scholarly journals Effects of Particle Combinations With Different Wettability on Foam Structure and Stability

2021 ◽  
Vol 8 ◽  
Author(s):  
Dianqiao Geng ◽  
Jiahui Li ◽  
Huaying Li ◽  
Wenzhan Huang
Keyword(s):  
Metal Foam ◽  
Foam Stability ◽  
Water Solution ◽  
Wetting Angle ◽  
Single Type ◽  
Gas Migration ◽  
Foam Structure ◽  
Foam Metal ◽  
Viscosity Enhancement ◽  
Better Than

Particle addition is an important method to prepare foam metal, and it is of great significance to clarify the mechanism of particle stabilizing liquid metal foam. In this paper, ethanol-water solution system is used to simulate liquid melt foam. By changing the wettability of particles to adjust the distribution position of particles in foam, two types of particles with different wettability are added, which are mixed and optimized in a certain proportion to improve the foam stability as much as possible. The main mechanism is that the large wetting angle particles at the gas-liquid interface to slow down the gas migration, while small wetting angle particles exist in the liquid film, which can reduce the liquid drainage velocity. The experimental results show that the effect of particle wettability on foam structure is greater than that on viscosity enhancement. The particles with large wetting angle are beneficial to the formation and stability of foam, and the particles with small wetting angle cannot stabilize the foam alone. The effect of two types of particle combinations with different wettability on foam stability is better than that of single type of particle. Considering the height and uniformity of the foam structure, the optimal particle combination is finally obtained.

Effect of fin-metal foam structure on thermal energy storage: an experimental study

2021 ◽  
Author(s):  
Junfei Guo ◽  
Zhan Liu ◽  
Zhao Du ◽  
Jiabang Yu ◽  
Xiaohu Yang ◽  
...  
Keyword(s):  
Experimental Study ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Metal Foam ◽  
Foam Structure

Numerical Study of Heat Conduction of High Porosity Open-Cell Metal Foam/Paraffin Composite at Pore Scale

2016 ◽  
Author(s):  
Yuanpeng Yao ◽  
Huiying Wu ◽  
Zhenyu Liu
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Pore Size ◽  
Metal Foam ◽  
Foam Cell ◽  
High Porosity ◽  
Pore Scale ◽  
Thermal Equilibrium State ◽  
Foam Structure ◽  
Open Cell

In this paper, a numerical model employing 3D foam structure represented by Weaire-Phelan foam cell is developed to study the steady heat conduction of high porosity open-cell metal foam/paraffin composite at the pore-scale level. Two conduction problems are considered in the cubic representative computation unit of the composite material: one with constant temperature difference between opposite sides of the cubic unit (that can be used to determine the effective thermal conductivity (ETC)) and the second with constant heat flux at the interface between metal foam and paraffin (that can be used to determine the interstitial conduction heat transfer coefficient (ICHTC)). The effects of foam pore structure parameters (pore size and porosity) on heat conduction are investigated for the above two problems. Results show that for the first conduction problem, the effect of foam structure on heat conduction (i.e. the ETC) is related to porosity rather than pore size. The essential reason is due to the thermal equilibrium state between metal foam and paraffin indicated by the negligible interstitial heat transfer. While for the second conduction problem with inherent thermal non-equilibrium effect, it shows that both porosity and pore size significantly influence the interstitial heat conduction (i.e. the ICHTC). Furthermore, the present ETC and ICHTC data are compared to the results in the published literature. It shows that our ETC data agree well with the reported experimental results, and are more accurate than the numerical predications based on body-centered-cubic foam cell in literature. And our ICHTC data are in qualitative agreement with the published numerical results, but the present results are based on a more realistic foam structure.

A Study on the Design and Mechanical Adhesion of Polymer Foam-Metal Joints

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Ahsan Ahmed ◽  
Atef Fahim ◽  
Hani Naguib
Keyword(s):  
Load Transfer ◽  
Metal Foam ◽  
Research Work ◽  
Polymer Foam ◽  
Structural Element ◽  
Foaming Process ◽  
Flexural Testing ◽  
Mechanical Adhesion ◽  
Foam Metal ◽  
And Behavior

The design of metal-polymer foam adhesion and load transfer characteristics is carried out in this research work. The metal inserts are used as the load transfer component, while the foam is used as the structural element of the system. The inserts are embedded in the foam during the foaming process. Flexural testing was conducted on different metal foam configurations to establish the typical interaction trends. The load-deflection response and the mode of failure of the structure were documented. Moduli of elasticity of the system for various geometries and embedded lengths were evaluated, and behavior patterns were gleaned. Rectangular, circular, and triangular (taper-/wedgelike) inserts were used. Results show that simple taper inserts embedded in foam slabs perform better than the other shapes. Finite element analyses of the interaction under different loads were carried out. The modeling results coincided with the experimental ones hence validating the model.

scholarly journals The Modification of Sodium Polyacrylate Water Solution Cooling Properties by AL2O3

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
Wojciech Gęstwa ◽  
Małgorzata Przyłęcka
Keyword(s):  
Heat Transfer ◽  
Impact Strength ◽  
Water Solution ◽  
Wetting Angle ◽  
Sodium Polyacrylate ◽  
Cooling Curves ◽  
Dimensional Changes ◽  
Quenching Media ◽  
Cooling Medium ◽  
Cooling Speed

This paper presents a preliminary examination of water cooling ability as a result of its modification by the addition of sodium polyacrylate and AL2O3nanoparticles. (AL2O3) alumina oxide was present in gamma phase as a form of nanopowder whose particle size was less than 50 nm. Cooling curves in the temperature-time system were marked for the three cooling media: water, 10% water solution of sodium polyacrylate, and 10% water solution of sodium polyacrylate with 1% addition of AL2O3nanoparticles. Based on cooling curves, it can be concluded that for the water solution of sodium polyacrylate with AL2O3nanoparticles in comparison to water and 10% polymer water solution lower cooling speed is obtained. The cooling medium containing nanoparticles provides lower cooling speed in the smallest surface austenite occurance (500–600 C) in the charts of the CTP for most nonalloy structural steels and low-alloy steels. However lower cooling temperature at the beginning of martensitic transformation causes the formation of smaller internal stresses, leading to smaller dimensional changes and hardening deformation. For the quenching media the wetting angle was appointed by the drop-shape method. These studies showed the best wettability of polymer water solution (sodium polyacrylate) with the addition of AL2O3nanoparticles, whose wetting angle was about 65 degrees. Obtaining the smallest wetting angle for the medium containing nanoparticles suggests that the heat transfer to the cooling medium is larger. This allows slower cooling at the same time ensuring its homogeneity. The obtained values of wetting angle confirm the conclusions drawn on the basis of cooling curves and allowus to conclude that in the case of the heat transfer rate it will have a lower value than for water and 10% polymer water solution. In the research on hardened carburized steel samples C10 and 16MnCr5 surface hardness, impact strength and changes in the size of cracks in Navy C-ring sample are examined. On this basis of the obtained results it can be concluded that polymer water solution with nanoparticles allows to obtain a better impact strength at comparable hardness on the surface. Research on the dimensional changes on the basis of the sample of Navy C-ring also shows small dimensional changes for samples carburized and hardened in 10% polymer water solution with the addition of nanoparticles AL2O3. Smaller dimensional changes were obtained for samples of steel 16MnCr5 thanfar C10. The results allowus to conclude that by the addition of solid nanoparticles to water based quenching media their cooling properties which are not inferior to mineral oils and polymer water solutions can be shaped.

scholarly journals Novel Foam Adsorbents in Dyes and Heavy Metals Removal: A Review

2021 ◽  
Vol 33 (3) ◽  
pp. 499-508
Author(s):  
Suresh Selvaraj ◽  
S. Ravichandran ◽  
S.R. Boselin Prabhu ◽  
G.K. Prashanth ◽  
H.M. Sathyananda
Keyword(s):  
Heavy Metals ◽  
Metal Foam ◽  
Carbon Foam ◽  
Polymer Foam ◽  
Heavy Metals Removal ◽  
Future Possibility ◽  
Adsorption Performance ◽  
Metals Removal ◽  
Foam Metal ◽  
Chelating Ability

The present review comprises various novel foam adsorbents with unique adsorption performance in process of removal of dyes and heavy metals. Water pollution because of toxic dyes and heavy metals and its ill-effect on the ecosystem is of great concern to researchers, as it affects the living creatures on the planet. Novel foam adsorbents from carbon foam, chitosan foam, metal foam and polymer foam were developed as efficient materials with good chelating ability to adsorb dyes and heavy metal ions. Novel carbon foam adsorbents were reported to have superior adsorption capacity in removal of dyes and heavy metals. This review aims to look at various novel foam adsorbents used in adsorption studies and their potential in dyes and heavy metals removal. This work provides a worthy challenge and the future possibility for designing novel foam materials for various applications.

scholarly journals Quick-dip and contact method of cutting rooting of Zelkova carpinifolia (Pall.) K. Koch as an alternative non-invasive species

2012 ◽  
pp. 51-60
Author(s):  
Mihailo Grbic ◽  
Dragana Skocajic ◽  
Matilda Djukic ◽  
Danijela Djunisijevic-Bojovic ◽  
Dragica Obratov-Petkovic ◽  
...  
Keyword(s):  
Invasive Species ◽  
Water Solution ◽  
Polyethylene Film ◽  
Contact Method ◽  
Rooted Cuttings ◽  
Non Invasive ◽  
Rooting Of Cuttings ◽  
Low Tunnels ◽  
Secondary Roots ◽  
Better Than

Two methods of rooting of Zelkova softwood cuttings were analyzed: (1) quick-dip method and (2) contact method - the thin polyethylene film (20 mm) laid directly over the cuttings during the rooting process. The control for contact method was a low tunnel with a thick polyethylene film. One group of cuttings in the contact method was treated with quick-dip (IBA 2,500 ?g?mL-1, carrier-ethyl alcohol) during 5 sec, and the other group was treated with water solution of IBA (50 ?g?mL-1) in 24-hour treatment. The third group was control - untreated cuttings. The same groups of cuttings were also used in low tunnels. The number and length of primary and secondary roots were measured on rooted cuttings. The results of all treatments show that contact method in combination with water solution of IBA was the best with 92% of rooted cuttings. No significant differences were obtained between this treatment and quick-dip + contact method (85.3%). Rooting of cuttings under low tunnel was significantly lower. In general, contact method was better than low tunnel, disregarding the carrier used. These results recommend the almost unknown contact method in nursery propagation of Zelkova, as an alternative, non-invasive species for the conditions in Serbia.

The Inhibition Effect of Imidazoline and Diethylene Triamine on the Stress Corrosion Cracking of 08Cr2AlMo Steel in H2S Solution

2007 ◽  
Vol 353-358 ◽  
pp. 2467-2470
Author(s):  
Yao Feng Zhang ◽  
Bo Qin Gu
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Steel Surface ◽  
Electrochemical Impedance ◽  
Water Solution ◽  
Corrosion Cracking ◽  
Inhibition Effect ◽  
Diethylene Triamine ◽  
Scanning Electron ◽  
Better Than

08Cr2AlMo steel is a type of material developed especially for heat exchanger pipe bundle used under H2S condition in the recent years. In this paper, some researches were carried out on the stress corrosion cracking (SCC) susceptivity of 08Cr2AlMo steel in H2S water solution and the inhibition of imidazoline and diethylene triamine on the SCC by means of slow strain rate tensile test, scanning electron microscopy, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results indicate that 08Cr2AlMo steel is highly susceptible to SCC in saturated H2S solution for the fracture surfaces of specimen show typical quasi-cleavage fracture. The addition of both imidazoline and diethylene triamine into saturated H2S solution is effective on inhibiting the SCC. The inhibitors can reduce the potential of the cathodic hydrogen evolution, which prevents the penetration of hydrogen into the specimen effectively. Furthermore, inhibitors accelerate the formation of the chemically bonded film on the steel surface. It is also found that when the concentration of inhibitors is below 0.2%, there is no obvious inhibition effect on SCC, and the inhibition effect of diethylene triamine is better than that of imidazoline.

Study on Foam Properties of Alkylbenzene Sulfonate Gemini Surfactants

2011 ◽  
Vol 418-420 ◽  
pp. 528-531 ◽  
Author(s):  
Xi Gang Du ◽  
Chun Wei Wang ◽  
Rui Qi Niu ◽  
Jun Zhang ◽  
Zhen Yu Yang
Keyword(s):  
Gemini Surfactants ◽  
Foam Stability ◽  
Hydrophobic Group ◽  
Alkylbenzene Sulfonate ◽  
Foam Properties ◽  
The Stability ◽  
Alkyl Length ◽  
Better Than

Foamability and foam stability of alkylbenzene sulfonate Gemini surfactants solution were studied with Ross-Miles method. The variations of foamability and foam stability with concentration, Hydrophobic group and temperature were studied, respectively. It was found that foamability begins to increase with increment of concentration, when concentration increases to a degree, foamability no longer increases. And foamability decreases with increment of alkyl length in the whole concentrations. The stability of surfactants begin to increase with increment of concentration. When concentration is increased to 0.5 g/L, the stability begin to decrease. And the stability of Ic is much better than that of Ia. Furthermore, the foamability of Ia and Ic increases with temperature, however the foam stability of them decreases with temperature.

scholarly journals Practical Lessons on 12-Lead ECG Classification: Meta-Analysis of Methods From PhysioNet/Computing in Cardiology Challenge 2020

2022 ◽  
Vol 12 ◽  
Author(s):  
Shenda Hong ◽  
Wenrui Zhang ◽  
Chenxi Sun ◽  
Yuxi Zhou ◽  
Hongyan Li
Keyword(s):  
Data Augmentation ◽  
Meta Analysis ◽  
Single Type ◽  
Training Strategy ◽  
Advantages And Disadvantages ◽  
The Common ◽  
Classification Tasks ◽  
Electrocardiogram Ecg ◽  
And Training ◽  
Better Than

Cardiovascular diseases (CVDs) are one of the most fatal disease groups worldwide. Electrocardiogram (ECG) is a widely used tool for automatically detecting cardiac abnormalities, thereby helping to control and manage CVDs. To encourage more multidisciplinary researches, PhysioNet/Computing in Cardiology Challenge 2020 (Challenge 2020) provided a public platform involving multi-center databases and automatic evaluations for ECG classification tasks. As a result, 41 teams successfully submitted their solutions and were qualified for rankings. Although Challenge 2020 was a success, there has been no in-depth methodological meta-analysis of these solutions, making it difficult for researchers to benefit from the solutions and results. In this study, we aim to systematically review the 41 solutions in terms of data processing, feature engineering, model architecture, and training strategy. For each perspective, we visualize and statistically analyze the effectiveness of the common techniques, and discuss the methodological advantages and disadvantages. Finally, we summarize five practical lessons based on the aforementioned analysis: (1) Data augmentation should be employed and adapted to specific scenarios; (2) Combining different features can improve performance; (3) A hybrid design of different types of deep neural networks (DNNs) is better than using a single type; (4) The use of end-to-end architectures should depend on the task being solved; (5) Multiple models are better than one. We expect that our meta-analysis will help accelerate the research related to ECG classification based on machine-learning models.

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