The prediction accuracy for high-pressure hydrogen states during leakage or emptying shows significant dependence on ideal-gas and real-gas models. A computational framework integrating multiple representative equations of state (EOS) was therefore established to analyze dense hydrogen discharge thermodynamics from storage tanks. It is applicable to EOS not explicitly addressed in this study and can simplify the non-adiabatic release model into the adiabatic model. Comparative analyses of two high-pressure gaseous hydrogen release scenarios were conducted. Results demonstrate that non-adiabatic discharge processes show a closer alignment with experimental observations. Thermodynamic model using ideal-gas model fails to properly characterize high-pressure hydrogen discharge behaviors, while approaches based on the van der Waals EOS exhibit limited predictive accuracy. Comparatively, the thermodynamic model employing more advanced sub-model of cubic EOS or Helmholtz energy EOS maintains consistent performance, with deviations between its predictive and experimental data remaining within an acceptable range. The Abel-Noble EOS-based model shows particular advantages in formulation simplicity coupled with reliable predictive capability. This modeling framework effectively determines stagnation parameters and nozzle sonic states, thereby establishing accurate boundary conditions for high-pressure hydrogen leakage or emptying simulations.

Weather radar has become a vital tool for monitoring wildfire plume evolution and estimating emission source strengths. However, its quantitative application remains constrained by a limited understanding of the microwave scattering properties of wildfire smoke particles. This study characterizes the scattering behavior of three key particulate types released during wildfires: black carbon (BC), brown carbon (BrC), and coarse-mode pyrometeors. By integrating experimentally derived refractive indices into discrete dipole approximation and Mie theory, we quantitatively analyzed the microwave scattering characteristics of these particles. The calculation accounts for the horizontal orientation of pyrometeors, random orientation of BC, and orientation-independent scattering of spherical BrC. Results indicate that at microwave frequencies, BC exhibits a higher real part of the refractive index, while BrC displays a relatively larger imaginary part, indicating strong absorption. In contrast, although pyrometeors possess lower refractive indices than carbonaceous aerosols, they exhibit the highest single scattering albedo due to their significantly larger size parameters. Carbonaceous aerosols outnumber pyrometeors by similar to 4 orders of magnitude. Simulations confirm that this numerical advantage is offset by the massive similar to 11-order-of-magnitude advantage in the pyrometeor backscattering cross-section. Consequently, pyrometeors are the dominant source of radar reflectivity. While BC and BrC exhibit near-zero differential reflectivity (ZDR), pyrometeors display significantly elevated ZDR. Furthermore, the low-ZDR signature observed in upper plumes is consistent with the abundance of the lofted carbonaceous aerosols. These results provide essential dielectric and scattering parameters for improving wildfire plume microphysical retrievals.

Due to the increased risk of phosphate depletion, there is an increasing demand for low-phosphorus or bio-based phosphorus flame inhibitors. Therefore, two novel composites with biologically-based phosphorus sources that chelate transition metal ions were synthesized via assembly method, i.e., Mn-PMC and Ni-PMC, the structure and binding states of the composites were examined by SEM, TEM, FTIR, XRD, XPS, BET and TGA. The results indicated that Mn-PMC and Ni-PMC (i) are nanoscale materials with well dispersed, (ii) have an amorphous structure and have sites that bind to other substances, (iii) contain no halogen elements. Then the combustion inhibition experiments of downward flame spread and TG-IR-MS analysis revealed (i) that the inhibition efficiency of the two prepared inhibitors was higher than that of commercial phosphate-containing inhibitor ADP. Among them, Ni-PMC had the best suppression effect, and the flame of cellulose sample containing it would automatically extinguish after igniting with a smallest dosage, (ii) two inhibitors reduced the laminar flame velocity and flame temperature. (iii) their flame suppression mechanism was indicated as that the pyrolysis releases inert gas to dilute the free radical concentration. This work is helpful for the development of efficient transition metal fire extinguishing agents to replace traditional phosphorus resources.

With the rapid emergence of large open-plan architectural structures, there is a need to reevaluate the applicability of fire standards based on smaller compartment fire dynamics. More investigation is required to gain a deeper understanding of the associated fire characteristics. Therefore, this paper investigated experimentally and numerically the fire behavior and ceiling temperature distribution in a 1/4th-scaled large open-plan compartment with unilateral asymmetric openings, under several different-sized openings and fire sources. The results showed that an increase in the dimensions of the asymmetric openings positively impacted the combustion rate of the fire source and the flame inclination; the latter increased in the direction away from the opening. The previous classical models based on open confined spaces underestimated the maximum ceiling temperature, whereas the model relying on the virtual origins performed well. A critical opening size was found to minimize the buoyancy-driven plume component. Thus, a physical model suitable for predicting the longitudinal ceiling temperature distribution in large open-plan buildings was proposed, considering both the sizes of the fire source and openings. The new model demonstrated good agreement with experiments and improved understanding of fire dynamics in a large open-plan compartment with unilateral asymmetric openings.

During the production of vinasse fish, the taste and aroma undergo changes over with time. The flavor stems from the breakdown of proteins, whereas the scent arises from the oxidation of proteins and fats. Analysis across different processing stages showed an initial increase in free amino acids, peaking at 24.9 g /100 g on the 9th day (p < 0.05) followed by a decrease. The content of unsaturated fatty acids gradually increased as fermentation progressed. The electronic tongue proved effective in distinguishing distilled grain fish at various fermentation stages. GC-MS analysis of flavor compounds in distilled grain fish at different fermentation times revealed that the total number of flavor compounds initially increased and then decreased, peaking on the 9th day. Considering the changes in lipid oxidation and flavor over different fermentation periods, it was determined that the quality of distilled grain fish was optimal on the 9th day at 20 degrees C, with both the total amount of free amino acids and the variety of flavor compounds reaching their peak.

External concentric ring damage (CRD) on the front surface and internal filamentary damage (FD) of fused silica were simultaneously observed when a 355 nm nanosecond laser pulse was focused on the rear surface through the front surface. The diameter difference between the concentric ring on the front surface and the laser beam waist indicated that the ring damage may not directly be induced by the laser pulse. The relationship between the filament length and the concentric ring depth showed that a longer filament corresponded to a clearer and deeper ring structure. A theoretical model was presented to describe the dynamic evolution of the concentric ring on the front surface of fused silica. The evolution of laser induced damage for fused silica has been disclosed, which can contribute to comprehend the underlying mechanism of laser-induced damage for transparent optical materials.

Despite the exceptional fire-suppressant capabilities of ultrafine dry powder fire extinguishing agents, additional work is essential to improve their overall fire-extinguishing performance. In this investigation, we explored the utility of Fe3+ loaded ZSM-5 zeolite in enhancing the firefighting capabilities of ultrafine dry powder fire extinguishing agents. The loading of transition ions Fe3+ onto the ZSM-5 zeolite was achieved through the ion solution exchange method. Interestingly, the loading of Fe element on Fe/ZSM-5 zeolite displayed a pattern of initial increase followed by decrease as the ion exchange time lengthened. Furthermore, the loading of Fe element on Fe/ZSM-5 zeolite was found to be influenced positively by the initial concentration of Fe3+ and pH levels. Impressively, under specific working conditions, the prepared Fe/ZSM-5 zeolite demonstrated a substantial Fe element loading of 5.82 %. Incorporation of ZSM-5 zeolite resulted in a 10.01 % enhancement in the fire-extinguishing efficiency of the ultrafine dry powder compared to undoped samples. Moreover, the incorporation of Fe/ZSM-5 zeolite has resulted in an enhancement of fire extinguishing efficiency by 20.45 % (S3), 24.20 % (S4), and 29.04 % (S5) in comparison to S1. These findings contribute to the understanding that the incorporation of Fe/ZSM-5 zeolite significantly enhances the fire extinguishing performance of ultrafine dry powder fire extinguishing agents, with extinguishing efficiency improving with increased Fe element loading.

As industrialization continues to deepen, polymers have become ubiquitous in daily life. However, their flammable characteristics pose significant safety risks. Therefore, supporting the global goal of sustainable development necessitates the development of high-performance, environmentally friendly flame retardants. Biomass phytic acid (PA) has emerged as a promising option because of its high phosphorus content and excellent biocompatibility. However, its combustion behaviors and chemical kinetic mechanisms remain unclear. In this study, quantum chemical calculation methods were used to construct a detailed PA chemical reaction kinetic model. A series of experiments were conducted to validate the model and evaluate PA's flame suppression effect. Utilizing a counterflow flame burner and particle image velocimetry (PIV), the inhibitory effect of various PA concentrations was examined based on the laminar flame speed of CH4/PA/Air mixture. The results revealed that a merely 0.2 % addition of PA could reduce the laminar flame speed by 38.9 %, demonstrating its significant flame suppression effect. Building on the foundational GRI-Mech 3.0 and integrating PA's pyrolysis and reaction mechanism, this study developed for the first time a detailed chemical model of CH4/PA/Air combustion. This model integrated PA's thermal decomposition module and thermodynamic data via ab-initio quantum chemical calculations, thereby accurately predicting global kinetic indicators such as laminar flame speed. Results suggested that the key reactions, such as PO2+H + M-*HOPO + M, HOPO2+H-*PO2+H2O, and HOPO + OH-*PO2+H2O primarily influenced the laminar flame speed. Moreover, the CFD simulation elucidated the complex interaction between PA and flame structures. A detailed analysis of the spatial distribution of key parameters such as temperature, combustion radicals, and effective inhibition radicals unveiled the PA's flame suppression mechanism in support of the practical application of this eco-friendly flame retardant.

To enhance the understanding of fire dynamics in building-integrated photovoltaic (BIPV) systems, an experimental study was performed to investigate the influence of pool fires generated by ignited PV panels on adjacent inclined unburned PV panels within an array. Experiments were conducted under 50 different conditions, encompassing a range of inclination angles (0 degrees to 90 degrees) and varying fire source heat release rates using a gas burner. The evolution of the flame morphology and characteristic behaviors influenced by nearby inclined surfaces was examined. The results indicate that asymmetrical air entrainment induced by the inclined surface causes the flame height to initially decrease and then increase with increasing inclination angle, while the flame tilt angle exhibits the opposite trend. Owing to the buoyancy components parallel and perpendicular to the inclined surface, the flame attachment length exhibits an increasing trend, while the distance from the flame tip to the inclined surface decreases monotonically with the inclination angle. The flame transitions from partial attachment to complete attachment mode within the range of 60 degrees to 70 degrees, which is a crucial factor influencing the morphology and behavior of the flame. Global correlations were established to describe the flame morphology through the force analysis of the flame. As the inclination angle increases, the flame transitions from non- attachment to intermittent attachment to the inclined surface, with the transition behavior quantified using the dimensionless heat release rate and trigonometric functions. Due to the restriction of the entrainment space, the flame pulsation frequency decreased with the increase of the inclination angle. Dimensionless models were formulated to predict the flame pulsation frequency, considering the hydraulic diameter for both free and wall flames. The morphology and characteristic behaviors of the flame predicted by the proposed model were compared with the measurement data, demonstrating reasonable agreement.

In this work, the possibility of enhancing the antioxidant capacity of whey protein (WP) through non-covalent interaction with methyl hesperidin (MH, a hesperidin derivative) was assessed. The underlying mechanism was analyzed in terms of multi-spectroscopy methods, thermodynamic analysis, and molecular docking simulation. The data indicated that MH could spontaneously bind to WP and form a non-fluorescent complex when physically mixed together. The presence of MH statically quenched the intrinsic fluorescence of WP, changed the microenvironment of amino acid residue, and altered the secondary and tertiary structure of WP, which in turn enhanced the antioxidant capacity of WP. The underlying mechanism may be assigned to hydrophobic interactions, which promoted MH inserting itself into the hydrophobic cavity in WP. The methoxy group on the B ring of MH may form hydrogen bonds with amino acids, which enhances the freedom of the phenyl hydroxyl group, resulting in higher antioxidant capacity than other hesperidin structural analogs. This research would enrich the theoretical basis about the interaction between protein and hesperidin-based derivatives, and it may supply valuable information for its application in the food and medicine fields.

Understanding the atmosphere-fire interaction is of vital importance for the fire management and fire-induced synoptic flow prediction. This work aims to reveal the mechanism of fire dynamics and its interaction with atmospheric boundary layer by considering the complex dual-fires condition that is rarely studied. Thus, the numerical simulations were performed with a detailed analysis of flame geometry, fingering structure, turbulence spectrum, Richardson (Ri) number. The results show that the flame morphological parameters changed significantly as increasing Nc number with the flame drag length reduced from 6.2 to 2.5 m and the flame inclination angle increased from 13.9° to 36.6°, especially an opposite trend of change was observed at buoyancy-driven regime when the dual-fire was considered. A lognormal distribution was indicated for fingering structure spacing, where the average spacing is between 1.4–0.9 m, which was apparently affected by dual-fires when Nc number is high. The profile of Ri also demonstrated the enhanced natural convection and the resulting forces imposed on the upstream flame for dual-fire cases, for which different fire-wind interaction mechanisms can be drawn at different magnitudes. The proper orthogonal decomposition analysis was developed to further reveal that the coherent structures in dual-fires condition were a strong perturbation of the downstream fire induced by the fire-fire interaction.

In this research, chlorogenic acid (CA) and corbicula fluminea protein hydrolysates (CFP) were physically mixed to simulate practical scenarios. The non-covalent complexes were detected in the system. The underlying mechanisms as well as their effects on the antioxidant properties and bioaccessibility of CFP were detailed investigated. For better comparison, CA covalent with CFP complexes were also fabricated. Overall, CA-CFP predominantly formed loose structural complexes through non-covalent interactions, whereas covalent interactions resulted in more compact conjunctions. The antioxidant activity of CFP was significantly enhanced following interaction with CA, whether through non-covalent or covalent means. Notably, the non-covalent complexes exhibited superior antioxidant capacity and demonstrated synergistic antioxidant effects. Furthermore, the incorporation of CA into CFP improved the bioaccessibility and gastrointestinal digestive antioxidant activity of CFP, with the beneficial effects being more pronounced in the non-covalent complexes. The bounded CA may be responsible for these changes through partially inhibiting the hydrolysis of CFP.

The four major Chinese carps are highly popular for their distinctive nutritional benefits. However, the differences in flavor among these carps remain unclear. This study investigated the flavor profiles of these carps using headspace solid-phase micro-extraction gas chromatography-mass spectrometry (HS-SPME-GC/MS) combined with ultra-fasted gas chromatography electronic nose (GC E-nose). The four major Chinese carps had high protein content (16.68-18.61 %) and low fat levels (0.42-1.29 %). A total of 45 volatile compounds were identified in these carps. Both the GC E-nose and HS-SPME-GC-MS results consistently showed significant flavor profiles differences among these carps, with Ctenopharyngodon Idella (CI) exhibiting the most pronounced distinctions compared to the other three species. Based on VIP >1 and p < 0.05, 10 key compounds including 2-Nonanone, Cyclodecanol, Eugenol, 1,3-Cyclooctadiene, etc., largely contributed to the distinctive overall flavor profile of four major Chinese carps derived mainly from amino acid and fatty acid metabolism.

Abstract The self-ignition accident of pressurized hydrogen leakage is regarded as one of the big potential risks in its wide utilization. In this work, a detailed investigation into the suppression effect of water mist on the hydrogen self-ignition and flame propagation is performed. A parametric study of the effect of water concentration and droplet size on flame dynamic is conducted. The results show that the fine water mist effectively reduces the shock-heating temperature, significantly prolonging the ignition time and distance. The water droplets have a direct contact with the fast growing flame, which leads to more intense two-phase interaction that results in the decoupling of shock wave from the leading flame and a more pronounced bimodal flame structures. The droplet size is found to have small effect when the water concentration is low, and the mist with a medium size of 50 μm shows a better inhibitory performance.

This work presents a numerical study of bi-component n-heptane/ethanol spray flames in a counterflow to improve the understanding of the effect of non-ideal mixtures on the flame-spray interaction. The simulations of this spray configuration allow for the detailed examination of the real fluid behavior and its influence on gas-phase combustion kinetics for a wide range of relevant parameters, i.e., droplet composition, size, and gas strain rate. The results reveal that due to the large real activity coefficient of n-heptane and the resulting selective evaporation of the heavier component, the burning characteristics of the spray with a high initial ethanol content do not differ if non-ideal mixture is considered. Conversely, the flame structure with a low ethanol content is substantially different, and displacement of the flame towards the spray side of the configuration is found. A multiple reaction zone, displaying both partially-premixed and diffusion flames, exists, which is overestimated spatially if the fluid is assumed ideal. In general, the ideal prediction of real fluid would misinterpret the composition evaporation order, prolonging the droplet lifetime and consequently, enhancing the flame-spray interaction locally, which results in a lower flame temperature. A parameter characterizing the multicomponent droplet penetration is introduced, which highlights the appreciable non-ideal effects that vary with droplet size and composition, and most importantly, further demonstrates the necessity of considering the real fluid properties in design of next-generation engines with blended fuels.

Sodium bicarbonate-based ultrafine dry powder fire extinguishing agents (UDEAs) exhibit high hygroscopicity and a tendency to agglomerate, which result in poor flowability and diminished extinguishing efficiency, thus proving to be crucial concerns in the UDEA design. The integration of hydrophobic nano silica (HNS) has been recognized as an effective strategy to tackle these challenges, but the precise optimal quantity of HNS in UDEA has been a subject of confusion. Consequently, the impact of HNS as an additive on the flowability of sodium bicarbonate UDEA was thoroughly examined. Through high-speed stirring, the surface of UDEA was evenly coated with HNS particles, resulting in a notable increase in the contact angle of the modified extinguishing agent to approximately 135.4°. Notably, the UDEA formulation with an 8% HNS addition exhibited the least cohesion, the highest flow function value, and the lowest spray resistance. Moreover, the study unveiled the underlying flow mechanism of sodium bicarbonate UDEA influenced by the HNS additive. The findings indicated that the most effective incorporation of HNS into sodium bicarbonate UDEA was 8%, considering both its hydrophobic properties and flow characteristics.

To unravel the interaction mechanism between droplets that is relevant for practical liquid fueled burners, the flame propagation characteristics of multi-droplet of emulsified diesel and biodiesel (FAME) fuels were studied using a suspended line droplet array. It was found that when S/d(0) <= 3 (ratio of droplet spacing to initial droplet diameter), the double droplets were ignited simultaneously and surrounded by a single flame, and as the droplet spacing increased, two independent flames were formed around each droplet. The highest flame propagation rate was attained at S/d(0) = 3, which was attributed to the consistent values of flame standoff ratio limited by the dominant heat conduction and finite evaporating rate. The droplet interaction, such as oxygen competition effect, enhanced with smaller droplet distance, can result in the reduction in the droplet combustion rate and flame propagation rate; the latter one, however, showed an increasing trend when small droplet or the size non-uniformity of droplet cloud was considered. In addition, the child droplet ejected from the emulsified droplets showed three burning modes and was an important factor promoting the flame spread, and the results showed that compared with the FAME emulsified fuels, the child droplets in diesel cases were more prone to ignition, expanding the burning regime.

Ethyl methyl carbonate (EMC) gained great attention because of its advantages shown in practical applications both as a blend with conventional oil-derived liquid fuels, and as a solvent being used in Li-ion cell electrolyte compositions. Thus, a better knowledge of the combustion characteristics of EMC/air premixed flames is necessary, which has not yet been well-explored. Towards this goal, the laminar flame propagation of EMC/air mixture was investigated using a constant-volume combustion chamber at the initial pressures of 1, 2, 5 and 8 atm, with the unburned temperature of 423 K and the equivalence ratios ranging from 0.7 to 1.5. A recently established chemical kinetic mechanism of EMC by Takahashi et al. (Combust. Flame 2022) was adopted for the theoretical prediction, which accurately reproduced the measured LBVs at 1-5 atm; however, it underpredicted the LBVs for the lean flame condition at 8 atm. According to the flame instability analysis, the increase in pressure leads to the elevated hydrodynamic instability and the decreased critical radius of spherical premixed flame. Meanwhile, the rich flames of EMC/air had the smaller critical Peclet numbers and suffered the more severe thermal-diffusive instabilities.

Pool fires are one of the most commonly encountered flame types in fire disasters, and the accurate and detailed modeling of pool fires is beneficial for the hazard analysis and assessment of liquid-related fire accidents. The radiation model is known to be the critical component in the accurate simulation of various fire scenarios. Therefore, to develop a proper radiation model, an LES study of a large-scale methanol pool fire was performed in this work by coupling four different radiation models into the open-source fire simulation code FDS and solving the radiation intensity transport equation using the discrete ordinates method. The impact characteristics of different radiation models are evaluated in detail with the NIST experiments, where the comparative analysis was carried out. Regarding the temperature calculations, the WSGG (weighted-sum-of-gray-gases)-based radiation model and Cassol’s model performed better. In addition, all models predict pulsation frequencies well. However, regarding the prediction of the radiative heat fluxes, Cassol’s two models and the FDS default model outperformed the other models, which indicates that the database for obtaining the spectral information of each species and the method to determine the WSGG coefficient of mixed gases are significant factors for the successful prediction of flame radiation.