Friction rolling additive manufacturing(FRAM)is a solid-state additive manufacturing technology that plasticizes the feed and deposits a material using frictional heat generated by the tool head.The thermal efficiency...Friction rolling additive manufacturing(FRAM)is a solid-state additive manufacturing technology that plasticizes the feed and deposits a material using frictional heat generated by the tool head.The thermal efficiency of FRAM,which depends only on friction to generate heat,is low,and the thermal-accumulation effect of the deposition process must be addressed.An FRAM heat-balance-control method that combines plasma-arc preheating and instant water cooling(PC-FRAM)is devised in this study,and a temperature field featuring rapidly increasing and decreasing temperature is constructed around the tool head.Additionally,2195-T87 Al-Li alloy is used as the feed material,and the effects of heating and cooling rates on the microstructure and mechanical properties are investigated.The results show that water cooling significantly improves heat accumulation during the deposition process.The cooling rate increases by 11.7 times,and the high-temperature residence time decreases by more than 50%.The grain size of the PC-FRAM sample is the smallest,i.e.,3.77±1.03μm,its dislocation density is the highest,and the number density of precipitates is the highest,the size of precipitates is the smallest,which shows the best precipitation-strengthening effect.The hardness test results are consistent with the precipitation distribution.The ultimate tensile strength,yield strength and elongation of the PC-FRAM samples are the highest(351±15.6 MPa,251.3±15.8 MPa and 16.25%±1.25%,respectively)among the samples investigated.The preheating and water-cooling-assisted deposition simultaneously increases the tensile strength and elongation of the deposited samples.The combination of preheating and instant cooling improves the deposition efficiency of FRAM and weakens the thermal-softening effect.展开更多
针对预热压力容器罐出料口堵塞、颗粒预热不足等性能缺陷,提出融合TRIZ(theory of inventive problem solving)创新理论与数值模拟的系统解决方案。通过构建技术系统功能模型、专创融合解题流程及性能提升框架,结合ARIZ算法生成多方案...针对预热压力容器罐出料口堵塞、颗粒预热不足等性能缺陷,提出融合TRIZ(theory of inventive problem solving)创新理论与数值模拟的系统解决方案。通过构建技术系统功能模型、专创融合解题流程及性能提升框架,结合ARIZ算法生成多方案并优选“设置分流锥”方案。基于颗粒预热数学模型与气固耦合模型,采用ANSYS CFX对60°、90°、120°顶角分流锥的流道工况进行数值模拟,对比分析流速、湍流涡耗散、湍流动能等流场特征,并通过Q-criterion准则解析旋涡结构演化规律。结果表明:上部锥形顶角60°分流锥方案最优,可显著提升流动与预热性能,降低功能退化量;有限单元法验证显示其结构可靠性满足设计要求。可见,提出的方案可谓探索预热压力罐优化设计提供新思路。展开更多
It is presented that a feasibility assessment of solar preheating of steam boiler feed water for opened vapor systems. Data from a medium sized dairy industry near Rio de Janeiro city, in Brazil, is used to compose a ...It is presented that a feasibility assessment of solar preheating of steam boiler feed water for opened vapor systems. Data from a medium sized dairy industry near Rio de Janeiro city, in Brazil, is used to compose a case study. Forty eight solar heating system computer simulations were carried out in TRNSYS （transient system simulation software）, for a range of design parameters corresponding to the 5% best economic results of a series of 2,700 simpler simulations （φ,f-chart method）, programmed on Matlab. It has been used TMY （typical meteorological year） hourly weather data from Rio de Janeiro. Investment cost was composed from both commercial and literature values, while revenue was based on the avoided consumption of fuel for LPG （liquefied petroleum gas）, natural gas and fuel oil, with only the first showing economically feasible. The results, however, made it possible to address environmentally sound public policies to encourage industrial solar energy use.展开更多
With the proposal of China’s“Carbon Peaking and Carbon Neutrality”policy,the steel industry faces urgent pressure to transition toward green and low-carbon development.However,the persistent reliance on burden stru...With the proposal of China’s“Carbon Peaking and Carbon Neutrality”policy,the steel industry faces urgent pressure to transition toward green and low-carbon development.However,the persistent reliance on burden structure dominated by sinter and pellet in China has led to the high energy consumption and pollution emissions in process before ironmaking,which has increasingly become a major obstacle to the green development of the steel industry.Lump ore can be directly charged into blast furnaces without high-temperature roasting,making it a more environmentally friendly and cleaner raw material option.The utilization of lump ore in blast furnace not only has obvious economic advantages but also achieves significant energy saving and carbon reduction effects.Therefore,an overview of the application of natural lump ore resources was provided,with a focus on its metallurgical properties and the factors influencing them.It further analyzed and summarized strategies for optimizing lump ore performance,particularly highlighting the advantages and technical challenges associated with preheating treatments.Additionally,the application experience,changes in technical and economic indicators,as well as the effects of energy saving and carbon reduction under the condition of a high ratio of lump ore in actual production were elaborated in detail.The results show that after loading lump ore to blast furnaces,the raw material cost is reduced by approximately 50.88 CNY/t,and the CO_(2)emissions from the production of 1 t pig iron can be reduced by 51.18 kg.展开更多
Improving energy efficiency and lowering negative environmental impact through waste heat recovery(WHR)is a critical step toward sustainable cement manufacturing.This study analyzes advanced cogeneration systems for r...Improving energy efficiency and lowering negative environmental impact through waste heat recovery(WHR)is a critical step toward sustainable cement manufacturing.This study analyzes advanced cogeneration systems for recovering waste heat from the Fallujah White Cement Plant in Iraq.The novelty of this work lies in its direct application and comparative thermodynamic analysis of three distinct cogeneration cycles—the Organic Rankine Cycle,the Single-Flash Steam Cycle,and the Dual-Pressure Steam Cycle—within the Iraqi cement industry,a context that has not been widely studied.The main objective is to evaluate and compare these models to determine the most effective approach for enhancing energy and exergy efficiencies.Themethodology involved detailed thermodynamic and exergy analyses of each system,supported by mathematical modelling and simulation using data from plant operations.The results reveal that the Dual-Pressure Steam Cycle emerged as the most effective system,delivering 13.76 MW of net power with a thermal efficiency of 32.8%and an exergy efficiency of 51%.This significantly outperformed the baseline Organic Rankine Cycle(8.18MW,18.8%thermal efficiency,30.7%exergy efficiency).These findings confirm that multipressure steam cycles offer a robust and practical solution for the Fallujah plant.This application provides a clear,high-impact pathway to enhance national industrial energy efficiency,significantly reduce CO_(2) emissions,and promote clean energy sustainability in Iraq.Future work should consider economic feasibility and potential integration with renewable energy sources to further enhance sustainability.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52275299,52105313)R&D Program of Beijing Municipal Education Commission(No.KM202210005036)+1 种基金Natural Science Foundation of Chongqing,China(No.CSTB2023NSCQ-MSX0701)National Defense Basic Research Projects of China(No.JCKY2022405C002).
文摘Friction rolling additive manufacturing(FRAM)is a solid-state additive manufacturing technology that plasticizes the feed and deposits a material using frictional heat generated by the tool head.The thermal efficiency of FRAM,which depends only on friction to generate heat,is low,and the thermal-accumulation effect of the deposition process must be addressed.An FRAM heat-balance-control method that combines plasma-arc preheating and instant water cooling(PC-FRAM)is devised in this study,and a temperature field featuring rapidly increasing and decreasing temperature is constructed around the tool head.Additionally,2195-T87 Al-Li alloy is used as the feed material,and the effects of heating and cooling rates on the microstructure and mechanical properties are investigated.The results show that water cooling significantly improves heat accumulation during the deposition process.The cooling rate increases by 11.7 times,and the high-temperature residence time decreases by more than 50%.The grain size of the PC-FRAM sample is the smallest,i.e.,3.77±1.03μm,its dislocation density is the highest,and the number density of precipitates is the highest,the size of precipitates is the smallest,which shows the best precipitation-strengthening effect.The hardness test results are consistent with the precipitation distribution.The ultimate tensile strength,yield strength and elongation of the PC-FRAM samples are the highest(351±15.6 MPa,251.3±15.8 MPa and 16.25%±1.25%,respectively)among the samples investigated.The preheating and water-cooling-assisted deposition simultaneously increases the tensile strength and elongation of the deposited samples.The combination of preheating and instant cooling improves the deposition efficiency of FRAM and weakens the thermal-softening effect.
文摘针对预热压力容器罐出料口堵塞、颗粒预热不足等性能缺陷,提出融合TRIZ(theory of inventive problem solving)创新理论与数值模拟的系统解决方案。通过构建技术系统功能模型、专创融合解题流程及性能提升框架,结合ARIZ算法生成多方案并优选“设置分流锥”方案。基于颗粒预热数学模型与气固耦合模型,采用ANSYS CFX对60°、90°、120°顶角分流锥的流道工况进行数值模拟,对比分析流速、湍流涡耗散、湍流动能等流场特征,并通过Q-criterion准则解析旋涡结构演化规律。结果表明:上部锥形顶角60°分流锥方案最优,可显著提升流动与预热性能,降低功能退化量;有限单元法验证显示其结构可靠性满足设计要求。可见,提出的方案可谓探索预热压力罐优化设计提供新思路。
文摘It is presented that a feasibility assessment of solar preheating of steam boiler feed water for opened vapor systems. Data from a medium sized dairy industry near Rio de Janeiro city, in Brazil, is used to compose a case study. Forty eight solar heating system computer simulations were carried out in TRNSYS （transient system simulation software）, for a range of design parameters corresponding to the 5% best economic results of a series of 2,700 simpler simulations （φ,f-chart method）, programmed on Matlab. It has been used TMY （typical meteorological year） hourly weather data from Rio de Janeiro. Investment cost was composed from both commercial and literature values, while revenue was based on the avoided consumption of fuel for LPG （liquefied petroleum gas）, natural gas and fuel oil, with only the first showing economically feasible. The results, however, made it possible to address environmentally sound public policies to encourage industrial solar energy use.
基金support by National Natural Science Foundation of China(52474342).
文摘With the proposal of China’s“Carbon Peaking and Carbon Neutrality”policy,the steel industry faces urgent pressure to transition toward green and low-carbon development.However,the persistent reliance on burden structure dominated by sinter and pellet in China has led to the high energy consumption and pollution emissions in process before ironmaking,which has increasingly become a major obstacle to the green development of the steel industry.Lump ore can be directly charged into blast furnaces without high-temperature roasting,making it a more environmentally friendly and cleaner raw material option.The utilization of lump ore in blast furnace not only has obvious economic advantages but also achieves significant energy saving and carbon reduction effects.Therefore,an overview of the application of natural lump ore resources was provided,with a focus on its metallurgical properties and the factors influencing them.It further analyzed and summarized strategies for optimizing lump ore performance,particularly highlighting the advantages and technical challenges associated with preheating treatments.Additionally,the application experience,changes in technical and economic indicators,as well as the effects of energy saving and carbon reduction under the condition of a high ratio of lump ore in actual production were elaborated in detail.The results show that after loading lump ore to blast furnaces,the raw material cost is reduced by approximately 50.88 CNY/t,and the CO_(2)emissions from the production of 1 t pig iron can be reduced by 51.18 kg.
文摘Improving energy efficiency and lowering negative environmental impact through waste heat recovery(WHR)is a critical step toward sustainable cement manufacturing.This study analyzes advanced cogeneration systems for recovering waste heat from the Fallujah White Cement Plant in Iraq.The novelty of this work lies in its direct application and comparative thermodynamic analysis of three distinct cogeneration cycles—the Organic Rankine Cycle,the Single-Flash Steam Cycle,and the Dual-Pressure Steam Cycle—within the Iraqi cement industry,a context that has not been widely studied.The main objective is to evaluate and compare these models to determine the most effective approach for enhancing energy and exergy efficiencies.Themethodology involved detailed thermodynamic and exergy analyses of each system,supported by mathematical modelling and simulation using data from plant operations.The results reveal that the Dual-Pressure Steam Cycle emerged as the most effective system,delivering 13.76 MW of net power with a thermal efficiency of 32.8%and an exergy efficiency of 51%.This significantly outperformed the baseline Organic Rankine Cycle(8.18MW,18.8%thermal efficiency,30.7%exergy efficiency).These findings confirm that multipressure steam cycles offer a robust and practical solution for the Fallujah plant.This application provides a clear,high-impact pathway to enhance national industrial energy efficiency,significantly reduce CO_(2) emissions,and promote clean energy sustainability in Iraq.Future work should consider economic feasibility and potential integration with renewable energy sources to further enhance sustainability.
文摘为了探究玻璃成型预加热段中部凹陷的形成机理及玻璃厚度、长宽比两种形状参数对其影响,基于生产线预加热炉的工艺流程,建立了流体-热场-固体多物理场耦合数值模型.同时,利用高温红外热成像技术获取预加热段结束时玻璃表面的温度场分布情况,以验证炉腔内流体-热场耦合数值模型的准确性.然后基于流体-热场-固体多物理场模型对预加热段玻璃中部凹陷形成过程进行仿真,探究玻璃中部凹陷形成的机理.最后探讨了两种形状参数对玻璃凹陷变形的影响程度.研究表明:玻璃的形状参数对玻璃的形变有重要影响,即随玻璃厚度减小,弯曲刚度也不断减小,玻璃中部凹陷越严重;玻璃的长宽比对玻璃变形也有重要影响,当玻璃长宽比从6.32减小到1.58时,玻璃的横向热应变区会增大,玻璃的凹陷深度从4.65 mm增加到9.34 mm.
