The fuel dynamic transfer process,including fuel injection,fuel film deposition and evaporation in the intake port,was analyzed for spark ignition(SI) engines with port fuel injection(PFI).The influence of wall-wettin...The fuel dynamic transfer process,including fuel injection,fuel film deposition and evaporation in the intake port,was analyzed for spark ignition(SI) engines with port fuel injection(PFI).The influence of wall-wetting fuel film,especially its evaporation rate,upon the air-fuel ratio of in-cylinder mixtures was also discussed.According to the similarity principle,Fick's law,the ideal gas equation and the Gilliland correlation,an evaporate prediction model of wall-wetting fuel film was set up and an evaporate prediction based dynamic fuel film compensator was designed.Through engine cold start tests,the wall-wetting temperature,which is the key input of the fuel film evaporate prediction model,was also modeled and predicted.Combined with the experimental data of the evaporation characteristics of ethanol-gasoline blends and engine calibration tests,all the parameters of the wall-wetting fuel film evaporate prediction model used in the fuel film compensator were identified.Square-wave disturbance tests of fuel injection showed that with the help of the fuel film compensator the response of the in-cylinder air-fuel ratio was significantly improved and the real air-fuel ratio always closely matched the expected ratio.The fuel film compensator was then integrated into the final air-fuel ratio controller,and the engine tests showed that the air-fuel ratio control error was less than 2% in steady-state conditions,and less than 4% in transient conditions.The fuel film compensator also showed good adaptability to different ethanol-gasoline blends.展开更多
One of the proposed concepts for spark ignition engines is advanced port fuel injection(APFI),which suggests using two port injectors for each cylinder.In this research,we numerically examine the capabilities of this ...One of the proposed concepts for spark ignition engines is advanced port fuel injection(APFI),which suggests using two port injectors for each cylinder.In this research,we numerically examine the capabilities of this concept in reducing fuel consumption and increasing engine performance.The results demonstrated that the use of this concept is very effective due to the use of two injectors and the possibility of reducing the spraying time and bringing the injection start time closer to the air inlet valve opening time.The maximum amount of fuel film formed on the walls is reduced by about 75%,naturally,which leads to better and more homogeneous fuel distribution inside the combustion chamber and increases combustion efficiency.The results showed that under the same boundary conditions and engine operating point,the use of two port injectors for each cylinder leads to an increase of more than 20%of the maximum combustion chamber pressure and about 4%combustion efficiency.On the other hand,fuel film formation becomes worse in cold conditions.So in this study,the capabilities of this concept in cold conditions were investigated too.Investigations have shown that the advanced port fuel injection,unlike conventional engines,is almost insensitive to inlet temperature changes.展开更多
Polyalkylmethacrylates(PAMAs) are well-known as viscosity index improvers and dispersant boosters.This paper shows that PAMAs are able to adsorb from oil solution on to metal surfaces,to produce thick,viscous boundary...Polyalkylmethacrylates(PAMAs) are well-known as viscosity index improvers and dispersant boosters.This paper shows that PAMAs are able to adsorb from oil solution on to metal surfaces,to produce thick,viscous boundary films.These films enhance lubricant film formation in slow speed and high temperature conditions and thus produce a significant reduction of friction.A systematic study of this phenomenon has made use of the highly flexible nature of PAMA chemistry.A range of dispersant and non-dispersant polymethacrylates has been synthesized.The influence of different functionalities,molecular weights and architectures on both boundary film formation and friction has been explored using optical interferometry and friction-speed charting.From the results, guidelines have been developed for designing PAMAs having optimal boundary lubricating properties.Through their ability to form boundary films PAMAs can significantly contribute to reduce wear in engine,gear and hydraulic lubrication.As a consequence of their viscometric and tribological performance PAMAs can furthermore improve fuel and energy efficiency in different,namely engine and hydraulic applications.Extensive work is currently conducted in the lubricant industry to develop engine oils with lower sulfur,phosphorus and metal content(low SAPS) and to optimize their frictional properties through the use of friction modifiers or synthetic base stocks.We have investigated the contribution of PAMA viscosity index improvers and boosters to improve fuel economy and to reduce wear levels.This paper reports our efforts to develop a new range of PAMAs that have been optimized in terms of composition,architecture,molecular weight and functionality and which can be used in low viscosity,low SAPS formulations to help meet the stringent requirements of modern engine oils.展开更多
Sm and Gd co-doped Ceria (SGDC:Sm_(0.1)Gd_(0.1)Ce_(0.8)O_(1.90)) films as the electrolytes were investigated for the IT-SOFCs (intermediate-temperature solid oxide fuel cells).SGDC sensing films were successfully prep...Sm and Gd co-doped Ceria (SGDC:Sm_(0.1)Gd_(0.1)Ce_(0.8)O_(1.90)) films as the electrolytes were investigated for the IT-SOFCs (intermediate-temperature solid oxide fuel cells).SGDC sensing films were successfully prepared on the Al_2O_3 substrates by RF-magnetron sputtering.The relationship between sputtering parameters and film microstructure was discussed, and the optimum parameters were gained.The crystal structure analysis and surface morphologic observation of the SGDC films were carried out through X-ray diffraction (XRD) and scanning electron microscopy (SEM).The oxygen ion conductivity of the SGDC film was evaluated by AC impedance spectroscopy at the different temperatures.The XRD analysis shows that the SGDC films grow preferentially along the (111) compact plane.The crystallinity of the SGDC films is enhanced with the increase of the RF sputtering power from 150 W to 250 W.The oxygen ion conductivity of the SGDC was measured at the temperature from 600℃to 800℃in air by AC impedance spectroscopy.The result shows that a high oxygen ion conductivity of 2.44×10^(-2) S.cm^(-1) was achieved at 800℃.展开更多
A 65. 8-μm dense doped lanthanum gallate La0.8Sr0.2 Ga0.85 Mg0.15 O2.825（LSGM）film was prepared on a porous Ni/SDC（samarium doped ceria, Ce0.8Sm0.2O1.9 ） anode support by colloid susponsion deposition with incomp...A 65. 8-μm dense doped lanthanum gallate La0.8Sr0.2 Ga0.85 Mg0.15 O2.825（LSGM）film was prepared on a porous Ni/SDC（samarium doped ceria, Ce0.8Sm0.2O1.9 ） anode support by colloid susponsion deposition with incomplete crystallization LSGM powder as a starting material. The phase composition and micromorphology of the LSGM film were characterized by X-ray diffraction and scanning electron microscopy. The electrical properties of the LSGM film and the performances of the LSGM film solid oxide fuel cell were also analyzed. The results show that beth the dense LSGM film on the porous anode support, and the required phase composition of the LSGM film were obtained simultaneously by sintering at 1400 ℃ for 6 h. The adhesion between the LSGM film and the porous anode support is very strong. The electrical conductivities of the LSGM film on the porous anode support are 0. 113 and 0. 173 S/cm at 800 and 850℃, respectively. The maximum output power density of the LSGM film cell is 177 mW/cm^2 at 700℃.展开更多
基金Project (Nos. 51106136 and 50776078) supported by the National Natural Science Foundation of China
文摘The fuel dynamic transfer process,including fuel injection,fuel film deposition and evaporation in the intake port,was analyzed for spark ignition(SI) engines with port fuel injection(PFI).The influence of wall-wetting fuel film,especially its evaporation rate,upon the air-fuel ratio of in-cylinder mixtures was also discussed.According to the similarity principle,Fick's law,the ideal gas equation and the Gilliland correlation,an evaporate prediction model of wall-wetting fuel film was set up and an evaporate prediction based dynamic fuel film compensator was designed.Through engine cold start tests,the wall-wetting temperature,which is the key input of the fuel film evaporate prediction model,was also modeled and predicted.Combined with the experimental data of the evaporation characteristics of ethanol-gasoline blends and engine calibration tests,all the parameters of the wall-wetting fuel film evaporate prediction model used in the fuel film compensator were identified.Square-wave disturbance tests of fuel injection showed that with the help of the fuel film compensator the response of the in-cylinder air-fuel ratio was significantly improved and the real air-fuel ratio always closely matched the expected ratio.The fuel film compensator was then integrated into the final air-fuel ratio controller,and the engine tests showed that the air-fuel ratio control error was less than 2% in steady-state conditions,and less than 4% in transient conditions.The fuel film compensator also showed good adaptability to different ethanol-gasoline blends.
文摘One of the proposed concepts for spark ignition engines is advanced port fuel injection(APFI),which suggests using two port injectors for each cylinder.In this research,we numerically examine the capabilities of this concept in reducing fuel consumption and increasing engine performance.The results demonstrated that the use of this concept is very effective due to the use of two injectors and the possibility of reducing the spraying time and bringing the injection start time closer to the air inlet valve opening time.The maximum amount of fuel film formed on the walls is reduced by about 75%,naturally,which leads to better and more homogeneous fuel distribution inside the combustion chamber and increases combustion efficiency.The results showed that under the same boundary conditions and engine operating point,the use of two port injectors for each cylinder leads to an increase of more than 20%of the maximum combustion chamber pressure and about 4%combustion efficiency.On the other hand,fuel film formation becomes worse in cold conditions.So in this study,the capabilities of this concept in cold conditions were investigated too.Investigations have shown that the advanced port fuel injection,unlike conventional engines,is almost insensitive to inlet temperature changes.
文摘Polyalkylmethacrylates(PAMAs) are well-known as viscosity index improvers and dispersant boosters.This paper shows that PAMAs are able to adsorb from oil solution on to metal surfaces,to produce thick,viscous boundary films.These films enhance lubricant film formation in slow speed and high temperature conditions and thus produce a significant reduction of friction.A systematic study of this phenomenon has made use of the highly flexible nature of PAMA chemistry.A range of dispersant and non-dispersant polymethacrylates has been synthesized.The influence of different functionalities,molecular weights and architectures on both boundary film formation and friction has been explored using optical interferometry and friction-speed charting.From the results, guidelines have been developed for designing PAMAs having optimal boundary lubricating properties.Through their ability to form boundary films PAMAs can significantly contribute to reduce wear in engine,gear and hydraulic lubrication.As a consequence of their viscometric and tribological performance PAMAs can furthermore improve fuel and energy efficiency in different,namely engine and hydraulic applications.Extensive work is currently conducted in the lubricant industry to develop engine oils with lower sulfur,phosphorus and metal content(low SAPS) and to optimize their frictional properties through the use of friction modifiers or synthetic base stocks.We have investigated the contribution of PAMA viscosity index improvers and boosters to improve fuel economy and to reduce wear levels.This paper reports our efforts to develop a new range of PAMAs that have been optimized in terms of composition,architecture,molecular weight and functionality and which can be used in low viscosity,low SAPS formulations to help meet the stringent requirements of modern engine oils.
文摘Sm and Gd co-doped Ceria (SGDC:Sm_(0.1)Gd_(0.1)Ce_(0.8)O_(1.90)) films as the electrolytes were investigated for the IT-SOFCs (intermediate-temperature solid oxide fuel cells).SGDC sensing films were successfully prepared on the Al_2O_3 substrates by RF-magnetron sputtering.The relationship between sputtering parameters and film microstructure was discussed, and the optimum parameters were gained.The crystal structure analysis and surface morphologic observation of the SGDC films were carried out through X-ray diffraction (XRD) and scanning electron microscopy (SEM).The oxygen ion conductivity of the SGDC film was evaluated by AC impedance spectroscopy at the different temperatures.The XRD analysis shows that the SGDC films grow preferentially along the (111) compact plane.The crystallinity of the SGDC films is enhanced with the increase of the RF sputtering power from 150 W to 250 W.The oxygen ion conductivity of the SGDC was measured at the temperature from 600℃to 800℃in air by AC impedance spectroscopy.The result shows that a high oxygen ion conductivity of 2.44×10^(-2) S.cm^(-1) was achieved at 800℃.
基金Supported by Jilin Province Department of Science and Technology(No. 20000322).
文摘A 65. 8-μm dense doped lanthanum gallate La0.8Sr0.2 Ga0.85 Mg0.15 O2.825（LSGM）film was prepared on a porous Ni/SDC（samarium doped ceria, Ce0.8Sm0.2O1.9 ） anode support by colloid susponsion deposition with incomplete crystallization LSGM powder as a starting material. The phase composition and micromorphology of the LSGM film were characterized by X-ray diffraction and scanning electron microscopy. The electrical properties of the LSGM film and the performances of the LSGM film solid oxide fuel cell were also analyzed. The results show that beth the dense LSGM film on the porous anode support, and the required phase composition of the LSGM film were obtained simultaneously by sintering at 1400 ℃ for 6 h. The adhesion between the LSGM film and the porous anode support is very strong. The electrical conductivities of the LSGM film on the porous anode support are 0. 113 and 0. 173 S/cm at 800 and 850℃, respectively. The maximum output power density of the LSGM film cell is 177 mW/cm^2 at 700℃.
