Search Results (68)

In order to solve the problems of mass transfer polarization spatiotemporal distribution variations, uncontrollable regulation error, and accelerated capacity decay caused by ion crossover in high-power vanadium liquid flow batteries (VFBs), a three-dimensional battery model with a flow-type flow field based on the three-dimensional transient COMSOL Multiphysics^® 6.1 numerical modeling method was developed in this study. The model combines the ion transmembrane migration equation with the mass transfer polarization theory, constructs an objective function to quantify the regulation error, and is validated by multifluid-field structural simulations. The results indicate the following: (1) Ion crossover induces a 3–5% electrolyte concentration deviation and a current density distribution bias reaching 11%; (2) The intensity of mass transfer polarization exhibits a linear increase with the flow rate difference between the positive and negative electrodes; (3) Ion crossover significantly degrades system performance, causing Coulombic efficiency (CE) and Energy efficiency (EE) to decrease by 1.1% and 1.5%, respectively. This research demonstrates that unlike conventional flow field optimization, our strategy quantifies the regulation error by directly compensating for the ΔQ caused by ion crossing, and further regulation minimizes the effect, providing a theoretical basis for mass transfer intensification and capacity recovery in flow batteries. Full article

Non-thermal technologies (NTTs) such as ultrasound (US), pulsed electric fields (PEF), high-pressure processing (HPP), cold plasma (CP), and pulsed light (PL) are emerging as versatile tools in food fermentation, offering microbial control and process enhancement without the detrimental heat effects of conventional methods. Operating at ambient low temperatures, these techniques preserve heat-sensitive compounds, modulate microbial activity, and improve mass transfer, enabling both quality retention and functional enrichment. Recent studies highlight their potential to stimulate metabolic pathways and enhance the release of bioactive compounds, opening new opportunities for fermented food production. The bibliometric analysis of the recent literature further reveals a growing interest in NTT applications in fermentation, with HPP and PEF showing the highest industrial maturity. Each technology exhibits distinct mechanisms and optimal niches across upstream, midstream, and downstream stages: HPP for uniform volumetric treatment, US for fermentation intensification, CP for surface-selective oxidative chemistry, PEF for membrane permeability control, and PL for rapid, residue-free decontamination. While the degree of industrial readiness varies, critical barriers such as scale-up limitations, high capital costs, energy distribution uniformity, process standardization, and techno-economic feasibility remain to be overcome. Beyond technical aspects, the successful commercialization of NTTs will also depend on addressing regulatory approval pathways, ensuring consumer trust and acceptance, and demonstrating their contribution to sustainability goals through lower energy use, reduced food waste, and environmentally responsible processing. Strategic, stand-alone, or hybrid applications of NTTs can therefore act not only as technological alternatives but also as enablers of a more sustainable, consumer-centered, and innovation-driven food system. Full article

Biogas is a renewable energy source produced by anaerobic digestion of organic waste. It can be upgraded to bio-methane by removing carbon dioxide, water and impurities. The present work focuses on carbon dioxide removal using both physical and chemical absorption in a micromixer. The absorption efficiency in the micromixer was studied under various conditions of co-current gas–liquid flow. With physical absorption, 25% of carbon dioxide could be removed from the biogas stream (with a liquid flowrate of 40 mL/min and a gas flowrate of 25 mL/min). In absorption with a chemical reaction, up to 88% of the carbon dioxide was eliminated with a catalyst concentration of 77.4 mol·m⁻³. In both cases, the space time was below 3 s. Liquid-side mass transfer coefficients as large as 3.5 s⁻¹ were achieved, which is at least two orders of magnitude higher than those reported in conventional absorbers. Full article

The propagation of high-frequency ultrasound waves will generate both physical and chemical effects as they propagate through a liquid medium, such as acoustic streaming, an acoustic fountain, and atomization. These phenomena are believed to be the main factors that contribute to the enhancement of mass transfer in the gas–liquid carbon dioxide (CO₂) absorption system. Computational Fluid Dynamic (CFD) simulation is one of the powerful tools that can be used to model the complex hydrodynamic behavior induced by the propagation of ultrasound waves in the liquid medium. In this study, the ultrasonic irradiation forces were simulated via the momentum source term method using commercial CFD software (ANSYS Fluent V19.1). In addition, a parametric study was conducted to investigate the influences of absorber height and ultrasonic power on the hydrodynamic mixing performance. The simulation results indicated that enhanced mixing and a higher intensification factor were achieved with increased fountain flow velocity, particularly at the lowest absorber height and highest ultrasonic power. Conversely, the energy efficiency was improved with the increase of absorber height and decrease of ultrasonic power. To determine the optimal combination of absorber height and ultrasonic power, this trade-off between the energy efficiency and intensification in the ultrasonic-assisted absorption system (UAAS) is a crucial consideration during process scale-up. Full article

To enhance the low-efficiency but potentially health and environmentally friendly aqueous decaffeination process, ultrasound-assisted aqueous extraction (UAAE) has recently been proposed. A novel concept of intermittent extraction water change to further enhance UAAE has also been mentioned, but not yet studied in detail. For this reason, a mathematical model that can be used to predict the concentration evolutions of caffeine during UAAE and conventional aqueous extraction (CAE) of whole green robusta coffee beans is herein proposed. The model consists of terms representing transient intra-bean caffeine and water diffusion as well as molar fluxes of caffeine and water on the bean surface. After validation, the model was used to investigate the effects of extraction temperature, bean-to-water mass ratio and frequency of extraction water change on caffeine concentration evolutions. Simulation results show that UAAE exhibits around 10% higher caffeine removal rates than CAE at all investigated conditions. Extraction temperature of 70 °C, bean-to-water ratio of 1:3, and extraction water change at every 1 h interval are noted as the most appropriate conditions for UAAE. The required extraction durations of UAAE under these conditions are 13 h and 24 h to meet the US and European Union standards, respectively. Full article

Low-temperature Fischer–Tropsch (LTFT) synthesis converts syngas to diesel/wax at 200–250 °C. The LTFT reaction has recently received renewed interest, as it can be used for converting syngas from renewable sources (biomass and waste) to high-value fuels and chemicals. Conventional LTFT reactors, such as fixed-bed and slurry reactors, are not entirely suitable for bio-syngas conversion due to their smaller scale compared to fossil fuel-based syngas processes. This review explores advancements in intensifying LTFT reactors suitable for bio-syngas conversion, enabling smaller scale and dynamic operation. Various strategies for enhancing heat and mass transfer are discussed, including the use of microchannel reactors, structured reactors, and other designs where either one or both the heat and mass transfer are intensified. These technologies offer improved performance and economics for small LTFT units by allowing flexible operation, with increased syngas conversion and reduced risk of overheating. Additionally, this review presents our outlook and perspectives on strategies for future intensification. Full article

In many technological processes, liquids or mixtures of mutually insoluble liquids, suspensions, emulsions, etc., are used as working media. The transformation of the energy supplied to such media and the related effects can be usefully realised not only for the implementation of technological processes but also for their intensification. In this context, an important task in increasing the efficiency of the use of the supplied energy is the analysis of the processes that take place in liquids or their mixtures at the level of thermodynamic saturation. In this work, it is shown that the creation of thermodynamic conditions for local energy transformation in a disperse system significantly increases the intensity of heat and mass transfer processes, and in some technologies, e.g., homogenisation, dispersion can be increased by 2–3 times in comparison with traditional methods at the same energy consumption. Full article

Fluidized bed-chemical vapor deposition (FB-CVD) technology stands as a cross-cutting achievement of fluidized bed technology in chemical engineering and chemical vapor deposition (CVD) in materials science, finding applications in particle coating, granulation, and material preparation. As compared to conventional CVD technology, FB-CVD distinguishes itself through enhanced heat/mass transfer efficiency, achieving a uniform coating layer while maintaining low production costs. Given the related research on FB-CVD micro-nano particle coating, the mechanism of particle fluidization and chemical vapor deposition, and the difficulty of micro-nano particle agglomeration were summarized. The process intensification of micro-nano particle fluidization assisted by particle design and external force field, such as vibration field, magnetic field, and sound field, and micro-nano particle chemical vapor deposition coating were summarized. In particular, applications of FB-CVD micro-nano particle coating are introduced. Finally, the opportunities and challenges faced by FB-CVD micro-nano particle coating technology are discussed, and the development prospect of this technology is prospected. This review is beneficial for the researchers of the fluidization field, and also the particle coating technology. Full article

With the growing demand for drug products requiring lyophilization, it is essential to either expand aseptic drying capacity or improve the efficiency of existing capacity through process intensification, ensuring that resources are utilized to their full potential. In this regard, mathematical models are highly recommended to assist professionals in process optimization. To effectively utilise these models, it is also essential to develop robust techniques for determining key parameters, including the product resistance to vapour flow. Traditional experimental methods for evaluating this coefficient are time-intensive and/or require the insertion of probes into the product, which is not feasible at a manufacturing scale. This study addresses these challenges by introducing a novel deep learning framework designed to predict the mass transfer coefficient directly from Field Emission Scanning Electron Microscope images. This approach significantly streamlines the evaluation process, leveraging the high-resolution capabilities of Field Emission Scanning Electron Microscope for detailed analysis. In this work, we focus on advanced Field Emission Scanning Electron Microscope image processing, choice of strategic convolutional neural network configuration, and thorough model performance evaluation to predict the mass transfer coefficient. Given the frequent scarcity of datasets in this field, we have employed data augmentation techniques to enhance the robustness of our model. The results demonstrate good predictive accuracy (error on the interpolation test data lower than 5%), highlighting the potential of this framework to facilitate the assessment of mass transfer coefficients in freeze-dried products. Full article

Liquid–liquid mass transfer is crucial in chemical processes like extraction and desulfurization. Traditional tube-in-tube millireactors often overlook internal flow dynamics, focusing instead on entry modifications. This study explores mass transfer enhancement through structured inserts (twisted tapes, multi-blades) and inlet designs (multi-hole injectors, T-mixers). Using high-speed imaging and water–succinic acid–butanol experiments, flow patterns and mass transfer rates were analyzed. Results show annular and dispersion flows dominate under tested conditions with structured inserts lowering the threshold for dispersion flow. Multi-hole injectors improved mass transfer by over 40% compared to T-mixers in plain tubes, while C-tape inserts achieved the highest volumetric mass transfer coefficient (2.43 s⁻¹) due to increased interfacial area and droplet breakup from energy dissipation. This approach offers scalable solutions to enhance tube-in-tube millireactor performance for industrial applications. Full article

Many designs of industrial reactors stem from designs from the 1960s–1970s. For a wide range of reactions, these designs lead to suboptimal reaction configurations due to limitations in heat- or mass-transfer. Process intensification has come up with a different approach, resulting in micro- and mini-reactors being safer and more cost-effective on a full industrial scale. However, based on the experience in the suboptimal reactor designs, the reaction rates of these reactions seem too low for full-scale reactions in a mini reactor. We suggest a test for the reaction rate based on a generalized model in combination with a specific type of mini-reactor: the rotor–stator spinning disc reactor. The generalized model is based on existing models on residence time distribution in such reactors. It does not need to be tailor-fitted for a specific rotor–stator spinning disc reactor that is used for the test, as is the case with current models. In this article, we show that our simplifications induce a difference in outcome in reaction rate of less than 10% with the existing models. Experiments with the well-studied chemical reaction of the hydrolysis of acetic anhydride show that the reaction rates calculated based on this scan fall within the range of reported data from the literature. Full article

The monumental scale agricultural infrastructure systems built by Andean peoples during pre-Hispanic times have enabled intensive agriculture in the high-relief, arid/semi-arid landscape of the Southern Peruvian Andes. Large tracts of these labor-intensive systems have been abandoned, however, owing in large measure to a range of demographic, economic, and political crises precipitated by the Spanish invasion of the 16th century CE. This research seeks to better understand the dynamics of agricultural intensification and deintensification in the Andes by inventorying through the semantic segmentation of active and abandoned agricultural fields in satellite imagery across approximately 77,000 km² of the Southern Peruvian Highlands. While manual digitization of agricultural fields in satellite imagery is time-consuming and labor-intensive, deep learning-based semantic segmentation makes it possible to map and classify en masse Andean agricultural infrastructure. Using high resolution satellite imagery, training and validation data were manually produced in distributed sample areas and were used to transfer-train a convolutional neural network for semantic segmentation. The resulting dataset was compared to manual surveys of the region and results suggest that deep learning can generate larger and more accurate datasets than those generated by hand. Full article

Structured Fischer–Tropsch synthesis catalysts were tested in tubular reactors of industry-standard diameters of 0.5 or 0.75 inches. The structured catalyst bed was manufactured by the obturation of a straight bunch of graphite-based extrudates (D = 1.5 mm, L = 30 mm). A conventional loose bed of granulated catalyst (D = 1.5 mm, L = 3 mm) was tested as a reference. In a 1000–3000 h⁻¹ syngas space velocity range, structured and loose catalyst bed testing showed no significant differences in their main catalytic parameters. Nevertheless, their C₅₊ hydrocarbon group composition was quite different, i.e., the alkene fraction rose from 9 to 23%, while n-alkanes dropped from 81 to 64%. This could be a result of secondary reaction intensification in the conventional loose bed due to its zeolite acid site’s higher availability. Further FTS testing of the structured catalysts in 4000–6000 h⁻¹ manifested distinctive limits in C₅₊ productivity for 0.5 and 0.75 inches of 512 kg C₅₊/(m³ reactor·h) and 362 kg C₅₊/(m³ reactor·h), respectively. This may be explained by limitations in structured bed thermal conductivity. It suggests that the arrangement of extrudates in the structured catalyst can significantly affect the reaction heat and mass transfer conditions and affords new opportunities for group composition control by means of catalyst bed organization. Full article

In mariculture facilities, bacterial infections pose significant production challenges, with potentially catastrophic impacts on fish species. Bacterial co-infections are a widespread phenomenon in the natural marine environment, although their impact on aquatic organisms remains poorly investigated. This study aimed to detail the pathological findings associated with a natural bacterial co-infection caused by three different pathogens, namely Photobacterium damselae subsp. piscicida, Tenacibaculum maritimum and Vibrio sp., as the cause of mass mortality in European sea bass. The fish had been reared in open-net cages in Sicily and later transferred for experimental research purposes to a user establishment after immunization with an inactivated vaccine. Macroscopic, cytological and histopathological examinations were performed on 109 animals, and bacterial species were identified by the 16S rRNA gene. Overall, ulcerative skin lesions, necrotizing myositis and tail rot with occasional tail loss were associated with tenacibaculosis and vibriosis, while P. damselae subsp. piscicida mainly caused granulomatous inflammation in the spleen and head kidney. Finally, an injection site reaction due to the oil-adjuvanted vaccine administered intraperitoneally was observed in the abdominal fat. Understanding the impact of bacterial pathogens is essential to manage the health and welfare of farmed fish, and the importance of a good health monitoring program cannot be overstated to avoid outbreaks and the possible emergence of new pathogens due to the intensification of the production systems, antibiotic resistance and climate changes. The study would also highlight the importance of the quarantine period when animals supplied for research come from aquaculture farms and how the main goal in the near future should be to better define the procedures to provide completely pathogen-free animals. Full article

Carbon dioxide (CO₂) is a greenhouse gas, and its resource use is vital for carbon reduction and neutrality. Herein, the nucleophilic addition reaction of calcium carbide (CaC₂) to CO₂ was studied for the first time to synthesize propiolic and butynedioic acids by using CuI or AgNO₃ as catalyst, Na₂CO₃ as additive, and triphenylphosphine as ligand in the presence/absence of a hydrogen donor. The effects of the experimental conditions and intensification approach on the reaction were investigated. The reactivity of CaC₂ is closely associated with its synergistic activation by the catalysts, solvent, and external intensification, such as the ultrasound and mechanical force. Ultrasound helps to promote the reaction by enhancing the interfacial mass transfer of CaC₂ particulates. Mechanochemistry can effectively promote the reaction, yielding 29.8% of butynedioic acid and 74.8% of propiolic acid after 2 h ball milling at 150 rpm, arising from the effective micronization and interfacial renewal of calcium carbide. The present study sheds a light on the high-value uses of CO₂ and CaC₂ and is of reference significance for the nucleophilic reaction of CaC₂ with other carbonyl compounds. Full article