Nano fluid is considered to be a class of high efficient heat transfer fluid created by dispersing some special solid nanoparticles (normally less than 100 nm) in traditional heat transfer fluid. The present experimen...Nano fluid is considered to be a class of high efficient heat transfer fluid created by dispersing some special solid nanoparticles (normally less than 100 nm) in traditional heat transfer fluid. The present experiment was conducted aiming at investigating the forced heat transfer characteristics of aqueous copper (Cu) nanofluid at varying concentration of Cu nano-particles in different flow regimes (300<Re≤16 000). The forced convective heat transfer enhancement is available both in the laminar and turbulent flow with increasing the concentration. Especially, the enhancement rate increases dramatically in laminar flow regime, for instance, the heat transfer coefficient of Cu/water nanofluid increases by two times at around Re=2 000 compared with that of base fluid water, and averagely increases by 62% at 1% volume fraction. However, the heat transfer coefficient of Cu/water decreases sharply in the transition flow regime. Furthermore, it has the trend that the heat transfer coefficient displays worse with increasing the concentration.展开更多
Spacing characteristics of Langmuir circulation （LC） arc computed by large eddy simulation （LES） model under modest wind. LC is an organized vertical motion, evidenced as buoyant materials forming lines nearly par...Spacing characteristics of Langmuir circulation （LC） arc computed by large eddy simulation （LES） model under modest wind. LC is an organized vertical motion, evidenced as buoyant materials forming lines nearly parallel to the wind direction. The horizontal distribution of velocity computed by LES shows clear lines formed by LC. These lines grow and parallel to each other for a while, which we call the stable state, before they finally form Y-junctions. We computed spacing between every two parallel lines by averaging them under the stable state. Statistically, spacing results of 154 tests （seven wind speed cases of 22 test runs each） show high correlations between spacing and wind speed, as well as mixed layer depth. The relationship of spacing and wind is important for future LC parameterization of upper-ocean mixing.展开更多
To increase the service life of rechargeable batteries,transition metal oxide hosts with high structural stability for the intercalation of carrier ions are important.Herein,we reconstruct the crystal structure of a c...To increase the service life of rechargeable batteries,transition metal oxide hosts with high structural stability for the intercalation of carrier ions are important.Herein,we reconstruct the crystal structure of a commercial V_(2)O_(5)by pre-intercalating H^(+)and H_(2)O pillars using a facile hydrothermal reaction and obtain a bi-layer structured H_(0.642)V_(2)O_(5)·0.143H_(2)O(HVO)as an excellent host for aqueous Zn-ion batteries.Benefiting from the structural reconstruction,the irreversible“layer-to-amorphous”phase evolution during cycling is considerably less,resulting in ultra-high cycling stability of HVO with nearly no capacity fading even after 500 cycles at a current density of 0.5Ag^(-1).Moreover,a synthetic proton and Zn^(2+)intercalation mechanism in the HVO host is demonstrated.This work provides both a facile synthesis method for the preparation of V-based compounds and a new viewpoint for achieving high-performance host materials.展开更多
基金supported by Basic Science Research Program through the National Research Foundation of Korea (NRF)funded by the Ministry of Education, Science and Technology (No.2012-0004544)
文摘Nano fluid is considered to be a class of high efficient heat transfer fluid created by dispersing some special solid nanoparticles (normally less than 100 nm) in traditional heat transfer fluid. The present experiment was conducted aiming at investigating the forced heat transfer characteristics of aqueous copper (Cu) nanofluid at varying concentration of Cu nano-particles in different flow regimes (300<Re≤16 000). The forced convective heat transfer enhancement is available both in the laminar and turbulent flow with increasing the concentration. Especially, the enhancement rate increases dramatically in laminar flow regime, for instance, the heat transfer coefficient of Cu/water nanofluid increases by two times at around Re=2 000 compared with that of base fluid water, and averagely increases by 62% at 1% volume fraction. However, the heat transfer coefficient of Cu/water decreases sharply in the transition flow regime. Furthermore, it has the trend that the heat transfer coefficient displays worse with increasing the concentration.
基金Supported by the National Natural Science Foundation of China(Nos.40876012,41176016)the Open Research Foundation for the State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of Oceanography,State Oceanic Administration (No.SOED1210)the National Natural Science Foundation of China for Creative Research Groups (No.41121064)
文摘Spacing characteristics of Langmuir circulation （LC） arc computed by large eddy simulation （LES） model under modest wind. LC is an organized vertical motion, evidenced as buoyant materials forming lines nearly parallel to the wind direction. The horizontal distribution of velocity computed by LES shows clear lines formed by LC. These lines grow and parallel to each other for a while, which we call the stable state, before they finally form Y-junctions. We computed spacing between every two parallel lines by averaging them under the stable state. Statistically, spacing results of 154 tests （seven wind speed cases of 22 test runs each） show high correlations between spacing and wind speed, as well as mixed layer depth. The relationship of spacing and wind is important for future LC parameterization of upper-ocean mixing.
基金supported by the Basic and Applied Basic Research Foundation of Guangdong Province(2019A1515110094).
文摘To increase the service life of rechargeable batteries,transition metal oxide hosts with high structural stability for the intercalation of carrier ions are important.Herein,we reconstruct the crystal structure of a commercial V_(2)O_(5)by pre-intercalating H^(+)and H_(2)O pillars using a facile hydrothermal reaction and obtain a bi-layer structured H_(0.642)V_(2)O_(5)·0.143H_(2)O(HVO)as an excellent host for aqueous Zn-ion batteries.Benefiting from the structural reconstruction,the irreversible“layer-to-amorphous”phase evolution during cycling is considerably less,resulting in ultra-high cycling stability of HVO with nearly no capacity fading even after 500 cycles at a current density of 0.5Ag^(-1).Moreover,a synthetic proton and Zn^(2+)intercalation mechanism in the HVO host is demonstrated.This work provides both a facile synthesis method for the preparation of V-based compounds and a new viewpoint for achieving high-performance host materials.
