Processes

23 pages, 4740 KiB

Open AccessArticle

On the Fluid Behavior Response Characteristics During Early Stage of CBM Co-Production in Superimposed Pressure Systems: Insights from Experimental Analysis

by Jiewei Ren, Qixian Li, Meichang Zhang, Jiang Xu, Yang Li and Pengbin Yang

Processes 2025, 13(4), 1095; https://doi.org/10.3390/pr13041095 (registering DOI) - 5 Apr 2025

Abstract

The fluid disturbance effect is a significant challenge in CBM (CBM) co-production within superimposed pressure systems in China. To address the unique CBM reservoir of superimposed pressure systems, a CBM co-production experimental apparatus for multi-pressure systems has been independently developed. To comprehensively understand [...] Read more.

The fluid disturbance effect is a significant challenge in CBM (CBM) co-production within superimposed pressure systems in China. To address the unique CBM reservoir of superimposed pressure systems, a CBM co-production experimental apparatus for multi-pressure systems has been independently developed. To comprehensively understand fluid behavior during the early stage of CBM co-production, two sets of experiments were conducted using the self-developed physical simulation test device: one in single-production mode and the other in co-production mode. The dynamic response of reservoir fluids and gas production characteristics were analyzed, and the fluid disturbance mechanism under wellbore fluid confluences was explored. The method adopted in this study addresses the issues of traditional co-production equipment, such as the use of series-parallel core holders, small dimensions, limited monitoring capabilities, single loading methods, and the lack of consideration for wellbore co-production flow disturbance and fluid redistribution in superimposed pressure systems. The following results were obtained: ① A flow disturbance effect emerges when fluids from coal reservoirs with different pressure properties converge and mix in a main wellbore. The pressure inside the four horizontal wells simultaneously reaches 1.45 MPa at t = 0.03 min. ② Based on the fluid disturbance effect, the evolution process of wellbore pressure is categorized into two stages: the confluence disturbance stage and the confluence pressure drop stage. ③ This fluid disturbance effect exacerbates the disparities among coal reservoirs, facilitating fluid exchange between the main wellbore and coal reservoirs through branch wellbores. Under the co-production mode, the instantaneous gas production of the No. 1 coal reservoir reaches its maximum negative value at the moment of production, amounting to −3.85 L/min, indicating that a portion of the fluid from high-pressure coal reservoirs flows back into low-pressure coal reservoirs. ④ A dynamic characterization compatibility method is proposed based on the differences in fluid flow between the single and co-production modes during the early stage of CBM production. For example, at t = 0.1 min, the pressure compatibility coefficients of the No. 1–4 coal reservoirs are 0.72, 0.45, 0.34, and 0.33, respectively. The pressure compatibility and production compatibility coefficients exhibit rapid growth during the early stages, followed by a slight decrease during the middle and later stages. ⑤ The worst compatibility performances are observed during the early stage of CBM co-production, but these performances improve as the co-production time extends. ⑥ Optimizing superimposed pressure systems involves progressive co-production: dynamically introducing coal reservoirs, balancing reservoir pressure, minimizing fluid disturbance, and enhancing recovery efficiency. Full article

(This article belongs to the Special Issue Advances in Coal Processing, Utilization, and Process Safety)

16 pages, 3481 KiB

Open AccessArticle

Chemical–Mechanical Polishing of 4H-SiC Using Multi-Catalyst Synergistic Activation of Potassium Peroxymonosulfate

by Congzheng Li, Mengmeng Shen, Xuelai Li, Yuhan Fu, Yanfang Dong, Binghai Lyu and Julong Yuan

Processes 2025, 13(4), 1094; https://doi.org/10.3390/pr13041094 (registering DOI) - 5 Apr 2025

Abstract

This study optimized the proportions of synergistic catalysts to efficiently activate potassium peroxymonosulfate (Oxone), generate more reactive oxygen species, and accelerate the chemical oxidation of silicon carbide (4H-SiC) wafers during chemical–mechanical polishing (CMP) for an improved material removal rate (MRR) and surface quality. [...] Read more.

This study optimized the proportions of synergistic catalysts to efficiently activate potassium peroxymonosulfate (Oxone), generate more reactive oxygen species, and accelerate the chemical oxidation of silicon carbide (4H-SiC) wafers during chemical–mechanical polishing (CMP) for an improved material removal rate (MRR) and surface quality. The Oxone was activated using ultraviolet (UV) catalysis with a photocatalyst (TiO₂) and transition metal (Fe₃O₄) to enhance the oxidation capacity of the polishing slurry through the production of strong oxidizing sulfate radicals (). First, the effects of the TiO₂, Fe₃O₄, and Oxone concentrations on the MRR were studied by conducting multiple single-factor experiments. Next, 4H-SiC wafers were polished using different catalyst combinations to verify the synergistic activation of Oxone by multiple catalysts. Finally, the roughnesses, physical features, and elemental compositions of the wafer surfaces were observed before and after polishing. The results showed that CMP with a TiO₂ concentration of 0.15 wt%, Fe₃O₄ concentration of 0.75 wt%, and Oxone concentration of 48 mM decreased the wafer surface roughness from Sa 134 to 8.251 nm and achieved a maximum MRR of 2360 nm/h, which is significantly higher than that associated with traditional CMP methods. The surface of a 4H-SiC wafer polished using CMP with the optimal catalytic system was extremely smooth with no scratches and exhibited many oxides that reduced its hardness. In summary, the proposed UV-TiO₂-Fe₃O₄-Oxone composite catalytic system for 4H-SiC CMP exhibited significant synergistic enhancements and demonstrated excellent surface quality, indicating considerable potential for the polishing of hard materials. Full article

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

21 pages, 3353 KiB

Open AccessFeature PaperArticle

Surrogate Modeling of Hydrogen-Enriched Combustion Using Autoencoder-Based Dimensionality Reduction

by Lanfei Zhang, Xu Chu, Siyu Ding, Mingshuo Zhou, Chenxu Ni and Xingjian Wang

Processes 2025, 13(4), 1093; https://doi.org/10.3390/pr13041093 (registering DOI) - 5 Apr 2025

Abstract

Deep learning-based surrogate models have received wide attention for efficient and cost-effective predictions of fluid flows and combustion, while their hyperparameter settings often lack generalizable guidelines. This study examines two different types of surrogate models, convolutional autoencoder (CAE)-based reduced order models (ROMs) and [...] Read more.

Deep learning-based surrogate models have received wide attention for efficient and cost-effective predictions of fluid flows and combustion, while their hyperparameter settings often lack generalizable guidelines. This study examines two different types of surrogate models, convolutional autoencoder (CAE)-based reduced order models (ROMs) and fully connected autoencoder (FCAE)-based ROMs, for emulating hydrogen-enriched combustion from a triple-coaxial nozzle jet. The performances of these ROMs are discussed in detail, with an emphasis on key hyperparameters, including the number of network layers in the encoder (l), latent vector dimensionality (dim), and convolutional stride (s). The results indicate that a larger l is essential for capturing features in strongly nonlinear flowfields, whereas a smaller l is more effective for less nonlinear distributions, as additional layers may cause overfitting. Specifically, when employing CAE-based ROMs to predict the spatial distribution for H₂() with weak nonlinearity, the reconstruction absolute average relative deviation (AARD) from the two-layer model was marginally higher than that of three- and four-layer models, whereas the prediction AARD was approximately 5% lower. A smaller dim yields better performance in weakly nonlinear flowfields but may increase local errors in some cases due to excessive feature compression. A CAE-based ROM with a dim = 10 achieved a notably lower AARD of 4.01% for prediction. A smaller s may enhance the spatial resolution yet raise computational costs. Under identical hyperparameters, the CAE-based ROM outperformed the FCAE-based ROM in both cost-effectiveness and accuracy, achieving a 35 times faster training speed and lower absolute average relative deviation in prediction. These findings provide important guidelines for hyperparameter selection in training autoencoder (AE)-based ROMs for hydrogen-enriched combustion and other similar engineering design problems. Full article

(This article belongs to the Special Issue Modeling, Simulation and Control of Industrial Processes)

15 pages, 3549 KiB

Open AccessArticle

Rapid Determination of Thiourea Concentration in Copper Electrolyte

by Liqing Chen, Xiaofeng Yuan, Yulong Li, Zhenqian Zhang, Yangtao Xu, Wenqian Zhou and Yi Wang

Processes 2025, 13(4), 1092; https://doi.org/10.3390/pr13041092 (registering DOI) - 5 Apr 2025

Abstract

Due to the characteristics of high salt and high acidity of the electrolyte and the chemical reaction between thiourea (Tu) and metal ions, it is still a problem to quickly and accurately detect Tu concentration in copper electrolyte. An improved spectrophotometric method has [...] Read more.

Due to the characteristics of high salt and high acidity of the electrolyte and the chemical reaction between thiourea (Tu) and metal ions, it is still a problem to quickly and accurately detect Tu concentration in copper electrolyte. An improved spectrophotometric method has been proposed by simplifying the extraction steps of the traditional extraction–spectrophotometry and reducing the dosage of extractant and buffer. The improved method, with a favorable R² of 0.9991, great precision of 1.67% and excellent spiked recovery of 102.19%, was not affected by the presence of gelatin and copper ions. Moreover, based on the spectrophotometry, a colorimetric method for rapid detection of Tu concentration in copper electrolyte was proposed. Using the standard color card produced enabled the expeditious determination of the concentration range of Tu in copper electrolyte. Since the gray value of the standard color card is linearly related to the Tu concentration, it is feasible to determine the Tu concentration by measuring the gray value of the test strip, and its accuracy was verified by spectrophotometry. The colorimetric method has satisfactory results in industrial practice. This study provides a novel approach for the rapid detection of Tu concentration in the copper electrolysis industry. Full article

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

► Show Figures

Figure 1

16 pages, 2500 KiB

Open AccessArticle

Quantitative Prediction Method for Post-Fracturing Productivity of Oil–Water Two-Phase Flow in Low-Saturation Reservoirs

by Huijian Wen, Xueying Li, Xuchao He, Qiang Sui, Bo Xing and Chao Wang

Processes 2025, 13(4), 1091; https://doi.org/10.3390/pr13041091 (registering DOI) - 5 Apr 2025

Abstract

The fluid properties of low-saturation reservoirs (LSRs) produced after fracturing are complex and diverse, which makes it difficult to predict the post-fracturing productivity of oil–water two-phase flow and results in a low prediction accuracy. Therefore, based on elliptical seepage theory and nonlinear steady-state [...] Read more.

The fluid properties of low-saturation reservoirs (LSRs) produced after fracturing are complex and diverse, which makes it difficult to predict the post-fracturing productivity of oil–water two-phase flow and results in a low prediction accuracy. Therefore, based on elliptical seepage theory and nonlinear steady-state seepage formula, a new method for predicting the post-fracturing productivity (PFP) of oil–water two-phase flow in vertical wells in LSRs after fracturing is proposed in this paper. The Li Kewen model is preferred for accurately calculating oil–water relative permeability. Based on the elliptical fracture morphology, a quantitative prediction model for the PFP of oil–water two-phase flow is established. This model incorporates a starting pressure gradient (SPG) to depict the non-Darcy flow seepage law in low-permeability reservoirs. Hydraulic fracturing fracture length, width and permeability are obtained using logging curves and fracturing data, and this model can be applied to the quantitative prediction of PFP of oil–water two-phase flow in LSRs. The research results show that the conformity rate of oil production is 77.5%, and that of water production is 73.2%, with an improvement of over 15% in the interpretation conformity rate. Compared with actual well test productivity, the mean absolute error of the oil productivity prediction is 3.51 t/d, and the mean absolute error of the water productivity prediction is 12.37 t/d, which meet the requirements of field productivity quantitative evaluation, indicating the effectiveness of this quantitative prediction method for predicting the PFP of oil–water two-phase flow. Full article

(This article belongs to the Section Energy Systems)

► Show Figures

Figure 1

16 pages, 1968 KiB

Open AccessArticle

Drilling and Completion Condition Recognition Algorithm Based on CNN-GNN-LSTM Neural Networks and Applications

by Gang Wei, Xiyue Yang, Mingming Li, Song Gao, Xiang Wan, Changfang Ji, Xiaoyong Gao and Chaodong Tan

Processes 2025, 13(4), 1090; https://doi.org/10.3390/pr13041090 (registering DOI) - 5 Apr 2025

Abstract

Drilling and completion condition identification is of great significance in improving operational efficiency, reducing safety risks and optimizing resource utilization. However, traditional methods rely on experts’ experience and rules and have low recognition accuracy and poor robustness when facing dynamic working condition changes. [...] Read more.

Drilling and completion condition identification is of great significance in improving operational efficiency, reducing safety risks and optimizing resource utilization. However, traditional methods rely on experts’ experience and rules and have low recognition accuracy and poor robustness when facing dynamic working condition changes. In recent years, deep learning technology has shown great potential in the field of time series data analysis and multimodal data fusion. In this paper, we propose a hybrid deep learning model (CNN-GNN-LSTM) based on a convolutional neural network (CNN), graph neural network (GNN) and long short-term memory network (LSTM). The model extracts the local spatial features of multi-sensors via a CNN module to reduce the noise interference; models the nonlinear dependency between sensors via a GNN module to capture the complex interaction relationship; and mines the long- and short-term time dependencies via an LSTM module to accurately identify the dynamic change and transition process of the working conditions. This significantly improves the classification accuracy under dynamic changes in multi-conditions. This study compares the performance of four models: a CNN, LSTM, CNN-LSTM, and CNN-GNN-LSTM. The results show that the CNN-GNN-LSTM outperforms the other models in key metrics such as the classification accuracy, recall, F1 score, etc., and is more robust to noise interference and changes in complex working conditions. This study verifies the advantages of the hybrid model in multi-sensor complex scenarios and provides technical support for the intelligent development of drilling and completion condition recognition. Full article

(This article belongs to the Section Energy Systems)

► Show Figures

Figure 1

14 pages, 2713 KiB

Open AccessArticle

Measuring Variable Discharge Under Partially Full Pipe Flow

by Vasiliki Koutsospyrou, Graham Sander, Ashraf El-Hamalawi, Duncan Wallace and Martin Croft

Processes 2025, 13(4), 1089; https://doi.org/10.3390/pr13041089 (registering DOI) - 4 Apr 2025

Abstract

Accurately measuring the discharge in partially full pipe flow is both difficult and demanding. In this regard, a new meter sensor using microwave technology has been evaluated for determining partially full pipe discharge across a range of flow depths. A range of experiments [...] Read more.

Accurately measuring the discharge in partially full pipe flow is both difficult and demanding. In this regard, a new meter sensor using microwave technology has been evaluated for determining partially full pipe discharge across a range of flow depths. A range of experiments with smooth PVC pipes of two different pipe diameters (101.6 and 152.4 mm) at two different pipe slopes (1° and 2°) were carried out under turbulent (Reynolds numbers = (0.27–3.25) × 10⁵) and supercritical flows with Froude numbers F_r in the range of 1.5 ≤ F_r ≤ 3.6. Our results showed that when combining the microwave sensor readings with either the Chezy equation or Manning’s law, reliable discharge predictions were found compared to the measured discharge across all experiments. The range of R² values obtained from the plots of predicted versus measured discharge were all greater than 97%, indicating an accuracy allowing the meter to be used in commercial applications. Full article

(This article belongs to the Special Issue Model Based, Data Driven Identification and Control for Developing Intelligent and Smart Processes and Systems)

► Show Figures

Figure 1

26 pages, 3426 KiB

Open AccessArticle

Experimental Study of Dye Degradation in a Single-Jet Cavitation System

by Julius-Alexander Nöpel, Jochen Fröhlich and Frank Rüdiger

Processes 2025, 13(4), 1088; https://doi.org/10.3390/pr13041088 - 4 Apr 2025

Abstract

Fluid mechanical conditions are crucial for cavitation formation, and significantly influence chemical reactivity. This study investigates process conditions such as pressure, degassing, cavitation and reaction volume, and the sound emission of oxidative dye degradation by cavitation. For ensuring comparability and scalability, dimensionless similarity [...] Read more.

Fluid mechanical conditions are crucial for cavitation formation, and significantly influence chemical reactivity. This study investigates process conditions such as pressure, degassing, cavitation and reaction volume, and the sound emission of oxidative dye degradation by cavitation. For ensuring comparability and scalability, dimensionless similarity numbers aligned to the process were introduced. A further focus of the paper is reproducibility with corresponding guidelines. Measurements of dye degradation were carried out without additional chemicals. The oxidation process was assessed by the chemiluminescence of luminol. For this purpose, configurations with three nozzle sizes at different pressure differences were investigated. The generated cavitating jet was captured by imaging techniques and correlated to degradation. The most energy-efficient configuration was obtained by the smallest nozzle diameter of 0.6 mm at a pressure difference of 40 bar. Significant degassing occurred during cavitation. It was more pronounced with smaller nozzle diameters, correlating with higher degradation. Furthermore, discontinuous treatment methods can improve efficiency. Scaling to higher flow rates through multiple reactors in parallel proved more effective, compared to increasing the nozzle diameter or the pressure difference. For the same treated volume, two parallel reactors increased degradation by a factor of 1.35. The insights provide perspectives for optimizing jet cavitation reactors for water treatment. Full article

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

► Show Figures

Figure 1

22 pages, 5168 KiB

Open AccessArticle

Analysis of Carbon Dioxide Mineralization in Carbonates from Tampico-Misantla Basin, Mexico: Effect of Organic Matter Content

by Roxana López-Dinorín, Ana María Mendoza-Martínez, Diana Palma-Ramírez, Héctor Dorantes-Rosales, Ricardo García-Alamilla, Issis Claudette Romero-Ibarra and David Salvador García-Zaleta

Processes 2025, 13(4), 1087; https://doi.org/10.3390/pr13041087 - 4 Apr 2025

Abstract

The pursuit of effective climate change mitigation strategies is driving research into geological carbon dioxide (CO₂) storage. The present work explores the interaction of CO₂ with carbonate rocks from the El Abra formation in the Tampico-Misantla basin, focusing on the [...] Read more.

The pursuit of effective climate change mitigation strategies is driving research into geological carbon dioxide (CO₂) storage. The present work explores the interaction of CO₂ with carbonate rocks from the El Abra formation in the Tampico-Misantla basin, focusing on the comparative influence of organic matter (OM) content on mineralization processes, hypothesizing that variations in OM content significantly modulate the mineralization process affecting both the rate and type of carbonate formation. Expanding on a previous study, CO₂ is studied and injected under high-pressure (1350-2350 PSI) and high-temperature (60–110 °C) conditions into two contrasting samples: one with high OM content and another with low OM content. Structural, morphological, and physical adsorption changes were evaluated through Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) analyses. The findings indicate that the mineralogy of El Abra promotes secondary carbonate precipitation, with rock–fluid interactions significantly enhanced by brine presence. Samples with high OM exhibited a dramatic reduction in average particle size from 13 μm to 2 μm, along with the formation of metastable phases, such as vaterite—evidenced by XRD peak shifting and modifications in the FT-IR spectrum of carbonate bands. Meanwhile, low-OM samples showed an increase in particle size from 1.6 μm to between 3.26 and 4.12 μm, indicating predominant recrystallization. BET analysis confirmed a significant porosity enhancement in high-OM samples (up to 2.918 m²/g). Therefore, OM content plays a critical role in modulating both the rate and type of mineralization, potentially enhancing physical storage capacity in low-OM samples. These integrated findings demonstrate that OM critically governs calcite dissolution, secondary carbonate formation, and microstructural evolution, providing key insights for optimizing CO₂ storage in complex carbonate reservoirs. Full article

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

► Show Figures

Figure 1

29 pages, 1091 KiB

Open AccessReview

Molecularly Imprinted Polymers for Pollutant Capture and Degradation: A Snapshot Review

by Lázaro Adrián González-Fernández, Boris Mizaikoff, Nahum Andrés Medellín-Castillo, Javier Ernesto Vilasó-Cadre, Iván A. Reyes-Domínguez, Lorena Díaz de León-Martínez, Amelie Huber and Manuel Sánchez-Polo

Processes 2025, 13(4), 1086; https://doi.org/10.3390/pr13041086 - 4 Apr 2025

Abstract

Molecularly imprinted polymers (MIPs) are emerging as efficient materials for environmental remediation due to their dual functionality in selective pollutant adsorption and catalytic degradation. This review examines recent advances in MIP-based technologies, focusing on their role in photocatalysis and advanced oxidation processes. Experimental [...] Read more.

Molecularly imprinted polymers (MIPs) are emerging as efficient materials for environmental remediation due to their dual functionality in selective pollutant adsorption and catalytic degradation. This review examines recent advances in MIP-based technologies, focusing on their role in photocatalysis and advanced oxidation processes. Experimental findings highlight impressive degradation efficiencies, such as 95.8% methylene blue degradation using ZnO/CuFe₂O₄ MIPs and a 60% improvement in refractory organic degradation with TiO₂-MIPs. Adsorption studies show high uptake capacities, including 273.65 mg/g for ciprofloxacin with MOF-supported MIPs and 2350.52 µg/g for rhodamine B using magnetic MIPs. Despite these advancements, several challenges remain, including issues with long-term stability, scalability, and economic feasibility. Future research should prioritize optimizing polymer synthesis, integrating MIPs with high-surface-area matrices like MOFs and COFs and enhancing recyclability to ensure sustained performance. MIPs hold significant potential for large-scale water treatment and pollution control, provided their stability and efficiency are further improved. Full article

(This article belongs to the Special Issue Recent Advances in Wastewater Treatment Technology to Achieve Low Carbonization)

16 pages, 8321 KiB

Open AccessArticle

Impact of Burner Yaw and Tilt Angles on the NO Emissions and Slagging in a 330 MW Tangentially Fired Boiler Utilizing Zhundong Coal: A Numerical Study

by Yuhang Xiong, Ran Liu and Wenfeng Shen

Processes 2025, 13(4), 1085; https://doi.org/10.3390/pr13041085 - 4 Apr 2025

Abstract

Combustion of Zhundong coal in utility boilers is frequently challenged by ash-related issues (fouling/slagging) and stringent NO emission control requirements. This study conducted numerical simulations to investigate burner configuration effects, specifically yaw angle adjustments (modulating the imaginary tangential circle diameter, ITCD) and downward [...] Read more.

Combustion of Zhundong coal in utility boilers is frequently challenged by ash-related issues (fouling/slagging) and stringent NO emission control requirements. This study conducted numerical simulations to investigate burner configuration effects, specifically yaw angle adjustments (modulating the imaginary tangential circle diameter, ITCD) and downward tilt angles, on the NO emissions and slagging propensity in a 330 MW subcritical tangentially fired boiler. The results reveal a compromise mechanism between NO emission control and furnace slagging mitigation. ITCD reduction via yaw angle optimization increases furnace exit NO concentrations by 1.5–3% but decreases total deposition rates by 1.3–2%. By altering the burner downward tilt angle to 15° and 25°, NO emissions increase by 8% and 19%, respectively, with about a 7% reduction in total particle deposition rate. An optimal burner yaw and tilt angle is identified to achieve a compromise between NO emission and furnace slagging control. The findings provide some guidance for the combustion optimization of Zhundong coal-fired boilers. Full article

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

► Show Figures

Figure 1

21 pages, 6121 KiB

Open AccessArticle

Sulfidated Nano Zero-Valent Iron Sludge Biochar Composites for Efficient Tannic Acid Removal and Enhanced Anaerobic Digestion

by Qian Gao, Wenxia Zhai, Wencai Fu, Ling Liu, Yunpeng Zhu, Keyang Jiang, Sijia Zhu, Kaize Zhao, Zhaodong Qiu, Congcong Wang, Yuanyuan Zhao and Zhiwei Wang

Processes 2025, 13(4), 1084; https://doi.org/10.3390/pr13041084 - 4 Apr 2025

Abstract

Tannic acid (TA), a prevalent polyphenolic contaminant in industrial effluents, significantly inhibits microbial activity in anaerobic digestion, thereby diminishing wastewater treatment efficiency. In this study, a sulfidized nano zero-valent iron (S-nZVI) composite incorporated into sludge biochar (SB), abbreviated as SB-S-nZVI, was synthesized via [...] Read more.

Tannic acid (TA), a prevalent polyphenolic contaminant in industrial effluents, significantly inhibits microbial activity in anaerobic digestion, thereby diminishing wastewater treatment efficiency. In this study, a sulfidized nano zero-valent iron (S-nZVI) composite incorporated into sludge biochar (SB), abbreviated as SB-S-nZVI, was synthesized via a one-step hydrothermal method. The composite’s adsorption capacity for TA and its impact on anaerobic digestion were systematically evaluated. Experimental results showed that SB-S-nZVI achieved a TA removal efficiency of 99.31% under optimal conditions (S/Fe = 0.05, dosage = 0.3 g·L⁻¹), with a maximum adsorption capacity of 337.08 mg·g⁻¹. In anaerobic digestion, the addition of 0.03 g·L⁻¹ SB-S-nZVI enhanced chemical oxygen demand (COD) removal by 3.32%, increased specific methanogenic activity by 62.66%, and improved the microbial community composition, particularly enriching hydrolytic bacteria (Georgenia) and methanogenic archaea (Methanosaeta). The mechanistic analysis revealed that the FeS protective layer of SB-S-nZVI inhibited nano zero-valent iron oxidation and facilitated chemisorption-driven TA removal. This study presents an innovative approach for the integrated treatment of TA-contaminated wastewater by combining adsorption, degradation, and energy recovery. Full article

(This article belongs to the Special Issue Application of Biochar in Environmental Research)

► Show Figures

Figure 1

27 pages, 15371 KiB

Open AccessArticle

Mixing Times of Miscible Liquid Systems in Agitated Vessels

by Russell Miller, Isabella Cardona Barber, Leo Lue, Jan Sefcik and Neda Nazemifard

Processes 2025, 13(4), 1083; https://doi.org/10.3390/pr13041083 - 3 Apr 2025

Abstract

A better understanding of mixing times for mixed solvent systems in laboratory-scale vessels is crucial for improving mixing-sensitive processes such as antisolvent crystallisation. Whilst mixing in agitated vessels has been extensively studied using solutions of additives in the same solvent, there is very [...] Read more.

A better understanding of mixing times for mixed solvent systems in laboratory-scale vessels is crucial for improving mixing-sensitive processes such as antisolvent crystallisation. Whilst mixing in agitated vessels has been extensively studied using solutions of additives in the same solvent, there is very limited literature on the mixing of different miscible solvents and none which would be relevant to antisolvent crystallisation processes. In this work, the mixing times of water–ethanol systems in a 1 litre vessel, agitated by a pitched blade impeller with probes used as baffles, were investigated in the transitional flow regime using both experimental and computational fluid dynamics (CFD) approaches. We studied two scenarios: adding sodium chloride tracer to premixed water–ethanol solutions and adding ethanol containing a tracer to water. Mixing was investigated experimentally through conductivity measurements and computationally using large eddy simulations with the M-Star CFD software package. Empirical correlations from the Dynochem engineering toolbox were also used for comparison. The results showed significant run-to-run variability in the mixing times from both experiments and CFD simulations, with experimental ranges being notably wider than CFD ones under the given conditions. While the CFD simulations showed consistent mixing times across different solvent compositions, the experimental mixing times decreased with increasing ethanol content. The mixing times were approximately inversely proportional to the impeller speed. The CFD simulations indicated that 25–40 impeller rotations were required for homogenisation, while the experiments needed 25–100 rotations. The Dynochem correlations predicted 40 rotations, independent of speed, but could not capture the inherent variability of the mixing times. Full article

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

► Show Figures

Figure 1

16 pages, 1565 KiB

Open AccessArticle

Damage Evolution in High-Temperature-Treated Granite: Combined DIC and AE Experimental Study

by Xianggui Zhou, Qian Liu, Weilan Hu, Qingguo Ren and Shuwen Zhang

Processes 2025, 13(4), 1082; https://doi.org/10.3390/pr13041082 - 3 Apr 2025

Abstract

As mineral resource extraction progresses to greater depths, it has become imperative for geomechanical applications to understand the thermomechanical degradation mechanisms of rocks under thermal loading. To investigate the thermomechanical characteristics of granite subjected to thermal treatments ranging from ambient to 1000 °C, [...] Read more.

As mineral resource extraction progresses to greater depths, it has become imperative for geomechanical applications to understand the thermomechanical degradation mechanisms of rocks under thermal loading. To investigate the thermomechanical characteristics of granite subjected to thermal treatments ranging from ambient to 1000 °C, we conducted uniaxial compression tests integrating P-wave velocity measurements, digital image correlation (DIC), and acoustic emission (AE) monitoring. The key findings reveal the following: (1) the specimen volume exhibits thermal expansion while the mass loss and P-wave velocity reduction demonstrate a temperature dependence; (2) the uniaxial compressive strength (UCS) and elastic modulus display progressive thermal degradation, while the peak strain shows an inverse relationship with temperature; (3) acoustic emission signals exhibit a strong correlation with failure–time curves, progressing through three distinct phases: quiescent, progressive accumulation, and accelerated failure, and fracture mechanisms transition progressively from tensile-dominated brittle failure to shear-induced ductile failure with increasing thermal loading; and (4) the damage evolution parameter exhibits exponential growth beyond 600 °C, reaching 98.85% at 1000 °C, where specimens demonstrate a complete loss of load-bearing capacity. These findings provide critical insights for designing deep geological engineering systems involving thermomechanical rock interactions. Full article

(This article belongs to the Special Issue Structure Optimization and Transport Characteristics of Porous Media)

26 pages, 1612 KiB

Open AccessFeature PaperArticle

Techno-Economic Analysis of Hydrogen Transport via Truck Using Liquid Organic Hydrogen Carriers

by Carmine Cava, Gabriele Guglielmo Gagliardi, Enrica Piscolla and Domenico Borello

Processes 2025, 13(4), 1081; https://doi.org/10.3390/pr13041081 - 3 Apr 2025

Abstract

This study presents a techno-economic analysis of hydrogen transportation via liquid organic hydrogen carriers by road, comparing this option with compressed hydrogen (350 bar) and liquefied hydrogen. The analysis includes the simulation of hydrogenation and dehydrogenation reactors for the dibenzyltoluene/perhydro-dibenzyltoluene system using ASPEN [...] Read more.

This study presents a techno-economic analysis of hydrogen transportation via liquid organic hydrogen carriers by road, comparing this option with compressed hydrogen (350 bar) and liquefied hydrogen. The analysis includes the simulation of hydrogenation and dehydrogenation reactors for the dibenzyltoluene/perhydro-dibenzyltoluene system using ASPEN Plus, along with a cost assessment of compression, liquefaction, and trucking. A sensitivity analysis is also carried out, evaluating hydrogen transport at varying daily demand levels (1, 2, and 4 t/d) and transport distances (50, 150, and 300 km), with varying electricity prices and capital expenditures for hydrogenation and dehydrogenation units. Results indicate that compressed hydrogen is the most cost-effective solution for short distances up to 150 km, with a levelized cost of transported hydrogen ranging from 1.10 to 1.61 EUR/kg. However, LOHC technology becomes more competitive at longer distances, with LCOTH values between 1.49 and 1.90 EUR/kg at 300 km across all demand levels. Liquefied hydrogen remains the least competitive option, reaching costs up to 5.35 EUR/kg, although it requires fewer annual trips due to higher trailer capacity. Notably, at 150 km, LOHC transport becomes more cost-effective than compressed hydrogen when electricity prices exceed 0.22 EUR/kWh or when the capital costs for hydrogenation and dehydrogenation units are minimized. From an environmental perspective, switching from compressed to liquid hydrogen carriers significantly reduces CO₂ emissions—by 56% for LOHCs and 78% for liquid hydrogen—highlighting the potential of these technologies to support the decarbonization of hydrogen logistics. Full article

(This article belongs to the Special Issue Sustainable Hydrogen Production Processes)

16 pages, 2172 KiB

Open AccessArticle

Cooling Efficiency of Two-Phase Closed Thermosyphon Installed in Cast-in-Place Pile Foundation for Overhead Transmission Lines in High-Latitude Permafrost Regions

by Lei Zhao, Yao Xiao, Yunhu Shang, Yan Lu and Xuyang Wu

Processes 2025, 13(4), 1080; https://doi.org/10.3390/pr13041080 - 3 Apr 2025

Abstract

Ground temperature conditions are key factors affecting the stability of cast-in-place pile foundations for transmission towers in permafrost regions. With global climate warming, the ground temperature environment in permafrost regions has undergone significant changes, leading to an increasing risk of disasters for these [...] Read more.

Ground temperature conditions are key factors affecting the stability of cast-in-place pile foundations for transmission towers in permafrost regions. With global climate warming, the ground temperature environment in permafrost regions has undergone significant changes, leading to an increasing risk of disasters for these pile foundations. However, research on the prevention and control of pile foundation diseases caused by permafrost degradation is relatively limited, and engineering practices are insufficient. To address this, this study proposes embedding a two-phase closed thermosyphon (TPCT) inside a concrete pile foundation to create a composite structural system with both load-bearing and cooling functions. A mathematical model is developed to focus on the cooling performance and temperature control efficiency of the composite structure. The results indicate that: (1) The TPCT can alleviate, to some extent, the downward shift of the permafrost table around the transmission tower foundation due to climate warming. The cooling effect of the TPCT slows the rate of permafrost degradation, but its control effect on the permafrost table is limited. (2) The performance of the cast-in-place piles with an embedded TPCT is closely related to temperature, with an effective operational period from early October to late March each year. (3) This device effectively mitigates the impact of permafrost degradation due to climate change, significantly lowering the risk of foundation-related issues in transmission towers. The findings of this study are crucial for maintaining ground temperature stability in cast-in-place pile foundations for transmission projects in high-latitude permafrost areas, as well as enhancing the theoretical framework for pile foundation design. Full article

(This article belongs to the Topic Applied Heat Transfer)

20 pages, 3631 KiB

Open AccessArticle

A Mobile Energy Storage Configuration Method for Power Grids Considering Power Losses and Voltage Stability

by Xinhui Lai, Haojie Du, Fei Long, Yi An and Muliang Cai

Processes 2025, 13(4), 1079; https://doi.org/10.3390/pr13041079 - 3 Apr 2025

Abstract

The generation output of distributed power sources and the load possess periodic changes, which cause stability problems in the operation of the power grid. To ensure stability, energy storage devices are generally installed in the power grid, but their effectiveness is also limited [...] Read more.

The generation output of distributed power sources and the load possess periodic changes, which cause stability problems in the operation of the power grid. To ensure stability, energy storage devices are generally installed in the power grid, but their effectiveness is also limited by their fixed installation location and capacity. In this paper, to overcome the drawback of stationary energy storage devices, mobile energy storage devices are introduced to reduce power losses and enhance voltage stability. The installation location and capacity of these mobile energy storage devices can be changed with the generation output and load demands. Firstly, the influence of the mobile energy storage devices on power losses and voltage stability is analyzed. Next, a multi-objective optimization model is established to select the optimal installation location and the ideal capacity, which has optimization objectives including the improvement of voltage stability, the minimization of power losses, and the enhancement of utilization of energy storage devices. Finally, the particle swarm optimization algorithm is applied to solve the multi-objective optimization problem. The simulation results prove that the novel method of this paper enhances the dynamics of the power grid, i.e., the voltage vulnerability and power losses are reduced by 29% and 36%, respectively. In addition, it also increases the utilization rate of energy storage devices by 33.5% in different operating scenarios. Full article

(This article belongs to the Special Issue Advances in Renewable and Sustainable Engineering from the 5th International Conference on Sustainable Engineering Techniques)

► Show Figures

Figure 1

20 pages, 5836 KiB

Open AccessArticle

Biodegradable Polymer Composites Based on Polypropylene and Hybrid Fillers for Applications in the Automotive Industry

by Alina Ruxandra Caramitu, Magdalena Valentina Lungu, Romeo Cristian Ciobanu, Ioana Ion, Delia Pătroi, Beatrice Gabriela Sbârcea, Virgil Emanuel Marinescu and Doina Constantinescu

Processes 2025, 13(4), 1078; https://doi.org/10.3390/pr13041078 - 3 Apr 2025

Abstract

This study focuses on the development and characterization of biodegradable polymer composites consisting of a polypropylene (PP) matrix, carbon black pigment, and hybrid fillers. The fillers incorporated into these composites consisted of a blend of fibers and particles derived from natural, biodegradable materials, [...] Read more.

This study focuses on the development and characterization of biodegradable polymer composites consisting of a polypropylene (PP) matrix, carbon black pigment, and hybrid fillers. The fillers incorporated into these composites consisted of a blend of fibers and particles derived from natural, biodegradable materials, such as flax fibers (FFs) and wood flour (WF) particles. The compositions of polymer material were expressed as PP/FF/WF weight ratios of 100/0/0, 70/5/25, and 70/10/20. The polymer materials were prepared using conventional plastic processing methods like extrusion to produce composite mixtures, followed by melt injection to manufacture the samples needed for characterization. The structural characterization of the polymer materials was conducted using optical microscopy and X-ray diffraction (XRD) analyses, while thermal, mechanical, and dielectric properties were also evaluated. Additionally, their biodegradation behavior under mold exposure was assessed over six months. The results were analyzed comparatively, and the optimal composition was identified as the polymer composite containing the highest flax fiber content, namely PP + 10 wt.% flax fiber + 20 wt.% wood flour. Full article

(This article belongs to the Special Issue Development and Characterization of Advanced Polymer Nanocomposites)

► Show Figures

Figure 1

43 pages, 998 KiB

Open AccessReview

Malodorous Gases in Aquatic Environments: A Comprehensive Review from Microbial Origin to Detection and Removal Techniques

by Gabriela Meléndez-Plata, Jesus R. A. Mastrogiacomo, Martha L. Castellanos, Juan P. Romero, Victor Hincapié, Héctor Lizcano, Juan D. Acero, María Francisca Villegas-Torres, Jorge M. Gómez, Juan C. Cruz and Luis H. Reyes

Processes 2025, 13(4), 1077; https://doi.org/10.3390/pr13041077 - 3 Apr 2025

Abstract

Malodorous gases—particularly hydrogen sulfide (H₂S), ammonia (NH₃), and volatile sulfur compounds (VSCs)—significantly degrade water quality, threaten public health, and disrupt ecosystems. Their production stems from microbial activity, nutrient overload, and industrial discharges, often magnified by low dissolved oxygen. This [...] Read more.

Malodorous gases—particularly hydrogen sulfide (H₂S), ammonia (NH₃), and volatile sulfur compounds (VSCs)—significantly degrade water quality, threaten public health, and disrupt ecosystems. Their production stems from microbial activity, nutrient overload, and industrial discharges, often magnified by low dissolved oxygen. This review integrates current insights into the microbial sulfur and nitrogen cycles to elucidate how these gases form, and surveys advances in detection technologies such as gas chromatography and laser-based sensors. We also assess diverse mitigation methods—including biotechnological approaches (e.g., biofilters, biopercolators), physicochemical treatments, and chemical conversion (Claus Process)—within relevant regulatory contexts in Colombia and worldwide. A case study of the Bogotá River exemplifies how unmanaged effluents and eutrophication perpetuate odor issues, underscoring the need for integrated strategies that reduce pollution at its source, restore ecological balance, and employ targeted interventions. Overall, this review highlights innovative, policy-driven solutions and collaborative efforts as pivotal for safeguarding aquatic environments and surrounding communities from the impacts of odorous emissions. Full article

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

Journal Description

Processes

Latest Articles

Journal Menu

Journal Browser

Highly Accessed Articles

Latest Books

E-Mail Alert

News

Topics

Conferences

Special Issues

Topical Collections

Further Information

Guidelines

MDPI Initiatives

Follow MDPI