A new cooling technique based on thermal driving in high centrifugal field （TDHCF） is developed for gas turbine rotational components, such as turbine blades. The key point of TDHCF is to enhance heat transfer by th...A new cooling technique based on thermal driving in high centrifugal field （TDHCF） is developed for gas turbine rotational components, such as turbine blades. The key point of TDHCF is to enhance heat transfer by the fluid thermal driving in closed loop small channels placed in the high centrifugal field. Heat transfer characteristics of the new cooling technique are analyzed. In experiments, two different fluids （liquid water and Freon R12） are used as thermal driving media （fluid inside the loop channel）. And the channel width d is 1 mm and the height h is 30 mm. The temperature is measured by thermocouples and an average heat transfer coefficient KH is defined to indicate heat transfer capacity of TDHCF. Experimental results show that KH is enhanced when heat flux and the rotating speed increase. And thermal properties of thermal driving media are also influenced by KH. Larger KH can be achieved by using Freon R12 as thermal driving medium compared with using liquid water. It can increase to 2 300 W/（m^2 · K） and it is much higher than that of the normal air cooling method （usually at the level of 600-1200 W/（m^2·K））. All fundamental studies of TDHCF show that there actually exists thermal driving in the closed loop small channel in the centrifugal field to improve heat transfer characteristics.展开更多
Of all reported polymorphs of clopidogrel hydrogen sulfate, Form Ⅰ is difficult to produce and store owing to its poor thermostability. It is reported that Form Ⅰ can spontaneously transform into Form Ⅱ at high tem...Of all reported polymorphs of clopidogrel hydrogen sulfate, Form Ⅰ is difficult to produce and store owing to its poor thermostability. It is reported that Form Ⅰ can spontaneously transform into Form Ⅱ at high temperature and humidity. In this study, high purity Form I of clopidogrel hydrogen sulfate with good thermodynamic stability was prepared by a centrifugation-assisted recrystallization technology. The resultant product was characterized by powder X-ray diffraction （PXRD）, differential scanning calorimetry （DSC） and scanning electron microscope （SEM）. The results showed that the crystallinity and crystallite size of the Form Ⅰ prepared by the centrifugation-assisted recrystallization method were larger than those obtained by conventional anti-solvent recrystallization methods. Long-term thermostability testing demonstrated that the improved product can keep stable crystal structure even at high temperature and humidity.展开更多
SnO2 hollow spheres have been synthesized via a facile hydrothermal method using sulfonated polystyrene beads as a template followed by a calcination process in air.X-ray diffraction,scanning electron microscopy,and t...SnO2 hollow spheres have been synthesized via a facile hydrothermal method using sulfonated polystyrene beads as a template followed by a calcination process in air.X-ray diffraction,scanning electron microscopy,and transmission electron microscopy show that the as-obtained SnO2 hollow spheres have a wall thickness of about 50 nm,and consist of nanosized SnO2 particles with a mean diameter of about 15 nm.Electrochemical measurements indicate that the SnO2 hollow spheres exhibit improved electrochemical performance in terms of specific capacity and rate capability in comparison with commercial SnO2 when used as anode materials for lithium-ion batteries.The enhanced performance may be attributed to the spherical and hollow structure,as well as the building blocks of SnO2 nanoparticles.展开更多
文摘A new cooling technique based on thermal driving in high centrifugal field （TDHCF） is developed for gas turbine rotational components, such as turbine blades. The key point of TDHCF is to enhance heat transfer by the fluid thermal driving in closed loop small channels placed in the high centrifugal field. Heat transfer characteristics of the new cooling technique are analyzed. In experiments, two different fluids （liquid water and Freon R12） are used as thermal driving media （fluid inside the loop channel）. And the channel width d is 1 mm and the height h is 30 mm. The temperature is measured by thermocouples and an average heat transfer coefficient KH is defined to indicate heat transfer capacity of TDHCF. Experimental results show that KH is enhanced when heat flux and the rotating speed increase. And thermal properties of thermal driving media are also influenced by KH. Larger KH can be achieved by using Freon R12 as thermal driving medium compared with using liquid water. It can increase to 2 300 W/（m^2 · K） and it is much higher than that of the normal air cooling method （usually at the level of 600-1200 W/（m^2·K））. All fundamental studies of TDHCF show that there actually exists thermal driving in the closed loop small channel in the centrifugal field to improve heat transfer characteristics.
基金National Natural Science Foundation of China(Grant No.51403188)Zhejiang Provincial Natural Science Foundation of China(Grant No.LY13E030004)Research Fund for the Doctoral Program of Higher Education of China(Grant No.20123318120005)
文摘Of all reported polymorphs of clopidogrel hydrogen sulfate, Form Ⅰ is difficult to produce and store owing to its poor thermostability. It is reported that Form Ⅰ can spontaneously transform into Form Ⅱ at high temperature and humidity. In this study, high purity Form I of clopidogrel hydrogen sulfate with good thermodynamic stability was prepared by a centrifugation-assisted recrystallization technology. The resultant product was characterized by powder X-ray diffraction （PXRD）, differential scanning calorimetry （DSC） and scanning electron microscope （SEM）. The results showed that the crystallinity and crystallite size of the Form Ⅰ prepared by the centrifugation-assisted recrystallization method were larger than those obtained by conventional anti-solvent recrystallization methods. Long-term thermostability testing demonstrated that the improved product can keep stable crystal structure even at high temperature and humidity.
基金supported by the National Natural Science Foundation of China (21121063)the National Key Project on Basic Research(2011CB935700 and 2009CB930400)the Chinese Academy of Sciences
文摘SnO2 hollow spheres have been synthesized via a facile hydrothermal method using sulfonated polystyrene beads as a template followed by a calcination process in air.X-ray diffraction,scanning electron microscopy,and transmission electron microscopy show that the as-obtained SnO2 hollow spheres have a wall thickness of about 50 nm,and consist of nanosized SnO2 particles with a mean diameter of about 15 nm.Electrochemical measurements indicate that the SnO2 hollow spheres exhibit improved electrochemical performance in terms of specific capacity and rate capability in comparison with commercial SnO2 when used as anode materials for lithium-ion batteries.The enhanced performance may be attributed to the spherical and hollow structure,as well as the building blocks of SnO2 nanoparticles.
