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Pongjet Promvonge - One of the best experts on this subject based on the ideXlab platform.
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thermal characterization in a circular tube fitted with inclined horseshoe Baffles
Applied Thermal Engineering, 2015Co-Authors: Pongjet Promvonge, Sombat Tamna, Monsak Pimsarn, Chinaruk ThianpongAbstract:Abstract In the present study, the influence of inclined horseshoes Baffles placed repeatedly in a tubular heat exchanger on heat transfer rate, friction factor and thermal enhancement factor are experimentally determined. The horseshoe Baffle elements with an inclination angle of 20° were inserted periodically into the test tube at three different Baffle-pitch ratios ( P R = 0.5, 1.0 and 2) and -width or blockage ratios ( B R = 0.1, 0.15 and 0.2). The experiment was conducted in the test tube having a uniform heat-fluxed wall by varying turbulent airflow to obtain Reynolds number in a range of 5300–24,000. The experimental results revealed that the tube fitted with inclined horseshoes Baffles provides considerable improvement of the heat transfer rate over the plain tube around 92–208% while the friction factor is increased at about 1.76–6.37 times. To access the real benefits for the inclined horseshoes Baffles inserted in plain tube, thermal performance factor is examined and found to be in the range of 1.34–1.92 at which the maximum obtained at P R = 0.5 and B R = 0.1 is considerably higher than that for published inserted devices. Correlations for Nusselt number and friction factor for the oblique horseshoe-Baffled tube are also proposed.
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experimental and numerical study on heat transfer enhancement in a channel with z shaped Baffles
International Communications in Heat and Mass Transfer, 2012Co-Authors: Parkpoom Sriromreun, Chinaruk Thianpong, Pongjet PromvongeAbstract:Abstract The influence of Baffle turbulators on heat transfer augmentation in a rectangular channel has been investigated experimentally and numerically. In the experiment, the Baffles are placed in a zigzag shape (Z-shaped Baffle) aligned in series on the isothermal-fluxed top wall, similar to the absorber plate of a solar air heater channel. The aim at using the Z-Baffles is to create co-rotating vortex flows having a significant influence on the flow turbulence intensity leading to higher heat transfer enhancement in the tested channel. Effects of the Z-Baffle height and pitch spacing length are examined to find the optimum thermal performance for the Reynolds number from 4400 to 20,400. The Z-Baffles inclined to 45° relative to the main flow direction are characterized at three Baffle- to channel-height ratios (e/H = 0.1, 0.2 and 0.3) and Baffle pitch ratios (P/H = 1.5, 2 and 3). The experimental results show a significant effect of the presence of the Z-Baffle on the heat transfer rate and friction loss over the smooth channel with no Baffle. The Nusselt number, friction factor and thermal performance enhancement factor for the in-phase 45° Z-Baffles are found to be considerably higher than those for the out-phase 45° Z-Baffle at a similar operating condition. The in-phase 45° Z-Baffle with larger e/H provides higher heat transfer and friction loss than the one with smaller e/H while the shorter pitch length yields the higher Nu, f and TEF than the larger one. The numerical work is also conducted to investigate the flow friction and heat transfer behaviors in the channel mounted with the 45° Z-Baffles, and the numerical results are found in good agreement with experimental data.
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3d simulation of laminar flow and heat transfer in v Baffled square channel
International Communications in Heat and Mass Transfer, 2012Co-Authors: Pongjet Promvonge, Sutapat Kwankaomeng, Chinaruk ThianpongAbstract:Abstract The article presents a numerical investigation on laminar flow and heat transfer characteristics in a three-dimensional isothermal wall square-channel fitted with inline 45° V-shaped Baffles on two opposite walls. The computations based on the finite volume method with the SIMPLE algorithm have been conducted for the airflow in terms of Reynolds numbers ranging from 200 to 2000. The inline V-Baffles with its V-tip pointing downstream and the attack angle (or half V-apex angle) of 45° relative to the flow direction are mounted repeatedly on the lower and upper walls. The Baffled channel flow shows a fully developed periodic flow and heat transfer profile for BR = 0.2 at x/D≈ 8 downstream of the inlet. Influences of different Baffle height ratios (BR) and pitch ratios, (PR) on thermal behaviors for a fully developed periodic condition are investigated. It is apparent that the longitudinal counter-rotating vortex flows created by the V-Baffle can induce impingement/attachment flows over the walls resulting in greater increase in heat transfer over the test channel. Apart from speeding up the fully developed periodic flow pattern, the rise of the BR leads to the increase in Nu/Nu0 and f/f0 values while that of the PR provides an opposite trend. The V-Baffle performs better than the angled Baffle at a similar condition. The V-Baffle with BR = 0.2 and PR = 1.5 yields the maximum thermal performance of about 3.8 whereas the Nu/Nu0 is some 14 times above the smooth channel at higher Re.
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numerical prediction on laminar heat transfer in square duct with 30 angled Baffle on one wall
International Communications in Heat and Mass Transfer, 2010Co-Authors: Sutapat Kwankaomeng, Pongjet PromvongeAbstract:Abstract A numerical investigation on periodic laminar flow and heat transfer behaviors in a three-dimensional isothermal wall square duct fitted with 30° angled Baffles on lower duct wall only is presented. The computations based on a finite volume method with the SIMPLE algorithm have been conducted for the fluid flow in terms of Reynolds numbers ranging from 100 to 2000. The angled Baffles with attack angle of 30° are mounted periodically on the lower duct wall to generate a longitudinal vortex flow through the tested duct. Effects of different Baffle height and three pitch length ratios on heat transfer and flow characteristics in the duct are investigated. The study shows that the longitudinal vortex flow created by the Baffle helps to induce impinging flows over the Baffle trailing end sidewall and the inter-Baffle cavity wall resulting in drastic increase in heat transfer rate over the test duct. The computational results reveal that the Nusselt number ratio and the maximum thermal enhancement factor values for using the angled Baffle are, respectively, found to be about 7.9 and 3.1 at Re = 2000, BR = 0.3 and PR=1.5.
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periodic laminar flow and heat transfer in a channel with 45 staggered v Baffles
International Communications in Heat and Mass Transfer, 2010Co-Authors: Pongjet Promvonge, Sutapat KwankaomengAbstract:Abstract A numerical investigation has been carried out to examine periodic laminar flow and heat transfer characteristics in a three-dimensional isothermal wall channel of aspect ratio, AR = 2 with 45° staggered V-Baffles. The computations are based on the finite volume method, and the SIMPLE algorithm has been implemented. The fluid flow and heat transfer characteristics are presented for Reynolds numbers based on the hydraulic diameter of the channel ranging from 100 to 1200. To generate two pair of main streamwise vortex flows through the tested section, V-Baffles with an attack angle of 45° are mounted in tandem and staggered arrangement on the lower and upper walls of the channel. Effects of different Baffle heights on heat transfer and pressure drop in the channel are studied and the results of the V-Baffle pointing upstream are also compared with those of the V-Baffle pointing downstream. It is apparent that in each of the main vortex flows, a pair of streamwise twisted vortex (P-vortex) flows can induce impinging flows on a sidewall and a wall of the interBaffle cavity leading to drastic increase in heat transfer rate over the channel. In addition, the rise in the V-Baffle height results in the increase in the Nusselt number and friction factor values. The computational results reveal that the optimum thermal enhancement factor is around 2.6 at Baffle height of 0.15 times of the channel height for the V-Baffle pointing upstream while is about 2.75 at Baffle height of 0.2 times for the V-Baffle pointing downstream.
Sutapat Kwankaomeng - One of the best experts on this subject based on the ideXlab platform.
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3d simulation of laminar flow and heat transfer in v Baffled square channel
International Communications in Heat and Mass Transfer, 2012Co-Authors: Pongjet Promvonge, Sutapat Kwankaomeng, Chinaruk ThianpongAbstract:Abstract The article presents a numerical investigation on laminar flow and heat transfer characteristics in a three-dimensional isothermal wall square-channel fitted with inline 45° V-shaped Baffles on two opposite walls. The computations based on the finite volume method with the SIMPLE algorithm have been conducted for the airflow in terms of Reynolds numbers ranging from 200 to 2000. The inline V-Baffles with its V-tip pointing downstream and the attack angle (or half V-apex angle) of 45° relative to the flow direction are mounted repeatedly on the lower and upper walls. The Baffled channel flow shows a fully developed periodic flow and heat transfer profile for BR = 0.2 at x/D≈ 8 downstream of the inlet. Influences of different Baffle height ratios (BR) and pitch ratios, (PR) on thermal behaviors for a fully developed periodic condition are investigated. It is apparent that the longitudinal counter-rotating vortex flows created by the V-Baffle can induce impingement/attachment flows over the walls resulting in greater increase in heat transfer over the test channel. Apart from speeding up the fully developed periodic flow pattern, the rise of the BR leads to the increase in Nu/Nu0 and f/f0 values while that of the PR provides an opposite trend. The V-Baffle performs better than the angled Baffle at a similar condition. The V-Baffle with BR = 0.2 and PR = 1.5 yields the maximum thermal performance of about 3.8 whereas the Nu/Nu0 is some 14 times above the smooth channel at higher Re.
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numerical prediction on laminar heat transfer in square duct with 30 angled Baffle on one wall
International Communications in Heat and Mass Transfer, 2010Co-Authors: Sutapat Kwankaomeng, Pongjet PromvongeAbstract:Abstract A numerical investigation on periodic laminar flow and heat transfer behaviors in a three-dimensional isothermal wall square duct fitted with 30° angled Baffles on lower duct wall only is presented. The computations based on a finite volume method with the SIMPLE algorithm have been conducted for the fluid flow in terms of Reynolds numbers ranging from 100 to 2000. The angled Baffles with attack angle of 30° are mounted periodically on the lower duct wall to generate a longitudinal vortex flow through the tested duct. Effects of different Baffle height and three pitch length ratios on heat transfer and flow characteristics in the duct are investigated. The study shows that the longitudinal vortex flow created by the Baffle helps to induce impinging flows over the Baffle trailing end sidewall and the inter-Baffle cavity wall resulting in drastic increase in heat transfer rate over the test duct. The computational results reveal that the Nusselt number ratio and the maximum thermal enhancement factor values for using the angled Baffle are, respectively, found to be about 7.9 and 3.1 at Re = 2000, BR = 0.3 and PR=1.5.
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periodic laminar flow and heat transfer in a channel with 45 staggered v Baffles
International Communications in Heat and Mass Transfer, 2010Co-Authors: Pongjet Promvonge, Sutapat KwankaomengAbstract:Abstract A numerical investigation has been carried out to examine periodic laminar flow and heat transfer characteristics in a three-dimensional isothermal wall channel of aspect ratio, AR = 2 with 45° staggered V-Baffles. The computations are based on the finite volume method, and the SIMPLE algorithm has been implemented. The fluid flow and heat transfer characteristics are presented for Reynolds numbers based on the hydraulic diameter of the channel ranging from 100 to 1200. To generate two pair of main streamwise vortex flows through the tested section, V-Baffles with an attack angle of 45° are mounted in tandem and staggered arrangement on the lower and upper walls of the channel. Effects of different Baffle heights on heat transfer and pressure drop in the channel are studied and the results of the V-Baffle pointing upstream are also compared with those of the V-Baffle pointing downstream. It is apparent that in each of the main vortex flows, a pair of streamwise twisted vortex (P-vortex) flows can induce impinging flows on a sidewall and a wall of the interBaffle cavity leading to drastic increase in heat transfer rate over the channel. In addition, the rise in the V-Baffle height results in the increase in the Nusselt number and friction factor values. The computational results reveal that the optimum thermal enhancement factor is around 2.6 at Baffle height of 0.15 times of the channel height for the V-Baffle pointing upstream while is about 2.75 at Baffle height of 0.2 times for the V-Baffle pointing downstream.
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laminar periodic flow and heat transfer in square channel with 45 inline Baffles on two opposite walls
International Journal of Thermal Sciences, 2010Co-Authors: Pongjet Promvonge, Somchai Sripattanapipat, Sutapat KwankaomengAbstract:Abstract A numerical investigation has been carried out to examine laminar flow and heat transfer characteristics in a three-dimensional isothermal wall square channel with 45°-angled Baffles. The computations are based on the finite volume method, and the SIMPLE algorithm has been implemented. The fluid flow and heat transfer characteristics are presented for Reynolds numbers based on the hydraulic diameter of the channel ranging from 100 to 1000. To generate a pair of mainstreamwise vortex flows through the tested section, Baffles with an attack angle of 45° are mounted in tandem and inline arrangement on the lower and upper walls of the channel. Effects of different Baffle heights on heat transfer and pressure loss in the channel are studied and the results of the 45° inline Baffle are also compared with those of the 90° transverse Baffle and the 45° staggered Baffle. It is apparent that in each of the main vortex flows, a pair of streamwise twisted vortex (P-vortex) flows created by the 45° Baffle exist and help to induce impinging flows on a sidewall and wall of the Baffle cavity leading to drastic increase in heat transfer rate over the channel. In addition, the rise in the Baffle height results in the increase in the Nusselt number and friction factor values. The computational results reveal that numerical results of both the 45° inline and staggered Baffles are nearly the same. The optimum thermal enhancement factor is at the 45° Baffle height of 0.2 times of the channel height for both arrays. The maximum thermal enhancement factor of the 45° Baffle in the Re range studied is found to be about 2.6 or twice higher than that of the 90° transverse Baffle.
Chinaruk Thianpong - One of the best experts on this subject based on the ideXlab platform.
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thermal characterization in a circular tube fitted with inclined horseshoe Baffles
Applied Thermal Engineering, 2015Co-Authors: Pongjet Promvonge, Sombat Tamna, Monsak Pimsarn, Chinaruk ThianpongAbstract:Abstract In the present study, the influence of inclined horseshoes Baffles placed repeatedly in a tubular heat exchanger on heat transfer rate, friction factor and thermal enhancement factor are experimentally determined. The horseshoe Baffle elements with an inclination angle of 20° were inserted periodically into the test tube at three different Baffle-pitch ratios ( P R = 0.5, 1.0 and 2) and -width or blockage ratios ( B R = 0.1, 0.15 and 0.2). The experiment was conducted in the test tube having a uniform heat-fluxed wall by varying turbulent airflow to obtain Reynolds number in a range of 5300–24,000. The experimental results revealed that the tube fitted with inclined horseshoes Baffles provides considerable improvement of the heat transfer rate over the plain tube around 92–208% while the friction factor is increased at about 1.76–6.37 times. To access the real benefits for the inclined horseshoes Baffles inserted in plain tube, thermal performance factor is examined and found to be in the range of 1.34–1.92 at which the maximum obtained at P R = 0.5 and B R = 0.1 is considerably higher than that for published inserted devices. Correlations for Nusselt number and friction factor for the oblique horseshoe-Baffled tube are also proposed.
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experimental and numerical study on heat transfer enhancement in a channel with z shaped Baffles
International Communications in Heat and Mass Transfer, 2012Co-Authors: Parkpoom Sriromreun, Chinaruk Thianpong, Pongjet PromvongeAbstract:Abstract The influence of Baffle turbulators on heat transfer augmentation in a rectangular channel has been investigated experimentally and numerically. In the experiment, the Baffles are placed in a zigzag shape (Z-shaped Baffle) aligned in series on the isothermal-fluxed top wall, similar to the absorber plate of a solar air heater channel. The aim at using the Z-Baffles is to create co-rotating vortex flows having a significant influence on the flow turbulence intensity leading to higher heat transfer enhancement in the tested channel. Effects of the Z-Baffle height and pitch spacing length are examined to find the optimum thermal performance for the Reynolds number from 4400 to 20,400. The Z-Baffles inclined to 45° relative to the main flow direction are characterized at three Baffle- to channel-height ratios (e/H = 0.1, 0.2 and 0.3) and Baffle pitch ratios (P/H = 1.5, 2 and 3). The experimental results show a significant effect of the presence of the Z-Baffle on the heat transfer rate and friction loss over the smooth channel with no Baffle. The Nusselt number, friction factor and thermal performance enhancement factor for the in-phase 45° Z-Baffles are found to be considerably higher than those for the out-phase 45° Z-Baffle at a similar operating condition. The in-phase 45° Z-Baffle with larger e/H provides higher heat transfer and friction loss than the one with smaller e/H while the shorter pitch length yields the higher Nu, f and TEF than the larger one. The numerical work is also conducted to investigate the flow friction and heat transfer behaviors in the channel mounted with the 45° Z-Baffles, and the numerical results are found in good agreement with experimental data.
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3d simulation of laminar flow and heat transfer in v Baffled square channel
International Communications in Heat and Mass Transfer, 2012Co-Authors: Pongjet Promvonge, Sutapat Kwankaomeng, Chinaruk ThianpongAbstract:Abstract The article presents a numerical investigation on laminar flow and heat transfer characteristics in a three-dimensional isothermal wall square-channel fitted with inline 45° V-shaped Baffles on two opposite walls. The computations based on the finite volume method with the SIMPLE algorithm have been conducted for the airflow in terms of Reynolds numbers ranging from 200 to 2000. The inline V-Baffles with its V-tip pointing downstream and the attack angle (or half V-apex angle) of 45° relative to the flow direction are mounted repeatedly on the lower and upper walls. The Baffled channel flow shows a fully developed periodic flow and heat transfer profile for BR = 0.2 at x/D≈ 8 downstream of the inlet. Influences of different Baffle height ratios (BR) and pitch ratios, (PR) on thermal behaviors for a fully developed periodic condition are investigated. It is apparent that the longitudinal counter-rotating vortex flows created by the V-Baffle can induce impingement/attachment flows over the walls resulting in greater increase in heat transfer over the test channel. Apart from speeding up the fully developed periodic flow pattern, the rise of the BR leads to the increase in Nu/Nu0 and f/f0 values while that of the PR provides an opposite trend. The V-Baffle performs better than the angled Baffle at a similar condition. The V-Baffle with BR = 0.2 and PR = 1.5 yields the maximum thermal performance of about 3.8 whereas the Nu/Nu0 is some 14 times above the smooth channel at higher Re.
Shamsoddin Ghiami - One of the best experts on this subject based on the ideXlab platform.
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comparative study based on energy and exergy analyses of a Baffled solar air heater with latent storage collector
Applied Thermal Engineering, 2017Co-Authors: Amir Ghiami, Shamsoddin GhiamiAbstract:Abstract In this empirical study, exergy and energy investigation of a novel solar air heater (SAH) was undertaken in presence of the paraffin wax slab as the Phase-Change-Material (PCM). Characteristics of the system was scrutinized in presence and absence of Baffle on the absorber plate. In the experimental study, two types of Baffle-equipped and an unequipped absorber plate were inspected in presence of PCM unit and their exergy and efficiency were compared. For the Baffled absorber plates, the Baffles are made of galvanized plates and are arranged in sequential or staggered manner. At three different air mass flow rates of 0.017 Kg / s , 0.014 Kg / s and 0.009 Kg / s , inlet, PCM and outlet temperature were measured and compared. Exploiting the 1st and 2nd thermodynamics laws, the exergy and energy efficiencies were calculated. This study’s outcome approved that, at different air mass flow rates, the Baffle-equipped SAH obtained the highest efficiencies while the unequipped one has the lowest. It has been found out that, at the mass flow rate of 0.017 Kg / s , the maximum energy efficiency was attained for sequence-arranged Baffle-equipped SAH (26.78%), while unequipped SAH had the least energy efficiency (14.30%) at the same mass flow rate. The exergy efficiencies varied between 4.86 - 20.47 % for all cases of study.
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comparative study based on energy and exergy analyses of a Baffled solar air heater with latent storage collector
Applied Thermal Engineering, 2017Co-Authors: Amir Ghiami, Shamsoddin GhiamiAbstract:Abstract In this empirical study, exergy and energy investigation of a novel solar air heater (SAH) was undertaken in presence of the paraffin wax slab as the Phase-Change-Material (PCM). Characteristics of the system was scrutinized in presence and absence of Baffle on the absorber plate. In the experimental study, two types of Baffle-equipped and an unequipped absorber plate were inspected in presence of PCM unit and their exergy and efficiency were compared. For the Baffled absorber plates, the Baffles are made of galvanized plates and are arranged in sequential or staggered manner. At three different air mass flow rates of 0.017 Kg / s , 0.014 Kg / s and 0.009 Kg / s , inlet, PCM and outlet temperature were measured and compared. Exploiting the 1st and 2nd thermodynamics laws, the exergy and energy efficiencies were calculated. This study’s outcome approved that, at different air mass flow rates, the Baffle-equipped SAH obtained the highest efficiencies while the unequipped one has the lowest. It has been found out that, at the mass flow rate of 0.017 Kg / s , the maximum energy efficiency was attained for sequence-arranged Baffle-equipped SAH (26.78%), while unequipped SAH had the least energy efficiency (14.30%) at the same mass flow rate. The exergy efficiencies varied between 4.86 - 20.47 % for all cases of study.
Adam Harvey - One of the best experts on this subject based on the ideXlab platform.
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mass transfer enhancement as a function of oscillatory Baffled reactor design
Chemical Engineering and Processing, 2018Co-Authors: Safaa M R Ahmed, Anh N Phan, Adam HarveyAbstract:Abstract Air-water two-phase flow regimes were identified quantitatively and qualitatively for four designs of oscillatory Baffled reactor (OBR) over a range of oscillation conditions in semi-batch mode operation (continuous gas phase; batch liquid phase). The Baffle designs assessed were helical Baffles, smooth periodic constrictions, single orifice plate Baffles and multi-orifice plate Baffles. Oscillation in a smooth-walled tube was also characterised for comparison purposes. The designs were characterised over a range of oscillatory Reynolds number (Reo = 0–8000) and aeration rates, vvm = 0–1. All the reactors had the same geometrical parameters such as diameter, ratio of length to diameter etc. Three distinct flow regimes (bubbly flow, slug flow, and churn flow) were identified, which were similar to those found in conventional bubble columns (BCs), but the bubbly flow regime, which exhibits the highest rates of mass transfer, was observed over a wider range of oscillatory liquid velocities in OBRs. This was due to the flow patterns (usually vortices) and shear engendered by the interactions of the oscillatory flows and the Baffle designs, which resulted in coalescence and breakage of the bubbles. The volumetric mass transfer coefficients, kLa, were significantly increased in the multi-orifice design, up to 7-fold, compared with that for a steady flow (no oscillatory flow) in a smooth tube (unBaffled column).
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potential uses of oscillatory Baffled reactors for biofuel production
Biofuels, 2010Co-Authors: Nasratun Masngut, Adam Harvey, Joseph IkwebeAbstract:The oscillatory Baffled reactor (OBR) is a unique design of plug flow reactor consisting of a tube or column fitted with a series of Baffle plates. The key feature of OBRs is the combination of a periodic geometry (usually sharp-edged Baffles) and a periodically reversing flow in a tube or column. The OBR design may be suitable for production of various liquid biofuel, as the reactor‘s niche application is the performance of long residence time processes continuously in plug flow. A further advantage for biobutanol and bioethanol production could be that OBRs provide relatively low-shear uniform mixing, thereby achieving homogenous conditions in fermentation, without causing cell damage. Biodiesel production benefits from significantly reduced residence time (compared with batch production) and lower length-to-diameter ratio than equivalent conventional plug flow reactors, for example, the reactor is much more compact. This article reviews the possibility of the use of OBRs in three types of liquid biofue...
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development and evaluation of novel designs of continuous mesoscale oscillatory Baffled reactors
Chemical Engineering Journal, 2010Co-Authors: Anh N Phan, Adam HarveyAbstract:Abstract Oscillatory Baffled reactors (OBRs) are a form of plug flow reactor, ideal for performing long reactions in continuous mode, as the mixing is independent of net flow rate leading to more compact and practical designs. Mesoscale OBRs are currently being developed for laboratory-scale processes. The systems are designed to scale-up to industrial scale directly, or to be used as small-scale production platforms in their own right. Three different meso-reactor Baffle designs (integral Baffles, helical Baffles and axial circular Baffles (or “central”) Baffles) were developed. These designs were chosen, as they are easily fabricated at “mesoscales” (here typically ∼5 mm diameter) and can be operated at low flow rates (μl/min to ml/min), whereas conventional designs of OBRs cannot. It was found that an increase in the net flow Reynolds number increased the optimum range of oscillatory Reynolds numbers over which plug flow can be achieved. The oscillation conditions had little effect on the residence time distribution behaviour at net flow Reynolds numbers above 25. These designs are effective and robust in scaled-down production of high added value products and decreasing the reagents required.
