Sewage sludge poses a major challenge for resource utilization and thermal disposal because of its high moisture content, low calorific value, and the slagging and corrosion risks associated with alkali and alkaline earth metals (AAEMs). Synergistic incineration with organic-rich fermentation residue offers a potential route for improving sludge thermal treatment; however, the particle-scale evolution and in-flame transformation behavior of AAEMs during this process remain insufficiently understood. In this study, the synergistic incineration of sludge and fermentation residue was investigated using phase-selective laser-induced breakdown spectroscopy (PS-LIBS) and OH planar laser-induced fluorescence (OH-PLIF), combined with offline X-ray diffraction and fluorescence measurements. PS-LIBS was used to track the relative spatial evolution of particle-phase Na, K, Ca, and Al, while OH-PLIF provided information on flame structure and reaction-zone distribution. The results suggest a possible particle-evolution pathway involving volatile release, fragmentation, alkali vaporization, downstream re-capture, and agglomeration, ultimately leading to the formation of composite inorganic phases. The roles of AAEMs, S, and Cl were further discussed to interpret alkali redistribution and particle-phase signal evolution. Finally, the NOx emissions during the co-combustion of sludge and fermentation residues are examined which showed a certain degree of reduction. These findings provide particle-scale insight into AAEM transformation during sludge–fermentation residue synergistic incineration and offer a useful reference for clean thermal treatment of heterogeneous organic wastes.

This study investigates the effects of nanoparticle seeding on flame stabilization and flame front structure in premixed Methane and Methane-Hydrogen flames using a low-swirl burner. Acetylene black nanoparticles are introduced at 0.01 mg/s across 36 test conditions, spanning three fuel blends and five equivalence ratios (Phi = 0.6-1.1). High-speed color imaging and Hydroxyl Radical Planar Laser-Induced Fluorescence (OH-PLIF) diagnostics capture flame dynamics, while custom MATLAB processing quantifies curvature and flame surface density. Seeding consistently narrows the curvature probability density function (PDF), reduces curvature variance (up to 31 %), and increases PDF peaks (up to 34.6 %), consistent with reduced geometric wrinkling and a more coherent flame surface. While Hydrogen addition extends lean flammability, its combination with seeding provides additional but diminishing stabilization. Flame brush comparisons confirm that seeding promotes smoother, spatially uniform flame structures without altering global geometry. These findings support nanoparticle seeding as a passive strategy for improving flame stability in lean-premixed combustion systems.

A novel composite phase change material (CPCM) which combines sodium sulfate decahydrate/sodium acetate trihydrate eutectic hydrated salt (EHS) and eicosane was prepared using the inverse emulsion template method. Step-cooling characteristic tests revealed that the addition of 1.5 wt % borax significantly reduced the supercooling degree of the PCM from 6.92 to 2.54 degrees C. Thermal storage performance analysis indicated that when the expanded graphite was 1 and 3 wt %, the latent heat values during heat storage and release were 133.7 and 114.5 J/g and 127.9 and 106.9 J/g, respectively. Furthermore, after subjecting the material to 100 heating/cooling cycles, the latent heat of the phase change experienced only a minimal decrease of 2.7%, indicating excellent thermal storage stability. The CPCM also demonstrated superior performance on thermal regulation and flame retardancy tests. Given these characteristics, the proposed CPCM suggests robust thermal storage performance and has potential applications for battery thermal management systems.

The evolution and governing factors of particle agglomeration dominated by van der Waals force in freely evolving gas-solid suspensions are numerically investigated by employing lattice Boltzmann method (LBM) coupled with discrete element method (DEM). Three steady-state agglomeration behaviors are identified, including complete agglomeration, partial agglomeration and no agglomeration. It is discovered that the initial granular temperature only affects the evolution process instead of final agglomeration state. Furthermore, a critical granular temperature to identify the onset of agglomeration is associated with the critical velocity of adhesive particles. An agglomeration phase diagram is thus deduced, where the transition boundary is well described by the dimensionless Bond number, adhesion number, as well as an a priori agglomeration number. More importantly, the dimensionless description can be extended to address the Geldart Group A and B particles, which provide a new theoretical perspective on particle agglomeration in gas-solid suspensions and its connection to Geldart classification.

Using paraffin as phase change material (PCM), the melting process of gradient foamed metal composite PCM was numerically simulated. Ten kinds of gradient foamed metal with average porosity of 86 % and average pore density of 10 PPI (1 PPI = one pore per inch) were designed by using a three-dimensional structure model of sixsided through circular hole. The impact of the pore density and porosity of the foamed metal with different gradient parent materials on the heat transfer and heat storage performance of the composite PCM was systematically studied. The results reveal that the heat transfer process of the composite PCM containing gradient foamed metal is mainly affected by heat conduction. The main thermal resistance is located at the bottom layer, and the heat transfer performance could be enhanced by rationally designing the parent material gradient. And even if the entire bottom layer is foamed metal Cu, the main thermal resistance of the composite PCM is still located in the bottom layer. Through a reasonable porosity gradient design, the melting rate could be further accelerated. Compared with the composite PCM containing uniform porosity gradient foam Cu, the complete melting time of the porosity gradient of 0.90-0.86-0.82 can be shortened by 11.30 %. Thermal non-equilibrium phenomenon exists in the composite PCM containing gradient foamed metal. As the pore density of foamed metal located at bottom layer increases, the maximum average temperature difference decreases. A reasonable design of the pore density gradient can better weaken the thermal non-equilibrium phenomenon. Furthermore, the heat storage density per unit mass of the composite PCM containing gradient foamed metal increases with the increase of the average porosity. Compared with the composite PCM containing gradient foamed metal with Ni-Al-Cu parent material, the heat storage density per unit mass is higher in the stable stage and increases more rapidly during the heat storage process in the composite PCM containing uniform gradient foam Al.

As global energy demands rise, the need for advanced combustion technologies that support sustainable fuels while minimizing emissions has become increasingly critical. This study explores the influence of nanoparticle seeding on flame stability and blowoff limits in a Low Swirl Burner (LSB). Acetylene black nanoparticles were introduced at a controlled seeding rate into pure Methane, Methane-hydrogen blends. To achieve precise and uniform particle injection, a custom-built seeder was employed, consisting of a rotating arm to prevent particle agglomeration and a vibrator operating to ensure a steady flow through a narrow nozzle. To analyze the impact of nanoparticle seeding, high-speed videography and Hydroxyl Radical Planar Laser-Induced Fluorescence (OH-PLIF) imaging were utilized to capture flame dynamics, track the flame front, and quantify radius of curvature of the local flame surface. The blowoff results show that nanoparticle seeding improves blowoff limit by 6.67% for pure Methane. While seeding provides additional benefits for the 20% hydrogen blend (increasing blowoff improvement from 20% to 21.7%), it shows no measurable effect on the 40% hydrogen blend's blowoff limit. The study reveals that trace acetylene black seeding (0.01 mg/s) significantly stabilizes methane flames, evidenced by a 19.6% higher curvature PDF peak at Equivalence ratio, phi =1 and smoother flame brush morphology, indicating reduced wrinkling. Seeding's stabilizing effect is most pronounced in rich/stoichiometric conditions (PDF peaks increase by 16.734.6% for F=0.8-1.1) but diminishes in lean flames. Hydrogen blending (20-40% H2) broadens curvature distributions, confirming inherent instability from enhanced diffusivity/reactivity. Both averaged OH-PLIF fronts and flame brush images corroborate that seeding promotes spatially uniform combustion by damping small- scale turbulence without altering bulk flame structure. The insights gained from this study contribute to the development of cleaner and more efficient combustion strategies for sustainable fuel applications.

Surface-disordered TiO2 nanoparticles exhibiting various colors including grey, yellow, blue, and black have attracted considerable attention owing to their outstanding photocatalytic activity, attributed to their narrow bandgap and thus enhanced absorption of solar energy. In this study, we have successfully synthesized TiO2 nanoparticles with tailored surface-disorder structures using a well-controlled H2/O2/N2 premixed Bunsen flame supported by multi-element diffusion flames in a single step. To systematically examine the influence of gas composition on surface-disorder layer formation, we designed four distinct flame conditions maintaining consistent flame structures, adiabatic temperatures, and precursor concentrations while varying the atmospheric composition. In-situ OH-planar laser induced fluorescence (PLIF), spontaneous Raman scattering (SRS), and 2D phase-selective laser-induced breakdown spectroscopy (PS-LIBS) has been employed to characterize the flame structures, temperature profiles, atmospheric conditions, and particle volume fraction across all flame conditions. The in-situ diagnostic results verify that the designed flame conditions have identical particle formation and growth route in flames but with varying gas-particle interactions under different post-flame atmospheres. Ex-situ characterization through high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) of the synthesized nanoparticles demonstrates that TiO2 nanoparticles with surface disorder structure and rutile phase are more preferentially formed under reducing atmospheric condition. Furthermore, both ex-situ UV-Vis spectra and in-situ PS-LIBS indicated that a higher H2 mole fraction in the post-flame region can enhance the light absorption of the synthesized nanoparticles attributed their stronger surface disorder structures.

High-temperature thermal energy storage shows promise for advancing industrial decarbonization. Within this field, earth-based particulates can be attractive for widespread adoption due to their scalability and abundant resource availability.

The melting of paraffin‑aluminum composite PCM with stochastic open-cell metal foam digitally synthesized with a novel numerical approach is investigated via an enthalpy-based double population lattice Boltzmann method. The influences of the geometry of the metal foams, including the volume fraction, the average pore size, the pore size distribution as well as the pore shape, on the melting performance are well discussed and analyzed. The results demonstrate that the presence of highly conductive metal foam promotes the melting rate only when its volume fraction exceeds a certain threshold. Furthermore, increasing the average pore size or widening the pose size distribution when the volume fraction is fixed is not beneficial to the acceleration of melting. Besides, the pore shapes are proved to have little effect on the overall melting performance. Therefore, it is concluded that the optimized design strategy of such composite PCM with highly conducive metal foams is to utilize small and uniform pore sizes.

Bubble column offers various advantages compared to other devices in the chemical process industry, which was used as a fine particulate and sulfuric acid mist control device. Bubble formation behaviors, including volume, diameter and velocity, were systematically investigated in the single submerged micro-capillary test bed under constant flow conditions by using the high-speed optical camera in this paper. Besides, force model of the bubble forming process was established based on the experimental results. It was found that the formed bubble turned to be elliptical and bubble shape was independent of the gas flow rate under the conditions of this study. In addition, bubble velocity was found quickly reached the highest level, then decreased, and eventually tended to be stable (0.02-0.1 m/s). By analyzing the bubble forces, it was found that pressure force FP, surface tension force FS and buoyancy force FB played different roles in different bubble formation process. These results can provide detailed parameters for the modeling of bubble formation process under the test conditions.

为降低舱外航天服头部空间噪声水平,以保障通话效果和航天员听力,进行舱外航天服头部空间主动降噪技术研究.根据多入多出技术构建声场主动降噪模型,求解空间三维声全息函数,实现头部空间的噪声声场建模.考虑到实际部署的环境限制,设计基于部署约束的主动降噪算法,在空间场主动降噪系统中通过全局控制,完成空间场的主动降噪.经过实际场景的测试,提出的主动降噪算法在人耳处降噪效果为13.88 dB,有效降噪频率范围为450～2000 Hz,可有效降低低频段噪声.

High-performance thermal energy storage technology based on phase change material (PCM) plays an important role in reducing the building energy consumption and realizing efficient energy utilization. However, the drawbacks such as liquid phase leakage, poor thermal conductivity, and low cycle stability, significantly reduces its service life and limits its further application. In this paper, a new microencapsulated phase change material (MPCM) containing graphite-SiO2 shell and eicosane-octadecane (E-O) core was prepared by the sol-gel method. A high thermal conductivity shell was successfully constructed inside the MPCM by double-layer encapsulation technology to accommodate the poor thermal conductivity of E-O. The prepared MPCM had perfect core-shell structures and spherical morphologies, with great enhancement in the thermal conductivity. When the mass ratio of E-O/SiO2 is 2:1, the encapsulation ratio reaches 71.2%, and the corresponding phase change enthalpy of the MPCM is 133.2 kJ/kg, which remains almost constant even after 2000 heating-cooling cycles. The MPCM is further added to phosphogypsum (PG) which is a by-product of the wet-process production of phosphoric acid, to form composite MPCM. The compressive strength of the composite material is still as high as 5.8 MPa with 15% MPCM despite the negative effect on strength by MPCM. The PG-MPCM showed a good thermal storage capacity and compatibility, furthermore, the thermal stability was maintained also after 2000 thermal cycles. Therefore, the composite PG-MPCM developed in this work is capable of energy storage to reduce the building energy consumption and provides great potential in the PG resource utilization for enhanced environmental protection.

In this paper, a detailed study of two specific frequency-selecting procedures for all-fiber single-frequency lasers is presented. The frequency-selection has been realized by using a multi-ring cavity (MRC) and double Mach-Zehnder interferometer (MZI), respectively. Firstly, the frequency-selecting principles of two procedures have been simply summarized, and the influences of the sub-ring lengths in the MRC, the optical path difference between two arms of a MZI, and the length of the primary ring cavity on single-frequency lasers have been analysed in detail. Then, the 1064.3 nm single-frequency emission with the linewidth <10 kHz in the same Ytterbium-doped fiber laser scheme has been achieved by employing two different procedures. Finally, the pump power thresholds of the MRC-based and MZI-based single-frequency fiber lasers were measured as 60 and 70 mW, the slope efficiencies were measured as 6.5 and 5.3%, and the side-mode suppression ratios were measured as 45 and 48 dB, respectively. The results reveal that the MRC-based single frequency fiber lasers have the higher energy efficiency while the MZI-based ones have the better mode stability.

In this paper, a simple and effective method is proposed for measuring the focal length of a weak negative thermallyinduced lens. Generally, it is very difficult to measure the focal length larger than 1000 mm of a weak thermally-induced lens by utilizing the traditional procedures. In our experiment, we planned to construct a Yb:KGW laser system almost without the thermally-induced lens in which the focal length of the laser crystal should be measured precisely. With respect to the optical features of Yb:KGW crystal, the thermally-induced characteristics look like something of a negative lens with weak effects. The steps of measuring the focal length of a thermally-induced lens of the laser medium have been adopted as follows. First, the relationship between the focal length f1 of a positive assistant lens as well as the position of the assistant lens and the focal length fT of a thermally-induced lens were carefully analyzed and the experimental setup were designed through the theoretical simulation. Secondly, the variation of the spot size and post position for a He-Ne probe laser have been experimentally investigated after the probe laser beam passed through a thermally-induced lens (fT) and an assistant lens (f1) with the different drive currents of a pump LD with the wavelength of 980 nm. Then, the post position for a He-Ne laser beam can be obtained by use of a least square method, and then the focal length of a weak thermally-induced lens can be deduced with an indirect detection method. In this paper, we introduce a new technique for the measurement of the focal length with the absolute value large than 1000 mm of a negative lens, which has not been reported until now. The results might be useful for the evaluation of a weak thermally-induced lens of almost all solid-state lasers (SSLs).

This paper aims to report the evolution characteristics of the coarse ash particles generated from the co-incineration of municipal solid waste with other wastes, e.g. sewage sludge, to suggest suitable operational strategies to handle the side effects. By using an evolution model which addresses the mechanism of char combustion, volatile-induced fragmentation, and the transformation of included and excluded minerals particles, the coarse ash particle evolution process in the waste incinerator is successfully predicted. By comparing with in-situ measurement data of a 200t/d forward grate MSW incinerator, the predicted total particle concentration is 275.7 mg/Nm3, and the relative difference is about 4.2%. Although the variation in flue gas parameters has little effect on the distribution characteristics of coarse ash particles from MSWI, the carbon content of coarse ash particles is more sensitive to flue parameter change. Due to the tight relationship between the PCDD/Fs and the carbon content of ash particles under the mechanism of the de novo process, the increase in carbon concentration caused by the co-incineration of low-calorific value waste will increase the probability of the dioxins formation.

Development of thermal storage material from recycled solid waste resources can further enhance the economic and environmental benefits of thermal energy storage system. Thermal properties of steel slag as sensible heat storage material are examined and further enhanced by Na2CO3 activation. The steel slag remains stable until 1200 degrees C in TG-DSC test, and the morphology kept unchanged after 200 thermal cycles (400-900 degrees C), indicating good thermal cyclic stability. The thermal energy storage density of steel slag is 797.9 kJ.kg(-1) (400-900 degrees C), the thermal conductivity was measured as 0.505, 0.532 and 0.670 W.(m.K)(-1) at 25, 250 and 500 degrees C, respectively. When the steel slag is further modified by Na2CO3, the morphology and phase of the material remained stable, and the DSC curve trend unchanged after thermal cycle. The thermal energy storage density reaches 997.0 kJ.kg(-1) (400-900 degrees C), which is 25.3% higher than original steel slag. Even more, the thermal conductivity is 1.331, 1.323, 0.889 W.(m.K)(-1) at 25, 250, and 500 degrees C, respectively, which is 32.7% higher than that of steel slag. Hence, the thermal properties of steel slag have been significantly improved by the developed Na2CO3 activation process.

碳酸盐(Na2CO3和K2CO3)是极具潜力的高温相变材料,高炉矿渣(blast furnace slag,BS)作为基体材料兼具环境和经济效益,但是碳酸盐在高温熔融状态下通常会与高炉矿渣发生反应.为此,本工作发展两步法制备路线以攻克这一问题.首先,使用碳酸盐对高炉矿渣进行改性,得到化学性质稳定的改性矿渣(modified blast furnace slag,MBS);其次,通过混合烧结法制备碳酸盐/改性矿渣定型复合相变材料(form-stable phase change materials,FSPCMs).经过冷热循环测试制备的K2CO3/KMBS复合相变材料比Na2CO3/NMBS的定型效果更优.分析发现,K2CO3与KMBS具有良好的化学相容性,随着K2CO3含量增加,K2CO3/KMBS定型相变材料的潜热逐渐增加,且测试结果与计算一致,在质量比4:6(40K2CO3/60KMBS)时,潜热为94.8 kJ/kg,且热稳定性最好.

Because of its intrinsic topological charges (TCs), a vortex beam offers a Hilbert space with a higher dimension when it is utilized as a carrier of space optical communication. As a result , optical communication based on vortex beams enjoys significantly improved channel capacity and security. At the channel receiver in optical communication, TCs need to he identified accurately and rapidly to decode the transmitted information. In this paper, the dimension of polarization state is introduced into the process of TC identification, and the influence of polarization state on TC identification is studied from the perspectives of numerical simulation and experimental verification. Interference images of a signal beam and a reference beam with different polarization states in a Mach-Zehnder interferometer are analyzed. The results show that the Gaussian beam (reference beam) with the circular polarization state is the most favorable choice for identifying the TCs of the vortex beam (signal beam) with the same polarization state, and these signal beam and reference beam also appear to be least sensitive to the angle of the interference optical path during TC identification. The theoretical simulation is in good agreement with the experimental data which indicates that the proposed polarization interference-based TC identification scheme provides a reference for future high speed and high capacity optical communication based on vortex beams over distances in the order of magnitude of several kilometers.

In this work, an optical emission-based two-color method was experimentally investigated for the measurement of surface temperatures of different types of fly ash samples using a CCD camera. A heating system consisting of a Hencken flat-flame burner, a narrow piece of stainless steel wire mesh to separate the flame and the ash samples to be studied, and a thermocouple to record the temperature, was used to heat fly ash samples. A color camera equipped with a tri-band filter was used to capture radiation images. Fly ash samples collected from three kinds of coal-fired boilers were heated and imaged at different temperatures. The chemical compositions, elements, and particle size distributions were analyzed. The emissivity ratios of the wavelengths corresponding to the R and G optical channels and permitted by the tri-band filter were experimentally determined. A two-color method was subsequently used to calculate the average surface temperatures with relative errors within ±2% in the experiments, and an uncertainty analysis was conducted. Surface temperature distributions were also calculated and presented. The results demonstrate that the emission-based two-color method can be used to determine reliable average surface temperatures and surface temperature distributions when the radiation emitted from the ash samples is obviously greater than the ambient light. The results also show that the method has a lower limit of temperature measurement, which will lessen with the use of larger apertures and a higher radiation capacity of the ash samples to be studied.