Reactor Design Studies Research Articles

GX: a GPU-native gyrokinetic turbulence code for tokamak and stellarator design

GX is a code designed to solve the nonlinear gyrokinetic system for low-frequency turbulence in magnetized plasmas, particularly tokamaks and stellarators. In GX, our primary motivation and target is a fast gyrokinetic solver that can be used for fusion reactor design and optimization along with wide-ranging physics exploration. This has led to several code and algorithm design decisions, specifically chosen to prioritize time to solution. First, we have used a discretization algorithm that is pseudospectral in the entire phase space, including a Laguerre–Hermite pseudospectral formulation of velocity space, which allows for smooth interpolation between coarse gyrofluid-like resolutions and finer conventional gyrokinetic resolutions and efficient evaluation of a model collision operator. Additionally, we have built GX to natively target graphics processors (GPUs), which are among the fastest computational platforms available today. Finally, we have taken advantage of the reactor-relevant limit of small $\rho _*$ by using the radially local flux-tube approach. In this paper we present details about the gyrokinetic system and the numerical algorithms used in GX to solve the system. We then present several numerical benchmarks against established gyrokinetic codes in both tokamak and stellarator magnetic geometries to verify that GX correctly simulates gyrokinetic turbulence in the small $\rho _*$ limit. Moreover, we show that the convergence properties of the Laguerre–Hermite spectral velocity formulation are quite favourable for nonlinear problems of interest. Coupled with GPU acceleration, which we also investigate with scaling studies, this enables GX to be able to produce useful turbulence simulations in minutes on one (or a few) GPUs and higher fidelity results in a few hours using several GPUs. GX is open-source software that is ready for fusion reactor design studies.

Design of Reactor for The Production of PbO Particles

The aim of this study was to design and analyze the batch reactor designs to produce PbO particles on an industrial scale. The method used in this research is to perform computational analysis and calculation of the reactor and its stirrer as well as the mass balance as the basis for calculations using the Microsoft Excel application. The study of reactor design is one of the key steps of a process design in industry, and these specifications are used as a reference in production costs. To produce PbO particles on an industrial scale (10,000× laboratory scale), are required two reactors and two stirrers. The calculation results show that the first reactor has a volume of 11.2334 ft3 with a height of 3.2219 ft and requires one stirrer with a power of 163 Hp, while the second reactor has a volume of 7.3576 ft3 with a height of 11.9503 ft and requires one stirrer with power 191 Hp. The results of this computation and analysis can be applied to the design and analysis of reactor performance as a learning medium and operating mechanism in a production system.

Continuum modeling of high-temperature (>1000 °C) heat extraction from a moving-bed oxidation reactor for thermochemical energy storage

There is a growing need for efficient and reliable energy storage technologies to expand renewable energy adoption and transit to a decarbonized clean energy future. Thermochemical energy storage (TCES) through reversible gas-solid reactions has exhibited considerable potential. Up to now, TCES has primarily been studied at the material level and within lab-scale reactors. As such, accurate numerical models are needed for further reactor design and scale-up. In this work, a transient three-dimensional heat and mass transfer continuum model was developed to simulate the transport phenomena coupled with exothermic oxidation of magnesium‑manganese-oxide particles in a high-temperature moving-bed reactor for TCES. The reactor included direct heat extraction at temperatures >1000 °C. The predicted temperature distributions, oxygen concentration profiles, and steady-state reactor energy extraction efficiency were in good agreement with measured values from a corresponding experimental setup. The performance of the reactor was further investigated through two parametric studies (varied particle flow rates and gas extraction ratios), which demonstrated a strong dependence of reactor efficiency (varied between 15 %–40 %) on both operating parameters. The present heat and mass transfer model will be valuable in further reactor design and scale-up studies, as well as for selection of operating conditions to maximize efficiency.

Oxidative coupling of biogas to ethylene over a trilobe-shaped Mn-Na2WO4/α-Al2O3 catalyst in a single-pellet reactor

Despite the development of selective catalyst formulations for oxidative coupling of methane (OCM), kinetic and reactor design studies have been hampered by a lack of data for truly isothermal reaction conditions. Because of the high exothermicity, the temperature of a fixed-bed reactor filled with Mn-Na2WO4/SiO2 catalysts will show hot-spots with a loss of selectivity. The objective of this study is to measure catalyst activity under relevant reaction conditions of pressure (3 bar), biogas composition (no dilution) and contact time, while keeping the process isothermal. To this aim, we have synthesized and shaped a trilobed Mn-Na2WO4/α-Al2O3 catalyst, which may be used as is at industrial scale, and measured its performance in a single-pellet reactor. We found that the presence of CO2 did not degrade the catalyst performance, even on the long run, which should enable the use of a CO2-rich stream such as biogas. Actually, higher methane conversions have been obtained in the presence of CO2, likely due to a possible contribution of methane dry reforming reaction. We also noticed a slow catalyst activation over the first 100 h, while selectivity was kept constant.

Reactor design and numerical study on metal hydride based finned reactor configurations for hydrogen compression application

The present study is focussed on the design and development of a single stage metal hydride hydrogen compressor. A 0.5 kg alloy mass capacity reactor is designed to withstand 100 bar at 120 °C. The Von Misses equivalent stress is calculated for the designed reactor and it is found to have a design margin of 11.4%. The reactor has an excellent weight ratio of 2.22. To enhance the thermal performance of the reactor, extended surfaces are incorporated. A numerical model is developed to compare the performance of three different fin configurations namely longitudinal fins, transverse fins and spiral fins. Longitudinal fins are found to provide better thermal enhancement during initial period of absorption half cycle. However, transverse fins showed better performance in the desorption case. Nevertheless, as the time progresses all the fin configurations showed similar performance under different operating temperatures. Further, hydrogen discharge rate is studied at various discharge pressure to understand the requirements while coupling with an empty cylinder or fuel cell. The study revealed that a 0.5 kg reactor can discharge hydrogen at the rate of 2.27 lpm for 2000 s when discharged to fill a cylinder up to 10 bar. The compression rate of the developed compressor is found to be 136 l/h at 10 bar discharge pressure and 373 K heat source temperature. The isentropic efficiency of the compressor is found to be 11.5%.

Steam Methane Reforming with Chemical-Looping Combustion: Scaling of Fluidized-Bed-Heated Reformer Tubes

The combination of chemical-looping combustion (CLC) and steam methane reforming (SMR) bears the potential for quantitative and energy-efficient CO2 capture along with hydrogen production from natural gas. A 2-dimensional axisymmetric model of a SMR tube was used to estimate the possibility to adapt the tube dimensions to better fit into fluidized-bed heat exchangers. A constant surrounding fluidized-bed temperature was set as the boundary condition. There are two phenomena that affect the reactor performance: the effective heat-transfer rate from the fluidized bed to and through the tube wall and onward to and into the catalyst bed on the one hand and the effective reaction rates of the governing chemical reactions on the other hand. Literature models were used for the heat-transfer description assuming a state-of-the-art reforming catalyst and classical SMR kinetics were formulated. The simulation results show a temperature decrease toward the tube center in steady state operation. The gas phase composition at the tube outlet reflects the radial temperature distribution as the chemical equilibrium is approached well. Simulations with smaller tube diameters indicate that the necessary tube length for equivalent gas conversion is significantly reduced. In a 1/2-scale setting with 63 mm inner diameter (ID) of the tube instead of 126 mm ID in full scale, the necessary tube length is only 6.0 m instead of 12.5 m, and in a 1/4-scale setting with 31.5 mm ID, the necessary tube length is only 3.3 m. A temperature increase of the fluidized bed from 900 to 950 and 1000 °C may reduce the necessary tube length in the 1/4 scale from 3.3 to 2.6 and 2.2 m, respectively. These indications are promising with respect to the possibilities for fluidized-bed immersed reformer tube dimensioning and arrangement. More detailed reactor design studies will be necessary to judge the industrial feasibility of the CLC-SMR combination.

Coupling reactor design and scenario calculations: a promising method for scenario optimization

The link between reactor design studies and scenarios calculations is usually sequential. From a list set of objectives, a reactor design is produced and passed to the scenarist in the form of a numeric irradiation model. This approach assumes that the reactor design is fixed from the scenarist perspective. The method presented in this article proposes to use a flexible reactor model, built with artificial neural networks, that gives the possibility to the scenarist to change a reactor design directly during the scenario calculations. Doing so, the reactor design is no longer an imposed parameter but a tool to find new optimal trajectories. Moreover, this flexible model is able to exploit the historical loaded fuel compositions generated by the scenario calculations in order to monitor the reactor performances over time. In this paper, the flexible reactor model construction is detailed and the interest of such method is highlighted with an application case that consists in the transition from a PWR fleet, similar to the French one, towards a PWR − SFR fleet stabilizing plutonium inventory.

AUTOMATED FUEL DESIGN OPTIMIZATION FOR HIGH FLUX ISOTOPE REACTOR LOW ENRICHED URANIUM CORE DESIGN

The low enriched uranium (LEU) conversion project for the High Flux Isotope Reactor (HFIR) requires that the converted core design perform as well as or better than the current high enriched uranium core design with respect to key performance metrics, such as isotope production, while maintaining sufficient safety margins. Various designs and fuel shapes have been explored in previous optimization studies. A suite of scripts has been developed for HFIR LEU design and analysis to simplify the reactor physics and thermal hydraulics (TH) analyses. The scripts include generating a high-fidelity 3D HFIR model to perform core depletion simulations with the SHIFT Monte Carlo code, performing an essential rod criticality search during depletion, parsing SHIFT output to determine HFIR key metrics, and performing TH analysis with the HFIR Steady-State Heat Transfer Code. Previously, these scripts were separated and required human interaction between simulation stages. These scripts have been modernized and integrated into a single Python package (the Python HFIR Analysis and Measurement Engine or PHAME) to streamline execution and avoid potential human error. After modernizing the suite of scripts into a single, automated workflow, the tool set was wrapped into an in-house metaheuristic optimization driver that enables different optimization methods, such as simulated annealing and particle swarm. The optimization driver samples a fuel shape, runs PHAME, calculates the cost function with the metrics returned from PHAME, and repeats those steps until it finds an optimal fuel shape. This work demonstrates the workflow of a comprehensive, automated reactor design study and how metaheuristic optimization methods can be leveraged to fine-tune a design parameter like fuel shape. This workflow of wrapping an optimization driver on a full-scale reactor analysis suite increases design and analysis efficiency.

Plasma composition control by mixture pellets at ASDEX Upgrade

Experiments were performed that aimed to control the plasma isotopic mixture by delivering supplemental components into the plasma via pellet injection. Pellets, mm-sized solid bodies of frozen fuel, are either formed from a mixture of different hydrogen isotopes or from deuterium (D) with added elements. Mixed HD pellets were produced reliably and reproducibly providing the required 1:1 ratio of the protium (H) and D, mimicking the situation in a future fusion reactor with D and tritium (T). By applying pellet fuelling, control of the plasma isotope composition was established while gaining access to the reactor-relevant high-density regime. However, the approach was mainly to demonstrate the controlling capability. Yet, experiments provided information on the impact of the isotopic composition on the plasma performance. There is a strong indication that adding H to a D reference plasma causes a reduction of both the particle and energy confinement. The deleterious impact of H on the particle confinement is, apparently, even stronger than on the energy confinement. Furthermore, small amounts of H can cause a loss of energy confinement that is stronger than anticipated by the H98(y,2) scaling, which is usually employed in reactor design studies. In the course of this experiment, pellets were demonstrated to be an effective and powerful tool for detailed investigations of the isotope effect. A first test demonstrated that producing and launching pellets that contain a mixture of different elements is a feasible technique. The latter was achieved by doping a D host pellet despite technical reasons limiting the permissible amount of processed N.

Effect of lift force and hydrodynamic torque on fluidisation of non-spherical particles

The aim of many industrial processes is to manipulate solid particle aggregates within gas suspensions. Prime examples of such processes include fluidised bed reactors, cyclone separators, and dust collectors. In recent years, fluidised bed reactors have been used in the gasification of biomass particles. When fluidised, these particles are subject to various hydrodynamic forces such as drag, lift and torque due to interactions with the fluid. Computational approaches, which can be used to replicate laboratory and industrial scale processes, offer a crucial method for the study of reactor design and for the formulation of optimal operating procedures. Until now, many computer models have assumed particles to be spherical whereas, in reality, biomass feedstocks typically consist of non-spherical particles. While lift and torque are of minimal importance for spherical particles, non-spherical particles experience varying lift force and torque conditions, depending on particle orientation relative to the direction of the fluid velocity. In this study, we present a numerical investigation on the effect of different lift force and torque correlations on fluidised spherocylindrical particles. We find that lift force has a significant influence on particle velocities parallel to the direction of gravity. On the other hand, particle orientation is dependent on hydrodynamic torque. Results from this numerical study provide new insight with regards to the dynamics of non-spherical particles that can be of paramount importance for industrial processes involving non-spherical particles.

Reactor Design and Kinetic Study on Adsorption/Desorption of CO and Cl2 for Industrial Phosgene Synthesis

AbstractThe aim of this work is the utilization of carbon monoxide (CO) from steel mill gases for the synthesis of phosgene, which can further react with phenol to building blocks for polymers. The effect of impurities like NOx, CO2, and O2 on the activity and stability of the activated‐carbon (AC) catalyst and the follow‐up products should be evaluated. Therefore, new porous carbon catalysts and a new reactor are designed for a systematic kinetic study on the adsorption and desorption behaviors of CO and chlorine (Cl2) on carbon‐based materials to identify AC catalysts with optimum physical properties.

Modeling of a square channel monolith reactor for methane steam reforming

This work comprises the systematic study of a monolithic reactor design for steam methane reforming (SMR) to achieve optimal dimensions for the highest rate of reaction. The design is developed using an analytical model to establish the optimum length of the reactor. The result is confirmed by a computational fluid dynamics (CFD) model. Experimental work on SMR is carried out in lab scale. In the analytical models, the design equations for the square channel reactor are derived to estimate the channel length that affords the highest rate of reaction. The optimum length is determined as 41.6 mm with a reaction rate of 2.88 × 10−8 mol/s at the channel height of 1.5 mm, 873 K, and 1 atm. The respective optimum channel length from the CFD and experimental results are 80.0 mm and 90.0 mm, respectively, with respective reaction rates of 7.42 × 10−7 mol/s and 6.85 × 10−7 mol/s. The effects of channel heights ranging from 0.5 to 3.0 mm are investigated by CFD. Methane conversion per unit channel perimeter is defined as a design parameter for the sizing and rating of this platform. The highest value (50% mm−1) is afforded at a channel height of 0.50 mm.

Combined Effects of Ionic Liquid and Tungsten–Halogen Radiation on Heterogeneous Hydrolysis Kinetics of Waste Papaya Epidermis for Production of Total Reducing Sugar

This article reports on optimization and kinetic modeling of Amberlyst-36 heterogeneous catalytic hydrolysis of papaya (Carica Papaya) epidermis (PE) in conjunction with ionic liquid (1-butyl-3-methylimidazolium chloride, [BMIM]Cl) for total reducing sugar (TRS) production. The intensification effects in presence of tungsten–halogen radiator (THR) on sequential pretreatment and hydrolysis have been optimized. In pretreatment and hydrolysis, the optimized factors were 70 and 80 °C reactor temperature, 20 and 10 min batch time, water to PE ratio (w/w) of 5 and 20 respectively. An optimum 2.5 (w/w) NH4OH loading in pretreatment while 7.5 wt% catalyst concentration and 20 (w/w) [BMIM]Cl loading in hydrolysis using the tungsten–halogen radiated reactor (THRR) yielded maximum 89.02 mol% TRS which was significantly greater than that obtained (37.41 mol%) through the conventionally heated reactor (CHR). Eley–Rideal mechanism best fitted the hydrolysis kinetics while pseudo-homogeneous model could best represent pretreatment kinetics. Remarkably, the larger activation energy (69.02 kJ/mol) in CHR in comparison with THRR evidently established the greater energy-efficiency of the THRR system. The evaluated kinetic parameters can be useful for reactor design and scale-up studies. The developed energy-efficient, green hydrolysis for optimum TRS synthesis from papaya epidermis also provides sustainable valorization of similar lignocellulosic biomass waste.

Fluidized bed reactor design study for pressurized chemical looping combustion of natural gas

Chemical looping combustion (CLC) is considered a viable option for efficient power production with inherent carbon sequestration through an unmixed combustion process. Pressurized reactor systems promise the potential for increased efficiency compared to atmospheric processes because gas turbine technology can be used in a combined cycle to achieve high electric efficiency, comparable to GTCC plants with up to 60%el. A design study was conducted to investigate the potential of pressurized chemical looping combustion of natural gas for power generation, as well as its limitations. Basic design calculations have been carried out based on fluidization engineering methods and a practical process configuration has been evaluated based on mass- and energy balances. It turns out that a high gas turbine single cycle efficiency (>14%el) can only be reached if the CLC air reactor is operated at high temperature levels (>1000°C). An optimal range of operating conditions was identified for operation of a pressurized CLC plant and design considerations for a Dual Circulating Fluidized Bed reactor system are reported. Accordingly, also the fluidization gas (steam) demand for loop seals turns out to be relatively increased for pressurized systems. Based on the results of the present work, a net efficiency of up to 40.34%el can be expected for power generation from pressurized CLC, which is low compared to standard GTCC technology with and without CO2 capture measures implemented. The reasons are the limitation of reactor/turbine inlet temperature, higher relative pressure drop of CLC systems compared to conventional turbine combustion chambers, and the required loop seal fluidization steam.

Recent development and application of a new safety analysis code for fusion reactors

This paper describes the recent progress made in the development of two codes for fusion reactor safety assessments at the Idaho National Laboratory (INL): MELCOR for fusion and the Tritium Migration Analysis Program (TMAP). During the ITER engineering design activity (EDA), the INL Fusion Safety Program (FSP) modified the MELCOR 1.8.2 code for fusion applications to perform ITER thermal hydraulic safety analyses. Because MELCOR has undergone many improvements at SNL-NM since version 1.8.2 was released, the INL FSP recently imported these same fusion modifications into the MELCOR 1.8.6 code, along with the multiple fluids modifications of MELCOR 1.8.5 for fusion used in US advanced fusion reactor design studies. TMAP has also been under development for several decades at the INL by the FSP. TMAP treats multi-specie surface absorption and diffusion in composite materials with dislocation traps, plus the movement of these species from room to room by fluid flow within a given facility. Recently, TMAP was updated to consider multiple trap site types to allow the simulation of experimental data from neutron irradiated tungsten. The natural development path for both of these codes is to merge their capabilities into one computer code to provide a more comprehensive safety tool for analyzing accidents in fusion reactors. In this paper we detail recent developments in this area and the application of this new capability to a DEMO relevant water-cooled tungsten armored divertor.

Model-assisted analysis of fluidized bed chemical-looping reactors

A three-phase hydrodynamic model is employed for the analysis of experimental data of chemical-looping reduction with nickel-based oxygen carriers and methane as the fuel. The model rigorously accounts for the mass, energy, and pressure balances, and the effect of oxygen carrier entrainment in the freeboard region. Model predictions are in good agreement with the relevant experimental data. The capability of the model to be used in the scale-up of fixed-bed kinetic studies of oxygen carriers to fluidized bed pilot-scale reactors is illustrated. The generality and validity of the model are analyzed, so that it can be used for further reactor design studies. In particular, sensitivity analyses, in terms of the crucial hydrodynamic parameters and correlations are carried out and the effects of important parameters, such as bubble size, mass transfer, oxygen carrier entrainment and reactions in the freeboard, on the performance of the chemical-looping reducer are investigated.

A Study of Fuel and Reactor Design for Platinum Nanoparticle Catalyzed Microreactors

Typical microcombustion‐based power devices entail the use of catalyst to sustain combustion in less than millimeter scale channels. This work explores the use of several other candidate fuels for ~8 nm diameter Pt particle catalyzed combustion within 800 μm channel width cordierite substrates. The results demonstrate while commercial hydrocarbon fuels such as methane, propane, butane, and ethanol can be used to sustain catalytic combustion, room temperature ignition was only observed using methanol‐air mixtures. Fuels, other than methanol, required preheating at temperatures >200°C, yet repeated catalytic cycling similar to methanol‐air mixtures was demonstrated. Subsequently, a new reactor design was investigated to couple with thermoelectric generators. The modified reactor design enabled ignition of methanol‐air mixtures at room temperature with the ability to achieve repeat catalytic cycles. Preliminary performance studies achieved a maximum temperature difference ΔT of 55°C with a flow rate of 800 mL/min. While the temperature difference indicates a respectable potential for power generation, reduced exhaust temperature and improved thermal management could significantly enhance the eventual device performance.

Bootstrap current fraction scaling for a tokamak reactor design study

We have derived new bootstrap current fraction scalings for systems codes by solving the Hirshman–Sigmar model, which is valid for arbitrary aspect ratios and collision conditions. The bootstrap current density calculation module in the ACCOME code was used with the matrix inversion method without the large aspect ratio assumption. Nine self-consistent MHD equilibria, which cover conventional, advanced and spherical tokamaks with normal or reversed shear, were constructed using numerical calculations in order to compare the bootstrap current fraction values with those of the new model and all six existing models. The Wilson formula successfully predicted the bootstrap current fraction, but it requires current density profile index for the calculation. The new scaling formulas and IPDG accurately estimated the bootstrap current fraction for the normal and weakly reversed shear tokamaks, regardless of the aspect ratio. However, none of the existing models except the Wilson formula can accurately estimate the bootstrap current fraction for the reversed shear tokamaks, which is promising for the advanced tokamak operation mode.

Study of a Small-Scale Controllable Reactor and Conceptual Design of a 35kV/5Mvar HTS Reactor

Since Ultra High Voltage (UHV) transmission lines have the high charging capacitance, continuous reactive power compensation is vital for efficient operation of long transmission power lines or cables. A continuous reactive compensation will reduce the transmission losses and increase the transmission capacity of active power. In order to achieve the continuous reactive power compensation, we choose the magnetic saturable type reactor. The principle of a magnetic saturable reactor requires a high current ampere-turn coil as its dc bias, and this coil is necessary to use a high temperature superconducting (HTS) winding. As the first stage of the study, we have constructed a 220V small-scale prototype which the dc bias is made of copper coil instead of the HTS coil. The copper coil of the dc bias in small-scale reactor has the same ampere-turn with a 220V HTS controllable reactor (HCR), so its performance keeps the same except the HTS part. Based on this, we made a conceptual design for a 35kV/5Mvar HCR. The output property and harmonic property have been studied by simulation and experiment. The results prove that it can obtain a continuous controllable reactive power output.

Measurement of the 54,57Fe(n,γ) Cross Section in the Resolved Resonance Region at CERN n_TOF

54Fe and 57Fe are stable iron isotopes, which play an important role in the nucleosynthesis of the slow neutron capture process (s process). In addition, these nuclei are present in many structural materials, and therefore, the knowledge of their neutron capture cross sections is of importance for reactor design studies. This contribution summarizes the results of the (n, γ) cross sections of these two isotopes in the resolved resonance region. The experiment was carried out at the CERN n_TOF facility using the Pulse-Height Weighting Technique in combination with an experimental set-up optmized for reducing neutron induced backgrounds.