A frequency compensation control method for the opposed-piston two-stroke folded-cranktrain（ OPFC） diesel engine＇s common rail system is presented as a result of the study of the loop-shaping theory. A common rail ...A frequency compensation control method for the opposed-piston two-stroke folded-cranktrain（ OPFC） diesel engine＇s common rail system is presented as a result of the study of the loop-shaping theory. A common rail working process and the classical frequency control theory are combined to construct a frequency restriction of common rail pressure. A frequency compensator is utilized to improve the robustness of multiplicative perturbations and disturbance. The loop-shaping method has been applied to design the common rail pressure controller of the OPFC diesel engine. Simulation and bench test results show that in the condition of perturbation that comes from the effect of injection,multi-injection,fuel pumping of a pre-cylinder,and instantaneous pressure fluctuation,the controller indicates high precision. Compared with the original controller,this method improves the control precision by 67. 3%.展开更多
The global demand for transport energy is large, growing, and primarily met by petroleum-derived liquid fuels powering internal combustion engines (ICEs). Moreover, the demand for jet fuel and diesel is projected to g...The global demand for transport energy is large, growing, and primarily met by petroleum-derived liquid fuels powering internal combustion engines (ICEs). Moreover, the demand for jet fuel and diesel is projected to grow faster than the demand for gasoline in the future, and is likely to result in low-octane gasoline components becoming more readily available. Significant initiatives with varying motivations are taking place to develop the battery electric vehicle (BEV) and the fuel cell as alternatives to ICE vehicles, and to establish fuels such as biofuels and natural gas as alternatives to conventional liquid fuels. However, each of these alternatives starts from a very low base and faces significant barriers to fast and unrestrained growth;thus, transport—and particularly commercial transport—will continue to be largely powered by ICEs running on petroleum-based liquid fuels for decades to come. Hence, the sustainability of transport in terms of affordability, energy security, and impact on greenhouse gas (GHG) emissions and air quality can only be ensured by improving ICEs. Indeed, ICEs will continue to improve while using current market fuels, through improvements in combustion, control, and after-treatment systems, assisted by partial electrification in the form of hybridization. However, there is even more scope for improvement through the development of fuel/engine systems that can additionally leverage benefits in fuels manufacture and use components that may be readily available. Gasoline compression ignition (GCI), which uses low-octane gasoline in a compression ignition engine, is one such example. GCI would enable diesel-like efficiencies while making it easier to control nitrogen oxides (NOx) and particulates at a lower cost compared with modern diesel engines. Octane on demand (OOD) also helps to ensure optimum use of available fuel anti-knock quality, and thus improves the overall efficiency of the system.展开更多
We studied engine-out soot samples collected from a heavy-duty direct-injection diesel engine and port-fuel injection gasoline spark-ignition engine. The two types of soot samples were characterized using Raman spectr...We studied engine-out soot samples collected from a heavy-duty direct-injection diesel engine and port-fuel injection gasoline spark-ignition engine. The two types of soot samples were characterized using Raman spectroscopy with different laser powers. A Matlab program using least-square-method with trust-region-reflective algorithm was developed for curve fitting. A DOE(design of experiments) method was used to avoid local convergence. The method was used for two-band fitting and three-band fitting. The fitting results were used to determine the intensity ratio of D(for "Defect" or "Disorder") and G(for"Graphite") Raman bands. It is found that high laser power may cause oxidation of soot sample, which gives higher D/G intensity ratio. Diesel soot has consistently higher amorphous/graphitic carbon ratio, and thus higher oxidation reactivity, compared to gasoline soot, which is reflected by the higher D/G intensity ratio in Raman spectra measured under the same laser power.展开更多
In the present study, the performance of a 4-stroke diesel engine was experimentally evaluated upon adding Al2O3 or SiO2 nanoparticles to the engine oil （SAEISW40）. The viscosity and density of the resulting nanolub...In the present study, the performance of a 4-stroke diesel engine was experimentally evaluated upon adding Al2O3 or SiO2 nanoparticles to the engine oil （SAEISW40）. The viscosity and density of the resulting nanolubricants were determined while varying both the nanoparticle volume fraction and the temperature. Field emission scanning electron microscopy （FE-SEM） showed that the nanoparticles had a spherical morphology and dynamic light scattering analysis determined some aggregation of the nanoparticles in the engine oil. A pin-on-disc test apparatus was used for friction and wear analysis in the presence of the nanolubricants. Examination of wear scars by FE-SEM and energy dispersive spectroscopy found evidence of ball bearing and surface polishing effects, which were responsible for improvements in the tribological properties of the oil. The performance of these nanolubricants in a 4- stroke diesel engine test rig was assessed, and the greatest improvements in the tribological behavior and engine performance were observed when employing 0.3 vol% Al2O3.展开更多
基金Supported by the National Natural Science Foundation of China(51406013)
文摘A frequency compensation control method for the opposed-piston two-stroke folded-cranktrain（ OPFC） diesel engine＇s common rail system is presented as a result of the study of the loop-shaping theory. A common rail working process and the classical frequency control theory are combined to construct a frequency restriction of common rail pressure. A frequency compensator is utilized to improve the robustness of multiplicative perturbations and disturbance. The loop-shaping method has been applied to design the common rail pressure controller of the OPFC diesel engine. Simulation and bench test results show that in the condition of perturbation that comes from the effect of injection,multi-injection,fuel pumping of a pre-cylinder,and instantaneous pressure fluctuation,the controller indicates high precision. Compared with the original controller,this method improves the control precision by 67. 3%.
文摘The global demand for transport energy is large, growing, and primarily met by petroleum-derived liquid fuels powering internal combustion engines (ICEs). Moreover, the demand for jet fuel and diesel is projected to grow faster than the demand for gasoline in the future, and is likely to result in low-octane gasoline components becoming more readily available. Significant initiatives with varying motivations are taking place to develop the battery electric vehicle (BEV) and the fuel cell as alternatives to ICE vehicles, and to establish fuels such as biofuels and natural gas as alternatives to conventional liquid fuels. However, each of these alternatives starts from a very low base and faces significant barriers to fast and unrestrained growth;thus, transport—and particularly commercial transport—will continue to be largely powered by ICEs running on petroleum-based liquid fuels for decades to come. Hence, the sustainability of transport in terms of affordability, energy security, and impact on greenhouse gas (GHG) emissions and air quality can only be ensured by improving ICEs. Indeed, ICEs will continue to improve while using current market fuels, through improvements in combustion, control, and after-treatment systems, assisted by partial electrification in the form of hybridization. However, there is even more scope for improvement through the development of fuel/engine systems that can additionally leverage benefits in fuels manufacture and use components that may be readily available. Gasoline compression ignition (GCI), which uses low-octane gasoline in a compression ignition engine, is one such example. GCI would enable diesel-like efficiencies while making it easier to control nitrogen oxides (NOx) and particulates at a lower cost compared with modern diesel engines. Octane on demand (OOD) also helps to ensure optimum use of available fuel anti-knock quality, and thus improves the overall efficiency of the system.
文摘We studied engine-out soot samples collected from a heavy-duty direct-injection diesel engine and port-fuel injection gasoline spark-ignition engine. The two types of soot samples were characterized using Raman spectroscopy with different laser powers. A Matlab program using least-square-method with trust-region-reflective algorithm was developed for curve fitting. A DOE(design of experiments) method was used to avoid local convergence. The method was used for two-band fitting and three-band fitting. The fitting results were used to determine the intensity ratio of D(for "Defect" or "Disorder") and G(for"Graphite") Raman bands. It is found that high laser power may cause oxidation of soot sample, which gives higher D/G intensity ratio. Diesel soot has consistently higher amorphous/graphitic carbon ratio, and thus higher oxidation reactivity, compared to gasoline soot, which is reflected by the higher D/G intensity ratio in Raman spectra measured under the same laser power.
文摘In the present study, the performance of a 4-stroke diesel engine was experimentally evaluated upon adding Al2O3 or SiO2 nanoparticles to the engine oil （SAEISW40）. The viscosity and density of the resulting nanolubricants were determined while varying both the nanoparticle volume fraction and the temperature. Field emission scanning electron microscopy （FE-SEM） showed that the nanoparticles had a spherical morphology and dynamic light scattering analysis determined some aggregation of the nanoparticles in the engine oil. A pin-on-disc test apparatus was used for friction and wear analysis in the presence of the nanolubricants. Examination of wear scars by FE-SEM and energy dispersive spectroscopy found evidence of ball bearing and surface polishing effects, which were responsible for improvements in the tribological properties of the oil. The performance of these nanolubricants in a 4- stroke diesel engine test rig was assessed, and the greatest improvements in the tribological behavior and engine performance were observed when employing 0.3 vol% Al2O3.
