IMEP g ), however, higher Smoke emissions and lower thermal efficiency are observed at higher loads. The lowest Smoke emissions can be obtained with the late IVC strategy, but at the same time with high CO and HC emissions, especially at lower loads. The suggestion is to use the rebreathing Valve strategies at lower engine load from 1 to 2 bar IMEP g and then change to the standard and late IVC strategies at higher loads.
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the potential of high load extension by using late Intake Valve closing for a diesel premixed charge compression ignition pcci engine
Energy Procedia, 2015Co-Authors: Ming Jia, Hu Wang, Tianyou Wang, Maozhao Xie, Rolf D ReitzAbstract:Abstract Premixed charge compression ignition (PCCI) combustion is capable of reducing nitrogen oxides (NO x ) and soot emissions simultaneously, while remaining high fuel efficiency. Whereas, PCCI combustion still faces the challenges of the control of ignition timing and the expansion of operating range. In this study, by coupling a multi-dimensional computational fluid dynamics (CFD) code and genetic algorithm (GA), the potential of high-load expansion by using late Intake Valve closing (IVC) was explored in a light-duty diesel PCCI engine. It was revealed that low fuel consumption, and low NO x and soot emissions could be achieved with the employment of retarded IVC timing, high EGR rate, boosted Intake pressure, and optimized injection timing.
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Numerical study on the low emission window of homogeneous charge compression ignition diesel combustion
Combustion Science and Technology, 2007Co-Authors: Sung Wook Park, Rolf D ReitzAbstract:Abstract This article describes a numerical study of the low emission window (lower than 10 g/kg-f CO, 10 g/kg-f HC, 0.5 g/kg-f NO and almost soot-less) of diesel HCCI combustion. In order to locate low emission operating conditions, parametric calculations were performed over wide ranges by changing equivalence ratio, inlet temperature, Intake Valve closure timing, engine speed and fuel amount under the assumption of ideal homogeneous charge. The CO, HC, NO and soot emissions are summarized on equivalence ratio-peak cycle temperature maps, and the low emission region was found to be located in the region approximately from 1,600 K to 1,800 K peak cycle temperature, and on the lean side of stoichiometric equivalence ratio. In addition, it is revealed that clean HCCI combustion is possible with reduced EGR levels by retarding the Intake Valve closure timing, and the low emission window moves toward higher temperatures as engine speed is increased.
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modeling the effects of variable Intake Valve timing on diesel hcci combustion at varying load speed and boost pressures
Journal of Engineering for Gas Turbines and Power-transactions of The Asme, 2005Co-Authors: Caroline L Genzale, Songcharng Kong, Rolf D ReitzAbstract:It is well known that homogeneous charge compression ignition (HCCI) operated engines have the potential to provide the efficiency of a typical diesel engine, but with very low NOx and Particulate Matter (PM) emissions. One of the main challenges with this type of engine, however, is that it can be difficult to control the combustion event, especially at high loads. The development of Variable Valve Timing (VVT) technology may offer an important advantage in the ability to control HCCI combustion. This work investigates the potential of using late Intake Valve closure times to delay auto-ignition and to expand the HCCI operation range through proper combustion control. A multi-dimensional KIVA/Chemkin model is used in conjunction with detailed chemical kinetics, based on an available n-heptane mechanism. The model is used to evaluate the effectiveness of late Intake Valve times as load, speed, and boost pressure conditions are varied. Furthermore, a larger understanding of diesel HCCI combustion is sought by investigating the major parameters affecting combustion control under these various operating conditions.Copyright © 2005 by ASME
Karla Stricker - One of the best experts on this subject based on the ideXlab platform.
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Oxygen fraction estimation for diesel engines utilizing variable Intake Valve actuation
2012 American Control Conference (ACC), 2012Co-Authors: Lyle E. Kocher, D. G. Van Alstine, Ed Koeberlein, Karla Stricker, Gregory M. ShaverAbstract:Advanced diesel engine architectures employing flexible Valve trains enable emissions reductions and fuel economy improvements through advanced combustion strategies. These combustion strategies, such as pre-mixed charge compression ignition (PCCI), homogenous charge compression ignition (HCCI) and low temperature combustion (LTC), are controlled and enabled through the use of flexible Valve trains. The in-cylinder oxygen concentration serves as a critical input in controlling these strategies. Unfortunately, the in-cylinder oxygen concentration is extremely difficult to measure on production engines. However, the oxygen concentrations in the Intake and exhaust manifold can be utilized to calculate the in-cylinder oxygen concentration when the charge and residual in-cylinder mass are available. A model-based observer is developed to estimate the oxygen concentration in the Intake and exhaust manifolds. The oxygen concentration estimates will be sensitive to errors in the mass flows of the manifold filling dynamics. To improve the EGR flow measurement, a high-gain observer is implemented to provide a more accurate EGR flow estimate. The observer estimates the oxygen concentrations to within 0.5% O2 and converges in less than 0.5 seconds.
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Effective compression ratio estimation in engines with flexible Intake Valve actuation
2012 American Control Conference (ACC), 2012Co-Authors: Karla Stricker, Lyle Kocher, Ed Koeberlein, D. G. Van Alstine, Gregory M. ShaverAbstract:The ability to modulate the effective compression ratio (ECR) of an engine is a key enabler of advanced combustion strategies. ECR is a measure of the effective in-cylinder compression of gases above Intake manifold conditions. An engine's ECR is usually computed from in-cylinder pressure data, requiring reliable in-cylinder pressure sensors that are not typically found on production engines. As such, a method is needed for determining the effective compression ratio using only information available from stock engine sensors, including manifold pressures and temperatures and air flows. The work outlined here presents a strategy for estimating the ECR without need for in-cylinder pressure data. The estimation scheme was transiently tested and compared to experimental engine data from a unique diesel engine test bed with flexible Intake Valve actuation, and was able to converge within 3 engine cycles after a transient event with less than 6% average steady-state error compared to experimental engine data.
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physically based volumetric efficiency model for diesel engines utilizing variable Intake Valve actuation
International Journal of Engine Research, 2012Co-Authors: Lyle Kocher, Ed Koeberlein, D. G. Van Alstine, Karla Stricker, Gregory M. ShaverAbstract:Advanced diesel engine architectures employing flexible Valve trains enable emissions reductions and fuel economy improvements. Flexibility in the Valve train allows engine designers to optimize th...
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Estimation of effective compression ratio for engines utilizing flexible Intake Valve actuation
Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 2012Co-Authors: Karla Stricker, Lyle Kocher, Ed Koeberlein, D. G. Van Alstine, Gregory M. ShaverAbstract:Modulation of the effective compression ratio, a measure of the amount of compression of in-cylinder gases above Intake manifold conditions, is a key enabler of advanced combustion strategies aimed at reducing emissions while maintaining efficiency, and is directly influenced by modulation of Intake Valve closing time. To date, the effective compression ratio has most commonly been calculated from in-cylinder pressure data, requiring reliable in-cylinder pressure sensors. These sensors are generally not found on production engines, and thus a method is needed to determine effective compression ratio without in-cylinder pressure data. The work presented here outlines an estimation scheme that combines a high-gain observer with a physically-based volumetric efficiency model to estimate effective compression ratio using only information available from stock engine sensors, including manifold pressures and temperatures and air flows. The estimation scheme is compared to experimental engine data from a unique ...
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Effect of Intake Valve closure modulation on effective compression ratio and gas exchange in turbocharged multi-cylinder engines utilizing EGR
International Journal of Engine Research, 2011Co-Authors: R Modiyani, Lyle Kocher, Ed Koeberlein, D. G. Van Alstine, Karla Stricker, P.h. Meckl, Gregory M. ShaverAbstract:Advanced combustion strategies including premixed charge compression ignition, homogeneous charge compression ignition, and lifted flame combustion are promising approaches for meeting increasingly stringent emissions regulations and improving fuel efficiency in next generation powertrains. Variable Valve actuation and closed-loop control promise to play a key role in the promotion and control of these advanced combustion modes. For example, modulation of Intake Valve closure timing dictates the effective compression ratio and influences the total amount of charge trapped inside the cylinder, and in so doing allows manipulation of the in-cylinder reactant concentrations and temperature prior to and during the combustion process. The effort described here uses data from, and an experimentally-validated simulation model for, a multi-cylinder engine with variable geometry turbocharging, cooled exhaust gas recirculation, and fully flexible variable Valve actuation. This effort’s intent is to determine the con...
Ed Koeberlein - One of the best experts on this subject based on the ideXlab platform.
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Oxygen fraction estimation for diesel engines utilizing variable Intake Valve actuation
2012 American Control Conference (ACC), 2012Co-Authors: Lyle E. Kocher, D. G. Van Alstine, Ed Koeberlein, Karla Stricker, Gregory M. ShaverAbstract:Advanced diesel engine architectures employing flexible Valve trains enable emissions reductions and fuel economy improvements through advanced combustion strategies. These combustion strategies, such as pre-mixed charge compression ignition (PCCI), homogenous charge compression ignition (HCCI) and low temperature combustion (LTC), are controlled and enabled through the use of flexible Valve trains. The in-cylinder oxygen concentration serves as a critical input in controlling these strategies. Unfortunately, the in-cylinder oxygen concentration is extremely difficult to measure on production engines. However, the oxygen concentrations in the Intake and exhaust manifold can be utilized to calculate the in-cylinder oxygen concentration when the charge and residual in-cylinder mass are available. A model-based observer is developed to estimate the oxygen concentration in the Intake and exhaust manifolds. The oxygen concentration estimates will be sensitive to errors in the mass flows of the manifold filling dynamics. To improve the EGR flow measurement, a high-gain observer is implemented to provide a more accurate EGR flow estimate. The observer estimates the oxygen concentrations to within 0.5% O2 and converges in less than 0.5 seconds.
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Effective compression ratio estimation in engines with flexible Intake Valve actuation
2012 American Control Conference (ACC), 2012Co-Authors: Karla Stricker, Lyle Kocher, Ed Koeberlein, D. G. Van Alstine, Gregory M. ShaverAbstract:The ability to modulate the effective compression ratio (ECR) of an engine is a key enabler of advanced combustion strategies. ECR is a measure of the effective in-cylinder compression of gases above Intake manifold conditions. An engine's ECR is usually computed from in-cylinder pressure data, requiring reliable in-cylinder pressure sensors that are not typically found on production engines. As such, a method is needed for determining the effective compression ratio using only information available from stock engine sensors, including manifold pressures and temperatures and air flows. The work outlined here presents a strategy for estimating the ECR without need for in-cylinder pressure data. The estimation scheme was transiently tested and compared to experimental engine data from a unique diesel engine test bed with flexible Intake Valve actuation, and was able to converge within 3 engine cycles after a transient event with less than 6% average steady-state error compared to experimental engine data.
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physically based volumetric efficiency model for diesel engines utilizing variable Intake Valve actuation
International Journal of Engine Research, 2012Co-Authors: Lyle Kocher, Ed Koeberlein, D. G. Van Alstine, Karla Stricker, Gregory M. ShaverAbstract:Advanced diesel engine architectures employing flexible Valve trains enable emissions reductions and fuel economy improvements. Flexibility in the Valve train allows engine designers to optimize th...
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Estimation of effective compression ratio for engines utilizing flexible Intake Valve actuation
Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 2012Co-Authors: Karla Stricker, Lyle Kocher, Ed Koeberlein, D. G. Van Alstine, Gregory M. ShaverAbstract:Modulation of the effective compression ratio, a measure of the amount of compression of in-cylinder gases above Intake manifold conditions, is a key enabler of advanced combustion strategies aimed at reducing emissions while maintaining efficiency, and is directly influenced by modulation of Intake Valve closing time. To date, the effective compression ratio has most commonly been calculated from in-cylinder pressure data, requiring reliable in-cylinder pressure sensors. These sensors are generally not found on production engines, and thus a method is needed to determine effective compression ratio without in-cylinder pressure data. The work presented here outlines an estimation scheme that combines a high-gain observer with a physically-based volumetric efficiency model to estimate effective compression ratio using only information available from stock engine sensors, including manifold pressures and temperatures and air flows. The estimation scheme is compared to experimental engine data from a unique ...
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Effect of Intake Valve closure modulation on effective compression ratio and gas exchange in turbocharged multi-cylinder engines utilizing EGR
International Journal of Engine Research, 2011Co-Authors: R Modiyani, Lyle Kocher, Ed Koeberlein, D. G. Van Alstine, Karla Stricker, P.h. Meckl, Gregory M. ShaverAbstract:Advanced combustion strategies including premixed charge compression ignition, homogeneous charge compression ignition, and lifted flame combustion are promising approaches for meeting increasingly stringent emissions regulations and improving fuel efficiency in next generation powertrains. Variable Valve actuation and closed-loop control promise to play a key role in the promotion and control of these advanced combustion modes. For example, modulation of Intake Valve closure timing dictates the effective compression ratio and influences the total amount of charge trapped inside the cylinder, and in so doing allows manipulation of the in-cylinder reactant concentrations and temperature prior to and during the combustion process. The effort described here uses data from, and an experimentally-validated simulation model for, a multi-cylinder engine with variable geometry turbocharging, cooled exhaust gas recirculation, and fully flexible variable Valve actuation. This effort’s intent is to determine the con...
Tianyou Wang - One of the best experts on this subject based on the ideXlab platform.
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the potential of high load extension by using late Intake Valve closing for a diesel premixed charge compression ignition pcci engine
Energy Procedia, 2015Co-Authors: Ming Jia, Hu Wang, Tianyou Wang, Maozhao Xie, Rolf D ReitzAbstract:Abstract Premixed charge compression ignition (PCCI) combustion is capable of reducing nitrogen oxides (NO x ) and soot emissions simultaneously, while remaining high fuel efficiency. Whereas, PCCI combustion still faces the challenges of the control of ignition timing and the expansion of operating range. In this study, by coupling a multi-dimensional computational fluid dynamics (CFD) code and genetic algorithm (GA), the potential of high-load expansion by using late Intake Valve closing (IVC) was explored in a light-duty diesel PCCI engine. It was revealed that low fuel consumption, and low NO x and soot emissions could be achieved with the employment of retarded IVC timing, high EGR rate, boosted Intake pressure, and optimized injection timing.
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numerical investigation of the influence of Intake Valve lift profile on a diesel premixed charge compression ignition engine with a variable Valve actuation system at moderate loads and speeds
International Journal of Engine Research, 2013Co-Authors: Tianyou WangAbstract:Variable Valve actuation is attracting increasing attention for the control of diesel premixed charge compression ignition engines due to its fast-response characteristics. In this study, a three-dimensional computational fluid dynamics model, coupled with detailed chemical kinetics, is used to evaluate the influence of the Intake Valve lift profile on combustion and emissions of a diesel premixed charge compression ignition engine at moderate loads and speeds. The results indicate that, among all the tested variable Valve actuation strategies, late Intake Valve closing shows the most potential for control of ignition timing and reduction of nitrogen oxide emissions, while maintaining low soot emissions and fuel consumption. A moderate decrease of Intake Valve lift is beneficial for the reduction of soot emissions without significant impacts on fuel consumption due to the enhanced Intake flow. The enhancement of turbulence kinetic energy of the in-cylinder mixture is helpful for fuel/air mixing and soot r...
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Numerical evaluation of the potential of late Intake Valve closing strategy for diesel PCCI (premixed charge compression ignition) engine in a wide speed and load range
Energy, 2013Co-Authors: Ming Jia, Maozhao Xie, Tianyou WangAbstract:A full-engine-cycle multidimensional model was applied to investigate the effect of late (Intake Valve closing) IVC on combustion and emission characteristics in a diesel (premixed charge compression ignition) PCCI engine in a wide speed and load range. The results indicate that the in-cylinder swirl ratio and turbulence kinetic energy are significantly enhanced with increased engine speed, while only swirl ratio is slightly affected by the variation in IVC timing. In PCCI combustion mode, ignition timing varies with engine load and speed, and late IVC strategy leads to a noticeable delay in ignition timing by decreasing the effective compression ratio over all the operating range. Late IVC is a very effective approach for reduction of (nitrogen oxides) NOx emissions in the whole operating range, but the benefit of soot reduction with late IVC only locates in the low-to-medium load range. Moreover, it is found that indicated specific fuel consumption is effectively decreased with the employment of late IVC strategy in the medium-to-high load and low-to-medium speed range. Overall, by delaying ignition phasing and decreasing combustion temperature from late IVC timing, the high NOx emissions at medium load, and low fuel efficiency at low speed can be avoided for PCCI combustion.
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the effect of injection timing and Intake Valve close timing on performance and emissions of diesel pcci engine with a full engine cycle cfd simulation
Applied Energy, 2011Co-Authors: Ming Jia, Tianyou Wang, Maozhao Xie, Zhijun PengAbstract:Abstract A full-cycle computational fluid dynamics (CFD) simulation coupled with detailed chemical kinetics mechanism has been used to investigate the effect of start of injection (SOI) timing and Intake Valve close (IVC) timing on performance and emissions of diesel premixed charge compression ignition (PCCI) engine. By sweeping SOI timing from −35 to −5 °CA ATDC and IVC timing from −140 to −80 °CA ATDC with fixed 50% exhaust gas recirculation (EGR) and 1.8 bar Intake pressure, the contour plots for ignition timing, nitric oxides (NO x ), soot, hydrocarbon (HC), carbon monoxide (CO), indicated specific fuel consumption (ISFC), and ringing intensity have been developed. The results indicate that the operating range can be divided into kinetically controlled region and mixing-controlled region, in which the ignition timing is solely controlled by IVC timing and SOI timing respectively. To Minimize HC, CO, NO x and soot emissions, SOI timing must be carefully adjusted within a limited range. With the retarded IVC timing, the operating range of SOI becomes wider for clean combustion. The IVC timing should be optimized with consideration of ignition timing and combustion efficiency at different SOI timing in order to improve fuel economy. For purpose of avoiding engine knock, the SOI timing around −20 °CA ATDC and early IVC timing are pursued.