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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

氦氙气冷移动式反应堆堆芯物理计算分析

移动式反应堆固有安全性高、经济性好、部署灵活,是未来先进反应堆技术发展的重要方向。高温气冷堆因其性能特点在移动式反应堆设计中广受青睐,基于此提出一种使用氦氙为冷却剂、低浓度TRISO包覆颗粒为燃料的移动式反应堆堆芯方案,并使用蒙特卡罗程序MCNP对其进行物理特性研究计算。计算结果表明:本文方案为超热堆,功率分布合理,控制系统价值足够;温度功率效应为负值,满足设计要求;后备反应性充足,可支持满功率运行1500 EFPD;本文方案相比其他先进移动式反应堆体积较小,但燃耗深度相对较浅。总体而言本文提出的堆芯方案合理,能够满足设计要求。

生产乙烯基硅油反应釜的改进设计

通过改进设计提升生产乙烯基硅油反应釜的性能和效率。首先,我们分析了乙烯基硅油反应釜目前存在的问题及其在化工工业中的重要性。然后,我们明确了本研究的目的,即通过改进设计来解决现有反应釜的问题,并提高乙烯基硅油的生产效率。针对此目标,我们采用了一系列适当的研究方法和途径来设计和优化反应釜的结构和工艺。经过实验和测试,我们得出了精确和可靠的结果,并发现改进后的反应釜在乙烯基硅油生产过程中表现出优异的性能。最后,根据研究结果,本文总结了改进设计的优点和意义,对于提升乙烯基硅油生产工艺和化工工业具有重要意义。

燃煤电厂新型SCR反应器结构设计

燃煤电厂目前普遍采用选择性催化还原(SCR)法进行烟气脱硝,SCR反应器是烟气脱硝处理的主要设备,其设计方案直接影响烟气脱硝性能.SCR反应器在运行时承受多种荷载和作用,常规设计通常采用保守的框架形式,其材料利用率和受力性能存在局限性.为实现SCR反应器结构的高性能设计,对其受力特点和结构方案进行了研究,形成了结构空间布置和截面优化、提高结构刚度、温度应力和膨胀变形控制、内部压力控制、防积灰措施等关键技术解决方案,设计了一种新型SCR反应器结构.结果表明:该新型SCR反应器结构布置合理,催化剂层大梁的高度可以降低约50%,总用钢量可以节省约20%,同时有限元仿真分析表明结构具有良好的受力性能和安全性能.该新型SCR反应器在多个项目中得到了应用,使电厂氮氧化物(NO_(x))排放得到了有效控制,产生了显著的效益.

基于ACE Reactor的BSC功能测试系统设计

GSM通信工程迫切需要对BSC系统进行各种功能测试,而软硬件环境的多样性和异构性,使得BSC平台架构上的测试相当困难。为了减少整个通信软件的成本,简化各种配置的复杂性,利用ACE中间件丰富的组件和Reactor框架设计模式,使用软件仿真硬件所实现的逻辑。通过引入两个插桩,来仿真两个物理的NetHawkServer卡,在LinuxOS下建立了基于IP通信的功能测试环境。实验证明了新测试系统的可靠性和健壮性,并解决了昂贵测试硬件短缺的问题。

多线程环境下Reactor模式的研究与实现

介绍了三种多线程环境下的Reactor模式的实现,分别是:开源网络库NMSTL、开源网络库Muduo以及作者基于Reactor模式实现的网络库。本文讨论了实现Reactor模式时,需要完成的定时器,为实现TCP通信需要实现的非阻塞连接器、接受器、读写操作等,对类对象生命周期的管理以及在多线程环境下使用时还需要进行的同步设计。

EXPERIMENTAL INVESTIGATION OF KINETIC AND TRANSPORT PARAMETERS IN A WALL－COOLED FIXED－BED REACTOR

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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.

泳池式低温供热堆用衰减筒的设计

衰减筒是池式低温供热堆的主要部件,其功能是保证堆芯出口的放射性冷却水在衰减筒内的滞留时间不低于100s,使短周期放射性核素在池内大量衰减,从而使一回路的放射性水平显著降低。根据整体布置要求,该衰减筒的筒体结构为不规则扇形结构,并在内部设置有分流板和孔板。其设计工作主要包括结构设计、冷却水衰减时间计算以及结构件的强度分析计算,并通过相关计算结果对设计进行优化。最终的设计结果表明,衰减筒的结构设计满足功能要求,冷却水在衰减筒内的衰减时间不低于100s,且强度分析计算满足设计要求。

船用金属氢化物储氢技术研究综述

金属氢化物储氢是一种基于化学吸收原理的氢气储存方法,具有高体积储氢密度和高安全性的特点,在船舶储氢领域的应用潜力备受关注。在此背景下,对于金属氢化物储氢技术在船舶上的应用,有着材料性能、反应器性能、热管理系统、成本等一系列有待研究的问题。首先,对金属氢化物储氢技术进行归纳,总结梳理金属氢化物的工作原理及材料性能方面的研究进展,并介绍金属氢化物在船舶上的应用情况;然后,结合氢能船舶的应用环境及需求,分析金属氢化物储氢技术在船舶上应用的技术、经济可行性,并以满足氢能船舶对氢气储量和放氢速率要求为目标,介绍船用金属氢化物储氢系统的研究,包括储氢系统性能研究、储氢反应器结构、反应器结构优化、耦合船舶燃料电池的热管理系统和储氢系统设计思路;最后,结合上述研究内容,对船用金属氢化物储氢系统的研究方向进行总结与展望。

“玲龙一号”小堆堆芯与安全设计

“玲龙一号”(ACP100)作为一款多用途小型模块化反应堆,是我国核电技术自主研发的标志性成果。“玲龙一号”在研发过程、堆芯和安全设计中的关键技术,主要涵盖堆芯核设计、热工水力设计、安全设计理念、固有安全设计、事故应对策略等,通过引入“全非能动”的安全设计理念,同时融合确定论与概率论的分析方法,大幅提升了“玲龙一号”的安全性,全面满足并超越了三代核电安全标准。