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Summary Myofibrillar proteins (MP) and two forms of nanocellulose (cellulose nanofibers [CNFs] and cellulose nanocrystals [CNCs]) were used to prepare oil‐in‐water emulsion. The effect of CNFs and CNCs on the properties of pork MP‐lard emulsion was studied by analysing the emulsion index, microstructure, oil droplet size, zeta potential and rheological behaviour of emulsion. The results showed that both CNFs and CNCs improved MP‐lard emulsion stability. At the same nanofiber concentration, the creaming index of CNFs stabilised emulsion was lower than that of CNCs stabilised emulsion, especially at the concentration of 0.5%, emulsion prepared with CNFs has no phenomenon of creaming index, while emulsion prepared with CNCs still has creaming index phenomenon. At the same nanofiber concentration, the oil droplet distribution of CNFs stabilised emulsion was more uniform, especially at low concentrations (≤0.5%). At higher cellulose concentration (≥0.75%), the particle size of CNFs stabilised emulsion was larger than that of CNCs stabilised emulsion. CNFs stabilised emulsion had a higher zeta potential and modulus than that of CNCs stabilised emulsion and the emulsion formed by CNFs was more viscoelastic.
Abstract To achieve a stable addition of foaming agent under high flow rates, an independently designed venturi structure with self‐suction of liquid to add foaming agent was numerically simulated. We simulated the effects of different self‐suction liquid structures' diameters (diameter of the tube in which the liquid is sucked in), contraction angles, throat length, and position on the suction liquid ratio (ratio of venturi self‐suction liquid flow rate to total flow rate), compared and analyzed the data, and determined the optimal self‐suction liquid structures parameters. The suction liquid ratio shows a tendency to first stabilize and then decrease as the outlet pressure increases. When the outlet pressure in range of 0.30–0.45 MPa, the suction liquid ratio remains stable at 1.14%. However, as the outlet pressure increases, the ability of the venturi structure to add foaming agent through the self‐suction liquid decreases under high flow rates, causing the suction liquid ratio to rapidly decrease to a minimum value of 0.60 MPa. We have conducted a detailed analysis of the process and flow field of suction liquid. As the outlet pressure increases, the high‐speed area of the throat gradually shrinks, and the flow field in the diffusion section fluctuates. When the outlet pressure is 0.6 MPa and the velocity field shifts toward the upper part of the diffusion section, the cavitation area will gradually disappear and lose its liquid suction ability.
The practical utility of bismuth and tin compounds, as promising green combustion catalysts, is constrained by their substantial particle agglomeration. Herein, we reported a straightforward ultrasonication-assisted method to incorporate bismuth and tin compounds into the inner spaces of carbon nanotubes (CNTs), giving CNTs-confined bismuth (tin) compounds. The as-prepared nanocomposites were structurally completely characterized. The electrochemical property investigations showed that the introduction of bismuth and tin compounds increases the catalytic active sites of carbon nanotubes and inhibits nanoparticle agglomeration effectively. The theoretical calculations revealed that synergistic effects between Bi2O3 and carbon nanotubes can improve the efficiency of electron transfer in the Bi(NO3)3@A-CNTs(M1) composite. The evaluation results of the combustion catalytic performance of the nanocomposites on ammonium perchlorate (AP) pyrolysis suggested that adding 5 wt. % Bi(NO3)3@A-CNTs(M1) and DBT@A-CNTs(M1) (DBT = Dibutyltin dichloride) in AP brought about a more concentrated thermal decomposition process, advancing the peak of AP in the high-temperature decomposition stage from 420.4 °C to 328.9 and 325.9 °C, respectively, and boosting its heat release from 976.42 J·g-1 to 2251.2 J·g-1 and 2452.03 J·g-1, respectively. The studies on the thermal degradation mechanism of AP, probed by thermal decomposition kinetics, in-situ solid FTIR and TG-FTIR-MS, concluded that the electron transfer from the critical steps ClO4- to NH4+ and O2 to O2- is accelerated by the interaction of the in-situ formed Bi2O3 nanoparticles and carbon nanotubes, boosting the relative contents of more stable gases, and ultimately promoting AP pyrolysis. A tentative catalytic thermal degradation mechanism of AP is finally proposed.
Abstract Confined space fires could easily cause serious casualties and property damage, and foam is an effective means of preventing confined space fires. The existing foam generator does not have both momentum and foam expansion rate (FER) and is poorly suited to confined spaces. In order to develop a foam generator suitable for confined space fire protection, an in-depth analysis of the physical foaming characteristics of self-suction foam is required, and the structure of the foam generator is optimized accordingly. For this reason, this paper analyzes the foaming characteristics and forming principle of air self-suction foam generator, and simulates and studies the over-current ratio of rectifying orifice plate with the help of Fluent software, φ (the ratio of the area of the fluid that can pass through the rectifier disk to the vertical cross-sectional area of the fluid flow), the distribution patterns of flow field, pressure, and turbulence intensity inside the foaming machine are determined by the nozzle cavity spacing and mixing cavity diameter. The study demonstrates that water flow is the most effective means of entraining air, and that the contact between the fluid and foam network is most thorough when the overflow ratio of the fan disc (φ) is 0.455, the distance between nozzle cavities μ (the distance between the nozzle and the closest end face of the foam chamber vertically.) is 200 mm, and the diameter of the mixing chamber (d) is 260 mm. These conditions are optimal for the foam generator. Experimental verification shows that the device has the strongest air entrainment capability at φ 0.455. The foam mesh number (m), foam mesh spacing (l), and number of layers of foam mesh (n) significantly impact the air self-solution foaming of the jet. These factors influence FER, range (L), foam stacking thickness (σ), and unfoamed liquid separation rate (γ, Foam solution not involved in the foaming process.), but the magnitude of their effect varies. Considering the four factors affecting foam production performance, the optimal effect is achieved when the foam mesh of 16, the foam mesh spacing of 3 cm, the foam mesh of 2 layers, the distance between the foam mesh and the nozzle is 22 cm and φ is 0.455. Under these conditions, the foaming ratio (FER) of the jet self-suction foaming machine is 42 times, with L at 13 m, σ at 7 cm, and γ at 0.15 L/s. A device has been developed for long-distance and high FER air self-suction of foam generator, which can significantly assist in fire prevention and extinguishing in confined spaces.
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