Three-Dimensional Study of the Effect of the Angle of Incidence of a Magnetic Field on the Electrical Power and Conversion Efficiency of a Polycrystalline Silicon Solar Cell under Multispectral Illumination

A three-dimensional approach to the effect of magnetic field incidence angle on electrical power and conversion efficiency is performed on a front-illuminated polycrystalline silicon bifacial solar cell. A solution of the continuity equation allowed us to present the equations of photocurrent density, photovoltage and electric power. The influence of the angle of incidence of the magnetic field on the photocurrent density, the photovoltage and the electric power has been studied. The curves of electrical power versus dynamic junction velocity were used to extract the values of maximum electrical power and dynamic junction velocity and to calculate those of conversion efficiency. From this study, it is found that the conversion efficiency values increase with the angle of incidence of the magnetic field.

Temperature Effect on Light Concentration Silicon Solar Cell’s Operating Point and Conversion Efficiency

It is well known that temperature acts negatively on practically all the parameters of photovoltaic solar cells. Also, the solar cells which are subjected to particularly very high temperatures are the light concentration solar cells and are used in light concentration photovoltaic systems (CPV). In fact, the significant heating of these solar cells is due to the concentration of the solar flux which arrives on them. Light concentration solar cells appear as solar cells under strong influences of heating and temperature. It is therefore necessary to take into account temperature effect on light concentration solar cells performances in order to obtain realistic results. This one-dimensional study of a crystalline silicon solar cell under light concentration takes into account electrons concentration gradient electric field in the determination of the continuity equation of minority carriers in the base. To determine excess minority carrier’s density, the effects of temperature on the diffusion and mobility of electrons and holes, on the intrinsic concentration of electrons, on carrier’s generation rate as well as on width of band gap have also been taken into account. The results show that an increase of temperature improves diffusion parameters and leads to an increase of the short-circuit photocurrent density. However, an increase of temperature leads to a significant decrease in open-circuit photovoltage, maximum electric power and conversion efficiency. The results also show that the operating point and the maximum power point (MPP) moves to the open circuit when the cell temperature increases.

Polycrystalline Silicon Solar Cell p-n Junction Capacitance Behavior Modelling under an Integrated External Electrical Field Source in Solar Cell System

The state of the p-n junction is very important to explain the performances of a solar cell. Some works give the influence of the electric field on the junction capacitance. However, these works do not relate the quality of the p-n junction under the electic field. The present manuscript is about a theoretical modelling of the p-n junction capacitance behavior of the polycrystalline silicon solar cell under an integration of the external electrical field source. An external electrical source is integrated in a solar cell system. The electronic carriers charge generated in the solar cell crossed mainly the junction with the great strength external electrical field. In open circuit, this crossing of the electronic charge carriers causes the thermal heating of the p-n junction by Joule effect. The p-n junction capacitance plotted versus the junction dynamic velocity and the photo-voltage for different external electrical fields. The electric field causes the decrease of the photo-voltage mainly the open-circuit photo-voltage. The decrease of the photo-voltage translates the narrowing of the Space Charge Region (SCR). The average value of the external electric field used in this study is not sufficient to cause the breakdown of the p-n junction of the solar cell system under integration of the external electrical field production source. The increase of the electrical field causes rather the narrowing of the SCR. That can provide an improvement of the solar cell’s electrical outputs.

电能高效高质转化技术与创新

电能转化是将电能转化为电能、磁能、热能、声能、光能等其他能量形式,是能源消费的核心基础,已渗透至经济发展和国防建设各个领域。电能高效高质转化技术作为绿色化、精细化能源消费革命的主体与核心技术,是国民经济和国防系统发展的基础、核心竞争力和综合实力的关键标志之一,也是国防和工业领域的“供能心脏”,对于推动我国能源低碳革命意义重大。我国电能转化技术与装备已取得了世界瞩目的成果,但仍存在工业电耗较高、装备卡脖子、国防有短板、基础研究薄弱等问题。为此,结合当前主要能源消费形式,重点梳理电能到电能、磁能、热能、声能、光能5种电能转化形式的基本原理、关键技术及发展现状,总结电能高效高质转换面临的难题及其发展对策,期望能够为我国电能转化技术与装备的发展提供一定参考。

压缩空气储能技术及工程发展概述

针对压缩空气储能技术的飞速发展和不断更新,该文详细介绍压缩空气储能技术的发展历程和各阶段的工程实例,给出各个路线的工艺系统,指明技术特点。蓄热式压缩空气储能技术具备大容量长时储能的属性,是我国大力发展的主流技术,目前正朝着300 MW容量等级方向发展,在建和拟建多个商业工程。随着关键组件制造能力的提升、设备和工质投资的减少,压缩空气储能必将朝着更大容量和更高参数的方向发展,并且会与更多系统耦合,具备更多的应用场景。

空间高温区自由活塞斯特林发电机工作特性试验研究

测试了不同冷端温度下,外负载、运行压力和加热功率对高温区自由活塞斯特林发电机的热端温度、电电效率、输出功率、频率的影响。研究结果表明,在同一冷端温度时,加热功率的增加使发电机的电电效率、输出功率、热端温度上升,而外负载、运行压力的增加则起相反作用;发电机的频率与外负载呈负相关变化,与运行压力、加热功率呈正相关变化。提升冷端温度使发电机的输出功率、电电效率和频率下降,热端温度上升。在三种不同冷端温度下,外负载、加热功率和运行压力对发电机输出特性的影响规律不变。经过测试,发电机在运行温区为495~1058 K时,最大输出功率103.681 W,电电效率20.5%。

重型柴油机排气电加热NO_(x)排放控制技术研究

为解决重型柴油机在冷起动工况下的NO_(x)排放恶化问题,基于重型柴油机冷起动试验平台,自主设计了排气电加热系统,并研究了不同电加热功率对后处理后的NO_(x)排放和每度电可处理的NO_(x)排放的影响.结果表明:随着电加热功率从2 kW升高至8 kW,NO_(x)排放逐渐降低,每度电可处理的NO_(x)排放逐渐升高;电加热功率固定为8 kW时,NO_(x)排放达到最低(140.3 mg/(kW·h)),相比原机减少了51.55%;电加热功率固定为2 kW时,每度电可处理的NO_(x)排放最多为1 900.8 mg.基于此,通过仿真进行排气电加热器控制策略的开发,控制策略引入NO_(x)转化效率和燃油消耗量作为判据,每度电可处理的NO_(x)排放增加了19.27%.此时,仅消耗0.21 kW·h电能,即可将后处理后的NO_(x)排放从274.76 mg/(kW·h)降低至231.42 mg/(kW·h).

电动挖掘机电液系统建模与控制技术研究

以电动挖掘机电液系统为研究对象,首先建立包含永磁同步电机系统以及多执行器液压系统在内的电动挖掘机电液集成模型;其次针对变转速电机+定量液压泵的动力形式,设计了基于模糊比例-积分-微分(PID)的主控电机变转速控制方法。典型工况下的仿真结果表明:提出的电液控制系统具有较好的稳定性和灵敏性,同时与定转速电机+变量泵系统相比,整体节能到达40%以上。

集成互注入半导体激光器的微波光子学应用

光源是微波光子(microwave photonic,MWP)系统的“发动机”,从根本上决定了系统性能的上限。光注入半导体激光器集聚诸多优势,但离散器件引发的系统集成度低、结构复杂、体积大、稳定性差等弊端明显,大大限制了MWP系统的工程化应用。集成化是解决目前MWP技术实用化等瓶颈问题的关键,轻量级、高性能、多功能的激光器光源是集成MWP系统的关键。基于此,本文综述了近年来集成互注入半导体激光器在高效电光转换、微波信号产生、MWP变频、弱信号探测以及光学频率梳源等MWP应用方面的创新研究,期望为集成MWP系统提供可行的高性能集成光源,推动集成MWP技术的工程化应用尽快实现。

压缩空气储能系统电-电转换效率参数敏感性分析

压缩空气储能是在燃气轮机技术的基础上发展起来的一种大型储能技术,是目前除了抽水蓄能之外技术最为成熟的物理储能,如何提高压缩空气储能系统的转换效率,进一步降低储能的成本,是目前研究的重点方向。通过热平衡仿真软件EBSILONProfessional,建立了压缩空气储能系统热力系统模型,对影响压缩空气储能系统电-电转换效率的主要参数进行了敏感性分析,给出了参数优化的方向和建议。

胶体CdSe量子点敏化TiO_(2)太阳能电池中光电转换行为研究

以NaSeH_(4)水溶液、Cd^(2+)水溶液及巯基乙酸为原料采用水热法制备了水溶性CdSe量子点(QDs),并直接敏化在TiO_(2)光阳极上用于量子点敏化太阳能电池(QDSSC)。通过NaSeH_(4)的用量实现了CdSe QDs的尺寸调节和光谱响应范围调控。光伏性能分析表明尺寸约6nm的CdSe QDSSC效率达到2.26%,明显高于尺寸约4nm和10nm的CdSe QDSSC效率(分别为0.62%和1.39%)。光谱和阻抗分析表明合适的CdSe QDs尺寸能扩大光捕获效率并减少光阳极-电解液界面间的电荷复合,从而提高了光电转换效率。

基于模型分析法的电驱往复式天然气压缩机节能优化研究

目前,电驱往复式压缩机因其压力范围广、机组效率高、故障率低的特点,被越来越广泛地应用到油气生产中。但由于其生产特性,每一次启停所带来的成本消耗及能源消耗十分巨大。加之其生产的连续性要求,不便于频繁启停及调整生产工况,从而限制了节能方案效果的有效验证。针对此问题,提出一种基于模型分析法的提效策略,通过构建仿真模型模拟压缩机组运行工况,并通过与实际运行参数进行对比验证确保模型准确性,从而实现通过模型仿真来验证压缩机组提效方案的节能效果,通过三种方案对比,采用余隙无级调节更节电。为电驱往复式天然气压缩机的节能优化提供了科学依据。

链式热氧化与槽式碱抛光工艺条件对PERC单晶硅太阳电池光电转换效率的影响

针对PERC单晶硅太阳电池制备工艺中3合1工序的链式热氧化工艺的氧化性能与槽式碱抛光工艺酸洗槽的去氧化能力的工艺窗口及匹配性进行了研究。首先设计实验分别测试链式热氧化工艺条件(包括温度、氧气流量)、槽式碱抛光工艺的酸洗槽液体浓度对扩散后硅片表面掺杂浓度及PERC单晶硅太阳电池光电转换效率的影响;再根据初步实验结果对链式热氧化工艺与槽式碱抛光工艺的匹配性进行分析,得到整体3合1工序的优化工艺方案;然后采用电化学微分电容电压(ECV)测试扩散后硅片表面掺杂浓度及结深的变化情况,对研究结果进行了佐证,最终达到提升PERC单晶硅太阳电池光电转换效率的目的。研究结果表明:3合1工序中的链式热氧化工艺与槽式碱抛光工艺对扩散后硅片表面掺杂浓度及PERC单晶硅太阳电池电性能存在重要影响,优化链式热氧化工艺的温度、氧气流量与槽式碱抛光工艺的酸洗槽液体浓度,提高二者的匹配性,使氧化能力与去氧化能力均达到临界点,可以最大程度地提高PERC单晶硅太阳电池的光电转换效率。

High conversion efficiency of pristine TiO_2 nanotube arrays based dye-sensitized solar cells

We prepared highly-ordered titanium dioxide nanotube arrays (TNAs) by anodizing Ti foils in F-containing electrolytes.The crystalline nature and morphology of the TNAs were studied using X-ray diffraction patterns and scanning electron microscopy.We found the morphology of TNAs affects the light-to-electricity conversion efficiency (η) of dye-sensitized solar cells (DSSCs).The efficiency of DSSCs reached 5.95% under the condition of light illuminated from the counter electrode.The high efficiency of TNA-based DSSCs was attributed to the neat top surface of TNAs,which allows more dye molecule loading on the surface of the TiO 2 nanotubes,and fewer electron recombination centers and a low interface resistance of integrated TNAs.

Macro-performance of multilayered thermoelectric medium

The effective properties of thermoelectric composites are well known to depend on boundary conditions, which causes the macro performance of thermoelectric composite to be difficult to assess. The overall macro-performance of multilayered thermoelectric medium is discussed in this paper. The analytical solutions are obtained, including the heat flux, temperature, electric potential, and the overall energy conversion efficiency. The results show that there are unique relationships between the temperature/electric potential and the electric current/energy flux in the material, and whether the material is independent of or embedded in thermoelectric composites. Besides, the Peltier effect at the interface can significantly improve the overall energy conversion efficiency of thermoelectric composites. These results provide a powerful tool to analyze the effective behaviors of thermoelectric composites.

Improvement of the Silicon Solar Cell Performance by Integration of an Electric Field Source in the Solar Cell or Solar Module System

This manuscript is about a theoretical modelling of conversion efficiency improvement of a typical polycrystalline Si solar cell in 1D assumptions. The improvement is brought by the increase of the collection of the minority carriers charge in excess. This increase is the consequence of the influence of an electric field provided by the use of the open circuit photovoltage of another silicon solar cell. We assume that it is integrated two silicon solar cells to the system. The first solar cell provides the open circuit photovoltage which is connected to two aluminum planar armatures creating a planar capacitor. The second solar cell is placed under the uniform electric field created between the two aluminum armatures. This work has shown an improvement of the output electric power leading to the increase of the conversion efficiency. We observe an increase of 0.7% of the conversion efficiency of the second silicon solar cell.

组分阶梯InGaN势垒对绿光激光二极管光电性能的影响

为探究不同铟(In)组分In_(x)Ga_(1-x)N势垒对绿光激光二极管光电性能的影响,本文采用SiLENSe(simulator of light emitters based on nitride semiconductors)仿真软件对一系列具有不同In组分In_(x)Ga_(1-x)N势垒的激光二极管进行研究,结果发现In_(x)Ga_(1-x)N势垒中In组分最佳值为3%,此时结构的斜率效率最高,内部光学损耗最低,光学限制因子最大,性能最优。在具有In_(0.03)Ga_(0.97_N势垒的多量子阱结构基础上,设计了一种组分阶梯(composition step-graded,CSG)InGaN势垒多量子阱结构,提高了激光二极管的斜率效率和电光转换效率,增加了光场限制能力。仿真结果表明,当注入电流为120 mA时,具有CSG InGaN势垒的多量子阱结构,电光转换效率从17.7%提高至19.9%,斜率效率从1.09 mW/mA增加到1.14 mW/mA,光学限制因子从1.58%增加到1.62%。本文的研究为制备高功率GaN基绿光激光二极管提供了理论指导和数据支撑。

液态空气储能与液态CO_(2)储能技术对比

为了解决压缩空气储能储气室容积大、成本高的问题,液态空气储能和液态CO_(2)储能得到了国内外广泛关注及研究。针对这两大储能系统,借助ASPEN PLUS软件搭建了热力学物理模型,并借助分析对两大储能系统进行热力学和关键参数敏感性研究分析。研究表明:液态空气储能系统损失主要发生在压缩机及蓄热蓄冷装置上,分别占比45.02%、37.61%。液态CO_(2)储能系统损失主要发生在低温膨胀机、压缩机及蓄冷蓄热装置上,分别占比26.99%、23.88%、30.41%。从电-电转化效率方面:在绝热条件下,两大储能系统由于在充放电过程能量消耗大,电-电转化效率都低于55%,相比液态空气储能,液态CO_(2)储能效率高。从系统成熟度方面:液态空气储能已得到工程应用,而液态CO_(2)储能还处于研究阶段,未得到工程化应用。从投资成本方面;液态CO_(2)储能单位千瓦投资成本高于液态空气储能约40%。

1060 nm锑化物应变补偿有源区激光二极管仿真及其性能研究

本文设计了GaAs基1060 nm高性能激光二极管的有源区结构,通过在有源区中引入锑化物的应变补偿结构GaAsP/InGaAs/GaAsSb/InGaAsSb/GaAsP,改变了有源区的能带结构,解决了禁带宽度对发光波长的限制,将弱Ⅱ型的量子阱能带结构变为Ⅰ型,增大了电子空穴的波函数重叠,提高了激光二极管跃迁概率和辐射复合概率及内量子效率,降低了非辐射复合,有效增强了器件输出功率和电光转换效率。同时,设计了非对称异质双窄波导结构,p侧采用导带差大、价带差小的AlGaAs作为内、外波导层,有利于价带空穴注入有源区且对导带中的电子形成良好的限制。n侧采用导带差小、价带差大的GaInAsP作为内、外波导层,有利于导带电子的注入且对价带中的空穴形成更高的势垒。电子注入势垒和空穴注入势垒分别由原先的218、172 meV降低到148、155 meV,提高了激光二极管的载流子注入效率;电子泄漏势垒和空穴泄漏势垒分别由252、287 meV上升到289、310 meV,增强了载流子限制能力。最后获得的激光二极管的输出功率和电光转换效率分别达到了6.27 W和85.39%,为制备高性能GaAs基1060 nm激光二极管提供了理论指导和数据支撑。

基于1-3压电复合材料宽带超声换能器研究

电声转换效率与换能器带宽是评价聚焦超声换能器性能的重要指标。传统压电陶瓷制备的聚焦超声换能器,其电声转换效率与换能器带宽偏低。该文采用实验结合仿真模拟的方式,通过研究1-3压电复合材料中压电相的体积比、环氧相改性、调控匹配层阻抗与匹配层厚度对换能器性能的影响,开发了一种基于1-3压电复合材料的聚焦超声换能器,实现了82.3%的电声转换效率与140 kHz的换能器带宽。结果表明,与同等规格的传统压电陶瓷聚焦超声换能器相比,该超声换能器的两项指标分别提升了105%与250%,这为大功率聚焦超声换能器的设计开发提供了参考与指导。