槽式太阳能集热系统的实验研究

本文设计搭建了槽式太阳能集热系统性能测试平台,通过不同工况下的实验测试数据分析了影响槽式太阳能集热系统性能的主要因素;针对槽式集热器的瞬时效率、集热效率及换热器的热损失系数展开了实验测试与分析计算,讨论了工质流量变化对槽式集热系统性能的影响规律。实验结果表明:晴朗天气瞬时集热效率在0.35～0.65范围内变化,换热器热损失系数在1 W/(m~2·℃)以下,研究结果为槽式太阳能集热系统大规模应用提供一定参考价值。     

变面积槽式太阳能卡琳娜循环热力性能研究

本文研究了变面积槽式太阳能卡琳娜循环的热力性能,用以解决低辐照无法利用以及变辐照条件下卡琳娜循环变工况运行的问题。新系统主要包括两部分:可变镜面积抛物槽式太阳能集热器和可变流程卡琳娜循环。随太阳辐照强度减小,集热温度不变,透平入口温度不变,通过改变扩展聚光镜有效集热面积,维持集热量不变,减少变工况运行;当扩展聚光镜已经全部展开至主聚光镜两侧,而太阳辐照强度继续减小,需降低集热温度和传热介质进出口温差,降低透平入口温度,调整卡琳娜循环流程和主要参数。结果表明,新系统能够增大可利用的太阳辐照强度范围,维持集热场有效热能不变,减少系统变工况运行。     

吸热管参数对熔盐吸热器性能的影响

塔式太阳能热发电外圆柱式熔盐吸热器的总体尺寸和流量一定时,其性能主要取决于吸热管的结构参数。利用Fluent软件,通过对不同管径、壁厚的熔盐吸热管的传热特性的模拟分析,揭示吸热管结构参数对吸热器性能的影响规律。结果显示,吸热管直径在15 mm至20 mm之间时,吸热器具有较好的综合性能;吸热管外壁面温度随壁厚的增加而急剧增加,导致吸热器的辐射损失和对流损失增加。     

基于TRNSYS的太阳能集热系统能量转化分析与优化

建立了太阳能集热器非稳态数学模型。以工程实例为研究对象,借助于TRNSYS软件,分析不同集热器类型,集热面积,水箱容积,水箱流量对太阳能集热系统性能的影响。优化集热器和水箱设计参数,采用变流量水箱系统,对提高太阳能集热系统综合性能有指导意义。     

抛物槽式太阳能蒸汽发生系统研究

针对600m2抛物槽式太阳能试验台,建立了太阳能蒸汽发生系统的数学模型,开展了模拟研究,并验证了集热场模型的正确性.研究了太阳直射辐射、入射角等因素对系统性能的影响,分析了系统动态特性,利用图像分析(EUD)方法分析了系统的能量转化过程.结果表明,系统集热效率在高温段下降程度加剧;集热效率随太阳入射角的增大而越小,入射...     

抛物槽式太阳能集热器集热实验及模拟研究

本文采用真空集热管在抛物槽式太阳能平台上进行了实验研究,传热工质为YD300型合成导热油。实验测定了该集热管的散热损失,并数值模拟了吸热管表面的能流密度分布。以此为边界条件研究了该集热管的换热性能。结果表明,循环工质温度和环境温度之差为180℃时,散热损失为220 W/m;该集热器吸热管表面圆周方向能流分布集中,流量对温度分布影响较大,当太阳直射辐照为1000 W/m~2,导热油温度为200℃,流量为0.5 kg/s时,吸热管圆周方向最大温差50℃左右,当流量增加到2.0 kg/s时,最大温差减小到20℃左右。     

槽式集热器吸热管外混合对流换热数值模拟

本文总结了太阳能抛物槽式集热器吸热器玻璃管外对流换热的影响因素.在Shiraz 250 kW槽式太阳能热发电系统集热器结构基础上,采用最佳口径比,设计了几种结构参数不同且具有典型意义的集热器;并对所设计不同集热器结构及位置因素影响下的吸热管外混合对流换热进行了数值模拟.模拟结果表明:吸热管外混合对流平均换热热损失随集热器距地距离增大而增大,但增幅越来越小;随集热器两半反射器间间距增大而减小.而不同结构参数下混合对流换热热损失,主要受到风流在不同运行方位下由于集热器阻滞所形成的风流压力场及速度场的影响,且随结构参数呈一定趋势变化.在此基础上进一步可研究吸热器复杂耦合传热过程.     

新型太阳能与燃气轮机联合循环互补系统集热场优化研究

新型太阳能与燃气轮机联合循环互补系统根据不同类型的太阳能集热装置的集热特性,实现其与燃气轮机联合循环系统的梯级互补,将太阳能直接蒸汽发生系统(DSG)与高压蒸汽蒸发过程耦合,同时将低压蒸汽的生成过程与热管式真空管集热器进行耦合。本文主要针对真空管集热场中集热器行间距及倾斜角等参数的优化问题,开展其对全年有效太阳热能及平均集热效率影响规律的研究。     

平板微热管阵列-CPC太阳能空气集热器集热特性

对新型平板微热管阵列-复合抛物面太阳能空气集热器的结构、集热特性,包括时间常数、集热效率及阻力性能进行了理论分析和实验研究。通过实验研究和对集热器性能的分析,得出了该集热器的瞬时效率曲线和阻力特性曲线。研究结果表明,该集热器在春季的平均集热效率在53%左右,在风量60~320 m~3/h的工况下,阻力小于22 Pa。此外,在空气流量为260 m~3/h时,测得该集热器的时间常数约为16 min。     

八达岭太阳能塔式热发电吸热器水动力特性仿真研究

本文以八达岭塔式太阳能热发电实验电站腔式吸热器为研究对象,根据吸热器的结构和工作原理,利用热力学定律建立了吸热器系统水动力仿真数学模型,模拟了吸热器蒸发受热面系统内工质的流动,通过吸热器水动力的仿真实验从而得到在不同的太阳辐照强度下吸热器蒸发受热面入口流量的分配规律。论文结论对实际太阳能热发电站吸热器的设计及安全运行具有指导意义。     

Lattice Boltzmann Simulation for Complex Flow in a Solar Wall

In this letter,we present a lattice Boltzmann simulation for complex flow in a solar wall system which includes porous media flow and heat transfer,specifically for solar energy utilization through an unglazed transpired solar air collector(UTC).Besides the lattice Boltzmann equation(LBE) for time evolution of particle distribution function for fluid field,we introduce an analogy,LBE for time evolution of distribution function for temperature.Both temperature fields of fluid(air) and solid(porous media) are modeled.We study the effects of fan velocity,solar radiation intensity,porosity,etc.on the thermal performance of the UTC.In general,our simulation results are in good agreement with what in literature.With the current system setting,both fan velocity and solar radiation intensity have significant effect on the thermal performance of the UTC.However,it is shown that the porosity has negligible effect on the heat collector indicating the current system setting might not be realistic.Further examinations of thermal performance in different UTC systems are ongoing.The results are expected to present in near future.     

Influence of interface states,conduction band offset,and front contact on the performance of a-SiC:H(n)/c-Si(p)heterojunction solar cells

P-type silicon heterojunction(SHJ) solar cells with a-SiC:H(n) emitters were studied by numerical computer simulation in this paper. The influence of interface states, conduction band offset, and front contact on the performance of a-SiC:H(n)/c-Si(p) SHJ solar cells was investigated systematically. It is shown that the open circuit voltage(V_(oc)) and fill factor(F F) are very sensitive to these parameters. In addition, by analyzing equilibrium energy band diagram and electric field distribution, the influence mechanisms that interface states, conduction band offset, and front contact impact on the carrier transport, interface recombination and cell performance were studied in detail. Finally, the optimum parameters for the a-SiC:H(n)/c-Si(p) SHJ solar cells were provided. By employing these optimum parameters, the efficiency of SHJ solar cell based on p-type c-Si was significantly improved.     

太阳能海水淡化装置的传热研究和性能分析

分析了几种太阳能海水淡化装置工作原理、结构和传热;指出要提高装置的性能参数和产水率,应从加强传热、充分利用潜热、同时减少装置中海水热容量等方面来考虑,但是最主要的是提高太阳能蒸馏器提供热源的温度。上述工作为太阳能海水淡化装置的进一步改进提供参考。     

结构参数对p-i-n结构InGaN太阳能电池性能的影响及机理

研究了器件结构参数对p-i-n结构InGaN单结太阳能电池性能的影响及物理机制. 模拟结果发现: 随着InGaN禁带宽度的增加, InGaN电池的短路电流减小, 但同时开路电压增加, 当InGaN层的禁带宽度为1.5 eV左右时, 同质p-i-n结InGaN电池的效率最高, 并计算了不同厚度的i层对InGaN电池效率的影响. 进一步的计算表明, 适当采用带宽更大的p-InGaN层形成异质p-i-n结InGaN电池可以获得更高效率, 但是p-InGaN层带宽过大也会导致电池的效率急剧下降. 研究还发现, 采用禁带宽度更大的n-InGaN层可以形成背电场, 从而增加p-i-n结InGaN太阳电池的效率. 研究结果表明, 适当选择p-InGaN和n-InGaN禁带宽度形成异质p-i-n结可以提高InGaN太阳能电池效率.     

PIN型和NIP型硅薄膜太阳电池中绒面陷光结构和陷光性能研究

对于硅薄膜太阳电池来说, 无论是PIN型还是NIP型太阳电池, 采用绒面陷光结构来提高入射光的有效利用率是提高太阳电池效率的重要方法之一.本文采用标度相干理论对PIN和NIP型电池的绒面结构的陷光性能进行了数值模拟. 结果表明: PIN电池中前电极和NIP电池中背电极衬底粗糙度分别为160和40 nm时可获得理想的陷光效果; 在不同粗糙度背电极衬底上制备a-SiGe:H电池发现, 使用40和61.5 nm 背电极可获得相当的短路电流密度, 理论分析和实验得到了一致的结果. 关键词： 陷光结构 光散射能力 标量相干理论 硅基薄膜太阳电池     

1.x级溴化锂吸收式制冷循环性能分析

提出了一个适合于利用太阳能的新型1.x级溴化锂吸收式制冷循环。计算了该循环的性能。结果表明,在现有太阳能集热器所能提供的热水温度范围,1.x级循环克服了单效循环运行范围窄的缺点,其性能指标明显高于两级循环;冷却水先进入冷凝器的串联流程优于并联流程;热水、冷媒水、冷却水温度对溴冷机循环系统的性能系数、热源单耗、面积单耗等经济性指标有较大影响。     

Accurate analysis of electron transfer from quantum dots to metal oxides in quantum dot sensitized solar cells

Electron transfer rate from quantum dot (QD) to metal oxide (MO) in quantum dot sensitized solar cells (QDSSCs) has an important role in the efficiency. In this work, we analyse the electron transfer rate from CdSe, CdS and CdTe QDs to TiO₂, ZnO and SnO₂ MOs by extending the related equations with considering various effects, based on the Marcus theory. In this regard, the effects of QD diameter, QD–MO spacing, the crystalline defects, temperature, and the reorganizational energy, on the electron transfer rate are investigated. The results show that, the maximum electron transfer rate is achieved for CdTe QD with the mentioned three MOs. Moreover, in order to direct the designer to reach the appropriate QDs–MOs combinations for obtaining the maximum electron transfer rate, the average electron transfer rate for various combinations is calculated. For the verification of simulation method, a part of work has been compared with the previous experimental and theoretical results, which indicates the correctness of our simulation algorithm.     

Performance and Exergy Analyses of a Solar Assisted Heat Pump with Seasonal Heat Storage and Grey Water Heat Recovery Unit

The main research objective of this paper was to compare exergy performance of three different heat pump (HP)-based systems and one natural gas (NG)-based system for the production of heating and cooling energy in a single-house dwelling. The study considered systems based on: 1. A NG and auxiliary cooling unit; 2. Solely HP, 3. HP with additional seasonal heat storage (SHS) and a solar thermal collector (STC); 4. HP with SHS, a STC and a grey water (GW) recovery unit. The assessment of exergy efficiencies for each case was based on the transient systems simulation program TRNSYS, which was used for the simulation of energy use for space heating and cooling of the building, sanitary hot water production, and the thermal response of the seasonal heat storage and solar thermal system. The results show that an enormous waste of exergy is observed by the system based on an NG boiler (with annual overall exergy efficiency of 0.11) in comparison to the most efficient systems, based on HP water–water with a seasonal heat storage and solar thermal collector with the efficiency of 0.47. The same system with an added GW unit exhibits lower water temperatures, resulting in the exergy efficiency of 0.43. The other three systems, based on air–, water–, and ground–water HPs, show significantly lower annual source water temperatures (10.9, 11.0, 11.0, respectively) compared to systems with SHS and SHS + GW, with temperatures of 28.8 and 19.3 K, respectively.     

keV质子辐照Kapton/Al的能量传输过程

采用TRIM和SRIM2003软件模拟计算了10—300keV能量区间质子辐照Kapton/Al的能量传输过程. 依据模拟结果选取了辐照能量参数, 在室温真空条件下, 采用空间综合辐照设备对Kapton/Al进行了质子辐照. 借助于表面红外光谱技术, 对Kapton的重要官能团特征峰做了定量分析, 通过特征峰处吸光度的变化得到了典型分子键的损伤截面. 平均损伤截面和电子能损的强烈依赖关系及TRIM计算结果一致说明keV质子辐照Kapton/Al的辐照损伤主要来自电子能损效应. 太阳吸收比的变化趋势和模拟结果都表明在入射能量80keV附近, 质子辐照Kapton/Al的辐照效应最大.     

Evaluation of the energy spectrum of solar protons according to the balloon measurement data and Monte Carlo simulation

The method for evaluating the energy spectra of solar protons at the boundary of the Earth’s atmosphere according to the data of balloon measurements carried out at the Lebedev Institute of Physics, Russian Academy of Sciences, and the results of Monte Carlo simulation of the processes of proton interaction in the Earth’s atmosphere has been developed. The balloon measurements during solar proton events make it possible to determine the absorption spectra of solar cosmic rays in the atmosphere. Comparison of the experimental data with the results of the simulation of propagation of solar protons (E _p = 10 MeV-10 GeV) in the atmosphere, based on GEANT-4, allows determination of the energy spectra of solar protons at the atmospheric boundary. The results of the determination of the energy spectra of solar protons in a number of solar proton events in the current (23th) solar activity cycle are reported.