Strategies for high-performance supercapacitors for HEV

Our paper highlights the role of supercapacitors in hybrid electric vehicles (HEVs), the current response to the worldwide demand for a clean and low fuel-consuming transport. The main strategies for increasing the specific energy of supercapacitors, which are electrochemical energy storage/conversion systems of high-specific power, are discussed, with the focus on electrode material, electrolyte and electrode/electrolyte interface properties. Particular emphasis is given to the use of ionic liquids (IL), which are attracting much attention as green and solvent-free electrolytes, and to the development of high-voltage, IL-based hybrid supercapacitor with high surface area carbon negative electrode and poly(3-methylthiophene) positive. Based on the results of laboratory cells featuring N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide and 1-ethyl-3-methyl-imidazolium bis(trifluoromethanesulfonylimide) ILs, the specific energies of hybrid supercapacitor modules are evaluated and compared to those expected for double-layer carbon supercapacitors displaying the same ILs.     

面向2050年的中国电力发展展望

电力转型是我国能源转型的重要环节。本文基于自主开发的适合我国中长期电力发展的源网荷储协调规划模型,将各类电源、骨干电网、需求侧资源与储能等统筹考虑,在计及相关发展目标与约束条件的情况下进行系统整体优化,求解了我国当前至2050年电力系统发展优化方案,可为研判我国电力系统发展路径、制定合理转型政策提供量化参考。     

Rules for paths construction for HENs debottlenecking

This paper is based on the heat exchanger network retrofit techniques, developed by Tjoe and Linnhoff and extended by Asante and Zhu. It considers, under the Network Pinch framework, two important cases — the Retrofit Initialisation and Topology Modification when the direct application of the classic Network Pinch concept and rules is not possible. With the help of a system of simple heuristics, these limitations are overcome which extends the application range of the Network Pinch framework.     

固定床反应器催化剂装填方案的优化

脱砷反应器压降升高会严重影响压缩机的安全运行,同时也制约了装置的加工量。分析认为,压降升高的主要原因是床层空隙率减小,而空隙率减小的主要原因是床层杂质增多,堵塞了颗粒间的空隙。阐述了级配剂和除垢篮在抑制压降升高方面的作用,提出级配剂加除垢篮的组合装填方案,有效解决了固定床反应器的压降问题,使撇头周期达到9个月,并对装填方案的进一步优化提出建议。     

Energy use for subsistence and prospects for development

This paper focuses on the present use of energy in the developing countries in order to estimate the energy required for subsistence-level activities and to see how much surplus is available for economically productive activities, taking into account both commercial and non-commercial (firewood, farmwaste) sources of energy. The energy required for subsistence is estimated to be in the range of 0.3 to 0.4 tce per capita. The consumption of most low income groups countries is below this level if only commercial energy is considered. Relations are derived to explain the uses of each of these energy forms in terms of economic and demographic variables from a sample of 82 countries. These relations are then employed to show that the dependence on non-commercial energy is likely to continue beyond 2000 AD and that, inspite of the annual rise of commercial energy consumption by 6%, the improvements in per capita consumption are small because of an increase in population and a decrease in per capita non-commercial energy.     

汽轮机低压叶片材料的选择

汽轮机低压叶片的材料选择对于保证整个汽轮发电机组的安全运行至关重要。从几个方面分析讨论了汽轮机低压叶片材料选择时需要注意的问题，并提出了解决办法。     

汽轮机转子临界转速计算方法

汽轮机转子临界转速分析计算是汽轮机结构设计应用中最关键的一个环节,对汽轮机转子的安全运行和全寿命管理具有非常重要的意义。分别采取能量法和分析法的方式来计算转子的临界转速,并对两种计算方法进行了相应的对比,在实际工程中具有很高的实用价值。     

Methodology for repair/replacement decisions for flawed components

After an introduction to the Japanese organization for safety regulations administration for commercial nuclear power plants, a review is made of historical changes in capacity factor, share percentage of electricity generated by nuclear power plants, and annual incidence of accident, trouble and deficiency. Next, the administrative organization for repair and replacement decisions for flawed structural components in plant is described. Finally the paper discusses two examples of research work carried out for the elucidation of the cause and mechanism of structural failures of splitter plates in PWRs and of bearing rings of hydrostatic bearing in a BWR.     

Test Procedures for Heat Storages for Solar Heating Systems

The Danish Government supports producers of systems for renewable energy sources (solar, wind, biomass). At present the consumer will receive 30% of the investments in the installed solar heating system. In order to participate in this arrangement it is required of the producers that the components of their solar heating systems are tested. The heat storages are tested at the Thermal Insulation Laboratory at the Technical University of Denmark. Tests of marketed heat storages for solar heating systems for domestic hot water supply started in 1979, and since then the test procedures have been changed continuously according to the experience gained. The test procedure in use now and some of the experiences gained will be described in the following.     

Quantitative evaluation for effective removal of phosphorus for SoG-Si

Production of solar cells has increased rapidly in recent years, and metallurgical production of solar grade silicon (SoG-Si), has increased compared with more expensive processes such as Siemens process and Cz processes. It is important to understand the thermodynamic behavior of phosphorus in slag for optimized refinement of SoG-Si. In this study, the thermodynamic behavior of phosphorus in the CaO-SiO₂-CaF₂ slag system was investigated at 1773 K for various oxygen potential and slag composition. In addition, evaporation of phosphorus in the reduction process was observed during slag refining by addition of H₂ gas.Experimental results showed that the stability of phosphorus in slag depends on both the O²⁻(basicity) content of the slag and the solubility of Ca in silicon, and the dissolution mechanism of phosphorus into slag was derived. Results confirmed that phosphorus and calcium in molten silicon were also removed by acid leaching. The effective removal of phosphorus for SoG-Si using several refining processes was evaluated quantitatively.     

Barriers and opportunities for labels for highly energy-efficient houses

Promoting energy efficiency in the building sector is essential if the agreements of the Kyoto Protocol are to be honoured. Different initiatives for energy labelling of highly energy-efficient residential buildings have emerged throughout Europe as an essential method to stimulate market demand, to control grants or to ensure the quality of demonstration projects with excellent energy performance.     

Strategy for selection of elements for heat transfer enhancement

The present paper points out that the selection of elements for heat transfer enhancement in heat exchangers requires a methodology to make a direct comparison of the performances of heat exchanger surfaces with different elements. Methods of comparison used in the past are, in many respects, approximate and hence fail to predict accurately the relative performance of conventional heat exchanger surfaces operated with different heat exchanger elements. Owing to the direct use of the Colburn factor for performance assessment, these methods over-predict the relative performance of heat exchangers. In the present paper, a more consistent comparison method is presented and is demonstrated to work by comparison of the performance of an experimentally investigated pin fin heat exchanger with that of a smooth pipe heat exchanger. The method yields results that belong to the volume goodness factors group. It represents a practical approach, as it is applicable to all kinds of heat exchanger surfaces and does not require the conversion of the experimental data in terms of Nusselt number and friction factor for comparison purposes. The present work demonstrates that the suggested method can also be used for performance comparison of existing heat exchanger surfaces with available heat transfer and pressure loss data.     

Prospects for secure and sustainable electricity supply for Pakistan

Fossil fuel reserves are diminishing rapidly across the world, intensifying the stress on existing reserves day-by-day due to increased demand. Not only that, fossil fuels, presently contributing to 80% of world primary energy, are inflicting enormous impacts on environment. Energy sector has a key role in this regard since energy during its production, distribution and consumption is responsible for producing environmentally harmful substances. There is an urgent need for a quicker switch over of energy systems from conventional to renewables that are sustainable and can meet the present and projected world energy demand. Hydrogen, in the capacity of energy vector and storage medium is expected to be the optimum solution for intermittency and storage of energy produced by renewables. Within the context of Pakistan solar and wind power are two of the most promising renewables.In this article, the current energy consumption for Pakistan is presented and the issue of security of electrical energy supply is discussed. Furthermore, the prospects for a large-scale switch over to renewables are also addressed and the relevant economies and underpinning rationale provided. It has been found that solar energy is a much more economical choice for Pakistan as compared to wind energy-respective costs for solar and wind energy are (US cents/kWh) 20 and 77. This is due to the fact barring the four monsoon months, the average wind speed for the remaining 8 months does not cross an economic threshold. On the contrary, it was found that solar energy has a fairly stable and consistent availability.     

Water-soluble binders for MCMB carbon anodes for lithium-ion batteries

We have investigated the suitability of four different binders for the conventional mesocarbon microbeads (MCMBs) anode material in Li-ion batteries. Unlike the conventional polyvinylidene fluoride (PVDF), the binders were water soluble and were either cellulose based, such as the lithium and sodium salts of carboxymethyl cellulose (NaCMC, and LiCMC) and Xanthan Gum (XG), or the conjugated polymer: poly(3,4-ethylendioxythiophene) (PEDOT, a.k.a. Baytron). All binders were commercially available except LiCMC, which was synthesized and characterized by FTIR and NMR. Thermal studies of the binders by TGA and DSC showed that, in air, the binders have a broad melting event at 100-150 °C, with an onset temperature for decomposition above 220 °C. Li/MCMB half-cell batteries were assembled using the studied binders. Slow scan voltammograms of all cells showed characteristic lithium insertion and de-insertion peaks including that of the SEI formation which was found to be embedded into the insertion peaks during the first cycle. Cycling of the cells showed that the one containing XG binder gave the highest capacities reaching 350 mAh g⁻¹ after 100 cycles at C/12, while the others gave comparable capacities to those of the conventional binder PVDF. The rate capabilities of cells were examined and found to perform well up to the studied C/2 rate with more than 50% capacity retained. Further studies of the XG-based MCMB electrodes were performed and concluded that an optimal thickness of 300-365 μm gave the highest capacities and sustained high C-rates.     

轧辊退火热处理炉自动控制系统

介绍了轧辊退火生产中自动控制系统的组成和各部分设备功能,通过此集散控制系统实现温度精确控制、数据记录监视以及仪表、电气设备的控制联锁。     

Probabilistic design factors for pipes used for hydrogen transport

Probabilistic design factors for pipes used for hydrogen transport are proposed for 3 locations: urban, peri-urban and rural areas.The used method involves a risk equation defined as the product of probability of leakage after failure, probability to have a gas flow greater than a prescribed value, probability of ignition, probability of lethal effects greater than a threshold value and probability of the presence of a person corrected by an environment factor and a risk reduction coefficient. The results obtained are less conservative than the deterministic values provided by ASME code.     

Economic requirements for new materials for solar photovoltaic cells

This paper describes the economic requirements which must be considered when examining the possibility of new materials for large scale solar photovoltaic applications. On the basis of these economic requirements, most of the new photovoltaic materials proposed by Schoijet[1] can be eliminated as serious candidates. Also, it is shown that highly efficient MIS solar cells can be fabricated using cheap and abundant Al and Si, thus there is no need to replace metals in Schotty devices by complex compounds.