Foam Packing Research Articles

Pressure drop analysis for potential heat transfer applications using metallic foam packing in rotating packed bed

Pressure drop analysis for potential heat transfer applications using metallic foam packing in rotating packed bed

Intensified CO2 Capture in Structured Microreactors with Carbonic Anhydrase Enzyme Immobilized on Open-Cell Foam Packings

Intensified CO₂ Capture in Structured Microreactors with Carbonic Anhydrase Enzyme Immobilized on Open-Cell Foam Packings

Frontal sinus reconstruction with overlapping sinus mucosa and vascularized pericranial flap Coverage after modified transbasal bifrontal craniotomy: Novel technique and clinical outcomes

BackgroundThe modified transbasal bifrontal craniotomy is a variant of the bifrontal craniotomy with a wider surgical corridor than the standard approach. There are several methods for frontal sinus repair in bifrontal craniotomy. This study reports a novel method for frontal sinus repair in the modified transbasal interhemispheric approach by precisely overlapping the frontal sinus mucosa margin (without frontal sinus mucosa exenteration) with packing the frontal sinus with povidone-soaked gel foam and covering it with a vascularized pericranial flap. MethodsIn this case series, we retrospectively collected the clinical outcomes regarding cerebrospinal fluid (CSF) leakage, meningitis, and mucocele formation of patients who underwent modified transbasal bifrontal craniotomy at Vara Hospital. ResultsFrom January 2016 to December 2021, 65 patients with anterior skull-base lesions were treated with a modified transbasal interhemispheric approach with frontal sinus repair by overlapping frontal sinus mucosa with gel foam packing and vascularized pericranium flap covering. There was no case of postoperative CSF leakage, meningitis, or mucocele formation during the follow-up period of 19.2 months (min 1, max 73). ConclusionsWe demonstrated that the modified transbasal interhemispheric approach with frontal sinus repair using gel foam packing and pericranial flap is effective in preventing postoperative CSF leakage and meningitis.

A method of predicting the two-phase liquid-liquid flow resistance in a horizontal pipe with a layer of metal foam

The study reported here is experimental. Its aim was to determine the method applicable for prediction of pressure losses of an unstable two-phase liquid-liquid system flow through a horizontal pipe with a short section of the pipe containing a metal foam packing. However, the flow disturbance resulting from the presence of foam does not lead to a change in the type of the mixture (as there is no phase inversion) nor a permanent emulsification of the flow system. The calculation procedure developed in the study takes into account both the peculiarities that accompany the flow of a two-phase liquid-liquid system in an empty pipe (i.e. type of continuous phase, phase slip, hold-up), as well as geometric parameters of the foam skeleton (i.e. cell and pore dimensions, surface roughness of fibers). The results of experimental research were applied for the purposes of determining the specific form of the equations, consistent with the mathematical model adopted and described in detail in this paper. They were conducted for two foams: aluminum and nickel, which were characterized by the same degree of pore packing (PPI20). The mean dimensions of the elements forming metal foams skeletons were determined by computed tomography. The horizontal flow tube had a diameter of 10 mm and the foam packing occupied it only over a a section with a certain length. In the liquid-liquid system pumped to the pipe, the hydrophilic phase was tap water, while the hydrophobic phase was typical machine oil. The adopted range of flux changes of both liquids corresponded to the conditions at which unstable two-phase systems of the W/O, O/W and W+O type were formed in the empty pipe. The pressure loss of the flowing substance was measured in the foam layer. The values of constants and exponents of the adopted model equation were determined separately for single-phase flow and two-phase systems of various types. The results of the statistical evaluation of the performance of the developed dependencies justify their application in the design procedures of selected heat or mass transfer devices. The equations are dimensionless, and therefore, under the conditions of validity, they should also be effective for other liquid-liquid systems, other foams and flow in a pipe with a different diameter. The developed method is based on a new approach to the description of the two-phase flow resistance through the porous material filling the pipe. In addition, it concerns the flow of a liquid-liquid system, which still forms the area that has been tackled in few publications.

Effect of expanded polyethylene (EPE) foam packing net design on the mechanical damage resistance of strawberry fruit during transportation

Fresh strawberries are susceptible to mechanical damage during transportation, leading to high loss rates. This problem can be addressed through the development of appropriate packaging designs. The initial collision velocity of the fruit and the external packaging would also influence the mechanical damage resistance of the expanded polyethylene (EPE) foam packing net. The dynamic finite element method (FEM) was used to investigate the effect of EPE foam packing net on resisting mechanical damage to strawberry fruits. The results showed that the elastic modulus and diameter of the EPE foam packing net material, as well as the hole size of the net, were key factors affecting the maximum impact force and contact time of the collision process. The initial collision velocity of the fruit and the external packaging also influenced the mechanical damage resistance of the EPE foam packing net. Our results showed that the EPE foam packing net material should have a slightly smaller elastic modulus than that of the strawberry cortex tissue, and the hole size of the net should not be too large. Moreover, when the initial collision velocity and environmental temperature increased by 1 m·s−1 and 1 ℃, the collision damage volume of the fruit increased by 37.6433, and 6.4658 mm3, respectively. This study presents a numerical simulation method that evaluates the collision damage resistance of packed fresh fruit. The findings of this study can serve as a valuable guide for designing packaging solutions and optimizing transportation environments for the long-distance transport of fresh fruit.

Reactive absorption of carbon dioxide in aqueous n-methyldiethanoloamine solutions catalysed with carbonic anhydrase in a rotating packed bed (RPB)

Studies on absorption of carbon dioxide in the rotating packed bed (RPB) were performed with two different types of metal foam packing, and two types of liquid absorbents: 30 wt.% solutions of N-methyldiethanolamine in water, with and without the addition of 0.2 wt.% of carbonic anhydrase. Different rotation speeds, gas flow rates and liquid flow rates were investigated. Results were evaluated using normalized interphase molar flow. Increased rotation speeds and phase flow rates positively affected the interphase mole flow of CO2, but high gas and liquid flow rates limited the operating window due to flooding. The addition of anhydrase significantly increased the absorption efficiency, but also narrowed the operating window. The addition of carbonic anhydrase resulted in an increase in the degree of absorption 2–5-fold for the analogous gas and liquid flow rates, compared to the amine without the biocatalyst. The highest normalized mole flow of 66.3 kmol h−1m−3 was observed for NC1116 packing with the solvent containing anhydrase, while the highest normalized mole flow for solvent without catalyst was 26.2 kmol h−1m−3. The results were compared with analogous absorption processes in a packed column and showed up to 50-fold higher mass transfer efficiency.

Study on the dynamic behaviors of ceramic foam packing humidifier in a micro humid air turbine cycle

• A dynamic model of the humidifier with ceramic foam packing is established. • The model is validated by experimental data at the steady and dynamic state. • The thermal inertia of packing plays a significant role in the transient process. • The dynamic response characteristics of the outlet parameters are analyzed. Mastering the dynamic characteristics is necessary to establish a new control system for the Humid Air Turbine (HAT) cycle. In this research, a one-dimensional dynamic model of the humidifier with ceramic foam packing is established and validated at the steady and dynamic state by the experimental data. The thermal inertia of packing plays a significant role in the transient process. The dynamic response characteristics of outlet parameters are analyzed under the assumed disturbance of inlet water temperature and water flow. It is shown that the simulation results are in good agreement with the experimental data with a maximal relative error of 2.63%. The outlet air temperature is more sensitive to the disturbance of inlet water temperature. The response time of outlet water temperature is about twice longer than that of outlet air temperature under the step disturbance of inlet water flow or temperature. When the inlet water temperature increases, the response time of outlet parameters can be reduced by decreasing its flow. The dynamic characteristics of the humidifier provided in this paper can provide a reference for the development of the control system of the HAT cycle.

Experimental and Prenemilary Numerical Evaluation of Pressure Drops under the Conditions of the Stratified Gas-Liquid Flow in a Horizontal Pipe Filled with Metal Foam

The paper reports the results of experimental tests and numerical simulations related to the pressure drop during two-phase air-water mixture flow through a pipe containing metal foam packing. Aluminium foam with 40 PPI open cells was used in the tests. A horizontal pipe with an internal diameter of 10 mm was used, and the foam only occupied a section of the pipe length equal to 240 mm. In the section of the pipe upwards of the foam, stratified flow pattern was generated, i.e., the most characteristic type for the gas-liquid flow. The results of the experimental research were compared with the values derived on the basis of the empirical method, which was developed for several different metal foams and two-phase systems. The values derived from measurements and calculations were subsequently applied to validate one numerical simulation method that is known to be particularly applicable for two-phase gas-liquid flow through metal foams. As a final result, the phenomena resulting from the presence of foam in the stratified flow through a gas-liquid system, the deficiencies of the methods applied in calculating pressure drops and modeling their values in accordance with the adopted numerical procedure were indicated. All research and modelling were carried out with the purpose of testing the potential of metal foam use in pipes dedicated to heat exchanger design, particularly ones intended to improve energy efficiency.

Calculation method for heat and mass transfer apparatuses with porous plastic contact devices

The development of effective contact devices for heat and mass transfer apparatuses, which allow increasing the intensity of heat and mass transfer processes, reducing the size and cost of technological equipment, is an important practical task of the modern food industry. In this regard, the high efficiency of foam contact devices is noted, due to the developed specific surface and low hydraulic resistance. In the course of the study, a general classification of these devices has been proposed; schematic diagrams of the constructions of foam packings and trays have been given, a brief comparative analysis of their application area has been carried out. The main stages of calculation of highly efficient heat and mass transfer apparatuses with cellular plastic contact devices, including the determination of the basic geometrical characteristics of cellular materials, packing height (plate thickness), number of packing sections (number of plates), hydraulic resistance of packed and plate apparatus, have been described in detail. An example of an engineering calculation of a distillation heat and mass transfer apparatus with packed and plate-shaped foam contact devices for the separation of a binary mixture "ethyl alcohol - water" has been considered. The results of the calculation are presented in tabular and graphical form and allow us to conclude that it is most expedient to use packed foam contact devices with smaller dimensions and hydraulic resistance.

Hydrodynamics and liquid–solid mass transfer in micropacked bed reactors with copper foam packing

Hydrodynamics and liquid–solid mass transfer in micropacked bed reactors (μPBRs) with copper foam packing are investigated. Effects of fluid superficial velocities, liquid viscosity, pore diameter of foam packing on the residence time distribution, liquid holdup, axial dispersion coefficient, and liquid–solid mass transfer coefficient are discussed. The liquid holdup of μPBRs can reach 0.23 ∼ 0.39, which is larger than that of packed bed reactors (0.05). The axial dispersion coefficient of μPBRs is 3.17 × 10-6 ∼ 2.30 × 10-5 m2/s, which is similar with that of packed bed reactors. The value of liquid–solid volumetric mass transfer coefficient with effect of axial dispersion coefficient in μPBRs can reach 0.033 ∼ 0.13 s−1, which is higher than that of packed bed reactors (0.006 ∼ 0.09 s−1). The empirical models of liquid holdup, axial dispersion coefficient, and liquid–solid mass transfer coefficient in single liquid phase flow and gas–liquid two phase flow of μPBRs are established and their predictions are in good agreement with experimental values.

Analysis of polishing waste ceramic foam packing in evaporative cooling

This paper proposes the use of ceramic polishing slag to make fillers for evaporative coolers. The experimental tests on the heat transfer performance of the ceramic foam packing are carried out by using the independent test bench, focusing on the effects of the packing's flow channel form, drench density, the inlet air volume and pressure drop on the heat, and the mass transfer performance of the packing. The experimental results show that the optimum drench density of the ceramic foam packing in the form of a folded runner and a linear runner is 10.0 and 6.7 kg/(m·h), respectively. The direct evaporative cooling efficiency of the ceramic foam packing in both runners tends to decrease with the decrease in the dry and wet bulb temperature difference of the inlet air and the increase of the air mass flow rate. Under the same experimental conditions, the direct evaporative cooling efficiency, optimum inlet air velocity, and pressure drop of the packing in the form of a folded flow channel are higher than those of the linear flow channel. The optimal inlet air velocities of the packing in the form of a folded runner under the conditions of Urumqi, Xi'an, and Guangzhou are 1.6, 1.4, and 1.0 m/s, respectively, and the direct evaporative cooling efficiency can reach 83.01%, 70.74%, and 66.41%. In comparison, the optimal inlet air velocity for all three conditions under the linear runner is 1.0 m/s, and the direct evaporative cooling efficiencies are 73.78%, 68.56%, and 63.28%, respectively.

Modeling of three‐phase continuously operating open‐cell foam catalyst packings: Sugar hydrogenation to sugar alcohols

AbstractAn advanced comprehensive and transient multiphase model for a trickle bed reactor with solid foam packings was developed. A new simulation model for isothermal three‐phase (gas–liquid–solid) catalytic tubular reactor models was presented where axial, radial, and catalyst layer effects were included. The unique feature of this model is that the material balances include most of the individual terms (i.e., internal diffusion, gas–liquid, and liquid solid mass transfer, kinetics) for solid foam packing which is seldom done. Hydrogenation of arabinose and galactose mixture on a ruthenium catalyst supported by carbon‐coated aluminum foams was applied as a fundamentally and industrially relevant case study. Parameter estimations allowed to obtain reliable and significant parameters. The effect of the kinetic parameters and the operation conditions on the arabinose and galactose conversions was studied in detail by sensitivity analysis. The model described is applicable for other three‐phase continuous catalytic reactors with solid foam packings.

Location optimization of silicon carbide foam packings in the unstirred packing trays reactor for the enhancement of solidified natural gas storage

Solidified natural gas technology shows significant potential for storing safely multi-fold volumes of natural gas in clathrate hydrates, but the main concern is the stochastic and slow process of hydrate nucleation making it unstable and unpredictable in practice. To overcome this limitation, methane hydrate was synthesized in a silicon carbide (SiC) ceramic foam packing trays reactor without stirring. Results suggested that the packing trays should be located near the gas-water interface instead of immersed in the aqueous phase, which decreased the induction time by about 98%. Results also highlighted the synergistic effects between the capillary wicking from the porous packings and the water suction from the initially formed hydrate clusters, which pumped water from the aqueous phase into the packings’ pores to provide an unsaturated porous environment for hydrate nucleation. It demonstrated that these two driving forces might also compete for water which became adverse to hydrate formation.

Collagen sponge is as effective as autologous fat for grade 1 intraoperative cerebral spinal fluid leakage repair during transsphenoidal surgery

ObjectiveTo compare the efficacy of collagen sponge graft versus autologous fat graft in repairing grade 1 intraoperative CSF leakage and identify potential risk factors for failure repairing. MethodsWe retrospectively recruited patients with grade 1 intraoperative CSF leakage repaired either with a collagen sponge (Group A), with autologous fat graft (Group B), or with only bipolar coagulation and gel foam packing (Group C). Patients with previous radiotherapy, repaired with additional materials, received postoperative lumbar drainage or without sufficient follow-up data were excluded. The primary outcome was the incidence of postoperative CSF leakage. We used propensity score matching to adjust for confounding when comparing Group A and Group B. Results459 patients (277 female and 182 male) were recruited. Among them, 296 patients were in Group A, 146 patients were in Group B, and the other 17 patients were in Group C. After propensity score matching, 146 and 146 patients were included in group A and group B, respectively. No difference was observed for the primary outcome in the matched cohort (p = 0.654) with three patients in Group A (1.0% and 2.1% before and after matching, respectively) and two patients in Group B (1.4% and 1.4% before and after matching, respectively) developed postoperative CSF leakage, respectively. Patients repaired only with gel foam and/or bipolar coagulation (OR 770.5, p < 0.001) and older age (OR 1.16, p < 0.001) were associated with a higher likelihood of postoperative CSF leakage. ConclusionsCollagen sponge is as effective as an autologous fat graft for grade 1 intraoperative CSF leakage repair during transsphenoidal surgery. Repair with gel foam and/or bipolar coagulation and older age are associated with a higher likelihood of postoperative CSF leakage.

Controllable and high-throughput preparation of microdroplet using an ultra-high speed rotating packed bed

Microdroplets and their dispersion, with a large specific surface area and a short diffusion distance, have been applied in various unit operations and reaction processes. However, it is still a challenge to control the size and size distribution of microdroplets, especially for high-throughput generation. In this work, a novel ultra-high speed rotating packed bed (UHS-RPB) was invented, in which rotating foam packing with a speed of 4000–12000 r·min−1 provides microfluidic channels to disperse liquid into microdroplets with high throughput. Then generated microdroplets can be directly dispersed into a continuous falling film for obtaining a mixture of microdroplet dispersion. In this UHS-RPB, the effects of rotational speed, liquid initial velocity, liquid viscosity, liquid surface tension and packing pore size on the average size (d32) and size distribution of microdroplets were systematically investigated. Results showed that the UHS-RPB could produce microdroplets with a d32 of 25–63 μm at a liquid flow rate of 1025 L·h−1, and the size distribution of the microdroplets accords well with Rosin–Rammler distribution model. In addition, a correlation was established for the prediction of d32, and the predicted d32 was in good agreement with the experimental data with a deviation within ± 15%. These results demonstrated that UHS-RPB could be a promising candidate for controllable preparation of uniform microdroplets.

Modeling the Impact of Active Material Volume Change on Accessible Capacity in Automotive Pouch Cells

Lithium-silicon chemistries show promise to increase battery capacity; however, silicon expands significantly during lithium intercalation, leading to inaccessible capacities as well as cell or pack failure due to pressure generation. Silicon-graphite (Si/C) composite anodes are used to increase the anode capacity while maintaining a tolerable degree of active material volume expansion. Recently, Dash and Pannala modeled anodes with increasing Si/C ratios and explored the tradeoff between increasing gravimetric capacity and the increasing active material volume expansion upon Li intercalation [1]. Their conclusion highlights that while the gravimetric capacity increases, there is ultimately a “threshold value” where the volumetric capacity will begin to decrease to account for the significant silicon volume expansion.This concept was built upon to account for electrochemical and mechanical design limitations applicable to battery packs for electric vehicles (EVs). We propose that increasing the Si/C ratio does not directly lead to an increase in the accessible capacity, because excessive volume expansion can lead to unacceptable cell pressure or electrode porosity. In order to predict the accessible capacity as a function of Si/C ratio, we integrated mechanical behavior for each individual cell component (e.g., composite anode, cathode, and foam packing) into our previous battery model [2-4]. This model can predict the split between changes in electrode porosity and dimensions by coupling component mechanical behavior to the volume change governed by electrochemical phenomena.In this presentation, we will focus on how the Si/C ratio will impact both mechanical and electrochemical behavior using our mechano-electrochemical model. Figure 1 shows an example of the pressure generation seen when considering (a) foam packaging and (b) a rigid volume for cells with varying percentages of Si in the anode. Accessible capacities of these materials can then be determined for a specific design’s pressure cutoff. Preliminary modeling of the links between active material Eeq, anode/cathode capacity balance, and volume change will also be discussed.

Evaluation of performance improvements through application of anisotropic foam packings in rotating packed beds

Constantly increasing interest in HIGEE technology and rotating packed beds require detailed investigations of the mass transfer and hydrodynamic performance. Classical isotropic single block packings constitute the most applied and investigated packings for absorption and stripping processes. Yet, the large geometric surface area which is offered by these packings can hardly be exploited to the full extent due to the constant change in gas and liquid loads along the radius of the annular packings. In order to overcome these limitations and extend the operating range and mass transfer performance of foam packings, the current study presents a detailed comparison of isotropic and anisotropic packings. The conducted pressure drop and mass transfer experiments, based on chemical absorption of CO2 with aqueous sodium hydroxide, illustrate the improved performance that can be expected from anisotropic packings, while dedicated gamma-ray computed tomography provides further insight into the improved liquid distribution for this kind of packings.

Liquid-solid mass transfer in a rotating packed bed reactor with structured foam packing

A rotating packed bed (RPB) reactor has substantially potential for the process intensification of heterogeneous catalytic reactions. However, the scarce knowledge of the liquid–solid mass transfer in the RPB reactor is a barrier for its design and scale-up. In this work, the liquid–solid mass transfer in a RPB reactor installed with structured foam packing was experimentally studied using copper dissolution by potassium dichromate. Effects of rotational speed, liquid and gas volumetric flow rate on the liquid–solid mass transfer coefficient (kLS) have been investigated. The correlation for predicting kLS was proposed, and the deviation between the experimental and predicted values was within ± 12%. The liquid–solid volumetric mass transfer coefficient (kLSaLS) ranged from 0.04–0.14 1−1, which was approximately 5 times larger than that in the packed bed reactor. This work lays the foundation for modeling of the RPB reactor packed with structured foam packing for heterogeneous catalytic reaction.

Assessment of the Resilience against Liquid Maldistribution of Monolith Packings under Offshore Floating Conditions

The study provides insights for adapting commercially available packings to work on floating vessels in the marine context aiming at preserving performances similar to land-based packed-bed reactors. Specifically, liquid distribution for cocurrent gas-liquid downflow (Ug = 0.0065-0.131 m/s and Ul = 0.001-0.0078 m/s) inside monolith packings embarked on a hexapod emulator was compared against glass-bead containing trickle bed and open-cell foam packings using wire-mesh sensors under vertical, inclined and rolling column conditions. Sensitivity of the tested internals with regard to liquid maldistribution was diagnosed and analyzed in terms of a maldistribution factor for the vertical/inclined and rolling columns. Liquid maldistribution was found to prevail at high gas and low liquid superficial velocities for the tested three packings regardless of column conditions. Monolith packed beds demonstrated superior robustness to counteract liquid maldistribution induced by bed static inclinations and roll motion...

Time-resolved characterization of non-thermal plasma-assisted photocatalytic removal of nitric oxide

We performed time-resolved characterization of plasma-photocatalytic removal of nitric oxide (NO) in a ceramic foam packing double dielectric barrier discharge reactor using mid-infrared laser absorption spectroscopy. Non-thermal plasma (NTP) was generated in the porous ceramic foam coated with mesoporous TiO2 thin film. Real-time NO monitoring was performed using a quantum cascade laser at 5.26 µm combined with a custom-designed multipass gas cell, leading to a sub-ppm detection limit at 0.1 s measurement time. By analyzing the feed gas of 90 ppm NO/1% O2 balanced in N2, the plasma treatment without TiO2 photocatalyst had no effect on NO removal when the discharge power was below 45 W. In comparison, the NTP-TiO2 system achieved an efficiency of 49% for NO removal even at the relatively low discharge power of 18 W. The synergy between NTP and TiO2 photocatalyst effectively promotes the NO removal at low plasma discharge powers. However, we also observed a negative effect of TiO2 photocatalyst on NO removal at a relatively high discharge power of 135 W.