Different Types Of Foam Research Articles

Foam detection in a stirred tank using deep learning neural networks

A deep learning method based on the Convolutional Neural Network (CNN) U-Net architecture has been explored as an image analysis tool for the detection and automated quantification of foam generated in a stirred tank. Multiple datasets of different sizes and with different types of foam were obtained experimentally and processed with data augmentation techniques in order to train the deep learning networks. The impact of adding attention and residual gates to the U-Net model to improve its performance, as well as the size of the dataset used to train the model have been assessed. The main factor influencing the accuracy of the models to detect the foam in the stirred tank is the size and quality of the dataset use to train the U-Net models; it must be sufficiently large and varied in terms of foam type/structure. The addition of attention gates and residual blocks to the U-Net model slightly improves the accuracy of foam detection, particularly for images that contain additional objects or obstructions, however the training time is 30 % longer than the standard U-Net model. In all cases, this image analysis method based on the U-Net model largely out performs conventional image analysis, which was not able to automatically differentiate between foam, additional objects in the tank and bubbles in the liquid. Two methods for the measurement of foam quantity (maximum foam height and foam volume) have also been developed based on the foam regions detected by the models. This is important for the application of the tool, which is to be used to understand the impact of operating conditions on foam formation in lab-/pilot-scale stirred tanks and then develop scale-up guidelines for foam control in industrial tanks.

115 Laboratory Performances of the CIP 10 Personal Aerosol Sampler for the Collection of Submicron Particles

Abstract The CIP 10 is a personal aerosol sampler designed to sample conventional dust or specific occupational inorganic or organic substances such as crystalline silica, isocyanates or mycotoxins. It is widespread used, especially in France. Within the CIP10, the rotating cup contains a porous polyurethane foam devoted to the collection of airborne particles and rotates inside its housing at a speed close to 6700 rpm to induce a 7 or 10 L/min sampling airflow, depending on the particle-size selector. Despite several published works regarding its physical performances, no experimental data exist regarding the sampling efficiency for submicron particles. This study aimed to measure the collection efficiency of the CIP 10 for different types of foam (60 or 75 ppi, functionalized or not) and for the three selectors (inhalable, thoracic, respirable). Polydisperse particles with aerodynamic diameters between 20 nm and 10 µm were produced using various generators and different materials (DEHS, glass beads) in a specific test rig. For a given diameter, the collection efficiency was calculated by comparing the number concentrations measured alternatively upstream and downstream of the rotating cup, using APS (TSI 3321) or SMPS (Grimm DMA Vienna Type, CPC 5.403) spectrometers. While collection efficiency was 100% for particles > 3 µm, it progressively decreased to around 50 % and even below 10 % for aerodynamic diameters of 800 mm and 150 nm, respectively. Collection efficiency was unaffected by the type of foam or sampler flow rate used. Bias maps and consequences on workers aerosol exposure assessment will be discussed.

Vibration characteristics of arbitrary thick sandwich beam with metal foam core resting on elastic medium

An analysis is performed in this research to obtain the natural frequencies and mode shapes of a thick sandwich beam with metal foam core. Different types of foams are considered for the sandwich beam where distribution of pores is a functionally graded patterns. The governing equations of the sandwich beam are established by means of a shear and normal deformable thick beam model. This theory considers the thickness stretching and admits the nonuniform through-the-thickness shear strain. The governing equations of the sandwich beam are established which are four in number by means of the Hamilton principle. The established equations are solved for the case of thick sandwich beams resting on elastic foundation via the Navier solution method. Results of this study are first compared with the available data in the open literature and after that novel results are given to explore the effects of different parameters on the vibration characteristics of the sandwich beam. It is shown that porosity of the core is an important factor on vibration characteristics of sandwich beam with metal foam core.

Experimental Research on the Effectiveness of Different Types of Foam of Extinguishing Methanol / Diesel Pool Fires

ABSTRACT Storage tank fire can pose great threats to life and environment as it can cause strong radiant heat, fast-spreading flame, and destructive explosion. In this research, a 1.5 m-diameter circular steel pan is used to simulate the full surface fire of a storage tank in an industrial park. A self-built fire-extinguishing system gently releasing foam at the rate of 11.4 L/min was applied for the evaluation of the effectiveness of different types of foam of extinguishing diesel/methanol pool fires. Experiments were conducted to analyze the temperature increases of fires after releasing different types of foam. In this research, the nondimensional average temperature 0.85 and 0.71 regard as the fire extinguishing temperatures of methanol and diesel fuel, respectively. Over the spreading process, the increase in foam spreading length over time still follows the power law. The fastest flow velocity of 6% FP/AR in methanol pool fire and 6% Synthetic foams in diesel pool fire was 0.0136 m s −1and 0.044 m s −1, respectively, with a foam application rate of 11.4 L/min. The results show that, in the methanol pool fire, the cooling effect of the foam is ranked as FP/AR > AFFF > AFFF/AR > S > FP > S/AR. And the cooling effect of foam for diesel is ranked as S > S/AR > AFFF > AFFF/AR > FP > FP/AR. Foam’s cooling impact is especially notable in diesel pool fires. As for methanol pool fires, the foam extinguishing mechanism is mainly based on the “anti-soluble film” effect, which quickly forms a covering layer on the surface of the flammable liquid, seperating the flame from heat feedback and inhibiting the generation of flammable vapors, insulating itself against the air and ultimately asphyxiating the fire.

Foam based fracking in unconventional shale reservoir

As the energy demand increases globally, oil and gas industry has started to explore the unconventional shale resources. Shale gas production has become feasible by the application of hydraulic fracking technology which involves the process of injecting water, chemicals and sands at high pressure to create small fractures within tight shale formations to stimulate the production. But the major problem using hydraulic fracturing involves excessive water consumption, formation damage etc. but, fracking methods with low water consumption viz., foam based fracking and nanoparticles based foam fracking are novel and much effective techniques for unconventional shale resources are discussed in detail in the present paper. When nanoparticles are added in the foam, it acts as proppants and enhances the quality of fracturing fluid rheology. The present paper discusses the foam characteristics and its proppants carrying capacity, reviews recent studies on different types of foam based fracking, and nanoparticles stabilized foam fracking. Experimental studies, field applications, its major advantages and disadvantages are also discussed.

Effect of multi-layer prosthetic foam liner on the stresses at the stump–prosthetic interface

The prosthetic liner plays a significant role in the redistribution of the pressure between the stump and the socket, as it adding a cushioning layer between the stump and the socket which relieves pain and makes the prosthesis more comfortable. This study employed nonlinear finite element analyses to investigate the peak pressure and shear stress at stump–prosthetic interface in the case of multi-layer prosthetic foam liner, this liner having an inner polymeric foam layer Surrounded by another type of polymeric foam layer, we used three different types of foams in different order to define this liner (flexible polyurethane foam, polyurethane-shape memory polymer foam, and natural rubber latex foam). That’s allows comparing 6 deferent configuration of multi-layer prosthetic foam liner.

Compression and tension behavior of the prosthetic foam materials polyurethane, EVA, Pelite™ and a combination of polyurethane and EVA: a preliminary study.

Materials with low-strength and low-impedance properties, such as elastomers and polymeric foams are major contributors to prosthetic liner design. Polyethylene-Light (Pelite™) is a foam liner that is the most frequently used in prosthetics but it does not cater to all amputees' limb and skin conditions. The study aims to investigate the newly modified Foam Liner, a combination of two different types of foams (EVA+PU+EVA) as the newly modified Foam Liner in terms of compressive and tensile properties in comparison to Pelite™, polyurethane (PU) foam, and ethylene-vinyl acetate (EVA) foam. Universal testing machine (AGS-X, Shimadzu, Kyoto, Japan) has been used to measure the tensile and compressive stress. Pelite™ had the highest compressive stress at 566.63kPa and tensile stress at 1145kPa. Foam Liner fell between EVA and Pelite™ with 551.83kPa at compression and 715.40kPa at tension. PU foam had the lowest compressive stress at 2.80kPa and tensile stress at 33.93kPa. Foam Liner has intermediate compressive elasticity but has high tensile elasticity compared to EVA and Pelite™. Pelite™ remains the highest in compressive and tensile stiffness. Although it is good for amputees with bony prominence, constant pressure might result in skin breakdown or ulcer. Foam Liner would be the best for amputees with soft tissues on the residual limbs to accommodate movement.

GC-FID and Olfactometry-Assisted Assessment of Odors from Polymeric Foams under Normal and Repeated-Use Conditions

Polymeric foams are the primary components of upholstered furniture, and their emissions play a decisive role in the acceptability of the final furniture product. This study is focused on passive emissions and odors from commercial foams under normal and repeated-use conditions. Six different types of foams, viz., highly elastic foam K5040, standard PU foam N5063, bonded polyurethane foam R100, viscoelastic foam V5020, self-extinguishing foam KF5560, and foam rubber, were used. The samples were collected at the intervals of 72 hours and 672 hours (28 days) to identify the odors due to chemical reactions in the material or slowly released due to its porous structure. Additionally, repeated-use studies were done to understand the effect of prolonged usage/natural ageing on emitted odors from the foams. The samples were tested as per ČSN EN 13 725 (2005) and ISO 16000-6 (2011) criteria using GC-FID (gas chromatography-flame ionization detector) and olfactometry. The most unpleasant substance was found to be nonanal, with an average score of -4 (unpleasant). A total of 23 compounds were identified (5 unidentified) using olfactometry; however, only 11 of them were confirmed by GC-FID-based testing. Any new compound or increase in odor intensity was not observed in long-term measurements and simulated repeated-use conditions.

Visualisation of stabilising particles at the gas-solid interface of metal foams

In this article, we demonstrate a technique to visualise the stabilising particles at the gas-solid interface of metal foams by employing metallographic etching. This technique is easy to perform and can be applied on a relatively large sample size. The particles present at the gas-solid interface of five different types of foams were investigated. Information on the type of particles and the particle coverage could be obtained from this study.

Structure and swelling of cross-linked nanocellulose foams

HypothesisThe water absorption capacity of nanocellulose (NC) foam is tailored by crosslinking with polyethyleneimine (PEI) and hexamethylenediamine (HMDA). The interaction of amine groups in PEI and HMDA with the carboxylic groups (COO−) of NC affects the foam structure which reduces its swelling capacity. ExperimentsFunctionalised NC foams were prepared by TEMPO (2,2,6,6,-tetramethylpiperidine-1-oxyl) oxidation of bleached pulp, followed by fibrillation into a hydrogel, adding a crosslinker and freeze drying the hydrogel into a foam. The structure of the NC foam characterised by rheology, SANS (Small Angle Neutron Scattering), SAXS (Small Angle X-ray Scattering) and cryo-SEM (cryo-Scanning Electron Microscopy) was related to absorption and swelling properties. FindingsThe NC foam has the highest water absorption capacity at 132 g water/g foam. PEI-NC foam has a water absorption capacity of 71 g water/g foam, which further decreases to 47 g water/g foam for the HMDA-NC foam. Small angle scattering reveals the elementary fibril of NC is 3–5 nm thick and forms fiber bundles. In water, these bundles swell differently for the different types of foam which affects the water absorption capacity of the network. The structural analysis of the foam was related to the swelling capacity. The structure of NC foam can be engineered for specific applications for biomedical, agriculture or food industries.

Estimation of Volatile Organic Compounds (VOCs) and Human Health Risk Assessment of Simulated Indoor Environment Consisting of Upholstered Furniture Made of Commercially Available Foams

This study was conducted for the qualitative and quantitative determination of volatile organic compounds (VOCs) and total volatile organic compounds (TVOC) from polymeric foam materials used in upholstered furniture. Six different types of foams viz. Highly elastic foam K5040, standard PU foam N5063, bonded polyurethane foam R100, viscoelastic foam V5020, self-extinguishing foam KF5560, and foam rubber were used. Short-term and long-term (24, 48, 72, 672 hours (28 day)) measurements were done to differentiate the role of primary emissions (present in new products) and secondary emissions (due to chemical reactions in material or slowly released due to the porous structure of material). The samples were collected using a small-space sampling chamber at a temperature of 23°C and a humidity of 50% depending on the aspect of time. The concentrations of VOC and TVOC were identified and quantified using a Gas chromatography–Mass spectroscopy (GC-MS) based method. Based on the VOC measurements, the standard room concentrations were simulated to estimate the human health risk assessment for all six types of foams. The results of simulations suggest no possibility of human health risk for the very long period (28 days), as the estimated values were found to be much below the prescribed limits.

Measurement and analysis of sound absorption by a metallic composite foam

A composite foam consisting of polyurethane foam embedded in metallic foam is fabricated and evaluated for sound absorbing properties. The normal incidence sound absorption coefficient is measured in an impedance tube for three different types of foams including the composite foam, a rigid framed metallic foam, and an elastic framed polyurethane foam. A lumped element model is used to predict the energy dissipation mechanisms, which include viscous and thermal losses, structural losses, and coupling losses at the metal and polyurethane interface. The best performing composite foam increased sound absorption by a factor of 6 (from 0.1 to 0.6) in the low frequency test range (around 600 Hz) and by a factor of 2 (from 0.2 to 0.4) over the entire test frequency range (250–4500 Hz). The composite foam maintains the high static stiffness of the metal foam and exhibits acoustic compliance characteristic of the polyurethane foam. Composites such as those presented in this work are advantageous for engineering applications where combined high stiffness and energy absorption are required.

Foamability in high viscous non-Newtonian aqueous two-phase systems composed of surfactant and polymer

Foaming in high viscous and non-Newtonian aqueous phase is generally difficult to be realised. In this work, a surfactant (Sodium Linear Alkylbenzene Sulphonate with alkyl chain lengths varying from C10 to C16) named LAS paste mixed with a co-polymer solution of acrylic acid and maleic acid denoted by Polymer solution was used to generate foam under conditions of sparging without or with agitation, which aims to be used as a coating material of detergent powders. The foam structure/morphology, bubble size, gas holdup and liquid drainage in such surfactant-copolymer system were investigated. It was found that two different types of foam were generated: 1) dispersed spherical air bubbles in highly viscous mixtures of LAS paste and Polymer solution with median size d50 in a range of 20–50 μm and gas holdup of 0.20 - 0.44 depending on LAS concentration, 2) bubbles with polyhedral structure in a mixture of LAS paste and Polymer solution diluted with water and size d50 = 7.0 ± 0.4 mm and gas holdup of 0.93 ± 0.05. The generated foam structures depended on the energy input, air superficial velocity, surfactant concentration and the liquid viscosity. Besides, they even depended on liquid mixing procedures before the foam was generated, resulting from different transfer rates from LAS paste phase to Polymer solution. The comparison of foam behaviours in such complex system and in single-phase liquid was made. For dispersed spherical bubbles, the median size has been correlated to energy input whilst for bubbles with polyhedral structure the characteristic size has been predicted by considering the balance between their buoyancy and viscous forces generated in the system. Based on the results, the mechanism of foam stabilisation is proposed.

Multiscale characterisation and simulation of open cell metal foams

AbstractThe complex microstructure of open cell metal foams results in beneficial global material properties like a good weight to stiffness ratio, which makes this special group of cellular materials interesting for several applications. Open cell metal foams are suitable for lightweight applications as well as for energy absorbing systems. The dependency of the entire samples' mechanical behaviour on their microstructure induces the demand of experiments and simulations on different scales. Hence, a couple of experiments are necessary to specify the material properties of open cell aluminium foams. On the macroscopic level, several tests with different load cases such as pure tension, pure compression or pure torsion and the superposition of these loading conditions are needed to obtain the yield surface for the different types of foams. The material parameters on the microscopic level can be identified by microtensile tests and inverse calculations using a 3D model of the strut. The deviation of the simulation results from the experimental data is minimised by an optimisation. Thus, the used material parameters in the simulations are changed until the numerical results match the experiments. This contribution focuses on the characterisation of open cell metal foams on different hierarchical levels. It introduces an approach to describe the macroscopic material behaviour with a homogeneous material model based on micromechanical experiments and material parameters.

Foamability of fatty acid solutions and surfactant transfer between foam and solution phases

The foaming properties of aqueous solutions of fatty acids with different hydrocarbon chain lengths - hexanoate, laurate, and oleate - were assessed through measurements of foam volume and growth rate under continuous aeration. Simultaneous measurements of the partition of each surfactant between the bulk solution and foam phases were also carried out. Although bubble size measurements in bulk solution pointed towards quite similar gas dispersing abilities of the tested surfactants, their foamabilities under the same conditions were remarkably enhanced with increasing chain length of the hydrocarbon tail. Shorter chain surfactants - hexanoate and laurate - generated wet foams and the accumulation of these surfactants in the foam phase was very low, indicative of a low adsorption density of the reagents at the gas-liquid interface. In contrast, sodium oleate produced stable dry foams, and the amount of oleate transferred to the foam was much higher. The formation of these different types of foam was attributed to the higher adsorption of oleate at the gas-liquid interface compared to the lower adsorption of hexanoate or laurate, and to different mechanisms of foam stabilization. Regardless of the interfacial mechanism of the foaming action of the tested surfactants, it was generally found that strong foaming was possible only from surfactant solutions whose bulk concentration was higher than the critical coalescence concentration of a given surfactant. It was concluded that bubbles entering the foam phase from the bulk solution phase must already be stable against coalescence to induce foam formation and impart stability to the entire foam column. Foaming was observed only in true solutions of the tested surfactants, while precipitation of colloidal acid species completely depressed foam formation.

Experimental study on stability and rheological properties of aqueous foam in the presence of reservoir natural solid particles

Gas injection and especially CO2 flooding has been applied in many oil reservoirs globally to increase oil recovery factor in addition to its environmental friendly aspects. However, difference between fluid viscosities and densities, can cause interface instability where gas override and fingering may expedite gas breakthrough. Different types of foam have been proposed to improve interface stability. Yet, a major uncertainty is interaction of foam with natural reservoir particles which may improve or downgrade the performance and stability of foam. In this study we examined foam stability through solid-fluids interactions between solid particles of hydrocarbon reservoirs and aqueous foam. We tested five common reservoir particles of calcium carbonate, calcium sulfate, barium sulfate, strontium sulfate and iron oxide with different surfactant and particle concentrations. It is found that stability of foam in the presence solid particles is a function of density, shape, size, and wettability of particles where monolayer, bilayer of network or particles stabilise foam lamella or rupture foam structure. Results show that solid particles of calcium carbonate, barium sulfate and strontium sulfate enhance the thermodynamic stability of foam. This is due to the distribution of semi-hydrophilic solid particles, which form mono- and multi-layers of particle chains in foam lamellae and plateau borders. On the other hand, solid particles of iron oxide and calcium sulfate destabilise foam where particle swelling, adsorbed surfactant solution and settlement into liquid phase due to their high densities were observed. The results suggest that a comprehensive study of liquid and solid interaction is critical in design of any foam for enhanced oil recovery processes.

Mixed-Mode Testing for an Asymmetric Four-Point Bending Configuration of Polyurethane Foams

Many efforts have been made recently to determine the fracture toughness of different types of foams in static and dynamic loading conditions. Taking into account that there is no standard method for the experimental determination of the fracture toughness of plastic foams, different procedures and specimens were used. This paper presents the polyurethane foam fracture toughness results obtained experimentally for three foam densities. Asymmetric four-point bending specimens were used for determining fracture toughness in mode I and in a mixed one, and also the influence of the loading speed and geometry of the specimen were investigated.

Impact and energy absorption of portable water-filled road safety barrier system fitted with foam

Portable water-filled barriers (PWFBs) are roadside appurtenances that are used to prevent errant vehicles from penetrating into temporary construction zones on roadways. A numerical model of the composite PWFB, consisting of a plastic shell, steel frame, water and foam was developed and validated against results from full scale experimental tests. This model can be extended to larger scale impact cases, specifically ones that include actual vehicle models. The cost-benefit of having a validated numerical model is significant and this allows the road barrier designer to conduct extensive tests via numerical simulations prior to standard impact tests. Effects of foam cladding as additional energy absorption material in the PWFB were investigated. Different types of foam were treated and it was found that XPS foam was the most suitable foam type. Results from this study will aid PWFB designers in developing new generation of roadside structures which will provide enhanced road safety.

Experimental Research of Integrated Compressed Air Foam System of Fixed (ICAF) for Liquid Fuel

This article in view of the realistic requirement of fixed fire extinguishing system in the places of water-insoluble liquid, establishes stationary compressed air foam experiment platform in combination with the advantage of compressed air foam technology. Key component nozzle and mixing chamber of the system is designed. By cold spray test, obtains parameters of gas-liquid flow、pressure, foam mixing ratio which result in different types of foam. The division of different types of foam basis is put forward, and take drainage time as indicators, get the most stable foam parameter combination; by extinguishing experiment, get the better combination of dry foam and small nozzle whose extinguishing effect is best. The results can be guidance for production research of integrated compressed air foam and system application in combustible liquid places.

Refinements on fracture toughness of PUR foams

Many efforts have been made in recent years to determine the fracture toughness of different types of foams in static and dynamic loading conditions. Taking into account that there is no standard method for the experimental determination of the fracture toughness of plastic foams different procedures and specimens were used. This paper presents the polyurethane foam fracture toughness results obtained for different foam densities. Two types of specimens were used for determining fracture toughness in modes I, II and a mixed one, and also the size effect, loading speed and loading direction were investigated. The paper proposed correlations for density, cell orientation and mixed mode loading based on the experimental testing results.