砷化镓基系Ⅲ-Ⅴ族化合物半导体太阳电池的发展和应用(1)

介绍以直接带隙Ⅲ-Ⅴ族材料为主体的多结叠层聚光太阳电池的特性和研发进展。据报道,三结叠层GaInP/GaAs/Ge太阳电池已成为空间能源的主力军,四结叠层GaInP/GaAs/GaInPAs/GaInAs聚光太阳电池的效率已达46.5%。在不远的将来,实现高效(50%)、低成本的Ⅲ-Ⅴ族多结叠层聚光电池是有现实可能的。     

QE测量在GaInP/GaAs叠层电池研究中的应用

该文介绍量子效率测量(QE测量)的原理以及此项技术在太阳电池研究中的应用.重点介绍QE测量在GaInP/GaAs叠层电池研究中的应用.给出了作者在美国Toledo大学进行的GaInP/GaAs叠层电池的QE测量的部分结果,并把这些结果与非晶硅(a-Si)三结叠层电池的QE测量结果进行了比较,对GaInP/GaAs叠层电池研究中的问题进行了分析,提出了改进的意见.     

用于高效级联太阳电池的ZnSe材料研究

研究了用于高效Znse／GaAs/Ge(硒化锌绅化镓／锗)级联太阳电池顶电池的ZnSe材料。用MBE技术制备了ZnSe p-n结样品，测量了其外量子效率；提出了改进ZnSe顶电池性能的方法；分析了ZnSe／GaAs／Ge结构比GaInP／GaAs／Ge结构的优越之处。     

多结太阳电池减反射膜的优化

基于多层膜的光学计算基本原理,模拟分析多结化合物太阳电池减反射膜的反射谱。模拟结果准确的反应了实际测量结果。以此为基础设计优化Ti O_x/Al_2O_3/MgF_2三层减反射膜,在GaInP/In_(0.01)GaAs/Ge三结太阳电池上实现了减反射膜对子电池响应电流的精确调节,并得到了子电池电流匹配的GaInP/In_(0.01)GaAs/Ge太阳电池,短路电流密度相比制备减反射膜前提升35.84%。     

砷化镓基系Ⅲ-Ⅴ族化合物半导体太阳电池的发展和应用(7)

<正>2014年,天津三安光电公司报道,他们成功研发了晶格应变三结叠层GaInP/GaInAs/Ge高倍聚光电池,并进行了规模生产,聚光电池效率达到40%~41%。在青海神光格尔木建立了50 MW高倍聚光光伏电站,在青海日芯建立了60 MW高倍聚光光伏电站~([29])。3.3.3反向应变GaInP/GaAs/GaInAs三结叠层聚光电池改善GaInP/GaAs/Ge叠层电池能带匹配的     

GaInP薄膜KMC生长并行计算模拟与可视化研究

以金属有机化学气相沉积(MOCVD)技术在GaAs衬底上生长GaInP太阳电池薄膜材料为对象,将MOCVD反应室内气体热流场CFD数值模拟的结果作为生长参数,运用动力学蒙特卡罗(KMC)方法对GaInP薄膜生长过程进行了并行计算模拟,给出了数据分布方式和通信优化策略进行负载平衡并降低通信开销,实现了真实沉积条件下基于大规模粒子的薄膜生长仿真,解决了单机计算能力的不足,缩短了仿真计算时间。模拟结果与试验一致性较好,为优化MOCVD生长GaInP薄膜的工艺参数提供理论依据,对于使用MOCVD生长高质量薄膜材料的太阳电池具有现实意义。     

GaInP/GaAs/InGaAs倒装三结太阳电池设计与优化

为获得带隙组合对太阳光谱有效的分割利用,基于细致平衡原理,结合p-n结形成机理,应用Matlab语言对GaInP(1.90eV)/GaAs/InGaAs倒装结构电池体系底电池带隙和各子电池厚度进行模拟优化。结果表明底电池带隙为1.0eV时,光电转换效率最高。通过对GaInP(1.90eV)/GaAs(1.42eV)/InGaAs(1.0eV)倒装结构三结太阳电池各结厚度进行优化,综合考虑材料成本及生产技术等因素,最佳厚度组合为1.35、2.83和3.19μm时,光电转换效率为44.4%,仅比最高转换效率低0.3%。     

砷化镓基系III-V族化合物半导体太阳电池的发展和应用(9)

正4.3半导体键合技术(SBT)制备的四~五结叠层聚光电池2014年9月,德国Fraunhofer太阳能系统研究所等单位报道,他们采用SBT研制的四结叠层GaInP/Ga As//GaInPAs/GaInAs聚光电池在324倍AM 1.5D光强下,达到了当前国际最高电池效率46.5%(5.42 mm~2)~[2]。四结电池分两步制备。首先在GaAs(晶格常     

外量子效率测试在GaInP/GaInAs/Ge三结太阳电池接收器性能评估中的应用

利用太阳电池量子效率测试系统对GaInP/GaInAs/Ge三结太阳电池接收器进行检测和分析,从而修补了系统缺陷,对外量子效率测试中发现的问题进行了初步探索和解决。借助GaInP/GaInAs/Ge三结太阳电池的等效电路模型,根据三结结构中各个子电池的短路电流值、调整偏置光和偏置电压,改进了测试中的偏置滤光片问题,提出了该太阳电池接收器的性能评估方法和判断依据。     

砷化镓基系Ⅲ-Ⅴ族化合物半导体太阳电池的发展和应用(3)

<正>2GaAs单结太阳电池2.1 AlxGa1-xAs/GaAs单结太阳电池在上世纪60年代,人们由Ga As材料的优良性质预见到,GaAs太阳电池能获得高的转换效率。但是初期用研制Si太阳电池的扩散p-n结方法来研制GaAs太阳电池并未获得成功。原因是GaAs材料的表面复活速率大,大部分光生载流子被表面复合中心复活,不能形成光生电流。     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

NEXT GENERATION ENGINEERED MATERIALS FOR ULTRA SUPERCRITICAL STEAM TURBINES

正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%.     

Contents in Volume 23,2014

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Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Assessment methods of material ageing using Sdobyrev''s creep rupture model

The physical aspects of the activation energy, in higher and high temperatures, of the metal creep process were examined. The research results of creep-rupture in a uniaxial stress state and the criterion of creep-rupture in biaxial stress states, at two temperatures, are then presented. For these studies creep-rupture, taking case iron as an example the energy and pseudoenergy activation was determined. For complex stress states the criterion of creep-rupture was taken to be Sdobyrev's, i.e. σ_red = σ₁ β + (1 − β)σ_i, where: σ₁-maximal principal stress, σ_i-stress intensity, β-material constant (at variable temperature β = β(T)). The methods of assessment of the material ageing grade are given in percentages of ageing of new material in the following mechanical properties: 1) creep strength in uniaxial stress state, 2) activation energy in uniaxial stress state, 3) criterion creep strength in complex stress states, 4) activation pseudoenergy in complex stress states. The methods 1) and 3) are the relatively simplest because they result from experimental investigations only at nominal temperature of the structure work, however, for methods 2) and 4) it is necessary to perform the experimental investigations at least at two temperatures.     

Production of hydrogen from sewage biosolids in a continuously fed bioreactor: Effect of hydraulic retention time and sparging

Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H₂ kg⁻¹ VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min⁻¹ successfully prevented a decline in hydrogen production and resulted in a yield of 27.0  L H₂ kg⁻¹ VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production.     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.