Processes

24 pages, 2138 KiB

Open AccessArticle

Research on Dynamic Calculation Methods for Deflection Tools in Deepwater Shallow Soft Formation Directional Wells

by Yufa He, Yu Chen, Xining Hao, Song Deng and Chaowei Li

Processes 2025, 13(6), 1947; https://doi.org/10.3390/pr13061947 - 19 Jun 2025

The shallow, soft subsea formations, characterized by low strength and poor stability, lead to complex interactions between the screw motor drilling tool and the wellbore wall during directional drilling, complicating the accurate evaluation of the tool’s deflection capability. To address this issue, this [...] Read more.

The shallow, soft subsea formations, characterized by low strength and poor stability, lead to complex interactions between the screw motor drilling tool and the wellbore wall during directional drilling, complicating the accurate evaluation of the tool’s deflection capability. To address this issue, this paper proposes an integrated mechanical analysis method combining three-dimensional finite element analysis and transient dynamic analysis. By establishing a finite element model using 12-DOF (degree-of-freedom) spatial rigid-frame Euler–Bernoulli beam elements, coupled with well trajectory coordinate transformation and Rayleigh damping matrix, a precise description of drill string dynamic behavior is achieved. Furthermore, the introduction of pipe–soil dynamics and the p-y curve method improves the calculation of contact reaction forces between drilling tools and formation. Case studies demonstrate that increasing the tool face rotation angle intensifies lateral forces at the bit and stabilizer, with the predicted maximum dogleg severity within the first 10 m ahead of the bit progressively increasing. When the tool face rotation angle exceeds 2.5°, the maximum dogleg severity reaches 17.938°/30 m. With a gradual increase in the drilling pressure, the maximum bending stress on the drilling tool, maximum lateral cutting force, and stabilizer lateral forces progressively decrease, while vertical cutting forces and bit lateral forces gradually increase. However, the predicted maximum dogleg severity increases within the first 10 m ahead of the bit remain relatively moderate, suggesting the necessity for the multi-objective optimization of drilling pressure and related parameters prior to actual operations. Full article

(This article belongs to the Special Issue Modeling, Control, and Optimization of Drilling Techniques)

16 pages, 4597 KiB

Open AccessArticle

Growth Mechanisms of Small-Displacement Strike–Slip Faults in Cratonic Basins: Insights from Material Point Method Simulations

by Changsheng Li, Shuangjian Li, Zongquan Hu, Jian Gao, Butao Shi and Yu Chi

Processes 2025, 13(6), 1946; https://doi.org/10.3390/pr13061946 - 19 Jun 2025

Abstract

Exploration in the Tarim Craton has established that small-displacement strike–slip faults control carbonate reservoirs’ development and oil and gas accumulation. Oil and gas primarily accumulate within a defined lateral distance from these faults. Material point method (MPM) simulations of such fault systems revealed [...] Read more.

Exploration in the Tarim Craton has established that small-displacement strike–slip faults control carbonate reservoirs’ development and oil and gas accumulation. Oil and gas primarily accumulate within a defined lateral distance from these faults. Material point method (MPM) simulations of such fault systems revealed a functional relationship between the regular spacing of initial oblique Riedel fractures and brittle layer thickness under simple shear. This thickness critically governs the spatial organization of the resultant fault system. Riedel shear zones propagate upwards from the base in a semi-elliptical pattern, producing fewer, but longer, shear zones with increasing brittle layer thickness. Stratum thickness exerts a first-order control on fault configuration during strike-slip deformation, modulating both fault segmentation patterns and interconnectivity. Key quantitative relationships emerged: (1) an inverse proportionality between stratum thickness and Riedel shear zone density and (2) a positive correlation between shear zone length and stratum thickness. This article provides experimental evidence and theoretical guidance for exploring deep-seated strike-slip faults in cratonic basins. Full article

(This article belongs to the Special Issue Advanced Reservoir Simulation and Modelling in Oil and Gas-Related Processes)

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15 pages, 578 KiB

Open AccessReview

Utilization of Agro-Industrial Residues from the Rosa damascena Mill. Oil Industry: A Literature Review on Biomass Potential for Food and Feed Ingredients

by Nikolay Kolev, Mihaela Ivanova, Alexandar Balabanov, Desislava Vlahova-Vangelova, Aneta Kišová and Francesco Vizzarri

Processes 2025, 13(6), 1945; https://doi.org/10.3390/pr13061945 - 19 Jun 2025

Abstract

The re-usage of byproducts needs urgent attention as the recycling and reduction in wastes can minimize environmental pollution and ameliorate the present situation by creating new products, such as animal feed and ingredients for the food industry. The industrial production of rose oil [...] Read more.

The re-usage of byproducts needs urgent attention as the recycling and reduction in wastes can minimize environmental pollution and ameliorate the present situation by creating new products, such as animal feed and ingredients for the food industry. The industrial production of rose oil from Rosa damascena Mill. generates tons of byproducts, due to the low oil yield. Byproducts such as spent petals are systematically used as feed supplements, while the polyphenol-rich extracts are incorporated in numerous animal products. Among their benefits, exogenous (through a dietary strategy) antioxidants such as polyphenols, play a pivotal role in the antioxidant system in intensive farmed animals—influencing the growth performance and increasing the feed conversion. On the other hand, incorporated extracts serve as natural antioxidants retaining the discoloration of meat products, as well as inhibiting the lipid and protein oxidation during storage, extending their shelf-life. Rosa damascena Mill. extracts are used as additives in functional and more healthier products with reduced nitrite content and enhanced the biological value of the consumed products. The aim is to systematize the existing knowledge about the potential use of spent Rosa damascena Mill. petals and their extracts, as well as highlight the need for further research in dairy and meat products. Full article

(This article belongs to the Special Issue Exploring the Antibacterial, Anti-Inflammatory and Antioxidant Properties of Natural Products in Drug Discovery and Development)

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18 pages, 6242 KiB

Open AccessArticle

Eco-Efficient Mortars with High-Content Construction, Waste-Derived Aggregates Functionalized via Nano-TiO₂ for NOx Abatement

by Xiu-Cheng Zhang and Xue-Fei Chen

Processes 2025, 13(6), 1944; https://doi.org/10.3390/pr13061944 - 19 Jun 2025

Abstract

This study elucidates the photocatalytic NOx abatement efficacy of eco-efficient mortars incorporating construction waste-derived aggregates functionalized with nano-TiO₂. The research findings demonstrate a positive correlation between NOx abatement efficiency and nano-TiO₂ substitution ratio, with recycled glass sand (RG)-based panels exhibiting [...] Read more.

This study elucidates the photocatalytic NOx abatement efficacy of eco-efficient mortars incorporating construction waste-derived aggregates functionalized with nano-TiO₂. The research findings demonstrate a positive correlation between NOx abatement efficiency and nano-TiO₂ substitution ratio, with recycled glass sand (RG)-based panels exhibiting superior performance compared to standard sand and recycled clay brick sand (RCBS)-based counterparts. The employment of ultrasonic dispersion as a nano-TiO₂ incorporation method yields enhanced abatement efficiency relative to direct mixing, attributable to improved photocatalyst dispersion and surface area accessibility. The loading capacity of nano-TiO₂ on recycled aggregates is observed to be positively influenced by the concentration of nano-TiO₂ solution, with recycled clay brick sand demonstrating the highest loading capacity. RG-RCBS panels are shown to exhibit higher NOx abatement efficiency than standard sand (SS)-RCBS panels, with an optimal substitution ratio of 40% glass sand identified for maximizing abatement efficacy in RG-RCBS systems. A decline in NOx abatement efficiency is observed with increasing NOx flow rate and concentration, attributable to reduced pollutant residence time and excess pollutant load exceeding the panels’ processing capacity. Prolonged curing time also results in diminished abatement efficiency, due to microstructural alterations within the mortar matrix and the accumulation of photocatalytic reaction byproducts. Collectively, these findings underscore the potential of recycled aggregate-based mortars, in conjunction with nano-TiO₂, as a viable eco-efficient strategy for NOx abatement, highlighting the critical influence of material selection, photocatalyst loading, and operational parameters on system performance. Full article

(This article belongs to the Section Materials Processes)

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24 pages, 1808 KiB

Open AccessArticle

Research on the Low-Carbon Economic Operation Optimization of Virtual Power Plant Clusters Considering the Interaction Between Electricity and Carbon

by Ting Pan, Qiao Zhao, Jiangyan Zhao and Liying Wang

Processes 2025, 13(6), 1943; https://doi.org/10.3390/pr13061943 - 19 Jun 2025

Abstract

Under carbon emission constraints, to promote low-carbon transformation and achieve the aim of carbon peaking and carbon neutrality in the energy sector, this paper constructs an operational optimization model for the coordinated operation of a virtual power plant cluster (VPPC). Considering the resource [...] Read more.

Under carbon emission constraints, to promote low-carbon transformation and achieve the aim of carbon peaking and carbon neutrality in the energy sector, this paper constructs an operational optimization model for the coordinated operation of a virtual power plant cluster (VPPC). Considering the resource characteristics of different virtual power plants (VPPs) within a cooperative alliance, we propose a multi-VPP interaction and sharing architecture accounting for electricity–carbon interaction. An optimization model for VPPC is developed based on the asymmetric Nash bargaining theory. Finally, the proposed model is solved using an alternating-direction method of multipliers (ADMM) algorithm featuring an improved penalty factor. The research results show that P2P trading within the VPPC achieves resource optimization and allocation at a larger scale. The proposed distributed ADMM solution algorithm requires only the exchange of traded electricity volume and price among VPPs, thus preserving user privacy. Compared with independent operation, the total operation cost of the VPPC is reduced by 20.37%, and the overall proportion of new energy consumption is increased by 16.83%. The operation costs of the three VPPs are reduced by 1.12%, 20.51%, and 6.42%, respectively, while their carbon emissions are decreased by 4.47%, 5.80%, and 5.47%, respectively. In addition, the bargaining index incorporated in the proposed (point-to-point) P2P trading mechanism motivates each VPP to enhance its contribution to the alliance to achieve higher bargaining power, thereby improving the resource allocation efficiency of the entire alliance. The ADMM algorithm based on the improved penalty factor demonstrates good computational performance and achieves a solution speed increase of 15.8% compared to the unimproved version. Full article

(This article belongs to the Special Issue Evaluation, Decision–Making and Market Simulation of a New Type of Power System)

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15 pages, 2596 KiB

Open AccessArticle

Evaluation of Particle and Nanoparticle Emissions in Fiber and CO₂ Laser Cutting Processes

by Noemi Paulin, Roberta Pernetti, Fabrizio Scafa, Stefano M. Candura and Enrico Oddone

Processes 2025, 13(6), 1942; https://doi.org/10.3390/pr13061942 - 19 Jun 2025

Abstract

Laser cutting processes entail the cutting of metal sheets by the emission of a laser source that melts the material along defined paths, potentially generating incidental metal nanoparticles (IMNPs). These particles have been associated with genotoxicity, oxidative stress, and pro-inflammatory responses. However, quantitative [...] Read more.

Laser cutting processes entail the cutting of metal sheets by the emission of a laser source that melts the material along defined paths, potentially generating incidental metal nanoparticles (IMNPs). These particles have been associated with genotoxicity, oxidative stress, and pro-inflammatory responses. However, quantitative data on IMNP emissions remain limited. This study assessed IMNP emissions from CO₂ and fiber laser cutting through two monitoring days at a high-precision metalworking facility in Italy. The first day dealt with environmental monitoring, while the second included both personal and environmental monitoring. Personal sampling consistently indicated elevated particle number concentrations and lung-deposited surface area, with average values reaching up to five times the background level (161,960 n/cm³) and peak concentrations as high as 2,781,962 particles/cm³. Environmental concentrations increased significantly only during CO₂ stainless steel cutting (95,670 n/cm³). Depending on the process, 73–89% of the emitted particles were <300 nm, with substantial enrichment in the nanoparticle fraction. Emission profiles varied by laser source, metal, and sheet thickness, with the highest concentrations recorded during CO₂-laser cutting of stainless steel. These findings provide preliminary evidence of occupational exposure to IMNPs during laser cutting and highlight the need for systematic exposure assessments to quantify the potential occupational health risk. Full article

(This article belongs to the Special Issue Progress in Laser-Assisted Manufacturing and Materials Processing)

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28 pages, 840 KiB

Open AccessPerspective

Decarbonizing the Industry Sector: Current Status and Future Opportunities of Energy-Aware Production Scheduling

by Georgios P. Georgiadis, Christos N. Dimitriadis and Michael C. Georgiadis

Processes 2025, 13(6), 1941; https://doi.org/10.3390/pr13061941 - 19 Jun 2025

Abstract

As industries come under growing pressure to minimize carbon emissions without compromising the efficiency of operations, the integration of energy-aware production scheduling with emerging energy markets, renewable energy, and policy mechanisms is critical. This paper identifies critical shortcomings in current academic and industrial [...] Read more.

As industries come under growing pressure to minimize carbon emissions without compromising the efficiency of operations, the integration of energy-aware production scheduling with emerging energy markets, renewable energy, and policy mechanisms is critical. This paper identifies critical shortcomings in current academic and industrial approaches—namely, an excessive reliance on deterministic assumptions, a limited focus on dynamic operational realities, and the underutilization of regulatory mechanisms such as carbon trading. We advocate for a paradigm shift to more robust, adaptable, and policy-compliant scheduling systems that provide space for on-site renewable generation, battery energy storage systems (BESSs), demand-response measures, and real-time electricity pricing schemes like time-of-use (TOU) and real-time pricing (RTP). By integrating recent advances and their critical analysis of limitations, we map out a future research agenda for the integration of uncertainty modeling, machine learning, and multi-level optimization with policy compliance. In this paper, we propose the need for joint efforts from researchers, industries, and policymakers to collectively develop industrial scheduling systems that are both technically efficient and adherent to sustainability and regulatory requirements. Full article

(This article belongs to the Section Energy Systems)

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14 pages, 3860 KiB

Open AccessArticle

Large Eddy Simulations on the Diffusion Features of the Cold-Vented Natural Gas Containing Sulfur

by Xu Sun, Meijiao Song, Sen Dong, Dongying Wang, Yibao Guo, Jinpei Wang and Jingjing Yu

Processes 2025, 13(6), 1940; https://doi.org/10.3390/pr13061940 - 19 Jun 2025

Abstract

For cold venting processes frequently employed in oil and gas fields, precisely predicting the instantaneous diffusion process of the vented explosive and/or toxic gases is of great importance, which cannot be captured by the Reynolds-averaged Navier–Stokes (RANS) method. In this paper, the large [...] Read more.

For cold venting processes frequently employed in oil and gas fields, precisely predicting the instantaneous diffusion process of the vented explosive and/or toxic gases is of great importance, which cannot be captured by the Reynolds-averaged Navier–Stokes (RANS) method. In this paper, the large eddy simulation (LES) method is introduced for gas diffusion in an open space, and the diffusion characteristics of the sulfur-containing natural gas in the cold venting process is analyzed numerically. Firstly, a LES solution procedure of compressible gas diffusion is proposed based on the ANSYS Fluent 2022, and the numerical solution is verified using benchmark experiments. Subsequently, a computational model of the sulfur-containing natural gas diffusion process under the influence of a wind field is established, and the effects of wind speed, sulfur content, the venting rate and a downstream obstacle on the natural gas diffusion process are analyzed in detail. The results show that the proposed LES with the DSM sub-grid model is able to capture the transient diffusion process of heavy and light gases released in turbulent wind flow; the ratio between the venting rate and wind speed has a decisive influence on the gas diffusion process: a large venting rate increases the vertical diffusion distance and makes the gas cloud fluctuate more, while a large wind speed decreases the vertical width and stabilizes the gas cloud; for an obstacle located closely downstream, the venting pipe makes the vented gas gather on the windward side and move toward the ground, increasing the risk of ignition and poisoning near the ground. The LES solution procedure provides a more powerful tool for simulating the cold venting process of natural gas, and the results obtained could provide a theoretical basis for the safety evaluation and process optimization of sulfur-containing natural gas venting. Full article

(This article belongs to the Section Energy Systems)

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19 pages, 4187 KiB

Open AccessArticle

Development of pH-Sensing Starch and Carrageenan Biodegradable Films Incorporated with Grape and Acerola Industrial Residues

by Mayara Lima Goiana, Glácio Souza Araujo and Fabiano André Narciso Fernandes

Processes 2025, 13(6), 1939; https://doi.org/10.3390/pr13061939 - 19 Jun 2025

Abstract

This research has explored the development of pH-sensing starch and carrageenan films incorporated with grape pomace and acerola residue extracts. The main goal was to improve the films’ physicochemical properties and induce pH-sensing capabilities. This study has evaluated the pH-sensing capabilities of the [...] Read more.

This research has explored the development of pH-sensing starch and carrageenan films incorporated with grape pomace and acerola residue extracts. The main goal was to improve the films’ physicochemical properties and induce pH-sensing capabilities. This study has evaluated the pH-sensing capabilities of the films as well as important properties such as amylose content, moisture content, solubility, contact angle, surface morphology, and chemical group profiling. The film incorporated with grape pomace extracts presented satisfactory colorimetric pH indication, while the response of the film incorporated with acerola residue extract was less intense. Integrating natural pigments such as acerola carotenoids and grape pomace anthocyanins enhanced the functional properties of the films and enabled visual indication of food freshness through pH-sensing ability. Full article

(This article belongs to the Special Issue Extraction, Modification, Synthesis, Characterization, and Application of Natural and Biobased Polymer Materials)

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23 pages, 5003 KiB

Open AccessArticle

Analysis of the Flame-Arresting Performance of Pipeline Flame Arresters with Solid Particle Deposition

by Qian Huang, Jiangtao Xiao, Rui Liao, Yuxin Xie, Xueyuan Long and Cheng Zeng

Processes 2025, 13(6), 1938; https://doi.org/10.3390/pr13061938 - 19 Jun 2025

Abstract

In gas transmission stations, flame arrestors are typically installed in pipelines and venting systems to prevent the flames resulting from accidental ignition or deflagration of combustible gases during transmission from propagating through the pipelines. During actual operation, the presence of solid particulates in [...] Read more.

In gas transmission stations, flame arrestors are typically installed in pipelines and venting systems to prevent the flames resulting from accidental ignition or deflagration of combustible gases during transmission from propagating through the pipelines. During actual operation, the presence of solid particulates in the gas compromises the flame-arresting efficacy and increases the failure rate of current pipeline flame arrestors. This study employs an integrated approach combining theoretical analysis and numerical simulation to establish a numerical model for flame arrestors that accounts for solid particle deposition effects. The model reveals the distribution characteristics of velocity fields, pressure fields, gas phase volumetric concentration fields, and solid deposition rate fields within pipeline flame arrestors. It systematically investigates the influence mechanisms of porosity, flame arrestor core thickness, inlet flame velocity, arrestor length, particle size, particle concentration on pressure drop, flame arrestment velocity, and deposition rate. These findings provide theoretical support for optimizing flame arrestor structural design and reducing operational failure rates. Full article

(This article belongs to the Section Chemical Processes and Systems)

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11 pages, 1292 KiB

Open AccessFeature PaperArticle

Effects of Flue Gas Desulfurization Gypsum and Coal Fly Ash Treatments on Coastal Saline Soils in China: A Field Study

by Dawei Hou, Jingnan Zhang, Xin Wang, Hao Wu, Lingxiao Zhan and Wenrui Li

Processes 2025, 13(6), 1937; https://doi.org/10.3390/pr13061937 - 19 Jun 2025

Abstract

Soil salinization in coastal areas is a serious problem restricting agricultural development. This field study aimed to explore the effects of flue gas desulfurization gypsum (FGDG) and coal fly ash (CFA) in combination with irrigation on coastal saline soils in China. Six different [...] Read more.

Soil salinization in coastal areas is a serious problem restricting agricultural development. This field study aimed to explore the effects of flue gas desulfurization gypsum (FGDG) and coal fly ash (CFA) in combination with irrigation on coastal saline soils in China. Six different treatments (C1–C4: FGDG 4.5–15.0 t/hm²; C5 and C6: FGDG 4.5 t/hm² combined with CFA 2.0 and 3.5 t/hm²) were established, and soil properties such as pH, electrical conductivity (EC), and organic matter (OM) content were analyzed. The results showed that compared with the control group, the addition of FGDG (4.5 t/hm² to 15 t/hm²) slightly increased the soil pH, and the combined application of FGDG and CFA made the soil pH closer to neutral. The application of FGDG combined with two rounds of irrigation could reduce the soil EC, and the mixed application of FGDG and CFA further reduced the soil EC by about 6.7% in the 0–20 cm layer. The application of FGDG combined with irrigation showed no significant effect on the soil OM content. In general, the moderate application of FGDG and CFA can effectively improve the physicochemical properties of soil, potentially contributing to more sustainable agricultural practices in coastal regions. Full article

(This article belongs to the Special Issue Development and Utilization of Biomass, Coal and Organic Solid Wastes)

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24 pages, 7889 KiB

Open AccessArticle

Machine Learning-Driven Multi-Objective Optimization of Enzyme Combinations for Plastic Degradation: An Ensemble Framework Integrating Sequence Features and Network Topology

by Ömer Akgüller and Mehmet Ali Balcı

Processes 2025, 13(6), 1936; https://doi.org/10.3390/pr13061936 - 19 Jun 2025

Abstract

Plastic waste accumulation presents critical environmental challenges demanding innovative circular economy solutions. This study developed a comprehensive machine learning framework to systematically identify optimal enzyme combinations for polyester depolymerization. We integrated kinetic parameters from the BRENDA database with sequence-derived features and network topology [...] Read more.

Plastic waste accumulation presents critical environmental challenges demanding innovative circular economy solutions. This study developed a comprehensive machine learning framework to systematically identify optimal enzyme combinations for polyester depolymerization. We integrated kinetic parameters from the BRENDA database with sequence-derived features and network topology metrics to train ensemble classifiers predicting enzyme-substrate relationships. A multi-objective optimization algorithm evaluated enzyme combinations across four criteria: prediction confidence, substrate coverage, operational compatibility, and functional diversity. The ensemble classifier achieved 86.3% accuracy across six polymer families, significantly outperforming individual models. Network analysis revealed a modular organization with hub enzymes exhibiting broad substrate specificity. Multi-objective optimization identified 156 Pareto-optimal enzyme combinations, with top-ranked pairs achieving composite scores exceeding 0.89. The Cutinase–PETase combination demonstrated exceptional complementarity (score:

0.875 \pm 0.008

), combining complete substrate coverage with high catalytic efficiency. Validation against experimental benchmarks confirmed enhanced depolymerization rates for recommended enzyme cocktails. This framework provides a systematic approach for enzyme prioritization in plastic valorization, advancing biological recycling technologies through data-driven biocatalyst selection while identifying key economic barriers requiring technological innovation. Full article

(This article belongs to the Special Issue Circular Economy on Production Processes and Systems Engineering)

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26 pages, 5687 KiB

Open AccessArticle

Importance Analyses on Phenomenological Parameters for the Aerosol Dynamics Models in I-COSTA for a Severe Nuclear Power Plant Accident

by Yoonhee Lee

Processes 2025, 13(6), 1935; https://doi.org/10.3390/pr13061935 - 19 Jun 2025

Abstract

In this study, using in-house code I-COSTA, importance analyses are performed on the phenomenological parameters in the aerosol dynamics using International Standard Problem No. 44. The analyses consider twelve parameters used in multicomponent sectional equations and Mason equations. For the first step of [...] Read more.

In this study, using in-house code I-COSTA, importance analyses are performed on the phenomenological parameters in the aerosol dynamics using International Standard Problem No. 44. The analyses consider twelve parameters used in multicomponent sectional equations and Mason equations. For the first step of the analysis, Latin hypercube sampling is performed for the aforementioned parameters, and the number of samplings is determined using a comparison of averages and standard deviations between those samplings and the ones gathered from continuous distributions of the parameters. Sensitivity analyses are then performed on the airborne concentrations of the aerosol particles using I-COSTA, and the results are used to obtain the correlation coefficients between the parameters and the airborne concentrations. From the analyses, the dynamic shape factor, which accounts for the drag force of the non-spherical aerosol particles, is found to be one of the most important parameters in the aerosol dynamics. The saturation ratio in the Mason equation is also found to be an important parameter for aerosol particles with high solubility since the mass of the aforementioned particles is sensitive to the hygroscopic growth rate. Full article

(This article belongs to the Section Chemical Processes and Systems)

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18 pages, 1488 KiB

Open AccessArticle

Study on Seepage Model of Staged-Fractured Horizontal Well in Low Permeability Reservoir

by Jian Song, Zongxiao Ren, Zhan Qu, Xinzhu Wang, Jiajun Cao, Xuemei Luo and Miao Wang

Processes 2025, 13(6), 1934; https://doi.org/10.3390/pr13061934 - 18 Jun 2025

Viewed by 35

Abstract

This study addresses the coupled influence of the threshold pressure gradient and stress sensitivity during the seepage process in low-permeability reservoirs. By integrating Laplace transform, perturbation transform, the image principle, and the superposition principle, a non-steady-state seepage model for segmented-fractured horizontal wells considering [...] Read more.

This study addresses the coupled influence of the threshold pressure gradient and stress sensitivity during the seepage process in low-permeability reservoirs. By integrating Laplace transform, perturbation transform, the image principle, and the superposition principle, a non-steady-state seepage model for segmented-fractured horizontal wells considering both effects is established for the first time. The analytical solution of the point source function including the threshold pressure gradient (

λ

) and stress sensitivity effect (permeability modulus

α

) is innovatively derived and extended to closed-boundary reservoirs. The model accuracy is verified by CMG numerical simulation (with an error of only 1.02%). Based on this, the seepage process is divided into four stages: I linear flow (pressure derivative slope of 0.5), II fracture radial flow (slope of 0), III dual radial flow (slope of 0.36), and IV pseudo-radial flow (slope of 0). Sensitivity analysis indicates the following: (1) The threshold pressure gradient significantly increases the seepage resistance in the late stage (the pressure curve shows a significant upward curvature when

λ

= 0.1 MPa/m); (2) Stress sensitivity dominates the energy dissipation in the middle and late stages (a closed-boundary-like feature is presented when

α

> 0.1 MPa⁻¹); (3) The half-length of fractures dominates the early flow (a 100 m fracture reduces the pressure drop by 40% compared to a 20 m fracture). This model resolves the accuracy deficiency of traditional single-effect models and provides theoretical support for the development effect evaluation and well test interpretation of fractured horizontal wells in low-permeability reservoirs. Full article

(This article belongs to the Section Energy Systems)

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18 pages, 4291 KiB

Open AccessArticle

Parametric Effects of Mixing Channel Geometry on Entrainment Characteristics of Ejector in R410A Heat Pump Systems

by Yuying Wang, Zhengdao Zhou, Meiyuan Yang, Li Chang, Yang Li and Zhenying Zhang

Processes 2025, 13(6), 1933; https://doi.org/10.3390/pr13061933 - 18 Jun 2025

Viewed by 52

Abstract

The two-phase ejector has gained prominence in heat pump systems as a device that effectively mitigates throttling losses through expansion work recovery. This investigation employs three-dimensional computational fluid dynamics (CFD) simulations to analyze the parametric effects of the mixing channel geometry on the [...] Read more.

The two-phase ejector has gained prominence in heat pump systems as a device that effectively mitigates throttling losses through expansion work recovery. This investigation employs three-dimensional computational fluid dynamics (CFD) simulations to analyze the parametric effects of the mixing channel geometry on the entrainment characteristics in an R410A ejector. After validating the model according to the experimental data, the parameter analysis was carried out, and four key geometric parameters were changed within a certain range: the nozzle exit position (NXP = 13–19 mm), the pre-mixing channel convergent angle (CA = 20–60°), the diameter ratio (DDR = 5.0–7.1), and the length-to-diameter ratio (LDR = 8.9–12.4). Multi-variable optimization studies revealed optimal geometric configurations at NXP = 17 mm (about 3.5D_mix), CA = 30°, DR = 6.4, and LDR = 11.1, yielding an optimized mass entrainment ratio enhancement of 23.6% compared to baseline designs. This research provides actionable guidelines for the design of high-efficiency ejector components for heat pump applications. Full article

(This article belongs to the Section Process Control and Monitoring)

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22 pages, 3169 KiB

Open AccessArticle

Optimal Process Control for Rotor Speed Recovery and Secondary Frequency Drop Mitigation in Wind Turbine Frequency Regulation

by Liqing Yang, Zhishuai Hu, Zhenzhou Zhao and Yongfeng Ren

Processes 2025, 13(6), 1932; https://doi.org/10.3390/pr13061932 - 18 Jun 2025

Viewed by 64

Abstract

Driven by the demand for low-carbon and sustainable development, power systems are increasingly transitioning toward higher proportions of renewable energy and power-electronic interfaces, leading to a growing requirement for wind turbines to provide inertia support and frequency regulation (FR). Wind turbine kinetic energy-based [...] Read more.

Driven by the demand for low-carbon and sustainable development, power systems are increasingly transitioning toward higher proportions of renewable energy and power-electronic interfaces, leading to a growing requirement for wind turbines to provide inertia support and frequency regulation (FR). Wind turbine kinetic energy-based FR inherently involves a trade-off between rotor speed recovery and grid stability: aggressive acceleration exacerbates the secondary frequency drop (SFD), while suppressing SFD prolongs rotor speed recovery. This study aims to resolve this dynamic coupling conflict and optimize the rotor speed recovery process by employing a segmented rotor speed recovery strategy. Firstly, a detailed wind farm-integrated frequency response model is developed. Leveraging its identified speed recovery dynamics, a five-dimensional rotor speed recovery evaluation framework is established. Subsequently, guided by this evaluation framework, a segmented rotor speed recovery control strategy is designed. Finally, three validation scenarios—a single wind turbine, 10% wind power penetration, and 30% wind power penetration—are constructed to evaluate the proposed strategy. Comparative analysis demonstrates that the proposed segmented rotor speed recovery strategy reduces aerodynamic power recovery time by 28.5% and power disturbance by 47.3% in an operational scenario with 30% wind power penetration, effectively achieving synergistic coordination of recovery acceleration and SFD suppression. Full article

(This article belongs to the Section Process Control and Monitoring)

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42 pages, 6284 KiB

Open AccessReview

Review of Automotive Thermoelectric Generator Structure Design and Optimization for Performance Enhancement

by Yue Wang, Ruochen Wang, Ruiqian Chai, Renkai Ding, Qing Ye, Zeyu Sun, Xiangpeng Meng and Dong Sun

Processes 2025, 13(6), 1931; https://doi.org/10.3390/pr13061931 - 18 Jun 2025

Viewed by 44

Abstract

Thermoelectric generator (TEG) has emerged as a critical technology for automotive exhaust energy recovery, yet there is still a lack of reviews analyzing automotive TEG structure design and optimization methods simultaneously. Therefore, this review consolidates structure design and methods for improving thermoelectric conversion [...] Read more.

Thermoelectric generator (TEG) has emerged as a critical technology for automotive exhaust energy recovery, yet there is still a lack of reviews analyzing automotive TEG structure design and optimization methods simultaneously. Therefore, this review consolidates structure design and methods for improving thermoelectric conversion efficiency, focusing on three core components: thermoelectric module (TEM), heat exchanger (HEX), and heat sink (HSK). For TEM, research and development efforts have primarily centered on material innovation and structural optimization, with segmented, non-segmented, and multi-stage configurations emerging as the three primary structural types. HEX development spans external geometries, including plate, polygonal, and annular designs, and internal enhancements such as fin, heat pipe, metal foam, and baffle to augment heat transfer. HSK leverages active, passive, or hybrid cooling systems, with water-cooling designs prevalent in automotive TEG for cold-side thermal management. Optimization methods encompass theoretical analysis, numerical simulation, experimental testing, and hybrid methods, with strategies devised to balance computational efficiency and accuracy based on system complexity and resource availability. This review provides a systematic framework to guide the design and optimization of automotive TEG. Full article

(This article belongs to the Section Energy Systems)

18 pages, 1628 KiB

Open AccessFeature PaperArticle

A More Environmentally Friendly Method for Pulp Processing Using DES-like Mixtures: Comparison of Physical Properties with Oxygen Bleached Pulp

by Lota Chrvalová, Veronika Jančíková, Ida Skotnicová, Michal Jablonský and Štefan Šutý

Processes 2025, 13(6), 1930; https://doi.org/10.3390/pr13061930 - 18 Jun 2025

Viewed by 68

Abstract

The traditional papermaking process uses petroleum-based additives, which raise environmental concerns. As a result, these concerns have attracted the scientific community to explore green additives by introducing environmentally friendly cellulose modifications as additives to the papermaking process. A promising way to process pulp [...] Read more.

The traditional papermaking process uses petroleum-based additives, which raise environmental concerns. As a result, these concerns have attracted the scientific community to explore green additives by introducing environmentally friendly cellulose modifications as additives to the papermaking process. A promising way to process pulp is the application of deep eutectic solvent-like mixtures, which expand new possibilities for delignification processes. This article aims to characterize the physical properties of pulps modified with deep eutectic solvent-like mixtures and to compare these properties to untreated softwood kraft pulp and pulp obtained after oxygen delignification (commercially available pulp; obtained from Mondi Štětí a.s.). The physical properties (mechanical and optical) of the original pulp and delignified pulps were evaluated based on the degree of beating (Schopper–Riegler degree), zeta potential, water retention value, tensile strength, modulus of elasticity, and whiteness. Technology employing deep eutectic solvent-like mixtures shows great promise for sustainable pulp production; however, its full-scale adoption will require further research focused on process optimization, solvent recovery, and economic cost reduction. Full article

(This article belongs to the Special Issue Circular Economy on Production Processes and Systems Engineering)

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20 pages, 3913 KiB

Open AccessArticle

Thermal Management Design for the Be Target of an Accelerator-Based Boron Neutron Capture Therapy System Using Numerical Simulations with Boiling Heat Transfer Models

by Bo-Jun Lu, Yuh-Ming Ferng, Tzung-Yi Lin, Cheng-Ji Lu and Wei-Lin Chen

Processes 2025, 13(6), 1929; https://doi.org/10.3390/pr13061929 - 18 Jun 2025

Viewed by 98

Abstract

Recently, studies on accelerator-based boron neutron capture therapy (AB-BNCT) systems for cancer treatment have attracted the attention of researchers around the world. A neutron source can be obtained through the impingement of high-intensity proton beams emitted from the accelerator onto the target. This [...] Read more.

Recently, studies on accelerator-based boron neutron capture therapy (AB-BNCT) systems for cancer treatment have attracted the attention of researchers around the world. A neutron source can be obtained through the impingement of high-intensity proton beams emitted from the accelerator onto the target. This process would deposit a large amount of heat within this target. A thermal management system design is needed for AB-BNCT systems to prevent the degradation of the target due to thermal/mechanical loading. However, there are few studies that investigate this topic. In this paper, a cooling channel with a boiling heat transfer mechanism is numerically designed for thermal management in order to remove heat deposited in the Be target of the AB-BNCT system of Heron Neutron Medical Corp. A three-dimensional (3D) CFD methodology with a two-fluid model and an RPI wall boiling model is developed to investigate its availability. Two subcooled boiling experiments from previous works are adopted to validate the present CFD boiling model. This validated model can be confidently applied to assist in thermal management design for the AB-BNCT system. Based on the simulation results under the typical operating conditions of the AB-BNCT system set by Heron Neutron Medical Corp., the present coolant channel employing the boiling heat transfer mechanism can efficiently remove the heat deposited in the Be target, as well as maintain its integrity during long-term operation. In addition, compared with the channel with the single-phase convection traditionally designed for an AB-BNCT system, the boiling heat transfer mechanism can result in a lower peak temperature in the Be target and its corresponding deformation. Full article

(This article belongs to the Special Issue Numerical Simulation of Flow and Heat Transfer Processes)

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24 pages, 6924 KiB

Open AccessArticle

Application of Ulva intestinalis Linnaeus Biomass-Derived Biosorbents for Eco-Friendly Removal of Metal Contaminants from Water

by Alaa M. Younis and Ghada M. Almutairi

Processes 2025, 13(6), 1928; https://doi.org/10.3390/pr13061928 - 18 Jun 2025

Viewed by 102

Abstract

The study examines the biosorption potential of Ulva intestinalis (UI) and calcium oxide-modified Ulva intestinalis (CaO-UI) for the environmentally favorable removal of cadmium (Cd²⁺), nickel (Ni²⁺), and lead (Pb²⁺) from aqueous solutions. This research addresses the critical [...] Read more.

The study examines the biosorption potential of Ulva intestinalis (UI) and calcium oxide-modified Ulva intestinalis (CaO-UI) for the environmentally favorable removal of cadmium (Cd²⁺), nickel (Ni²⁺), and lead (Pb²⁺) from aqueous solutions. This research addresses the critical need for sustainable water treatment solutions by developing a green-synthesized biosorbent that combines renewable biomass with enhanced adsorption properties. The adsorption properties of the biomass were improved by preparing calcium oxide (CaO) using Ulva intestinalis extract by green synthesis. Langmuir, Freundlich, and Temkin isotherms were employed to model the results of adsorption experiments that were conducted under a variety of conditions, such as contact time, biosorbent dose, and initial metal ion concentration. Langmuir (R² = 0.999) and Freundlich (R² = 0.999) models both provided an exceptionally well-fitted model for the adsorption isotherms, suggesting a hybrid mechanism that integrates monolayer chemisorption at CaO-active sites and multilayer adsorption on the heterogeneous algal matrix. Key findings demonstrate that the maximum adsorption capacity (qm) of CaO-UI was substantially higher than that of UI, with values of 571.21 mg/g for Cd²⁺, 665.51 mg/g for Ni²⁺, and 577.87 mg/g for Pb²⁺, respectively, in comparison to 432.47 mg/g, 335.75 mg/g, and 446.65 mg/g for UI. The adsorption process was dominated by pseudo-second-order (PSO) chemisorption, as evidenced by kinetic studies (R² = 0.949–0.993). CaO-UI exhibited substantially higher rate constants (k₂ = 9.00–10.15 mg/mg·min) than raw UI (k₂ = 4.72–5.71 mg/mg·min). The green synthesis of calcium oxide has resulted in an increase in surface area, porosity, and functional group density, which is responsible for the enhanced performance of CaO-UI. The adsorption efficacy of Pb²⁺ was the highest, followed by Cd²⁺ and Ni²⁺, which was indicative of the differences in metal ion affinity and hydration energy. These results underscore the potential of CaO-UI as a biosorbent that is both cost-effective and sustainable for the removal of heavy metals in wastewater treatment applications. Full article

(This article belongs to the Special Issue Natural Low-Cost Adsorbents in Water Purification Processes)

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21 pages, 2249 KiB

Open AccessArticle

Multifractal Characterization of Full-Scale Pore Structure in Middle-High-Rank Coal Reservoirs: Implications for Permeability Modeling in Western Guizhou–Eastern Yunnan Basin

by Fangkai Quan, Yanhui Zhang, Wei Lu, Chongtao Wei, Xuguang Dai and Zhengyuan Qin

Processes 2025, 13(6), 1927; https://doi.org/10.3390/pr13061927 - 18 Jun 2025

Viewed by 157

Abstract

This study presents a comprehensive multifractal characterization of full-scale pore structures in middle- to high-rank coal reservoirs from the Western Guizhou–Eastern Yunnan Basin and establishes a permeability prediction model integrating fractal heterogeneity and pore throat parameters. Eight coal samples were analyzed using mercury [...] Read more.

This study presents a comprehensive multifractal characterization of full-scale pore structures in middle- to high-rank coal reservoirs from the Western Guizhou–Eastern Yunnan Basin and establishes a permeability prediction model integrating fractal heterogeneity and pore throat parameters. Eight coal samples were analyzed using mercury intrusion porosimetry (MIP), low-pressure gas adsorption (N₂/CO₂), and multifractal theory to quantify multiscale pore heterogeneity and its implications for fluid transport. Results reveal weak correlations (R² < 0.39) between conventional petrophysical parameters (ash yield, volatile matter, porosity) and permeability, underscoring the inadequacy of bulk properties in predicting flow behavior. Full-scale pore characterization identified distinct pore architecture regimes: Laochang block coals exhibit microporous dominance (0.45–0.55 nm) with CO₂ adsorption capacities 78% higher than Tucheng samples, while Tucheng coals display enhanced seepage pore development (100–5000 nm), yielding 2.5× greater stage pore volumes. Multifractal analysis demonstrated significant heterogeneity (Δα = 0.98–1.82), with Laochang samples showing superior pore uniformity (D₁ = 0.86 vs. 0.82) but inferior connectivity (D₂ = 0.69 vs. 0.71). A novel permeability model was developed through multivariate regression, integrating the heterogeneity index (Δα) and effective pore throat diameter (D₁₀), achieving exceptional predictive accuracy. The strong negative correlation between Δα and permeability (R = −0.93) highlights how pore complexity governs flow resistance, while D₁₀’s positive influence (R = 0.72) emphasizes throat size control on fluid migration. This work provides a paradigm shift in coal reservoir evaluation, demonstrating that multiscale fractal heterogeneity, rather than conventional bulk properties, dictates permeability in anisotropic coal systems. The model offers critical insights for optimizing hydraulic fracturing and enhanced coalbed methane recovery in structurally heterogeneous basins. Full article

(This article belongs to the Special Issue Comprehensive Evaluation and Utilization of Coal Measure Mineral Resources)

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15 pages, 1136 KiB

Open AccessArticle

Risk Management in Nuclear Power Plant Configuration: Practices and Applications in China

by Yongyue Chu, Kunze Yang, Yan Yi, Sijuan Chen and Ming Yang

Processes 2025, 13(6), 1926; https://doi.org/10.3390/pr13061926 - 18 Jun 2025

Viewed by 99

Abstract

This paper explores the application and evolution of Configuration Risk Management (CRM) systems in Chinese nuclear power plants, focusing on their alignment with the National Nuclear Safety Administration (NNSA)’s technical policies. It examines how CRM integrates risk management action matrices, risk limits, and [...] Read more.

This paper explores the application and evolution of Configuration Risk Management (CRM) systems in Chinese nuclear power plants, focusing on their alignment with the National Nuclear Safety Administration (NNSA)’s technical policies. It examines how CRM integrates risk management action matrices, risk limits, and monitoring tools to manage risks effectively across both second-generation plants with a higher baseline Core Damage Frequency (CDF) and third-generation plants with a lower baseline CDF. The study highlights the significant advancements in CRM system development, including the improvement of risk monitoring tools and the establishment of standardized technical guidelines, and underscores the critical role of ongoing regulatory support and CRM system enhancement to ensure the safe and sustainable operation of nuclear power plants in China, offering valuable insights for future nuclear safety management. Full article

(This article belongs to the Special Issue Process Safety Technology for Nuclear Reactors and Power Plants)

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13 pages, 4110 KiB

Open AccessFeature PaperArticle

Development of a Hybrid Heat Exchange Air Conditioner with a Ground Heat Exchanger Placed Downstream from the Outdoor Unit Heat Exchanger

by Shumpei Funatani, Yusaku Tsukamoto and Koji Toriyama

Processes 2025, 13(6), 1925; https://doi.org/10.3390/pr13061925 - 18 Jun 2025

Viewed by 196

Abstract

This study presents an innovative hybrid geothermal air conditioning system that combines conventional air-based heat exchange with ground heat exchange technology. The system features a ground heat exchanger placed downstream from the outdoor unit heat exchanger, requiring minimal modifications to conventional air conditioners [...] Read more.

This study presents an innovative hybrid geothermal air conditioning system that combines conventional air-based heat exchange with ground heat exchange technology. The system features a ground heat exchanger placed downstream from the outdoor unit heat exchanger, requiring minimal modifications to conventional air conditioners through the addition of bypass flow paths and a four-way valve. This design ensures that the ground heat exchanger consistently operates after the outdoor unit heat exchanger in both cooling and heating modes. The researchers evaluated the proposed system’s performance through both computational simulation (1D-CAE) and experimental testing. Simulation results demonstrated significant efficiency improvements, with the hybrid system achieving a coefficient of performance (COP) of 4.51 compared to just 1.24 for conventional air conditioners under extreme temperature conditions (38 °C). The experimental validation with a shallow-buried (20 cm) ground heat exchanger confirmed an approximately 20% COP improvement across various ambient temperatures. The main advantages of this hybrid system over conventional geothermal systems include reduced installation costs due to shorter borehole lengths, separate air conditioning units and underground piping, and compatibility with existing control systems. The design addresses skilled labor shortages while enabling large-scale demonstration operations with minimal initial investment. Future work will focus on optimizing the burial depth and conducting long-term durability testing to advance practical implementation. Full article

(This article belongs to the Special Issue Energy Storage Systems and Thermal Management)

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14 pages, 6331 KiB

Open AccessArticle

Kinetics of Acid Leaching of Niobium from Man-Made Raw Materials of Titanium Magnesium Production: Experimental Research and Modelling

by Azamat Yessengaziyev, Azamat Toishybek, Arailym Mukangaliyeva, Bagdat Altaibayev, Kenzhegali Smailov, Albina Yersaiynova and Nurgaly Abdyldayev

Processes 2025, 13(6), 1924; https://doi.org/10.3390/pr13061924 - 17 Jun 2025

Viewed by 93

Abstract

Niobium, with its unique properties, plays a key role in high-tech industries, but its recovery from secondary sources remains poorly studied. The kinetics of niobium leaching from niobium-containing middlings obtained via the water treatment of dust chamber sublimations of titanium chlorinators is considered [...] Read more.

Niobium, with its unique properties, plays a key role in high-tech industries, but its recovery from secondary sources remains poorly studied. The kinetics of niobium leaching from niobium-containing middlings obtained via the water treatment of dust chamber sublimations of titanium chlorinators is considered in this study. The leaching process was conducted using a fluoride–sulphuric acid solution. The experiments were performed at 25–90 °C in agitation mode. Kinetic data were analysed using compression-core and mixed-control models, which made it possible to establish the limiting stages of the process. A mixed mechanism, including a chemical reaction on the surface and diffusion through a layer of products with an activation energy of 30.05 kJ/mol, was established. The niobium recovery degree increased from 35.25 to 93.5% as the temperature increased, highlighting its effect on the process. The insoluble residue, rich in titanium, and the liquid phase with niobium and zirconium have the potential for further processing. The results provide the basis to optimise technologies intended to recover niobium from man-made raw materials, contributing to an increase in resource efficiency. Full article

(This article belongs to the Special Issue Recent Trends in Extractive Metallurgy)

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16 pages, 2170 KiB

Open AccessArticle

The Design of an Intensified Process and Production Plant for Cosmetic Emulsions Using Amazonian Oils

by Laura Scalvenzi, Estela Guardado Yordi, Edgar Wilfrido Santamaría Caño, Ibeth Nina Avilez Tolagasi, Matteo Radice, Reinier Abreu-Naranjo, Lianne León Guardado, Luis Ramón Bravo Sánchez and Amaury Pérez Martínez

Processes 2025, 13(6), 1923; https://doi.org/10.3390/pr13061923 - 17 Jun 2025

Viewed by 58

Abstract

The cosmetic industry in the Ecuadorian Amazon region faces the challenge of competitively integrating locally sourced plant-based raw materials into efficient and sustainable production processes. This study proposes the design of a pilot plant for the production of a cosmetic emulsion (CE), using [...] Read more.

The cosmetic industry in the Ecuadorian Amazon region faces the challenge of competitively integrating locally sourced plant-based raw materials into efficient and sustainable production processes. This study proposes the design of a pilot plant for the production of a cosmetic emulsion (CE), using oils extracted from Morete (Mauritia flexuosa) and Ungurahua (Oenocarpus bataua), with a focus on process intensification to reduce both capital investment and resource consumption. Process design methodologies and computational simulation (SuperPro Designer V10) were applied, along with Systematic Layout Planning (SLP) principles to optimize spatial configuration. The intensified scheme enabled the integration of extraction lines, reducing the number of major equipment units from 12 to 9 and lowering the investment from USD 1,016,000 to USD 719,000. Energy and environmental indicators showed consumption levels of 5.86 kWh and 48.4 kg of water per kg of cream, which are lower than those reported for other natural cosmetics plants. The intensified design achieved a Net Present Value (NPV) of USD 577,000 and a payback period of 3.93 years. Furthermore, solid by-products were valorized through circular economy principles. This approach offers a feasible, viable, and sustainable solution for the utilization of these Amazonian oils in the cosmetic industry. Full article

(This article belongs to the Special Issue 2nd Edition of Innovation in Chemical Plant Design)

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26 pages, 2618 KiB

Open AccessArticle

Steel-Based Gravity Energy Storage: A Two-Stage Planning Approach for Industrial Parks with Renewable Energy Integration

by Qingqi Sun, Yufeng Guo, Wei Xu, Bixi Zhang, Yilin Du and Yifei Liu

Processes 2025, 13(6), 1922; https://doi.org/10.3390/pr13061922 - 17 Jun 2025

Viewed by 65

Abstract

Although the integration of large-scale energy storage with renewable energy can significantly reduce electricity costs for steel enterprises, existing energy storage technologies face challenges such as deployment constraints and high costs, limiting their widespread adoption. This study proposes a gravity energy storage system [...] Read more.

Although the integration of large-scale energy storage with renewable energy can significantly reduce electricity costs for steel enterprises, existing energy storage technologies face challenges such as deployment constraints and high costs, limiting their widespread adoption. This study proposes a gravity energy storage system and its capacity configuration scheme, which utilizes idle steel blocks from industry overcapacity as the energy storage medium to enhance renewable energy integration and lower corporate electricity costs. First, a stackable steel-based gravity energy storage (SGES) structure utilizing idle blocks is designed to reduce investment costs. Second, a gravity energy storage capacity planning model is developed, incorporating economic and structural collaborative optimization to maximize profitability and minimize construction costs. Finally, a Rime and particle swarm optimization (RI-PSO) fusion algorithm is proposed to efficiently solve the optimization problem. The results demonstrate that under equivalent power and capacity conditions, the SGES structure achieves 90.11% lower costs than compressed air energy storage and 59.7% lower costs than electrochemical storage. The proposed algorithm improves convergence accuracy by 21.19% compared to Rime and 4.21% compared to PSO and increases convergence speed by 72.34% compared to Rime. This study provides an effective solution for steel enterprises to reduce costs. Full article

(This article belongs to the Special Issue Modeling, Operation and Control in Renewable Energy Systems)

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30 pages, 6345 KiB

Open AccessArticle

Multimodal Switching Control Strategy for Wide Voltage Range Operation of Three-Phase Dual Active Bridge Converters

by Chenhao Zhao, Chuang Huang, Shaoxu Jiang and Rui Wang

Processes 2025, 13(6), 1921; https://doi.org/10.3390/pr13061921 - 17 Jun 2025

Viewed by 37

Abstract

In recent years, to achieve “dual carbon” goals, increasing the penetration of renewable energy has become a critical approach in China’s power sector. Power electronic converters play a key role in integrating renewable energy into the power system. Among them, the Dual Active [...] Read more.

In recent years, to achieve “dual carbon” goals, increasing the penetration of renewable energy has become a critical approach in China’s power sector. Power electronic converters play a key role in integrating renewable energy into the power system. Among them, the Dual Active Bridge (DAB) DC-DC converter has gained widespread attention due to its merits, such as galvanic isolation, bidirectional power transfer, and soft switching. It has been extensively applied in microgrids, distributed generation, and electric vehicles. However, with the large-scale integration of stochastic renewable sources and uncertain loads into the grid, DAB converters are required to operate over a wider voltage regulation range and under more complex operating conditions. Conventional control strategies often fail to meet these demands due to their limited soft-switching range, restricted optimization capability, and slow dynamic response. To address these issues, this paper proposes a multi-mode switching optimized control strategy for the three-port DAB (3p-DAB) converter. The proposed method aims to broaden the soft-switching range and optimize the operation space, enabling high-power transfer capability while reducing switching and conduction losses. First, to address the issue of the narrow soft-switching range at medium and low power levels, a single-cycle interleaved phase-shift control mode is proposed. Under this control, the three-phase Dual Active Bridge can achieve zero-voltage switching and optimize the minimum current stress, thereby improving the operating efficiency of the converter. Then, in the face of the actual demand for wide voltage regulation of the converter, a standardized global unified minimum current stress optimization scheme based on the virtual phase-shift ratio is proposed. This scheme establishes a unified control structure and a standardized control table, reducing the complexity of the control structure design and the gain expression. Finally, both simulation and experimental results validate the effectiveness and superiority of the proposed multi-mode optimized control strategy. Full article

(This article belongs to the Special Issue Energy Storage Planning, Control, and Dispatch for Grid Dynamic Enhancement)

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20 pages, 5393 KiB

Open AccessArticle

Robust Optimization of Hydraulic Fracturing Design for Oil and Gas Scientists to Develop Shale Oil Resources

by Qiang Lin, Wen Fang, Li Zhang, Qiuhuan Mu, Hui Li, Lizhe Li and Bo Wang

Processes 2025, 13(6), 1920; https://doi.org/10.3390/pr13061920 - 17 Jun 2025

Viewed by 39

Abstract

Shale plays with pre-existing natural fractures can yield significant production when operating horizontal wells with multi-stage hydraulic fracturing (HWMHF). This work proposes a general, robust, and integrated framework for estimating optimal HWMHF design parameters in an unconventional naturally fractured oil reservoir. This work [...] Read more.

Shale plays with pre-existing natural fractures can yield significant production when operating horizontal wells with multi-stage hydraulic fracturing (HWMHF). This work proposes a general, robust, and integrated framework for estimating optimal HWMHF design parameters in an unconventional naturally fractured oil reservoir. This work considers uncertainty in both the distribution of the natural fractures and uncertainty in three geo-mechanical parameters: the internal friction factor, the cohesion coefficient, and the tensile strength. Because a maximum of five design variables is considered, it is appropriate to apply derivative-free algorithms. This work considers versions of the genetic algorithm (GA), particle swarm optimization (PSO), and general pattern search (GPS) algorithms. The forward model consists of two linked software programs: a geo-mechanical simulator and an unconventional shale oil simulator. The two simulators run sequentially during the optimization process without human intervention. The in-house geo-mechanical simulator model provides sufficient computational efficiency so that it is feasible to solve the robust optimization problem. An embedded discrete fracture model (EDFM) is implemented to model large-scale fractures. Two cases strongly verified the feasibility of the framework for the optimization of HWMHF, and the average comprehensive NPV increases by 35% and 102.4%, respectively. By comparison, the pattern search algorithm is more suitable for HWMHF optimization. In this way, oil and gas scientists are contributing to the energy industry more accurately and resolutely. Full article

(This article belongs to the Special Issue Advances in Unconventional Reservoir Development and CO₂ Storage)

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19 pages, 4106 KiB

Open AccessArticle

Cake Moisture Estimation Based on Image Analysis and Regression Model for Controlling the Compression Time of Filter Press in Sludge Dewatering

by Poltak Sandro Rumahorbo, Nobuhiro Yazawa, Hiroki Ito, Jun Sugimoto, Satoshi Kondo, Yoshifumi Okada, Kazuhiko Sato, Warut Timprae and Shinya Watanabe

Processes 2025, 13(6), 1919; https://doi.org/10.3390/pr13061919 - 17 Jun 2025

Viewed by 41

Abstract

This study proposes practical methods for estimating the moisture content of sludge, represented by the cake moisture, in the filter press dewatering process. Because the cake moisture and filtrate volume are difficult to measure directly, the proposed approaches utilize indirectly measurable data, including [...] Read more.

This study proposes practical methods for estimating the moisture content of sludge, represented by the cake moisture, in the filter press dewatering process. Because the cake moisture and filtrate volume are difficult to measure directly, the proposed approaches utilize indirectly measurable data, including drain outlet images and the differential pressure during the compression phase. By analyzing the correlations between these parameters and the cake moisture, estimation models were developed using mathematical approximations. In the image-based approach, image processing techniques were applied to isolate the dewatered region, and the relationship between the pixel count and actual filtrate volume was analyzed to estimate the cake moisture based on the calculated filtrate volume per minute. In the pressure-based approach, two models were proposed: one that directly estimates the cake moisture from the differential pressure, and another that models the relationship among the differential pressure, filtrate volume, and cake moisture. Unlike complex machine learning techniques, the proposed methods employ simple and interpretable mathematical functions, offering both practicality and reliability. Validation using real-world operational data confirmed the accuracy and effectiveness of the proposed approaches. Full article

(This article belongs to the Section Automation Control Systems)

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16 pages, 6234 KiB

Open AccessArticle

Study of the Effects of Differences in Drill Pipe Materials, Drilling Fluids, and Formation Rock Types on the Drag Reduction Capacity of Hydraulic Oscillators

by Xin He, Gonghui Liu, Tian Chen, Jun Li, Wei Wang, Shichang Li and Lincong Wang

Processes 2025, 13(6), 1918; https://doi.org/10.3390/pr13061918 - 17 Jun 2025

Viewed by 28

Abstract

Hydraulic oscillators can effectively reduce the frictional resistance of the horizontal well drilling column and increase mechanical drilling speed, but the influence of geological and operational conditions on the drag reduction performance of these tools has not been fully studied, resulting in the [...] Read more.

Hydraulic oscillators can effectively reduce the frictional resistance of the horizontal well drilling column and increase mechanical drilling speed, but the influence of geological and operational conditions on the drag reduction performance of these tools has not been fully studied, resulting in the selection of hydraulic oscillators still relying mainly on field experience. This study investigates the effects of drill string material, drilling fluid, and tool type on the drag reduction capability of tools. Friction coefficients of two commonly used drill string materials (G105 steel, S135 steel) with three common formation types (sandstone, shale, and limestone) were measured under oil-based and water-based drilling fluid infiltration conditions at different speeds of movement. The experimentally obtained friction coefficients were incorporated into a nonlinear mechanical model of the drill string equipped with a hydraulic oscillator, which was solved using the finite difference method. The results showed that the drill string materials had a limited effect on tool drag reduction capabilities, while rock type and drilling fluid type had a more significant impact. The drag reduction effect of tools in oil-based drilling fluids was better than that of water-based drilling fluids. In shale, the drag reduction effect of tools was better than that in sandstone and limestone. Increasing the amplitude enhanced the drag reduction ability of tools more than increasing the vibration frequency. Increasing the amplitude and frequency of the tool in an oil-based drilling fluid environment produced a more significant increase in drag reduction than doing the same in a water-based drilling fluid environment. These findings can provide theoretical guidance for the design of output characteristics of hydraulic vibrators and field selection of tools under different drilling conditions. Full article

(This article belongs to the Section Energy Systems)

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