Processes

14 pages, 2313 KiB

Open AccessArticle

Assessment of the Influence of Erosion Wear on the Design Parameters and Useful Life of the C4-70 Family Centrifugal Fan

by Sandra Arla, Leonardo Goyos and Jose Mier

Processes 2025, 13(5), 1617; https://doi.org/10.3390/pr13051617 - 21 May 2025

Viewed by 236

Abstract

The design and operating regime of centrifugal fans operating with contaminated flows must consider the influence of different geometric parameters and flow dynamics design variables on fan wear. The influence of fan rotation speed and blade angle of attack on the erosion wear [...] Read more.

The design and operating regime of centrifugal fans operating with contaminated flows must consider the influence of different geometric parameters and flow dynamics design variables on fan wear. The influence of fan rotation speed and blade angle of attack on the erosion wear they may experience when moving fluids contaminated with solid particles is especially relevant. A method is proposed for performing experimental tests that emulate centrifugal fans using a slurry bucket installation, at tangential velocities of 2, 4, and 6 m/s and fluid incidence angles of 16, 22, and 28 degrees. An equation for cumulative wear is found, in which the independent variables incidence angle and linear velocity have a linear and quadratic influence, respectively. It can be specified that when the fan operates at revolutions between 814 and 815 rpm, for a tangential speed of 2 m/s and a flow rate of 20.16 m³/h, an accumulated wear of 1.3124 mg/g is recorded, caused by the impact of solid particles transported by the flow that could impact the surface of the blade when the angle is 22°24′. Full article

(This article belongs to the Special Issue Motor Drive Systems: Control Technology, Fault Diagnosis and Fault Tolerance)

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12 pages, 2176 KiB

Open AccessArticle

Edge-Side Cross-Area State Synchronization Method Adapted to Multiple Delay-Sensitive Services

by Yi Zhou, Li Li, Chang Wang and Lin Yang

Processes 2025, 13(5), 1616; https://doi.org/10.3390/pr13051616 - 21 May 2025

Viewed by 205

Abstract

With the integration of high proportions of new energy and high proportions of power electronic devices, the spatial–temporal correlation scale of emerging distribution business has experienced a sudden increase, and the demand for inter-distribution area collaboration is increasing steadily. Currently, distribution systems heavily [...] Read more.

With the integration of high proportions of new energy and high proportions of power electronic devices, the spatial–temporal correlation scale of emerging distribution business has experienced a sudden increase, and the demand for inter-distribution area collaboration is increasing steadily. Currently, distribution systems heavily rely on cloud master stations to facilitate the state synchronization process across feeders for such business. However, this approach struggles to adapt to the diverse delay-sensitive characteristics anticipated in future large-scale integrations. Therefore, a novel edge-side state synchronization method for cross-feeder operations in distribution systems tailored to diverse delay-sensitive services is proposed. Firstly, the traditional integrated hierarchical vertical network structure is evolved to construct “edge–cloud–edge” and “edge–edge” dual data transmission channels for inter-distribution area nodes. Secondly, considering the unique characteristics of each channel, their expected synchronization delays for differentiated services are calculated. An optimization problem is then formulated with the objective of maximizing the minimum expected synchronization delay redundancy rate. Finally, an iterative variable weighting method is designed to solve this optimization problem. Simulation analysis shows that the proposed algorithm can better adapt to the high-concurrency differentiated inter-distribution area status synchronization demands of diverse time-sensitive businesses, efficiently supporting the flexible, intelligent, and digital transformation of distribution networks. Full article

(This article belongs to the Special Issue Smart Optimization Techniques for Microgrid Management)

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14 pages, 1379 KiB

Open AccessArticle

Efficient Co-Production of Reducing Sugars and Xylo-Oligosaccharides from Waste Wheat Straw Through FeCl₃-Mediated p-Toluene Sulfonic Acid Pretreatment

by Xiuying Hu, Qianqian Gao and Yucai He

Processes 2025, 13(5), 1615; https://doi.org/10.3390/pr13051615 - 21 May 2025

Viewed by 227

Abstract

Waste wheat straw (WS) is a common agricultural waste with a low acquisition cost and a high annual yield, making it a promising feedstock for a biorefinery. In this work, efficient co-production of reducing sugars and xylo-oligosaccharides (XOSs) from WS was realized through [...] Read more.

Waste wheat straw (WS) is a common agricultural waste with a low acquisition cost and a high annual yield, making it a promising feedstock for a biorefinery. In this work, efficient co-production of reducing sugars and xylo-oligosaccharides (XOSs) from WS was realized through FeCl₃-assisted p-toluene sulfonic acid (PTSA) pretreatment. The effects of reaction conditions (PTSA content, FeCl₃ loading, pretreatment duration, and temperature) on lignin and xylan elimination and enzymolysis were analyzed. The results manifested that the enzymolysis of WS substantially elevated from 22.0% to 79.3% through the treatment with FeCl₃-PTSA/water (120 °C, 60 min). The xylan removal and delignification were 79.7% and 66.6%, respectively. XOSs (4.0 g/L) were acquired in the pretreatment liquor. The linear fitting about LogR₀ with enzymolysis, delignification, xylan elimination and XOSs content was investigated to explain the reasons for the elevated enzymolysis and to clarify the comprehensive understanding of WS enzymolysis through the FeCl₃-PTSA/water treatment. In addition, the recycling test of FeCl₃-PTSA/water manifested a good recycling ability for WS treatment, which would reduce the pretreatment cost and enhance the economic benefit. To sum up, FeCl₃-assisted PTSA treatment of biomass for co-production of reducing sugars and XOSs is an alternative method of waste biomass valorization. Full article

(This article belongs to the Section Catalysis Enhanced Processes)

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16 pages, 4135 KiB

Open AccessArticle

Study on Rock Fracture Mechanism Using Well Logging Data and Minimum Energy Consumption Principle: A Case Study of Mesozoic Clastic Rocks in Chengdao–Zhuanghai Area, Jiyang Depression

by Shilong Ma, Shaochun Yang, Yanjia Wu, Dongmou Huang and Yifan Zhang

Processes 2025, 13(5), 1614; https://doi.org/10.3390/pr13051614 - 21 May 2025

Viewed by 208

Abstract

In the Chengdao–Zhuanghai area, there are few core samples of Mesozoic clastic rocks but abundant logging data. It is difficult to establish a fracture model of clastic rocks directly based on core samples and relevant tests. In this study, triaxial compression tests are [...] Read more.

In the Chengdao–Zhuanghai area, there are few core samples of Mesozoic clastic rocks but abundant logging data. It is difficult to establish a fracture model of clastic rocks directly based on core samples and relevant tests. In this study, triaxial compression tests are conducted on Mesozoic clastic rock samples to reveal the failure mechanism of clastic rocks. A statistical model based on logging data is utilized to calculate dynamic rock mechanical parameters, and theoretical relationships between static and dynamic mechanical parameters are derived. A failure model for clastic rocks is established using logging data and the minimum energy consumption principle by applying the principle of minimum energy consumption and adopting the unified energy yield criterion of rocks as the energy consumption constraint. This research study shows that a linear relationship exists between the static and dynamic mechanical parameters of Mesozoic clastic rocks, and the correlation coefficient can reach 85%. The core aspect of clastic rock failure is energy dissipation. As confining pressure increases, more energy must be dissipated during the failure of clastic rocks. Upon failure, the releasable elastic energy accumulated within the clastic rocks clearly reflects the confining pressure effect. A higher initial confining pressure leads to a greater release of elastic energy and results in a more severe failure degree. The developed rock failure model effectively represents the nonlinear mechanical behavior of Mesozoic clastic rocks in the Chengdao–Zhuanghai area under complex stress conditions. It is suitable for investigating the fracture distribution of Mesozoic clastic rocks and addresses the challenge of understanding the failure mechanism of these rocks in the Chengdao–Zhuanghai region. Full article

(This article belongs to the Section Energy Systems)

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33 pages, 1600 KiB

Open AccessFeature PaperReview

Utilisation of Different Types of Glass Waste as Pozzolanic Additive or Aggregate in Construction Materials

by Karolina Bekerė and Jurgita Malaiškienė

Processes 2025, 13(5), 1613; https://doi.org/10.3390/pr13051613 - 21 May 2025

Viewed by 238

Abstract

Unprocessed glass waste is commonly disposed of in landfills, posing a significant environmental threat worldwide due to its non-biodegradable nature and long decomposition period. The volume of this waste continues to increase annually, driven by increasing consumption of electronic and household devices, as [...] Read more.

Unprocessed glass waste is commonly disposed of in landfills, posing a significant environmental threat worldwide due to its non-biodegradable nature and long decomposition period. The volume of this waste continues to increase annually, driven by increasing consumption of electronic and household devices, as well as the growing popularity and end-of-life disposal of solar panels and other glass products. Therefore, to promote the development of the circular economy and the principles of sustainability, it is necessary to address the problem of reusing this waste. This review article examines the chemical and physical properties of various types of glass waste, including window glass, bottles, solar panels, and glass recovered from discarded electronic and household appliances. It was determined that the most promising and applicable reuse, which does not require high energy consumption, could be in the manufacture of concrete, which is the most developed construction material worldwide. Glass waste can be incorporated into concrete in three different particle sizes according to their function: (a) cement-sized particles, used as a partial binder replacement; (b) sand-sized particles, replacing fine aggregate; and (c) coarse aggregate-sized particles, substituting natural coarse aggregate either partially or fully. The article analyses the impact of glass waste on the properties of concrete or binder, presents controversial results, and provides recommendations for future research. In addition, the advantages and challenges of incorporating glass waste in ceramics and asphalt concrete are highlighted. Full article

(This article belongs to the Special Issue Green Chemistry: From Wastes to Value-Added Products (2nd Edition))

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17 pages, 3265 KiB

Open AccessArticle

Influence of Hydrophilic Groups of Surfactants on Their Adsorption States and Wetting Effect on Coal Dust

by Chaohang Xu, Tongyuan Zhang, Sijing Wang, Jian Gan and Hetang Wang

Processes 2025, 13(5), 1612; https://doi.org/10.3390/pr13051612 - 21 May 2025

Viewed by 183

Abstract

Surfactants are often used in the process of coal dust suppression, and the wetting effect is greatly affected by the surfactant hydrophilic group structures. In order to explore the influence of hydrophilic groups of surfactants on their adsorption states and wetting effect on [...] Read more.

Surfactants are often used in the process of coal dust suppression, and the wetting effect is greatly affected by the surfactant hydrophilic group structures. In order to explore the influence of hydrophilic groups of surfactants on their adsorption states and wetting effect on coal dust, three surfactants with similar hydrophilic groups were selected, namely, anionic surfactant sodium dodecyl sulfate (SDS), anionic-nonionic surfactant alkyl ether sulfate (AES), and nonionic surfactant alkyl polyoxyethylene ether-3 (AEO-3). To assess surfactant efficiency, surface tension, wetting time, infrared spectra, and wetting heat were analyzed. These parameters provide insights into molecular adsorption, interfacial behavior, and energy changes during wetting. The different adsorption states of surfactants on the coal dust surface due to EO and SO₄²⁻ hydrophilic groups were analyzed. Results show that both anionic surfactant SDS and nonionic surfactant AEO-3 form the monolayer adsorption structure on the coal dust surface. Due to the electrostatic repulsion of SO₄²⁻ groups, the adsorption density of SDS is lower than that of AEO-3, which results in the higher wetting heat of AEO-3 compared to SDS. In addition, the EO groups without electrostatic repulsion make AEO-3 molecules more tightly adsorbed at the air–liquid interface, causing the minimal surface tension. Therefore, the wetting time of AEO-3 is shorter than that of SDS. The anionic-nonionic surfactant AES has both EO and SO₄²⁻ groups. Because the EO groups in the inner surfactant adsorption layer can attract Na⁺ ions to distribute around them, the free AES molecules further form the outer adsorption layer under the electrostatic attraction between SO₄²⁻ groups and Na⁺ ions. The double-layer adsorption structure causes the hydrophobic groups of the outer AES molecules to face outward, the hydrophobic sites on the coal dust surface are not completely transformed into hydrophilic sites. Although AES exhibits the highest adsorption density, it has the lowest wetting heat and the longest wetting time. The research results can provide theoretical guidance for the selection of suitable surfactants for coal dust suppression. Full article

(This article belongs to the Special Issue Green Particle Technologies: Processes and Applications)

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Graphical abstract

23 pages, 2285 KiB

Open AccessArticle

AI-Driven Maintenance Optimisation for Natural Gas Liquid Pumps in the Oil and Gas Industry: A Digital Tool Approach

by Abdulmajeed Almuraia, Feiyang He and Muhammad Khan

Processes 2025, 13(5), 1611; https://doi.org/10.3390/pr13051611 - 21 May 2025

Viewed by 272

Abstract

Natural Gas Liquid (NGL) pumps are critical assets in oil and gas operations, where unplanned failures can result in substantial production losses. Traditional maintenance approaches, often based on static schedules and expert judgement, are inadequate for optimising both availability and cost. This study [...] Read more.

Natural Gas Liquid (NGL) pumps are critical assets in oil and gas operations, where unplanned failures can result in substantial production losses. Traditional maintenance approaches, often based on static schedules and expert judgement, are inadequate for optimising both availability and cost. This study proposes a novel Artificial Intelligence (AI)-based methodology and digital tool for optimising NGL pump maintenance using limited historical data and real-time sensor inputs. The approach combines dynamic reliability modelling, component condition assessment, and diagnostic logic within a unified framework. Component-specific maintenance intervals were computed using mean time between failures (MTBFs) estimation and remaining useful life (RUL) prediction based on vibration and leakage data, while fuzzy logic- and rule-based algorithms were employed for condition evaluation and failure diagnoses. The tool was implemented using Microsoft Excel Version 2406 and validated through a case study on pump G221 in a Saudi Aramco facility. The results show that the optimised maintenance routine reduced the total cost by approximately 80% compared to conventional individual scheduling, primarily by consolidating maintenance activities and reducing downtime. Additionally, a structured validation questionnaire completed by 15 industry professionals confirmed the methodology’s technical accuracy, practical usability, and relevance to industrial needs. Over 90% of the experts strongly agreed on the tool’s value in supporting AI-driven maintenance decision-making. The findings demonstrate that the proposed solution offers a practical, cost-effective, and scalable framework for the predictive maintenance of rotating equipment, especially in environments with limited sensory and operational data. It contributes both methodological innovation and validated industrial applicability to the field of maintenance optimisation. Full article

(This article belongs to the Special Issue Application of Artificial Intelligence in Industrial Process Modelling and Optimization)

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27 pages, 6302 KiB

Open AccessArticle

Design of a Novel Transition-Based Deadlock Recovery Policy for Flexible Manufacturing Systems

by Wen-Yi Chuang, Ching-Yun Tseng, Kuang-Hsiung Tan and Yen-Liang Pan

Processes 2025, 13(5), 1610; https://doi.org/10.3390/pr13051610 - 21 May 2025

Viewed by 219

Abstract

In the domain of application of PN theory, the system deadlock problem of a flexible manufacturing system (FMS) is a thorny problem that needs to be solved urgently. All the research has the same objective of designing optimal controllers with maximal permissiveness and [...] Read more.

In the domain of application of PN theory, the system deadlock problem of a flexible manufacturing system (FMS) is a thorny problem that needs to be solved urgently. All the research has the same objective of designing optimal controllers with maximal permissiveness and liveness. Plenty of the past literature used deadlock prevention as the main control strategy that is implemented by control places. However, these methods usually forbid undesirable system states from being reached, while reducing the system’s liveness. This study employed the resource flow graph (RFG)-based method to achieve a deadlock recovery policy that can maintain maximal permissiveness by adding control transitions (CTs). Also, we improved the current definition of RFG and developed a systematic approach for generating the corresponding RFG, which is based on flow mirroring pair (FMP) functions and the software Graphviz 12.2.1. Furthermore, this study proposed an automatic method that forms DOT script for generating Graphviz images, which is convincingly demonstrated in this study to enhance the execution efficiency and recognition of circular waiting situations. Full article

(This article belongs to the Special Issue Industry 4.0 and Industry 5.0: Simulators and Algorithms in Manufacturing Processes and Systems)

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18 pages, 3622 KiB

Open AccessArticle

Utilization of an Amide-Based Collector in Fluorite Flotation

by Peng Liu, Yuhui Tian, Chun Zhang, Mengjie Tian and Wei Sun

Processes 2025, 13(5), 1609; https://doi.org/10.3390/pr13051609 - 21 May 2025

Viewed by 138

Abstract

Fluorite is commonly associated with calcite and other Ca-bearing gangue minerals in nature. Fluorite and its associated Ca-bearing gangue minerals share similar surface active sites involving Ca²⁺ ions and have comparable surface properties, making their flotation separation challenging. Traditional fatty acid collectors, [...] Read more.

Fluorite is commonly associated with calcite and other Ca-bearing gangue minerals in nature. Fluorite and its associated Ca-bearing gangue minerals share similar surface active sites involving Ca²⁺ ions and have comparable surface properties, making their flotation separation challenging. Traditional fatty acid collectors, such as oleic acid, suffer from poor selectivity. This study investigates the use of N-hydroxy-N-phenyloctanamide (HPOA) as a novel collector for fluorite, with the goal of improving its flotation separation from Ca-bearing gangue minerals. Flotation tests demonstrate that HPOA provides superior selectivity compared to oleic acid in separating fluorite from calcite. Research on the adsorption capacity of HPOA on mineral surfaces shows that, under equivalent testing conditions, HPOA shows greater adsorption amounts on fluorite than on calcite. As a result, HPOA has a superior collecting capacity in fluorite flotation. First-principles calculations reveal that HPOA adsorbs on the fluorite surface by forming chemical bonds with Ca²⁺ ions via its hydroxyl and carbonyl groups. Moreover, HPOA exhibits strong adsorption on fluorite surface, as indicated by more significant shifts in the binding energies of Ca²⁺ ions on fluorite compared to calcite after HPOA adsorption. This study highlights the potential of amide-based collectors to improve fluorite flotation and offers valuable insights into the development of more selective flotation reagents. Full article

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

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13 pages, 5662 KiB

Open AccessArticle

Characterization of the Lower Limit of CH₄ Explosion in Different Atmospheres over a Wide Temperature Range

by Jida Zhang, Qinghe Bao, Junhui Yang, Haibin Guan, Zhongcheng Ma, Bari Wulan and Sheng Li

Processes 2025, 13(5), 1608; https://doi.org/10.3390/pr13051608 - 21 May 2025

Viewed by 156

Abstract

This study conducted systematic experimental research on methane safety issues in industrial production environments, with a particular focus on the impacts of high-temperature conditions and complex atmospheres on methane explosion characteristics. The research team designed and constructed a dedicated combustible gas explosion experimental [...] Read more.

This study conducted systematic experimental research on methane safety issues in industrial production environments, with a particular focus on the impacts of high-temperature conditions and complex atmospheres on methane explosion characteristics. The research team designed and constructed a dedicated combustible gas explosion experimental setup, performing in-depth experimental analyses across a broad temperature range from 25 °C to 600 °C. The results demonstrate that elevated temperatures significantly reduced the methane’s lower explosion limit (LEL), with the LEL decreasing to approximately 40% of its room-temperature value at 600 °C. The investigation systematically examined the influence mechanisms of common industrial atmospheric components, including carbon dioxide (CO₂), ammonia (NH₃), oxygen (O₂), and water vapor (H₂O) on methane explosion behavior. Key findings reveal that CO₂ exhibited notable suppression effects, increasing methane’s LEL by approximately 15% per 10% increment in CO₂ concentration. NH₃ demonstrated dual mechanisms, promoting methane explosions at low concentrations (<5%) while inhibiting them at higher concentrations. Increased O₂ concentration significantly expanded the methane’s explosive range, with the LEL decreasing by about 22% when O₂ concentration increased from 21% to 30%. Water vapor manifested differentiated impacts depending on temperature regimes, primarily elevating LEL through dilution effects below 200 °C while reducing LEL via radical reaction promotion above 400 °C. Furthermore, this study reveals synergistic coupling effects between temperature and gas components—for instance, CO₂’s suppression efficacy weakened under high temperatures, whereas NH₃’s promotion effect intensified. These discoveries provide scientific foundations for formulating industrial safety standards, designing explosion-proof equipment, and conducting risk assessments in production processes. Full article

(This article belongs to the Special Issue Research on Catalyst and Reaction Kinetics in Fossil Fuel Refining, Biofuels, Green Hydrogen and Petrochemicals)

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21 pages, 4153 KiB

Open AccessArticle

Study on Risk Mitigation Measures for Atmospheric Storage Tank of Acrylic Acid Due to Abnormal Weather Conditions

by Gabgi Jeong, Minseo Nam, Jaeyoung Kim and Byung-Tae Yoo

Processes 2025, 13(5), 1607; https://doi.org/10.3390/pr13051607 - 21 May 2025

Viewed by 177

Abstract

This study analyzes the risks posed by high-temperature summer conditions to atmospheric storage tanks containing acrylic acid and proposes mitigation measures. Recent increases in heat waves and tropical nights have led to an increase in the temperatures of acrylic acid storage tanks. This [...] Read more.

This study analyzes the risks posed by high-temperature summer conditions to atmospheric storage tanks containing acrylic acid and proposes mitigation measures. Recent increases in heat waves and tropical nights have led to an increase in the temperatures of acrylic acid storage tanks. This temperature increase results in higher vapor pressure and promotes spontaneous polymerization, thereby increasing the risk of explosions in atmospheric storage tanks. Hazard and operability (HAZOP) analysis identified explosions due to pressure buildup as a major risk scenario. To mitigate this risk, a spray-tower system was introduced through a layer of protection analysis (LOPA), which effectively reduced the hazards associated with atmospheric storage tanks. Additionally, the removal of flame-arrester replacement operations not only achieves economic benefits, such as reduced replacement costs and labor time, but also enhances safety by eliminating worker exposure to hazardous chemicals. These findings have significant implications for improving safety at industrial sites and highlight the potential economic benefits of preventing chemical accidents. Full article

(This article belongs to the Special Issue Risk Assessment and System Safety in the Process Industry)

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20 pages, 2317 KiB

Open AccessArticle

Thermal Characterization of Structured Porous Materials and Phase Change Composites for Heat Sink Applications

by Abhishek Agarwal, Michel Kalenga Wa Kalenga and Masengo Ilunga

Processes 2025, 13(5), 1606; https://doi.org/10.3390/pr13051606 - 21 May 2025

Viewed by 214

Abstract

Heat sinks are commonly used in electronic devices to dissipate heat from electronic circuits. Phase change materials (PCMs) offer a viable solution for storing thermal energy during peak loads, helping to delay temperature spikes and maintain the heat sink within safe operating limits. [...] Read more.

Heat sinks are commonly used in electronic devices to dissipate heat from electronic circuits. Phase change materials (PCMs) offer a viable solution for storing thermal energy during peak loads, helping to delay temperature spikes and maintain the heat sink within safe operating limits. The objective of the current study is to evaluate the energy storage and thermal characteristics of the PCMs used in the heat sink. The heat sink comprises a structured porous material (SPM), and the PCMs used in the analysis are Paraffin wax and Erythritol. The thermal analysis conducted on the heat sink composed of SPMs integrated with PCMs enabled the determination of thermal characteristics. The thermal characteristics evaluated from FEA analysis have shown superior heat absorption properties of Erythritol as compared to Paraffin wax during the initial phases. At 50 s after the simulation, the heat absorbed by Erythritol is 89% higher than Paraffin wax, whereas at higher stages, Paraffin wax exhibited higher heat absorption characteristics. At higher time intervals, i.e., 250 s after running the simulation, the Paraffin wax exhibited 49% higher heat absorption capacity as compared to Erythritol. This behavior of both PCM materials can be attributed to different specific heat capacities and latent heat of fusion at different temperatures. The higher thermal conductivity of Erythritol enables it to absorb higher heat initially, which makes it highly effective for short-duration thermal applications. The Paraffin wax has a higher latent heat of fusion and, therefore, stores more thermal energy for prolonged periods, which makes it suitable for applications demanding sustained thermal management. The study findings have suggested that for applications demanding rapid heat absorption, the Erythritol PCM is the best option, whereas the Paraffin wax is suited for applications demanding a longer duration of heat storage. Full article

(This article belongs to the Special Issue High-Temperature Behavior of Polymers and Composites)

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27 pages, 5967 KiB

Open AccessArticle

Accuracy-Enhanced Multi-Variable LSTM-Based Sensorless Temperature Estimation for Marine Lithium-Ion Batteries Using Real Operational Data for an ORC–ESS

by Bom-Yi Lim, Chan Roh, Seung-Taek Lim and Hyeon-Ju Kim

Processes 2025, 13(5), 1605; https://doi.org/10.3390/pr13051605 - 21 May 2025

Viewed by 195

Abstract

Driven by increasingly stringent carbon emission regulations from the International Maritime Organization (IMO), the maritime industry increasingly requires eco-friendly power systems and enhanced energy efficiency. Lithium-ion batteries, a core component of these systems, necessitate precise temperature management to ensure safety, performance, and longevity, [...] Read more.

Driven by increasingly stringent carbon emission regulations from the International Maritime Organization (IMO), the maritime industry increasingly requires eco-friendly power systems and enhanced energy efficiency. Lithium-ion batteries, a core component of these systems, necessitate precise temperature management to ensure safety, performance, and longevity, especially under high-temperature conditions owing to the inherent risk of thermal runaway. This study proposes a sensorless temperature estimation method using a long short-term memory network. Using key parameters, including state of charge, voltage, current, C-rate, and depth of discharge, a MATLAB-based analysis program was developed to model battery dynamics. The proposed method enables real-time internal temperature estimation without physical sensors, demonstrating improved accuracy via data-driven learning. Operational data from the training vessel Hannara were used to develop an integrated organic Rankine cycle–energy storage system model, analyze factors influencing battery temperature, and inform optimized battery operation strategies. The results highlight the potential of the proposed method to enhance the safety and efficiency of shipboard battery systems, thereby contributing to the achievement of the IMO’s carbon reduction goals. Full article

(This article belongs to the Special Issue Energy Storage and Conversion: Next-Generation Battery Technology)

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21 pages, 1996 KiB

Open AccessArticle

Comparative Analysis of Sulfuric Acid Alkylation Technologies Based on a Reaction Kinetic Model

by Wenbin Zhang and Hongbo Jiang

Processes 2025, 13(5), 1604; https://doi.org/10.3390/pr13051604 - 21 May 2025

Viewed by 254

Abstract

As a core component of transportation fuels, clean gasoline plays a vital role in environmental protection. Alkylate, with its nearly zero sulfur, aromatic, and olefin contents, coupled with its superior research octane number, serves as an ideal blending component for clean gasoline. This [...] Read more.

As a core component of transportation fuels, clean gasoline plays a vital role in environmental protection. Alkylate, with its nearly zero sulfur, aromatic, and olefin contents, coupled with its superior research octane number, serves as an ideal blending component for clean gasoline. This study established a kinetic model for sulfuric-acid-catalyzed isobutane–butene alkylation based on the carbocation reaction mechanism, incorporating 20 lumped components and 37 reaction pathways. Reactor models were developed to reflect the design characteristics of STRATCO and SINOALKY technologies. The model parameters were estimated using industrial operational data via the non-linear least-squares method. The validation results demonstrated excellent agreement with industrial values, showing average relative deviation rates of 1.72% (STRATCO) and 1.73% (SINOALKY) for C₈ product prediction. A prediction analysis revealed that selectivity and alkylate octane number of C₈ exhibit positive correlations with the isobutane-to-olefin ratio, acid-to-hydrocarbon ratio, and space–time relationship. It was also found that the internal circulation in the STRATCO technology enables thorough contact between the acid and hydrocarbon phases, while the multi-stage feeding in the SINOALKY technology maintains a favorable isobutane-to-olefin ratio. Both features are conducive to the alkylation reaction, enhancing the selectivity and octane number of C₈. These trends align with the intrinsic reaction principles of sulfuric-acid-catalyzed alkylation systems, providing theoretical guidance for alkylate production optimization. Full article

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

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18 pages, 6058 KiB

Open AccessArticle

Fe²⁺-Coupled Organic-Substrate-Enhanced Nitrogen Removal in Two-Stage Anammox Biofilm Reactors

by Yingchun Bao, Qilong Ge, Siyuan Li, Xiaowei Wang, Xuwen Zheng and Zhenguo Chen

Processes 2025, 13(5), 1603; https://doi.org/10.3390/pr13051603 - 21 May 2025

Viewed by 142

Abstract

Anammox is a novel and energy-efficient biological nitrogen removal technology. Enhancing its performance in treating low-strength nitrogen wastewater is essential for expanding its practical applications. In response to challenges such as low nitrogen removal efficiency (NRE), poor operational stability, limited environmental resistance, and [...] Read more.

Anammox is a novel and energy-efficient biological nitrogen removal technology. Enhancing its performance in treating low-strength nitrogen wastewater is essential for expanding its practical applications. In response to challenges such as low nitrogen removal efficiency (NRE), poor operational stability, limited environmental resistance, and the interference of organic compounds commonly found in real wastewater, this study developed a two-stage upflow anammox biofilm reactor system (R1 and R2) enhanced by an Fe²⁺-coupled organic substrate strategy for deep nitrogen removal under low-nitrogen conditions. Results showed that sodium acetate at a chemical oxygen demand (COD) concentration of 40 mg/L provided the greatest enhancement to anammox activity, achieving an average total nitrogen removal efficiency (NRE) of 90.02%. However, the reactor performance was significantly inhibited under higher COD conditions (e.g., COD = 60 mg/L). Under an influent Fe²⁺ concentration of 10 mg/L, the reactors’ NRE increased and then decreased as the COD concentration rose from 0 to 100 mg/L, resulting in the highest efficiency being achieved at an average NRE of 94.11%, observed under 10 mg/L Fe²⁺ coupled with 60 mg/L of COD in the two-stage anammox system. Scanning electron microscopy revealed that the co-addition of Fe²⁺ and organic substrates led to the formation of granular protrusions and pores on the sludge surface, which favored the structural stability of the biomass. At a COD level of 40 mg/L, the contents of extracellular polymeric substances and heme c in anammox biofilm were significantly higher compared to the addition of 10 mg/L Fe²⁺ alone, whereas excessive COD inhibited both indicators. These findings suggest that moderate levels of Fe²⁺ coupled with organic matter can promote anammox activity for deep nitrogen removal, while excessive organics have inhibitory effects. This study provides theoretical support for enhancing nitrogen removal from low-strength wastewater using Fe²⁺ and organic-substrate-assisted anammox processes. Full article

(This article belongs to the Special Issue Research on Water Pollution Control and Remediation Technology)

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13 pages, 1888 KiB

Open AccessArticle

Effects of Different Cooking Parameters on Various Quality Criteria, Lipid Oxidation, Mineral Composition, and Free Amino Acid Profile of Chicken Breast

by Adem Savaş

Processes 2025, 13(5), 1602; https://doi.org/10.3390/pr13051602 - 21 May 2025

Viewed by 232

Abstract

In this study, the effects of chicken breast meat samples cooked in the oven at different temperatures (180, 200, and 220 °C) and times (16, 24, and 32 min) on various quality parameters, lipid oxidation, free amino acid profile, and mineral contents were [...] Read more.

In this study, the effects of chicken breast meat samples cooked in the oven at different temperatures (180, 200, and 220 °C) and times (16, 24, and 32 min) on various quality parameters, lipid oxidation, free amino acid profile, and mineral contents were investigated. Chicken breast samples were also analyzed in terms of several qualitative properties (pH, TBARS, cooking loss, lightness, redness, and yellowness). Both cooking temperature and cooking time affected the qualitative properties. It was determined that the mineral contents of the samples were affected by cooking time and temperature. The mineral content of the samples varied between 1.47 mg kg⁻¹ and 1700.46 mg kg⁻¹. In addition, the analysis of mineral content revealed that the order of mineral abundance in chicken samples was K > Na > Ca > Mg > Zn > Cu. In terms of free amino acid profile, it was determined that essential amino acids methionine (70.71–156.67 mg g⁻¹) and phenylalanine (29.41–44.41 mg g⁻¹), and non-essential amino acids alanine (66.29–141.11 mg g⁻¹), glutamate (76.64–104.39 mg g⁻¹), and glycine (35.03–56.18 mg g⁻¹) contents were the highest. It was determined that the free amino acid content of the samples varied between 1.71 and 156.67 mg g⁻¹. In addition, it was found that the pH, TBARS, cooking loss, lightness, redness, and yellowness parameters were significantly affected (p < 0.01). Consequently, it was found that the cooking temperature and duration significantly influenced the nutritional composition of chicken breast meat. Cooking at 180 °C for 16 min was identified as the optimal condition for minimizing lipid oxidation and maximizing mineral content. Full article

(This article belongs to the Special Issue Advances in Extraction and Characterization of Functional Properties of Bioactive Compounds Obtained from Food Processing)

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17 pages, 3935 KiB

Open AccessArticle

Optimization and Engineering Application of In-Seam Borehole Predrainage Technology for Coalbed Methane Based on Response Surface Methodology

by Yanhui Li, Qian Liu, Chuanjie Zhu and Yue’e Wu

Processes 2025, 13(5), 1601; https://doi.org/10.3390/pr13051601 - 21 May 2025

Viewed by 155

Abstract

To advance the optimization of engineering parameters in in-seam borehole predrainage technology, this study developed a comprehensive analytical framework integrating theoretical modeling, numerical simulation, and field validation. Taking Pingdingshan Tian’an Coal Mine No. 1 as a practical case study, we established a gas-bearing [...] Read more.

To advance the optimization of engineering parameters in in-seam borehole predrainage technology, this study developed a comprehensive analytical framework integrating theoretical modeling, numerical simulation, and field validation. Taking Pingdingshan Tian’an Coal Mine No. 1 as a practical case study, we established a gas-bearing coal seam drainage model based on fluid–solid coupling theory. A multifactor optimization scheme was implemented using response surface methodology (RSM) complemented by an evaluation system focusing on the gas extraction efficiency coefficient (K). Numerical simulations through COMSOL Multiphysics 6.0 enabled detailed investigation of single-factor influences and multifactor coupling effects, ultimately identifying field-verified optimal parameters. Key discoveries include the following: (1) Spatiotemporal evolution patterns of gas drainage compliance zones showing stabilized interborehole pressure gradients and enhanced regional connectivity after 300-day extraction; (2) a parameter sensitivity hierarchy for K-value defined as drainage duration (primary) > borehole spacing > borehole diameter > extraction negative pressure; (3) an optimized configuration (4.5 m spacing, 113 mm diameter, 18 kPa pressure) achieving a 54.2% pressure reduction with a 0.98 efficiency coefficient. Field data demonstrated only 2.1% average deviation from model predictions, validating the methodology’s effectiveness for gas control parameter optimization in coal mining operations. Full article

(This article belongs to the Special Issue Unconventional Energy, Clean Energy and Carbon Sequestration: Progress in Technology)

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16 pages, 11809 KiB

Open AccessArticle

Multi-Layer Filter Material with a Superoleophobic Pore Size Gradient for the Coalescence Separation of Surfactant-Stabilized Oil-in-Water Emulsions

by Xingdong Wu, Ying Wang, Chengzhi Li, Lang Liu, Xiaowei Li and Cheng Chang

Processes 2025, 13(5), 1600; https://doi.org/10.3390/pr13051600 - 21 May 2025

Viewed by 198

Abstract

The performance of oil–water coalescence separation elements currently fails to meet the increasing demands of the oily wastewater treatment industry. To address this challenge, a series of fiber coalescing filters were developed through an underwater superoleophobic modification process using a simple impregnation technique. [...] Read more.

The performance of oil–water coalescence separation elements currently fails to meet the increasing demands of the oily wastewater treatment industry. To address this challenge, a series of fiber coalescing filters were developed through an underwater superoleophobic modification process using a simple impregnation technique. The effect of varying surface wettability on the separation efficiency of oil-in-water (O/W) emulsions stabilized with surfactants was investigated. The results demonstrate that, after undergoing underwater superoleophobic modification, the separation efficiency of the fiber filter material improved by 33.9%, the pressure drop was reduced by 46.1%, and the steady-state quality factor increased by 83.3%. Building upon these findings, an oil-repellent pore size gradient structure was introduced for the coalescence separation of surfactant-stabilized oil-in-water emulsions. This structure exhibited outstanding characteristics, including a low pressure drop and a high-quality factor. Furthermore, when processing emulsions stabilized with surfactants such as OP-10 (nonionic), CTAB (cationic), and SDS (anionic), the structure maintained high separation efficiencies of 93.6%, 96.4%, and 97.2%, respectively, after 10 cycles. Finally, based on experimental data and theoretical analysis, a separation mechanism for oil–water coalescence using superoleophobic pore size gradient filtration materials is proposed. This structure demonstrates significant potential for widespread application in liquid–liquid separation technologies. Full article

(This article belongs to the Special Issue Multiphase Flow Process and Separation Technology)

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17 pages, 5532 KiB

Open AccessArticle

Effect of Mechanical Pressure on Li Metal Deposition Characteristics and Thermal Stability

by Mengyan Xu, Lin Hao, Yiqiang Zhao and Huiqun Fu

Processes 2025, 13(5), 1599; https://doi.org/10.3390/pr13051599 - 21 May 2025

Viewed by 143

Abstract

Pressure significantly influences lithium (Li) deposition behavior. Although previous studies investigating the influence of pressure on Li deposition have often overlooked the impact of mechanical spacer pressure within the cell, this work specifically focuses on this detail. In this study, we explored the [...] Read more.

Pressure significantly influences lithium (Li) deposition behavior. Although previous studies investigating the influence of pressure on Li deposition have often overlooked the impact of mechanical spacer pressure within the cell, this work specifically focuses on this detail. In this study, we explored the effects of mechanical spacer pressure on the electrochemical properties, deposition morphology, solid–electrolyte interphase (SEI), and thermal stability of Li metal deposition, using spacer pressure as a variable in a small-sized electrode half-cell. The experimental results demonstrate that higher spacer pressure positively enhances Li deposition performance across multiple metrics. However, the beneficial effects of higher spacer pressure decrease with increasing deposition capacity. Specifically, at a low deposition capacity (1 mAh/cm²), a higher spacer pressure facilitates Li metal deposition by promoting SEI stabilization, enabling easier deposition, reducing impedance, and enhancing thermal stability. Conversely, at a high deposition capacity (4 mAh/cm²), the spacer pressure does not significantly improve the aforementioned properties. This study combines the morphology of deposited Li with electrochemical and thermal stability assessments, providing valuable research methods and results for evaluating the effects of external pressure on Li metal deposition. Full article

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

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16 pages, 8449 KiB

Open AccessArticle

6-DoF Grasp Detection Method Based on Vision Language Guidance

by Xixing Li, Jiahao Chen, Rui Wu and Tao Liu

Processes 2025, 13(5), 1598; https://doi.org/10.3390/pr13051598 - 21 May 2025

Viewed by 192

Abstract

The interactive grasp of robots can grasp the corresponding objects according to the user’s choice. Most interactive grasp methods based on deep learning comprise visual language and grasp detection models. However, in existing methods, the trainability and generalization ability of the visual language [...] Read more.

The interactive grasp of robots can grasp the corresponding objects according to the user’s choice. Most interactive grasp methods based on deep learning comprise visual language and grasp detection models. However, in existing methods, the trainability and generalization ability of the visual language model is weak, and the robot cannot cope well with grasping small target objects. Therefore, this paper proposes a 6-DoF grasp detection method guided by visual language, which converts text instructions and RGBD images of the scene to be grasped into inputs and outputs for the 6-DoF grasp posture of the object corresponding to the text instructions. In order to improve the trainability and feature extraction ability of the visual language model, a multi-head attention mechanism combined with hybrid normalization is designed. At the same time, a local attention mechanism is introduced into the grasp detection model to enhance the global and local information interaction ability of point cloud data, thereby improving the grasping ability of the grasp detection model for small target objects. The method proposed in this paper first uses the improved visual language model to predict the plane position information of the target object, then uses the improved grasp detection model to predict all the graspable postures in the scene, and finally uses the plane position information to filter out the graspable postures of the target object. The visual language model and grasp detection model proposed in this paper have achieved excellent performance in various scenarios of public datasets while ensuring a specific generalization ability. In addition, we also conducted real grasp experiments, and the 6-DoF grasp detection method based on visual language guidance proposed in this paper achieved a grasp success rate of 95%. Full article

(This article belongs to the Special Issue Transfer Learning Methods in Equipment Reliability Management)

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14 pages, 506 KiB

Open AccessArticle

Valorization of Grape Seed Cake by Subcritical Water Extraction

by Marko V. Malićanin, Jaroslava Švarc-Gajić, Steva M. Lević, Vladislav A. Rac, Ana S. Salević-Jelić, Mirjana B. Pešić, Danijel D. Milinčić, Diana Pasarin and Vesna M. Rakić

Processes 2025, 13(5), 1597; https://doi.org/10.3390/pr13051597 - 20 May 2025

Viewed by 210

Abstract

Agricultural waste originating from the wine industry presents an environmental and economic issue. Grape seeds, a major constituent of grape pomace, are only partially valorized through oil extraction. The cake remaining after oil production is rich in valuable bioactive compounds. In this study, [...] Read more.

Agricultural waste originating from the wine industry presents an environmental and economic issue. Grape seeds, a major constituent of grape pomace, are only partially valorized through oil extraction. The cake remaining after oil production is rich in valuable bioactive compounds. In this study, an advanced extraction technique, which utilizes subcritical water, was employed for bioactive compound recovery from defatted grape seed cakes. Extraction was performed in a nitrogen atmosphere (10 bar) at 130 °C and 170 °C. The extracts were characterized in terms of the total polyphenols, flavonoids, proteins and antioxidant activity. Detailed polyphenol profiles were determined using UHPLC Q-ToF MS analysis. Quantification of the individual sugars was performed by HPLC. The amino acid profile was determined using ion chromatography. The yield of phenolic acids was found to be higher at 170 °C (883 vs. 557 mg/100 g at 130 °C), while the flavonoid content was favored at 130 °C (596 vs. 185 mg/100 g at 170 °C). The total protein, essential amino acid and xylo-oligosaccharide content was higher at 170 °C. The obtained results show that the use of water as the extraction solvent in subcritical conditions is a promising technique for the environmentally friendly valorization of grape seed cakes and biowaste in general. Full article

(This article belongs to the Special Issue New Advances in Green Extraction Technology for Natural Products)

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21 pages, 1725 KiB

Open AccessArticle

Impact of Ultrasound Pretreatment and Temperature on Drying Kinetics and Quality Characteristics of Blood Orange Slices: Comparison with Different Drying Methods

by Damla Yilmaz, Zeynep Hazal Tekin-Cakmak and Salih Karasu

Processes 2025, 13(5), 1596; https://doi.org/10.3390/pr13051596 - 20 May 2025

Viewed by 232

Abstract

This study aimed to investigate the impact of ultrasonic pretreatment vacuum drying (UAVD) and temperature on drying kinetics and qualitative attributes of blood oranges in comparison to several drying methods: hot air drying (HAD), vacuum drying (VD), and freeze drying (FD). The drying [...] Read more.

This study aimed to investigate the impact of ultrasonic pretreatment vacuum drying (UAVD) and temperature on drying kinetics and qualitative attributes of blood oranges in comparison to several drying methods: hot air drying (HAD), vacuum drying (VD), and freeze drying (FD). The drying kinetics and modeling, total phenolic content (TPC), antioxidant capability (assessed using DPPH and ABTS tests), individual phenolic profiles, vitamin C concentration, and color factors were meticulously examined. Drying times were recorded as 22.5 h, 12.5 h, and 9 h for HAD; 11.5 h, 9.5 h, and 8.5 h for VD; and 10 h, 8.5 h, and 7.5 h for UAVD at 50, 60, and 70 °C, respectively. The HAD, VD, and UAVD procedures were conducted at 50, 60, and 70 °C, resulting in reduced drying periods with increasing temperature. The integration of ultrasound markedly lowered drying durations. Eleven thin-layer drying models were utilized to recreate the drying process precisely. The D_eff values of the HAD, VD, and UAVD dried samples varied from 9.08 × 10⁻⁶ to 2.82 × 10⁻⁵ m²/s, from 2.60 × 10⁻⁵ to 2.96 × 10⁻⁵ m²/s, and from 2.20 × 10⁻⁵ to 2.99 × 10⁻⁵, respectively. Among the desiccated blood orange slices, the greatest total phenolic content (TPC) was observed in freeze-dried samples (131.27 mg GAE/100 g), followed by those dried using ultrasonic-assisted vacuum drying (UAVD) at 50 °C (128.77 mg GAE/g DM). Dried blood orange slices had a vitamin C content of 29.79 to 49.01 mg/100. The drying process substantially impacted the color parameters L*, a*, and b*. These findings highlight the efficacy of ultrasound-assisted drying in decreasing drying duration while improving the retention of bioactive components in blood orange slices. Full article

(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing, 2nd Edition)

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15 pages, 2980 KiB

Open AccessArticle

Bandgap Prediction of Silicon Oxide Materials for Electric Furnace Refractories Based on Explainable Machine Learning

by Xin Zhao, Yanqing Wu, Jinmei Yang, Xuan Zhao and Yang Han

Processes 2025, 13(5), 1595; https://doi.org/10.3390/pr13051595 - 20 May 2025

Viewed by 211

Abstract

An interpretable machine learning framework was constructed to predict the bandgap of silicon oxide materials used for electric furnace refractories. Among seven machine learning models compared, the AdaBoost ensemble model performed the best with an R² of 0.80 and MAE of 0.5, [...] Read more.

An interpretable machine learning framework was constructed to predict the bandgap of silicon oxide materials used for electric furnace refractories. Among seven machine learning models compared, the AdaBoost ensemble model performed the best with an R² of 0.80 and MAE of 0.5, indicating high accuracy. Breaking through the traditional limitation of directly correlating features such as the conduction-band minimum (CBM) and valence-band maximum (VBM), this study utilized SHapley Additive exPlanations (SHAP) analysis to uncover deeper relationships between critical features like ‘energy above hull’, ‘num of unique magnetic sites’, and ‘formation energy per atom ‘ with the bandgap. These features significantly influence the thermal stability and erosion resistance of the material. This research provides a theoretical basis for optimizing the performance of silicon oxide materials and green metallurgical processes, thereby promoting sustainable development in the steel industry. Full article

(This article belongs to the Special Issue Green Metallurgical Process and Technology)

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22 pages, 5036 KiB

Open AccessArticle

Particle Motion and Gas–Solid Heat Exchange Enhancement in Rotary Drums with Aligned/Separated Flight

by Yewei He, Dianyu E and Zeyi Jiang

Processes 2025, 13(5), 1594; https://doi.org/10.3390/pr13051594 - 20 May 2025

Viewed by 232

Abstract

In a waste heat recovery rotary drum with flights (RDF), particle lifting enhances gas–solid contact but also increases the complexity of particle motion in both radial and axial directions. In this study, a long rotary drum model applicable to both aligned and separated [...] Read more.

In a waste heat recovery rotary drum with flights (RDF), particle lifting enhances gas–solid contact but also increases the complexity of particle motion in both radial and axial directions. In this study, a long rotary drum model applicable to both aligned and separated flights was developed. The discrete element method was employed to investigate the effects of the inclination angle, feed rate, and rotation speed on particle dynamics and heat exchange performance. Additionally, a gas–solid heat exchange model was formulated to quantitatively assess the system’s heat recovery efficiency, power recovery, and power consumption. The results indicated that particle motion exhibited greater randomness along the axial direction, and the proposed long-drum model effectively captured the key parameters influencing particle dynamics. The heat exchange capacity of the RDF was closely related to the filling degree, which was found to be most sensitive to the inclination angle. Although the separated flight formed a spiral-shaped particle curtain and significantly enhanced the uniformity of the particle distribution, its heat exchange capacity was lower than that of the aligned flight, and it increased the construction cost by more than 30%. Under all operating conditions, the total system power consumption remained below 20% of the recovered power output. Full article

(This article belongs to the Section Particle Processes)

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18 pages, 3699 KiB

Open AccessArticle

A New Method for Calculating the Setting Stress of Downhole Packer’s Inner Sleeve

by Zixuan Tian, Sizhu Zhou, Wanquan Deng, Ning Li, Xiang Li, Yun Zeng and Shujie Liu

Processes 2025, 13(5), 1593; https://doi.org/10.3390/pr13051593 - 20 May 2025

Viewed by 183

Abstract

There is no analytical solution to the stress, strain and displacement changes in the inner sleeve of the downhole packer during service. In this paper, the inner sleeve structure is simplified based on the shell theory model, and the geometric equation and physical [...] Read more.

There is no analytical solution to the stress, strain and displacement changes in the inner sleeve of the downhole packer during service. In this paper, the inner sleeve structure is simplified based on the shell theory model, and the geometric equation and physical equation suitable for the inner-sleeve structure are established based on the control differential equation of the cylindrical shell derived by Flügge. Finally, the analytical solution calculation program of the radial displacement, and strain and stress value of each node of the cylindrical shell under the external load condition is compiled by using MATLAB R2024a software. The analytical solution is compared with the numerical solution of each parameter under the same conditions, and the root mean square error between the numerical solution and the analytical solution is evaluated. The results show that the analytical formulas of the stress, strain and displacement of the inner sleeve structure of the downhole packer established in this paper can accurately obtain the above parameters. The root mean square errors between the analytical formulas and the numerical solutions are 0.083, 0.074 and 0.086, indicating that the fitting degree between the two is good, which verifies the effectiveness of the theoretical model based on the shell to describe the stress state of the inner sleeve. The model also accurately reflects the partial stress and strain law of the inner sleeve of the downhole packer to a certain extent. This study provides theoretical support for the design optimization of the inner sleeve of a pipeline packer, and also provides some guidance for the study of the stress state of its inner sleeve. Full article

(This article belongs to the Section Energy Systems)

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19 pages, 2957 KiB

Open AccessArticle

Spent Coffee Ground-Based Materials Evaluated by Methylene Blue Removal

by Andrea Mariela Araya-Sibaja, Tamara Quesada-Soto, José Roberto Vega-Baudrit, Mirtha Navarro-Hoyos, Johnny Valverde-Cerdas and Luis Guillermo Romero-Esquivel

Processes 2025, 13(5), 1592; https://doi.org/10.3390/pr13051592 - 20 May 2025

Viewed by 523

Abstract

Spent coffee grounds (SCG) are produced in large quantities during coffee brewing, contributing to environmental concerns. Additionally, cationic dyes from textile, paper, and leather wastewater pose a major pollution issue. This study explores SCG as an adsorbent for methylene blue (MB) dye. A [...] Read more.

Spent coffee grounds (SCG) are produced in large quantities during coffee brewing, contributing to environmental concerns. Additionally, cationic dyes from textile, paper, and leather wastewater pose a major pollution issue. This study explores SCG as an adsorbent for methylene blue (MB) dye. A novel comparison of SCG cleaning methods with warm water, accelerated solvent extraction (ASE), supercritical fluid extraction (SFE), and ultrasound-induced cavitation (US) is presented. In addition, the chemical modifications of SCG using acetylation, acid (HNO₃), and base (KOH) treatment that have not been reported before are presented. ATR-FTIR confirmed the inclusion of functional groups, for example, the nitro group in SCG treated with HNO₃, and an increase in carboxylic groups in the samples treated with KOH and HNO₃. SEM analysis revealed a consistent porous texture across samples, with SCG-SFE, SCG-US, and SCG-HNO₃ showing smaller pores, and SCG-ASE displaying elongated cavities. Adsorption isotherm tests followed the Freundlich and Langmuir models, indicating favorable adsorption. The Langmuir maximum adsorption capacity (q_max) varied among cleaning methods from 65.69 mg/g (warm water) to 93.32 mg/g (SFE). In contrast, in base- and acid-treated SCG, a three- to four-fold increase in adsorption capacity was observed, with q_max values of 171.60 mg/g and 270.64 mg/g, respectively. These findings demonstrate that SCG washed with warm water and chemically treated achieves adsorption capacities comparable to other biosorbents reported in the literature. Therefore, SCG represents a promising, low-cost, and sustainable material for removing cationic dyes from wastewater, contributing to waste valorization and environmental protection. Full article

(This article belongs to the Section Environmental and Green Processes)

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34 pages, 763 KiB

Open AccessReview

Bio-Based Polyurethane Materials: Technical, Environmental, and Economic Insights

by Piumi Jayalath, Kalyani Ananthakrishnan, Soyeon Jeong, Reshma Panackal Shibu, Mairui Zhang, Deepak Kumar, Chang Geun Yoo, Julia L. Shamshina and Obste Therasme

Processes 2025, 13(5), 1591; https://doi.org/10.3390/pr13051591 - 20 May 2025

Viewed by 577

Abstract

Polyurethane (PU) is widely used due to its attractive properties, but the shift to a low-carbon economy necessitates alternative, renewable feedstocks for its production. This review examines the synthesis, properties, and sustainability of bio-based PU materials, focusing on renewable resources such as lignin, [...] Read more.

Polyurethane (PU) is widely used due to its attractive properties, but the shift to a low-carbon economy necessitates alternative, renewable feedstocks for its production. This review examines the synthesis, properties, and sustainability of bio-based PU materials, focusing on renewable resources such as lignin, vegetable oils, and polysaccharides. It discusses recent advances in bio-based polyols, their incorporation into PU formulations, and the use of bio-fillers like chitin and nanocellulose to improve mechanical, thermal, and biocompatibility properties. Despite promising material performance, challenges related to large-scale production, economic feasibility, and recycling technologies are highlighted. The paper also reviews life cycle assessment (LCA) studies, revealing the complex and context-dependent environmental benefits of bio-based PU materials. These studies indicate that while bio-based PU materials generally reduce greenhouse gas emissions and non-renewable energy use, their environmental performance varies depending on feedstock and formulation. The paper identifies key areas for future research, including improving biorefinery processes, optimizing crosslinker performance, and advancing recycling methods to unlock the full environmental and economic potential of bio-based PU in commercial applications. Full article

(This article belongs to the Special Issue Integrated Biorefineries for Sustainable Production of Biofuel and Bioproducts)

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14 pages, 1557 KiB

Open AccessArticle

Lignin Extracted from Green Coconut Waste Impregnated with Sodium Octanoate for Removal of Cu²⁺ in Aqueous Solution

by Jéssyca E. S. Pereira, Eduardo L. Barros Neto, Lindemberg J. N. Duarte, Ruan L. S. Ferreira, Ricardo P. F. Melo and Paula F. P. Nascimento

Processes 2025, 13(5), 1590; https://doi.org/10.3390/pr13051590 - 20 May 2025

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Abstract

Investigating viable processes for the use of lignocellulosic biomass in clean fuels and high-value-added chemical products is essential for sustainable development. Large amounts of lignin are available every year as by-products of the paper and biorefinery industries, causing a series of problems, particularly [...] Read more.

Investigating viable processes for the use of lignocellulosic biomass in clean fuels and high-value-added chemical products is essential for sustainable development. Large amounts of lignin are available every year as by-products of the paper and biorefinery industries, causing a series of problems, particularly environmental ones. Its structure and composition make lignin compatible with the concept of sustainability, since it can be used to produce new chemical products with high added value. As such, this study aims to extract lignin from green coconut fiber (LIG), with the subsequent impregnation of a sodium-octanoate-based surfactant (LIG-SUR), and determine its applicability as an adsorbent for removing copper ions from synthetic waste. To this end, the green coconut fiber lignocellulosic biomass was initially subjected to alkaline pre-treatment with 2% (w/v) sodium hydroxide in an autoclave. Next, the surface of the lignin was modified by impregnating it with sodium octanoate, synthesized from the reaction of octanoic acid and NaOH. The physical and chemical traits of the lignin were studied before and after surfactant impregnation, as well as after copper ion adsorption. The lignin was analyzed by X-ray fluorescence (XRF), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). The adsorption tests were carried out using lignin pre-treated with surfactant in a batch system, where the effects of pH and adsorbent concentration were investigated. XRF and SEM analyses confirmed surfactant impregnation, with Na₂O partially replaced by CuO after Cu²⁺ adsorption. FTIR analysis revealed shifts in O–H, C–H, C=O, and C=C bands, indicating electrostatic interactions with lignin. Adsorption kinetics followed the pseudo-second-order model, suggesting chemisorption, with equilibrium reached in approximately 10 and 60 min for LIG-SUR and LIG, respectively. The Langmuir model best described the isotherm data, indicating monolayer adsorption. LIG-SUR removed 91.57% of Cu²⁺ and reached a maximum capacity of 30.7 mg·g⁻¹ at 25 °C and a pH of 6. The results of this research showed that pre-treatment with NaOH, followed by impregnation with surfactant, significantly increased the adsorption capacity of copper ions in solution. This technique is a viable and sustainable alternative to the traditional adsorbents used to treat liquid waste. In addition, by using green coconut fiber lignin more efficiently, the research contributes to adding value to this material and strengthening practices in line with the circular economy and environmental preservation. Full article

(This article belongs to the Special Issue Emerging Technologies in Solid Waste Recycling and Reuse)

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24 pages, 4239 KiB

Open AccessArticle

Thermodynamic and Exergetic Evaluation of a Newly Designed CSP Driven Cooling-Desalination Cogeneration System

by Hassan F. Elattar, Abdul Khaliq, Bassam S. Aljohani, Abdullah M. A. Alsharif and Hassanein A. Refaey

Processes 2025, 13(5), 1589; https://doi.org/10.3390/pr13051589 - 20 May 2025

Viewed by 264

Abstract

This investigation attempts to develop a tower solar collector-based system designed for the cogeneration of cooling and desalination. The traditional organic Rankine cycle (ORC) integrated with the ejector refrigeration cycle generates limited power and cooling at a single temperature. Acknowledging their [...] Read more.

This investigation attempts to develop a tower solar collector-based system designed for the cogeneration of cooling and desalination. The traditional organic Rankine cycle (ORC) integrated with the ejector refrigeration cycle generates limited power and cooling at a single temperature. Acknowledging their limitations, our present study uses an organic flash cycle (OFC) supported by solar heat combined with the two-phase ejector cycle and the reverse osmosis (RO) desalination unit. Since the OFC turbine is fed with two extra streams of fluid, therefore, it provides greater power to run the compressor of the ejector and pumps of the RO unit, resulting in the production of cooling at two different temperatures (refrigeration and air conditioning) and a higher mass flow rate of fresh water. A mathematical model is employed to assess the impact of coil curvature ratio, Rib height, and direct normal irradiation (DNI) on the temperature of the collector’s oil outlet. ANSYS-FLUENT conducts numerical simulations through computational fluid dynamics (CFD) analysis. The results indicate an ultimate increase in oil outlet temperature of 45% as the DNI increased from 450 to 1000 W/m² at a curvature ratio of 0.095 when employing the 1st Rib. Further, a steady-state energy and exergy analysis is conducted to evaluate the performance of the proposed cogeneration, with different design parameters like DNI, coil curvature ratio, rib height, and OFC turbine inlet pressure. The energetic and exergetic efficiencies of the cogeneration system at DNI of 800 W/m² are obtained as 16.67% and 6.08%, respectively. Exergetic assessment of the overall system shows that 29.57% is the exergy produced as cooling exergy, and the exergy accompanied by freshwater, 68.13%, is the exergy destroyed, and 2.3% is the exergy loss. The solar collector exhibits the maximum exergy destruction, followed by the ejector and RO pumps. Integrating multiple technologies into a system with solar input enhances efficiency, energy sustainability, and environmental benefits. Full article

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

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17 pages, 1223 KiB

Open AccessArticle

Hierarchical Federated Learning with Hybrid Neural Architectures for Predictive Pollutant Analysis in Advanced Green Analytical Chemistry

by Yingfeng Kuang, Xiaolong Chen and Chun Zhu

Processes 2025, 13(5), 1588; https://doi.org/10.3390/pr13051588 - 20 May 2025

Viewed by 239

Abstract

We propose a hierarchical federated learning (HFL) framework for predictive pollutant analysis in advanced green analytical chemistry (AGAC), addressing the limitations of centralized approaches in scalability and data privacy. The system integrates localized sub-models with hybrid neural architectures, combining LSTM and attention mechanisms [...] Read more.

We propose a hierarchical federated learning (HFL) framework for predictive pollutant analysis in advanced green analytical chemistry (AGAC), addressing the limitations of centralized approaches in scalability and data privacy. The system integrates localized sub-models with hybrid neural architectures, combining LSTM and attention mechanisms to capture temporal dependencies and feature importance in distributed analytical data, while raw measurements remain decentralized. A global aggregator dynamically adjusts model weights based on validation performance and data heterogeneity, ensuring robust adaptation to diverse environmental conditions. The framework interfaces seamlessly with AGAC infrastructure, processing inputs from analytical instruments into standardized sequences and mapping predictions back to pollutant concentrations through calibration curves. Implemented with PyTorch Federated and edge-cloud deployment, the system employs homomorphic encryption for secure data transmission, prioritizing spectral features critical for organic pollutant detection. Our approach achieves superior accuracy and privacy preservation compared to traditional centralized methods, offering a transformative solution for scalable environmental monitoring. The proposed method demonstrates significant potential for real-world applications, particularly in scenarios requiring distributed data collaboration without compromising analytical integrity. Full article

(This article belongs to the Special Issue Advanced Green Analytical Chemistry for Environmental Pollutants Detection)

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