Simple Reactor Research Articles

Microwave-Assisted Oxidation of N2 into NOx over a La-Ce-Mn-O Perovskite Yielding Plasmas in a Quartz Flow Reactor at Atmospheric Pressure

N2 oxidation to NOx is a challenging reaction, and alternative routes to the industrial Ostwald process are of interest. A perovskite under flowing O2-N2 mixtures at atmospheric pressure in a quartz tube reactor was irradiated by microwaves (MW), leading to the formation of hot spots and plasmas within the catalyst bed. NOx concentrations up to 2.5 vol.% in one pass were obtained at 600 W. Using a lower MW power of 100 W led to a pulsed mode yielding lower NOx concentrations and no noticeable damage to the quartz reactor. The formation of plasma was strongly dependent on the perovskite bed packing. The perovskite acted primarily as a susceptor and likely also as a catalyst, although the proportion of heterogeneous and homogenous reactions could not be determined in the present study. The simple reactor layout allowing operation at atmospheric pressure is promising for the development of practical MW-assisted N2 fixation technologies.

Investigation of [formula omitted] formation in non-premixed, swirl-stabilised, wet hydrogen/air gas turbine combustor

In line with the Paris Agreement and the United Nations Sustainable Development Goals, the use of fossil fuels is to be phased out in the coming decades. Fossil-free hydrogen is a promising candidate for decarbonising the energy sector. However, hydrogen combustion is known to produce undesirable emissions such as nitrogen oxides (NOx) and calls for mitigation measures such as steam-diluted hydrogen combustion, which is known to reduce the NOx emissions. This study focuses on improving the understanding of NOx formation in a swirl-stabilised, steam-diluted, non-premixed hydrogen/air combustion using high-fidelity large eddy simulation (LES) and zero-dimensional (0D) perfectly stirred reactors (PSR). The LES results are used to identify four salient points in the domain where the NOx chemistry is analysed in detail. These points are chosen in the main flame, flame tail, post-flame and central recirculation regions. Note, the high heat release rate (HRR) region is referred to as the main flame while the flame tail denotes the low-HRR and V-shaped flame region adjacent to the main flame. Based on the LES data at these chosen points, the contribution of the major NO production pathways such as the Zeldovich mechanism, extended Zeldovich mechanism, N2O route and the NNH route are studied and reveal different rates of production of NO (i.e. ROPNO). Also, the role of individual reactions in NO production and consumption is investigated. Furthermore, reaction pathway diagrams illustrating the chemical pathways leading to NO are visualised. The sensitivity of NO to each reaction is also reported. These analyses provide insights into the NO chemical pathways observed at the salient points across the domain. The dominance of the Zeldovich mechanism remains but is much less compared to that in dry hydrogen combustion as its contribution to ROPNO is less than 20% at all the points considered. However, the extended Zeldovich mechanism is significant at all the points. The NNH route is observed to be important in the flame regions. The major NNH reaction contributing to ROPNO in the flame regions is NNH+O⇌NH+NO. Furthermore, the complex NO chemistry at all the identified points is presented in great detail using the above-mentioned analyses and illustrations. This work highlights the possibility of combining a high-fidelity simulation and a simple 0D ideal reactor to decipher the nuances of NO chemical pathways in a practical swirl-stabilised gas turbine combustor and provide new understanding for assisting engineers in designing clean burners.

Continuous-Flow Synthesis of Zn1-xMnxS Nanoparticles at Ambient Conditions.

With its large direct band gap and good chemical stability, ZnS is suitable for many applications, including light-emitting diodes, panel displays, and photodetection. Here, nanoparticles of ZnS are synthesized phase pure under ambient conditions by precipitation in a simple and scalable continuous-flow reactor. Furthermore, different degrees of Zn substitution with Mn have been investigated, Zn1-xMnxS, with x = 0.05, 0.19, and 0.25 according to X-ray fluorescence measurements. The products are analyzed with multitemperature synchrotron powder X-ray diffraction (PXRD) and X-ray total scattering. The analysis reveals phase-pure synthesis products with the sphalerite structure and crystallite sizes in the range of 3.8-4.7 nm in agreement with scanning transmission electron microscopy. Only Zn0.75Mn0.25S shows traces of Mn3O4, indicating that x = 0.25 is above the substitution limit as the impurity appears. Substitution of Zn with Mn in the nanoparticles is confirmed by energy-dispersive X-ray spectroscopy, as well as an observed decrease in the band gap, decrease in the sphalerite-to-wurtzite phase transition temperature, and increase in the unit cell dimensions with increasing Mn content. Based on the modeling of the PXRD Rietveld refined atomic displacement parameters, the Debye temperature for ZnS and Zn0.95Mn0.05S is determined to be 322 ± 13 and 394 ± 22 K, respectively.

Integration of Full-Size Graywater Membrane-Aerated Biological Reactor with Reverse Osmosis System for Space-Based Wastewater Treatment.

To date, life support systems on the International Space Center (ISS) or those planned for upcoming moon/Mars missions have not included biological reactors for wastewater treatment, despite their ubiquitous use for the treatment of terrestrial wastewaters. However, the new focus on partial gravity habitats reduces the required complexity of treatment systems compared with those operating in micro-gravity, and the likely addition of large-volume wastewaters with surfactant loads (e.g., laundry and shower) makes the current ISS wastewater treatment system inappropriate due to the foaming potential from surfactants, increased consumable requirements due to the use of non-regenerative systems (e.g., mixed adsorbent beds), the complexity of the system, and sensitivity to failures from precipitation and/or biological fouling. Hybrid systems that combine simple biological reactors with desalination (e.g., Reverse Osmosis (RO)) could reduce system and consumable mass and complexity. Our objective was to evaluate a system composed of a membrane-aerated bioreactor (MABR) coupled to a low-pressure commercial RO system to process partial gravity habitat wastewater. The MABR was able to serve as the only wastewater collection tank (variable volume), receiving all wastewaters as they were produced. The MABR treated more than 20,750 L of graywater and was able to remove more than 90% of dissolved organic carbon (DOC), producing an effluent with DOC < 14 mg/L and BOD < 12 mg/L and oxidizing >90% of the ammoniacal nitrogen into NOx-. A single RO membrane (260 g) was able to process >3000 L of MABR effluent and produced a RO permeate with DOC < 5 mg/L, TN < 2 mg/L, and TDS < 10 mg/L, which would essentially meet ISS potable water standards after disinfection. The system has an un-optimized mass and volume of 128.5 kg. Consumables include oxygen (~4 g/crew-day), RO membranes, and a prefilter (1.7 g/crew-day). For a one-year mission with four crew, the total system + consumable mass are ~141 kg, which would produce ~15,150 kg of treated water, resulting in a pay-back period of 13.4 days (3.35 days for a crew of four). Given that the MABR in this study operated for 500 days, while in previous studies, similar systems operated for more than 3 years, the total system costs would be exceedingly low. These results highlight the potential application of hybrid treatment systems for space habitats, which may also have a direct application to terrestrial applications where source-separated systems are employed.

Design and Study of Simple Biogas Reactor using Kitchen Waste Within the Habitat of Federal Polytechnic of Oil and Gas Bonny Island, Rivers State, Nigeria

This research work is about design and study of simple biogas reactor using Kitchen Waste within the habitat of Federal Polytechnic of Oil and Gas Bonny Island, Rivers State, Nigeria to produce gas. The objective of the work is to collect and measure the amount of waste that is been generated within the study area as well as to construct a simple laboratory scale biogas reactor and using the kitchen waste as substrate and measure the amount of gas that is been generated from biogas reactor per day. Based on the objective for this research a biogas digester was designed. Two experiments was carried out to determine the extent of production of biogas and the duration required so as to determine the rate of formation of biogas. In experiment one, dissimilar kinds of biomass like rice, potato, green leaves, sugar in different amounts were mixed with cow dung and rice husk to prepare 4 samples to determine the maximum generation of biogas through fermentation process. The gas is collected in balloons and they were measured to determine the amount of gas produced in each sample. The extent to which the blowing of balloons took place determined the quantity of gas evolved in each of the incumbent samples. In experiment two, we have used two 5lt. bottles in which the amount of cow dung used varies while same amount of kitchen waste mixture was utilized. The process and conditions for trapping and analyzing the gas is the same as in experiment one. From this experiment the rapidness of formation of biogas was observed. The experimental analysis carried out also gives us a clear idea of the indulgence of materials with respect to their combination to deferring extent of concentration to deliver optimum generation of biogas, in particular methane thereby unveiling us to develop an imminent and high performance derivative affordable biogas reactor.

Photocatalytic degradation of paracetamol on immobilized TiO2 in a low-tech reactor by solar light for water treatment

Photocatalytic water treatment is an appealing concept to mineralize organic contaminants in contaminated water. In this study, the UV-resistant drug paracetamol (PCT) in aqueous solution is degraded by using a solar irradiated loop-reactor equipped with a TiO2 (P25) photocatalyst. The catalyst powder was dispersed in a geopolymer surface coating applied to aluminum-U-profiles connected by filament-printed polymer elements. Different assays with variations in initial PCT concentration were performed under natural solar radiation to determine the degradation kinetics of the PCT and correlate it to applied solar radiation energy density. Depending on experimental conditions, degradation efficiencies of 37.0–75.1 % were achieved within 3 h. Control samples without catalyst show no degradation. No degradation of the catalyst activity was observed within 42 h of operation time. The study shows the feasibility of this simple and scalable reactor design and coating technology for water purification under off-grid conditions provided sufficient solar radiation is available.

Evaluation of the impacts of seawater integration to electrocoagulation for the removal of pollutants from textile wastewater

Recent textile industry expansion has a major environmental impact if not addressed. Being a water intensive industry, textile manufacturing is usually associated with wastewater management challenges. Electrocoagulation (EC) is recognized as one of the effective solutions to address these challenges. This study aims to investigate the potential of integrating seawater into the EC process for textile wastewater treatment, targeting optimal pollutant removal efficiencies. A simple electrolytic reactor was designed to investigate the removal efficiency of these treatments for chemical oxygen demand (COD), total suspended solids (TSS), turbidity, and color from textile wastewater at different seawater percentages and retention times. Notably, the addition of seawater not only improves the EC process efficiency but also significantly dilutes pollutants, reducing their concentrations. This dual effect enhances removal efficiency and dilution optimizes the treatment outcome. The highest removal efficiencies were achieved for COD (47.26%), TSS (99.52%), turbidity (99.30%), and color (98.19%). However, pH, dissolved oxygen (DO), and electrical conductivity increased with increasing retention times and seawater percentages in the EC process. Moreover, Seawater − EC integration reduces power usage to 15.769 Am−2 and costs approximately 0.20 USD/m3. To assess the effects of the retention times and seawater percentages on pollutant removal from textile wastewater, an analysis of variance (ANOVA) was conducted utilizing the Design-Expert 11 software. The best model obtained using Central Composite Design (CCD) was quadratic for COD (R2 = 0.9121), color (R2 = 0.9535), turbidity (R2 = 0.9525), and TSS (R2 = 0.9433). This study suggests that higher seawater percentages and longer retention times effectively eliminate contaminants but increase ion concentrations.

Development of SynBio Tools for Pseudomonas chlororaphis: A Versatile Non-Pathogenic Bacterium Host

Pseudomonas chlororaphis ATCC 9446 is a non-pathogenic bacterium associated with the rhizosphere. It is commonly used as a biocontrol agent against agricultural pests. This organism can grow on a variety of carbon sources, has a robust secondary metabolism, and produces secondary metabolites with antimicrobial properties. This makes it an alternative host organism for synthetic biology applications. However, as a novel host there is a need for well-characterized molecular tools that allow fine control of gene expression and exploration of its metabolic potential. In this work we developed and characterized expression vectors for P. chlororaphis. We used two different promoters: the exogenously induced lac-IPTG promoter, and LuxR-C6-AHL, which we evaluated for its auto-inducible capacities, as well as using an external addition of C6-AHL. The expression response of these vectors to the inducer concentration was characterized by detecting a reporter fluorescent protein (YFP: yellow fluorescent protein). Furthermore, the violacein production operon was evaluated as a model heterologous pathway. We tested violacein production in shake flasks and a 3 L fermenter, showing that P. chlororaphis possesses a vigorous aromatic amino acid metabolism and was able to produce 1 g/L of violacein in a simple batch reactor experiment with minimal medium using only glucose as the carbon source. We compared the experimental results with the predictions of a modified genome scale model. The presented results show the potential of P. chlororaphis as a novel host organism for synthetic biology applications.

Assessing Cu2+ active sites evolution on Cu-SSZ-13 NH3-SCR catalysts during hydrothermal aging: A transient response approach

Hydrothermal aging (HTA) conditions are commonly reached in Diesel engine NH3-SCR architectures based on Cu-CHA catalysts, altering the catalyst performance due to irreversible transformations of the catalytic sites. Relying on transient response methods (TRMs), we study two Cu-SSZ-13 samples with different HTA extents. The following conclusions apply: i) the Cu2+content is invariant with HTA; ii) the ZCu2+(OH)- population decreases concurrent to the increase of the Z2Cu2+ fraction and to iii) the loss of Brønsted acidity. This evidence agrees with the simple stoichiometry proposed for mild HTA processes: ZCu2+(OH)-+ZH+→Z2Cu2++H2O. Furthermore, TRMs permit to observe additional phenomena which comply with a low-T Cu2+-pair mediated reduction pathway recently proposed. The results from a comprehensive set of simple experimental flow reactor methods consolidate the proposed aging mechanism, strengthen the SCR reduction half cycle (RHC) mechanistic understanding and showcase TRMs as a viable alternative to more complex techniques for the characterization of Cu-CHA catalysts.

Simplified Reactor Model for Microreactor Coupled with Helium Closed Brayton Cycle

Microreactors comprise a new actively developing class of very small advanced reactors that have the potential to be an alternative to carbon-intensive energy technologies. A microreactor based on high-temperature gas reactor (HTGR) technology is a very promising advanced reactor with inherent safety, and it can couple with a closed Brayton cycle for higher efficiency. Since dynamics characteristics are fundamental to analyzing a power generation system and a reactor is the main source of the dynamics characteristics of a system, it is necessary to study a microreactor model suitable for system analysis. The main goal is to simulate the performance of the previously mentioned integrated system, focusing on the details of the power conversion unit while still ensuring acceptable calculation times. Hence, a simplified reactor model is needed that could supply sufficiently accurate values of pressure drop and heat transfer across the core. In this paper, by simplifying the physical processes in a microreactor, a dynamic model described by differential algebraic equations is obtained based on the lumped parameter modeling methodology and the basic conservation of fluid mass, momentum, and energy. Coupling thermal hydraulics with neutron kinetics, the temperature coefficient of reactivity and xenon poisoning are considered. Finally, the model is programmed and calculated using Modelica language. The transient responses of the main parameters under typical perturbations are analyzed, and the results show that the responses are correct. Because of the effect of reactivity feedback, fluctuations of the main parameters caused by microperturbations eventually tend to stabilize. In addition, the effects of negative reactivity introduced by xenon poisoning under two typical dynamic processes are analyzed. In power regulation, excess reactivity is required to compensate for the negative reactivity introduced by 135Xe. The model and results can properly predict the systematic parameters and serve as a basis for system analysis of microreactor coupling with the helium closed Brayton cycle.

Comparison of Waste Biomass from Pine, Eucalyptus, and Acacia and the Biochar Elaborated Using Pyrolysis in a Simple Double Chamber Biomass Reactor

Using waste biomass is considered one of the ways to reduce climate change. Arboreal waste biomass from pine, eucalyptus, and particularly invasive plants (Acacias) would make it possible to transform this natural resource, but needs to be adjusted to current and innovative technologies. The production of high fixed carbon biochar with this biomass would improve not only environmental aspects, but also the use of currently not susceptible materials for other types of exploitation. The objective of this study is to develop biochar from three different waste biomass materials and compare their parameters with those of the original biomass. Thermochemical conversion processes were used in a simple double chamber reactor developed for this study. Temperatures between 400 and 500 °C during 280 min were achieved and allowed to transform the initial biomass in a biochar with a high content of fixed carbon. By comparing the original biomass with the final biochar through tests of humidity, density, calorific values, fixed carbon, and cationic and elemental analysis, an increase in the parameters was confirmed. Fixed carbon of 70%, 77%, and 71% with pine, acacia, and eucalyptus biomass have been obtained, respectively, with yields between 30% and 40%. The results are favorable, particularly with acacia invasive plants, and could help in their difficult silviculture management.

Computational Design of Optimized Modular Photovoltaic Electrochemical Reactor for Energy Efficient CO2‐to‐Cn Reduction Reaction with Bandgap Tunable Perovskite Tandem Cells

AbstractFor electrosynthesis of carbon fuels from CO2, engineered catalysts have improved the electrochemical (EC) reduction efficiency. However, most EC systems rely on a batch reactor, which is not relevant for Cn fuels with high n (n ≥ 3) due to low selectivity. For enhanced electron‐to‐fuel (ETF) efficiency, modular configurations are advantageous. The best configurations allowing high yield reduction of CO2 into Cn fuels are investigated. It is found that serial and parallel configurations exhibit four to five times higher ETF efficiency than simple batch reactor. The best photovoltaic (PV) tandem cells made of metal halide perovskite for the optimized EC modular systems are also found. These materials have a bandgap tunability covering most Cn fuels. With the computationally optimized tandem PVs, it is found that the [PV+EC] series configuration achieves up to 2.28% and 2.86% solar‐to‐fuel (STF) efficiency of C3 aldehydes and alcohols, which are greater than what has been reported in the literature. For C4 aldehydes and alcohols, the [PV+EC] parallel configuration achieves up to 0.17% and 0.21% STF efficiency, respectively. The present study on modules and materials design will provide a useful way to create EC production of Cn fuels that can help reach carbon neutrality.

A Data-Based Hybrid Chemistry Acceleration Framework for the Low-Temperature Oxidation of Complex Fuels

The oxidation of complex hydrocarbons is a computationally expensive process involving detailed mechanisms with hundreds of chemical species and thousands of reactions. For low-temperature oxidation, an accurate account of the fuel-specific species is required to correctly describe the pyrolysis stage of oxidation. In this study, we develop a hybrid chemistry framework to model and accelerate the low-temperature oxidation of complex hydrocarbon fuels. The framework is based on a selection of representative species that capture the different stages of ignition, heat release, and final products. These species are selected using a two-step principal component analysis of the reaction rates of simulation data. Artificial neural networks (ANNs) are used to model the source terms of the representative species during the pyrolysis stage up to the transition time. This ANN-based model is coupled with C0–C4 foundational chemistry, which is used to model the remaining species up to the transition time and all species beyond the transition time. Coupled with the USC II mechanism as foundational chemistry, this framework is demonstrated using simple reactor homogeneous chemistry and perfectly stirred reactor (PSR) calculations for n-heptane oxidation over a range of composition and thermodynamic conditions. The hybrid chemistry framework accurately captures correct physical behavior and reproduces the results obtained using detailed chemistry at a fraction of the computational cost.

Extraction of the intrinsic rate constant for a photocyclization reaction in capillary microreactors using a simplified reactor model

Extraction of the intrinsic rate constants for a photocyclization reaction from a simplified reactor model.

Proposal of Application of a Simple Analysis Code DYMOS for Accident Analyses of Molten Salt Reactors

The Molten Salt Reactor (MSR) possesses unique characteristics, including the circulation of liquid fuel salt in-core and ex-core, and the absence of cladding tubes of fuel rods. To perform safety analyses for accidents and transients, the selection of appropriate models is crucial. Proposed models vary from the coupling of a three-dimensional (3-D) nuclear reactor model and a detailed thermal/hydraulic (T/H) model to a simple point reactor model coupled with a lumped parameter model of the T/H system. The authors have been investigating the development of a simple and accurate model that can be utilized during the design stage and licensing evaluation, while also providing transparency, which means that models can be easily understandable by experts and reproduced in licensing evaluation. Given the distinctive features of the MSR, the peak heat flux or fuel cladding peak temperature is not a requirement. Instead, the most decisive parameter for safety evaluations is the fuel salt temperature in the fuel salt boundary. As demonstrated in this paper, the outlet of the MSR core consistently displays the highest temperature.Based on the afore-mentioned prospects for both nuclear and T/H systems, the authors have developed a simple safety and transient analysis code for MSR (DYMOS). The DYMOS code has been verified for MSRE experiments, as described in this paper. However, the previous verification was limited to small experimental MSRs, and there is a lack of verification for large reactor systems. This paper shows that the DYMOS code is applicable to these larger reactors. In other words, the main objective of this article is not to claim the originality of the model of DYMOS code, but to propose applicability of such simple code to large reactor systems.

CFD modeling and simulation of benzyl alcohol oxidation coupled with hydrogen production in a continuous-flow photoelectrochemical reactor

Various conversion routes of biomass and its derivative compounds into high-value products has attracted attention from researchers recently. Among these, a solar-driven photoelectrochemical (PEC) oxidation approach of biomass alcohols to aldehydes is particularly of great interest for the potential applications because the reaction is selective and simultaneously accompanied with hydrogen production. Here, we propose a simulation of selective oxidation of benzyl alcohol into benzaldehyde coupled with hydrogen production in a 2-dimensional continuous-flow PEC reactor using COMSOL Multiphysics (5.6). In order to develop and fabricate a simple yet efficient reactor for a practical use, it is crucial to investigate the effects of operating and design parameters of the reactor on the reactions. Our studies demonstrated that the main contributions to product formation were the electrolyte flow velocity and the width of electrolyte channels. The optimized design parameter exhibited good photoelectrochemical performance with uniform potential distribution within the channels which served diffusion of neutral and charged species and electrochemical reaction. The maximum conversion of benzyl alcohol in this work was 48.25% with 100% selectivity of benzaldehyde. These findings are key for the design of the continuous-flow PEC reactor that can be applied to any series of biomass conversion reactions under mild conditions.

Acoustofluidics-assisted strategy of zinc oxide nanoarrays for enhancement of phase-change chip cooling

Enhancing flow boiling in microchannel via surface modification is crucial for addressing the energy consumption challenges posed by high-power compact electronic devices. However, improving boiling heat transfer performance with well-defined nanostructured surfaces in a limited space remains a challenge. Herein, we present a simple and straightforward acoustofluidics strategy for stable, controllable, and efficient fabricates of functional Zinc oxide (ZnO) nanoarray silicon chip surface with excellent phase change cooling performance. The intentionally designed flower-like sharp-edge structure integrated acoustic has been experimentally and numerically verified for its enhanced mass transfer mixing. The resulting ZnO nanoarray-coated chip with customizable lengths, densities, and morphology is implemented by simple reactor parameter adjustment. Excellent boiling heat transfer performance is obtained on this surface, giving priority to nucleation (superheat≈ 4 °C), low energy consumption (≤3.2 kPa) and simultaneously enhancing the critical heat flux (CHF) and heat-transfer coefficient (HTC) by up to 70.8 % and 107.5 %, respectively, compared with a smooth chip surface. In situ observation and analysis of the wicking of the nanoarray and nucleation, growth, and departure of the bubbles reflect that ZnO nanoarray promotes the phase change heat exchange process by the large number of nucleation sites and ultrafast liquid re-wetting. These findings not only provide important guidelines for the precise control and rational design of functional nanomaterials, but also provide new insights for embedded cooling and significant energy savings on power devices.

Estimation of weight window parameters based on recursive Monte Carlo approach for reactor shielding problems

Weight window, a variance reduction tool, is often used to improve the performance of radiation shielding calculations. One common issue with the weight window is determining the optimal set of weight window parameters for solving deep penetration shielding problems. To address this issue, the recursive Monte-Carlo methodology has been used with the in-house TRAWEI code. The program is responsible for generating the optimal weight parameters in a single run with minimum computational time. This paper presents the results of a numerical test conducted using a simple reactor model to evaluate the performance of the developed weight generator program. The findings reveal that MCNP simulations utilizing TRAWEI-generated weight values exhibit significantly higher calculation efficiency compared to both analog simulation and MCNP simulation using weights generated by the existing MCNP weight window generator. Overall, the utilization of the RMC methodology has shown its potential to significantly contribute to deep penetration shielding calculations.

ВВЭР-1000 ЯДРОЛЫҚ РЕАКТОРЫНДАҒЫ ЖЫЛУФИЗИКАЛЫҚ ПРОЦЕСТЕРДІ КОМПЬЮТЕРЛІК МОДЕЛЬДЕУ

The priority use of water-water reactors in the nuclear power industry is due to their advantages. Water is ideally suited as a moderator and refrigerant, providing compactness, high power and simple reactor design. Water-water reactors have high resistance and self-regulation due to the negative temperature coefficient of reactivity. Their activity is caused by short-lived nuclides, which facilitates biological protection and access to equipment. Water effectively removes heat. However, there are also disadvantages: high neutron absorption by water, the requirement of uniform distribution of water, corrosion activity, expensive cleaning system and temperature limitation. An increase in unit power is possible due to the equalization of heat generation in the core. This requires an accurate thermohydraulic calculation. As a result of the study, a theoretical thermohydraulic calculation of heat transfer in the heat - generating set of the VVER-1000 reactor was obtained for the weighted average and maximum values of heat release in the heat-generating set. Computer simulation of heat transfer was also carried out for the distribution of moderately loaded energy in the heat-generating set. The results obtained were compared and analyzed. As a result of the calculation, the distribution graph and temperature field of the heat-releasing element of the coolant, fuel and reactor in the shell of the VVER-1000 heat-releasing kit were obtained.

Simple single reactor synthesis of nickel (II)-cobalt (II) ferrite composites with biochar and their photocatalytic properties

The paper proposes a simple one-stage synthesis of ferrite/biochar composites based on oxide compounds of NixCo1-xFe2O4 (х = 0, 0.5, and 1). The obtained materials were characterised using x-ray diffraction patterns, Fourier transform infrared (FTIR) spectrometry, electron microscopy, Scherrer and Williamson-Hall methods. The high photocatalytic activity of the synthesised materials in the process of methyl orange oxidative degradation at hydrogen peroxide presence has been established. It is noted that the highest catalytic activity is exhibited by the composite material based on cobalt (II) ferrite and sunflower biochar: in their presence, it is possible to achieve 100% removal of the dye after 120 and 90 min, respectively. A possible mechanism of the dye decomposition process is discussed.