Knowing the optimal operating parameters of Stirling engines is important for efficient combustion through adaptability to changed pressures and oxygen atmospheres. In this study, the optimum operating conditions for ...Knowing the optimal operating parameters of Stirling engines is important for efficient combustion through adaptability to changed pressures and oxygen atmospheres. In this study, the optimum operating conditions for efficient combustion in a singular Stirling engine combustor at different oxygen atmospheres were investigated and determined. Numerical simulations were performed to investigate the effects of ejection ratio and pressure on combustion performance. In an oxygen/carbon dioxide atmosphere, the results show that increasing the ejection ratio substantially alters the flame distribution in the Stirling engine combustor, increasing heat transfer and external combustion efficiency. In contrast, increasing the ejection ratio reduces the average and maximum temperatures of the Stirling engine combustor. Increased pressure affects the flame distribution in the Stirling engine combustor and impedes the flow and convective heat transfer in the combustor, reducing the overall external combustion efficiency at pressures above 6.5 MPa. In an air/carbon dioxide atmosphere, an increased ejection ratio reduces the average and maximum temperatures in the Stirling engine combustor. However, the overall flame distribution does not change substantially. The external combustion efficiency tends to increase and then decrease because of two opposing factors: the increase in the convective heat transfer coefficient and the decrease in the temperature difference. Increasing pressure inhibits forced convection heat transfer in the Stirling engine combustor, reducing external combustion efficiency, which drops from 78% to 65% when pressure increases from 0.2 MPa to 0.5 MPa.展开更多
We propose a restoration strategy using microgrids for restoring power supply to critical loads after an extreme event and thereby enhancing the resilience of the distribution power grid.The limited capacities of dist...We propose a restoration strategy using microgrids for restoring power supply to critical loads after an extreme event and thereby enhancing the resilience of the distribution power grid.The limited capacities of distributed generators(DGs)within the microgrids and those of intermittent energy sources such as wind and photovoltaic power are considered.An enhanced strategy model of the distribution network is established for maximizing the power supply to critical loads.Firstly,the importance of the load is quantified by using the analytic hierarchy process(AHP)and the model of the microgrid output is further improved.In the demand response mechanism,an interruptible load is used to suppress the fluctuation in the distributed power output.Secondly,piecewise linearization method is applied to address the power flow constraints.Then,the resilience enhancement model of the distribution network is transformed into a mixed integer quadratic programming problem.The CPLEX solver is adopted to solve the above problem on the MATLAB platform.Finally,the proposed method is verified by applying it to practical scenarios.展开更多
The economic operation of integrated energy system(IES)faces new challenges such as multi-timescale characteristics of heterogeneous energy sources,and cooperative operation of hybrid energy storage system(HESS).To th...The economic operation of integrated energy system(IES)faces new challenges such as multi-timescale characteristics of heterogeneous energy sources,and cooperative operation of hybrid energy storage system(HESS).To this end,this paper investigates the multi-timescale rolling opti-mization problem for IES integrated with HESS.Firstly,the architecture of IES with HESS is established,a comparative analysis is conducted to evaluate the advantages of the HESS over a single energy storage system(SESS)in stabilizing power fluctuations.Secondly,the dayahead and real-time scheduling cost functions of IES are established,the day-ahead scheduling mainly depends on operation costs of the components in IES,the real-time optimal scheduling adopts the Lya-punov optimization method to schedule the battery and hydrogen energy storage in each time slot,so as to minimize the real-time average scheduling operation cost,and the problem of day-ahead and real-time scheduling error,which caused by the uncertainty of the energy storage is solved by online optimization.Finally,the proposed model is verified to reduce the scheduling operation cost and the dispatching error by performing an arithmetic example analysis of the IES in Shanghai,which provides a reference for the safe and stable operation of the IES.展开更多
“A Craftsman Must Sharpen His Tools to Do His Job,”said Confucius.Nuclear detection and readout techniques are the foundation of particle physics,nuclear physics,and particle astrophysics to reveal the nature of the...“A Craftsman Must Sharpen His Tools to Do His Job,”said Confucius.Nuclear detection and readout techniques are the foundation of particle physics,nuclear physics,and particle astrophysics to reveal the nature of the universe.Also,they are being increasingly used in other disciplines like nuclear power generation,life sciences,environmental sciences,medical sciences,etc.The article reviews the short history,recent development,and trend of nuclear detection and readout techniques,covering Semiconductor Detector,Gaseous Detector,Scintillation Detector,Cherenkov Detector,Transition Radiation Detector,and Readout Techniques.By explaining the principle and using examples,we hope to help the interested reader underst and this research field and bring exciting information to the community.展开更多
This paper performs an experimental evaluation of thermolysis-driven gases generated by the thermal decomposition of 1 M LiPF6+EC/DMC=1/1 v/v electrolytes at various decomposition temperatures,pyrolysis durations,and ...This paper performs an experimental evaluation of thermolysis-driven gases generated by the thermal decomposition of 1 M LiPF6+EC/DMC=1/1 v/v electrolytes at various decomposition temperatures,pyrolysis durations,and oxygen concentrations.Carried out in a home-built autoclave filled with pure helium,the experiment reveals that as the decomposition temperature increases,more types and larger quantities of gases will be released.Specifically,the experimental results demonstrate trends of logistic growth in the volume concentration of CO2,C2H6O,C2H4,CO,and C2H4O2 with the increase of decomposition temperature.With a prolonged pyrolysis duration,while volume concentrations of certain gases,such as CO2,C2H6O,C2H5F,and CO would increase,the concentration of C2H4O2 actually decreases.Moreover,concentrations of both C2H4 and C2H5F will first decrease and reach their minimum values at 1%v/v oxygen concentration,and then they would quickly climb back at higher oxygen concentrations,while the concentrations of C2H6 and C2H3F would decrease monotonically.It is envisioned that the detailed experimental results and findings on the gas generation pattern of 1 M LiPF6+EC/DMC=1/1 v/v electrolytes can facilitate the development of an early warning mechanism of thermal runaway based on gas sensing technology,which can be effectively applied to monitor the potential thermal failures of lithium-ion batteries with the same type of electrolyte and thus promote the thermal safety of battery packs in safety-critical applications.展开更多
基金Supported by the Shanghai Rising Star Program (Grant No. 21QB1403900)the Shanghai Municipal Commission of Science and Technology (Grant No. 22170712600)。
文摘Knowing the optimal operating parameters of Stirling engines is important for efficient combustion through adaptability to changed pressures and oxygen atmospheres. In this study, the optimum operating conditions for efficient combustion in a singular Stirling engine combustor at different oxygen atmospheres were investigated and determined. Numerical simulations were performed to investigate the effects of ejection ratio and pressure on combustion performance. In an oxygen/carbon dioxide atmosphere, the results show that increasing the ejection ratio substantially alters the flame distribution in the Stirling engine combustor, increasing heat transfer and external combustion efficiency. In contrast, increasing the ejection ratio reduces the average and maximum temperatures of the Stirling engine combustor. Increased pressure affects the flame distribution in the Stirling engine combustor and impedes the flow and convective heat transfer in the combustor, reducing the overall external combustion efficiency at pressures above 6.5 MPa. In an air/carbon dioxide atmosphere, an increased ejection ratio reduces the average and maximum temperatures in the Stirling engine combustor. However, the overall flame distribution does not change substantially. The external combustion efficiency tends to increase and then decrease because of two opposing factors: the increase in the convective heat transfer coefficient and the decrease in the temperature difference. Increasing pressure inhibits forced convection heat transfer in the Stirling engine combustor, reducing external combustion efficiency, which drops from 78% to 65% when pressure increases from 0.2 MPa to 0.5 MPa.
基金supported by the State Grid Science&Technology Project(Grant No.17H300000437)
文摘We propose a restoration strategy using microgrids for restoring power supply to critical loads after an extreme event and thereby enhancing the resilience of the distribution power grid.The limited capacities of distributed generators(DGs)within the microgrids and those of intermittent energy sources such as wind and photovoltaic power are considered.An enhanced strategy model of the distribution network is established for maximizing the power supply to critical loads.Firstly,the importance of the load is quantified by using the analytic hierarchy process(AHP)and the model of the microgrid output is further improved.In the demand response mechanism,an interruptible load is used to suppress the fluctuation in the distributed power output.Secondly,piecewise linearization method is applied to address the power flow constraints.Then,the resilience enhancement model of the distribution network is transformed into a mixed integer quadratic programming problem.The CPLEX solver is adopted to solve the above problem on the MATLAB platform.Finally,the proposed method is verified by applying it to practical scenarios.
基金supported by the National Natural Science Foundation of China(No.12171145)。
文摘The economic operation of integrated energy system(IES)faces new challenges such as multi-timescale characteristics of heterogeneous energy sources,and cooperative operation of hybrid energy storage system(HESS).To this end,this paper investigates the multi-timescale rolling opti-mization problem for IES integrated with HESS.Firstly,the architecture of IES with HESS is established,a comparative analysis is conducted to evaluate the advantages of the HESS over a single energy storage system(SESS)in stabilizing power fluctuations.Secondly,the dayahead and real-time scheduling cost functions of IES are established,the day-ahead scheduling mainly depends on operation costs of the components in IES,the real-time optimal scheduling adopts the Lya-punov optimization method to schedule the battery and hydrogen energy storage in each time slot,so as to minimize the real-time average scheduling operation cost,and the problem of day-ahead and real-time scheduling error,which caused by the uncertainty of the energy storage is solved by online optimization.Finally,the proposed model is verified to reduce the scheduling operation cost and the dispatching error by performing an arithmetic example analysis of the IES in Shanghai,which provides a reference for the safe and stable operation of the IES.
文摘为了探明某机枪枪管损伤特征,分析其失效机制,开展了寿命射击试验。采用光学显微镜、扫描电子显微镜、内窥镜和量规对枪管内膛表面进行观察和测量。结果表明,从枪尾至枪口Cr层主要损伤方式为由剥落向磨损转变,根据这个特征,寿终枪管沿轴向可分为剥落区、过渡区和磨损区。从剥落区至磨损区,膛线起始损伤从阴线逐渐向阳线转变。剥落区和磨损区的损伤速率均较高,而过渡区的损伤速率相对缓慢。在剥落区,射弹量为全寿命的27%时阴线出现大块Cr层掉落,射弹量为全寿命的55%时Cr层已完全剥落。在磨损区,射弹量为全寿命的7%时阳线导转侧已发生明显磨损,射弹量为全寿命的7%增至14%时内径从12. 69 mm升至12. 75 mm.
基金supported by the National Natural Science Foundation of China(No.12222512,U2032209,12075045,12335011,1875097,11975257,62074146,11975115,12205374,12305210,11975292,12005276,12005278,12375193,12227805,12235012,12375191,12005279)the National Key Research and Development Program of China(2021YFA1601300)+13 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB34000000)the CAS Pioneer Hundred Talent Programthe CAS“Light of West China”Programthe Natural Science Foundation of Liaoning Province(No.101300261)the Dalian Science and Technology Innovation Fund(2023JJ12GX013)the Special Projects of the Central Government in Guidance of Local Science and Technology Development(Research and development of three-dimensional prospecting technology based on Cosmic-ray muons)(YDZX20216200001297)the Science and Technology Planning Project of Gansu(20JR10RA645)the Lanzhou University Talent Cooperation Research Funds sponsored by both Lanzhou City(561121203)the Gansu provincial science and technology plan projects for talents(054000029)the Beijing Natural Science Foundation(No.1232033)the Beijing Hope Run Special Fund of Cancer Foundation of China(No.LC2021B23)the Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030008)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(No.GJJSTD20210009)the Youth Innovation Promotion Association CAS(2021450)。
文摘“A Craftsman Must Sharpen His Tools to Do His Job,”said Confucius.Nuclear detection and readout techniques are the foundation of particle physics,nuclear physics,and particle astrophysics to reveal the nature of the universe.Also,they are being increasingly used in other disciplines like nuclear power generation,life sciences,environmental sciences,medical sciences,etc.The article reviews the short history,recent development,and trend of nuclear detection and readout techniques,covering Semiconductor Detector,Gaseous Detector,Scintillation Detector,Cherenkov Detector,Transition Radiation Detector,and Readout Techniques.By explaining the principle and using examples,we hope to help the interested reader underst and this research field and bring exciting information to the community.
基金supported by the National Natural Science Foundation of China(51877203)the Science and Technology Foundation of State Grid Corporation of China(521205190014).
文摘This paper performs an experimental evaluation of thermolysis-driven gases generated by the thermal decomposition of 1 M LiPF6+EC/DMC=1/1 v/v electrolytes at various decomposition temperatures,pyrolysis durations,and oxygen concentrations.Carried out in a home-built autoclave filled with pure helium,the experiment reveals that as the decomposition temperature increases,more types and larger quantities of gases will be released.Specifically,the experimental results demonstrate trends of logistic growth in the volume concentration of CO2,C2H6O,C2H4,CO,and C2H4O2 with the increase of decomposition temperature.With a prolonged pyrolysis duration,while volume concentrations of certain gases,such as CO2,C2H6O,C2H5F,and CO would increase,the concentration of C2H4O2 actually decreases.Moreover,concentrations of both C2H4 and C2H5F will first decrease and reach their minimum values at 1%v/v oxygen concentration,and then they would quickly climb back at higher oxygen concentrations,while the concentrations of C2H6 and C2H3F would decrease monotonically.It is envisioned that the detailed experimental results and findings on the gas generation pattern of 1 M LiPF6+EC/DMC=1/1 v/v electrolytes can facilitate the development of an early warning mechanism of thermal runaway based on gas sensing technology,which can be effectively applied to monitor the potential thermal failures of lithium-ion batteries with the same type of electrolyte and thus promote the thermal safety of battery packs in safety-critical applications.
