Different Types Of Packing Research Articles

Solvents regulate the packing porosity of a bilayer metal-organic cage.

Metal-organic cages (MOCs) are an emerging class of porous materials with promising applications. However, controlling the configuration of the cage packing, which can influence the overall porosity of the materials, remains a difficulty, as many factors can influence the cage assembly and stacking. Herein, we report a solvent strategy to fine-tune the packing configuration of a bilayer MOC, a small triangular prism cage (six Cu ions act as vertices, three nitrate ions act as pillars, and six nitrate ions act as caps) incorporated into a large triangular prism cage (another six Cu ions act as vertices, a couple of oxygen atoms act as pillars and six ligands (L1: 3,5-bis(pyridine-3-yl)-4H-1,2,4-triazole) act as a jointed cap) by the coordination between the triazole nitrogen from L1 and the inner vertex Cu ions. The involved solvents water, acetonitrile (MeCN) and N,N'-dimethylformamide (DMF) form hydrogen bonds with this bilayer MOC, resulting in three different types of packing associated with systemically tuned porosity (NTU-93: 12.2%, NTU-94: 19.3%, and NTU-95: 42.1%). Gas adsorption and breakthrough tests demonstrate that NTU-95 has potential ability for C2H2/C2H4 separation. This work not only shows a case of finely tuned packing of coordination cages, but also provides a powerful tool that may be extended to other cage families.

Steady-State Transitions in Ordered Porous Media

Previously performed experiments on flow through an ordered porous media cell with tomographic particle image velocimetry reveal a complex three-dimensional steady-state flow pattern. This flow pattern emerge in the region where inertial structures have been previously reported for a wide range of packings. The onset of these steady-state inertial flow structures is here scrutinized for three different types of packing using a finite difference method. It is concluded that the onset of the flow structure coincides with a symmetry break in the flow field and discontinuities in the pressure drop, volume averaged body forces and heat transfer. A quantity for identifying the transition is proposed, namely the pressure integral across the solid surfaces. It is also shown that the transition can both increase and decrease the heat transfer dependent on the actual geometry of the porous medium.

Estimation of vegetable leather shelf life from a combination of beluntas leaves (Pluchea indica L.) and seaweed (Eucheuma cottonii) with various types of packaging using the ASLT (accelerated shelf life testing) method of the arrhenius model

Beluntas leaves vegetable leather is a new processed product, so its shelf life is currently unknown. This research utilised the ASLT (Accelerated Shelf Life Test) Arrhenius model to assess the shelf life of vegetable leather in three different forms of packaging, including aluminum foil, combination (aluminum foil-polyethylene), and polypropylene. The research includes two replications and a descriptive design. Three different types of packing were used to store vegetable leather for a month at oven temperatures of 30°C, 35°C, and 40°C (28 days). Every week, on days 0, 7, 14, 21, and 28, observations were made about the moisture content and sensory factors (texture, color, and aroma). The shelf life of vegetable leather was calculated using the parameter data using the Arrhenius model ASLT method with Microsoft Excel 2010. The results indicated that vegetable leather beluntas leaves packaged in aluminum foil had a shelf life of 179.53 days (5 months, 27 days), while in combination packaging (aluminum foil-polyethylene), they had a shelf life of 44.20 days (1 month, 13 days). In polypropylene packaging, the product had a shelf life of 35.94 days (1 month and four days) according to order 1 of the Arrhenius model ASLT method.

Experimental study of direct contact condensation of spent vapor in a cocurrent flow packed tower under negative pressure

AbstractCondensers are often required in power generation systems to condense the exhaust steam generated at the end of the turbine. This paper will investigate the enhanced condensation process of spent steam in a parallel flow type. The operating parameters of steam temperature (Tcond), steam flow rate (Gin), cooling water temperature (Tin), and cooling water flow rate (Lw) will affect the condensation effect by changing the gas–liquid arrangement in the tower. In this experiment, an orthogonal test was designed in the Raschig ring to investigate the significance of these four operating parameters on the experimental results. Different types of packings have different condensation effects due to different accumulation methods. The same type of packing has a different surface area, resulting in different contact areas between the gas and liquid phases during condensation. In this experiment, four different packings will be investigated to find their condensation performance. This paper uses the size of subcooling (ΔT) as an indicator to evaluate the effectiveness of condensation, and the values of condensation rate (R), number of liquid phase heat transfer units (NTUL), and total volume heat transfer coefficient (Kv) are used as a reference for the effectiveness of condensation. The results show that the overall condensation effect of regular packing is better than that of random packing, The average condensation rate of regular packing is 95%, the average condensation rate of random packing is 90%, the subcooling of regular packing is about three to five smaller than that of random packing, the heat transfer coefficient of regular packing is about 1.5 times of that of random packing. And by fitting the Kv data for different packings, an empirical formula was obtained that can be used to predict the Kv size of other packings.

Chemical Looping Combustion in a Packed Fluidized Bed Reactor─Fundamental Modeling and Batch Experiments with Random Metal Packings

The conversion of gaseous fuels during chemical looping combustion (CLC) was investigated in a packed fluidized reactor. The experimental setup consisted of a cylindrical laboratory-scale bubbling fluidized bed reactor with an inner diameter of 78 mm and a height of 1.27 m. Two types of fuel, syngas (50:50% H2/CO) and carbon monoxide (100% CO), were used. Two different types of packings were assessed and compared to the reference case, which was a bubbling bed with no packings. The investigated packings were 25 mm stainless-steel thread saddle rings (RMSR) with a bulk density of 195 kg/m3 and 25 mm stainless-steel pall rings (Hiflow) with a bulk density of 271 kg/m3. The height of the packed reactor section was kept constant at 1 m. Ilmenite concentrate particles in the size range of 90–212 μm was used as an oxygen carrier. The unfluidized bed height was varied between 10 and 60 cm. The results show that the fuel conversion increases as the bed height increases and that the use of packings have a positive effect on fuel conversion. For RMSR packings, the syngas conversion at 840 °C improves from 0.84 (for 10 cm bed height) to 1.00 (for 60 cm bed height). This should be compared to the bed with no packings, for which the corresponding improvement was from 0.69 to 0.98. The general pattern is consistent for all fuels, packings, and bed heights. The results are interpreted as an improvement in gas–solid mass transfer when packings are used, mainly as a result of the reduced bubble size. A fundamental analysis of the variance in the pressure drop over the bed to estimate the bubble diameter supports this interpretation. It is also shown that the mass-based first-order effective reaction contact factor kf improves up to 109% in the bed with RMSR packings compared to the bed without packings.

Experimental Investigation of the Effect of Random Packings on Heat Transfer and Particle Segregation in Packed-Fluidized Bed

The heat transfer coefficient, pressure drop, and vertical segregation in a bubbling fluidized bed reactor containing random packings were investigated. The bed material was silica sand in the size range of 90–400 μm. Experiments were done for bed temperatures ranging from 400 to 900 °C and superficial gas velocities up to 0.411 m/s. Five different types of packings were evaluated: (i) RMSR (25 mm stainless steel thread saddle ring), (ii) Hiflow (25 mm stainless steel pall ring), (iii) RR6 (6 mm ceramic Raschig ring), (iv) RR10 (10 mm ceramic Raschig ring), and (v) ASB (12.7 mm aluminum silicate balls). The RMSR packing showed an increase in the heat transfer coefficient (up to 1243 W/m2K), as compared to bubbling beds with no packings (up to 1124 W/m2K). Also, beds with RMSR and Hiflow packings had a lower pressure drop and vertical segregation compared to low void factor packings such as RR6, RR10, and ASB.

Hydrodynamic Dispersion in Porous Media and the Significance of Lagrangian Time and Space Scales

Transport in porous media is critical for many applications in the environment and in the chemical process industry. A key parameter for modeling this transport is the hydrodynamic dispersion coefficient for particles and scalars in a porous medium, which has been found to depend on properties of the medium structure, on the dispersing compound, and on the flow field characteristics. Previous studies have resulted in suggestions of different equation forms, showing the relationship between the hydrodynamic dispersion coefficient for various types of porous media in various flow regimes and the Peclet number. The Peclet number is calculated based on a Eulerian length scale, such as the diameter of the spheres in packed beds, or the pore diameter. However, the nature of hydrodynamic dispersion is Lagrangian, and it should take the molecular diffusion effects, as well as the convection effects, into account. This work shifts attention to the Lagrangian time and length scales for the definition of the Peclet number. It is focused on the dependence of the longitudinal hydrodynamic dispersion coefficient on the effective Lagrangian Peclet number by using a Lagrangian length scale and the effective molecular diffusivity. The lattice Boltzmann method (LBM) was employed to simulate flow in porous media that were constituted by packed spheres, and Lagrangian particle tracking (LPT) was used to track the movement of individual dispersing particles. It was found that the hydrodynamic dispersion coefficient linearly depends on the effective Lagrangian Peclet number for packed beds with different types of packing. This linear equation describing the dependence of the dispersion coefficient on the effective Lagrangian Peclet number is both simpler and more accurate than the one formed using the effective Eulerian Peclet number. In addition, the slope of the line is a characteristic coefficient for a given medium.

Effect of magnetic field on a loosely packed, tightly packed and an over-tightly packed metal powder bed

The effect of alternating magnetic field on the pressure drop inside a fixed bed with different types of packing is experimentally investigated. The bed was packed with three different masses of iron(III)oxide powder as a loosely packed, tightly packed and an over tightly packed bed system. A Helmholtz coil was used to apply an AC magnetic field (60 Hz) and the pressure drop measurements were made for a range of flowrates between 29 SCFM to 25 SCFM at a small deceleration of 0.03 in/s2 (0.001 m/s2). The magnetic field was applied continuously throughout the time of pressure-drop measurements, and also was turned off before the measurements began to analyze the behavior of the bed. It was found that in a loosely packed bed system, the pressure drop decreased for all magnetic field orientations compared to the no magnetic field configuration, whereas in the tightly packed bed samples, the pressure drop values can be increased or decreased by altering the magnetic field orientation. In the tightly packed bed samples, the pressure drop values did not alter when the magnetic field was turned off during the flow and is only needed until the flow enters the bed.

Heat and Mass Transfer Characteristics and Energy Characteristics of the Packing of Column Apparatuses

Comparative characteristics of different packed contact devices are determined. Computational data on the energy complex for estimating the energy-efficiency of irregular and regular heat and mass-transfer packing are presented. Calculation of the heat and mass-transfer coefficients is performed using the equations of a mathematical model for corresponding designs of regular and irregular types packing. Both empirical expressions and experimental data are used in calculating the hydraulic resistance. Comparative characteristics of mass-transfer columns with different types of packing are presented and more efficient designs of packing are created.

Liquid distributor design for random packed columns

Liquid distributors are the second most important internal in packed columns, as they ensure sufficient initial distribution, which is crucial to achieve optimum separation performance. In this work, a liquid distributor design method is presented, which applies the TUM–WelChem Cell Model to consider the interaction between the liquid distributor and the packing. Liquid distribution in the packing is estimated in dependence of the liquid distributor design. An overall maldistribution quality is determined as a characteristic value for evaluation. Two common methods, the coefficient of variation and the liquid distribution quality by Moore and Rukovena, are implemented for reference. A parameter study with an exemplary column design provides optimum drip point densities for different types of packing. Moreover, the spacing between the outermost drip points and the column wall is considered in detail, suggesting an optimum distribution quality for high wall spacing. Further application of the method suggests an increase of the optimum drip point density for smaller column diameters. Application of the TUM–WelChem Cell Model to liquid distributor design provides a potent tool for an optimized distributor layout with sufficient initial distribution at minimized material usage and high free space for the gas flow.

Experimental Study of the parameters Affect on the Thermal Performance of Cooling Tower

Cooling tower is a type of direct contact heat exchanger, inside of which heat is withdrawn from water to air. In this research experimental study of the performance of forced draft counter flow cooling tower at different conditions and different operating parameters. The study was conducted for different water inlet temperature, different water flow rate, different air flow rate, differentinjection holes diameter, different interval distance between injection holes and different types of packing. The results obtained indicate an increase cooling tower efficiency with the increase of water inlet temperature, air flow rate, interval distance between injection holes while it is decreased with the increase of injection holes diameter and water flow rate. The packing of metal mesh has highest efficiency. The efficiency of cooling tower with metal packing is higher than that with plastic cells by 5.6%, with that of Kraft paper by 40.4% and with the case of no packing by 51.8 %. However, the packing metal mesh is highest in pressure drop of other the types.

Effect of tilt on mass transfer and hydrodynamic performance in a packing column

To investigate the working performance of packing columns used in offshore floating production, CO2-absorption and hydrodynamic experiments were performed in a tilted laboratory-scale packing column. A six-degree-of-freedom motion parallel platform was adopted to mimic different tilted states (3°–12°). Using a CO2–NaOH system, the effects of the liquid flow rate (6–24m3/m2/h), NaOH concentration (0.5–2mol/L), gas flow rate (4.1–8.0m3/h) and CO2 molar fraction at the inlet (4.0–7.5%) on the CO2 absorption performance were investigated under normal pressure and temperature conditions. Liquid hold-up and pressure drop were measured using a water–air system. Three different types of packing were tested to compare their anti-tilt performance. The experimental results showed that tilt significantly reduced the mass transfer performance of Pall Ring 10mm; however, the reductions in the performance of Sulzer BX500 and BY500 were minor. Further, both liquid holdup and pressure drop of three packings were reduced by tilt.

Effect of the Tower Type on the Gas Sweetening Process

The removal of acid gases, CO2 and H2 S from natural gas streams is essential for environmental and health reasons. In this work, the simulated gas sweetening unit with Methyl-DiEthanolAmine (MDEA) solvent was studied to improve quality. Firstly, the effect of trays types and then, the effect of various packing and the effect of the packing size were considered on the flow rate of CO2 and H2 S in the main streams. Results show that with considering the different trays types in the regenerator tower, the flow rate of CO2 in the sweet gas stream with bubble cap tray is lower than other trays types. Also, with considering the different trays types in the absorber tower, the flow rate of CO2 in the sweet gas stream with bubble cap tray is lower than other trays types in the absorber tower. In considering with different types of packing, results show that the flow rate of CO2 with ballast ring packing and the flow rate of H2 S with Raschig ring packing are lower than other types of packing. However, in some types such as cascade miniring, Intalox Saddles and pall ring, there is no difference for the flow rate of CO2 or H2 S. In all cases, with increasing the size of the packing, the flow rate of CO2 and H2 S in the sweet gas stream increases, however, this increasing in the metal packing is very small.

Investigation of holdup and axial dispersion of liquid phase in a catalytic exchange column using radiotracer technique

Holdup and axial dispersion of liquid phase in a catalytic exchange column were investigated by measuring residence time distributions (RTD) using a radiotracer technique. RTD experiments were independently carried out with two different types of packings i.e. hydrophobic water-repellent supported platinum catalyst and a mixture (50% (v/v)) of hydrophobic catalyst and a hydrophillic wettable packing were used in the column. Mean residence times and hold-ups of the liquid phase were estimated at different operating conditions. Axial dispersion model (ADM) and axial dispersion with exchange model (ADEM) were used to simulate the measured RTD data. Both the models were found equally suitable to describe the measured data. The degree of axial mixing was estimated in terms of Peclet number (Pe) and Bodenstein number (Bo). Based on the obtained parameters of the ADM, correlations for total liquid hold-up (HT) and axial mixing in terms of Bo were proposed for design and scale up of the full-scale catalytic exchange column.

Extraction of force-chain network architecture in granular materials using community detection.

Force chains form heterogeneous physical structures that can constrain the mechanical stability and acoustic transmission of granular media. However, despite their relevance for predicting bulk properties of materials, there is no agreement on a quantitative description of force chains. Consequently, it is difficult to compare the force-chain structures in different materials or experimental conditions. To address this challenge, we treat granular materials as spatially-embedded networks in which the nodes (particles) are connected by weighted edges that represent contact forces. We use techniques from community detection, which is a type of clustering, to find sets of closely connected particles. By using a geographical null model that is constrained by the particles' contact network, we extract chain-like structures that are reminiscent of force chains. We propose three diagnostics to measure these chain-like structures, and we demonstrate the utility of these diagnostics for identifying and characterizing classes of force-chain network architectures in various materials. To illustrate our methods, we describe how force-chain architecture depends on pressure for two very different types of packings: (1) ones derived from laboratory experiments and (2) ones derived from idealized, numerically-generated frictionless packings. By resolving individual force chains, we quantify statistical properties of force-chain shape and strength, which are potentially crucial diagnostics of bulk properties (including material stability). These methods facilitate quantitative comparisons between different particulate systems, regardless of whether they are measured experimentally or numerically.

Optimization of cooling tower performance with different types of packings using Taguchi approach

This study discuss the application of Taguchi method in assessing maximum cooling tower effectiveness for the counter flow cooling tower using different types of packing. The experiments were planned based on Taguchi’s L9 orthogonal array. The trial was performed under different conditions of liquid-to-gas flow ratio, inlet water temperature and packing materials. Signal-to-noise ratio analysis, analysis of variance and regression were carried out in order to determine the effects of process parameters on cooling tower effectiveness and to identify optimal factor settings. Finally, confirmation tests verified the reliability of Taguchi method for optimization of counter flow cooling tower performance with sufficient accuracy.

Mass and Heat Transfer in a Batch Bubble Column Operating with and without Packing

In this work, the transfer coefficients of mass and heat (by analogy) at a vertical cylinder centered in a bubble column were studied experimentally in two cases: (i) freely bubbling liquid–gas and (ii) packed bubble column with plastic packing around the cylinder. The parameters studied are solution physical properties, cylinder height, packing geometry, size of packing, and gas flow rate. The presence of inert packing at the cylinder surface increased transfer rates of mass and heat (by analogy). The factor of this increase ranged from 1.46 to 2.73 times, based on the gas superficial velocity and the packing geometry. All data were correlated by dimensional analysis using the equation j = a(Re × Fr)b. The constants a and b in the dimensionless equations were determined experimentally for the unpacked column and for the packed column with different types of packing. Potential applications of the results in reactor design were discussed.

Orbital structure of vibrations of nanoparticles, clusters, and coordination polyhedra

The necessity of the development of the orbital structure of vibrations of nanoparticles, clusters, and coordination polyhedra is dictated by synthesis of clusters, supermolecules, and other structures of nanoscale dispersion for which translational symmetry is absent and the crystal system is inapplicable. The composition of complicated molecules, polynuclear complexes, and clusters is described, in addition to the chemical formula, by the composition equations derived from analysis of the symmetry properties of molecular structures. This analysis enables the derivation of analytical formulas for the types of molecular orbitals of structures with arbitrary groups of symmetry. Here, we use the representation of nanoscale structures described by the orbital system as a set of concentric nested spherical orbits of atoms, orbits of faces of different order, and orbits of edges. The orbits are grouped into shells shaped as polyhedra with vertices, edges, or faces accommodating atoms with different types of packing. In such a way, the sets of molecular orbitals of all high-, intermediate-, and low-symmetry groups have been determined depending on the number of atoms in the axial, planar, and primitive orbits.

Study on Biofilm Colonization in Different Types of Packing

To analysis the effect of different types of packing on the biofilm, combined packing, elastic packing and novel bamboo packing were selected as the testing packing in the contact oxidation tank and studied in the static condition. The indexes such as the total bacteria count and water quality changes were investigated to illustrate the characteristics of membrane and the effect of biofilm colonization in different membrane system.

Substrates for germination and physiological quality of storage seeds of Parapiptadenia rigida (Benth.) Brenan

"Angico-vermelho" [Parapiptadenia rigida (Benth.) Brenan] is an arboreal forestal species native from Brazil used for rural constructions, firewood, charcoal, and forest restoration programs; however it is little studied in regard to seed technology. Thus, the objective of this study was assessing different substrates for conducting tests of germination and physiological quality of seeds stored under different environments and packings for 420 days. Firstly, the most suitable substrate for the germination test was identified and subsequently the seeds were stored into three different types of packings (paper, plastic and glass) and three different environmental conditions (cold chamber, refrigerator and laboratory). Seed samples from each storage condition were removed at every 60 days for evaluating moisture content, germination and vigor (electrical conductivity test). A completely randomized experimental design was used with treatments arranged into a split-plot design for storage periods. It was found that the germination test can be conducted using between the sand as substrate, with the first count of emergence of seedlings performed at the fourth day and the final counting at 10 days after seeding. That seeds can be stored preferably in refrigerator into paper packings, although packings of plastic and/or glass are also suitable.