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.

Dynamic Large-Eddy Simulation of Droplet Effects on a Reacting Plume in Countercurrent Configuration

Abstract: The effects of evaporating droplets on a reacting plume have been investigated using large-eddy simulation (LES) with dynamic subgrid flow models. A countercurrent configuration, in which droplets are discharged downward toward a rising buoyant reacting plume, is used to mimic an idealized small-scale, water-based fire suppression system. Parametric studies have been conducted by varying the initial Stokes number (St 0) or nondimensional droplet size, volumetric flow rate of the spray nozzle or equivalent mass loading ratio (MLR 0), and initial droplet speed ( ), independently. The interactions between the two phases are studied in both instantaneous and statistical means. The thermal and dynamic effects of droplets on the reacting plume are scrutinized using the transport equations for the filtered (reduced) internal energy and filtered kinetic energy of the gas phase. New insights on the droplet effects have been gained by rearranging the droplet source terms in the transport equations into physically m...

Analytical Study of Critical Heat Flux under Countercurrent Flow Limitation in Vertical Channels

Abstract: A quantitative analysis of critical heat flux (CHF) under countercurrent flow limitation (CCFL) or flooding was successfully carried out using the existing experimental results for the vertical circular, rectangular and annular channels, applying the criteria, which was proposed by the author, that the CCFL condition could be determined by maximizing the water mass flux falling down in the vertical channels with respect to the water film thickness and the model of dryout of water film flow at the CHF point. It was clarified that the analytical results give good predictions of the existing experimental results of vertical channels, identifying the factors determining the CHF under the CCFL conditions.

Processing of high normal paraffin concentration naphtha feedstocks

Abstract: Normal paraffins present in high concentrations in light naphtha streams are separated from non-normal paraffins in a four or more bed adsorption system employing, on a cyclic basis, the processing steps of (1) cocurrent purge/adsorption, (2) cocurrent feed/adsorption, (3) countercurrent purge and (4) countercurrent displacement. A processing sequence is employed wherein the cocurrent purge/adsorption and countercurrent purge steps are carried out on a discontinuous basis, while cocurrent feed/adsorption and countercurrent displacement steps are carried out in overlapping sequence. Control means are provided to assure that the high normal paraffin-containing hydrocarbon feed gas and stripping gas are passed to the appropriate beds for said cocurrent purge/adsorption and countercurrent purge steps on a non-continuous basis, said feed gas being continuously fed to a mix drum for mixture with countercurrent purge effluent before removal for use in said cocurrent purge/adsorption step and in said cocurrent feed/adsorption step of the overall four-step process.