scholarly journals Gas-liquid flows through porous media in microgravity: Packed Bed Reactor Experiment-2

2021 ◽  
Author(s):  
Brian Motil ◽  
Mahsa Taghavi ◽  
Vemuri Balakotaiah ◽  
Henry Nahra
Keyword(s):  
Gas Flow ◽  
Liquid Velocity ◽  
Space Station ◽  
Particle Diameter ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Flow Rates ◽  
Test Conditions ◽  
Superficial Gas Velocity ◽  
Liquid Flows

Experimental results on pressure drop and gas hold-up for gas-liquid flow through packed beds obtained from a second flight on the International Space Station are presented and analyzed. It is found that the gas hold-up is a function of the bed history at low liquid and gas flow rates whereas higher gas hold-up and pressure gradients are observed for the test conditions following a liquid only pre-flow compared to the test conditions following a gas only pre-flow period. Over the range of flow rates tested, the capillary force is the dominant contributor to the pressure gradient and is found to be linear with the superficial liquid velocity but is a much weaker function of the superficial gas velocity. The capillary contribution is also a function of the particle size and varies approximately inversely with the particle diameter within the range of the test conditions.

scholarly journals Heat and Mass Transfer during Lignocellulosic Biomass Torrefaction: Contributions from the Major Components—Cellulose, Hemicellulose, and Lignin

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 959
Author(s):  
Ken-ichiro Tanoue ◽  
Kentaro Hikasa ◽  
Yuuki Hamaoka ◽  
Akihiro Yoshinaga ◽  
Tatsuo Nishimura ◽  
...  
Keyword(s):  
Gas Flow ◽  
Model Simulation ◽  
Packed Bed ◽  
Douglas Fir ◽  
Packed Bed Reactor ◽  
Reactor Wall ◽  
Measured Temperature ◽  
Reactor Performance ◽  
Rate Vector ◽  
Determining Factor

The torrefaction of three representative types of biomass—bamboo, and Douglas fir and its bark—was carried out in a cylindrical-shaped packed bed reactor under nitrogen flow at 573 K of the reactor wall temperature. As the thermal energy for the torrefaction was supplied from the top and the side of the bed, the propagation of the temperature profile of the bed is a crucial factor for discussing and improving the torrefaction reactor performance. Therefore, the temperature and gas flow rate (vector) profiles throughout the bed were calculated by model simulation so as to scrutinize this point. The measured temperature at a certain representative location (z = 30 mm and r = 38 mm) of the bed was well reproduced by the simulation. The volume faction of the bed at temperatures higher than 500 K at 75 min was 0.89, 0.85, and 0.99 for bamboo, and Douglas fir and its bark, respectively. It was found that the effective thermal conductivity is the determining factor for this difference. The heat of the reactions was found to be insignificant.

Liquid and Gas Phase Velocity Measurements for Two Phase Flow in a Branching Microchannel Network

2007 ◽  
Author(s):  
Younghoon Kwak ◽  
Deborah Pence ◽  
James Liburdy ◽  
Vinod Narayanan
Keyword(s):  
Liquid Velocity ◽  
Leading Edge ◽  
Velocity Measurements ◽  
Trailing Edge ◽  
Two Phase ◽  
Order Of Magnitude ◽  
Image Pairs ◽  
Superficial Gas Velocity ◽  
Liquid Flows ◽  
Velocity Deficits

This is a work in progress. The objective of the present work is to develop techniques for assessing velocity deficits in branching microchannel networks. Liquid velocity distributions were acquired using μPIV in gas-liquid flows through the initial branch in a fractal-like branching microchannel flow network. Gas interface velocities were determined along the centerline of the channel. The flow rate of air and water were 0.0016 g/min and 20 g/min, respectively. The primary observed flow regime was elongated bubbles. Experimental liquid velocities well matched the 0.20 m/s superficial liquid velocity. Experimental interface velocities were approximately an order of magnitude higher than the superficial gas velocity of 0.01 m/s. Velocity deficits based on measurements are on the order of 0.065 m/s. Using interfacial velocities at the channel centerline, the trailing edge velocity was observed to be 15% percent faster, on average, than the leading edge velocity. This could be attributed to bubbles expanding into the bifurcation. Twenty percent standard deviations in average interface velocities were attributed to insufficient samples as well as projected to be a consequence of changing shape of the interface between consecutive image pairs. Changes in bubble shape may also be responsible for the observed differences between leading and trailing edge velocities.

scholarly journals WALL EFFECT OF A PACKED BED WITH PELLET PARTICLES

2018 ◽  
Vol 56 (2A) ◽  
pp. 31-36
Author(s):  
Tran Duy Hai
Keyword(s):  
Flow Rate ◽  
Particle Diameter ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Radial Coordinate ◽  
Flow Profile ◽  
Local Velocity ◽  
Gas Velocity ◽  
Bed Height ◽  
Small Ratio

Fluid flow profile is a dominate role in the performance of packed bed reactor. In small ratio of column-to-particle diameter, velocity pattern is strongly affected by voidage distribution, which depends on radial coordinate, flow rate and bed height. In this study, effects of voidage distribution to gas velocity profile in a packed bed with pellet particles was empirically investigated. Uniformity of local velocity at the top of the bed was clearly observed with decreasing of bed height and flow rate. For 400 mm of bed height, the measured velocities are a well fitting to Fahien and Stankovich model for any expected flow rate.

scholarly journals Influence of liquid and gas flow rates on sulfuric acid mist removal from air by packed bed tower

2012 ◽  
Vol 9 (1) ◽  
Author(s):  
Mohammad Javad Jafari ◽  
Roohollah Ghasemi ◽  
Yadollah Mehrabi ◽  
Reza Ahmad Yazdanbakhsh ◽  
Majid Hajibabaei
Keyword(s):  
Sulfuric Acid ◽  
Gas Flow ◽  
Packed Bed ◽  
Flow Rates ◽  
Acid Mist

Simultaneous Absorption of SO2 and NO Using Sodium Chlorate/Urea Absorbent in a Rotating Packed Bed

2014 ◽  
Vol 908 ◽  
pp. 187-190
Author(s):  
Mei Jin ◽  
Guo Xian Yu ◽  
Fang Wang ◽  
Ping Lu
Keyword(s):  
Removal Efficiency ◽  
Flow Rate ◽  
Flue Gas ◽  
Gas Flow ◽  
Packed Bed ◽  
Sodium Chlorate ◽  
Experimental Conditions ◽  
Flow Rates ◽  
Simultaneous Absorption ◽  
Rotating Packed Bed

In this work, simultaneous absorption of SO2and NO from N2-NO-SO2simulated flue gas using sodium chlorate as the additive and urea as the reductant was investigated experimentally in a rotating packed bed. In RPB, various rotational speeds, gas flow rates and liquid flow rates were studied by means of the removal efficiency of SO2and NO. The experimental results showed that the removal efficiency of SO2was higher than 99.00% under various experimental conditions and, at the same time, the removal efficiency of NO exhibited different results under various experimental conditions. The simultaneous NO removal efficiency of 82.45% and the SO2removal efficiency of 99.49% could be obtained under the N2flow rate of 0.5 m3/h, SO2flow rate of 6 mL/min, the NO flow rate of 4 mL/min, the rotational speed of 460 rpm and the absorbent flow rate of 40 L/h.

Augmentation of the Performance of Batch Electrocoagulation Unit by Using Gas Sparging

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Ahmed Hassan Elshazly
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Dye Removal ◽  
Gas Velocity ◽  
Gas Flow Rate ◽  
Flow Rates ◽  
Gas Sparging ◽  
Current Densities ◽  
Superficial Gas Velocity ◽  
Time Of Operation

The present work investigates the effect of gas sparging in improving the performance of a batch electrocoagulation unit used to treat wastewater generated from the dyeing industry. Monopolar cylindrical aluminum electrodes were used. Many variables were investigated such as superficial gas velocity, current density, initial dye concentration, area ratio (cathode/anode), time of operation and the effect of adding chemical coagulant as FeSO4. The results show that the percentage of dye removal has been increased by a factor ranging from 2.52 to 5.14 by increasing the gas flow rate from 0.4 to 0.8 liter/min respectively and that about 93.5 percent of the dye can be removed within 60 minutes. Also it was found that using gas sparging is more efficient than adding chemical coagulant as ferrous sulfate for the removal of dye from wastewater. The power consumption for the unit was measured for different gas flow rates and different current densities; the results show that lower gas flow rate can improve the economy of the process.

scholarly journals Hydrodynamic characteristics of a two-phase gas-liquid flow upward through a fixed bed of spherical particles

2001 ◽  
Vol 66 (1) ◽  
pp. 53-64 ◽  
Author(s):  
Snezana Serbula ◽  
Velizar Stankovic
Keyword(s):  
Pressure Drop ◽  
Liquid Velocity ◽  
Fixed Bed ◽  
Particle Diameter ◽  
Packed Bed ◽  
Spherical Particles ◽  
Hydrodynamic Characteristics ◽  
Phase System ◽  
Relative Pressure ◽  
Two Phase

The influence of an electrochemically generated gas phase on the hydrodynamic characteristics of a three-phase system has been examined. The two-phase fluid, (gas-liquid), in which the liquid phase is the continuous one, flows through a packed bed with glass spheres. The influence of the liquid velocity was examined, as well as the gas velocity and particle diameter on the pressure drop through the fixed bed. It was found that with increasing liquid velocity (wl = 0.0162-0.03 m/s), the relative pressure drop decreases through the fixed bed. With increasing current density, the pressure drop increases, since greater gas quantities stay behind in the fixed bed. Besides, it was found that with decreasing diameter of the glass particles, the relative pressure drop also decreases. The relationship betweeen the experimentally obtained friction factor and the Reynolds number was established.

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