Thermodynamics,
Salman Movahedirad; Ali Akbar Sarbanha; Fahimeh Sobhanian
Volume 13, Issue 3 , July 2016, , Pages 32-42
Abstract
A Laser Induced Fluorescence technique (LIF) has been used to study the mixing behavior of two emerging streams in a T-Type mixing chamber. A mixing index on the basis of digital image light intensities is calculated. It has been shown that averaging over more than 800 images leads to a stable mixing ...
Read More
A Laser Induced Fluorescence technique (LIF) has been used to study the mixing behavior of two emerging streams in a T-Type mixing chamber. A mixing index on the basis of digital image light intensities is calculated. It has been shown that averaging over more than 800 images leads to a stable mixing index calculation. Moreover, the effect of equal and un-equal flow rates on the mixing behavior of the streams has been studied. The results show that the histograms of the light intensity changes from double peak (unmixed) to a single peak (mixed) at high elevations of the chamber. Mixing index has a linear descending behavior moving toward the cell front wall and it was shown that the mixing index can be reduced up to 50% moving from cell center to near wall region. Moreover, there is a transition zone in both equal and un-equal fluid flow rates in mixing index. It was shown that the third component velocity play an important role in mixing behavior in T-Type mixing chamber.
Process Control and Engineering, Process Safety, HSE
A. Dehghan Lotfabad; S. Movahedirad; M.T. Sadeghi
Volume 13, Issue 1 , January 2016, , Pages 60-72
Abstract
Digital Image Analysis (DIA) has been employed to characterize the time evolution of a bubble injected from a single orifice into a pseudo 2-dimansional gas-solid fluidized bed. The injected bubble diameter increased with the square root of time before detachment. During bubble free flight in the bed, ...
Read More
Digital Image Analysis (DIA) has been employed to characterize the time evolution of a bubble injected from a single orifice into a pseudo 2-dimansional gas-solid fluidized bed. The injected bubble diameter increased with the square root of time before detachment. During bubble free flight in the bed, its diameter remains approximately constant. The center of mass of the bubble increases with the second power of the time. The results show that the classical models for bubble injection can predict the time evolution of bubble diameter, and its center of mass. Bubble tends to elongate during injection and after detachment its height to width aspect ratio decreases. Image analyzing results used also for the study of gas leakage from the bubble to emulsion phase, and it has been shown that the dense phase expands up to 1.04 times of the minimum fluidization condition for large bubbles. The expansion ratio of the dense phase increases linearly with bubble diameter.