Packing Volume Research Articles

Optimizing economic feasibility of CO2 capture processes with rotating packed bed (RPB): Strategies for scale and modularization

Rotating Packed Bed (RPB) technology is increasingly recognized in the field of carbon capture for its potential to broaden application scopes and significantly reduce capital expenditures by minimizing packing volume. However, the commercialization of RPB-based CO2 capture presents several challenges at the process level, including enhancing energy efficiency, refining equipment design, and achieving scalability. Given the mechanical constraints, designing excessively large RPB units may be impractical. Thus, the economic scalability of RPB-based CO2 capture under practical constraints remains an unresolved issue. This study explores the cost-optimal CO2 capture scale through rigorous process simulation using 30-70 wt% monoethanolamine (MEA) solvents. It optimizes the process design and operating parameters to minimize the specific CO2 avoidance costs, within the bounds of practical RPB design limitations. The findings suggest that a capture scale of 100–200 Tons Per Day (TPD) is cost-optimal when using 50 wt% MEA for flue gases with CO2 concentrations above 14.5 mol%. However, cost-effective RPB design becomes challenging at CO2 concentrations as low as 4 mol%. The analysis suggests that the optimal scale might increase with future advancements in RPB design technologies. Current design constraints necessitate a modular approach as the most economically viable strategy for scaling up RPB-based CO2 capture. This modularization strategy supports the wider adoption of CO2 capture technologies at small- to medium-scales, facilitating industry-wide implementation and sustainable progress by reducing initial investment and allowing for phased scaling.

Exploration of physical, structural, thermal, and optical properties of alkali zinc boro tellurite glasses doped with europium trioxide

In this present work we have studied the physical, structural, thermal, and optical properties of a new set of alkali zinc boro tellurite glasses doped europium trioxide prepared using the melt-quenching method. X-ray diffraction technique (XRD) and SEM were used to determine the non-crystalline property and microstructure property of the prepared samples. By using MAS-NMR spectroscopy and FTIR spectroscopy, the structural changes in the glasses were revealed. The physical properties were described by considering the densities of glass samples and hence molar volume, polaron radius, and oxygen packing density were measured. Thermal stability of glasses was perceived by performing DSC analysis and values ranges from 145 to 190 °C. Using UV–visible absorption spectra, it was possible to calculate the optical properties. The highest refractive index is found as 2.275 for glass AZBTE0 and the lowest is 2.241 for AZBTE5 glass. The ionic behaviour of the glasses was determined by electronegativity and values lie in the range of 1.51 to 1.688. The outcomes of the physical, thermal, and optical characteristics of glasses are intended for potential uses in optical switching and Europium doped fibre amplifier applications.

Novel Eu3+-Doped Glasses in the MoO3-WO3-La2O3-B2O3 System: Preparation, Structure and Photoluminescent Properties.

Novel multicomponent glasses with nominal compositions of (50-x)MoO3:xWO3:25La2O3:25B2O3, x = 0, 10, 20, 30, 40, 50 mol% doped with 3 mol % Eu2O3 were prepared using a conventional melt-quenching method. Their structure, thermal behavior and luminescent properties were investigated by Raman spectroscopy, differential thermal analysis and photoluminescence spectroscopy. The optical properties of the glasses were investigated by UV-vis absorption spectroscopy and a determination of the refractive index. Physical parameters such as density, molar volume, oxygen molar volume and oxygen packing density were determined. The glasses are characterized by a high glass transition temperature. Raman analysis revealed that the glass structure is built up mainly from tetrahedral (MoO4)2- and (WO4)2- units providing Raman bands of around 317 cm-1, 341-352 cm-1, 832-820 cm-1 and 928-935 cm-1. At the same time, with the replacement of MoO3 with WO3 some fraction of WO6 octahedra are produced, the number of which increases with the increasing WO3 content. A strong red emission from the 5D0 level of Eu3+ ions was registered under near-UV (397 nm) excitation using the 7F0 → 5L6 transition of Eu3+. Photoluminescence (PL) emission gradually increases with increasing WO3 content, evidencing that WO3 is a more appropriate component than MoO3. The integrated fluorescence intensity ratio R (5D0 → 7F2/5D0 → 7F1) was calculated to estimate the degree of asymmetry around the active ion, suggesting a location of Eu3+ in non-centrosymmetric sites. All findings suggest that the investigated glasses are potential candidates for red light-emitting phosphors.

Local volume concentration, packing domains, and scaling properties of chromatin

Local volume concentration, packing domains, and scaling properties of chromatin

Local volume concentration, packing domains, and scaling properties of chromatin.

We propose the Self Returning Excluded Volume (SR-EV) model for the structure of chromatin based on stochastic rules and physical interactions. The SR-EV rules of return generate conformationally defined domains observed by single-cell imaging techniques. From nucleosome to chromosome scales, the model captures the overall chromatin organization as a corrugated system, with dense and dilute regions alternating in a manner that resembles the mixing of two disordered bi-continuous phases. This particular organizational topology is a consequence of the multiplicity of interactions and processes occurring in the nuclei, and mimicked by the proposed return rules. Single configuration properties and ensemble averages show a robust agreement between theoretical and experimental results including chromatin volume concentration, contact probability, packing domain identification and size characterization, and packing scaling behavior. Model and experimental results suggest that there is an inherent chromatin organization regardless of the cell character and resistant to an external forcing such as RAD21 degradation.

On the Stabilizing Effect of Aspartate and Glutamate and Its Counteraction by Common Denaturants.

By performing differential scanning calorimetry(DSC) measurements on RNase A, we studied the stabilization provided by the addition of potassium aspartate(KAsp) or potassium glutamate (KGlu) and found that it leads to a significant increase in the denaturation temperature of the protein. The stabilization proves to be mainly entropic in origin. A counteraction of the stabilization provided by KAsp or KGlu is obtained by adding common denaturants such as urea, guanidinium chloride, or guanidinium thiocyanate. A rationalization of the experimental data is devised on the basis of a theoretical approach developed by one of the authors. The main contribution to the conformational stability of globular proteins comes from the gain in translational entropy of water and co-solute ions and/or molecules for the decrease in solvent-excluded volume associated with polypeptide folding (i.e., there is a large decrease in solvent-accessible surface area). The magnitude of this entropic contribution increases with the number density and volume packing density of the solution. The two destabilizing contributions come from the conformational entropy of the chain, which should not depend significantly on the presence of co-solutes, and from the direct energetic interactions between co-solutes and the protein surface in both the native and denatured states. It is the magnitude of the latter that discriminates between stabilizing and destabilizing agents.

Investigation of Effects of Spreading Parameters on Powder Bed Quality in Additive Manufacturing

Powder bed-based additive manufacturing processes such as laser powder bed fusion, binder jetting, and electron beam melting are commonly utilized in various critical areas such as medical, aviation, and energy. Common to all these operations, the powders are first spread onto the built platform in a layer-by-layer fashion and selectively fused or bound with a suitable method. The quality of the process depends on several process parameters, including how the powders are spread onto the built platform. Powder spreading is an important step in these operations and can affect various process outputs. In this study, the powder spreading is numerically investigated using the discrete element method to determine the effects of the layer thickness, rotation, and transition velocities selected as parameters with a powder spreader roller. The relationship between powder spreading parameters and powder volume packing fraction was investigated using the 'Hertz-Mindlin and Johnson-Kendall-Robert’s (JKR) contact model considering the interactions between particle-particle and particle-built plate, has been added to the numerical model. A Design of Experiment combined with analysis of variance (ANOVA) was utilized to gain a broader understanding on the relationship between process parameters and green density and dynamic angle of repose.

Transportation Vibration Effects on Apple Bruising

ABSTRACTVibrations during transportation often cause mechanical damage to fresh produce. Addressing or mitigating this damage requires efficient packaging solutions that maintain fresh produce integrity during transit, thereby preserving produce quality and market value. This study investigates the effects of various transportation profiles and packaging designs on apple bruising using simulated truck vibrations. Two apple varieties, Fuji and Jonagold, were packaged in corrugated paperboard boxes with paper pulp trays, plastic crates with paper pulp trays, corrugated paperboard boxes with volume packing and plastic crates with volume packing, all commercial apple packaging. The packaged apples were exposed to two random vibration profiles: leaf spring and air ride suspensions, both set at four different intensities ranging from 0.2 to 0.7 Grms for 1, 3 and 5 h. The findings revealed that both packaging type and vibration parameters significantly influenced apple bruising. Especially, plastic crates with paper pulp trays led to the most severe bruising, whereas corrugated paperboard boxes with volume packing afforded the most protection. Regardless of the packaging design, leaf spring suspension resulted in more apple bruising compared to air ride suspension. The findings of this study provide practical insights for packaging engineers to mitigate the apple bruising during transportation.

Peri-operative management of endoscopic endonasal cerebrospinal fluid leak repair: an international survey.

Peri-operative management of nasal cerebrospinal fluid (CSF) leaks is not consensual due to limited evidence. The main aim of this study was to identify key factors in peri-operative management of endoscopic endonasal CSF leak repair among international experts. A 60-item survey questionnaire collected opinions of members of international learned societies of ENT surgeons and neurosurgeons on nasal packing, post-operative instructions, antibiotic prophylaxis, and CSF volume depletion. The survey had 153 respondents (124 otorhinolaryngologists and 29 neurosurgeons). A resting position was recommended by 85% (130/151) of respondents for extended CSF leak of the anterior skull base, mainly in Fowler's position (72% (110/153)). Nasal packing was used by 85% (130/153) of respondents; 33.3% (51/153) used it to stabilize the reconstruction, and 22.2% (34/153) to prevent bleeding. It was usually removed after 48h in 44.4% of cases (68/153). CSF depletion was considered by 47.1% (72/153) of respondents in case of CSF leak recurrence and by 34.6% (53/153) in cases of increased intracranial pressure. All respondents gave specific postoperative instructions to patients including driving, running, swimming, diving restrictions and flighting restrictions. In subgroup analysis, ENT surgeons more often recommended a resting position than neurosurgeons (71% vs. 37.9% ; p = 0.0008) and prescribed more antibiotics (82.3% vs. 21.4% ; p < 0.0001). Although postoperative management after CSF closure remains challenging and not codified, this international survey revealed some points of consensus concerning resting position and restriction of post-operative activities. Prospective clinical studies must be undertaken to evaluate their efficiency.

Preparation and characterization of strontium-doped bismuth borate glasses

Employing the melt quenching method, new bismuth borate glass compositions denoted as (40+x)Bi2O3–(60-x-y)B2O3–ySrO, with x and y ranging between 0 to 20 mol%, were synthesized. The X-ray Diffraction analyses confirmed the amorphous nature of all glass samples, indicating the absence of long-range order typically seen in crystalline materials. Concurrently, the Fourier-transform Infrared Spectroscopy examinations unveiled the existence of fundamental structural units within the glasses, including BO3 and BO4 trigonal and tetrahedral units, as well as BiO3 and BiO6 polyhedra, suggesting a complex network structure. Differential Thermal Analysis (DTA) and dilatometry assessed the glasses' thermal properties. DTA demonstrated the glasses' high thermal stability, with a stability value of up to 106°C, noting that stability improves with more SrO. Dilatometry analyses revealed these glasses exhibit a high thermal expansion coefficient, ranging from 8.69 to 10.7 ppm/°C, alongside relatively low glass transition temperatures between 362 and 432°C and dilatometric softening temperatures spanning from 380 to 447°C. Density measurements were conducted, followed by molar volume and oxygen packing density calculations, to glean further insights into the samples. Compared to other heavy-metal oxide glasses, the glasses examined in this study exhibited notably high-density values, ranging between 6.279 and 7.476 g/cm3 .

Investigation of structural, physical and optical properties of sodium boro-tellurite glasses doped with iron oxide

In this work, we demonstrate systematic studies on the influence of Fe2O3 on the structural and optical properties of transparent B2O3–TeO2–Na2O glasses containing the different concentrations of Fe2O3. The glasses were prepared via the standard melt quenching method, and the prepared glasses were characterized using, XRD, electron paramagnetic resonance (EPR), FTIR, and UV–visible spectroscopic techniques. Furthermore, we evaluated several physical properties of the glasses, including densities, molar volume, boron-boron separation, and oxygen packing density, with respect to the concentration of Fe2O3 in the host glass matrix. It is observed that the density of the glasses and the average boron-boron distance found increase with Fe2O3 concentration due to the modification in the glass network induced by the dopant ions. EPR spectra reveals the presence resonance signals at g ∼2.04 and g ∼4.26, hence it proves the existence of Fe3+ in distorted octahedral coordination and supported by UV–Vis absorption bands. The FTIR spectra revealed an increase in spectral intensity with the concentration of Fe2O3. This was attributed to the formation of non-bridging oxygens through converting BO4 units into BO3 units, which Fe2O3 mediated. The UV–visible spectral analysis showed a decreased energy band gap from 2.26 to 1.51 eV with increased Fe2O3 concentration. Additionally, we determined the Urbach energy, refractive index, optical basicity, and electronegativity, which are presented in detail.

The effect of zinc substitution on the optical properties of Sm3+ doped zinc borate glasses

Zinc borate glasses are a relatively well known glass type that can be produced at comparably low temperatures. Variations in both the type and concentration of network modifier atoms induce structural alterations within the glass matrix. If doped with optically active dopants, e.g. rare earth ions, compositional changes also affect the local surrounding of the dopants and consequently their optical properties such as emission peak shape and peak ratio. To investigate the effect of different low field strength network modifier ions in zinc borate glasses two glass series were prepared using the melt quench technique; Sm3+ was used as dopant ion: 50B2O3, xK2O, (49-x)ZnO, 1Sm2O3 (x = 5,10,15, …, 30 mol%) and 50B2O3, 30MO, 19ZnO, 1Sm2O3 (M = Ca, Sr and Ba). It is found that the substitution of ZnO for K2O notably enhances the intensity of the red Sm3+emission. Based on the literature this effect is attributed to a change in symmetry at the rare earth position. Additionally, the effect of network modifier concentrations and the different network modifier types on the Sm3+ absorption spectra is examined, discussed and compared to literature data. Furthermore, the glasses are characterized according to their density, refractive index, molar volume, and oxygen packing density.

Analysis of gas-cooled micro modular reactor (MMR) fuel

The gas-cooled micro modular reactor (MMR) is a novel concept with a compact fuel form consisting of thousands of tri-isotropic fuel (TRISO) particles dispersed in a silicon carbide matrix. The MMR fuel has a high volume packing fraction and is horizontally placed within graphite channels. This study demonstrates that the horizontal arrangement of MMR fuel within graphite channels resulted in a non-uniform gap between the fuel and graphite brick, leading to an "off-center" temperature distribution within the fuel, and resulting in differences in TRISO performance even within sub-zones positioned symmetrically in the radial direction. Given the complexity of the fuel structure and the challenges involved in simulation, a multi-scale and multi-physics coupled analysis method of MMR fuel was realized in this work by implementing physical models into the open-source finite element platform MOOSE. Thermal-mechanical analysis and failure analysis within sub-zones of the typical design MMR fuel during normal operation were conducted through simulation. The results indicate that higher-temperature sub-zones exhibit increased internal pressure within TRISO and show greater tensile stress in the Chemical Vapor Deposited Silicon Carbide (CVD-SiC) layer. Regarding fuel failure analysis, this work found limited impact from Pd penetration and kernel migration. Pressure-induced particle failure, closely associated with stress in CVD-SiC, emerges as the primary failure criterion. The probability of fuel failure is relatively low, and interfacial cohesive parameters have an impact on the SiC stress and the fuel failure probability at the highest level.

Experimental and numerical assessment on Pb-free alkaline mixed borate glasses for radiation resisting applications

Melt quenching technique has been used to fabricate calcium boro-phosphate glasses doped with praseodymium oxide ions. With increased P2O5 content, structural parameters like oxygen molar volume (Vo) and oxygen packing density (OPD) indicate an opposing trend. In addition to optical factors like optical electronegativity, absorption edge, and direct and indirect bandgap values being estimated and discussed, optical absorption spectra have been recorded for all the glasses. The presence of ionic bond behaviour confirms the strong structural and optical property changes caused by the P2O5 content. Using the Phy-X software application, the radiation shielding parameters were investigated. The incorporation of B2O3, CaCO3, and P2O5 offers more number of bridging oxygens which further leads to closely packed nature. Considering the glass sample B0PCM:Pr, the highest linear attenuation coefficient (LAC) is determined. The LAC results showed that at high energy levels, the glass's shielding performance became more consistent. The results of the effective atomic number analysis demonstrated the impact that CaCO3 has on the glass's shielding effectiveness, with a higher concentration of CaCO3 improving the material's defence against gamma radiation. For B0PCM:Pr glass, the half value layer (HVL) rises from 2.101 to 3.444 cm at 0.284–1.333 MeV. Certainly, it has been observed that the glass tends to have a smaller HVL when it contains more CaCO3 with lesser P2O5 content.

Shear flow of non-Brownian rod-sphere mixtures near jamming.

We use the discrete element method, taking particle contact and hydrodynamic lubrication into account, to unveil the shear rheology of suspensions of frictionless non-Brownian rods in the dense packing fraction regime. We find that, analogously to the random close packing volume fraction, the shear-driven jamming point of this system varies in a nonmonotonic fashion as a function of the rod aspect ratio. The latter strongly influences how the addition of rodlike particles affects the rheological response of a suspension of frictionless non-Brownian spheres to an external shear flow. At fixed values of the total (rods plus spheres) packing fraction, the viscosity of the suspension is reduced by the addition of "short"(≤2) rods but is instead increased by the addition of "long"(≥2) rods. A mechanistic interpretation is provided in terms of packing and excluded-volume arguments.

Lessons Learned from NASA’s DART Impact about Disrupting Rubble-pile Asteroids

We present a series of numerical simulations using a shock physics smoothed particle hydrodynamics code, investigating energetic impacts on small celestial bodies characterized by diverse internal structures, ranging from weak and homogeneous compositions to rubble-pile structures with varying boulder volume packing. Our findings reveal that the internal structure of these rubble-pile bodies significantly influences the impact outcomes. Specifically, we observe that the same impact energy can either catastrophically disrupt a target with a low boulder packing (≲30 vol%), or result in the ejection of only a small fraction of material from a target with the same mass but high boulder packing (≳40 vol%). This finding highlights the pivotal role played by the rubble-pile structure, effectively acting as a bulk shear strength, which governs the size and behavior of the resulting impact. Consequently, understanding and characterizing the internal structure of asteroids will be of paramount importance for any future efforts to deflect or disrupt an asteroid on a collision course with Earth.

Elucidating the impact of Dy2O3 substitution on structure, optical, photoluminescence and mechanical properties of borosilicate glass

This work aims to investigate the changes in characteristics seen in the composition 60B2O3+ (30–x) BaO + 10SiO2 + xDy2O3 where x is 0.0, 1.0, 2.0, and 3.0 mole% glass samples. Melt-quenching technique was used to prepare the glass samples. A variety of analytical techniques were employed to characterize the prepared glasses, such as x-ray, Raman, photoluminescence, and UV-vis-NIR spectroscopy. XRD spectra verified the glassy nature. The glasses’ compactness was studied using structural properties such as density, molar volume, and oxygen packing density. Makishima-Mackenzie’s (M-M) method was used to determine mechanical parameters such as elastic moduli, Poisson’s ratio, and hardness, and it was found that these properties decreased with increasing Dy2O3 concentration. Glass absorption spectra showed eleven distinct peaks in the range 300–2000 nm, resulting from Dy3+ electronic transitions. Urbach energy, refractive index, and optical band gap energy were determined. The optical parameters, such as molar refraction, molar polarizability, reflection loss, optical transmission, metallization, and optical electronegativity, were estimated. The photoluminescence spectra revealed five distinct peaks in the 400–800 nm wavelength range under excitation at 325 nm.

CALCULATION OF SPECIFIC SURFACE AREA AND POROSITY OF PACKING OF MASS-EXCHANGE COLUMN WITH MODIFIED RASHIG RINGS

New modified Rashig rings are proposed for mass transfer packing columns. Inside these rings, plate elements are attached to rods or springs in the form of rolled spirals with spiral gaps to increase the contact surface area of the phases. A formula linking the porosity and specific surface area of the packing through its geometric dimensions is obtained, allowing for the theoretical determination of one of these parameters based on the known value of the other. An example calculation of specific surface area using the derived formula for a standard Rashig ring is provided. It is demonstrated that the calculation results coincide with reference tabular values. The use of the derived formula in technological calculations of mass transfer columns allows for the theoretical determination of initial parameters (porosity or specific surface area of the packing) without the need for reference or experimental data. An analytical formula for determining the specific surface area of the proposed modified packing is derived. The ordered arrangement of this packing on the support grids of the mass transfer column apparatus is considered, with the spiral element of the modified packing having three turns with uniform spiral gap and made of thin plates. An example calculation of the specific surface area of the proposed modified Rashig ring is given for the considered packing arrangement in the column apparatus. The porosity of the modified packing is calculated using the proposed formula. A comparative analysis of the porosity and specific surface area of the proposed modified Rashig ring with a plate rolled in a spiral inside it and the standard Rashig ring is performed. The results show an increase in specific surface area of the packing in the modified ring by 1.5 times or more, from 65 to 102.7 m2/m3, with a slight decrease in porosity from 0.6 to 0.55 m3/m3. This reduces the calculated height of the packing layer in the mass transfer column apparatus and, consequently, the height and volume of the apparatus itself. The use of the new modified Rashig rings allows for a significant reduction in the total volume of packing in packing columns during extraction, absorption, desorption, and rectification processes.

Design and simulation of rotating packed beds for an industrial acid gas enrichment process

Conventional packed beds are traditionally used for acid gas enrichment processes. Rotating packed beds (RPBs) are unique, compact and effective technology, which can easily replace conventional packed beds for process intensification purposes. Two scenarios are used to substitute Khangiran natural gas refinery enrichment column with a couple of specially designed RPBs. The first scheme mirrors the exact existing process, while the second scenario provides an additional rich solvent stream directly delivered to amine regeneration unit. Aspen Custom Modeler software is employed to perform the entire simulations. As expected, replacing conventional packed bed with RPBs can drastically reduce the geometries of the packed beds and leads to considerable decrease in lean amine consumption. The second scenario performs more adequately and reduces the lean methyl-diethanolamine (MDEA) flow rate entering the enrichment section from 6069 kmole/hr to 5100 kmole/hr. The required enrichment equipment volume is also reduced from 235 m3 to 7.7 m3 (<3% of original value) and the packing volume collapses about 78 folds (from 59 m3 to 0.75 m3). A thorough discussion is also provided on sensitivity analysis of the entire enrichment process versus various input variables (i.e.: RPBs rotational speeds, their operating pressures and the lean amine rate entering enrichment tower). Finally, the results of cost estimation revealed that using the second more optimal RPB scenario reduced both operating costs and captital investments by 15.4% and 85.4%, respectively.

Relating early-age hydration and flow loss of mortar prepared with manufactured sand

Cement-based materials prepared with manufactured sand can exhibit quick loss of fluidity. However, the estimation of the flow loss remains difficult given the variable contents and physiochemical properties of the microfines in various sands. This paper studies the fluidity loss of mortar mixtures made with different manufactured sands varying in mineral composition and content of microfines. The effect of microfines on accelerating the early-age hydration of cement before the deceleration period was evaluated by quantifying the generation of early hydration products. Test results show that the growth of yield stress corresponding to the loss of mini-slump flow of mortar mixtures were mainly determined by the formation of early hydration products, in addition to the volume fraction and packing density of aggregate grains and powder particles. An approach was then proposed that can assess the loss of mini-slump flow of mortar mixtures prepared with manufactured sand, regardless of the type and content of the microfine materials in the sand.