中低温太阳能-甲醇重整互补供能系统动力学提升与系统优化

本文考察了中低温-甲醇重整互补制氢及其与高温质子交换膜燃料电池(HT-PEMFC)结合的中低温太阳能-甲醇重整互补发电系统,并分析、优化了两供能系统的性能.从动力学性能优化角度,研发了一种适用于甲醇重整制氢反应的新型复合金属氧化物纳米催化剂,并测试了不同反应物体积流量与反应温度下的催化剂性能.基于动力学实验结果,模拟了...     

小型模块化熔盐堆钍利用方案

钍基熔盐堆（Thorium Molten Salt Reactor,TMSR）核能系统先导专项的研究目标是研发第四代裂变反应堆核能系统（即钍基熔盐堆）。为充分利用液态燃料熔盐堆的在线添料与在线燃料处理的优势,同时考虑熔盐堆的快速部署,TMSR先导专项部署了小型模块化熔盐堆。考虑燃料处理技术现状及其可能的发展方向,小型模块化熔盐堆钍利用方案采用"三步走"战略。第一阶段采用在线加料与离线处理,实现钍的成规模利用;第二阶段采用在线加料和在线处理（U）与离线处理（MA）的结合,实现钍的高效利用;第三阶段采用在线加料及在线处理全部重金属,实现钍的自持增殖利用。随着"三步走"战略的逐步实施,钍铀燃料循环模式及后处理性能稳步提高,重金属利用率得到明显改善,同时有效降低了卸料毒性。考虑燃料许可容易度和建堆时间,首先为钍利用方案第一阶段布置了三种可能的启堆燃料,分别为低富集铀、低富集铀加钍和233U加钍。计算结果显示:以低富集铀启堆时,燃料循环性能与水堆相当;以233U启堆时,燃料利用率明显高于水堆,且其放射性毒性比水堆低约2个数量级。The missions of the Thorium Molten Salt Reactor (TMSR) Nuclear Energy System are to research and develop the thorium based molten salt reactors (MSR) belonging to the fourth generation of nuclear fission reactor system. A Small modular Molten Salt Reactor (SmMSR) is deployed to make full use of the advantages of online refueling and online reprocessing and to consider the rapid deployment of MSR. An innovative "three-stage" strategy of thorium utilization based on SmMSR is proposed to take the current condition of fuel reprocessing and its future evolution. The first stage can realize the thorium utilization at a large scale with online refueling and off-line processing. The second stage can obtain efficient thorium utilization with online refueling, online processing of uranium and off-line processing of minor actinides (MAs). The third stage is implemented with self-sustaining or breeding mode with online refueling and online processing of all heavy metals. Along with the development of three stages, the utilization of heavy metals will be obviously improved and the radio-toxicity will be significantly reduced. A SmMSR is designed to achieve the goals of the first stage of thorium utilization. And three kinds of nuclear fuel cycles with different startup fuel types (i.e., low enriched uranium (LEU), thorium mixed with LEU (LEU+Th) and thorium mixed with 233U (233U+Th)) are implemented. The results show that the performance for fuel cycle containing LEU is comparable to the pressurized-water reactor (PWR). Meanwhile, the nuclear utilization for that containing 233U is much higher than PWR, and the radio-toxicity for which is lower by ~2 magnitudes than that for PWR.     

Accelerator-driven sub-critical reactor system (ADS) for nuclear energy generation

In this talk we present an overview of accelerator-driven sub-critical reactor systems (ADS), and bring out their attractive features for the elimination of troublesome long-lived components of the spent fuel, as well as for nuclear energy generation utilizing thorium as fuel. In India, there is an interest in the programmes of development of high-energy and high-current accelerators due to the potential of ADS in utilizing the vast resources of thorium in the country for nuclear power generation. The accelerator related activities planned in this direction will be outlined.     

基于化学链燃烧的氢氧联合循环

提出一种新颖的基于化学链的氢氧联合动力循环系统,该系统利用透平余热提供化学链中天然气和Fe3O4反应热,将余热转换为高品位化学能。系统综合了化学链零能耗分离CO2和氢氧联合循环高效率的优点。与化学链燃烧联合循环相比,该循环取消了余热锅炉和底循环,系统内能量品位匹配更加合理。根据图像分析方法,阐明了化学链氢氧联合循环中损...     

New alkali doped pillared carbon materials designed to achieve practical reversible hydrogen storage for transportation

We propose a new generation of materials to maximize reversible H2 storage at room temperature and modest pressures (<20 bars). We test these materials using grand canonical Monte Carlo simulations with a first-principles-derived force field and find that the Li pillared graphene sheet system can take up 6.5 mass% of H2 (a density of 62.9 kg/m(3) at 20 bars and room temperature. This satisfies the DOE (Department of Energy) target of hydrogen-storage materials for transportation. We also suggest ways to synthesize these systems. In addition we show that Li-doped pillared single-wall nanotubes can lead to a hydrogen-storage capacity of 6.0 mass% and 61.7 kg/m(3) at 50 bars and room temperature storage, which is close to the DOE target.     

MRI Application for Clarifying Fuel Cell Performance with Variation of Polymer Electrolyte Membranes: Comparison of Water Content of a Hydrocarbon Membrane and a Perfluorinated Membrane

Magnetic resonance imaging (MRI) is applied to clarify a dominating factor on variation of fuel cell performance with two types of polymer electrolyte membranes, a hydrocarbon membrane and a perfluorinated membrane. MRI results revealed that the hydrocarbon membrane showed a water content higher than that of the perfluorinated membrane, responsible for a better fuel cell performance due to decrease of resistance loss of the fuel cell. Authors' address: Shohji Tsushima, Research Center for Carbon Recycling and Energy, Tokyo Institute of Technology, 2-12-1, Ohokayama, Meguro-ku, Tokyo 152-8552, Japan     

燃料电池概述

燃料电池在固定与分散电站、交通运输、移动电源等方面广阔的应用前景现已受到许多研究单位和公司的广泛关注，文章简要介绍了几种主要类型燃料电池(碱性燃料电池alkaline fuel cell，AFC)、磷酸燃料电池(phosphoric acid fuel cell，PAFC)、熔融碳酸盐燃料电池(molten carbonate fuel cell，MCFC)、固体氧化物燃料电池(solid oxide fuel cell，SOFC)、质子交换膜燃料电池(proton exchange membrane fuel cell，PEMFC)、直接醇类燃料电池(direct alcohol fuel cell，DAFC)的特点、研究状况、市场需求和技术挑战，初步探讨了我国燃料电池研究开发的前景。     

Spatio-temporal evolution of cavity ignition in supersonic flow

Successful ignition in the recirculating flow of a scramjet flame holder can be highly dependent upon the location of energy deposition because of the spatial variation of fuel concentration and flow properties. The current work experimentally investigated ignition processes when energy was deposited (～100 mJ) via a spark discharge at four locations in the base of a cavity or by laser-induced breakdown in a Mach 2 flow with a stagnation temperature and pressure of 590 K and 483 kPa, respectively. The cavity was directly fueled with ethylene injection. The time dependent heat release was imaged at 40,000 frames per second and fuel concentration and distribution measurements were taken in the cavity prior to ignition. The average fuel concentration at the lean and rich ignition limits near the energy deposition locations measured 4.4–9.3% (Φ= 0.75 to 1.47). Energy deposition near the cavity step resulted in near immediate ignition kernel development and rapid achievement of self-sustained flame propagation in the front of the cavity, often faster than the bulk recirculation time of the cavity, leading to a spike in heat release. Energy deposition away from the cavity step region led to competition between local flow velocity, fuel concentration, and flame propagation rates. Ignition kernels formed along the floor of the cavity towards the closeout ramp and were rapidly advected towards the cavity step region before flame propagation could ensue. The fastest and most robust ignition events for all fueling cases showed rapid spanwise flame propagation near the cavity step.     

Fuel cycle for a fusion neutron source

The concept of a tokamak-based stationary fusion neutron source (FNS) for scientific research (neutron diffraction, etc.), tests of structural materials for future fusion reactors, nuclear waste transmutation, fission reactor fuel production, and control of subcritical nuclear systems (fusion–fission hybrid reactor) is being developed in Russia. The fuel cycle system is one of the most important systems of FNS that provides circulation and reprocessing of the deuterium–tritium fuel mixture in all fusion reactor systems: the vacuum chamber, neutral injection system, cryogenic pumps, tritium purification system, separation system, storage system, and tritium-breeding blanket. The existing technologies need to be significantly upgraded since the engineering solutions adopted in the ITER project can be only partially used in the FNS (considering the capacity factor higher than 0.3, tritium flow up to 200 m³Pa/s, and temperature of reactor elements up to 650°C). The deuterium–tritium fuel cycle of the stationary FNS is considered. The TC-FNS computer code developed for estimating the tritium distribution in the systems of FNS is described. The code calculates tritium flows and inventory in tokamak systems (vacuum chamber, cryogenic pumps, neutral injection system, fuel mixture purification system, isotope separation system, tritium storage system) and takes into account tritium loss in the fuel cycle due to thermonuclear burnup and β decay. For the two facility versions considered, FNS-ST and DEMO-FNS, the amount of fuel mixture needed for uninterrupted operation of all fuel cycle systems is 0.9 and 1.4 kg, consequently, and the tritium consumption is 0.3 and 1.8 kg per year, including 35 and 55 g/yr, respectively, due to tritium decay.     

冷热电联产系统的评价准则

本文通过对以燃气轮机回热循环为动力系统的冷热电联产系统进行热力学分析,对几种常用的评价准则进行了比较。通过分析,认为能量利用系数将冷、热、电等各股能量等价看待,(火用)效率过分看重能量的作功能力,折合发电效率过分关注冷、热能的输出,均不适于冷热电联产系统的评价;节能率反映的是输入能量的使用情况,经济(火用)效率在某种程度上是经济性的表现,比较适于冷热电联产系统的评价。研究中发现,燃气轮机温比有利于系统性能的提高,但针对不同的目标有不同的最佳压比;在节能率的使用中需要明确参照系统的性能。     

The 2006-2008 oil bubble: Evidence of speculation, and prediction

We present an analysis of oil prices in USD and in other major currencies that diagnoses unsustainable faster-than-exponential behavior. This supports the hypothesis that the recent oil price run-up was amplified by speculative behavior of the type found during a bubble-like expansion. We also attempt to unravel the information hidden in the oil supply-demand data reported by two leading agencies, the US Energy Information Administration (EIA) and the International Energy Agency (IEA). We suggest that the found increasing discrepancy between the EIA and IEA figures provides a measure of the estimation errors. Rather than a clear transition to a supply restricted regime, we interpret the discrepancy between the IEA and EIA as a signature of uncertainty, and there is no better fuel than uncertainty to promote speculation! Our post-crash analysis confirms that the oil peak in July 2008 occurred within the expected 80% confidence interval predicted with data available in our pre-crash analysis.     

二甲醚分产及二甲醚-动力联产的比较

本文针对DME分产及其与动力结合后的联产系统进行了研究。分产时一步法DME的能耗为55．5 GJ／t,比两步法的能耗58．0 GJ／t降低4．3％。与IGCC结合后的一步法联产相对节能率达到16．6%,远远高于两步法联产的4．9％。进一步分析发现,不论是一步法还是两步法,相对分产而言,联产时在化学(?)和物理(?)的梯级利用上都更合理。研究还表明一步法联产中对合成气化学(?)品位的充分利用是导致一步法联产节能率高于两步法联产的根本原因。     

Accelerator development in India for ADS programme

At BARC, development of a Low Energy High Intensity Proton Accelerator (LEHIPA), as front-end injector of the 1 GeV accelerator for the ADS programme, has been initiated. The major components of LEHIPA (20 MeV, 30 mA) are a 50 keV ECR ion source, a 3 MeV Radio Frequency Quadrupole (RFQ) and a 20 meV drift tube linac (DTL). The Low Energy Beam Transport (LEBT) and Medium Energy Beam Transport (MEBT) lines match the beam from the ion source to RFQ and from RFQ to DTL respectively. Design of these systems has been completed and fabrication of their prototypes has started. Physics studies of the 20–1000 MeV part of the Linac are also in progress. In this paper, the present status of this project is presented.      

新一代航空发动机燃烧室

针对新一代高油气比(0.051及以上)航空发动机燃烧室,本文提出头部采用化学恰当比直接混合燃烧设计方案.对于新一代高压比(70及以上)低排放民用航空发动机燃烧室,由于其自着火延迟时间极短,因此采用贫油直接混合燃烧,而不能采用预混合预蒸发燃烧.本文提出了一种贫油直接混合低排放燃烧室方案,其燃油空气模由简单的压力雾化喷嘴和...     

Oxide semiconductors for solar to chemical energy conversion: nanotechnology approach

The present work considers the application of oxide semiconductors in the conversion of solar energy into the chemical energy required for water purification (removal of microbial cells and toxic organic compounds from water) and the generation of solar hydrogen fuel by photoelectrochemical water splitting. The first part of this work considers the concept of solar energy conversion by oxide semiconductors and the key performance-related properties, including electronic structure, charge transport, flat band potential and surface properties, which are responsible to the reactivity and photoreactivity of oxides with water. The performance of oxide systems for solar energy conversion is briefly considered in terms of an electronic factor. The progress of research in the formation of systems with high performance is considered in terms of specific aspects of nanotechnology, leading to the formation of systems with high performance. The nanotechnology approach in the development of high-performance photocatalysts is considered in terms of the effect of surface energy associated with the formation of nanostructured system on the formation of surface structures that exhibit outstanding properties. The unresolved problems that should be tackled in better understanding of the effect of nanostructures on properties and performance of oxide semiconductors in solar energy conversion are discussed. This part is summarised by a list of unresolved problems of crucial importance in the formation of systems with enhanced performance. This work also formulates the questions that must be addressed in order to overcome the hurdles in the formation of oxide semiconductors with high performance in water purification and the generation of solar fuel. The research strategy in the development of oxide systems with high performance, including photocatalysts for solar water purification and photoelectrodes for photoelectrochemical water splitting, is considered. The considerations are focused on the systems based on titanium dioxide of different defect disorder as well as its solid solutions and composites.     

Gain of a compressed DT fuel statistically ignited by a multispark assembly

Most of the current inertial confinement fusion (ICF) schemes are based on the ignition of a high-density DT fuel by a single, high-temperature spherical hot spot (the spark). The spark is self-generated by the implosion process, which is used to bring the fuel to high density. To start ignition the spark has to be dimensioned in such a way that the ion temperature would be greater than 5–7 keV, and that the spark radius would be greater than the α-particle range. A spark with these features is indicated as supercritical. In the scheme based on self-generated spark, ignition can fail to occur when the produced spark strongly deviates from spherical shape, which can make all the surface losses highly relevant. High deformation, or even spark splitting, can occur due to the amplification of initial deviations from spherical shape by hydrodynamic instabilities (or by secular growth) during the implosion process. In principle, ignition can be recovered if the implosion is designed in such a way as to make supercritical at least one of the portions of hot fuel which are produced in this way near stagnation. As a general trend, more compressed final assemblies are required. In this paper we present fuel gain calculations (Gain = Thermonuclear energy/Energy in the compressed fuel) for DT assemblies ignited at the end of an implosion process by a supercritical spark statistically created within a cluster of many subcritical sparks. It is assigned the total number of sparks and the probability of having at least one of them supercritical. As a function of these quantities we calculate, in the framework of an isobaric model, the average thermal energy associated with the spark assembly. The same model is also used to evaluate, by statistical arguments, the areal mass, the burn fraction, and the system’s total fuel gain. It is found that the energy distribution function of the sparks is influenced only by a single global parameter, in which the assigned ignition probability and the number of sparks are also represented. Compared to the single central-spark approach, being the final states with allowed inner turbulence, the multispark scheme is characterized by relaxed initial symmetry requirements. For multispark systems we can realistically consider the achievement of fuel gains comparable or greater than those typical of the single-spark approach, when evaluated for currently accepted spark convergence ratios. With regard to the single spark case, higher cold fuel densities are needed, as expected (typically 2×–3×, for the same gain, depending on the energy distribution function). Zh. éksp. Teor. Fiz. 113, 805–815 (March 1998) Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor.     

In situ observation of water distribution and behaviour in a polymer electrolyte fuel cell by synchrotron X‐ray imaging

In situ visualization of the distribution and behaviour of water in a polymer electrolyte fuel cell during power generation has been demonstrated using a synchrotron X‐ray imaging technique. Images were recorded using a CCD detector combined with a scintillator (Gd₂O₂S:Tb) and relay lens system, which were placed at 2.0 m or 2.5 m from the fuel cell. The images were measured continuously before and during power generation, and data on cell performance was recorded. The change of water distribution during power generation was obtained from X‐ray images normalized with the initial state of the fuel cell. Compared with other techniques for visualizing the water in fuel cells, this technique enables the water distribution and behaviour in the fuel cell to be visualized during power generation with high spatial resolution. In particular, the effects of the specifications of the gas diffusion layer on the cathode side of the fuel cell on the distribution of water were efficiently identified. This is a very powerful technique for investigating the mechanism of water flow within the fuel cell and the relationship between water behaviour and cell performance.     

Demonstration of high efficiency third harmonic conversion of high power Nd-glass laser radiation

We report on efficient conversion from 1.054 μm to 0.35 μm by third harmonic generation in two Type II KDP crystals. Energy conversion efficiencies of up to 80% have been measured under conditions applicable to large glass laser systems. A new tripling scheme used for these experiments requires a minimum of optical components and is insensitive to exact crystal alignment and laser beam divergence. A convenient scaling law allows tripling optimization for many different laser conditions.     

The Use of Hydrogen as a Fuel for Engines in the Energy Cycle of Remote Production Facilities

The approach to using hydrogen as fuel, which ensures the smooth operation of autonomous power systems that use renewable energy sources (wind or solar power installations) with the stochastic mode of power generation, has been presented. The fundamental possibility of implementing the nondetonation combustion of hydrogen via the addition of ecologically clean components or a small percentage of methane has been demonstrated by methods of mathematical modeling.

     

Extremum of the percolation cluster surface

The internal and external surfaces of a percolation cluster, as well as the total surface of the entire percolation system, are investigated numerically and analytically. Numerical simulation is carried out using the Monte Carlo method for problems of percolation over lattice sites and bonds on square and simple cubic lattices. Analytic expressions derived by using the probabilistic approach describe the behavior of such surfaces to a high degree of accuracy. It is shown that both the external and total surface areas of a percolation cluster, as well as the total area of the surface of the entire percolation system, have a peak for a certain (different in the general case) fraction of occupied sites (in the site problem) or bonds (in the bond problem). Two examples of technological processes (current generation in a fuel cell and self-propagating high-temperature synthesis in heterogeneous condensed systems) in which the surface of a percolation cluster plays a significant role are discussed.