Complex energy and environment system, especially nuclear fuel cycle system recently raised socialconcerns about the issues of economic competitiveness, environmental effect and nuclear proliferation. Only underthe co...Complex energy and environment system, especially nuclear fuel cycle system recently raised socialconcerns about the issues of economic competitiveness, environmental effect and nuclear proliferation. Only underthe condition that those conflicting issues are gotten a consensus between stakeholders with different knowledgebackground, can nuclear power industry be continuingly developed. In this paper, a new analysis platform has beendeveloped to help stakeholders to recognize and analyze various socio-technical issues in the nuclear fuel cycle systembased on the functional modeling method named Multilevel Flow Models (MFM) according to the cognition theoryof human being. Its character is that MFM models define a set of mass, energy and information flow structures onmultiple levels of abstraction to describe the functional structure of a process system and its graphical symbol representationand the means-end and part-whole hierarchical flow structure to make the represented process easy to beunderstood. Based upon this methodology, a micro-process and a macro-process of nuclear fuel cycle system wereselected to be simulated and some analysis processes such as economics analysis, environmental analysis and energybalance analysis related to those flows were also integrated to help stakeholders to understand the process of decision-making with the introduction of some new functions for the improved Multilevel Flow Models Studio, and finallythe simple simulation such as spent fuel management process simulation and money flow of nuclear fuel cycleand its levelised cost analysis will be represented as feasible examples.展开更多
Biomass ethanol fuel is not only renewable but also environmental-friendly. Guangxi Zhuang Autonomous Region is developing the cassava-based ethanol fuel. Economical performance of the project is the key issue. The tr...Biomass ethanol fuel is not only renewable but also environmental-friendly. Guangxi Zhuang Autonomous Region is developing the cassava-based ethanol fuel. Economical performance of the project is the key issue. The traditional life cycle economical analysis is just a static calculation process. Uncertainty is the character of cassava yield, cost of cassava plant, cassava price, tax rate and gasoline price, and the economical performance of the project is determined by these aspects. This study proposes an economical model of cassava-based ethanol fuel. The method of Monte Carol is used to simulate the economical performance. This method conquers the shortage of the traditional way. The results show that cassava-based ethanol fuel can get survived when the tax is exempted. Finally, the study also evaluates the potential of the economical performance.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
A combined system model is proposed including a molten carbonate fuel cell(MCFC),a graphene thermionic converter(GTIC)and thermally regenerative electrochemical cycles(TRECs).The expressions for power output,energy ef...A combined system model is proposed including a molten carbonate fuel cell(MCFC),a graphene thermionic converter(GTIC)and thermally regenerative electrochemical cycles(TRECs).The expressions for power output,energy efficiency of the subsystems and the couple system are formulated by considering several irreversible losses.Energy conservation equations between the subsystems are achieved leaned on the first law of thermodynamics.The optimum operating ranges for the combined system are determined compared with the MCFC system.Results reveal that the peak power output density(POD)and the corresponding energy efficiency are 28.22%and 10.76%higher than that of the single MCFC system,respectively.The effects of five designing parameters on the power density and energy efficiency of the MCFC/GTIC/TRECs model are also investigated and discussed.展开更多
An improvement in the corrosion resistance of alloys at elevated temperature is a factor for their potential use in gas turbines. In this study, Co Ni Cr Al Y has been coated on the L605 alloy using air plasma spray(A...An improvement in the corrosion resistance of alloys at elevated temperature is a factor for their potential use in gas turbines. In this study, Co Ni Cr Al Y has been coated on the L605 alloy using air plasma spray(APS) and high-velocity oxygen fuel(HVOF) coating techniques to enhance its corrosion resistance. Hot corrosion studies were conducted on uncoated and coated samples in a molten salt environment at 850°C under cyclic conditions. Thermogravimetric analysis was used to determine the corrosion kinetics. The samples were subjected to scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction for further investigation. In coated samples, the formation of Al2O3 and Cr2O3 in the coating acts as a diffusion barrier that could resists the inward movement of the corrosive species present in the molten salt. Coated samples showed very less spallation, lower weight gain, less porosity, and internal oxidation as compared to uncoated sample.HVOF-coated sample showed greater corrosion resistance and inferred that this is the best technique under these conditions.展开更多
The objective of this study was to assess the performance of an old existing medical waste incinerator in a district (Temeke) hospital. The medical waste incinerated was grouped into two categories: sharps waste and o...The objective of this study was to assess the performance of an old existing medical waste incinerator in a district (Temeke) hospital. The medical waste incinerated was grouped into two categories: sharps waste and other waste. The parameters assessed included amounts of sharps and other waste incinerated, amount of fuel used and the incineration cycle time. One incineration cycle was conducted per day and data was collected for 22 months (N = 653). It was established that the total waste incinerated per day ranged from 70 to 120 kg, completing the process between 2 and 4 hrs and consuming 20 to 40 L of fuel per day. The analysis showed further that sharps waste incinerated were 25% of the total waste while other waste incinerated were about 75% on average. The average diesel oil used was 30 L/day and average cycle time was observed to be 3 hrs, both being excessively high indicating that the performance of the incin-erator was poor. The statistical analysis was used to reveal stronger variations in other waste than sharps waste. The PDF plots, skewness and kurtosis values indicated that there were weak variations in the daily diesel oil consumed and incineration cycle time while stronger variations were observed in the other waste compared to sharps waste data. Normalization of the incinerator performance data allowed comparison between different data types also indicating poor performance of the incinerator. Proper segregation at point of generation and proper storage of medical waste was recommended. It was further recommended for the hospital to install a new and efficient incinerator with short incineration cycle time and less fuel consumption.展开更多
液态空气储能(liquid air energy storage,LAES)因其不受地理限制和储能密度高的特点,已经成为一种极具发展潜力的大规模储能技术。为了进一步提升LAES系统往返效率,提出一种耦合钢铁余热与有机朗肯循环(organic Rankine cycle,ORC)的新...液态空气储能(liquid air energy storage,LAES)因其不受地理限制和储能密度高的特点,已经成为一种极具发展潜力的大规模储能技术。为了进一步提升LAES系统往返效率,提出一种耦合钢铁余热与有机朗肯循环(organic Rankine cycle,ORC)的新型LAES系统,该集成系统不仅能有效回收钢铁余热,还能显著提升LAES系统性能。通过建立集成系统的热力学模型,利用仿真计算对集成系统关键参数进行了热力性能敏感性分析和优化,开展了系统热力学分析评价。结果表明:不同有机工质随着有机透平进口温度的升高,其输入功率呈现先减小后增加的趋势,ORC效率和系统往返效率则都表现出先增大后减小的特征,且极值出现在临界温度附近。当热源温度从200℃升高到300℃时,系统输出功率从37.3 MW提升至51.9 MW。在最佳工况下,集成系统的电换电效率为118.66%,热电效率为35.62%。(火用)分析表明,膨胀机、冷却器与汽化器是主要(火用)损失源,需通过设备优化与温差调控进一步提升效率。研究成果可为LAES系统的效率提升和钢铁余热利用技术创新提供了重要的理论参考。展开更多
Aerosols represent an important source of terrestrial organic carbon(OC)from the East Asian continent to the China marginal seas,thus their provenance and transport play important roles in the global carbon cycle.Fift...Aerosols represent an important source of terrestrial organic carbon(OC)from the East Asian continent to the China marginal seas,thus their provenance and transport play important roles in the global carbon cycle.Fifty samples of total suspended particle were collected seasonally from the nearshore Huaniao Island(HNI)in East China Sea(ECS)from April 2018 to January 2019;and they were analyzed for total organic carbon(TOC)content and stable carbon isotope(δ^(13)C),as well as terrestrial bio-markers including n-alkanes(C_(20)-C_(33)),n-alkanols(C_(20)-C32)and n-fatty acids(n-FAs,C_(20)-C30),to distinguish the seasonal variabili-ties of terrestrial OC sources and reveal the influence of the long-range air mass transport on these sources.The TOC-δ^(13)C values(range from−27.3‰to−24.3‰)and molecular distributions of terrestrial biomarkers both suggested that terrestrial OC contribu-tions to aerosols had significant seasonal variations.The source indices of terrestrial biomarkers(e.g.,Fossil%=82.8%for n-alkanes)revealed that the fossil fuel OC contributions,including coal burning and vehicular emission,were higher in winter,mainly because of the long-range air mass transport from the north of the East Asian continent.The terrestrial plant OC contributions were higher in summer(e.g.,Wax%=32.4%for n-alkanes),likely due to local vegetation sources from HNI and East Asian continental air masses.Cluster analysis of air mass backward-trajectories clearly showed that transport pathway plays an important role in determining the organic constituents of aerosols in China marginal seas.A comparison of these terrestrial OC contributions from different air mass origins suggested that fossil fuel OC showed less variations among various air mass origins from northern China in winter,while terrestrial plant OC sources from northern and southern China in summer contributed more than that from the air masses transported through the ECS.These results provided a basis for future quantification of terrestrial OC from different origins in marine aerosols,by combining biomarker index and carbon isotopes.展开更多
【目的】天然气补燃型压缩空气储能(compressed air energy storage,CAES)系统存在环境污染问题,氢气作为替代燃料不会造成温室气体排放,但现阶段对纯氢补燃型CAES系统的技术经济可行性认识不足,因此有必要开展相关研究。【方法】基于[...【目的】天然气补燃型压缩空气储能(compressed air energy storage,CAES)系统存在环境污染问题,氢气作为替代燃料不会造成温室气体排放,但现阶段对纯氢补燃型CAES系统的技术经济可行性认识不足,因此有必要开展相关研究。【方法】基于[火用]和[火用]经济分析方法,进行了纯氢补燃型和天然气补燃型CAES系统的对比分析,重点关注其热力学性能、不可逆损失分布、经济性和[火用]经济性的影响。此外,探讨了两者参数敏感性。【结果】纯氢补燃型CAES系统在放电时间、储能密度和[火用]效率方面均优于天然气补燃型CAES系统;由于氢气成本高于天然气,纯氢补燃型CAES系统的产品平均[火用]成本为155.62美元/GJ,显著高于天然气补燃型CAES系统对应的27.57美元/GJ;为使纯氢补燃型CAES系统具备与天然气补燃型CAES系统相同的商用竞争力,推荐售电价格为0.2062美元/(kW·h);此外,纯氢补燃型CAES系统对参数变化更加敏感,在高参数条件下可实现更好的性能提升和成本降低。【结论】研究成果揭示了纯氢补燃型CAES系统的应用潜力,并为其进一步商业推广提供了技术参考。展开更多
文摘Complex energy and environment system, especially nuclear fuel cycle system recently raised socialconcerns about the issues of economic competitiveness, environmental effect and nuclear proliferation. Only underthe condition that those conflicting issues are gotten a consensus between stakeholders with different knowledgebackground, can nuclear power industry be continuingly developed. In this paper, a new analysis platform has beendeveloped to help stakeholders to recognize and analyze various socio-technical issues in the nuclear fuel cycle systembased on the functional modeling method named Multilevel Flow Models (MFM) according to the cognition theoryof human being. Its character is that MFM models define a set of mass, energy and information flow structures onmultiple levels of abstraction to describe the functional structure of a process system and its graphical symbol representationand the means-end and part-whole hierarchical flow structure to make the represented process easy to beunderstood. Based upon this methodology, a micro-process and a macro-process of nuclear fuel cycle system wereselected to be simulated and some analysis processes such as economics analysis, environmental analysis and energybalance analysis related to those flows were also integrated to help stakeholders to understand the process of decision-making with the introduction of some new functions for the improved Multilevel Flow Models Studio, and finallythe simple simulation such as spent fuel management process simulation and money flow of nuclear fuel cycleand its levelised cost analysis will be represented as feasible examples.
文摘Biomass ethanol fuel is not only renewable but also environmental-friendly. Guangxi Zhuang Autonomous Region is developing the cassava-based ethanol fuel. Economical performance of the project is the key issue. The traditional life cycle economical analysis is just a static calculation process. Uncertainty is the character of cassava yield, cost of cassava plant, cassava price, tax rate and gasoline price, and the economical performance of the project is determined by these aspects. This study proposes an economical model of cassava-based ethanol fuel. The method of Monte Carol is used to simulate the economical performance. This method conquers the shortage of the traditional way. The results show that cassava-based ethanol fuel can get survived when the tax is exempted. Finally, the study also evaluates the potential of the economical performance.
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A combined system model is proposed including a molten carbonate fuel cell(MCFC),a graphene thermionic converter(GTIC)and thermally regenerative electrochemical cycles(TRECs).The expressions for power output,energy efficiency of the subsystems and the couple system are formulated by considering several irreversible losses.Energy conservation equations between the subsystems are achieved leaned on the first law of thermodynamics.The optimum operating ranges for the combined system are determined compared with the MCFC system.Results reveal that the peak power output density(POD)and the corresponding energy efficiency are 28.22%and 10.76%higher than that of the single MCFC system,respectively.The effects of five designing parameters on the power density and energy efficiency of the MCFC/GTIC/TRECs model are also investigated and discussed.
文摘An improvement in the corrosion resistance of alloys at elevated temperature is a factor for their potential use in gas turbines. In this study, Co Ni Cr Al Y has been coated on the L605 alloy using air plasma spray(APS) and high-velocity oxygen fuel(HVOF) coating techniques to enhance its corrosion resistance. Hot corrosion studies were conducted on uncoated and coated samples in a molten salt environment at 850°C under cyclic conditions. Thermogravimetric analysis was used to determine the corrosion kinetics. The samples were subjected to scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction for further investigation. In coated samples, the formation of Al2O3 and Cr2O3 in the coating acts as a diffusion barrier that could resists the inward movement of the corrosive species present in the molten salt. Coated samples showed very less spallation, lower weight gain, less porosity, and internal oxidation as compared to uncoated sample.HVOF-coated sample showed greater corrosion resistance and inferred that this is the best technique under these conditions.
文摘The objective of this study was to assess the performance of an old existing medical waste incinerator in a district (Temeke) hospital. The medical waste incinerated was grouped into two categories: sharps waste and other waste. The parameters assessed included amounts of sharps and other waste incinerated, amount of fuel used and the incineration cycle time. One incineration cycle was conducted per day and data was collected for 22 months (N = 653). It was established that the total waste incinerated per day ranged from 70 to 120 kg, completing the process between 2 and 4 hrs and consuming 20 to 40 L of fuel per day. The analysis showed further that sharps waste incinerated were 25% of the total waste while other waste incinerated were about 75% on average. The average diesel oil used was 30 L/day and average cycle time was observed to be 3 hrs, both being excessively high indicating that the performance of the incin-erator was poor. The statistical analysis was used to reveal stronger variations in other waste than sharps waste. The PDF plots, skewness and kurtosis values indicated that there were weak variations in the daily diesel oil consumed and incineration cycle time while stronger variations were observed in the other waste compared to sharps waste data. Normalization of the incinerator performance data allowed comparison between different data types also indicating poor performance of the incinerator. Proper segregation at point of generation and proper storage of medical waste was recommended. It was further recommended for the hospital to install a new and efficient incinerator with short incineration cycle time and less fuel consumption.
文摘液态空气储能(liquid air energy storage,LAES)因其不受地理限制和储能密度高的特点,已经成为一种极具发展潜力的大规模储能技术。为了进一步提升LAES系统往返效率,提出一种耦合钢铁余热与有机朗肯循环(organic Rankine cycle,ORC)的新型LAES系统,该集成系统不仅能有效回收钢铁余热,还能显著提升LAES系统性能。通过建立集成系统的热力学模型,利用仿真计算对集成系统关键参数进行了热力性能敏感性分析和优化,开展了系统热力学分析评价。结果表明:不同有机工质随着有机透平进口温度的升高,其输入功率呈现先减小后增加的趋势,ORC效率和系统往返效率则都表现出先增大后减小的特征,且极值出现在临界温度附近。当热源温度从200℃升高到300℃时,系统输出功率从37.3 MW提升至51.9 MW。在最佳工况下,集成系统的电换电效率为118.66%,热电效率为35.62%。(火用)分析表明,膨胀机、冷却器与汽化器是主要(火用)损失源,需通过设备优化与温差调控进一步提升效率。研究成果可为LAES系统的效率提升和钢铁余热利用技术创新提供了重要的理论参考。
基金This study was supported by the National Natural Science Foundation of China(No.U1706219).This is MCTL(Key Laboratory of Marine Chemistry Theory and Technology)contribution#237.
文摘Aerosols represent an important source of terrestrial organic carbon(OC)from the East Asian continent to the China marginal seas,thus their provenance and transport play important roles in the global carbon cycle.Fifty samples of total suspended particle were collected seasonally from the nearshore Huaniao Island(HNI)in East China Sea(ECS)from April 2018 to January 2019;and they were analyzed for total organic carbon(TOC)content and stable carbon isotope(δ^(13)C),as well as terrestrial bio-markers including n-alkanes(C_(20)-C_(33)),n-alkanols(C_(20)-C32)and n-fatty acids(n-FAs,C_(20)-C30),to distinguish the seasonal variabili-ties of terrestrial OC sources and reveal the influence of the long-range air mass transport on these sources.The TOC-δ^(13)C values(range from−27.3‰to−24.3‰)and molecular distributions of terrestrial biomarkers both suggested that terrestrial OC contribu-tions to aerosols had significant seasonal variations.The source indices of terrestrial biomarkers(e.g.,Fossil%=82.8%for n-alkanes)revealed that the fossil fuel OC contributions,including coal burning and vehicular emission,were higher in winter,mainly because of the long-range air mass transport from the north of the East Asian continent.The terrestrial plant OC contributions were higher in summer(e.g.,Wax%=32.4%for n-alkanes),likely due to local vegetation sources from HNI and East Asian continental air masses.Cluster analysis of air mass backward-trajectories clearly showed that transport pathway plays an important role in determining the organic constituents of aerosols in China marginal seas.A comparison of these terrestrial OC contributions from different air mass origins suggested that fossil fuel OC showed less variations among various air mass origins from northern China in winter,while terrestrial plant OC sources from northern and southern China in summer contributed more than that from the air masses transported through the ECS.These results provided a basis for future quantification of terrestrial OC from different origins in marine aerosols,by combining biomarker index and carbon isotopes.
文摘【目的】天然气补燃型压缩空气储能(compressed air energy storage,CAES)系统存在环境污染问题,氢气作为替代燃料不会造成温室气体排放,但现阶段对纯氢补燃型CAES系统的技术经济可行性认识不足,因此有必要开展相关研究。【方法】基于[火用]和[火用]经济分析方法,进行了纯氢补燃型和天然气补燃型CAES系统的对比分析,重点关注其热力学性能、不可逆损失分布、经济性和[火用]经济性的影响。此外,探讨了两者参数敏感性。【结果】纯氢补燃型CAES系统在放电时间、储能密度和[火用]效率方面均优于天然气补燃型CAES系统;由于氢气成本高于天然气,纯氢补燃型CAES系统的产品平均[火用]成本为155.62美元/GJ,显著高于天然气补燃型CAES系统对应的27.57美元/GJ;为使纯氢补燃型CAES系统具备与天然气补燃型CAES系统相同的商用竞争力,推荐售电价格为0.2062美元/(kW·h);此外,纯氢补燃型CAES系统对参数变化更加敏感,在高参数条件下可实现更好的性能提升和成本降低。【结论】研究成果揭示了纯氢补燃型CAES系统的应用潜力,并为其进一步商业推广提供了技术参考。
