The feasibility study of the AlCl(g) generated by Al_2O-AlCl_2-C system under vacuum was carried out by thermodynamic analysis and CASTEP package of the Material Studio program which was based on density functional th...The feasibility study of the AlCl(g) generated by Al_2O-AlCl_2-C system under vacuum was carried out by thermodynamic analysis and CASTEP package of the Material Studio program which was based on density functional theory(DFT) formalism. Thermodynamic calculations indicate that Al Cl and CO molecules can be formed under conditions of temperature 1760 K and the pressure of 60 Pa. The interaction of Al_2O and AlCl_2 with C shows that the chemical adsorption of Al_2O and AlCl_2 does take place on C(001) crystal plane, and at the same time, new chemical bond is formed between Al atom in Al_2O and Cl atoms from one of the Al—Cl bonds in AlCl_2. The results, after 1.25 ps dynamics simulation, indicate that adsorbed Al Cl molecules are generated and CO molecule will be formed in this system, and they will escape from C(001) surface after a longer period of dynamic simulation time. It means that the reaction of Al_2O and AlCl_2 with C can be carried out under given constraint condition.展开更多
Improving the energy conversion efficiency in metallic fuel(e.g.,Al)combustion is always desirable but challenging,which often involves redox reactions of aluminum(Al)with various mixed oxidizing environments.For inst...Improving the energy conversion efficiency in metallic fuel(e.g.,Al)combustion is always desirable but challenging,which often involves redox reactions of aluminum(Al)with various mixed oxidizing environments.For instance,Al-O reaction is the most common pathway to release limited energy while Al-F reaction has received much attentions to enhance Al combustion efficiency.However,microscopic understanding of the Al-O/Al-F reaction dynamics remains unsolved,which is fundamentally necessary to further improve Al combustion efficiency.In this work,for the first time,Al-O/Al-F reaction dynamic effects on the combustion of aluminum nanoparticles(n-Al)in oxygen/fluorine containing environments have been revealed via reactive molecular dynamics(RMD)simulations meshing together combustion experiments.Three RMD simulation systems of Al core/O_(2)/HF,n-Al/O_(2)/HF,and n-Al/O_(2)/CF4 with oxygen percentage ranging from 0%to 100%have been performed.The n-Al combustion in mixed O_(2)/CF_4 environments have been conducted by constant volume combustion experiments.RMD results show that Al-O reaction exhibits kinetic benefits while Al-F reaction owns thermodynamic benefits for n-Al combustion.In n-Al/O_(2)/HF,Al-O reaction gives faster energy release rate than Al-F reaction(1.1 times).The optimal energy release efficiency can be achieved with suitable oxygen percentage of 10%and 50%for n-Al/O_(2)/HF and n-Al/O_(2)/CF_4,respectively.In combustion experiments,90%of oxygen percentage can optimally enhance the peak pressure,pressurization rate and combustion heat.Importantly,Al-O reaction prefers to occur on the surface regions while Al-F reaction prefers to proceed in the interior regions of n-Al,confirming the kinetic/thermodynamic benefits of Al-O/Al-F reactions.The synergistic effect of Al-O/Al-F reaction for greatly enhancing n-Al combustion efficiency is demonstrated at atomicscale,which is beneficial for optimizing the combustion performance of metallic fuel.展开更多
基金Projects(51104078,51264023)supported by the National Natural Science Foundation of ChinaProject(2010CD022)supported by Yunnan Province Applied Basic Research Fund,China+2 种基金Project(IRT1250)supported by the Program for Innovative Research Team in University of Ministry of Education of ChinaProject(U1202271)supported by the National Natural Science Foundation of China-Yunnan United FundProject(KKZ3201252020)supported by Kunming University of Science and Technology for Talent Training,China
文摘The feasibility study of the AlCl(g) generated by Al_2O-AlCl_2-C system under vacuum was carried out by thermodynamic analysis and CASTEP package of the Material Studio program which was based on density functional theory(DFT) formalism. Thermodynamic calculations indicate that Al Cl and CO molecules can be formed under conditions of temperature 1760 K and the pressure of 60 Pa. The interaction of Al_2O and AlCl_2 with C shows that the chemical adsorption of Al_2O and AlCl_2 does take place on C(001) crystal plane, and at the same time, new chemical bond is formed between Al atom in Al_2O and Cl atoms from one of the Al—Cl bonds in AlCl_2. The results, after 1.25 ps dynamics simulation, indicate that adsorbed Al Cl molecules are generated and CO molecule will be formed in this system, and they will escape from C(001) surface after a longer period of dynamic simulation time. It means that the reaction of Al_2O and AlCl_2 with C can be carried out under given constraint condition.
基金support by the National Natural Science Foundation of China(NSFC,Grant Nos.12002324,12372341,12172342)。
文摘Improving the energy conversion efficiency in metallic fuel(e.g.,Al)combustion is always desirable but challenging,which often involves redox reactions of aluminum(Al)with various mixed oxidizing environments.For instance,Al-O reaction is the most common pathway to release limited energy while Al-F reaction has received much attentions to enhance Al combustion efficiency.However,microscopic understanding of the Al-O/Al-F reaction dynamics remains unsolved,which is fundamentally necessary to further improve Al combustion efficiency.In this work,for the first time,Al-O/Al-F reaction dynamic effects on the combustion of aluminum nanoparticles(n-Al)in oxygen/fluorine containing environments have been revealed via reactive molecular dynamics(RMD)simulations meshing together combustion experiments.Three RMD simulation systems of Al core/O_(2)/HF,n-Al/O_(2)/HF,and n-Al/O_(2)/CF4 with oxygen percentage ranging from 0%to 100%have been performed.The n-Al combustion in mixed O_(2)/CF_4 environments have been conducted by constant volume combustion experiments.RMD results show that Al-O reaction exhibits kinetic benefits while Al-F reaction owns thermodynamic benefits for n-Al combustion.In n-Al/O_(2)/HF,Al-O reaction gives faster energy release rate than Al-F reaction(1.1 times).The optimal energy release efficiency can be achieved with suitable oxygen percentage of 10%and 50%for n-Al/O_(2)/HF and n-Al/O_(2)/CF_4,respectively.In combustion experiments,90%of oxygen percentage can optimally enhance the peak pressure,pressurization rate and combustion heat.Importantly,Al-O reaction prefers to occur on the surface regions while Al-F reaction prefers to proceed in the interior regions of n-Al,confirming the kinetic/thermodynamic benefits of Al-O/Al-F reactions.The synergistic effect of Al-O/Al-F reaction for greatly enhancing n-Al combustion efficiency is demonstrated at atomicscale,which is beneficial for optimizing the combustion performance of metallic fuel.
