火焰在混合燃气中的传播受到很多因素的影响,研究燃气射流的点火特性对深入了解燃烧稳定性机理具有重要意义。采用实验的方法研究了天然气/氢气射流扩散碰撞火焰在喷嘴出口位置点火的点火特性,对射流扩散火焰的点火过程进行了流场可视...火焰在混合燃气中的传播受到很多因素的影响,研究燃气射流的点火特性对深入了解燃烧稳定性机理具有重要意义。采用实验的方法研究了天然气/氢气射流扩散碰撞火焰在喷嘴出口位置点火的点火特性,对射流扩散火焰的点火过程进行了流场可视化研究和定量分析。实验同时采用2台高速摄像仪,采集了点火过程中的高速彩色图像和纹影图像。通过基于颜色分析的图像处理方法,对点火过程中的蓝色和红黄色火焰强度随时间的变化进行了定量化分析。对高速纹影图像采用光流算法,获得了点火过程中包含火焰和气体的整个流场的速度特性。实验发现:经数字化火焰颜色识别(digital flame color discrimination,DFCD)将图像增强后的高速彩色图像可以完整显示火焰的发展过程;点火初期由于可燃气与空气的混合作用,火焰前锋面呈现蓝色;随后蓝色火焰逐渐消失,红黄色扩散火焰逐渐发展。速度计算结果显示,点火过程火焰前锋绝对速度先逐渐下降,在火焰传播至平板后迅速增大,至平板边缘后重新下降。碰撞壁面对甲烷/氢气射流流场的改变一定程度上影响了点火时火焰的传播特性。速度结果能够展示完整流场的速度变化,该方法可有效用于复杂湍流结构下火焰和流场的研究。展开更多
It is well established that hydrogen has the potential to make a significant contribution to the world energy production.In U.S.,majority of hydrogen production plants implement steam methane reforming(SMR) for centra...It is well established that hydrogen has the potential to make a significant contribution to the world energy production.In U.S.,majority of hydrogen production plants implement steam methane reforming(SMR) for centralized hydrogen production.However,there is a wide lack of agreement on the nascent stage of using hydrogen as fuel in vehicles industry because of the difficulty in delivery and storage.By performing technological and economic analysis,this work aims to establish the most feasible hydrogen production pathway for automotives in near future.From the evaluation,processes such as thermal cracking of ammonia and centralized hydrogen production followed by bulk delivery are eliminated while on-site steam reforming of methanol and natural gas are the most technologically feasible options.These two processes are further evaluated by comprehensive economic analysis.The results showed that the steam reforming(SR) of natural gas has a shorter payback time and a higher return on investment(ROI) and internal rate of return(IRR).Sensitivity analysis has also been constructed to evaluate the impact of variables like NG feedstock price,capital of investment and operating capacity factor on the overall production cost of hydrogen.Based on this study,natural gas is prompted to be the most economically and technologically available raw material for short-term hydrogen production before the transition to renewable energy source such as solar energy,biomass and wind power.展开更多
文摘火焰在混合燃气中的传播受到很多因素的影响,研究燃气射流的点火特性对深入了解燃烧稳定性机理具有重要意义。采用实验的方法研究了天然气/氢气射流扩散碰撞火焰在喷嘴出口位置点火的点火特性,对射流扩散火焰的点火过程进行了流场可视化研究和定量分析。实验同时采用2台高速摄像仪,采集了点火过程中的高速彩色图像和纹影图像。通过基于颜色分析的图像处理方法,对点火过程中的蓝色和红黄色火焰强度随时间的变化进行了定量化分析。对高速纹影图像采用光流算法,获得了点火过程中包含火焰和气体的整个流场的速度特性。实验发现:经数字化火焰颜色识别(digital flame color discrimination,DFCD)将图像增强后的高速彩色图像可以完整显示火焰的发展过程;点火初期由于可燃气与空气的混合作用,火焰前锋面呈现蓝色;随后蓝色火焰逐渐消失,红黄色扩散火焰逐渐发展。速度计算结果显示,点火过程火焰前锋绝对速度先逐渐下降,在火焰传播至平板后迅速增大,至平板边缘后重新下降。碰撞壁面对甲烷/氢气射流流场的改变一定程度上影响了点火时火焰的传播特性。速度结果能够展示完整流场的速度变化,该方法可有效用于复杂湍流结构下火焰和流场的研究。
基金Supported by the National Natural Science Foundation of China(61873323,61773174,61573162)the Wuhan Science and Technology Plan Project(2018010401011292)+2 种基金the Hubei Province Natural and Science Foundation(2017CFB4165,2016CFA037)the Open Fund Project of Hubei Province Key Laboratory of Intelligent Information Processing and Real-time Industrial System(znxx2018ZD02)the Basic Research Project of Shenzhen(JCYJ20170307160923202,JCYJ20170818163921328)
基金support from the Hong Kong University of Science and Technology via the Undergraduate Research Opportunity Program (UROP)Lighten R&D Consultancy Ltd for providing advices
文摘It is well established that hydrogen has the potential to make a significant contribution to the world energy production.In U.S.,majority of hydrogen production plants implement steam methane reforming(SMR) for centralized hydrogen production.However,there is a wide lack of agreement on the nascent stage of using hydrogen as fuel in vehicles industry because of the difficulty in delivery and storage.By performing technological and economic analysis,this work aims to establish the most feasible hydrogen production pathway for automotives in near future.From the evaluation,processes such as thermal cracking of ammonia and centralized hydrogen production followed by bulk delivery are eliminated while on-site steam reforming of methanol and natural gas are the most technologically feasible options.These two processes are further evaluated by comprehensive economic analysis.The results showed that the steam reforming(SR) of natural gas has a shorter payback time and a higher return on investment(ROI) and internal rate of return(IRR).Sensitivity analysis has also been constructed to evaluate the impact of variables like NG feedstock price,capital of investment and operating capacity factor on the overall production cost of hydrogen.Based on this study,natural gas is prompted to be the most economically and technologically available raw material for short-term hydrogen production before the transition to renewable energy source such as solar energy,biomass and wind power.
