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Hydrodynamic Investigation of Tapered-in Fluidization and Comparison with Tapered-out Fluidized Beds and Cylindrical Fluidized Beds
, M.Sc. Thesis Sharif University of Technology ; Molaei, Asghar (Supervisor)
Abstract
Tapered-in fluidized beds, have unique dynamic characteristics compared to cylindrical fluidized beds, because of the velocity gradient in the axial direction. Therefore in the recent years, tapered fluidized beds were widely used in various processes such as biochemical reactions, biological, crystallization, gasification, liquefaction, etc. In this study, a two-dimensional gas-solid model using Eulerian-Eulerian approach along with the kinetic theory of granular solid in a tapered-in fluidized bed was applied. Moreover, the tapered-in fluidized beds were compared with the tapered-out fluidized beds and cylindrical fluidized beds in order to investigate the hydrodynamic behavior of the...
Effect of step geometry on the performance of the airlift pump
, Article International Journal of Fluid Mechanics Research ; Volume 38, Issue 5 , 2011 , Pages 387-408 ; 10642277 (ISSN) ; Karimi, A ; Saidi, M. H ; Sharif University of Technology
2011
Abstract
Airlift pumps are devices which are widely used in industrial applications. Parameters such as diameter of the pipe, tapering angle of the upriser pipe, submergence ratio, the gas flow rate, bubble diameter, and inlet gas pressure affect the performance of this type of pumps. In this research, the performances of airlift pumps with a vertical upriser length of 914 mm and initial diameters of 6 and 8 mm and various heights for steps, range 0:2 to 0:9 m, in submergence ratio of 0:6 are investigated numerically. The results show the improvement in the performance of step airlift pump (SALP) in comparison with ordinary type (OALP). Considering the effect of height of steps and secondary pipe...
Novel phenomenological discrete bubble model of freely bubbling dense gas-solid fluidized beds: Application to two-dimensional beds
, Article AIChE Journal ; Volume 58, Issue 11 , January , 2012 , Pages 3306-3317 ; 00011541 (ISSN) ; Molaei Dehkordi, A ; Deen, N. G ; van Sint Annaland, M ; Kuipers, J. A. M ; Sharif University of Technology
2012
Abstract
A phenomenological discrete bubble model has been developed for freely bubbling dense gas-solid fluidized beds and validated for a pseudo-two-dimensional fluidized bed. In this model, bubbles are treated as distinct elements and their trajectories are tracked by integrating Newton's equation of motion. The effect of bubble-bubble interactions was taken into account via a modification of the bubble velocity. The emulsion phase velocity was obtained as a superposition of the motion induced by individual bubbles, taking into account bubble-bubble interaction. This novel model predicts the bubble size evolution and the pattern of emulsion phase circulation satisfactorily. Moreover, the effects...
Effect of bubble size and angle of tapering upriser pipe on the performance of airlift pumps
, Article Particulate Science and Technology ; Volume 28, Issue 4 , Aug , 2010 , Pages 332-347 ; 02726351 (ISSN) ; Saidi, M. H ; Karimi, A ; Zamiri, A ; Sharif University of Technology
2010
Abstract
Airlift pumps are devices with the ability to lift liquid phase by injecting the gas phase. Parameters that affect the performance of these pumps are divided into two groups. The first group contains design parameters such as diameter of the pipe, tapering angle of the upriser pipe, and the submergence ratio, which is the ratio of immersed length to the total length of the upriser. The second group includes operating parameters such as the gas flow rate, bubble diameter, bubble distribution, and inlet gas pressure. In this research, the performance of an airlift pump is investigated numerically for different submergence ratios and different diameter of the upriser pipe. For this purpose, an...
Effect of bubble size and angle of tapered upriser pipe on the effectiveness of a two phase lifting pump
, Article 2009 ASME Fluids Engineering Division Summer Conference, 2nd August 2009 through 6 August 2009 ; Volume 1, Issue PART B , 2009 , Pages 807-814 ; 9780791843727 (ISBN) ; Saidi, M. H ; Zamiri, A ; Karimi, A ; Sharif University of Technology
2009
Abstract
Two phase lifting pumps are devices with the ability of lifting liquid phase by injecting the gas phase. Parameters which affect the performance of these pumps are divided into two groups. The first group contains design parameters such as diameter of the pipe, tapering angle of the upriser pipe and the submergence ratio which is the ratio of immersed length to the total length of the upriser. The second group includes operating parameters, such as the gas flow rate, bubble diameter, bubble distribution and inlet gas pressure. In this research, the performance of two phase lifting pump is investigated numerically for different submergence ratios and different diameter of the upriser pipe....