Search results for "Plug flow"

Supercritical CO2 extraction of essential oil from orange peel. Effect of operation conditions on the extract composition

1999

Abstract The supercritical fluid extraction (SFE) of orange essential oil was studied using dehydrated orange peel (0.0538 kg H2O/kg dm) from naveline cultivars as raw material and CO2 as solvent. The effect of operation conditions was analyzed in a series of experiments at temperatures between 293 and 323 K and pressures between 8 and 28 MPa. The collected extracts were analyzed and the relative composition of the essential oil was determined. Limonene was the principal component extracted, the optimum conditions for limonene extraction were 12.5 MPa and 308 K, in these conditions limonene represents more than 99.5% of the essential oil. Within the operating range conditions, the optimum f…

Experimental and fluid dynamic study of continuous supercritical water gasification of glucose

2016

Abstract The supercritical water gasification (SCWG) of glucose as a model compound for H 2 production is studied in term of process development at 25 MPa and 650 °C. Gasification has been investigated using a laboratory scale continuous plant comprising a continuous down flow reactor with a volume of 200 cm 3 , a heat recovery section and pre-heat of the biomass to simulate more closely an industrial design. Feed streams (pure water and glucose solution) are introduced at the top of the vessel and products are extracted from the bottom. The reactor is equipped with various inlet points that allow to modify the inlet position of reacting streams in order to study the effect of stream mixing…

Turbulence structure and budgets in curved pipes

2013

Abstract Turbulent flow in curved pipes was investigated by Direct Numerical Simulation. Three curvatures δ (pipe radius a /curvature radius c ) were examined: δ  = 0 (straight pipe), simulated for validation and comparison purposes; δ  = 0.1; and δ  = 0.3. The friction velocity Reynolds number (based on the pipe radius a ) was 500 in all cases, yielding bulk Reynolds numbers of ∼17,000, ∼15,000 and ∼12,000 for δ  = 0, 0.1 and 0.3, respectively. The computational domain was ten pipe radii in length and was resolved by up to 20 × 10 6 hexahedral finite volumes. The time step was chosen equal to a wall time unit; 1 Large Eddy TurnOver Time (LETOT) was thus resolved by 500 time steps and simul…

Modelling wet-air oxidation of phenol in a trickle-bed reactor using active carbon as a catalyst

2016

The Application of CFD Methods for Modeling of a Three-Phase Fixed-Bed Reactor

2018

The mathematical model of the three-phase fixed-bed reactor (TBR) consisting of the continuity equation, the momentum balances of each phase and mass balances of reaction mixture components were presented and discussed. These balances are the result of averaging by means of Euler’s procedure and form the basis of the Computational Fluid Dynamics (CFD). Although the CFD model is based on fundamental principles some empirical relations (closure lows) must be implemented into the momentum balance in order to ensure a proper description of the dynamics of very complex three-phase system. Therefore, the sensitivity of a multiphase CFD model with respect to relations defining drag forces between …

Kinetic study of ionic liquid synthesis in a microchannel reactor

2010

Abstract A microchannel reaction system, mainly consisting of a micromixer and a tubular reactor, was used to investigate the kinetics of butylation of 1-methyl-imidazole [MIM] for the synthesis of the ionic liquid 1-butyl-3-methylimidazolium bromide ([BMIM]Br). The low variance (σθ2 = 0.019) of the residence time distribution, measured by a step stimuli–response tracer method, implies that this reaction system could be regarded as a plug flow reactor. As a fast and reliable method, the titration of bromide was established to determine the yield of [BMIM]Br. The reaction kinetics was studied by varying the molar ratio of 1-bromobutane [BrBu] to [MIM] (1.04–1.49) and temperature (75–90 °C). …

Two-Dimensional Modeling of a Flat-Plate Photocatalytic Reactor for Oxidation of Indoor Air Pollutants

2007

In this paper we present a two-dimensional (2-D) analysis of a narrow-slit, flat-plate, single-pass, flow-through photocatalytic reactor for air purification. The continuity equation for convection and diffusion in two dimensions, under un-steady-state conditions, was coupled with radiation field modeling and photocatalytic reaction kinetics to model the transient and steady-state behavior of the reactor. The model was applied to the photocatalytic oxidation of trichloroethylene (TCE) in humidified air streams under different experimental conditions. The kinetic parameters determined by a three-dimensional (3-D) computational fluid dynamics model of the reactor were used in the 2-D model si…

MODELING OF A TiO2-COATED QUARTZ -WOOL PACKED-BED PHOTOCATALYTIC REACTOR

2010

A fixed-bed, photocatalytic laboratory reactor aimed to degrade pollutants from water streams was designed and built. Quartz wool coated with a thin film of TiO2 was employed as the reactor filling. The photocatalyst was placed in the reactor forming a loose packing to guarantee the intimate contact among reactants, photons, and the photocatalytic surface. This reactor was employed to study the photocatalytic decomposition of a model pollutant (formic acid). A reactor–radiation–reaction model was developed, which was comprised of the reactor mass balance, radiation model, and kinetic model for the degradation of formic acid. The local superficial rate of photon absorption, which was necessa…

Hydrodynamic characterization of a new small-scale reactor mixed by a magnetic bar

2015

International audience; The purpose of this study was to evaluate the mixing characteristics of a new milliliter-scale (mL-scale) reactor developed for studying enzymatic activity or physiological cell response. The mL-scale reactor was designed to enable the integration of several sensors to carry out dynamic measurements in a controlled environment. Rapid homogeneity of the entire system is essential to ensure reproducible and reliable results, consequently the reactor was stirred to optimize both mass and heat transfers. A comparative study using three different techniques was undertaken to study mixing performances in the system. Firstly, mixing time (4,) was estimated in the reactor us…

Modelling wet-air oxidation of phenol in a trickle-bed reactor using active carbon as a catalyst

2014

BACKGROUND Catalytic wet air oxidation (CWAO) of phenol in a trickle-bed reactor has been investigated (operating parameters: P=1.85 MPa, T=393, 413, 433 K, L=0.17–1.77 kg m−2 s−1 and G=0.2–0.62 kg m−2 s−1). Activated carbon was used as a catalyst. The experimental results have been simulated by Eulerian multifluid model (CFD) and for comparison by the plug flow model. RESULTS The experiments proved that active carbon can be applied as a catalyst in the phenol oxidation processes revealing a catalytic activity comparable with that of commonly used metal oxides. The highest conversion of phenol obtained in long-lasting experimental runs carried out at stable catalytic activity (PO2 = 0.31 MP…