隔热涂层对照明炬静态发光性能的影响研究

以某照明弹照明炬为平台,就隔热涂层对其静态发光性能的影响进行试验研究,目的是在其他结构不发生改变的前提下,提高照明药剂照明效率,降低生产成本。文中通过4种隔热涂层6种试验方案的对比研究得出隔热涂层优于传统隔层的结论,利用隔热涂层热导率低、抗氧化、耐热冲击等特性,能够有效提高照明剂的照明效应,且具有长贮性好、耐潮湿、废品率低、环保等优点。该研究对加快隔热涂层在照明炬中的工程应用进程具有重要意义。

特高压直流高速开关研发关键技术研究

直流高速开关(high speed switch,HSS)是多端直流输电系统中的关键设备。HSS的性能参数直接影响到多端直流系统的送电能力和运行灵活性。为了研制性能参数更优的±800 kV HSS产品,提出在长时直流耐受、直流小电流开断和直流燃弧耐受3大关键性能方面需解决的问题。结合内外绝缘仿真优化和样机绝缘验证,实现样机具备DC1224 kV/1 h湿耐受的绝缘性能;通过小电流开断的磁流体动力学仿真,获得了HSS开断小直流电流时灭弧室内部的温度、压力分布规律;试制了小直流开断实验样机,样机实验在1 kV恢复电压下最大开断电流达到350 A。通过长时燃弧的磁流体动力学仿真,获得了4000 A直流电流开断过程中灭弧室内部的温度、压力分布规律。该研究为性能参数更优的±800 kV HSS产品研制奠定坚实基础,对提高多端直流输电系统功率连续性和安全稳定运行具有重要意义。

Model of limestone calcination / sulfation under oxy-fuel fluidized bed combustion

The characteristics of the simultaneous calcination/ sulfation of limestone under oxy-fuel fluidized bed combustion were studied and compared with those of the sulfation of precalcined CaO. During the calcination stage, SO2 can react with product CaO and slow down the CaCO3 decomposition rate by the covering effect of the CaSO4 product. The sulfation rate of simultaneous calcinatiort/sulfation is slower than that of precalcined CaO, but with a long enough sulfation time, the calcium conversion of simultaneous calcination/sulfation is higher than that of the precalcined CaO. A grain-micrograin model is established to describe the simultaneous calcination, sintering and sulfation of limestone. The graln-micrograln model can reflect the true reaction process of the calcination and sulfation of limestone in oxy-fuel fluidized bed combustion.

Characteristics of gas explosion flow fields in complex pipelines

The explosion flow field in five straight pipes with different diameters and one bending pipe selected from a domestic coal mine are studied by the method of numerical simulation. And the results show that,both in the straight and bending pipes, the pressure wave and velocity wave are accelerated by the rising of reaction rate. As the explosion progressed, with the temperature reaching approximately 3000 K, only one pressure wave and one reaction rate wave were observed, while several velocity waves were found.The larger diameter presented the highest relative pressure as well as the largest velocity increase and subsequent decrease inside the tube. The bent pipes caused both turbulence and kinetic energy to increase, resulting in the acceleration of the reaction rate. The burning time was 7.4% shorter than the burning time observed for the straight pipe. Based on these results, designing one explosion resistance device, and in the practical engineering applications, it was to be proved to meet the security requirements fully.

Coal combustion restrained by ultra-fine water mist in confined space

In order to apply ultra-fine water mist technology on spontaneous coal combustion in the goaf of a coal mine, we built a small scale compartment with ultra-fine water mist for restraining coal combustion in a confined space and then investigated the restraining efficiency and related factors. The study obtained the following results： a descending rate of heat release, an increase in 02, the production of CO2 decreased gradually, while the production of CO increased dramatically and quickly and then decreased; ultimately it tended to become stable after the discharge of an ultra-fine water mist. The technology showed that the ultra-fine water mist can effectively reduce the heat release rate of coal and the rate to generate components. We found that the restraining effect relied on the mist flux, the discharge time and other factors. A sufficient amount of mist has a better effect compared to an insufficient amount of mist. To combat coal combustion, the greater the discharge time, the better coal flames are extinguished.

多端直流用直流高速开关(HSS)关键性能考核技术研究综述

多端直流输电技术可有效缓解中国输电走廊紧缺问题,并解决大规模的清洁能源并网,通过配置直流高速开关(high-speed switch,HSS),可实现多端直流系统第三站的在线投退及直流线路故障快速隔离。但目前国内缺乏±800 kV HSS设备的制造技术与试验经验。为掌握核心技术,文中首先简要介绍多端直流输电工程对HSS的功能需求,提出HSS的运行工况及关键技术参数。其次,着重介绍研制±800 kV HSS特殊性能验证试验,包括长时燃弧耐受关键技术及无震荡回路开断直流关键技术及其研究现状,提出了±800 k V HSS关键性能的考核方法和型式试验要求,并对其下一步的研究方向给出了建议。

The shortest period of coal spontaneous combustion on the basis of oxidative heat release intensity

It’s necessary to forecast the shortest spontaneous combustion period for preventing and controlling the coal spontaneous combustion.During the experimental process,a calculating model of the SSCP is established on the basis of the oxidative heat release intensity and thermal capacity at different temperatures.According to the basic parameters of spontaneous combustion,heat of water evaporation and gas desorption,the SSCPs of different coals are further predicted.Finally,this study analyzed the relationships of the SSCP and the judging indexes of the self-ignite tendency.The result shows that the SSCP non-linearly increases with the decrease of dynamic oxygen adsorption and increase of activation energy.Compared with the practical fire situation of mine,this reliable method can meet the actual requirement of mine production.

4-D Trajectory Prediction and Dynamic Planning of Aircraft Taxiing Considering Time and Fuel

Most of the traditional taxi path planning studies assume that the aircraft is in uniform speed,and the optimization goal is the shortest taxi time.Although it is easy to solve,it does not consider the changes in the speed profile of the aircraft when turning,and the shortest taxi time does not necessarily bring the best taxi fuel consumption.In this paper,the number of turns is considered,and the improved A*algorithm is used to obtain the P static paths with the shortest sum of the straight-line distance and the turning distance of the aircraft as the feasible taxi paths.By balancing taxi time and fuel consumption,a set of Pareto optimal speed profiles are generated for each preselected path to predict the 4-D trajectory of the aircraft.Based on the 4-D trajectory prediction results,the conflict by the occupied time window in the taxiing area is detected.For the conflict aircraft,based on the priority comparison,the waiting or changing path is selected to solve the taxiing conflict.Finally,the conflict free aircraft taxiing path is generated and the area occupation time window on the path is updated.The experimental results show that the total taxi distance and turn time of the aircraft are reduced,and the fuel consumption is reduced.The proposed method has high practical application value and is expected to be applied in real-time air traffic control decision-making in the future.

Optimization of dilute acid hydrolysis of Enteromorpha

Acid hydrolysis is a simple and direct way to hydrolyze polysaccharides in biomass into fermentable sugars. To produce fermentable sugars effectively and economically for fuel ethanol, we have investigated the hydrolysis of Enteromorpha using acids that are typically used to hydrolyze biomass： H2SO4, HC1, H3PO4 and C4H404 （maleic acid）. 5%（w/w） Enteromorpha biomass was treated for different times （30, 60, and 90 min） and with different acid concentrations （0.6, 1.0, 1.4, 1.8, and 2.2%, w/w） at 121~C. H2SO4 was the most effective acid in this experiment. We then analyzed the hydrolysis process in H2SO4 in detail using high performance liquid chromatography. At a sulfuric acid concentration of 1.8% and treatment time of 60 min, the yield of ethanol fermentable sugars （glucose and xylose） was high, （230.5 mg/g dry biomass, comprising 175.2 mg/g glucose and 55.3 mg/g xylose）, with 48.6% of total reducing sugars being ethanol fermentable. Therefore, Enteromorpha could be a good candidate for production of fuel ethanol. In future work, the effects of temperature and biomass concentration on hydrolysis, and also the fermentation of the hydrolysates to ethanol fuel should be focused on.

Control of Quackgrass in Grasslands Using Different Mechanical Weeding Strategies

It is well known that quackgrass is both very aggressive and persistent. In agriculture, many attempts have been made to eliminate this weed without success. Within the context of a sustainable agriculture, mechanical control of quackgrass represents an interesting alternative to chemical means. The use of a ＂C＂ shaped mounted tine cultivator, a rotary cross-harrow, and an ＂S＂ shaped trailed tine cultivator （alone or in combination） to control quackgrass in grassland was investigated. The rate of quackgrass present in each experimental plot was determined before and after the treatments using a one square meter quadrant. Also, the time required for each passage as well as the fuel consumption were computed. Results revealed that the fuel consumption and the time required by the ＂C＂ and ＂S＂ shaped tine cultivators to transport and expose the rhizomes to the sun on the soil surface highly depend on the quality of tillage during the first stubble passage. Also, subsequent tillage with the ＂C＂ shaped tine cultivator after a first passage with a rotary cross-harrow resulted in less fuel consumption and passage time. On the other hand, stubble and subsequent soil tillage with only the ＂C＂ shaped tine cultivator is the least successful method.

An innovative method to calculate oxygen consumption rate

Based on heat and mass transfer characteristics of spontaneous combustion of coal,Arrhenius equation and the Ranz-Marshall correlation,a novel approach was proposed in this paper to estimate oxygen consumption rate of self-ignition of coal at high temperature.Compared with the conventional methods,this approach involves not only kinetic properties of self-ignition of coal and temperature,but also the ambient air flow characteristics and diameter of coal particle.To testify the proposed approach,oxygen consumption rates at high temperature were measured by the programmable isothermal oven experiments.Comparisons between experimental and theoretical results indicate that the rates of oxygen depletion calculated by the proposed approach agree well with those measured from laboratory-scale experiments,which further validates the proposed approach.

Short-Wave Emission and Microdischarges during Self-Propagating High-Temperature Synthesis

Emission in the X-ray and ultraviolet （200-300 nanometers） region of spectrum is found out during combustion of heterogeneous systems with the formation of condensed products, and pulses from microwave emission with short duration are recorded as well. Combustion of a Ti-B powder system showed that self-propagating high-temperature synthesis （SHS） is accompanied by two types of X-ray radiation. Radiation of the first type has the maximum quantum energy - 5 keV. It is supposed that this type is caused by micro-breakdowns due to the charge separation in combustion products. Runaway electrons and soft X-ray radiation are generated due to the concentration of electric field on microparticles during breakdown. Radiation of the second type has the quantum energy up to - 15 keV. It is supposed that it is caused by exoemission of photons. UV radiation in the region of 200-300 nm is recorded during SHS in different gases （He, Ar, N2）. This radiation is shown to have the highest intensity in helium at the pressure - 25 x 103 Pa.

Optimization of Bacterial Doses and Incubation Time on Bio-Ehanol Fermentation of Nipah （Nypa fruticans） for Biofuel Energy

Nipah （Nypafruticans） is a species of palm trees that grows in mangroves environment near the sea shore. Nipah is potential to produce biofuel energy. The purposes of this research were 1） to determine the optimum bacterial concentration for fermentation to produce high concentration of bio-ethanol, and 2） to determine the optimum incubation time for fermentation to produce high concentration of bio-ethanol. The research had been conducted from June until November 2009 using nipah sap as the substrate and Saceharomyces cerevisiae as a fermentation starter. The experimental design used was a randomized block design （RBD）. Factors tested were starter concentration （5%, 7.5%, 10%） and incubation time （2, 4, 6 days）. The variables observed were concentration of reducing sugar, total microorganism （CFU/mL）, and bio-ethanol production. The results showed that the highest yield of bio-ethanol （8.98%） was produced with 7.5% of starter concentration and 6 days of incubation time.

Preparation and Characterization of Indium Doped Tin Oxide （ITO） via a Solvothermal Method

Tin-doped Indium Oxide （ITO） has been successfully prepared via solvothermal method with a mixture of Indium（Ill） acetylacetonate and Tin（IV） bis（acetylacetonate）dichioride in oleyamine solvent under the condition of the different reaction time from 12 h to 48 h for the first time. The morphology, phase composition and particle size of the ITO powder were characterized by TEM and XRD. Two significant properties required for ITO samples to become noncarbon support for Pt in PEMFCs including specific surface area and electrical conductivity were studied.

Applicability of Waterside Corrosion Models in Range of IFPE Database

Fuel rod cladding waterside corrosion is one of the phenomena that limit the life time of nuclear fuel. Corrosion performance depends on the cladding material properties as well as operating conditions during the irradiation of the fuel. As a function of temperature, power history, water chemistry, time, etc., waterside corrosion is of great concern in fuel performance evaluation, especially for high burnup fuels. This paper is dedicated to the study of the waterside corrosion phenomenon using the IFPE database by COPERNIC, which is developed for the analysis of fuel rod behaviors in normal operation and transient conditions. Different models, MATPRO, FRAMATOME and EPRI models, for example, are adopted in the simulations. The results derived from the models are compared and the unconformities are analyzed. Based on the comparative analysis, reasonable models are chosen to simulate certain irradiated fuel rods. Our analyses indicate that potential affecting factors which are not considered in COPERNIC code, such as water chemistry and alloy composition, should be responsible for discrepancies of certain rod predictions.

Time Series of Combustion Characteristics and Particulate Emission during Combustion of Thai Lignite in a Fixed Bed

The combustion characteristics and particulate emission during combustion of Thai lignite with 30% of secondary air to total air （SA：TA） in a fixed bed combustor have been investigated in real-time. The results have shown that particle formation is governed by competing reaction between the formation of the nucleated sized-particles （Dp 〈 0.1μm） and the coagulated particle （Dp 0.1-1 μm）. Temperature and burning rate are the highest priority factors to control the emission of particulate. Furthermore, the co-firing of coal/rice husks at 60：40% mass fraction with 10%SA：TA could be the alternative options to further reduction of particulate and to be recommended.

Simulation of Biogas Production from Solid Organic Wastes

The design and building of new alternative fuel plants is an increasing necessity to replace old technology and non-renewable fossil fuels. To optimize the performance of these plants and to obtain an economically feasible production of these types of fuels, it is necessary to have a total control of each variable involved in the process of production and how these factors affect the yield of fuel production. In this paper it is proposed a model of a digester to generate gas using a Vensim software designed to generate simulations in dynamic state. This simulation was developed using differential equations to model the behavior at each stage of the process and auxiliary conditions to complement the mathematical description of the model. The main factors in the biogas production are the retention time and the methanogen mortality ratio. For retention time lower than 10 h the process loses effectiveness due to bacterial growth is not completed efficiently, but a high retention time involves a bigger reactor and the yield of production decreases considerably for retention time higher than 40 h. The best yields were obtained for a mortality ratio in methanogen and acidogenic bacteria lower than 0.2 and a retention time of 30 h with a final production of 3.33 L by each kilogram of biomass.

Analysis of NO_X Emission Characteristics of Pulverized Coal Combustion in Different Atmosphere

Researches on the NOx emission characteristics of HT （Huangtai coal）, LC（Laicheng） coal are carried out in different atmosphere. The results show that the NOx emission time is postponed in O2/N2 atmosphere mixed with CO. The releasing times of volatile nitrogen and char nitrogen approach, the amount of NOx reduces. In high 02 concentration atmosphere mixed with CO2, the nitrogen releasing times cane ahead of time, NOx congregate in the beginning of the combustion. On the contrary, nitrogen releases separately, and the amount of NOx reduces greatly.

Risk of North Pole Route on Suez Canal Revenue

The inauguration of the North Pole route as an alternate route for transporting cargoes between the Far East and Europe appears to be extremely acceptable by shipping companies owing to the huge saving in fuel consumption, bunker cost, operating cost, emissions and journey time. This route conversion will not only have an impact on the maritime business activity in the Suez Canal, but also the Egyptian economy in several aspects when the number of vessels passing through the Suez Canal and the Indian Ocean decreases. The aim of this study is to analyze the impact of the opening of the Northern Sea route on maritime sector of the Egyptian economy. The scope of this study is concentrating on the Suez Canal shipping activity by using the statistics that have been received from Suez Canal Authority through a set of direct and indirect interview sessions with authority＇s experts.

Effect of heat transfer space non-uniformity of combustion chamber components on in-cylinder soot emission formation in diesel engine

Combustion chamber components （cylinder head, cylinder liner, piston assembly and oil film） are treated as a coupled body. Based on the three-dimensional numerical simulation of heat transfer of the coupled body, a coupled three-dimensional calculation model for the in-cylinder working process and the combustion chamber components was built with domain decomposition and boundary coupling method, in which the coupled three-dimensional simulation of in-cylindcr working process and the combustion chamber components was adopted. The simulation was applied in the influence investigation of the space non-uniformity in heat transfer among combustion chamber components on the generation of in-cylinder emissions. The results show that the space non-uniformity in heat transfer among the combustion chamber components has great influence on the generation of in-cylinder NOx emissions. The heat transfer space non-uniformity of combustion chamber components has little effect on soot formation, and far less effect on soot formation than on NOx. Under two situations of different wall temperature distributions, the soot in cylinder is different by 1.3% when exhaust valves are open.