Narrow residence time distribution in tubular reactor concept for Reynolds number range of 10–100

2015 ◽  
Vol 95 ◽  
pp. 22-33 ◽  
Author(s):  
Stephan Klutz ◽  
Safa Kutup Kurt ◽  
Martin Lobedann ◽  
Norbert Kockmann
Keyword(s):  
Reynolds Number ◽  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Tubular Reactor ◽  
Number Range ◽  
Reynolds Number Range

scholarly journals Self-similarity of fluid residence time statistics in a turbulent round jet

2017 ◽  
Vol 823 ◽  
pp. 1-25 ◽  
Author(s):  
Dong-hyuk Shin ◽  
R. D. Sandberg ◽  
E. S. Richardson
Keyword(s):  
Reynolds Number ◽  
Probability Density ◽  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Mass Fraction ◽  
The Self ◽  
Similar Profile ◽  
Self Similar ◽  
The Mean

Fluid residence time is a key concept in the understanding and design of chemically reacting flows. In order to investigate how turbulent mixing affects the residence time distribution within a flow, this study examines statistics of fluid residence time from a direct numerical simulation (DNS) of a statistically stationary turbulent round jet with a jet Reynolds number of 7290. The residence time distribution in the flow is characterised by solving transport equations for the residence time of the jet fluid and for the jet fluid mass fraction. The product of the jet fluid residence time and the jet fluid mass fraction, referred to as the mass-weighted stream age, gives a quantity that has stationary statistics in the turbulent jet. Based on the observation that the statistics of the mass fraction and velocity are self-similar downstream of an initial development region, the transport equation for the jet fluid residence time is used to derive a model describing a self-similar profile for the mean of the mass-weighted stream age. The self-similar profile predicted is dependent on, but different from, the self-similar profiles for the mass fraction and the axial velocity. The DNS data confirm that the first four moments and the shape of the one-point probability density function of mass-weighted stream age are indeed self-similar, and that the model derived for the mean mass-weighted stream-age profile provides a useful approximation. Using the self-similar form of the moments and probability density functions presented it is therefore possible to estimate the local residence time distribution in a wide range of practical situations in which fluid is introduced by a high-Reynolds-number jet of fluid.

scholarly journals Effect of oscillation amplitude on the residence time distribution for the mesoscale oscillatory baffled reactor

2017 ◽  
Vol 19 ◽  
pp. 111
Author(s):  
HW Yussof ◽  
SS Bahri ◽  
AN Phan ◽  
AP Harvey
Keyword(s):  
Reynolds Number ◽  
Residence Time ◽  
Oscillation Frequency ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Chemical Engineering ◽  
Continuous Production ◽  
Velocity Ratio ◽  
Small Scale ◽  
Gaussian Form

<p>A recent development in oscillatory baffled reactor technology is down-scaling the reactor, so that it can be used for the applications such as small-scale continuous production of bioethanol. A mesoscale oscillatory baffled reactor (MOBR) with central baffle system was developed and fabricated at mesoscales (typically 5 mm diameter). This present work aims to analyse the mixing conditions inside the MOBR by evaluating the residence time distribution (RTD) against the dynamic parameters of net flow Reynolds number (<em>Re</em><em><sub>n</sub></em>) at 4.2, 8.4 and 12.6 corresponding to flow rates of 1.0, 2.0 and 3.0 ml/min respectively, oscillatory Reynolds number (<em>Re</em><em><sub>o</sub></em>) between 62 to 622, and Strouhal number (<em>Str</em>) between 0.1 to 1.59. The effect of oscillation frequency and amplitude on RTD performance were studied at frequency, amplitude, and velocity ratio ranging from 4 to 8 Hz, 1 to 4 mm and 1 to 118, respectively. Effect of oscillation frequency has resulted in the variance of the RTD increased as the oscillation frequency increased from 5 Hz to 8 Hz and peak at 6 Hz of 0.264. A further increase in the frequency above 5 Hz caused the RTD to slightly broaden and positively skewed. At frequency of 5 Hz, the RTD profiles were close to Gaussian form for all tested amplitude values from 1 mm to 4 mm. At low amplitudes, i.e. xo = 1 mm, the variance exhibited its minimum around 0.842 at <em>Re</em><em><sub>o</sub></em><em> </em>=156. An increase in <em>Re</em><em><sub>o</sub></em><em> </em>above 300 resulted in increased in the variance rapidly to 1.28, and later eliminated the plug flow behaviour and the reactor behaved similar to a single continuous stirred tank reactor.</p><p>Chemical Engineering Research Bulletin 19(2017) 111-117</p>

scholarly journals Spatial and Temporal Validation of a CFD Model Using Residence Time Distribution Test in a Tubular Reactor

Computation ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 94
Author(s):  
José Rivas ◽  
M. Constanza Sadino-Riquelme ◽  
Ignacio Garcés ◽  
Andrea Carvajal ◽  
Andrés Donoso-Bravo
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Fluid Dynamic ◽  
Tubular Reactor ◽  
Temporal Distribution ◽  
Cfd Model ◽  
Ansys Fluent ◽  
Cfd Models ◽  
Temporal Validation

Computational fluid dynamic (CFD) has been increasingly exploited for the design and optimization of (bio)chemical processes. Validation is a crucial part of any modeling application. In CFD, when validation is done, complex and expensive techniques are normally employed. The aim of this study was to test the capability of the CFD model to represent a residence time distribution (RTD) test in a temporal and spatial fashion inside a reactor. The RTD tests were carried out in a tubular reactor operated in continuous mode, with and without the presence of artificial biomass. Two hydraulic retention times of 7.2 and 13 h and superficial velocities 0.65, 0.6, 1.3, and 1.1 m h−1 were evaluated. As a tracer, an aqueous solution of methylene blue was used. The CFD model was implemented in ANSYS Fluent, and to solve the equations system, the SIMPLE scheme and second-order discretization methods were selected. The proposed CFD model that represents the reactor was able to predict the spatial and temporal distribution of the tracer injected in the reactor. The main disagreements between the simulations and the experimental results were observed, especially in the first 50 min of the RTD, caused by the different error sources, associated to the manual execution of the triplicates, as well as some channeling or tracer by-pass that cannot be predicted by the CFD model. The CFD model performed better as the time of the experiment elapsed for all the sampling ports. A validation methodology based on an RTD by sampling at different reactor positions can be employed as a simple way to validate CFD models.

Investigation on a Soft Tubular Model Reactor Based on Bionics of Small Intestine – Residence Time Distribution

2014 ◽  
Vol 10 (4) ◽  
pp. 645-655 ◽  
Author(s):  
Renpan Deng ◽  
Liqing Pang ◽  
Yufen Xu ◽  
Lin Li ◽  
Xuee Wu ◽  
...  
Keyword(s):  
Small Intestine ◽  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Flow Behavior ◽  
Tubular Reactor ◽  
Tubular Reactors ◽  
Fluid Particles ◽  
Mucosal Surface Area ◽  
Structure And Functions

Abstract The human small intestine is responsible for virtually all nutrient uptake and more than 95% of the water absorption in digestion, which is attributed to the vast mucosal surface area and the peristalsis of small intestine. Under the broad conceptual framework of bio-inspired chemical process engineering, by mimicking the structure and functions of small intestine, a flexible tubular reactor with villous protrusions distributed evenly on the inner wall was designed and constructed in this study. In order to understand the flow behavior in the reactor, the residence time distribution (RTD) of fluid particles in the reactor was measured by introducing electrochemical active tracer. Also, a simple mechanism of peristalsis was introduced, and its effects on the RTD in the reactor were investigated. The experimental results showed that the tailing of RTD function curve in the small intestine model reactor was extended significantly compared to a normal tubular reactors. The residence time and mixing of fluid (particles) in the reactor can be regulated efficiently by controlling the peristaltic actions (frequency and location).

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