Table of Content

28 December 2025, Volume 25 Issue 12

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Cover and Contents

The Chinese Journal of Process Engineering. 2025, 25(12):  0. 

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Research Paper

Study on flow and heat transfer characteristics in indirect electric heating furnace for molten salt

Yongcang REN Nan LIU Fengzhi SUN Chunhua JIA Xinyong GUO Chunjian HUANG Weidong ZHAO Guanda WANG Rui ZHANG Juan WANG

The Chinese Journal of Process Engineering. 2025, 25(12):  1227-1237.  DOI: 10.12034/j.issn.1009-606X.225066

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In order to meet the needs of green environmental protection for energy conservation and emission reduction, and make full use of the advantages of good heat resistance and stability of molten salt, an electric heating furnace with indirect heating of molten salt was developed. Based on the natural convection model and Boussinesq hypothesis, the flow and heat transfer characteristics of molten salt and heat transfer oil in the enclosed space of the indirect heating furnace were studied by numerical simulation method, and the effects of different surface thermal strengths on the flow and heat transfer characteristics of the indirect electric heating furnace were compared. The results show that the density difference and temperature difference caused by the expansion of molten salt in the furnace after heating form a natural convection heat transfer in a confined space, and the average flow velocity of molten salt is 0.00613m/s when the surface thermal strength is 100%. The average temperature is 409.3°C, and a symmetrical annular circulation flow is formed on the cross-section of the electric heating tube from the bottom of the high-temperature heating tube to the upper heat transfer oil pipe, which strengthens the natural convection and heat transfer effect in the furnace, and the overall flow field and temperature distribution in the furnace are stable and uniform, and the heat released by the electric heating tube increases the inlet and outlet temperature of the heat transfer oil by 13.1°C through the indirect heating of molten salt of the intermediate medium, which can meet the process requirements. When the thermal intensity exceeds 100%, the natural convection circulation of molten salt in the furnace is significantly enhanced, the turbulence degree increases, and there is an obvious velocity boundary between the molten salt above the electric heating tube and the surrounding area, which positively affects the flow and heat transfer characteristics in the furnace.

Optimization simulation of operating conditions of four-channel pulverized coal burner in cement rotary kiln

Lanxin WANG Jing GUAN Yujie TIAN Yinjie LIU Fei LI Jiayuan YE Chengwen XU Jun SHEN Chunxi LU Wei WANG

The Chinese Journal of Process Engineering. 2025, 25(12):  1238-1247.  DOI: 10.12034/j.issn.1009-606X.225075

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As the core equipment of cement firing system, the performance of cement rotary kiln burner has an important impact on cement production efficiency and quality. However, due to the difficulty of comprehensively measuring the high-temperature and complex reaction process in the rotary kiln, the evaluation of burner performance often relies on experience and lacks theoretical guidance. To this end, computational fluid dynamics (CFD) is used to simulate the combustion process of pulverized coal to optimize the burner of cement rotary kiln. The optimization simulation results show that with the increase of axial wind velocity within a reasonable range, the gas phase temperature increases significantly, the high temperature region expands, the oxygen consumption rate increases, the mass fraction of carbon monoxide decreases, and the combustion efficiency is improved. The increase of swirl flow wind velocity has little effect on the temperature field, but it can significantly improve the mixing effect of pulverized coal and air and promote combustion. On this basis, the performance of the burner is optimized by increasing the axial flow wind velocity and swirl flow wind velocity, which improves the temperature field and component field distribution in the kiln, and affects the clinker mineral composition, in which the content of C3S and C4AF increase, and the content of C2S and C3A decrease, which has a positive impact on the performance of cement. In conclusion, the effects of axial flow wind velocity and swirl flow wind velocity on the performance of cement rotary kiln burner are deeply analyzed by numerical simulation method, which provides theoretical support for the optimal design of the burner, and the proposed burner optimization scheme effectively improves the distribution of temperature field and species field in the kiln, and improve the combustion efficiency and clinker quality of the fuel.

Analysis of liquid-liquid heterogeneous mixing characteristics in self-excited oscillating pulsed jet apparatus

Yalong CHENG Kunming ZHANG Meiqi ZHANG Xiaoju LU Yongchun HUANG Xiangyi TANG Linghui LIU

The Chinese Journal of Process Engineering. 2025, 25(12):  1248-1261.  DOI: 10.12034/j.issn.1009-606X.225094

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The self-excited oscillating pulsed jet apparatus has attracted considerable attention due to its simple structure, ability to generate passive oscillatory cavitation, and ease of engineering application. Nevertheless, the majority of extant studies on self-excited oscillating pulsed jets focus on homogeneous water-based media, while research on the flow and mixing characteristics of multiphase media remains relatively scarce. This limitation hinders its application in enhancing liquid-liquid heterogeneous phase mixing processes. To elucidate the mixing mechanism of oil-water heterogeneous media in the jet apparatus, this study employs oil as the continuous phase and water as the dispersed phase. Numerical simulations were conducted using the realizable k-ε turbulence model, Euler multiphase flow model, and population balance model (PBM), with simulation accuracy validated through experiments. Based on this, the mixing process of oil-water heterogeneous media inside the jet apparatus and the droplet size distribution characteristics of the dispersed phase were simulated and analyzed. The results indicated that oil-water heterogeneous media generated cavitation bubbles with size periodic variations and pulsating cavitation jets inside the jet apparatus. Under the synergistic action of turbulent inertial forces and viscous shear forces, dispersed-phase droplets were broken up, thereby promoting the mixing of the oil and water phases. Further analysis revealed significant differences in the primary regions where turbulent inertial forces and viscous shear forces acted within the jet apparatus. Turbulent inertial forces were mainly concentrated near the outlet and inlet of the resonator cavity, facilitating fluid mixing in this region, whereas viscous shear forces mainly produced near the collision wall of the resonator cavity and the lower nozzle channel wall, enhancing the mixing process in these areas. The combined effect of turbulent inertial forces and viscous shear forces led to the continuous breakup of dispersed-phase droplets, effectively intensifying the mixing process of oil-water heterogeneous media. In addition, mixing by jet apparatus can obtain narrowly-distributed dispersed-phase (water) droplets.

Study on impact of wettability on filtration performance of coalescing filter materials

Li ZHANG Qiling YIN Xuesong HUANG Ying LI Yihang DING Yuchen XIE Cheng CHANG

The Chinese Journal of Process Engineering. 2025, 25(12):  1262-1273.  DOI: 10.12034/j.issn.1009-606X.225078

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Impurities such as oil mist entrained during natural gas extraction and transportation can affect the reliable operation of equipment such as metering instruments and compressor units in the pipeline system. Using coalescing filters made from filter materials is currently a reliable method for removing oil mist and other impurities. Wettability has been proven to be an important factor affecting the oil mist filtration performance of filter materials, but its specific influencing mechanism remains unclear. This study systematically investigates the effect of wettability on the oil mist filtration performance of filter materials, aiming to address the issues of low filtration efficiency and high filtration resistance in oleophilic filter materials currently used in industry. The results indicate that filter materials with higher oleophobicity exhibit better oil mist filtration performance, manifested primarily as increased filtration efficiency and reduced steady-state pressure drop. Notably, for lower-precision filter materials, superoleophobic materials exhibit a 13.62% increase in filtration efficiency and a 20.46% decrease in steady-state pressure drop compared to oleophilic materials. In experiments with multi-layer filter materials combinations, the results reveal that filter materials with higher oleophobicity exhibit higher filtration efficiency and lower steady-state pressure drop. Combining these findings with the "jump-channel" model, the results suggest that filter materials with higher oleophobicity have lower channel pressure drop. The experimental results of this study provide a reliable theoretical basis for optimizing coalescing filter materials used in the natural gas pipeline transportation industry.

Study on the behavior of decoppered anode slime reduction smelting for the enrichment rare and precious metals

Yongqi MA Juan XU Fuyuan ZHANG Yongpan TIAN Yuxin HU Yangrui REN

The Chinese Journal of Process Engineering. 2025, 25(12):  1274-1284.  DOI: 10.12034/j.issn.1009-606X.225137

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The Kaldo furnace smelting technology is a typical process for the comprehensive treatment of copper anode slimes. However, the reduction sequence of key components and the phase evolution mechanisms remain unclear. In this study, simulations are conducted to analyze the slag system and reduction thermodynamics. The phase evolution during the reduction smelting of decoppered anode slimes for the collection of precious and rare metals is investigated through microscopic characterization of the slag and noble lead samples.The results indicate that the reduction smelting of decoppered anode slimes primarily forms a PbO-Na2O-SiO2 ternary slag system containing PbSiO3 and Na2Si2O5 phases. The reduction sequence of elements is determined as Ag>Se>Te>Bi>Pb. The main phase evolution pathway of PbSO4 follows the sequence PbSO4→PbO?PbSO4→PbS→Pb. The noble lead phases consist of PbSe, BiSe, and AgTe, with no diffraction peaks corresponding to elemental single phases observed. SEM analysis reveals that Pb and Se share similar distribution regions, while Ag and Bi exhibit complementary distribution patterns. Te is uniformly distributed, whereas Ag, Bi, and Pb show concentrated distribution zones with phenomena of segregation and contrast differences. XPS results show that Pb, Ag, Bi and Te in precious lead have zero valence and positive valence, and the proportion of 0 valence is 64%, 88%, 52%, and 47%, respectively. In contrast, Se exists in 38% zero-valence state and 62% negative valence state (Se2-). Due to the uneven distribution of metal particles, the unaggregated metal particles Pb, Bi and Se mainly form PbSe and BiSe intermetallic compounds, and Ag and Te form AgTe. Combined with XRD and SEM characterization, it is shown that the smelting reduction process of copper anode slime mainly forms stable intermetallic compounds to realize the capture of rare and precious metals.

Effect of foaming temperature on self-foaming polymethacryimide foam

Pengxuan ZHANG Huijuan BAI Chengcheng DING Yu QIAO Duo WANG Junbo XU Chao YANG

The Chinese Journal of Process Engineering. 2025, 25(12):  1285-1291.  DOI: 10.12034/j.issn.1009-606X.225064

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Polymethylacrylimide (PMI) foam is a kind of rigid foam with excellent thermodynamic properties, widely used in aerospace, sports equipment, and medical equipment. The foam properties of PMI foam are affected by the blowing agent. The type and amount of gas produced by the decomposition of blowing agent during heating have an effect on the size, morphology, and properties of PMI foam. The thermodynamic properties of self-foaming PMI foam using copolymerizable foaming monomers are directly affected by the foaming monomers. Therefore, in this work, acrylonitrile (AN) and methacrylic acid (MAA) were used as polymerization monomers, acrylamide (AM) as crosslinking agent, azodiisobutyronitrile (AIBN) as initiator, and tert-butyl methacrylate (tBMA) as copolymerizable foaming monomers. Lightweight and high strength PMI foam was prepared by free radical polymerization and free thermal foaming. The tert-butyl ester group in tBMA would thermally decompose into carboxyl groups and isobutene during the foaming stage, and the release rate of isobutene determined the physical structure of PMI and then affected its performance. Therefore, the effects of different foaming temperatures on the microstructure and thermodynamic properties of PMI foam were investigated. The physicochemical structure and properties of PMI foam were analyzed by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (SEM), thermogravimetric analyzer (TGA), differential scanning calorimeter (DSC), and universal testing machine. The results showed that with the increase of foaming temperature, the imimization degree of PMI increased, which improved the thermal stability of foam. At the same time, the high foaming temperature also increased the size of the bubble, resulting in a decrease in the density and mechanical properties of the foam. When foamed at 200℃, the foam had a low apparent density of 63 kg/m3, and exhibited excellent thermal stability and mechanical properties, with a glass transition temperature (Tg) of 216.1℃ and a compressive strength of 1.08 MPa.

In situ Raman spectroscopic monitoring of conversion of acrylamide-acrylic acid copolymerization

Jiaxian WEN Cheng CHANG Xueping GU Lianfang FENG Cailiang ZHANG

The Chinese Journal of Process Engineering. 2025, 25(12):  1292-1299.  DOI: 10.12034/j.issn.1009-606X.225088

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The aqueous copolymerization of acrylamide (AM) and acrylic acid (AA) is essential for synthesizing poly(AM-co-AA), an anionic polymer widely applied in enhanced oil recovery, mining, and wastewater treatment. However, rapid reaction kinetics, high viscosity, and sampling challenges hinder real-time monitoring of monomer conversion rates using conventional offline methods. This study proposes a non-destructive in situ Raman spectroscopic approach to track conversion rates dynamically. Characteristic Raman bands associated with structural changes during polymerization are identified: C-N stretching (1386~1517 cm-1) for AM consumption, C=C stretching (1517~1732 cm-1) for SA consumption, and CH2 bending (1363 cm-1) as an invariant reference for spectral normalization. Experiments were conducted under varied initiation temperatures (1~30℃) and composite initiator ratios (azo/redox initiators: 0∶100~90∶10). Real-time Raman spectra were processed to correct baseline drift and normalized using the CH2 bending peak. Key spectral regions were analyzed to quantify peak area changes, which were correlated with monomer consumption derived from offline NMR validation. A mechanistic model linking peak area changes to conversion rates was developed, with parameters regressed via multivariate least-squares fitting. The model demonstrated high accuracy, achieving average R2 values of 0.989 and 0.981 for predicting AM and SA conversions using 1386~1517 cm-1 and 1517~1732 cm-1 bands, respectively. Independent validation tests yielded an average relative error of 2.14%. This approach enables real-time, non-invasive monitoring of copolymerization kinetics, overcoming limitations of traditional destructive techniques. By integrating spectral analysis with mechanistic modeling, the method minimizes interference from overlapping peaks and environmental fluctuations. The results underscore Raman spectroscopy's potential for online quality control in industrial batch processes, ensuring consistent product performance through precise conversion rate tracking. The established framework provides a foundation for optimizing reaction conditions and enhancing production efficiency in polymer manufacturing.

Synthesis of lithium titanate nanotubes via anodic oxidation

Wen YANG Chaonan WU Juan XIE Yongpan TIAN Shiwei HE Zhuo ZHAO

The Chinese Journal of Process Engineering. 2025, 25(12):  1300-1307.  DOI: 10.12034/j.issn.1009-606X.225115

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As a critical component in lithium-ion battery technology, lithium has witnessed exponentially growing demand in renewable energy systems, driven by global decarbonization initiatives. Notably, lithium titanate, serving as an advanced lithium-ion sieve, demonstrates exceptional potential for selective lithium extraction from multicomponent brine systems containing competing cations such as Na+ and Mg2+, particularly due to its superior structural stability compared to manganese-based counterparts. In this study, hierarchically structured lithium titanate nanotube arrays with tunable surface porosity and enhanced interfacial adhesion were engineered via a multi-step synthesis protocol integrating anodic oxidation with lithiation annealing. Using titanium wire as the raw material and ethylene glycol as the electrolyte, TiO2 nanotube arrays were fabricated by controlling anodic oxidation voltage, fluoride ion concentration, and oxidation time. The lithium ion sieve was subsequently obtained through lithiation annealing and acid treatment. Experimental results demonstrated that nanotube arrays with uniform morphology and strong interfacial adhesion were obtained under optimized conditions: anodization voltage of 40 V, NH4F mass fraction of 0.5wt%, oxidation duration of 3 h, and a subsequent 5-minute 10 V potential reduction treatment. Following lithiation annealing, lithium titanate nanotubes were successfully synthesized. Acid etching increased the average pore size from 50 nm to 65 nm, while SEM and XPS analyses confirmed the retention of TiO2 nanotube morphology in the ion sieve and the successful fabrication of titanate nanotube arrays. This anodization-lithiation synergistic strategy enabled the construction of titanate-based nanotube arrays, offering valuable insights for developing next-generation high-efficiency lithium extraction materials.

Thermal performance analysis of 18650 battery pack based on thermoelectric cooling

Huimin YU Xiaona MA Huaxia YAN

The Chinese Journal of Process Engineering. 2025, 25(12):  1308-1318.  DOI: 10.12034/j.issn.1009-606X.225082

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Thermoelectric cooler (TEC) can utilize electric energy to realize heat energy transfer directly. With the PID (proportional-integral-derivative)temperature controller, the cold end of the thermoelectric cooler can achieve precise temperature control and meet the needs of battery thermal management. Previous studies primarily emphasize structural optimizations in hybrid battery thermal systems. Few of them have reported the quantitative influence of various factors. This work established a thermoelectric device-battery pack experimental platform. Fluent software was used to establish a battery thermal management model based on thermoelectric cooling, and the accuracy of the model was experimentally verified. A simulation study was carried out to systematically investigate the effects of initial temperatures, cold plate surface temperature, and discharge rate on the thermal characteristics of the battery pack. Within the simulated operating range, increasing the initial temperature of the battery increased the maximum temperature (Tmax) and maximum temperature difference (ΔTmax) during the discharge process. However, the initial temperature of the battery had little effect on the Tmax and ΔTmax at the end of discharge, which were 28.5~28.6 and 3.0℃, respectively. Therefore, the battery could be cooled down first when working in a high-temperature environment. Lowering the surface temperature of the cold plate will reduce the Tmax and increase the ΔTmax during battery discharge. When the surface temperature of the cold plate was 5℃, the Tmax during battery discharge was 17.5℃ and the ΔTmax was 5.4℃. Therefore, the surface temperature of the cold plate should not be too low. Both battery non-uniformity and maximum surface temperature increased with the discharge rate. Sensitivity analysis showed that the highest temperature at the end of battery discharge was sensitive to the cold plate temperature, with an average sensitivity of 0.527. Adjusting cold plate surface temperatures effectively enhanced heat efficiency dissipation in thermoelectric cooling battery management system.

Ultrasonic hydrothermal/ionic liquid-modulated fabrication of Mg-Zr oxide catalyst for dimethyl carbonate synthesis

Qi LIU Qinqin ZHANG Ying LIU Yi LI Qian SU Yifan LIU Yunong LI Zifeng YANG

The Chinese Journal of Process Engineering. 2025, 25(12):  1319-1333.  DOI: 10.12034/j.issn.1009-606X.225108

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The synthesis of dimethyl carbonate (DMC) from CO2 represents a crucial application in C1 chemical conversion, where the alcoholysis of ethylene carbonate (EC) serves as the key step in this route. Although industrial sodium methoxide catalysts exhibit high activity, their strong alkalinity imposes stringent equipment requirements and generates environmental burdens due to non-recyclability and product separation challenges. Bimetal oxide catalysts have emerged as ideal heterogeneous catalytic materials for alcoholysis reactions owing to their tunable Lewis acid-base dual active sites and structural designability. However, current research faces critical scientific issues such as difficulty in synergistic optimization of catalytic activity and stability, unclear structure-activity regulation mechanisms, cumbersome preparation routes, harsh reaction conditions, and insufficient investigation on intensified synthesis strategies for bimetal oxide catalysts, which collectively hinder the design of heterogeneous catalytic systems for DMC synthesis. This study innovatively proposed an ultrasonic hydrothermal-ionic liquid-mediated regulation strategy. By employing the ultrasonic hydrothermal method combined with the ionic liquid [Bmim]BF4 as a structure-directing agent, a Mg-Zr bimetallic oxide catalyst (UIL-MgZrO) with both excellent activity and stability was successfully constructed. The influence mechanisms of the coupling between ionic liquid-mediated processes and different intensified preparation methods on the crystal growth, phase evolution, and surface characteristics of catalysts were systematically investigated, where the gradual transformation of crystals into a stable monoclinic phase with prolonged ultrasonic duration was observed. The operational principles for synergistic regulation of active sites in metal oxides were revealed, thereby improving the catalytic efficiency of bimetallic oxides. In alcoholysis reactions, the UIL-MgZrO catalyst achieved 72.1% EC conversion with 99.9% DMC selectivity under mild conditions (90℃, 1 h), representing top-tier performance among reported heterogeneous catalytic systems. This work provides new strategies for precise regulation of metal oxide surface properties and technical support for CO2-based carbonate synthesis processes, and offers potential applications for energy-related chemical production.

Anion doping induced multi-defect engineering in high-entropy oxides: enhanced structural stability and lithium storage performance

Mengfan BAO Zhengbing WEI Shibiao XU Yi CHENG Shijie CHEN Jie TAN Cuihong ZHENG Na LIN Aiqin MAO

The Chinese Journal of Process Engineering. 2025, 25(12):  1334-1348.  DOI: 10.12034/j.issn.1009-606X.225175

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To enhance the structural stability and electron/ion transport kinetics of high-entropy oxide (HEO) anode materials, a spinel-type (Cr0.2Fe0.2Mn0.2Ni0.2Zn0.2)3O4 HEO is employed as the representative model system. The anionic S-doping strategy is carefully implemented to precisely modulate intrinsic defects and microstructures. A series of mesoporous spinel-type (Cr0.2Fe0.2Mn0.2Ni0.2Zn0.2)3O4-xSx (x=0, 0.15, 0.3, 0.6, 0.9) HEOs with controllable oxygen vacancies, lattice distortion, and interconnected mesoporous frameworks are successfully synthesized via a solution-combustion route using metal nitrates, thiourea, and glycine as metal precursors, sulfur precursor, and fuel, respectively. The optimized (Cr0.2Fe0.2Mn0.2Ni0.2Zn0.2)3O3.7S0.3 (S0.3) electrode delivers a high reversible discharge capacity of 1513 mAh/g after 150 cycles at 200 mA/g, and retains 310 mAh/g after 350 cycles at 1000 mA/g, surpassing most of the previously reported HEO anodes. The superior cycling stability and rate capability arise from two key factors: on the one hand, moderate S2- incorporation increases configurational entropy, mitigates lattice distortion and regulates oxygen vacancy content, collectively ensuring structural integrity during prolonged cycling. The introduction of high configurational entropy combined with defect engineering stabilizes the crystal framework under prolonged cycling while activating redox centers more efficiently, this cooperative effect also minimizes irreversible structural degradation, thereby extending the operational lifespan of the electrode under practical high-rate conditions. On the other hand, synergistic optimization of lattice distortion, oxygen vacancies, and grain size markedly promotes electron/ion transport (S0.3 exhibits the highest electrical conductivity of 22.4 S/m and a relatively large Li+ diffusion coefficient), thereby effectively enhancing the pseudocapacitive contribution. This work demonstrates an effective anion-doping strategy for concurrently optimizing structural stability, electronic conductivity, and ionic mobility in HEOs, while providing an innovative and practical design concept along with a solid experimental foundation for lithium-ion battery anodes with high energy density and long cycling life.