Air Foam Research Articles

Study of the Effect of Drive Gas Type on the Inhibition of Coal Spontaneous Combustion by Ternary System Foam

ABSTRACT Evaluation of the fire extinguishing capacity of homemade foams under different driving gases by thermogravimetric experiments. When the concentration of LS-99/SDS/isobutyl alcohol is 0.1%, the expansion ratio can be 52.54 times, 25% drainage time is 210s. Coal spontaneous combustion processes shift toward the high temperature region under the action of foam. The maximum mass loss velocity is reduced. Activation energy analysis shows that the composite inhibition rate of air foam is 64.56%, and nitrogen foam has a 28.18% increase compared to air foam. The heat release decreases under the action of air foam. The coal sample exhibits a heat absorption process in the presence of nitrogen foam. In addition, the mechanism of foam inhibition of coal spontaneous combustion was analyzed from physical and chemical perspectives. In summary, nitrogen foam is more effective than air foam in extinguishing spontaneous coal combustion processes.

Compact, flexible and highly selective wideband complementary FSS with high angular stability

AbstractThis article presents a novel miniaturized (0.105λ0 × 0.105λ0) flexible complementary frequency selective surfaces (CFSS) structure with sharp band edge selectivity and very high angular stability. To explore two diverse applications as a passband and stopband filter, a novel complementary convoluted square loop (CCSL) type structure has been designed and investigated on ultrathin dielectric material of thickness 0.0023λ0. The second-order wide controllable passband with fractional bandwidth of 19.23% (−3 dB) and remarkably wide stopband of 64.7% (−10 dB) and 54.8% (−20 dB) respectively have been achieved by using a cascaded resonating structure which is composed of asymmetrical meandered CCSL array, arranged on two ultrathin dielectric layers with air foam separation. This particular format would lead to sharp band edge selectivity with steep roll-off (72.43 dB/GHz) and an excellent passband selectivity factor (0.731). An equivalent lumped LC circuit in conjunction with the transmission line model has also been adopted to comprehend the physical mechanism of the proposed single layer and double layer structures. Further, better passband and stopband angular stability at an oblique incident angle of 45° and the bending characteristics have also been investigated thoroughly for the proposed flexible CFSS to check their employability in different conformal structures with WiMAX passband and WLAN stopband application.

Effect of reservoir permeability on oil recovery using air foam flooding: a case study on Ganguyi oilfield

Air foam flooding is an important technology to enhance oil recovery by improving the swept volume of the fluid and the efficiency of displacement of oil. This study uses a literature review, engineering analysis of reservoirs, laboratory tests, and the data on oil production to clarify the relationship among the efficiency of oil displacement, control of the profile of the mechanism of water blockage, and the permeability of the reservoir. The results show that a highly permeable reservoir has a good pore structure with a large pore throat that helps yield a large swept volume and low interfacial tension to improve the efficiency of oil displacement. It also contains large pores that generate more foam for a higher oil mobility ratio and greater oil displacement. A heterogeneous reservoir has a strong Jamin effect and efficient oil displacement when air foam flooding is applied. The results of experiments yielded similar conclusions. The displacement efficiency of highly permeable and heterogeneous reservoirs is higher, and their injection pressure is lower when air foam flooding is applied. The permeability of reservoirs in oil fields should be higher than 1.5 mD for injection using air foam flooding. The results here can be used in applications of air foam flooding.

Comparison of Gaseous and Water-Based Medium-Expansion Foam Depopulation Methods in Cull Sows.

Simple SummaryIn the face of a swine health crisis, emerging zoonotic diseases or environmental catastrophe, the mass depopulation of swine may be required to prevent the additional spread of disease and to minimize animal pain or suffering. Due to the increasing risk of global disease outbreaks, the U.S. swine industry needs feasible guidelines in place in preparation for such events. Current American Veterinary Medical Association (AVMA) approved swine depopulation methods can be difficult to implement under field conditions. Emergency depopulation using inhalants such as carbon dioxide (CO2) and nitrogen gas (N2) or the use of aspirated foam agents have been approved and conducted in poultry in the US, but are not approved for use in other livestock. Our findings, using cull sows, demonstrate that although CO2, N2 and aspirated foam combinations successfully killed all the animals, CO2 and aspirated foam did so in the shortest timeframe. In addition, the use of aspirated foam was as effective as CO2 for sow depopulation while having potential operational advantages, such as no use of lethal gases and reduced risk of associated equipment failure.The U.S. swine industry is currently inadequately prepared to counteract the increasing threat of high-consequence diseases. Although approved and preferred depopulation guidelines exist, ventilation shutdown (VSD+) is currently the only method being deployed during a state of emergency to depopulate large swine populations. However, the permitted use of VSD+ during constrained circumstances has been criticized due to raised swine welfare concerns. The objective of this study was to investigate the effectiveness of carbon dioxide gas (CO2), nitrogen gas (N2), compressed air foam (CAF), compressed nitrogen foam (CAF-N2) and aspirated foam (AF) during a 15-min dwell time on adult swine in an emergency depopulation situation. A small-scale trial using 12 sows per depopulation method showed the highest efficiency to induce cessation of movement for AF and CO2 (186.0 ± 48 vs. 202.0 ± 41, s ± SD). The ease of implementation and safety favored AF for further investigation. A large-scale field study using AF to depopulate 134 sows in modified rendering trailers showed a mean fill time of 103.8 s (SD: 5.0 s) and cessation of movement of 128.0 s (SD: 18.6 s) post filling. All sows were confirmed dead post-treatment for both trials. The implementation of AF in modified rendering trailers may allow for a safe and reliable method that allows for the expedient and mobile depopulation of both small and large numbers of sows during an emergency.

Wideband Gain Enhancement of High-Isolation Fabry–Pérot Antenna Array With Tandem Circular Parasitic Patches and Radial Gradient PRS

A high-isolation Fabry–Pérot (FP) antenna array with wide bandwidth and high gain is proposed for <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ku</b> -band vehicle satellite communications. Each antenna element consists of a pair of tandem circular parasitic patches (TCPPs), a radial gradient partially reflective surface (PRS), and a reflector, respectively, separated from the ground plane with a double-dumbbell-shaped slot (DDSS) by air layer and foam dielectric. The slot radiator steers the TCPPs to create multiple resonant frequencies and then the impedance bandwidth is widened. The impedance matching could be improved by adjusting four circular slot diameters of the DDSS. The gain is raised by TCPPs and radial gradient PRS, which function to guide the electromagnetic field and uniformize the aperture near-field, successively. The reflector with several resonator elements is used to reduce the backside radiation. As proof of concept, the FP antenna array prototype with a height of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.613\lambda _{0}$ </tex-math></inline-formula> has been fabricated and measurements confirming simulations are provided. Experimental results show that the impedance bandwidth ranges from 13.48 to 16.95 GHz [22.8% fractional bandwidth (FBW)], and the realized gain is up to 21.59 dBi. A decoupling metallic strip could achieve over 40.8 dB isolation. The proposed antenna element is easily extended for the multiple-input multiple-output (MIMO) and beamforming antennas, further improving the directivity.

The Compressive Strength Of Fly Ash Foamed Concrete With Polypropylene Fiber

Lightweight concrete is widely used for various structural applications because its lighter than normal concrete. Foamed concrete is made to produce low-density concrete by introducing air bubbles or foam into it. In the presence of air bubbles, the density of concrete only reaches 300-1700 kg/m 3 [1]. The addition of fly ash can reduce the pores that cause the entry of acids. In addition, the modulus of elasticity in the polypropylene fiber mixture prevents cracked so it can make foamed concrete more ductile than foamed concrete without fibers and can make concrete stronger. The manufacture of foamed concrete specimens was planned by the SNI Module 3 specifications [4] and was equipped with ASTM [2], [3]. The foaming agent content in foamed concrete was 0.8 % where the polypropylene fiber variations are 0 %, 0.15 %, 0.2 %, and 0.3 % with 25 % fly ash as a cement substitute. The compressive strength test results show that the addition of fibers to foamed concrete increases the compressive strength of concrete where the maximum compressive strength produced by foamed concrete with polypropylene fibers is 0.3% and the lowest compressive strength is produced by foamed concrete without fibers.

Monitoring of early‐stage water uptake by hyperspectral imaging and evaluation of nutritional and technological functionality of germinated faba bean (Vicia faba L.) var. minor and var. major as food ingredients

AbstractFaba bean (Vicia faba L.) is a potential, sustainable protein alternative. Germination behavior of Vicia faba L. var. minor and Vicia faba L. var. major needs further studies in order to enable larger scale bioprocessing. In this study, early‐stage water uptake of two distinct faba bean varieties was assessed by hyperspectral imaging. Nutritional and technological functionality of germinated faba bean ingredients as such and in combination with fermentation were evaluated. Hyperspectral imaging revealed that early‐stage water uptake in faba beans occurred evenly from the different sides of the beans. Germination on petri dishes and in pilot‐scale showed that smaller faba beans moistened and germinated significantly (p &lt; 0.05) faster and retained water better through germination than larger faba beans. Germinated faba flour of minor‐type variety resulted in 72% higher dextran production in Weissella confusa VTT E‐143403 fermentation than respective native faba flour. With both types of faba bean varieties, germination as such, and with minor‐type variety, germination as combined with fermentation decreased notably the content of raffinose family oligosaccharides. These bioprocessing methods also improved functionality of faba bean ingredients by increasing protein separation efficiency in air classification, protein solubility, foaming capacity, and foam stability. Based on this study, minor‐ and major‐type or small‐ and large‐seeded faba bean varieties set different requirements to the germination process. In addition, germination alone or as combined with fermentation was proved to improve the nutritional and technological quality of faba bean material promoting its use in several food applications including also gluten‐free products.

Pore-scale numerical simulation of convection heat transfer in high porosity open-cell metal foam under rotating conditions

High porosity open-cell metal foam can be used in rotating machinery to improve its performances. The interstitial heat transfer coefficient is a key parameter to describe heat transfer in porous media under local thermal non-equilibrium conditions. A pore-scale numerical simulation is performed to obtain the interstitial heat transfer coefficient between air and high porosity open-cell metal foam under rotating conditions in this study. To this end, the convective heat transfer in a radially rotating channel filled with Weaire-Phelan foam cell is investigated numerically. The interstitial heat transfer coefficients are calculated at different Reynolds numbers, Rotation numbers, foam porosities and locations. And the correlation for porous-fluid interstitial heat transfer Nusselt number is established. The results show that the increasing of Reynolds and Rotation number will gradually increase the interstitial heat transfer Nusselt number. The location also has a positive effect on the interstitial heat transfer coefficient. However, the interstitial heat transfer Nusselt number gradually decreases with the increase of porosity. The established correlation can predict the interstitial heat transfer Nusselt number with a deviation within 10% at the studied ranges of the corresponding parameters. It can also be applied to the cases for larger location, larger channel size and larger Rotation number.

A research into the potential application of unmanned aerial vehicles in the fire extinguishing of high-rise buildings and structures

Introduction. Fires in high-rise buildings and structures constitute a grave danger both to the people inside, valuables, and the building structure. More often than not, fires develop on the external surface of construction facilities that are in operation or inside those facilities that are under construction, and they give rise to the problem of using standard fire extinguishing solutions and require the employment of mobile machinery by fast response units of the fire-fighting service who apply fire extinguishing agents from the outside of a building. The purpose of this article is to substantiate the in expediency of, or, on the contrary, the need to make the proposed amendments to Federal Law No. 123-FZ of July 22, 2008 “Technical Regulation of Fire Safety Requirements”.The scope of the problem. The analysis of the effectiveness of various methods of application of fire extinguishing agents used to extinguish outdoor fires in high-rise buildings has shown the insufficiently high efficiency of ground-mounted machinery, which preconditions the need to make an enquiry into the possibility of using aircraft to extinguish high-rise buildings and structures. Given the need to ensure effective fire extinguishing, meet safety and economic feasibility requirements, an autonomous unmanned aerial vehicle (AURA) was selected as the delivery vehicle. Systems using various fire extinguishing agents and methods of their application were used for fire extinguishing purposes, including a pulsed water application system, capsules containing the fire extinguishing composition, high-pressure water mist and compressed air foam. Their applicability at the height of 300 meters has determined their choice.Research results. The testing task was to confirm the possibility of application of fire extinguishing agents to the fire seat in the course of the flight of an unmanned aerial vehicle, to identify the effectiveness of fire extinguishing agents and to assess the stability of extinguishing agents applied to the fire seat. To ensure safety, testing was carried out at the height not exceeding 10 m, and the results confirmed the possibility of using the above substances to extinguish fires.Conclusions. The research has confirmed the possibility of using unmanned aerial vehicles and various methods of fire extinguishing by means of the horizontal application of extinguishing agents inside high-rise buildings and structures, if extinguishing agents are applied from outside of a construction facility.

Flow Pattern and Resistance Characteristics of Gas–Liquid Two-Phase Flow with Foam under Low Gas–Liquid Flow Rate

To reduce the cost of arranging air foam flooding equipment at each wellhead, a method of establishing centralized air foam flooding injection stations is proposed. The flow pattern and resistance characteristics of air foam flooding mixtures in different initial conditions are studied. Experimental results indicate that the probability density function of stratified flow is obtained by comparing stainless steel and transparent pipes. If the gas–liquid ratio is kept constant, then the shape of the probability density function remains unchanged in both stainless steel and transparent tubes. Meanwhile, the flow pattern under the gas–liquid ratio is determined by comparing the image recognition results with the probability density function, and a formula for calculating the resistance and pressure drop of the gas and liquid two-phase flow in the horizontal and upward pipes is established. Compared with the experiments, the error results of the calculation are small. Thus, the proposed equations can be used to predict the flow resistance of real air foam flooding.

Advances in Low-Density Flexible Polyurethane Foams by Optimized Incorporation of High Amount of Recycled Polyol.

An industrially manufactured recycled polyol, obtained by acidolysis process, was for the first time proved to be a possible replacement of the reference fossil-based polyol in a low-density formulation suitable for industrial production of flexible polyurethane foams. The influence of increasing recycled polyol amounts on the properties of the polyurethane foam has been studied, also performing foam emission tests to evaluate the environmental impact. Using 10 pbw recycled polyol in the standard formulation, significant differences of the physical properties were not observed, but increase of the recycled polyol amount to 30 pbw led to a dramatic decrease of the foam air flow and a very tight foam. To overcome this drawback, N,N′-bis[3-(dimethylamino)propyl]urea was selected as tertiary amine catalyst, enabling the preservation of foam properties even at high recycled polyol level (30 pbw). Foam emission data demonstrated that this optimized foam formulation also led to an important reduction of volatile organic compounds. The results open the way for further optimization studies in low-density flexible polyurethane foam formulations, to increase the reutilization of the polyurethane waste and reduce the amount of petroleum-based raw materials.

Beds, overlays and mattresses for treating pressure ulcers.

Beds, overlays and mattresses for treating pressure ulcers.

Alternating pressure (active) air surfaces for preventing pressure ulcers

Alternating pressure (active) air surfaces for preventing pressure ulcers

Reactive air surfaces for preventing pressure ulcers.

Reactive air surfaces for preventing pressure ulcers.

Cooling Design for PEM Fuel-Cell Stacks Employing Air and Metal Foam: Simulation and Experiment

A new study investigating the cooling efficacy of air flow inside open-cell metal foam embedded in aluminum models of fuel-cell stacks is described. A model based on a commercial stack was simulated and tested experimentally. This stack has three proton exchange membrane (PEM) fuel cells, each having an active area of 100 cm2, with a total output power of 500 W. The state-of-the-art cooling of this stack employs water in serpentine flow channels. The new design of the current investigation replaces these channels with metal foam and replaces the actual fuel cells with aluminum plates. The constant heat flux on these plates is equivalent to the maximum heat dissipation of the stack. Forced air is employed as the coolant. The aluminum foam used had an open-pore size of 0.65 mm and an after-compression porosity of 60%. Local temperatures in the stack and pumping power were calculated for various air-flow velocities in the range of 0.2–1.5 m/s by numerical simulation and were determined by experiments. This range of air speed corresponds to the Reynolds number based on the hydraulic diameter in the range of 87.6–700.4. Internal and external cells of the stack were investigated. In the simulations, and the thermal energy equations were solved invoking the local thermal non-equilibrium model—a more realistic treatment for airflow in a metal foam. Good agreement between the simulation and experiment was obtained for the local temperatures. As for the pumping power predicted by simulation and obtained experimentally, there was an average difference of about 18.3%. This difference has been attributed to the poor correlation used by the CFD package (ANSYS) for pressure drop in a metal foam. This study points to the viability of employing metal foam for cooling of fuel-cell systems.

Study on air foam flooding technology to enhance oil recovery of complex fault block reservoir by water injection

In order to solve the problem of rapid increase in water content and decrease in production after water flooding in fault block reservoirs, the air foam flooding experiments of static low temperature oxidation, single and double sand filled tube were carried out. The results showed that there was no absolute relationship between oxygen consumption and viscosity of crude oil, and there was a turning point of water saturation. The reaction rate is greatly affected by the reaction temperature. The displacement efficiency of single pipe is increased about 15%. The injection of air foam can effectively block the high permeable strip, and the middle low permeability layer is effectively utilized, and the recovery ratio is increased by about 10.9%. The plan of air foam flooding for Gao 16 block is compiled. The injection volume is 0.1PV and the gas-liquid ratio is 2:1. The recovery factor is increased by 5% and the cumulative oil increment is 22700 tons.

Foam-mat drying in the encapsulation of red sorghum extract: Effects of xanthan gum addition on foam properties and drying kinetics

Red Sorghum Extract (RSE) rich in proanthocyanidins (PA) was encapsulated in Arabic gum (AG), whey protein isolate (WPI), and xanthan gum (XG) to maintain its bioactive stability and dried by foam-mat drying. Xanthan gum was added as a stabilizer to maintain the stability of porous foam to accelerate the foam-mat drying (FD) in the encapsulation. This research investigated the effect of XG addition on the stability or quality of foam, its correlation on the parameter values of the empirical kinetics, and the mass transfer of FD. The research described that the air fraction, foam expansion, and foam overrun increased while the density decreased as a function of the whipping time in each XG addition. The XG addition increased the foam stability by WPI-XG interaction that inhibited their protein interactions. The quality-stability of foam affected the parameters of some empirical drying models and the moisture mass-transfer approach in two drying periods. The optimum foam structure was resulted by the XG addition of 0.5% on the RSE with 10% of WPI, 20% of AG at 15 min of whipping that resulted in 0.0016 /s of drying rate, and 1.617 × 10 −8 m 2 /s of the effective diffusivity. The empirical models and the mass transfer model approach showed high accuracy in predicting the FD. The drying was capable to retain 96.01% proanthocyanidins of the initial RSE, resulted in a powder containing 9.227 mg PA /mg powder with a yield of 16.24% (wet basis) and 99.96% (drybasis). It presented the excellent performance of FD in encapsulating RSE.

Porous metakaolin-based geopolymer granules for removal of ammonium in aqueous solution and anaerobically pretreated piggery wastewater

This research investigates the applicability of porous metakaolin-based geopolymer granules as an adsorbent to removal ammonium in aqueous solution and anaerobically pretreated piggery wastewater. The air foam content in porous geopolymer preparation was varied at 0, 5, 10, and 15 wt%. The porosity, water adsorption, average pore width, and total pore volume were found positively correlated with air foam content. The ammonium removal efficiency and air foam content were also positively related. The 15 wt% foamed geopolymer (GF15) provided highest ammonium removal efficiencies and adopted as the granular adsorbent. The maximum ammonium adsorption capacity of GF15 geopolymer granules was 47 mg g−1. It was obtained at pH 6.4, 30 °C, 24 h contact time and initial ammonium concentration of 2000 mg L−1. The adsorption kinetic data followed the pseudo-second-order model, with adsorption equilibrium condition reached within 120 min. The GF15 geopolymer granules could be reused multiple times after desorption with 0.2 M NaCl and 0.3 M NaOH. The GF15 geopolymer granules achieved 84% ammonium removal efficiency for anaerobically pretreated piggery wastewater having 75 mg L−1 ammonium initial concentration. The results demonstrated high selectivity toward ammonium ion of the porous geopolymer granules even with the presence of organic compounds and competing ions. This research demonstrates the application of porous geopolymer granules with tailored macropore structure for effective removal of ammonium ion from piggery wastewater.

EFFECT OF NONI FRUIT EXTRACT ON THE INTERNAL QUALITY, FOAM INDEX, AND HAUGH UNIT OF THE CHICKEN EGGS

This study aimed to determine the effect of noni fruit extract on the internal quality, foam index, and haugh unit of layers eggs. This research has been carried out at the Chemistry Laboratory of Widya Mandira University Kupang, and the Laboratory of the Faculty of Agriculture, University of Timor, Kefamenanu during February 12, until March 25, 2020. This study used eggs of layer chicken, each treatment using 25 eggs. The method used was a completely randomized design with a one-way pattern consisting of 5 treatments and 5 replications. The treatments given were T0 (control), T1 (2 ml noni fruit extract), T2 (4 ml noni fruit extract), T3 (6 ml noni fruit extract), and T4 (ampicillin). The variables observed were egg weight, air sac diameter, albumen height, egg yolk index, foam leakage, foam index, and Haugh unit. The results of statistical analysis showed the effect of noni fruit extract on egg weight, air sac diameter, foam leakage, foam index, and Haugh unit value. The mean value of each variable showed that the 6 ml (T3) noni extract treatment was better than the other treatments (T0, T1, T2, and T4). It was concluded that to maintain egg quality for up to 21 days, could be preserved with a concentration of 6% noni fruit extract.

The research of compressibility of compressed air foam

The compressibility of compressed air foam was an important mechanical parameter in hydrodynamic calculations. The compression coefficient was set by the theoretical model in the current study of foam computational fluid mechanics. Here are many types of fire foam and each of them is different with different compressible performance. The compression coefficient obtained by theoretical calculation has a certain error and the experimental method test is needed. In this study, the equipment for measuring the foam compressibility was designed and developed. The compressibility of compressed air foam was preliminary studied in this article.