EXTINGUISHING FIRES OF ALCOHOLS AND THEIR MIXTURES

The efficiency of carbon dioxide (CO2)-flooding in highly heterogeneous reservoirs may be low due to poor macroscopic sweep. One of the possible ways to increase macroscopic sweep efficiency is by reducing the CO2 mobility by foam. Retention of the foaming agent during CO2-foam flooding is an important aspect affecting both technical and economical potential of the process. This paper presents both experimental and numerical simulation studies performed to investigate the retention of CO2-foaming agents in heterogeneous carbonate reservoirs. These reservoir types consist of high permeable "thief zones" - fractures or high permeable layers and the rest of the reservoir - matrix or low permeable layers. The retention of CO2-foaming agent was studied in flow-through laboratory experiments with CO2-foaming agents; branched ethoxylated sulphonates with different ethoxylation degree in outcrop Liege chalk rock at 55°C. The retention of the foaming agents was determined by breakthrough curves based on chromatographic separation between the foaming agent and a tracer. The flow-through retention experiments were reproduced in a numerical simulator. The results indicate that the retention (the amount of foaming agent lost per rock weight) depends on the type of foaming agent and oil saturation. It is concluded based on simulation results that the amount of the foaming agents retained in heterogeneous reservoirs would strongly depend on its transfer mechanism from high into low permeable zones. The diffusion process is slow and therefore the foaming agent might penetrate only into a certain fraction of the matrix blocks or low permeability layers during the project life time. The retention of the foaming agent in these heterogeneous carbonate reservoirs may therefore be much lower than estimated based on viscous floods. A numerical model describing diffusion and retention by adsorption was established. A good match between experimental and modeling results was obtained without individually tuning the numerical model for each specific experiment. Additional simulation results showed that on the field scale the amount of foaming agent retained in heterogeneous reservoirs will depend on the number of high permeable zones and the size of the matrix blocks.

Authigenic gas foaming hydrogels were synthesized using chitosan (CS), acrylic acid, and attapulgite (APT) as hydrophilic monomers; potassium persulfate as initiator; N,N′-methylenebisacrylamide as cross-linker; and sodium carbonate (Na2CO3)/acetic acid as foaming agent. Effects of different monomers, amount of foaming agent, and temperature on swelling ratio (SR) of the hydrogels were examined. Morphology, structure, and thermal stability of authigenic gas foaming hydrogels were studied using field emission scanning electron microscope, Fourier-transform infrared spectroscopy, and synchronous thermal analysis. Scanning electron microscope images reveal apparent pores on hydrogels, produced by foaming agent Na2CO3/acetic acid. Therefore, more foaming agent would bring more pores on hydrogels. Synchronous thermal analysis results suggest that higher amount of CS would result in higher thermostability of hydrogels. However, APT has no substantial effect on thermal stability. SR decreases with increasing amount of CS. Hydrogels prepared at 70°C reaction temperature exhibit maximum swelling. Furthermore, SR decreases with higher covalence of saltion.

Assessment of morphological characteristics and physico-mechanical properties of geopolymer green foam lightweight aggregate formulated by microwave irradiation

Closed-cell A356 aluminum foams have been produced by the addition of calcium carbonate (CaCO3) powder as a foaming agent to the molten aluminum without any stabilizer particles. The foaming process is performed by the addition of 2.5–3.5 wt% CaCO3 and has relative density ranges of 0.12–0.44 and cell sizes of 1.5–3.1 mm with uniform cell structures. The foaming stabilizing mechanism and effect of foaming conditions such as the amount of foaming agent, casting holding and mixing time at the furnace on the foamed samples were investigated. The stabilizing mechanism is because of the foaming gas (CO2)/melt reaction during the foaming procedure and producing some solid particles such as CaO, Al2O3 and MgO. The optimum foamed aluminum with uniform cell size distribution was obtained at 4-min mixing time and 10-min holding time with 3 wt% CaCO3 foaming agent. The porosity of aluminum foam increased as the holding time increased from 60 to 86%. Also, the average cell size increased from 1.5 to 3.1 mm when the amount of CaCO3 increased from 2.5 wt% to 3.5 wt%, respectively.

Recent years have seen researchers paying attention to the fabrication of porous structures by using additive manufacturing techniques suitable for the production of small batches. This paper focuses on the fabrication process and the compressive characteristics of a porous metal manufactured using the direct energy deposition (DED) process, which is a 3D printing technology for metals. Materials with structures containing internal pores were manufactured by spraying a mixture consisting of Ti6Al4V powder and a foaming agent (Na2CO3) onto a Ti6Al4V substrate, and subsequently fused with the substrate using a high-power laser beam. The ensuing molten pool undergoes rapid solidification, resulting in the formation of a metal layer. Before the molten metal solidifies, the carbon dioxide gas generated from Na2CO3 created pores inside the deposited layer. In this study, pored structures fabricated under various conditions were analyzed and compared from the viewpoint of compressive behavior. The results showed that the densities of the layered porous structures could be controlled by varying process parameters such as the laser power, scanning speed, powder feed rate, and mix ratio of the foaming agent. The most dominant parameters to obtain a pored structure were the amount of foaming agent and powder feed rate. The compression tests revealed that the porous materials manufactured using DED collapsed due to fracturing of the internal porous structures. After these structures fractured, the materials experienced densification, followed by crumbling. In addition, decreasing the laser power and scanning speed caused the compressive strength to decrease due to the high number of internal pores. Furthermore, before finally fracturing, the compressive strain decreased for specimens with increased porosity. The compression tests proved that the porous structure was able to effectively absorb compression loads.

Eco‐friendly glass foam (GF) with a specific mechanical strength of 5.96 MPa g−1 cm3 and thermal conductivities between 0.131 and 0.282 Wm−1 K−1 was produced using fluorescent lamp glass residue (FLGR) and white eggshell as foaming agent (FA). The influence of the FLGR average diameter particle, the amount of FA, and the heat treatment on the GF final properties were evaluated. The highest expansion (500%) and the lowest density (0.24 g cm−3) were achieved using 32.90 μm mean diameter FLGR particles, 5 wt% FA, and foaming at 700°C. The produced GF showed promising application as porous building materials with load‐bearing function.

Fabrication of Lightweight Foam Glasses for Thermal Insulation Applications

The present study was planned to study the influence of Rice Husk ash (RHA) on fresh and hardened properties of foamed concrete. The percentage replacement levels of RHA for fine aggregates (FA) were 0%, 5%, 10%, 15% and 20%. Production of light weight concrete was carried out with foam which was produced indigenously using a foaming agent (Foamtech). The theoretical density of foamed concrete containing 0% replacement level of Rice husk ash (RHA) was kept to be equal to 1300 ± 50 kg/m3. The actual density observed for foamed concrete containing 0% replacement level of RHA during experimental analysis was 1317 kg/m3. At curing age of 7, 14, 28, 56, and 90 days, the hardened foamed concrete cube specimens of size 100 mm × 100 mm × 100 mm were evaluated for compressive strength and 150 mm × 300 mm for split tensile strength. At a curing age of 28 days, the cube specimens were also examined for water absorption and dry density. For all of the foamed concrete mixes, the cement and fine aggregate content were kept the same. The water-cement ratio was maintained at 0.5. The only difference among all the mixes was the replacement level of RHA 5%, 10%, 15% and 20%. The amount of foaming agent was varied according to the replacement levels of RHA to ensure good workability of paste. All the results of various properties were compared with the control mix. It may be noted that 0% replacement level of RHA with FA has been considered a control mix. The maximum and minimum compressive strengths, split tensile strengths and dry densities were shown by control mix and mix containing 20% replacement level of RHA respectively. On the other hand, the minimum and maximum water absorption capacities were shown by control mix and mix containing 20% replacement level of RHA respectively.

Phenolic foam (PF) has excellent performance in fire resistance, thermal insulation and other fields. It has the advantages of lightweight, flame retardant, no dropping and low level of toxic gas emission during combustion. In order to learn the relationships between density and properties, PF samples with density of 40, 50 and 60 kg · m−3 were obtained by adjusting the amount of blowing agent. Their micro-characteristics were analyzed with Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) experiments. Mechanical properties were measured with universal extending machine. Thermal properties and stability were tested by laser thermal conductivity analyzer and thermogravimetry analysis (TG), respectively. FT-IR spectra of samples demonstrate that chemical structure will not be affected by the ratio of foaming agent. Higher density comes with better sealing property of the cell holes and leads to better compressive strength. Changing PF density with foaming agent dosage could affect insulation effect, and the sample with density of 60 kg · m−3 showed poor performance compared with the other foams. TG–DTG curves of the PF samples are similar. Evaporation of water, volatilization of phenols and aldehydes, and pyrolysis of surfactant and curing agents are the main reason for the mass loss. Residues of samples increased with the increase in density at 900 °C. Results of this study can clarify that changing the density of PF with amount of foaming agent will not affect its chemical properties, but the ratio has impact on its physical properties.

Comprehending the interplay between foam morphology, surface skin, geometry, and compressive behavior is fundamental to the design of advanced functional applications, including energy absorption (EA) systems, seismic mitigation devices, and Phase Change Materialheat storage units. The influence of sample shape (cylinder-CYL, triangular prism-TRP and square prism-SQP) on microstructural and compression behavior was investigated for ductile (AlMg1Si0.6 + 1% wt. ZrH2) and brittle (AlSi12Mg0.6 + 0.4% wt. TiH2) aluminum alloy foams (AAFs). The different compositions and foaming agents led to unique cellular structures. The AAFstructures exhibited heterogeneity, with variations between top and bottom parts of samples, but only small differences in pore numbers were observed. Total number of pores varied according to the cross-sectional shape, with CYLs having significantly more pores compared to TRPsand SQPs. Ductile AAFhad small round pores with thick pore walls, while brittle AAFs exhibited regions with dense and thin pore structures due to coalescence and collapse during foaming. Precursor composition significantly impacted AAF structure, surface skin thickness, and compression.Compression strength, plateau stress, and EA were shape-dependent: SQPs performed best for brittle AAFs, while CYLsamples showed higher ductile compression response and better EAin brittle AAFs. Densification strain was again observed independent on the sample shape, type of alloy, type and amount of foaming agent.

The foamability of iron‐carbon alloys using the powder metallurgical process route was investigated. Pure iron and carbon powder with an addition of foaming agent were mixed and compacted. The foaming process started during heating the sample as soon as a temperature above the solidus temperature of the iron‐carbon alloy was reached. Result of the process is an iron foam with a porosity of up to 60%. It was investigated, how the foaming behaviour is influenced by the parameters of alloy composition and compaction process. Different foaming agents (alkaline earth metal carbonates and metal nitrides) as well as different carbon additions and compacting processes were tested.It can be seen that sort and amount of foaming agent have an unexpected low influence on the expansion process whereas an increasing carbon content supports the expansion significantly. The use of different compacting processes has only little influence on the expansion itself, but highly effects both the pore distribution and homogeneity. The poor effect of the foaming agent cannot be satisfactorily explained. Investigations of a possibly premature gas emission or of a not gas‐tight inclusion of the foaming agent do not show clear results. The support of the expansion by carbon additions can be attributed to the formation of CO‐gas by the Vacher‐Hamilton law during simultaneous formation of the liquid Fe‐FeC‐eutectic phase. The more inhomogeneous pore structure of iron foams caused by the use of hot‐or hot isostatically pressed semi‐finished products can be traced back to a higher internal gas pressure in the sample which results in a burst of the microstructure of the semi‐finished product.

A multilayer material was produced by rotational molding to study the effect of composition on the mechanical behavior of a cylindrical liquid container. The first (outer) layer was a composite of linear medium density polyethylene (LMDPE) with 5, 10, or 15 wt% agave fiber (AF). The core (middle) layer was foamed LMDPE with different amount of foaming agent (0, 0.15, 0.25, 0.5, and 0.75 wt%). Finally, the third (internal) layer was neat LMDPE. This structure was produced to optimize the mechanical properties of the molded parts while decreasing weight with good surface properties. From the morphological analysis, it was observed that the layers are not always well defined because of gas migration, especially from the foamed core to the composite layer. As expected, density increased with fiber content while decreasing with foaming agent concentration. In general, impact strength (Charpy and Gardner) was directly related to the overall density of the part. POLYM. ENG. SCI., 56:278–286, 2016. © 2015 Society of Plastics Engineers

Intermetallic (Al-Ni) foams were fabricated by a combustion reaction of the blended powder compacts consisting of nickel and aluminum. The foaming agents (titanium and B4C powders) were added to the nickel and aluminum blended powder to produce foams with high porosity by increasing the combustion temperature. The effects of the size of elemental powders (aluminum and nickel), the powder blending ratio, the amount of foaming agent and compacting conditions on the porosity and pore morphology of the foams were investigated. The size of nickel powder was an important factor to produce foams by the combustion synthesis and it should be small enough to achieve high porosity. The size of the aluminum powder was not such an important factor. The uniform pore morphology in the foam was obtained only when the powder blending ratio was adequate. The proper addition of the foaming agent increased the porosity and the size of pores, and also stabilized the uniformity of the pore morphology. There was a threshold density of the precursor to achieve sufficient foaming. The pore diameter of a synthesized foam is increased with increasing precursor compacting temperature and pressure. An attempt was made to disperse fine ceramic particles in the foam materials. It was revealed that the addition of ceramic particles did not affect the porous structure.

Phosphorus slag could be used to prepare wollastonite glass ceramics. With the aid of incorporated foaming agent, foam glass ceramics can be obtained via the sintering of the slag-based glass. After the glass powder reacted with graphite, macro-size pores with homogeneous distribution were formed. The level of porosity of the fabricated foams was controlled by varying heat treatment temperature and amount of foaming agent. It was found that the preferential processing parameters for producing foam glass ceramics were foaming temperature of 1000°C with holding time of 10 min and 1 wt. % of graphite. In this case, the porosity reached about 80%. The results show that dominant crystalline phase is wollastonite, and the high compression strength results from the crystallization of glass during sintering process.

Development of lightweight porcelain stoneware tiles using foaming agents