Replacing the conventional carbonate electrolyte by solid-state electrolyte (SSE) will offer improved safety for lithium-ion batteries.To further improve the energy density,Silicon (Si) is attractive for next generati...Replacing the conventional carbonate electrolyte by solid-state electrolyte (SSE) will offer improved safety for lithium-ion batteries.To further improve the energy density,Silicon (Si) is attractive for next generation solid-state battery (SSB) because of its high specific capacity and low cost.High energy density and safe Si-based SSB,however,is plagued by large volume change that leads to poor mechanical stability and slow lithium ions transportation at the multiple interfaces between Si and SSE.Herein,we designed a self-integrated and monolithic Si/two dimensional layered T_(3)C_(2)T_(x)(MXene,T_(x) stands for terminal functional groups) electrode architecture with interfacial nitrogen engineering.During a heat treatment process,the polyacrylonitrile not only converts into amorphous carbon (a-C) that shells Si but also forms robust interfacial nitrogen chemical bonds that anchors Si and MXene.During repeated lithiation and delithiation processes,the robust interfacial engineered Si/MXene configuration enhances the mechanical adhesion between Si and MXene that improves the structure stability but also contributes to form stable solid-electrolyte interphase (SEI).In addition,the N-MXene provides fast lithium ions transportation pathways.Consequently,the Si/MXene with interfacial nitrogen engineering (denoted as Si-N-MXene) deliveres high-rate performance with a specific capacity of 1498 m Ah g^(-1) at a high current of 6.4 A g^(-1).A Si-N-MXene/NMC full cell exhibited a capacity retention of 80.5%after 200 cycles.The Si-N-MXene electrode is also applied to SSB and shows a relative stable cycling over 100 cycles,demonstrating the versatility of this concept.展开更多
A three dimensional model which considers the effects of turbulence and detailed chemi cal kinetics is built to simulate the combustion process of engine fueled by compressed nature gas （CNG）. The model is accompli...A three dimensional model which considers the effects of turbulence and detailed chemi cal kinetics is built to simulate the combustion process of engine fueled by compressed nature gas （CNG）. The model is accomplished by integrating CFD software KIVA3V and chemical kinetic soft- ware CHEMKINII. Meanwhile, a turbulence combustion model which is suitable for describing the reaction rate under the coupled simulation is developed to balance the effects of turbulence and de tailed chemical kinetics. To reduce the computation time, subsequent development of the simulation code is realized, which enables the simulation code to have the function of parallel computing and run on parallel computing facility based on message passing interface （MPI）. The coupled software is used to simulate the combustion process of spark ignition CNG engine. The results show that sim ulation data have a good consistency with experimental results and parallel computing has good effi ciency and accelerate ratio.展开更多
Fast depletion of fossil fuels with its resources already passed its mid depletion region and the pollution levels already reached unsafe levels which make it utmost necessity to search for alternative fuels to meet s...Fast depletion of fossil fuels with its resources already passed its mid depletion region and the pollution levels already reached unsafe levels which make it utmost necessity to search for alternative fuels to meet sustainable energy demand with minimum environmental impact. Among alternative fuels, hydrogen is considered as the near future, long term renewable, sustainable and non-polluting fuel. In the present paper, hydrogen fueled internal combustion engine fundamentals highlighted and presented relating to hydrogen combustion properties. A Mat lab programmed hydrogen temperature-entropy-energy chart is developed and presented for fresh charge and products of combustion at different excess air factors per mole combustion gases. The chart, then, used to represent a SI hydrogen-fueled fuel/air cycle analysis, which proved to be valuable design tool for engine sizing and for prediction of engine performance. Predictions carried out using the hydrogen F/A cycle analysis at different λ show low brake specific fuel consumption and low volume specific power compared with conventional SI engine.展开更多
As the practicability of a hydrogen-fueled economy emerges, intermediate technologies would be necessary for the transition between hydrocarbon fueled internal combustion engines and hydrogen powered fuel cells. In th...As the practicability of a hydrogen-fueled economy emerges, intermediate technologies would be necessary for the transition between hydrocarbon fueled internal combustion engines and hydrogen powered fuel cells. In the present study, the hydrogen engine efficiency and the load control are the two main parameters that will be improved by using the combined operation of in-cylinder direct fuel injection (DI) and port fuel injection (PFI) strategies to obtain maximum engine power outputs with acceptable efficiency equivalent to gasoline engines. Wide open throttle (WOT) operation has been used to take advantage of the associated increase in engine efficiency, in which the loads have been regulated with mixture richness (qualitative control) instead of volumetric efficiency (quantitative control). The capabilities of a 3D-CFD code have been developed and employed to simulate the whole engine physicochemical process which includes the hydrogen injection through the intake manifold (PFI) and/or the hydrogen DI in the engine compression stroke. Conditions with simulated PFI, PFI + DI and DI have been analyzed to study the effects of mixture preparation behaviors on the hydrogen ignition and its flame propagation inside the engine combustion chamber. Numerically, the CFD code has been intensively validated against experimental engine data which provided remarkable agreement in terms of in-cylinder pressure history evaluation.展开更多
The intake air control system of a gasoline engine is a typical nonlinear system, and included among the adverse fac-tors that always induce poor idle-speed control stability are dead time and disturbances in the inta...The intake air control system of a gasoline engine is a typical nonlinear system, and included among the adverse fac-tors that always induce poor idle-speed control stability are dead time and disturbances in the intake air control process. In this paper, to improve the responsiveness when idling with regard to disturbances, a mean-value engine model (MVEM) with dead time was constructed as the control object, and the two servo structures of sliding mode control (SMC) were studied for better idle control performance, especially in transient process of speed change. The simulation results confirmed that under the constraint condition of control input, the robustness of idle speed control that is being subjected to torque disturbances and noise disturbances can be greatly improved by use of the servo structure II.展开更多
NOx and soot emissions from diesel engines can be greatly reduced by pressure wave supercharging(PWS).The diesel engine matched with PWS needs redesigning its exhaust pipes.Except for meeting the installation requirem...NOx and soot emissions from diesel engines can be greatly reduced by pressure wave supercharging(PWS).The diesel engine matched with PWS needs redesigning its exhaust pipes.Except for meeting the installation requirements,the exhaust gas must be stable in pressure before rushing into PWS.In this paper the lateral and center ported divergent exhaust pipes are designed,modeled geometrically and analyzed structurally based on a 3-D design software-CATIA to determine the structure of two exhaust pipes having the required inner volume.Then flow analysis for two exhaust pipes is done using a flow analysis software-ANASYS.Moreover,the optimal exhaust pipes are determined comprehensively and cast for engine test.Engine test results show that PWS is superior to turbocharging at low engine speeds and inferior to turbocharging in power and emissions at medium-to-high engine speeds.The performance of PWS engine under high speed operating conditions can be improved by contriving larger surge volume intake and exhaust pipes.展开更多
In this paper, experimental investigations are presented to assess the performance variations in a single cylinder spark ignited engine when run with three different gasoline-alcohol blends： （88% gasoline-12% methan...In this paper, experimental investigations are presented to assess the performance variations in a single cylinder spark ignited engine when run with three different gasoline-alcohol blends： （88% gasoline-12% methanol, 88% gasoline-12% ethanol and 88% gasoline-6% methanol-6% ethanol）. Additional tests are carried out with the basic gasoline fuel for comparison analysis and performance assessment. Engine performance is investigated under a variety of engine operating conditions. The results are presented in the domain of engine speed. In particular, the brake power of the engine is shown to be slightly increased. The brake thermal efficiency showed an increase compared with the basic gasoline engine. Similarly, it is shown that brake specific fuel consumption is enhanced compared with basic gasoline engine. The exhaust gas temperature showed a decrease compared with gasoline fuel which is preferable to reduce emissions. The alcohol additives are strongly recommended to enhance performance, increasing the mileage and reducing the emissions.展开更多
基金supported by the National Natural Science Foundation of China(51902165,12004145,52072323)the Natural Science Foundation of Jiangsu Province(BK20200800)+2 种基金the Natural Science Foundation of Jiangxi Province(20192ACBL20048)the Jiangxi Provincial Natural Science Foundation(20212BAB214032)the Nanjing Science&Technology Innovation Project for Personnel Studying Abroad。
文摘Replacing the conventional carbonate electrolyte by solid-state electrolyte (SSE) will offer improved safety for lithium-ion batteries.To further improve the energy density,Silicon (Si) is attractive for next generation solid-state battery (SSB) because of its high specific capacity and low cost.High energy density and safe Si-based SSB,however,is plagued by large volume change that leads to poor mechanical stability and slow lithium ions transportation at the multiple interfaces between Si and SSE.Herein,we designed a self-integrated and monolithic Si/two dimensional layered T_(3)C_(2)T_(x)(MXene,T_(x) stands for terminal functional groups) electrode architecture with interfacial nitrogen engineering.During a heat treatment process,the polyacrylonitrile not only converts into amorphous carbon (a-C) that shells Si but also forms robust interfacial nitrogen chemical bonds that anchors Si and MXene.During repeated lithiation and delithiation processes,the robust interfacial engineered Si/MXene configuration enhances the mechanical adhesion between Si and MXene that improves the structure stability but also contributes to form stable solid-electrolyte interphase (SEI).In addition,the N-MXene provides fast lithium ions transportation pathways.Consequently,the Si/MXene with interfacial nitrogen engineering (denoted as Si-N-MXene) deliveres high-rate performance with a specific capacity of 1498 m Ah g^(-1) at a high current of 6.4 A g^(-1).A Si-N-MXene/NMC full cell exhibited a capacity retention of 80.5%after 200 cycles.The Si-N-MXene electrode is also applied to SSB and shows a relative stable cycling over 100 cycles,demonstrating the versatility of this concept.
基金Supported by the National Natural Science Foundation of China(50976012)
文摘A three dimensional model which considers the effects of turbulence and detailed chemi cal kinetics is built to simulate the combustion process of engine fueled by compressed nature gas （CNG）. The model is accomplished by integrating CFD software KIVA3V and chemical kinetic soft- ware CHEMKINII. Meanwhile, a turbulence combustion model which is suitable for describing the reaction rate under the coupled simulation is developed to balance the effects of turbulence and de tailed chemical kinetics. To reduce the computation time, subsequent development of the simulation code is realized, which enables the simulation code to have the function of parallel computing and run on parallel computing facility based on message passing interface （MPI）. The coupled software is used to simulate the combustion process of spark ignition CNG engine. The results show that sim ulation data have a good consistency with experimental results and parallel computing has good effi ciency and accelerate ratio.
文摘Fast depletion of fossil fuels with its resources already passed its mid depletion region and the pollution levels already reached unsafe levels which make it utmost necessity to search for alternative fuels to meet sustainable energy demand with minimum environmental impact. Among alternative fuels, hydrogen is considered as the near future, long term renewable, sustainable and non-polluting fuel. In the present paper, hydrogen fueled internal combustion engine fundamentals highlighted and presented relating to hydrogen combustion properties. A Mat lab programmed hydrogen temperature-entropy-energy chart is developed and presented for fresh charge and products of combustion at different excess air factors per mole combustion gases. The chart, then, used to represent a SI hydrogen-fueled fuel/air cycle analysis, which proved to be valuable design tool for engine sizing and for prediction of engine performance. Predictions carried out using the hydrogen F/A cycle analysis at different λ show low brake specific fuel consumption and low volume specific power compared with conventional SI engine.
文摘As the practicability of a hydrogen-fueled economy emerges, intermediate technologies would be necessary for the transition between hydrocarbon fueled internal combustion engines and hydrogen powered fuel cells. In the present study, the hydrogen engine efficiency and the load control are the two main parameters that will be improved by using the combined operation of in-cylinder direct fuel injection (DI) and port fuel injection (PFI) strategies to obtain maximum engine power outputs with acceptable efficiency equivalent to gasoline engines. Wide open throttle (WOT) operation has been used to take advantage of the associated increase in engine efficiency, in which the loads have been regulated with mixture richness (qualitative control) instead of volumetric efficiency (quantitative control). The capabilities of a 3D-CFD code have been developed and employed to simulate the whole engine physicochemical process which includes the hydrogen injection through the intake manifold (PFI) and/or the hydrogen DI in the engine compression stroke. Conditions with simulated PFI, PFI + DI and DI have been analyzed to study the effects of mixture preparation behaviors on the hydrogen ignition and its flame propagation inside the engine combustion chamber. Numerically, the CFD code has been intensively validated against experimental engine data which provided remarkable agreement in terms of in-cylinder pressure history evaluation.
文摘The intake air control system of a gasoline engine is a typical nonlinear system, and included among the adverse fac-tors that always induce poor idle-speed control stability are dead time and disturbances in the intake air control process. In this paper, to improve the responsiveness when idling with regard to disturbances, a mean-value engine model (MVEM) with dead time was constructed as the control object, and the two servo structures of sliding mode control (SMC) were studied for better idle control performance, especially in transient process of speed change. The simulation results confirmed that under the constraint condition of control input, the robustness of idle speed control that is being subjected to torque disturbances and noise disturbances can be greatly improved by use of the servo structure II.
文摘NOx and soot emissions from diesel engines can be greatly reduced by pressure wave supercharging(PWS).The diesel engine matched with PWS needs redesigning its exhaust pipes.Except for meeting the installation requirements,the exhaust gas must be stable in pressure before rushing into PWS.In this paper the lateral and center ported divergent exhaust pipes are designed,modeled geometrically and analyzed structurally based on a 3-D design software-CATIA to determine the structure of two exhaust pipes having the required inner volume.Then flow analysis for two exhaust pipes is done using a flow analysis software-ANASYS.Moreover,the optimal exhaust pipes are determined comprehensively and cast for engine test.Engine test results show that PWS is superior to turbocharging at low engine speeds and inferior to turbocharging in power and emissions at medium-to-high engine speeds.The performance of PWS engine under high speed operating conditions can be improved by contriving larger surge volume intake and exhaust pipes.
文摘In this paper, experimental investigations are presented to assess the performance variations in a single cylinder spark ignited engine when run with three different gasoline-alcohol blends： （88% gasoline-12% methanol, 88% gasoline-12% ethanol and 88% gasoline-6% methanol-6% ethanol）. Additional tests are carried out with the basic gasoline fuel for comparison analysis and performance assessment. Engine performance is investigated under a variety of engine operating conditions. The results are presented in the domain of engine speed. In particular, the brake power of the engine is shown to be slightly increased. The brake thermal efficiency showed an increase compared with the basic gasoline engine. Similarly, it is shown that brake specific fuel consumption is enhanced compared with basic gasoline engine. The exhaust gas temperature showed a decrease compared with gasoline fuel which is preferable to reduce emissions. The alcohol additives are strongly recommended to enhance performance, increasing the mileage and reducing the emissions.
