Cyclic total reflux(CTR) batch distillation is a promising mode of the process but lacking of appropriate modeling for the period of filling the reflux drum.A new dynamic modeling method for the simulation of CTR batc...Cyclic total reflux(CTR) batch distillation is a promising mode of the process but lacking of appropriate modeling for the period of filling the reflux drum.A new dynamic modeling method for the simulation of CTR batch distillation is proposed in this work,in which the changes in column holdup and liquid flow rate during the filling of the drum,and the consequent change in valid number of theoretical plates are considered.The effect of drum holdup on operation time is investigated and the optimal drum holdup is obtained from the simulation.The dynamic modeling is compared to the conventional modeling without consideration of change in liquid flow rate. The experimental result shows that the present modeling is more reliable and more accurate,especially for the column with large liquid holdup.展开更多
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
Influenced by the seasonally reversed monsoons, water exchange through straits, and topography, the shelf and slope circulation in the northern South China Sea(NSCS) is complex and changeable. The typical current syst...Influenced by the seasonally reversed monsoons, water exchange through straits, and topography, the shelf and slope circulation in the northern South China Sea(NSCS) is complex and changeable. The typical current system in the NSCS consists of the slope current, South China Sea warm current(SCSWC), coastal current, and associated upwelling(in summer) and downwelling(in winter). This paper reviews recent advances in the study of NSCS shelf and slope circulation since the 1990 s,and summarizes the roles of Kuroshio intrusion, the monsoons, topography, and the buoyancy effect of the Pearl River plume in the shelf and slope current system of the NSCS. We also point out some potential scientific issues that require further study, such as the dynamic connection between the internal basin and shelf areas of the NSCS, the persistence of the SCSWC in winter, the temporo-spatial characteristics of downwelling during winter in the NSCS, and its material and energy transport.展开更多
文摘Cyclic total reflux(CTR) batch distillation is a promising mode of the process but lacking of appropriate modeling for the period of filling the reflux drum.A new dynamic modeling method for the simulation of CTR batch distillation is proposed in this work,in which the changes in column holdup and liquid flow rate during the filling of the drum,and the consequent change in valid number of theoretical plates are considered.The effect of drum holdup on operation time is investigated and the optimal drum holdup is obtained from the simulation.The dynamic modeling is compared to the conventional modeling without consideration of change in liquid flow rate. The experimental result shows that the present modeling is more reliable and more accurate,especially for the column with large liquid holdup.
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 Frontier Science Research Project of Chinese Academy of Sciences (Grant No. QYZDJ-SSW-DQC022)the National Natural Science Foundation of China (Grant Nos. 41476012, 41406038 & 41576003)the Natural Science Foundation of Guangdong Province (Grant No. 2014A030313777)
文摘Influenced by the seasonally reversed monsoons, water exchange through straits, and topography, the shelf and slope circulation in the northern South China Sea(NSCS) is complex and changeable. The typical current system in the NSCS consists of the slope current, South China Sea warm current(SCSWC), coastal current, and associated upwelling(in summer) and downwelling(in winter). This paper reviews recent advances in the study of NSCS shelf and slope circulation since the 1990 s,and summarizes the roles of Kuroshio intrusion, the monsoons, topography, and the buoyancy effect of the Pearl River plume in the shelf and slope current system of the NSCS. We also point out some potential scientific issues that require further study, such as the dynamic connection between the internal basin and shelf areas of the NSCS, the persistence of the SCSWC in winter, the temporo-spatial characteristics of downwelling during winter in the NSCS, and its material and energy transport.
