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Countercurrent exchange

About: Countercurrent exchange is a research topic. Over the lifetime, 2255 publications have been published within this topic receiving 28687 citations. The topic is also known as: Countercurrent exchange.


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Journal ArticleDOI
TL;DR: A mathematical model for the fractionation of liquids with supercritical CO 2 in a countercurrent packed column is presented in this article, which is based on the differential mass and energy balances over the height of the extractor, which are solved numerically.
Abstract: A mathematical model for the fractionation of liquids with supercritical CO 2 in a countercurrent packed column is presented. This model is based on the differential mass and energy balances over the height of the extractor, which are solved numerically. The phase behavior of the multicomponent systems of interest for this process is represented with the Peng–Robinson Equation of State. Volumetric and thermal properties of the fluids are also calculated with the PR-EOS. Transport properties are estimated applying suitable correlations. This model includes the coupled mass and heat transfer in the interface between the two fluid phases. Since the model includes the energy balance, it is possible to study the operation with a gradient of temperature over the height of the extractor. The model has been validated comparing the predictions with experimental data for the fractionation of edible oil mixtures and the separation of fish oil ethyl esters taken from the literature. The correlation between experimental and calculated results is reasonably good, and the model predicts correctly the trends of variation with the different operating and design parameters.

32 citations

Journal ArticleDOI
TL;DR: In this paper, the authors describe the application of countercurrent shear flow control to the nonreacting flow in a novel step combustor, which employs a suction based approach, which induces counterflow through a gap at the sudden expansion plane.
Abstract: The present work describes the application of countercurrent shear flow control to the nonreacting flow in a novel step combustor. The countercurrent shear control employs a suction based approach, which induces counterflow through a gap at the sudden expansion plane. Peak turbulent fluctuation levels, cross-stream averaged turbulent kinetic energy, and cross-stream momentum diffusion increased with applied suction. The control downstream of the step operates via two mechanisms: enhanced global recirculation and near field control of the separated shear layer. The use of counterflow also enhances three dimensionality, a feature that is expected to be beneficial under burning conditions.

31 citations

Journal ArticleDOI
TL;DR: In this paper, a model of turbulent two-fluid flow is applied to the simulation of hydrodynamics in discs and doughnuts pulsed columns, and the authors demonstrate a possibility for prediction of the mean column hold-up using the Eulerian approach.

31 citations

Patent
10 Dec 2009
TL;DR: In this paper, a countercurrent process for converting solid biomass material is described, where the solid biomass is subjected to a first conversion at a first temperature T 1 and a second conversion at the second temperature T 2 such that T 2 > T 1.
Abstract: A countercurrent process is disclosed for converting solid biomass material. The solid biomass material travels through a reactor system in countercurrent with hot heat carrier materials, such as particulate heat earner material and hot gases. The solid biomass material is subjected to a first conversion at a first temperature T 1. and a second conversion at a second temperature, T 2, such that T 2 > T 1. Bio-oil produced to at T J is not exposed to the higher temperature T 2. As a result, secondary reactions of the bio-oii components are minimized.

31 citations

Journal ArticleDOI
TL;DR: In this article, a three-dimensional Computational Fluid Dynamics (CFD) model was developed that applies to the two-phase countercurrent flow on an inclined and flat plate, based on the volume-of-fluid (VOF) method, considering the gravity, surface tension and the drag force between the two phases.
Abstract: The design of packed columns requires the detailed description of the hydrodynamics on the surface of the packings. To analyze the local flow behavior of the liquid phase, a three-dimensional Computational Fluid Dynamics (CFD) model was developed that applies to the two-phase countercurrent flow on an inclined and flat plate. This model, based on the volume-of-fluid (VOF) method, considers the gravity, the surface tension and the drag force between the two phases. The development of such a model allows investigation of the influences of the liquid and gas flow rates on the flow behavior such as the film flow and the rivulet flow. A validation of the model was performed using data from the literature and from experiments conducted in this work. Simulation and experimental results demonstrate that the specific wetted area on the plate decreases with decreasing liquid load. Moreover, CFD simulations reveal that the presence of the countercurrent gas phase tends to increase the fluctuation and the thickness of the film flow, which is in accordance with experimental data. It also affects the flow behavior of the rivulet flow and changes the velocity profiles for both film and rivulet flow behavior. On the other hand, the simulation results indicate that CFD is a potent tool for analyzing and investigating the flow phenomena in chemical engineering.

31 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202358
2022115
202127
202041
201947
201849