An innovative approach to effective breeding blanket design for future fusion reactors

An effective breeding blanket is critical to support tritium self-sufficiency for future fusion reactors.The difficulty is to achieve tritium breeding ratio(TBR)target of 1.05 or more.This paper presents a new design approach to the blanket design process.It indicates that fusion blanket design is affected by universal functions based on iterations.Three aspects are worth more attention from fusion engineers in the future.The first factor is that the iterations on the material fractions affect not only structure scheme but also TBR variation.The second factor is the cooling condition affecting final TBR due to the change of the structure material proportion.The third factor is temperature field related to the tritium release.In particular,it is suggested that the statistical calculation of effective TBR must be under reasonable control of the blanket temperature field.This approach is novel for blanket engineering in development of a fusion reactor.

High-Con cent rat ion Electrosynthesis of Formic Acid/Formate from CO_(2):Reactor and Electrode Design Strategies

The electrochemical CO_(2)reduction reaction(CO_(2)RR),driven by renewable energy,provides a potential carbon-neutral avenue to convert CO_(2)into valuable fuels and feedstocks.Conversion of CO_(2)into formic acid/formate is considered one of the economical and feasible methods,owing to their high energy densities,and ease of distribution and storage.The separation of formic acid/formate from the reaction mixtures accounts for the majority of the overall CO_(2)RR process cost,while the increment of product concentration can lead to the reduction of separation cost,remarkably.In this paper,we give an overview of recent strategies for highly concentrated formic acid/formate products in CO_(2)RR.CO_(2)RR is a complex process with several different products,as it has different intermediates and reaction pathways.Therefore,this review focuses on recent study strategies that can enhance targeted formic acid/formate yield,such as the all-solid-state reactor design to deliver a high concentration of products during the reduction of CO_(2)in the electrolyzer.Firstly,some novel electrolyzers are introduced as an engineering strategy to improve the concentration of the formic acid/formate and reduce the cost of downstream separations.Also,the design of planar and gas diffusion electrodes(GDEs)with the potential to deliver high-concentration formic acid/formate in CO_(2)RR is summarized.Finally,the existing technological challenges are highlighted,and further research recommendations to achieve high-concentration products in CO_(2)RR.This review can provide some inspiration for future research to further improve the product concentration and economic benefits of CO_(2)RR.

Analysis and design of resistance-wire heater in MOCVD reactor

Metal organic chemical vapor deposition(MOCVD) is a key equipment in the manufacturing of semiconductor optoelectronic devices and microwave devices in industry. Heating system is a vital part of MOCVD. Specific heating device and thermal control technology are needed for each new reactor design. By using resistance-wire heating MOCVD reaction chamber model, thermal analysis and structure optimization of the reactor were developed from the vertical position and the distance between coils of the resistance-wire heater. It is indicated that, within a certain range, the average temperature of the graphite susceptor varies linearly with the vertical distance of heater to susceptor, and with the changed distances between the coils; furthermore, single resistance-wire heater should be placed loosely in the internal and tightly in the external. The modulate accuracy of the temperature field approximately equals the change of the average temperature corresponding to the change of the coil position.

The Statistical Experimental Design for Chemical Reactors Modeling

The Statistical Experimental Design techniques are the most powerful tools for the chemical reactors experimental modeling. Empirical models can be formulated for representing the chemical behavior of reactors with the minimal effort in the necessary number of experimental runs, hence, minimizing the consumption of chemicals and the consumption of time due to the reduction in the number of experimental runs and increasing the certainty of the results. Four types of nonthermal plasma reactors were assayed seeking for the highest efficiency in obtaining hydrogen and ethylene. Three different geometries for AC high voltage driven reactors, and only a single geometry for a DC high voltage pulse driven reactor were studied. According to the fundamental principles of chemical kinetics and considering an analogy among the reaction rate and the applied power to the plasma reactor, the four reactors are modeled following the classical chemical reactors design to understand if the behavior of the nonthermal plasma reactors can be regarded as the chemical reactors following the flow patterns of PFR (Plug Flow Reactor) or CSTR (Continuous Stirred Tank Reactor). Dehydrogenation is a common elimination reaction that takes place in nonthermal plasmas. Owing to this characteristic, a paraffinic heavy oil with an average molecular weight corresponding to C15 was used to study the production of light olefins and hydrogen.

Computer Aided Design and Performance Analysis of Inverse Fluidized Bed Biofilm Reactors with Special Reference to Bioplastic Synthesis

Poly Laevo Lactic Acid (PLLA), in spite of being an excellent bioplastic, has exorbitantly high market price due to the high cost of raw material (lactose, glucose, sucrose). Hence, its manufacture is being attempted starting from waste effluents such as cheese whey and molasses. Earlier studies on the same in fluidized bed and semifluidized bed biofilm reactors yielded encouraging results. The present study therefore involves design and analysis of inverse fluidized bed biofilm reactors for lactic acid synthesis. The performance features of the bioreactor have been studied both mathematically as well as experimentally. The inverse fluidized bed biofilm reactor has been found to provide more than 75% conversion of sucrose/lactose even at high capacities (high feed flow rates) exceeding 56,000 L/hr, within a reasonably low reactor volume. The fractional substrate conversion increases, though sluggishly, with increase in feed flow rate due to bed expansion and also with increase in cell mass concentration in biofilm due to enhancement in intrinsic rate of bioconversion. The inverse fluidized bed biofilm reactor of proposed design could be safely recommended for the commercial synthesis of polymer grade lactic acid from waste effluents such as cheese whey and molasses. The low operating cost of the bioreactor (due to downflow mode of operation) enhances the economy of the process. This would also help in significantly lowering the market price of the green plastic (PLLA) and shall promote its large scale manufacture and utilisation.

Neutronic design investigation of a liquid injection-based second shutdown system for a typical research reactor using MCNPX

Safety systems, built on state-of-the-art technology, are essential for achieving acceptable levels of plant safety to minimize hazards to the reactor and the general public. The second shutdown system(SSS) as an engineered safety feature and a part of the reactor protection system(RPS) is a means for rapidly shutting down a nuclear reactor, keeping it in a subcritical state and serving as a backup to the first shutdown system(FSS). In this research, one SSS with two types of optimum chamber designs is proposed that take into account the main current characteristic features of the Tehran research reactor with improvements over earlier designs. They are based on a liquid neutron absorber injection that is preferably different, diverse, and independent from the FSS based on the rod drop mechanism. The major design characteristics of this SSS with two different chambers were investigated using MCNPX 2.6.0 code. The performed calculations showed that the designed SSS is a reliable shutdown system, assuring an appropriate shutdown margin and injection time, with no significant effects on the effective delayed neutron fraction while causing minimal variations to the core structure. Further, the reasonable financial cost and the prolongation of the operation cycle are additional advantages of this design.

Feasibility neutronic design for the reactor core configurations of a 5 MWth transportable block-type HTR

Small long-life transportable high temperature gas-cooled reactors(HTRs) are interesting because they can safely provide electricity or heat in remote areas or to industrial users in developed or developing countries.This paper presents the neutronic design of the U-Battery,which is a 5 MWth block-type HTR with a fuel lifetime of 5–10 years.Assuming a reactor pressure vessel diameter of less than 3.7 m,some possible reactor core configurations of the 5 MWth U-Battery have been investigated using the TRITON module in SCALE 6.The neutronic analysis shows that Layout 12×2B,a scattering core containing 2 layers of 12 fuel blocks each with 20% enriched235U,reaches a fuel lifetime of 10 effective full power years(EFPYs).When the diameter of the reactor pressure vessel is reduced to 1.8 m,a fuel lifetime of 4 EFPYs will be achieved for the 5 MWth U-Battery with a 25-cm thick graphite side reflector.Layouts 6×3 and 6×4 with a 25-cm thick BeO side reflector achieve a fuel lifetime of 7 and 10 EFPYs,respectively.The comparison of the different core configurations shows that,keeping the number of fuel blocks in the reactor core constant,the annular and scattering core configurations have longer fuel lifetimes and lower fuel cost than the cylindrical ones.Moreover,for the 5 MWth U-Battery,reducing the fuel inventory in the reactor core by decreasing the diameter of fuel kernels and packing fraction of TRISO particles is more effective to lower the fuel cost than decreasing the 235U enrichment.

Calculation and Design of Dry-type Air-core Reactor

Based on the method of compound and additional conditions under the conditions of the equal temperature rise and the equal potential drop (P.D.) of resistance, the application of design software of dry-type air-core reactor is introduced in this thesis. The analytical methods of the inductance are also given. This approach is proved entirely feasible in theory through the simplification with Bartky transformation, and is able to quickly and accurately calculate reactor inductance. This paper presents the analytical methods of the loss of dry-type air-core reactor as well.

Study on neutronics design of ordered-pebble-bed fluoride-salt- cooled high-temperature experimental reactor

This paper presents a neutronics design of a 10 MW ordered-pebble-bed fluoride-salt-cooled high-temperature experimental reactor. Through delicate layout, a core with ordered arranged pebble bed can be formed,which can keep core stability and meet the space requirements for thermal hydraulics and neutronics measurements.Overall, objectives of the core include inherent safety and sufficient excess reactivity providing 120 effective full power days for experiments. Considering the requirements above, the reactive control system is designed to consist of 16 control rods distributed in the graphite reflector. Combining the large control rods worth about 18000–20000 pcm, molten salt drain supplementary means(-6980 to -3651 pcm) and negative temperature coefficient(-6.32 to -3.80 pcm/K) feedback of the whole core, the reactor can realize sufficient shutdown margin and safety under steady state. Besides, some main physical properties, such as reactivity control, neutron spectrum and flux, power density distribution, and reactivity coefficient,have been calculated and analyzed in this study. In addition, some special problems in molten salt coolant are also considered, including ~6Li depletion and tritium production.

Engineering design and numerical design for chemical looping combustion reactor: A review

Chemical looping combustion(CLC)has emerged as a cost-effective technology for carbon capture at the combustion source.The reactor,being central to the implementation of CLC,primarily adheres to two technological pathways:the dual fluidized bed reactor and the packed bed reactor.However,the intricate interaction between gas-solid reaction flow and heat/mass transfer processes in these reactors gives rise to diverse operational principles at both macroscopic and microscopic levels across various reactor forms and scales,making performance prediction challenging.Consequently,the rational design of CLC reactors poses a significant challenge in advancing this technology to commercial viability.This article offers an extensive review of the prevailing reactor designs in CLC,delving into reactor characteristics,pivotal aspects of the design process,methodologies,and representative studies in the field.The predominant reactor design approaches are categorized into engineering and numerical methods.The former encompasses phenomenological and similarity analysis methods,whereas the latter consists of macroscopic and computational fluid dynamics simulation methods.Each method possesses its theoretical framework,distinctive characteristics,appropriate applications,and respective advantages and limitations.In practical applications,integrating these aspects is essential.For instance,the engineering design,which is less costly but also less precise,is effective for quickly screening numerous potential design scenarios.In contrast,the numerical design,despite its higher computational demand and greater model complexity,offers improved predictive accuracy and is optimal for validating and refining engineering design solutions.

Thermo-mechanical Design Considerations for First Wall of A-SSTR2

The finite element analysis and calculation were performed for the blanket first-wall made of SiC/SiC composite material for Advanced Steady-state Tokamak Reactor 2, A-SSTR2, which at present is conceptually designed in Naka Fusion research establishment, JAERI. Comparison analysis and design window were analyzed using the finite element code ADINA 7.4. Through a 2D calculation for various geometrical configurations and sensitive material properties, a fundamental guideline for the first wall and blanket design are established with respect to maximum temperature, thermal and mechanical stress for many configurations. To satisfy hydrodynamic requirement, a4d4 (the dimension of coolant channel is 4 mm x 8 mm, and the distance between neighboring channels is 4 mm) was chosen as a design point for high thermal conductivity up to 50 W/m.K. In order to find a good solution for lower conductivity, more elaborate work should be done in the future. Nonetheless, the outline of design window for a specific structural material is very useful for the future A-SSTR2 first wall design.

Combined Heat and Power Design Considerations for the APR1400

To date, nuclear cogeneration applications have been limited, primarily to district heating in Eastern Europe and heavy water production in Canada. With the current global price for oil and energy, this technology is not economically viable for most countries. However, oil and fossil fuel prices are known to be highly volatile, and the Paris Agreement calls for a reduction in fossil fuel use. Under these circumstances, heat supplied by nuclear power may abruptly return to favor. To prepare for such a scenario, this study will investigate design considerations for a prototypical modem nuclear power plant, the Korean APR1400 （advanced power reactor 1400） （e.g., Shin Kori Units 3, 4, Shin Hanul 1, 2, Barakah Units 1, 2, 3, 4）. Nuclear cogeneration can impact balance of plant system and component design for the condensate, feedwater, extraction steam, and heater drain systems. The APR1400 turbine cycle will be reviewed for a parametric range of pressures and flow rates of the steam exported for cogeneration to identify major design challenges.

Support Operator’s Fault Diagnosis of Complex Plant Systemthrough Multilevel Flow Model and Ecological Interface Design

The paper describes a new human-interface system design method by combining the conception of Multilevel Flow Model and Ecological Interface Design to support operators’ fault diagnosis in the complex plant system. Modern man-made systems are always achieving many complex automatic and intelligent tasks so that they are becoming more and more complex and can be hardly understood by operators, who should be the primary role in system operating. This situation presents a big challenge to the operating support system that it should present the complex system in a direct and clear way to operators to and make operators understand the internal interaction of the system especially in the abnormal status to ensure the operating safety. The Multilevel Flow Model based on the idea of ”Abstraction Hierarchy”, aiming at decompressing a system by means-end and part-whole way, can be used to represent a complex system in a standard way and perform intelligent operating tasks such as fault diagnosis and process control. Ecological Interface Design, which based on the human cognitive properties, can present the internal interaction of the system in a direct way. This paper combines this two interface design conceptions to achieve two aspects, intelligent fault diagnosis and direct presentation of causal relationship of operating parameters, to support operators’ fault diagnosis in complex plant system. The design method is applied to a PWR power plant in this paper as an application example.

Electrosynthesis of H_(2)O_(2)via two-electron oxygen reduction over carbon-based catalysts:From microenvironment control to electrode/reactor design

The electrochemical production of hydrogen peroxide(H_(2)O_(2))by the two-electron oxygen reduction(2e^(-)-ORR)process has the advantages of high safety,low energy consumption,and environmental friendliness.For 2e^(-)-ORR,the catalyst/electrode is the key component as it strongly affects catalytic performance and cost.Carbon materials have the advantages of high electronic conductivity,good structural stability,easy control of nanostructures,and low cost.Therefore,it has been regarded as a promising catalyst/electrode material for the electrosynthesis of H_(2)O_(2)via 2e^(-)-ORR.In addition,studies have also considered the optimization of the liquid/gas interface by tuning the electrode surface,electrolyte pH,and reactor configurations for further improving the activity and selectivity of catalysts.In this review,we provide an in-depth discussion of the recent research on the carbon-based electrocatalysts for 2e^(-)ORR,especially in terms of microenvironment tuning,catalyst/electrode interface engineering,and reactor design for achieving stable and efficient production of H_(2)O_(2).The challenges that we are still facing and the future development prospects will then be concluded,which we believe should help the future development in this field.

Process,reactor and catalyst design:Towards application of direct conversion of methane to aromatics under nonoxidative conditions

The Mo/HZSM-5 catalyzed,non-oxidative methane dehydroaromatization reaction provides a promising direct approach for production of benzene as well as naphthalene from CH4 resources and therefore its early industrial application is highly desired.A simplified methane dehydroaromatization process that consists of only one reactor unit and two product separation units is presented,and the factors that could significantly affect the process efficiency are quantitatively analyzed.While efficiently separating and recycling up to 70vol%unreacted CH4 from the stream out of condensable aromatics separation unit might become the main problem in maximizing the process efficiency,increasing the operating temperature as high as possible of the CH4 converter in the reactor unit and raising the system operation pressure to a level somewhat higher than one atmosphere should help maximize the process performance.At process-required high reaction temperatures,however,Mo/HZSM-5 catalyst suffers from vary rapid deactivation due to serious coke formation.Therefore,it becomes necessary to employ a reactor system that enables continuous and simultaneous regeneration of deactivated catalyst so as to maintain the catalytic activity and stability of catalyst over a sufficiently long operation period.Nineteen years of sustained R&D efforts of the author’s team have led to a few applicable technologies related to preparation of a fluidizable binder-free Mo/HZSM-5 catalyst for use in fluidized bed reactors,regeneration of deactivated Mo/HZSM-5 catalyst using H_(2),and design and operation of a dual-bed circulating fluidized bed reactor system for continuous processing of the Mo/HZSM-5 catalyzed methane dehydroaromatization reaction.Operated at 1073 K and under a continuous regeneration mode,an in-house developed binder-free 6%Mo/HZSM-5 catalyst has proven to be capable of providing a stable benzene yield of approximately 13%over a cumulative period of 1800 min.Nevertheless,minimizing the catalyst deactivation by coking and developing a highly effective coke-removal and catalyst regeneration approach have still remained two important issues to be addressed in realization of early application of the Mo/HZSM-5 catalyzed methane dehydroaromatization reaction.While the key to a practical solution to these challenging issues lies in designing an advanced Mo/HZSM-5 catalyst with improved coking resistance and H_(2)-regeneration activity,effective approaches to the design of such a catalyst are presented and discussed based on four possible coke formation routes.In the end,developing a pressurized pilot-scale dual-bed type of circulating fluidized bed reactor system that is capable of providing a yearly production of benzene of approximately 35 tons and naphthalene of 5 tons is visualized to make demonstration of the industrial applicability of the Mo/HZSM-5 catalyzed methane dehydroaromatization reaction.

Design and Comparative Analysis of Small Modular Reactors for Nuclear Marine Propulsion of a Ship

The fast growth in the size and difficulty of nuclear power plant in the 1970s produced an interest in smaller, modest designs that are intrinsically safe over the usage of design features. With the development of nuclear technology, there is the need for revolution in the Maritime sector, especially the advance marine propulsion. In current years, numerous reactor manufacturers are dynamically improving small modular reactor designs with even superior use of safety features. Several designs integrate the ultimate in greater safety. They totally remove specific accident initiators from the design. Other design features benefit to reduce different types of accident or help to mitigate the accident’s consequences. Although some safety features are mutual to maximum SMR designs, irrespective of the coolant technology, other features are specific to liquid-metal cooled, water, gas, or SMR designs. Results: There have been more reactor concepts investigated in the marine propulsion area by different assemblies and research laboratories than in the power generation field, and much can be learned from their experience for land applications. The extensive use of safety features in SMRs potential to make these power plants extremely vigorous, protecting both the public and the investor. Conclusion: For these two considerations, it is recognized that a nuclear reactor is the ideal engine for naval advanced propulsion. The paper will present the work to analyze the concept design of SMRs and design a modular vessel consisting of a propulsion module.

Design and study on hydraulics characteristic of multistage anaerobic granular sludge reactor

This article provides some ideas about several key parameters in design of multistage anaerobic granular sludge reactor （MA（iSR）, and an MAGSR was designed by these ideas. By experiment this paper studies the productivity of biogas and circulation flux of wastewater. The results indicate that in certain scope the circulation flux increases in linear with the biogas productivity rise. The result by the experiment and by the hydraulics model about the circulation flux is different. The circulation flux can be several or more than ten times of the influence.

车用柴油机Urea-SCR催化器优化设计及试验研究

运用CFD手段对SCR催化器进行了优化设计,分析了初级混合管内速度分布、载体内流量均匀性等。模拟结果表明:优化设计后的SCR催化器减少了尿素液滴碰壁的几率,提高了尿素液滴与尾气的混合均匀性。对优化设计后的SCR催化器进行性能试验、初期耐久试验和道路验证试验。试验结果表明:优化设计后的SCR催化器在欧洲稳态循环(ESC)和欧洲瞬态循环(ETC)下氮氧化物(NOx)转化效率相比原结构SCR催化器分别提高了11.8%和13.8%,且能有效避免尿素结晶结石等沉积物的形成。

Precision Synthesis of a Long-Chain Silane Coupling Agent Using Micro Flow Reactors and Its Application in Dentistry

In dentistry, a wide range of materials is available for restorative treatment;a typical product of such restorative materials mainly consists of radically polymerizable monomer(s) and inorganic filler(s) (for added physical strength), as well as a surface modifier (e.g. silane coupling agent) for improved affinity between monomer and filler. It is favorable to use an optimal surface modifier depending on the respective restorative materials. However, commercially available surface modifiers, which are synthesized by the ton, are not always suited for what is required for properties of the many different dental restorative materials. As a potential solution to such a problem, we focused on the latest technology, “micro flow reactors” that enabled an on-demand low-volume synthesis of many types of surface modifiers. Using micro reaction fields of such flow reactors, we synthesized a novel long-chain silane coupling agent. Compared to the control system synthesized using a conventional reaction flask, the novel system enabled significant reduction in reaction time without inducing any major side reactions. A dental composite resin that was treated with the novel coupling agent exhibited higher toughness, suggesting that such a silane coupling agent was an effective surface modifier.

Study on Modeling Technology in Digital Reactor System

Modeling is the kernel part of a digital reactor system. As an extensible platformfor reactor conceptual design, it is very important to study modeling technology and develop somekind of tools to speed up preparation of all classical computing models. This paper introducesthe background of the project and basic conception of digital reactor. MCAM is taken as anexample for modeling and its related technologies used are given. It is an interface program forMCNP geometry model developed by FDS team (ASIPP & HUT), and designed to run on windowssystem. MCAM aims at utilizing CAD technology to facilitate creation of MCNP geometry model.There have been two ways for MCAM to utilize CAD technology: (1) Making use of user interfacetechnology in aid of generation of MCNP geometry model; (2) Making use of existing 3D CADmodel to accelerate creation of MCNP geometry model. This paper gives an overview of MCAM'smajor function. At last, several examples are given to demonstrate MCAM's various capabilities.