Enhanced electric field intensity in transverse microchannel charcoal electrode for facilitating electrochemical demulsification rate of oil-in-water droplets.

• A novel computational approach is presented for CO 2 absorption in NaOH-Na 2 CO 3. • The developed approach combines thermodynamic and CFD modelling. • A good agreement between predictions and experimental measurements is obtained. • The models reveal key mechanisms and phenomena that dictate process dynamics. • The interplay between transport and chemical reactions is studied in detail. Carbonation processes find numerous applications; however, the complex nature of their underlying mechanisms has hindered their detailed understanding. The fluid dynamics occurring within stirred tanks, the multiphase CO 2 bubble flow, as well as the interphase mass transfer and chemical reactions, are all simultaneously affecting the carbonation process. Furthermore, the interplay between all those mechanisms and phenomena deems the in-depth mechanistic understanding of the process dynamics via experimental studies a rather challenging task. In this work, a novel combined computational approach, consisting of a thermodynamic and a three-dimensional CFD model, is developed for the CO 2 absorption in NaOH-Na 2 CO 3 liquid solutions. Information on the equilibrium conditions is provided by the thermodynamic to the CFD model, which calculates the dynamics of CO 2 absorption in the solution. These results are fed back to the thermodynamic model, enabling the simulation of the chemical reactions, in conditions closer to the actual experiments. The results are validated using experimental measurements for the CO 2 flow and the pH within the solution, achieving good agreement. This approach enables the integration of insights from both methodologies, revealing the relationship between the different phenomena and mechanisms that constitute the carbonation process, which might be challenging to define solely experimental results. Specifically, it elucidates the process dynamics which unravels key mechanisms during the carbonation process. The combined computational approach can assist the knowledge-based process and reactor design, while it can also pave the way for the optimized scale-up of carbonation-precipitation processes.

The In Vessel Melt Retention (IVMR) strategy developed for Light Water Reactors (LWR) is an appealing solution for the mitigation of many Severe Accident (SA) scenarios. This approach is typical of innovative reactors like the AP1000 and the Hualong One, both GW-size Pressurized Water Reactors (PWR). In this paper, the IVMR application for integral PWRs (iPWR) is investigated. Indeed, many iPWRs rely on IVMR as a mitigation strategy. These kinds of reactors are characterized by an electrical power output generally lower than 300 MWe, an integral layout and the use of passive safety systems. During a postulated accidental sequence that leads to fuel melting, the molten corium relocates down to the lower plenum of the Reactor Pressure Vessel (RPV). By flooding the reactor cavity where the RPV is immersed, the external face of the vessel is cooled, and corium is maintained inside the lower head. The overall phenomenology occurring during IVMR in an iPWR is similar to the one in a high-power LWR, but some discrepancies are expected due to the different design features. This paper describes a 0D model developed to perform the steady-state analysis of idealized cases in an iPWR. The aim is to provide an initial exploration of the safety margins for several existing iPWR designs, considering available data and plausible assumptions for the unknown parameters, while recognizing the inherent uncertainties in the analysis. The 0D model has been written in Python language and conceived to be design independent. By adjusting a few geometrical or material characteristics, it may be readily adapted to the generic iPWR layout. The development activity has been carried out in the framework of the SASPAM-SA Horizon Euratom project. The main goal achieved is the identification of some specific features characterizing the phenomenon occurring in an iPWR. Among the variations, it is interesting to note that the molten pool is relatively shallow in height because of the vessel's large diameter (integral RPV) compared to the lower mass of relocated materials. This has an impact on the heat flux profile along the vessel wall. Another difference is the rather thick oxide crust associated with the low residual power in the pool, for which the modelling approach has been adapted with respect to what is usually done for the analysis of high-power reactors. The outcomes obtained with this work will also prepare the next steps of SASPAM-SA project, identifying the models in SA codes needing some improvements. Integral reactor calculations focused on the IVMR are also planned: they will be compared to the results of the current 0D approach. • A simple Python tool was developed for In Vessel Retention in iPWR. • The activity has been developed in SASPAM-SA Horizon Euratom project. • Five reactor designs have been selected and their results analyzed. • Specificities of iPWR have been identified and IVR appears feasible.

Particle atomic layer deposition in fluidized bed reactors: An updated perspective on reactor design and low-pressure fluidization

Electrochemical (EC) technologies are emerging as key enablers for the sustainable recovery of critical raw materials (CRMs) from technological waste, aligning with the objectives of the European Union’s circular economy and the Net-Zero Industry Act. This review examines recent advances in EC methods, including electrowinning, electrorefining, EC leaching, electrodialysis, capacitive deionization, and mediated EC reactions, highlighting their mechanisms and scalability. While laboratory-scale technological innovations demonstrate promising selectivity and energy efficiency, industrial deployment remains constrained by input waste variability. Comparative analysis reveals that EC technologies offer distinct advantages over conventional metallurgical approaches, particularly in terms of environmental impact and modular design. However, gaps persist in techno-economic validation, lifecycle assessment, and standardization of reactor designs. This review identifies key research priorities and outlines pathways for scaling up EC-based recovery systems to meet future CRMs demand. • Electrochemical processes enable recovery of critical metals from waste. • Renewable energy can improve sustainability and reduce emissions. • Pilot studies confirm feasibility but highlight scale-up challenges. • Key gaps remain in reactor design, TEA, and life-cycle assessment.

Conceptual design of fast Molten salt reactors with novel secondary shutdown systems

Parameter analysis of the cold-leg LBLOCA initiating event of the SCW-SMR reactor concept

Understanding fluid flow through porous media with complex geometries is essential for improving the design and operation of packed-bed reactors. Most existing studies focus on spherical packings, having as a consequence that accurate models for irregular interstitial geometries are scarce. In this study, we numerically investigated the flow through a set of packed-bed geometries consisting of square bars stacked on top of each other and arranged in disk-shaped modules. Rotation of each module allows the generation of a variety of geometrical configurations at Reynolds numbers of up to 200 (based on the bar size). Simulations were carried out using the open-source solver OpenFOAM. Selected cases (e.g., α = 30°, Re p = 100, 200) were compared against Particle Image Velocimetry measurements. Results reveal that, based on the relative rotation angle, the realized geometries can be classified as channel-like ( α ≤ 10°) and lattice-like ( α ≥ 15°), fundamentally altering the friction factor. Furthermore, the maximum friction factor obtained in the creeping regime occurred at α = 25°, whereas in the inertial regime, this occurred at α = 60°. The module-equivalent diameter, based on the angle-dependent wetted surface area, collapses the friction factor onto the Ergun correlation and yields good permeability predictions for the lattice-like geometries. • Pressure drop systematically quantified across 19 rotation angles. • Wetted surface area governs drag in non-spherical beds. • Two analytical models predict permeability of complex geometries. • Diameter ratio and tortuosity reliably classify packed-bed flow regimes.

Control system design of a multipurpose small modular reactor with once-through steam generator under cogeneration condition

Generative design of high-power thermochemical energy storage reactors via multiphysics-driven topology optimization

This work numerically investigates the pyrolysis of five common thermoplastics using a homogeneous, single-particle model (0D) to elucidate the interplay between convective heat transfer and reaction kinetics. The results reveal a fundamental competition between external heat supply and the endothermic cooling effect of the reaction, manifesting as a temperature plateau where heat input is balanced by the reaction enthalpy. We demonstrate that enhanced heat transfer—achieved via smaller particle sizes or higher Nusselt numbers—shifts the process toward higher reaction rates and temperatures. To quantify this behavior, we utilize the Pyrolysis number ( Py ), defined as the ratio of the characteristic chemical reaction time to the convective heat transfer time. A universal inverse correlation is identified between the dimensionless pyrolysis time and Py , valid across all investigated polymers and operating conditions. This correlation delineates two distinct operational regimes: reaction-limited control ( Py > 1) and convective-heating limited control ( Py < 1). These findings provide a predictive framework for optimizing heating rates and estimating residence times for complete conversion. Finally, comparison with particle-resolved (1D) simulations shows that neglecting intra-particle heat conduction causes faster heating and pyrolysis conversion, thereby underestimating the overall pyrolysis duration. • Revealed the interplay between convective heating and reaction kinetics in plastic pyrolysis. • Used the Pyrolysis number to delineate regimes governed by heating rate versus reaction rate. • Built a predictive model for pyrolysis time to guide reactor design optimization. • Pinpointed optimal heating conditions at a Pyrolysis number near unity. • Quantified the influence of intra-particle conduction versus convection on the overall pyrolysis conversion.

Recent advances in innovative electrode and reactor designs for microbial electrochemical CO₂ conversion

Simulation of water activation in the KATANA activation loop of the TRIGA reactor

• Elucidating the anaerobic digestion mechanisms for food-waste valorization • Evaluation of pre-treatments enhancing biodegradability and methane yield • Identification of key factors influencing digestion efficiency and stability • Discussion of challenges and future pathways for AD advancement The escalating global volume of food waste poses significant environmental challenges but also represents a substantial opportunity for sustainable energy generation. Anaerobic digestion (AD) is a leading technology that converts this waste into biogas, offering a dual solution for renewable energy production and waste management. This comprehensive review delves into the application of AD for food waste, providing an in-depth analysis of the underlying biochemical processes and critical operational parameters that govern biogas yield such as; temperature, pH, and organic loading rate. It further explores a range of physical, chemical, and biological pre-treatment methods to enhance the efficiency of waste breakdown. The review further investigates recent advancements, including innovative reactor designs, co-digestion strategies, and process optimization techniques, all aimed at improving system performance and scalability. While addressing key challenges like feedstock variability, process instability, and inhibition, the review proposes practical mitigation strategies. Finally, it evaluates the environmental and economic viability of AD, discussing its integral role in circular economy frameworks by transforming waste into valuable resources. This synthesis aims to guide future research and accelerate the adoption of anaerobic digestion as a cornerstone technology for sustainable waste-to-energy conversion.

• Assessment of date seeds pyrolysis behaviour was complemented. • Model-free kinetics was employed to analyze the process kinetics. • Combined kinetics displays the Ea of 272.4 ± 11.8 kJ mol -1 having R 2 of 0.9948 • ANN, BRT, C&RT and MARS accurately predict the Ea for date seeds pyrolysis The pyrolysis potential of date seeds (DS) (an abundant agricultural residue that can support sustainable and resilient energy systems) as a renewable bioenergy feedstock was examined. Thermogravimetric analysis (TGA) of date seeds was performed from ambient temperature to 1000 °C under nitrogen at heating rates of 6, 9, 12, and 15 °C/min. The feedstock showed high volatile matter and a higher heating value (HHV) of 20.185 MJ/kg, confirming its suitability for thermochemical conversion. Isoconversional model-free methods such as Friedman (FR), Kissinger Akahira-Sunose (KAS), Ozawa-Flynn-Wall (OFW) and an advanced Vyazovkin (VZ) approach were applied over a conversion range of 0.2 to 0.8. A linear combined kinetics analysis gave an apparent activation energy (E a ) of 272.4 ± 11.8 kJ/mol with a correlation coefficient of 0.9948 with the reaction order of 7.75 ± 0.27. Four machine learning (ML) models, including Artificial Neural Networks (ANN), Classification and Regression Trees (C&RT), Boosted Regression Trees (BRT), and Multivariate Adaptive Regression Splines (MARS), were used to predict E a obtained from thermogravimetric data. The ANN achieved the best performance metrics, with a coefficient of determination (R2) of 0.985 and a Root Mean Squared Error (RMSE) of 3.84. The integrated kinetic and machine-learning framework provides reliable estimates of E a for DS pyrolysis. The predicted E a determines the temperature sensitivity of pyrolysis, setting the required heating rate, residence time, and temperature profile in the reactor. These results provide process-level input for reactor design, scaling-up, and optimizing bioenergy production from DS waste.

• Microwave assisted regeneration of CO 2 adsorbents was comprehensively reviewed. • Influence of dielectric loss and hotspots on regeneration performance was analyzed. • Design strategies for microwave-responsive adsorbents with high efficiency were summarized. • Engineering and scale-up principles for microwave regeneration reactors were proposed. Conventional temperature-swing adsorption (TSA) for CO 2 capture is energy intensive, typically requiring above 3.5 MJ/kg CO 2 . Microwave-assisted regeneration technology has emerged as a promising alternative strategy due to the unique volumetric heating and selective heating advantages of microwave heating. This review provides a comprehensive analysis of the mechanisms and applications of microwave-enhanced adsorbent regeneration of CO 2 adsorbents. First, the fundamental principles of microwave-induced TSA process intensification are elucidated by establishing correlations between the dielectric loss factor ε″ of CO 2 adsorbents and their key performance, including regeneration energy demand and desorption rate, highlighting the role of microwave-induced hotspots. Consequently, the review summarizes the design principles and synthesis strategies from diverse fields for engineering microwave-responsive adsorbents with targeted microwave-absorbing capability. Next, this review expands the scope to reactor-scale considerations and process integration, where the impact of system design, including impedance matching, cavity geometry, power feeding strategies, and gas-solid hydrodynamics, on overall energy utilization and temperature uniformity is examined. A comparative analysis of fixed-bed, fluidized-bed, and moving-bed configurations within microwave fields is presented, highlighting their respective synergies and operational constraints for scalable regeneration. Moreover, significant scientific and engineering challenges of microwave-assisted regeneration technology are reviewed, including insufficient fundamental understanding of quantitative relationships between hotspot intensity, desorption kinetics and long-term adsorbent deactivation, as well as scale-up problems associated with heating uniformity and limited microwave penetration depth. It remains an essential need to develop unified engineering guidelines by bridging advanced multiphysics modelling with practical reactor design, with the aim to achieve large scale and low energy CO 2 capture by establishing a competitive technological pathway.

Gas hydrate-based carbon capture, transport, and sequestration (GH-CCS) has emerged as a promising alternative for mitigating anthropogenic CO2 emissions. Gas hydrates selectively encapsulate CO2 within crystalline water frameworks under moderate pressure and temperature conditions, offering advantages such as solvent-free operation, high selectivity, and inherent stability for long-term storage. This review provides a comprehensive evaluation of GH-CCS across the entire process chain, including CO2 capture, transport, and sequestration. Recent advances in hydrate-based separation from fuel gas (CO2/H2) and flue gas (CO2/N2) streams are discussed, with emphasis on phase behavior, promoters, and reactor design. Developments in hydrate-based CO2 transport are examined, focusing on slurry transport, rheology, and flow assurance challenges. Sequestration strategies in marine sediments, geological formations, and permafrost regions are also reviewed, including CO2-CH4 exchange mechanisms. Key technical and economic challenges such as hydrate formation kinetics, energy requirements, scale-up feasibility, and long-term storage stability are critically assessed, and future research directions are outlined.

Enhancing photocatalytic degradation: A comprehensive study on radiation field and photon distribution in concentric annular reactor.

This work addresses a key challenge in scaling up mechanochemical synthesis: deriving a kinetic model when unpredictable formation and intricate interaction of multiple crystalline phases occur during solid-state transformations. Reaction kinetics translate our understanding of chemical processes into mathematical rate expressions used for reactor design and evaluation, thus representing a challenge to be addressed for the scale up at the industrial level. Choosing co-crystallization of chloro-3-sulfamoylbenzoic acid (CSBA) and isonicotinamide (INA) as a model system, at first we employ time-resolved in situ powder X-ray diffraction (PXRD) and multivariate curve resolution-Alternating Least Squares (MCR-ALS) analysis to quantify and resolve the evolution of crystalline intermediates under varying methanol-assisted conditions. Our data show that even small changes in the amount of methanol can dramatically alter the kinetic profile, stabilise transient phases (including some that were previously unreported) and alter the overall reaction pathway. We then demonstrate the robust deconvolution of overlapping phases and the extraction of quantitative rate parameters that rationalize the observed behaviour by integrating kinetic modelling as a soft-hard constraint in the MCR-ALS workflow. The validation of the established MCR-ALS workflow is achieved by applying a phenomenological kinetic modelling tailored to rationalize the mechanochemical reaction rates. These results establish a broadly applicable platform for analysing and controlling the complex phase evolution, along with the derivation of a kinetic model instrumental to mechanochemical process development and scaling up, thereby supporting the transition of sustainable solid-state syntheses from the laboratory to industry.

Hydrogen peroxide (H2O2), as a green and versatile oxidant, holds significant promise across environmental and energy-related applications. However, its industrial production via the conventional anthraquinone process is plagued by issues including raw material hazards, high energy consumption, complex separation processes, and safety concerns in storage and transportation. In response, photo-electrochemical production has emerged as a sustainable alternative for on-site H2O2 synthesis via two-electron pathways, namely the oxygen reduction reaction (ORR) and water oxidation reaction (WOR). This review systematically summarizes recent progress in photo-electrochemical H2O2 production, focusing on fundamental mechanisms, catalyst design strategies, and system-level innovations. The working principles of photo-electrochemical systems are amply introduced, emphasizing charge separation and surface reaction dynamics. Subsequently, the thermodynamic and kinetic characteristics of ORR and WOR pathways are analyzed, with an emphasis on selectivity regulation between two-electron and four-electron routes. Advances in photo-electrochemical materials are comprehensively reviewed. Key performance indicators such as faradaic efficiency (FE), H2O2 yield, and stability are critically evaluated. Furthermore, emerging applications integrating H2O2 production with environmental remediation (e.g., pollutant degradation, disinfection) and energy conversion systems (e.g., H2O2 fuel cells) are discussed, along with reactor design and scale-up strategies. Finally, current challenges and future directions are outlined, including stability enhancement, selectivity control, and the integration of renewable energy sources. This review aims to provide a comprehensive reference for advancing green and decentralized H2O2 production through photo-electrochemical technologies.