The Experts below are selected from a list of 810 Experts worldwide ranked by ideXlab platform
Ming Jia - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation of cyclic variability in reactivity controlled compression ignition combustion with a focus on the initial temperature at Intake Valve Closing
International Journal of Engine Research, 2015Co-Authors: Ming Jia, Hu Wang, Adam B Dempsey, Rolf D ReitzAbstract:Cyclic variations in dual-fuel reactivity-controlled compression ignition combustion were investigated using multi-dimensional simulations of a light-duty diesel engine. By comparing results with m...
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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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parametric study and optimization of a rcci reactivity controlled compression ignition engine fueled with methanol and diesel
Energy, 2014Co-Authors: Ming Jia, Tianyou Wang, Maozhao Xie, Yachao Chang, Yaodong Liu, Lei ZhouAbstract:By integrating an updated multi-dimensional model and the NSGA-II (non-dominated sorting genetic algorithm II), the combustion of a RCCI (reactivity controlled compression ignition) engine fueled with methanol/diesel was optimized. Based on the optimization results, parametric study was performed by varying energy fraction of methanol, EGR (exhaust gas recirculation rate, initial in-cylinder pressure at IVC (Intake Valve Closing), initial in-cylinder temperature at IVC, and SOI (start of injection). Furthermore, the sensitivities of these five parameters on fuel efficiency, emissions, ignition timing and RI (ringing intensity) were analyzed. The results indicated that initial temperature and EGR rate exhibited the most significant effect on engine performance and emissions for their obvious effect on combustion temperature. By varying the local fuel-rich and high-temperature regions, methanol fraction and SOI could dramatically affect NOx (nitrogen oxide) emission. Overall, the RCCI combustion with high methanol fraction and advanced SOI exhibited higher fuel efficiency and lower emissions. Moreover, it was found that both decreasing EGR rate and increasing initial temperature led to the monotonously increased RI. While decreasing methanol fraction and increasing initial pressure demonstrated the negligible effect on RI at CA50 earlier than 4.3 °CA ATDC, which was contributed to their obvious effect on fuel spatial distributions.
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numerical study on the combustion and emission characteristics of a methanol diesel reactivity controlled compression ignition rcci engine
Applied Energy, 2013Co-Authors: Ming Jia, Yaodong Liu, Maozhao XieAbstract:Abstract An improved multi-dimensional model coupled with detailed chemical kinetics mechanism was applied to investigate the combustion and emission characteristics of a methanol/diesel reactivity controlled compression ignition (RCCI) engine. The fuel was supplied separately by directly injecting diesel fuel into cylinder well before top dead center, while premixing methanol through the Intake port in the tested methanol/diesel RCCI engine. The effects of mass fraction of premixed methanol, start of injection (SOI) of diesel and initial in-cylinder temperature at Intake Valve Closing (IVC) on engine combustion and emission were investigated in detail. The results show that both methanol mass fraction and SOI have a significant impact on cetane number (CN) distribution, i.e. fuel reactivity distribution, which determines the ignition delay and peak of heat release rate (HRR). Due to larger area with high-temperature region and more homogeneous fuel distribution with increased methanol, and the oxygen atom contained by methanol molecule, all the emissions are reduced with moderate methanol addition. Advanced SOI with high combustion temperature is favorable to hydrocarbon (HC) and soot reduction, yet not to the decrease of nitrogen oxide (NOx) and carbon monoxide (CO) emissions. Both increasing methanol fraction and advancing the SOI are beneficial to improve fuel economy and avoid engine knock. Moreover, it was revealed that the initial temperature must be increased with increased methanol fraction to keep the 50% burn point (CA50) constant, which results in decrease of the equivalent indicated specific fuel consumption (EISFC) and all emissions, except for slight increase in NOx due to the higher burning temperature.
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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.
Maozhao Xie - 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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parametric study and optimization of a rcci reactivity controlled compression ignition engine fueled with methanol and diesel
Energy, 2014Co-Authors: Ming Jia, Tianyou Wang, Maozhao Xie, Yachao Chang, Yaodong Liu, Lei ZhouAbstract:By integrating an updated multi-dimensional model and the NSGA-II (non-dominated sorting genetic algorithm II), the combustion of a RCCI (reactivity controlled compression ignition) engine fueled with methanol/diesel was optimized. Based on the optimization results, parametric study was performed by varying energy fraction of methanol, EGR (exhaust gas recirculation rate, initial in-cylinder pressure at IVC (Intake Valve Closing), initial in-cylinder temperature at IVC, and SOI (start of injection). Furthermore, the sensitivities of these five parameters on fuel efficiency, emissions, ignition timing and RI (ringing intensity) were analyzed. The results indicated that initial temperature and EGR rate exhibited the most significant effect on engine performance and emissions for their obvious effect on combustion temperature. By varying the local fuel-rich and high-temperature regions, methanol fraction and SOI could dramatically affect NOx (nitrogen oxide) emission. Overall, the RCCI combustion with high methanol fraction and advanced SOI exhibited higher fuel efficiency and lower emissions. Moreover, it was found that both decreasing EGR rate and increasing initial temperature led to the monotonously increased RI. While decreasing methanol fraction and increasing initial pressure demonstrated the negligible effect on RI at CA50 earlier than 4.3 °CA ATDC, which was contributed to their obvious effect on fuel spatial distributions.
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numerical study on the combustion and emission characteristics of a methanol diesel reactivity controlled compression ignition rcci engine
Applied Energy, 2013Co-Authors: Ming Jia, Yaodong Liu, Maozhao XieAbstract:Abstract An improved multi-dimensional model coupled with detailed chemical kinetics mechanism was applied to investigate the combustion and emission characteristics of a methanol/diesel reactivity controlled compression ignition (RCCI) engine. The fuel was supplied separately by directly injecting diesel fuel into cylinder well before top dead center, while premixing methanol through the Intake port in the tested methanol/diesel RCCI engine. The effects of mass fraction of premixed methanol, start of injection (SOI) of diesel and initial in-cylinder temperature at Intake Valve Closing (IVC) on engine combustion and emission were investigated in detail. The results show that both methanol mass fraction and SOI have a significant impact on cetane number (CN) distribution, i.e. fuel reactivity distribution, which determines the ignition delay and peak of heat release rate (HRR). Due to larger area with high-temperature region and more homogeneous fuel distribution with increased methanol, and the oxygen atom contained by methanol molecule, all the emissions are reduced with moderate methanol addition. Advanced SOI with high combustion temperature is favorable to hydrocarbon (HC) and soot reduction, yet not to the decrease of nitrogen oxide (NOx) and carbon monoxide (CO) emissions. Both increasing methanol fraction and advancing the SOI are beneficial to improve fuel economy and avoid engine knock. Moreover, it was revealed that the initial temperature must be increased with increased methanol fraction to keep the 50% burn point (CA50) constant, which results in decrease of the equivalent indicated specific fuel consumption (EISFC) and all emissions, except for slight increase in NOx due to the higher burning temperature.
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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.
Rolf D Reitz - One of the best experts on this subject based on the ideXlab platform.
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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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numerical simulation of cyclic variability in reactivity controlled compression ignition combustion with a focus on the initial temperature at Intake Valve Closing
International Journal of Engine Research, 2015Co-Authors: Ming Jia, Hu Wang, Adam B Dempsey, Rolf D ReitzAbstract:Cyclic variations in dual-fuel reactivity-controlled compression ignition combustion were investigated using multi-dimensional simulations of a light-duty diesel engine. By comparing results with m...
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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.
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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parametric study and optimization of a rcci reactivity controlled compression ignition engine fueled with methanol and diesel
Energy, 2014Co-Authors: Yaopeng Li, Tianyou Wang, Yachao Chang, Lei ZhouAbstract:By integrating an updated multi-dimensional model and the NSGA-II (non-dominated sorting genetic algorithm II), the combustion of a RCCI (reactivity controlled compression ignition) engine fueled with methanol/diesel was optimized. Based on the optimization results, parametric study was performed by varying energy fraction of methanol, EGR (exhaust gas recirculation rate, initial in-cylinder pressure at IVC (Intake Valve Closing), initial in-cylinder temperature at IVC, and SOI (start of injection). Furthermore, the sensitivities of these five parameters on fuel efficiency, emissions, ignition timing and RI (ringing intensity) were analyzed. The results indicated that initial temperature and EGR rate exhibited the most significant effect on engine performance and emissions for their obvious effect on combustion temperature. By varying the local fuel-rich and high-temperature regions, methanol fraction and SOI could dramatically affect NOx (nitrogen oxide) emission. Overall, the RCCI combustion with high methanol fraction and advanced SOI exhibited higher fuel efficiency and lower emissions. Moreover, it was found that both decreasing EGR rate and increasing initial temperature led to the monotonously increased RI. While decreasing methanol fraction and increasing initial pressure demonstrated the negligible effect on RI at CA50 earlier than 4.3 °CA ATDC, which was contributed to their obvious effect on fuel spatial distributions.
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parametric study and optimization of a rcci reactivity controlled compression ignition engine fueled with methanol and diesel
Energy, 2014Co-Authors: Ming Jia, Tianyou Wang, Maozhao Xie, Yachao Chang, Yaodong Liu, Lei ZhouAbstract:By integrating an updated multi-dimensional model and the NSGA-II (non-dominated sorting genetic algorithm II), the combustion of a RCCI (reactivity controlled compression ignition) engine fueled with methanol/diesel was optimized. Based on the optimization results, parametric study was performed by varying energy fraction of methanol, EGR (exhaust gas recirculation rate, initial in-cylinder pressure at IVC (Intake Valve Closing), initial in-cylinder temperature at IVC, and SOI (start of injection). Furthermore, the sensitivities of these five parameters on fuel efficiency, emissions, ignition timing and RI (ringing intensity) were analyzed. The results indicated that initial temperature and EGR rate exhibited the most significant effect on engine performance and emissions for their obvious effect on combustion temperature. By varying the local fuel-rich and high-temperature regions, methanol fraction and SOI could dramatically affect NOx (nitrogen oxide) emission. Overall, the RCCI combustion with high methanol fraction and advanced SOI exhibited higher fuel efficiency and lower emissions. Moreover, it was found that both decreasing EGR rate and increasing initial temperature led to the monotonously increased RI. While decreasing methanol fraction and increasing initial pressure demonstrated the negligible effect on RI at CA50 earlier than 4.3 °CA ATDC, which was contributed to their obvious effect on fuel spatial distributions.
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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.
Yaopeng Li - One of the best experts on this subject based on the ideXlab platform.
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parametric study and optimization of a rcci reactivity controlled compression ignition engine fueled with methanol and diesel
Energy, 2014Co-Authors: Yaopeng Li, Tianyou Wang, Yachao Chang, Lei ZhouAbstract:By integrating an updated multi-dimensional model and the NSGA-II (non-dominated sorting genetic algorithm II), the combustion of a RCCI (reactivity controlled compression ignition) engine fueled with methanol/diesel was optimized. Based on the optimization results, parametric study was performed by varying energy fraction of methanol, EGR (exhaust gas recirculation rate, initial in-cylinder pressure at IVC (Intake Valve Closing), initial in-cylinder temperature at IVC, and SOI (start of injection). Furthermore, the sensitivities of these five parameters on fuel efficiency, emissions, ignition timing and RI (ringing intensity) were analyzed. The results indicated that initial temperature and EGR rate exhibited the most significant effect on engine performance and emissions for their obvious effect on combustion temperature. By varying the local fuel-rich and high-temperature regions, methanol fraction and SOI could dramatically affect NOx (nitrogen oxide) emission. Overall, the RCCI combustion with high methanol fraction and advanced SOI exhibited higher fuel efficiency and lower emissions. Moreover, it was found that both decreasing EGR rate and increasing initial temperature led to the monotonously increased RI. While decreasing methanol fraction and increasing initial pressure demonstrated the negligible effect on RI at CA50 earlier than 4.3 °CA ATDC, which was contributed to their obvious effect on fuel spatial distributions.
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numerical study on the combustion and emission characteristics of a methanol diesel reactivity controlled compression ignition rcci engine
Applied Energy, 2013Co-Authors: Yaopeng LiAbstract:An improved multi-dimensional model coupled with detailed chemical kinetics mechanism was applied to investigate the combustion and emission characteristics of a methanol/diesel reactivity controlled compression ignition (RCCI) engine. The fuel was supplied separately by directly injecting diesel fuel into cylinder well before top dead center, while premixing methanol through the Intake port in the tested methanol/diesel RCCI engine. The effects of mass fraction of premixed methanol, start of injection (SOI) of diesel and initial in-cylinder temperature at Intake Valve Closing (IVC) on engine combustion and emission were investigated in detail. The results show that both methanol mass fraction and SOI have a significant impact on cetane number (CN) distribution, i.e. fuel reactivity distribution, which determines the ignition delay and peak of heat release rate (HRR). Due to larger area with high-temperature region and more homogeneous fuel distribution with increased methanol, and the oxygen atom contained by methanol molecule, all the emissions are reduced with moderate methanol addition. Advanced SOI with high combustion temperature is favorable to hydrocarbon (HC) and soot reduction, yet not to the decrease of nitrogen oxide (NOx) and carbon monoxide (CO) emissions. Both increasing methanol fraction and advancing the SOI are beneficial to improve fuel economy and avoid engine knock. Moreover, it was revealed that the initial temperature must be increased with increased methanol fraction to keep the 50% burn point (CA50) constant, which results in decrease of the equivalent indicated specific fuel consumption (EISFC) and all emissions, except for slight increase in NOx due to the higher burning temperature.