The current state-of-the-art in the development of cellular metal foams is reviewed, with focus on their fabrication, mechanical/thermal/acoustic properties, and potential applications as lightweight panels, energy ab...The current state-of-the-art in the development of cellular metal foams is reviewed, with focus on their fabrication, mechanical/thermal/acoustic properties, and potential applications as lightweight panels, energy absorbers, heat exchangers, and acoustic liners. Foam property charts with scaling relations are presented, allowing scoping and selection through the use of material indices.展开更多
Inspired by the property diagrams in thermodynamics,which distinctly reflect the performance and characteristics of thermodynamic cycles,we establish a state equation for heat motion and introduce a two-dimension prop...Inspired by the property diagrams in thermodynamics,which distinctly reflect the performance and characteristics of thermodynamic cycles,we establish a state equation for heat motion and introduce a two-dimension property diagram,T-q diagram,in heat transfer to analyze and optimize the performance of heat exchangers,where heat flow is a state parameter for heat motion.According to the property diagram,it is convenient to obtain the influences of heat exchanger area,heat capacity rate and flow arrangement on the heat transfer performance during the analysis of heat exchangers and their networks.For instance,when analyzing the heat exchanger network in a district heating system,it is obvious to find that:if both the heat demand and the indoor air temperature in each branch of the network are the same,the total area of heat exchangers,the flow rate of water and the return water temperature in each branch are all the same;if the indoor air temperatures in different branches are different,the temperatures of the waters after flowing through different branches are different,which means that the mixing process of return waters with the same temperature is not an essential requirement to realize the best performance of district heating systems.展开更多
To improve the photocatalytic performance of pristine photocatalysts,element doping,construction of composites and fabrication of novel nanostructures are recognized as universal modification methods.These methods hav...To improve the photocatalytic performance of pristine photocatalysts,element doping,construction of composites and fabrication of novel nanostructures are recognized as universal modification methods.These methods have been experimentally verified to be effective in manifold photocatalytic application over various photocatalysts.Density functional theory(DFT)calculation is a powerful and fundamental tool to pinpoint the intrinsic mechanism of the enhanced photocatalytic activity.And it holds the degree of precision ranging from atoms,molecules to unit cells.Herein,recent DFT calculation research progress of modified s-triazine-based graphitic carbon nitride(g-C3N4)systems as photocatalysts is summarized.To specify,we collected information of doping site,formation energy,geometric,and electronic properties.We also discussed the synergistic effect of work function,Fermi level and band edge position on the built-in electric field,transfer route of photogenerated charge carriers and photocatalytic mechanism(traditional typeⅡor direct Z-scheme heterostructure).Moreover,we analyzed the geometric configuration,band structure,and stability of g-C3N4 nanocluster,nanoribbon,and nanotube.Finally,future perspective in the further theoretical revelation of g-C3N4-based photocatalysts is proposed.展开更多
基金funds of the U.K. Engineering and Physical Sciences Research Council，partly by the U.S. Office of Naval Research ONR/ONRIFO，ONR of USA，国家自然科学基金
文摘The current state-of-the-art in the development of cellular metal foams is reviewed, with focus on their fabrication, mechanical/thermal/acoustic properties, and potential applications as lightweight panels, energy absorbers, heat exchangers, and acoustic liners. Foam property charts with scaling relations are presented, allowing scoping and selection through the use of material indices.
基金supported by the National Natural Science Foundation of China(51006060 and 51036003)the Foundation for the Author of National Excellent Doctoral Dissertation of China
文摘Inspired by the property diagrams in thermodynamics,which distinctly reflect the performance and characteristics of thermodynamic cycles,we establish a state equation for heat motion and introduce a two-dimension property diagram,T-q diagram,in heat transfer to analyze and optimize the performance of heat exchangers,where heat flow is a state parameter for heat motion.According to the property diagram,it is convenient to obtain the influences of heat exchanger area,heat capacity rate and flow arrangement on the heat transfer performance during the analysis of heat exchangers and their networks.For instance,when analyzing the heat exchanger network in a district heating system,it is obvious to find that:if both the heat demand and the indoor air temperature in each branch of the network are the same,the total area of heat exchangers,the flow rate of water and the return water temperature in each branch are all the same;if the indoor air temperatures in different branches are different,the temperatures of the waters after flowing through different branches are different,which means that the mixing process of return waters with the same temperature is not an essential requirement to realize the best performance of district heating systems.
基金This work was supported by NSFC(U1705251,21573170,21905219,and 21433007)National Postdoctoral Program for Innovative Talents(BX20180231)+2 种基金Fundamental Research Funds for the Central Universities(WUT:2018IVA089)Innovative Research Funds of SKLWUT(2017-ZD-4)Opening Project of Key Laboratory of Optoelectronic Chemical Materials and Devices,Ministry of Education,Jianghan University(JDGD-201704).
文摘To improve the photocatalytic performance of pristine photocatalysts,element doping,construction of composites and fabrication of novel nanostructures are recognized as universal modification methods.These methods have been experimentally verified to be effective in manifold photocatalytic application over various photocatalysts.Density functional theory(DFT)calculation is a powerful and fundamental tool to pinpoint the intrinsic mechanism of the enhanced photocatalytic activity.And it holds the degree of precision ranging from atoms,molecules to unit cells.Herein,recent DFT calculation research progress of modified s-triazine-based graphitic carbon nitride(g-C3N4)systems as photocatalysts is summarized.To specify,we collected information of doping site,formation energy,geometric,and electronic properties.We also discussed the synergistic effect of work function,Fermi level and band edge position on the built-in electric field,transfer route of photogenerated charge carriers and photocatalytic mechanism(traditional typeⅡor direct Z-scheme heterostructure).Moreover,we analyzed the geometric configuration,band structure,and stability of g-C3N4 nanocluster,nanoribbon,and nanotube.Finally,future perspective in the further theoretical revelation of g-C3N4-based photocatalysts is proposed.
