In the feeding process of aluminum electrolytic, feeding quantity of alumina affects eventually dissolved quantity at the end of a feeding cycle. Based on the OpenFOAM platform, dissolution model coupled with heat and...In the feeding process of aluminum electrolytic, feeding quantity of alumina affects eventually dissolved quantity at the end of a feeding cycle. Based on the OpenFOAM platform, dissolution model coupled with heat and mass transfer was established. Applying the Rosin-Rammler function, alumina particle size distribution under different feeding quantities was obtained. The temperature response of electrolyte after feeding was included and calculated, and the dissolution processes of alumina with different feeding quantities (0.6, 0.8, 1.0, 1.2, 1.4, 1.6 kg) after feeding were simulated in 300 kA aluminum reduction cell. The results show that with the increase of feeding quantity, accumulated mass fraction of dissolved alumina decreases, and the time required for the rapid dissolution stage extends. When the feeding quantity is 0.6 kg and 1.2 kg, it takes the shortest time for the electrolyte temperature dropping before rebounding back. With the increase of feeding quantity, the dissolution rate in the rapid dissolution stage increases at first and then decreases gradually. The most suitable feeding quantity is 1.2 kg. The fitting equation of alumina dissolution curve under different feeding quantities is obtained, which can be used to evaluate the alumina dissolution and guide the feeding quantity and feeding cycle.展开更多
Based on the coexistence of the Blandford-Znajek and magnetic coupling processes in black hole （BH） accretion disc, a multi-parameter model for jet powers and radio loudnees of active galactic nuclei （AGNs） is stu...Based on the coexistence of the Blandford-Znajek and magnetic coupling processes in black hole （BH） accretion disc, a multi-parameter model for jet powers and radio loudnees of active galactic nuclei （AGNs） is studied. It turns out that radio-loudnees of AGNs couM be governed by five parameters： （i） the BH spin, （ii） a power-law index of the variation of the magnetic field on the disc; （iii） a parameter determining the position of the inner edge of the disc, （iv） the ratio of the pressure of the magnetic field on the horizon to the ram pressure of the innermost parts of an accretion flow, and （v） the ratio of the angular velocity of the open field lines to that of the horizon. The observed dichotomy between radio-loud and radio-quiet AGNs is well interpreted by the effects of the above parameters. Furthermore, we discuss the derivative of radio loudness of AGNs with respect to each parameter separately. In addition, the effect of the screw instability on radio loudness of AGNs is discussed.展开更多
基金Project(2010AA065201) supported by the High-Tech Research and Development Program of ChinaProject(2018zzts157) supported by the Fundamental Research Funds for the Central Universities,China
文摘In the feeding process of aluminum electrolytic, feeding quantity of alumina affects eventually dissolved quantity at the end of a feeding cycle. Based on the OpenFOAM platform, dissolution model coupled with heat and mass transfer was established. Applying the Rosin-Rammler function, alumina particle size distribution under different feeding quantities was obtained. The temperature response of electrolyte after feeding was included and calculated, and the dissolution processes of alumina with different feeding quantities (0.6, 0.8, 1.0, 1.2, 1.4, 1.6 kg) after feeding were simulated in 300 kA aluminum reduction cell. The results show that with the increase of feeding quantity, accumulated mass fraction of dissolved alumina decreases, and the time required for the rapid dissolution stage extends. When the feeding quantity is 0.6 kg and 1.2 kg, it takes the shortest time for the electrolyte temperature dropping before rebounding back. With the increase of feeding quantity, the dissolution rate in the rapid dissolution stage increases at first and then decreases gradually. The most suitable feeding quantity is 1.2 kg. The fitting equation of alumina dissolution curve under different feeding quantities is obtained, which can be used to evaluate the alumina dissolution and guide the feeding quantity and feeding cycle.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10173004, 10373006, and 10121503
文摘Based on the coexistence of the Blandford-Znajek and magnetic coupling processes in black hole （BH） accretion disc, a multi-parameter model for jet powers and radio loudnees of active galactic nuclei （AGNs） is studied. It turns out that radio-loudnees of AGNs couM be governed by five parameters： （i） the BH spin, （ii） a power-law index of the variation of the magnetic field on the disc; （iii） a parameter determining the position of the inner edge of the disc, （iv） the ratio of the pressure of the magnetic field on the horizon to the ram pressure of the innermost parts of an accretion flow, and （v） the ratio of the angular velocity of the open field lines to that of the horizon. The observed dichotomy between radio-loud and radio-quiet AGNs is well interpreted by the effects of the above parameters. Furthermore, we discuss the derivative of radio loudness of AGNs with respect to each parameter separately. In addition, the effect of the screw instability on radio loudness of AGNs is discussed.
