Hydrodynamics Analysis of a Folding Sieve Tray by Computational Fluid Dynamics Simulation

Hydrodynamics and mass transfer performance of vapor–liquid flow of orthogonal wave tray column

A study of diabatic distillation in a column with a low pressure drop

As a critical gas-liquid contact component, trays play an important role in the performance of distillation column. In this paper, the hydrodynamics of a new type of tray, the total spray tray (TST), were investigated. Taking air-water as the working medium, the pressure drop with different F0 was tested under atmospheric pressure. The results indicate that there is no flooding with the tray and thus the wider operation flexibility can be provided by TST. Furthermore, the pressure drop of TST is much lower than that of other trays. The above properties of TST would benefit the production expansion and energy decreasing in distillation operation greatly.

Experimental study of two phase flow characteristics on the dual-flow tray

The liquid lift-up of directed combined trapezoid spray tray (CTST) was studied. The relationship between Liquid lifting capability of combined CTST and clear liquid height on the plate, F-factor based on tray hole was concluded. In single cap and combined several caps, the change of relative and absolute lift-up was also studied. The effect of F-factor to absolute elevating amount was determined by clear liquid height. On the condition of the higher or the lower clear liquid height, the influence of the F-factor to absolute lift-up was considerable. The relation between the pressure drop inside/outside of the bottom gap and liquid lift-up was studied.

Pressure drop analysis for organic Rankine cycle power generation system using low-grade heat sources

Study on hydrodynamic performance of structured packings for gas-liquid flow: Effects of geometry parameters

Hydrodynamic characteristics of a three-stage dual-flow sieve plate scrubber

Bubbling fluidized beds with horizontal solids crossflow can be broadly grouped according to function: 1) those designed for solids looping, as in indirect pyrolysis or gasification, and chemical or calcium looping; and 2) those employed in high-throughput solids processing, such as drying, iron ore reduction, and pharmaceutical manufacturing. Despite their widespread industrial application and the growing demand for their use in new process designs, there remains a lack of a detailed understanding of the flow characteristics in fluidized beds with horizontal solids throughput. This knowledge gap represents a major challenge for optimizing reactor design and advancing industrial implementation.This thesis aims to develop a mechanistic understanding of how forced horizontal convection of solids in a bubbling fluidized bed influences the solids flow characteristics. The main research objectives are to: (i) assess experimental methods for quantifying the solids circulation rate; (ii) evaluate the efficiencies of different mechanisms to induce horizontal convection of solids; (iii) characterize bed solids transport—specifically, the interrelated effects of solids convection and dispersion—and the resulting fluidization quality; (iv) investigate how the solids crossflow influences overall flow structures; (v) examine the influences of frictional losses on bed solids flow, including the rheological properties of the dense suspension; and (vi) explore how the solids crossflow affects the mixing of a secondary solids phase consisting of large, light particles.Experiments were conducted in a cold-flow model that comprised a closed-loop system in which solids were circulated horizontally via a solids-conveying module. The apparatus was designed and operated according to Glicksman’s simplified scaling laws. In this cold model, fine bronze particles are fluidized with ambient air to fluid-dynamically resemble conditions representative of industrial-scale thermochemical fuel conversion applications. The industrial unit being modeled features a bed channel with a cross-sectional width of 0.92 m and a transport loop length of 10.35 m, in which coarse, sand-like (Geldart B-type) particles are fluidized with flue gas at approximately 800°C.Four measurement methods for quantifying solids circulation were evaluated—namely, integral mass accumulation, differential mass accumulation, thermal tracing, and magnetic solids tracing—with the latter proving to be the most precise and robust. Using this method, five solids-conveying configurations based on different fluid-dynamical mechanisms were tested: (a) free solids splashing, which relies on bubble bursts to eject particles; (b) confined solids splashing, whereby turbulent fluidization creates particle transport that is dominated by eddies and bubble buoyancy; (c) slugging, whereby gas slugs drive particle movement in vertical ducts; (d) solids entrainment, which is achieved by elutriation at high gas velocities; and (e) directed gas injection, which imparts lateral momentum through angled nozzles. Conveying solids under a controlled bubbling fluidization regime was found to be the most efficient configuration for promoting horizontal transport of solids in the system.The horizontal solids flow established in the channel was evaluated under various operational conditions using a combination of experimental and modeling approaches, ranging from reduced-order descriptions to Eulerian–Eulerian computational fluid dynamics (CFD) simulations. A positive linear relationship was observed between the solids dispersion coefficient and the mean solids velocity, both evaluated in the streamwise direction. This was further explained by the CFD simulations, which indicated that at low crossflow rates, the solids flow organizes into coherent, counter-rotating vortices along the bubble paths. In contrast, at high crossflow rates, these structures are disrupted, resulting in less streamlined (stronger mixing) and more elongated (longer characteristic lengths) flow patterns. In addition, microscale dispersion was found to be dominated by bubble- and eddy-induced mixing, rather than by random particle motion or collisions. Rheological analysis revealed that the bed exhibits shear-thinning behavior and that single-phase models for non-circular open-flow channels underestimate the influence of geometry on gas-solids flows.Analysis of the transport behavior of large, light particles added to the bed as a lean phase showed that, similar to bulk solids, a positive correlation exists between dispersion and convection, with sensitivity strongly dependent on the degree of fluidization. The dispersion of the lean particles was greater than that of the bulk solids; it remained at a similar level for both low and high fluidization velocities. However, compared to the bulk solids, the lean particles were transported at lower convection velocities under high fluidization levels. In contrast, at low fluidization levels, the particles formed a layer above the dense bed and were conveyed in a plug-like manner, exhibiting much higher horizontal velocities than the bulk solids.

Numerical simulation of binary component separation with perforated-on sheets of the structured packing

The microtube length significantly influences the convective boiling process and associated heat transfer characteristics. Other than high heat transfer, low pressure drop is also desired to improve the energy efficiency of the pumping system. This work numerically investigates the microtube length effect on heat transfer and pressure drops of convective boiling with the volume of fluid (VOF) method. The simulation results of vapor formation, heat transfer coefficient, and pressure drop are shown with different microtube lengths L = 2–20 mm. The onset of boiling is around 2 mm away from the mass flux inlet. The subcooled boiling regime can be observed between 2 and 10 mm. Three distinct regimes, liquid single-phase flow, bubbly flow, and plug flow, are shown in the longer microtubes (L = 15 mm and 20 mm). It is found that shorter microtubes can lead to less bubble formation with higher heat transfer and lower pressure drop. The average heat transfer coefficient can achieve 2432 W/(m2K) with a lower quasi-steady total pressure drop Δp|total of 32.8 Pa inside a 2-mm-long microtube. This work offers a detailed study of the impact of microtube length on convective boiling, along with pertinent physical insights. It may serve as an indicator for future microscale heat transfer application designs.

Modeling fixed triangular valve tray hydraulics using computational fluid dynamics

CFD simulations of turbulent flow in baffle-filled membrane tubes

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTClear liquid height and froth density on sieve traysCharles J. ColwellCite this: Ind. Eng. Chem. Process Des. Dev. 1981, 20, 2, 298–307Publication Date (Print):April 1, 1981Publication History Published online1 May 2002Published inissue 1 April 1981https://pubs.acs.org/doi/10.1021/i200013a019https://doi.org/10.1021/i200013a019research-articleACS PublicationsRequest reuse permissionsArticle Views837Altmetric-Citations60LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts

Rationale: We previously found oropharyngeal enlargement and subglottal narrowing in asthma and chronic obstructive pulmonary disease (COPD) patients compared to healthy individuals. This study aimed to investigate the impact of oropharyngeal remodeling on the upper airway airflow dynamics in association with lung structure-function impairment in obstructive lung disease (OLD). Methods: Upper airway computed tomography (CT) scans, inspiratory (total lung capacity) and expiratory (functional residual capacity) lung CTs, and clinical data were collected from 185 participants (26 healthy, 56.6±5.1y; 73 COPD, 71.1±7.5y, and 86 asthma, 64.8±12.5y) enrolled in Jeonbuk National University Hospital, Jeonju, Korea. We conducted quantitative inspiratory-expiratory CT analysis and one-dimensional (1D) computational fluid dynamics (CFD) simulations of airflow in the lower airways, for all participants. Then, we selected ten representative subjects in each group based on key features of upper airways (healthy: 56±6.2y; COPD: 69.7±7.4y; asthma: 63.2±6.3y) and conducted three-dimensional (3D) CFD simulations of breathing (tidal volume: 6 ml/kg). Results: Patients with OLD showed 11 times greater CFD-derived lower airway resistance and 3.8% smaller transpulmonary pressure than healthy controls. 3D CFD simulations showed less pressure drop from the mouth to the level of the sixth cervical vertebra (C6) during inhalation in OLD (COPD: 37.3±41.9Pa; asthma: 32.01±18.4 Pa) than in healthy subjects (70.7±48.5) Pa. Upper (oropharyngeal) airway resistance was also smaller in OLD (COPD: 155.0±188.0 kPa·s/m³; asthma: 116.2±61.5 kPa·s/m³) than in healthy subjects (229.4±142.2 kPa·s/m³). This is attributable to oropharyngeal enlargement measured by greater oral space air fraction and larger supraglottal airway diameter at the level of the fourth cervical vertebra (C4). Less upper airway pressure drop to the level of C6 correlated with upper airway enlargement measured by normalized upper airway air volume (r=-0.60, p<0.001) and diameter at C4 (r=-0.56, p=0.001) as well as lung structure-function impairment such as functional small airways disease percent (fSAD%), less volumetric deformation (J), and less relative displacement (s[asterisk]) (r=-0.40, 0.47, 0.54; p=0.030, 0.009, 0.002) and worse spirometry outcomes such as post-BD FEV1% (r=0.54, p=0.002) and FEV1/FVC (r=0.54, p=0.002). Conclusion: CT-based CFD simulations showed patients with obstructive lung disease experienced elevated airway resistance in the lower airways but reduced pressure drop and airway resistance due to oropharyngeal enlargement during inhalation. Reduced aerodynamic effort may help compensate excessive respiratory effort required in the lower airways. Findings suggest that upper airway imaging and airflow analysis allows more complete interpretation of the entire respiratory function altered with airflow obstruction.