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    28 March 2025, Volume 25 Issue 3
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    Contents
    Cover and Contents
    The Chinese Journal of Process Engineering. 2025, 25(3):  0. 
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    Review
    Effect of alloying elements on RE2Fe14B (RE=Nd, Pr) based nanocomposite permanent magnets
    Chuanyou HUO Dianbao ZHANG Xiaoyu BO Erbao QIAN Zhen ZHANG Jinghan NIU Shengnan JIANG Hailing LI
    The Chinese Journal of Process Engineering. 2025, 25(3):  221-232.  DOI: 10.12034/j.issn.1009-606X.224121
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    Nanocomposite magnets have become a promising next-generation permanent magnet material due to their potential high magnetic energy product. The implementation of high magnetic performance depends on precise control of the microstructure, including the grain size and distribution of soft and hard magnetic phases, the content of soft magnetic phases, the orientation of hard magnetic phases, the structure and chemical composition, etc. At present, the microstructure of nanocomposite magnets is mainly controlled by adjusting the alloy composition and preparation process. By adding alloying elements, not only can improve the microstructure of nanocomposite permanent magnets, but also can change the intrinsic magnetic parameters of the main phase in the magnet, which is a common method to improve the magnetic performance of the magnet. In this work, the role of alloying elements in microstructure control of RE2Fe14B (RE=Nd, Pr) based nanocomposite permanent magnet materials is summarized and evaluated. The addition of rare earth elements (La, Ce, Pr, Dy, Tb, etc.) to replace Nd atoms alters the intrinsic magnetic parameters of Nd2Fe14B phase. Elements such as Co, Cr, Ni, and Mn can enter the lattice of α-Fe and RE2Fe14B to replace by the point position of Fe, while changing the intrinsic magnetic parameters of the soft and hard magnetic phases, thereby altering the magnetic properties of the magnet. It has been confirmed that elements such as Nb, Ti, and Zr can enter the main phase Nd2Fe14B, but are more enriched at grain boundaries, playing a role in enhancing domain wall pinning and refining grain size. Elements such as Sn and Ga can improve the high-temperature magnetic performance of magnets and enhance their thermal stability. Adjusting the alloy composition through the addition of alloying elements is an effective way to control the microstructure of nanocomposite magnets, but the content of alloying elements should be controlled within a certain range. Excessive addition will deteriorate the magnetic properties of the magnets.
    Research Paper
    Heat transfer characteristics of micro-encapsulated phase change material slurry in metal foam filled microchannels
    Yongtong LI Jing SUN Weibo WANG Boyu YANG Yunxi YANG
    The Chinese Journal of Process Engineering. 2025, 25(3):  233-240.  DOI: 10.12034/j.issn.1009-606X.224227
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    Micro-encapsulated phase change material slurry (MEPCMs) is a novel kind of functional thermal fluid, which has great potential in the field of electronic thermal management, thermal storage, etc. To improve the thermal management performance of high-power density electronic devices, a dual-enhanced heat transfer method with the combination of MEPCMs and metal foam was employed to improve the cooling performance of mini-channel heat sink in the present study. Numerical methods were utilized to investigate the heat transfer capability, flow resistance, and overall performance evaluation criteria (PEC) by considering the effects of MEPCMs mass fractions (5wt%, 10wt%, and 20wt%), inlet velocities, and metal foam filling ratios. The results indicated that the maximum temperature of metal foam mini-channel decreased and pressure drop increased with increasing the mass fraction of MEPCMs. At an inlet velocity of 0.06 m/s, increasing the mass fraction from 5wt% to 20wt%, the pressure drop increased by 2.09 times. 5wt% MEPCMs presented the best comprehensive heat transfer performance, and the PEC value was improved by 8.15%~12.18% compared with pure water. The filling ratio of the metal foam also significantly affected the heat transfer performance of the microchannel, and the cooling performance was best when the mini-channel was fully filled with metal foam. For the entire range of flow velocities, using 5wt% MEPCMs as the coolant, average Nuave of mini-channel heat sink fully filled with metal foam was 9.06 times of the empty mini-channel heat sink, and the pressure drop came to 56.91 times. With the comprehensive consideration of heat transfer enhancement and flow resistance, the PEC value could reach up to 2.61. The present findings could provide theoretical guidelines for developing more coefficient and compact liquid-cooled electronic devices.
    Effect of solid phase volume fraction on cavitation characteristics of O-type ball valve
    Zhaonian ZHOU Binbin WU Tingfeng HUA Zhaotong WANG Zhijiang JIN Wenqing LI Jinyuan QIAN
    The Chinese Journal of Process Engineering. 2025, 25(3):  241-248.  DOI: 10.12034/j.issn.1009-606X.224257
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    The O-type ball valve serves as an important fluid control equipment in the coal chemical industry. However, during the operation process, cavitation phenomenon is very easy to occur inside the ball valve which will greatly affect production safety. The working medium of the ball valve is a fluid containing solid particles, and the volume fraction of particles will affect the cavitation, but the mechanism of how the fraction of particles affect cavitation is not clear. In order to solve this problem, numerical simulation is used to investigate the effect of solid phase volume fraction on cavitation in ball valve under different ball angles. The degree of cavitation in the ball valve can be illuminated by the pressure, cavitation number, and gas phase volume fraction on the valve ball outlet section. The results show that when the ball angle is 30° and 45°, there is no cavitation in the valve under any solid phase volume fraction. However, when the ball angle is 60°, different solid phase volume fractions have different effects on cavitation. When the solid phase volume fraction increases from 0% to 10%, the cavitation degree in the ball valve is gradually weakened. When the solid phase volume fraction increased from 10% to 20%, cavitation in the valve gradually increased. In addition, it is interesting that when the valve ball angle reaches 75°, cavitation in the ball valve will be promoted by any solid phase volume fraction. A lot of work has been done in this work to reveal the influence mechanism of solid phase volume fraction and ball valve angles on cavitation characteristics of O-type ball valves, and some useful results have been obtained, which has a certain guiding on controlling the working environment and multi-phase flow simulation of O-type ball valves.
    Numerical simulation study of pulse soot removal characteristics of pleated cartridge based on fluid-solid coupling
    Yifei LI Fuping QIAN Wenyuan HU Qi MA Jinli LU
    The Chinese Journal of Process Engineering. 2025, 25(3):  249-260.  DOI: 10.12034/j.issn.1009-606X.224243
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    Pulse jet airflow is the main means of cleaning dust in the filter cartridge dust collector. The action of the air jet causes the cartridge filter element to expand and shake, and the dust on the cartridge is peeled off and falls into the ash hopper, thus maintaining the clean and efficient filtration performance of the cartridge. In order to more accurately reflect the impact of the blowing airflow on the filter cartridge, the static structural module (Static Structural) in ANSYS Workbench is employed to perform the fluid-solid coupling of the cartridge pulse soot removal, and the resulting pressure is applied to the cartridge. This allows for the conclusions related to the solid mechanics of the filter cartridge under the pressure of pulse blowing to be drawn. By comparing the simulation results with the same blowing time and different blowing distances, the impact of the blowing airflow on the pleated structure of the cartridge can be determined. Firstly, Fluent simulation is employed to obtain the pressure change within the cartridge. It is observed that although the pressure exhibits slight numerical discrepancies under varying blowing distances, its distribution trend remains consistent: the airflow descends along the length of the filter element and subsequently spreads along the radial direction, the static pressure within the cartridge accumulates from the bottom in an upward trajectory. The lower portion of the cartridge exhibits a relatively elevated static pressure, while the upper section displays a comparatively reduced pressure. The accumulation of pressure within the cartridge is discernible. The static structure module in ANSYS Workbench is employed to couple the pressure derived from the Fluent simulation conducted in the preceding step to the pleated structure of the filter cartridge. This enables the acquisition of the total deformation, elastic strain, and maximum shear stress values of the pleated structure of the filter cartridge and their distribution law through simulation under the same time set. In the experimental range, when the blowing distance is 150 mm, the best values of each parameter of the airflow acting on the pleated structure of the cartridge are obtained: the total deformation is 0.133 27 μm, the elastic strain is 3.018×10-4 μm, and the maximum shear stress is 222.69 Pa.
    CFD simulation of bubble columns with tube bundles: impact of turbulence models
    Nan ZHANG Xiaoping GUAN Kangjun WANG Ning YANG
    The Chinese Journal of Process Engineering. 2025, 25(3):  261-272.  DOI: 10.12034/j.issn.1009-606X.224206
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    The accuracy of CFD simulation results for bubble columns depends on closure models, such as interphase force models and turbulence models. Most of the previous reports were for empty column without internals, and currently, there is a lack of studies related to bubble column with internals. This study examined the effects of six commonly used turbulence models (Standard k-ε, RNG k-ε, Realizable k-ε, Standard k-ω, SST k-ω, and RSM) on the hydrodynamics in the pilot-scale bubble columns without internals and with tube bundles. The results showed that the RSM predicted significantly higher for turbulent kinetic energy, turbulent dissipation rate, and turbulent viscosity in the empty column compared to eddy viscosity models (k-ε and k-ω models). However, this difference was considerably reduced in the bubble column with tube bundles, and the tube bundles significantly suppressed the turbulence intensity in the liquid phase. Meanwhile, by comparing the simulated gas holdup and axial liquid velocity values with experimental data, it was found that the eddy viscosity models accurately predicted the gas holdup in the central region of the empty column, while the RSM accurately predicted the gas holdup in all regions except the central region. However, the radial distribution of gas holdup predicted by six turbulence models in the bubble column with tube bundles was almost identical, with accurately predicting the gas holdup only in the 0.5<r/R<0.7 region. The Realizable k-ε model's predictions of axial liquid velocity in both empty column and the bubble columns with tube bundles were in good agreement with experimental data, significantly outperforming other turbulence models. Therefore, it was recommended to use the Realizable k-ε model for future simulations of hydrodynamics in bubble columns.
    Investigation of enhanced boiling heat transfer characteristics of hierarchical gradient porous copper surface
    Er SHI Shuangrui YE Youlan WANG Qi PENG Bin ZHAO Changwei JIANG
    The Chinese Journal of Process Engineering. 2025, 25(3):  273-282.  DOI: 10.12034/j.issn.1009-606X.224233
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    To enhance boiling heat transfer for promoting the efficiency of the energy system, the porous surfaces with structural gradients were developed on pure copper substrates by employing the electrochemical deposition method. In this study, honeycomb-like porous structures and hierarchical axial honeycomb gradient porous structures were fabricated using constant current single-step deposition and constant current constant voltage two-step deposition methods, respectively. Saturated pool boiling heat transfer experiments were conducted using HFE-7100 as the working fluid to investigate the influence of the gradient pore size changes on the boiling heat transfer performance of porous surfaces. The results demonstrated that the hierarchical gradient porous surface, which had a total deposition time of 60 seconds and an increased second-step deposition voltage of 3 V, showed the most significant heat transfer enhancement. The wall superheat at the boiling initiation point was 9.5 K, a 43.00% decrease compared to the smooth surface at 16.8 K. Moreover, the critical heat flux and heat transfer coefficient reached 522.02 kW/m2 and 22.76 kW/(m2?K), respectively, exhibiting with enhancements of 193.40% and 261.01% compared to the smooth surface. The hierarchical porous surface had two types of nucleation sites: internal pores and dendritic protrusions. The micropores and the internal micropores of the dendrites exhibited a wide range of pore sizes. This extensive distribution of pore sizes not only increased the density of nucleation sites and effective heat transfer area but also reduced the nucleation energy barrier. The axial pore size gradient accelerated bubble evolution, and the capillary suction force provided by the gradient porous structure and dendrites facilitated the return flow of the working fluid to the nucleation sites both horizontally and vertically, thereby enhancing the boiling heat transfer coefficient and critical heat flux of the hierarchical gradient porous surface.
    Numerical study on influence of pulse amplitude on patterns of gas-liquid-liquid three-phase flow in pulsed extraction column with discs and doughnuts
    Ting YU Xiucheng YU Zonghui LU Zhe XIAO Ming QU Hui HE Guoan YE
    The Chinese Journal of Process Engineering. 2025, 25(3):  283-292.  DOI: 10.12034/j.issn.1009-606X.224194
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    The pulsed extraction columns with discs and doughnuts play a critical role in the field of spent fuel reprocessing. The countercurrent contact between liquid-liquid two-phase fluids in the column is facilitated through periodic pulses, which significantly influences the separation and purification processes of chemical elements. Although a considerable amount of research on pulse extraction columns with discs and doughnuts has been conducted through simulation, few studies have utilized the actual industrial structure of these columns as examples. A gas-liquid-liquid three-phase flow model coupled with PBM (Polulation Balance Model) to evaluate discrete phase droplet diameter distribution, reflecting the actual structure of pulsed extraction column with discs and doughnuts, was established using CFD (Computational Fluid Dynamics) simulation technology. And it verified the accuracy of the modeling through multiple calculation cases, aiming to investigate the influence of pulse amplitude on the evolution of flow field inside a pulsed extraction column. The model's accuracy was demonstrated through comparison with public literature, and the impact of pulse amplitude on the micro-flow behavior inside the pulsed extraction column was calculated, analyzed and verified. Under the working condition with a pulse amplitude of 1.2 cm, the amplitude had a relatively small impact on the motion of water and oil phases, and the water phase accumulated on the baffle. Under the working conditions of pulse amplitudes of 7.2 and 14.4 cm, the amplitude had a significant impact on the direction and velocity of the water and oil phases, with the water phase separating from the baffle and dispersing into smaller droplets. Furthermore, it was found that as the pulse amplitude increased, both the turbulence kinetic energy and turbulence energy dissipation rate also increased, reaching a maximum value in the region where the fluid impacted the solid wall. Finally, from the distribution of droplet diameter fraction, it was evident that as the pulse amplitude increased, the proportion of small diameter aqueous droplets was higher, which enhanced the extraction. This study used the Euler-Euler two-phase flow model coupled with the PBM to accurately simulate the gas-liquid-liquid three-phase evolution phenomenon in pulse extraction columns, providing a reference for the design and process optimization of subsequent pulsed baffle extraction columns, which laid the foundation for introducing the mass transfer model and heat transfer model through CFD method to analyze the chemical process inside the column in further study.
    Optimization of phosphorus release from anaerobic fermentation of cow manure and phosphorus recovery through vivianite crystallization
    Zhihao CHEN Weihua LI Tingting YANG Yixin LIU
    The Chinese Journal of Process Engineering. 2025, 25(3):  293-301.  DOI: 10.12034/j.issn.1009-606X.224223
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    With the rapid development of the livestock and poultry farming industry in China, the disposal and resource utilization of livestock and poultry waste have attracted widespread attention. To maximize the recovery of phosphorus from this waste, this study focuses on fresh cow manure, which is rich in phosphorus, and proposes a novel pathway for phosphorus recovery. By examining the effects of different manure concentrations, anaerobic fermentation durations, and initial pH values on phosphorus release during the anaerobic fermentation of fresh cow manure, the study found that optimal conditions for phosphorus release were achieved with a manure concentration of 180 g/L, an anaerobic fermentation period of 14 days, and the initial pH of 7, resulting in a phosphorus release of 156.57 mg/L. To recover phosphorus from the supernatant of anaerobically fermented cow manure, Fe2+ salts were added to induce the vivianite crystallization. L9(34) orthogonal experiments were conducted to investigate the effects of reaction temperature, pH, and Fe/P ratio on the phosphorus recovery rate. The results showed that the factors affecting phosphorus recovery efficiency in order of significance, were the initial pH value, reaction temperature, and Fe/P ratio. The optimal for the process were found to be a reaction temperature of 35℃, a pH of 7, and a Fe/P ratio of 1.9. Under these conditions, the highest phosphorus recovery rate of 84.20% was achieved, and the purity of vivianite was 25%. The recovered products were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. An improved sequential phosphorus extraction method was employed to determine the abundance of vivianite in the recovered products. The research provides a valuable reference for the synthesis of high-value vivianite, based on the effective extraction of phosphorus from fresh cow manure.
    Influence of alumina on reactivity of biopitch anode for aluminum electrolysis
    Kunmo ZHANG Wei WANG
    The Chinese Journal of Process Engineering. 2025, 25(3):  302-310.  DOI: 10.12034/j.issn.1009-606X.224254
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    The carbon anode is prepared by baking a mixture of petroleum coke aggregate and pitch at 180℃ for use in the aluminum industry. Due to its good wettability and environmental friendliness towards carbon anode aggregates, the biopitch is considered as a promising carbon anode binder. The biomass conversion technology, substituting traditional coal tar pitch with biopitch, partially or completely in the aluminum production, has recently received domestic and foreign researchers' attention. However, the biopitch typically has a lower coking value which may have a negative impact on its performance. In this work, alumina additives have been added to the biopitch anode to improve its performance. In order to understand the effect of alumina additives on the performance of biopitch anodes, biopitch anode materials were prepared by hot pressing and sintering in the laboratory with alumina as a catalyst. The CO2 reactivity of the anodes was tested with a thermogravimetric analyzer in laboratory. The influence of additives on the performance of the anodes and the CO2 reactivity as well as the wettability of biopitch on petroleum coke were studied by X-ray diffraction analysis, optical microscopy (OM) and high-resolution transmission electron microscopy (HRTEM). The results indicated that the biopitch exhibited better wettability than coal tar pitch with the same surface tension and viscosity. In addition, a transformation occurred from initially less well-ordered to ordered structure for the biopitch anode with alumina additives during baking, thereby increasing the coking value of the biopitch, reducing the CO2 reactivity of biopitch anodes and improving their antioxidant properties. Accompanied by an enhancement in the graphitization degree and an increase of carbon structural orders, the performance of biopitch anodes has been improved significantly with alumina as additives. The biopitch could be used to replace 100% of the coal tar pitch in a carbon anode recipe. This study has provided a theoretical guidance for the application of biopitch anodes and the reduction of energy consumption in aluminum electrolysis.
    Preparation, characterization and release properties in vitro of altrenogest nanosuspension drug delivery system
    Chao LI Dongbo LI Yueli WANG Haiyan ZHAO Junhao ZHANG Hualin FU
    The Chinese Journal of Process Engineering. 2025, 25(3):  311-322.  DOI: 10.12034/j.issn.1009-606X.224240
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    Altrenogest (ALT) is oral progestin with poor solubility (~10 μg/mL) and rapid metabolism in vivo, which severely constraints on clinical effectiveness. Nanosuspension drug delivery systems (NS) can reduce the drug particles to nanometer size and improve the solubility and bioactivity of insoluble drugs. The factors and mechanism of altrenogest nanosuspension (ALT-NS) formation were analyzed and investigated using the anti-solvent precipitation method and its quality was evaluated. The preparation process and prescription composition were analyzed and optimized using single factor experiments and the central composite design-response surface methodology (CCD-RSM), and the experiments of characterization, chemical structure analysis, crystalline shape examination, physical stability and release experiments in vitro were applied to evaluate the quality of ALT-NS. The optimal prescription and process were determined as follows: altrenogest 0.4wt%, sodium dodecyl sulfate (SDS) 25 mg/mL, hypromellose (HPMC) 4 mg/mL, stirring speed of 1000 r/min, and stirring time of 10 minutes. The formulation was a light yellow clarified liquid, and the drug particles were in the form of spherical particles with an average particle size of 104.87±1.10 nm, PDI (particle size distribution index) of 0.19±0.01, and Zeta potential of -37.87±0.81 mV, the drug was transformed from crystalline to amorphous state, and the use of freeze-drying technology to make ALT-NS into freeze-dried powder could further improve its physical stability. The cumulative release of the preparation group in vitro was 98.4% at 72 h,which was about 1.54 times higher than that of the original group, showing high efficiency and smooth drug release. In conclusion, the optimization of the prescription composition and preparation process of ALT-NS using the anti-solvent precipitation method can significantly reduce the physical size and specific surface area of ALT, improve the dissolution and release efficiency of ALT, and the formulation has the efficient and fast drug release characteristics, which is expected to provide a reference for the clinical application of ALT-NS.