冷却剂流量对聚光型太阳能光伏系统效率的影响

针对聚光型太阳能光伏电池工作中温度升高会导致发电效率降低的问题,在太阳能模组上铺设有机工质循环管路对光伏电池进行冷却,通过冷凝器对管内有机工质吸收的热量进行收集利用,构建聚光型太阳能光伏/光热综合利用系统。建立传热模型,计算不同日照强度下模组的输出效率并与实验数据进行对比。实验结果表明:发电效率随日照强度的增加先增加后减小;对光伏电池进行冷却可提升系统输出效率;太阳能光伏发电及散热量利用效率合计可达60%。     

基于纳米流体的光伏热联用装置及其理论分析

利用纳米流体对太阳能辐射分频吸收与高效传热的性能,结合太阳能直接吸收(DAC)技术、菲涅尔聚光技术,构建了基于纳米流体的新型聚光太阳能光伏热联用(CPV/T)装置,并建立了装置的物理模型和能量平衡模型。采用计算流体力学方法进行模拟仿真和对比实验,分析了不同流速及流体工质下光伏组件及纳米流体的温度场。研究结果表明:基于纳米流体的CPV/T装置能够充分利用纳米流体辐射分频吸收与高效传热特性,取得对太阳能光伏组件冷却的更好效果,也获得了更高的光热部分流体出口温度;与仅背板冷却的普通光伏热装置相比,流体出口温度有较大幅度的提升,从而提高了光热部分的利用能级。     

建筑领域太阳能利用系统的性能、挑战及优化策略综述

建筑领域的太阳能利用技术包括太阳能热水系统、太阳能制冷与空调系统、太阳能热泵系统以及建筑一体化光伏/热系统(BIPV/T)。系统效率和储热是制约太阳能热水系统发展的关键因素,目前的研究主要侧重于优化系统效率,未来应进一步关注储热技术的进步,以解决太阳能热水系统热水供应稳定性的问题。太阳能制冷与空调系统重点关注降低太阳能集热系统成本、提高集热器性能并研发小型太阳能制冷设备。太阳能热泵技术具有高能源利用率和低环境污染的特点,目前在实际应用中面临的技术障碍包括系统集成与优化、高效太阳能收集器、热泵性能提升、季节性储能、可靠性与稳定性以及经济性与可扩展性等,其中系统集成与优化尤为关键。太阳能光伏光热综合应用是建筑节能领域的一个重要研究方向,太阳能聚光光伏/光热系统(CPV/T)是解决BIPV/T系统中太阳能利用率低下问题的有效策略。BIPV/T和CPV/T系统还需要深入探讨集热器优化设计、材料选择、气候适应性及可持续性等问题。总之,未来建筑领域太阳能系统利用的主要研究方向为提高系统性能、开发新型材料以及集成优化。此外,应用物联网、大数据和人工智能技术可以促进太阳能系统的智能化监测、控制和维护。     

国内太阳能聚光PV/T系统聚光器的研究进展

介绍了太阳能聚光光伏光热一体化(PV/T)系统聚光器的分类、国内研究现状,分析了目前聚光器设计中的3类曲面形式、聚光方式及其特点、主要材料等关键问题,总结了各类聚光器的数值模拟或实验研究的结果,并对聚光器的发展进行了展望,提出了聚光器的发展方向。     

复合抛物面聚光器（CPC）在光伏/热太阳能系统中的应用及实验

为研究复合抛物面聚光器(compound parabolic concentrator,CPC)在光伏/热(PV/T)太阳能系统中的应用特性,分析CPC-PV/T集热器内部的热传输机理,建立CPC-PV/T太阳能系统的光热、光电能量转换理论。并对系统的光热、光电转换特性进行研究,结果表明,CPC型聚光器在PV/T系统中的应用,一定程度上会导致系统光热转换性能的降低,但能有效提高系统光电转换效率。另外,设计无聚光PV/T太阳能系统样机和CPC型聚光PV/T太阳能系统样机,并对2种样机的光热、光电特性进行测试及对比分析。其中,CPC-PV/T样机的热效率为39.6%、输出电效率5.4%,无聚光PV/T样机热效率为44%、输出电效率仅为4.1%,实验结果与理论分析结果一致。     

采用菲涅尔透镜的太阳能CPV/T系统实验与模拟研究

为了解决光伏板温度过高使光电转换效率下降的影响,搭建了一套基于聚光型菲涅尔透镜的太阳能光伏/光热(CPV/T)系统,菲涅尔透镜的聚光比为5.85,光伏板由蛇形换热通道进行冷却。基于上海气象参数,对该系统进行了实验研究。实验结果表明:实验日内系统的光热效率、光电效率和综合效率分别为50.93%,10.86%,61.79%。同时,利用TRNSYS软件,建立了系统动态能效分析模型,将模拟结果与实验结果进行对比,最大误差仅为3.08%,两者吻合较好。     

太阳能光电/光热一体化技术及其应用进展研究

太阳能光电/光热一体化系统主要由光伏电池组件和太阳能集热器组成,可同时实现光伏发电和光热利用,从而有效地提高了太阳能的综合利用效率。文章首先从光伏组件和光热部件着手,分析了PV/T系统的结构和各项性能;然后,概述了目前常用的PV/T热水系统性能评估方法;最后,提出了在推广PV/T系统时还须解决的问题。     

矩阵型聚光光伏光热一体化系统设计与分析

提出一种新型矩阵型聚光光伏光热一体化系统,基于热管技术,设计并制作热管式光伏光热一体化(PV/T)集热器,具有传热效率高等优点。其次,基于平面镜反射原理,设计矩阵型聚光器,架构简单。为了验证矩阵型聚光器的可行性,在Solid Works三维设计软件中绘制出矩阵型聚光器的三维实体模型,将该实体模型导入Trace Pro中进行光学分析,光学效率达到68.7%,仿真结果表明,本文设计的矩阵型聚光器是合理的、可行的。最后,本文提出聚光光伏光热一体化(c-PV/T)系统的光电光热总效率和光电光热综合效率,综合评价c-PV/T系统的系统性能。     

不同结构PV/T系统散热方式的试验研究

光伏/光热(PV/T)集热器集光伏发电和太阳能低温热利用于一体,既可以提高电池效率,又可以回收和利用低温热能。文章对内置不同冷却结构的PV/T系统和电池板的散热特性进行了对比试验。试验结果表明:回形冷却结构PV/T系统的冷却效果要优于蛇形结构;不同结构PV/T系统的综合效率均大于电池光板的折算综合效率。回形冷却结构的PV/T系统最高综合效率可达40%,而电池板的折算综合效率最高只有14.7%。     

太阳能光电——光热复合系统关键技术研究

采用聚光跟踪光伏发电技术,在相同发电功率等级条件下,光伏电池面积仅为常规的1／5,大大降低光伏发电成本;采用特殊结构和层压技术,研发出具备热交换和温控功能的聚光电池组件,确保晶硅电池片在60℃下工作,解决聚光带来的电池板温升过高而使光电转化效率降低的技术难题,并把聚光电池组件上无法转变成电能的太阳能以热水形式收集起来,再通过高效平板集热器对聚光电池组件热交换器流出的温水进行二次加热,获取80℃以上利用价值高的热水,使得光电光热综合转换效率〉55％。达到太阳能光电一光热综合利用的高效、低成本、实用化效果。     

Design and analysis of a CPV/T solar receiver with volumetric absorption combined spectral splitter

Spectral beam splitting is a promising technology to achieve the maximum electrical and thermal outputs from concentrating photovoltaic/thermal (CPV/T) systems simultaneously. In this article, a novel CPV/T receiver is proposed by incorporating a fluid based filter together with a solid absorptive filter. The geometry of the receiver is developed for a designed linear flat mirror concentrator. According to the optical transmittance of both fluid based filters and solid absorptive filters, as well as their corresponding merit functions, four fluid filters and two solid filters are determined to be the candidates of the combined filter for the silicon concentrator solar cell. Then, a complete solar radiation propagation process from concentrator to the designed CPV/T receiver is simulated using ray tracing software-LightTools. The results show that the surface illumination uniformity of the PV module filtered by each combined filter under the linear flat mirror concentrator is higher than 96%. Using 5 g/L CoSO₄ solution and HB650 as the combined filter, 33.67% of the concentrated light can be directed to the PV module with the remainder collected by the filter as thermal energy and the silicon CPV cells can convert 27.06% of this energy into electrical power. This contributes to the fact that 92.43% of the light striking the PV module is within 650-1100 nm, which is the spectral response range of the cell can work efficiently. The total efficiency of 49.88% can be achieved with such a filter and the electrical efficiency is 9.1% with respect to the total incident power on the receiver.     

Development process of solar photovoltaic system cooling technology

光伏系统在运行时,冷却太阳能光伏电池板使其达到更高的效率是一个关键因素。适当的冷却可以提高电力效率,并随着时间的推移降低电池退化的速度,从而使光伏组件的寿命最大化。综述了传统冷却技术中自然循环对流冷却、强制对流循环冷却和液冷技术,新型冷却技术浮动跟踪集中冷却系统、混合PV/T系统冷却、混合PV/TE系统采用散热器冷却以及通过使用相变材料来提高太阳能光伏电池板的性能。根据研究的重点、贡献和实际应用分析各技术的优缺点、适合应用的领域及各自技术的经济特点。未来的技术发展方向应是无论选择何种技术来冷却光伏板,都应该保持工作表面温度较低且稳定、简单可靠、能够利用提取的热能来提高整体的转换效率。     

Simulation and economic analysis of a CPV/thermal system coupled with an organic Rankine cycle for increased power generation

In concentrating photovoltaic (CPV) systems the incident solar radiation is multiplied by a factor equal to the concentration ratio, with the use of lenses or reflectors. This is implemented, in order to increase the electric power production, since this value has a linear dependence from the incident radiation. Therefore, the specific energy production of the cells (kWh/m²) radically increases, but due to this high intensity CPVs consequently operate at elevated temperatures, because heat dissipation to the environment is not so intense and heat produced cannot naturally convected. This temperature increase not only leads to a reduction of their electric efficiency, but also it must be dissipated, since issues regarding their degradation and reduction of their lifetime might arise. There are many reported ways of removing this heat, either by adding a cooling unit on the back side of the CPV module, or by recovering with possible uses in buildings, industry, additional power production or even desalination of seawater.The current work is actually a feasibility study, concerning a concentrating photovoltaic/thermal (CPV/T) system, where the heat produced is recovered by an organic Rankine cycle (ORC) for additional power production. A pump drives the organic fluid of the cycle, which is evaporated in the tubes of the CPV/T and driven to an expander for mechanical power production. For the condensation of the organic fluid several possible alternatives can be applied. That way, the PV cells can be cooled effectively and increase their electrical efficiency, while the recovered heat is designated to produce additional electric energy through the organic Rankine process, when the expander of the Rankine engine is coupled to a generator.The scope of the present work is to investigate an alternative application of concentrating PV modules through exploiting the generated heat by the ORC process and combining both technologies into an integrated system. The design of the system is presented in details, along with an optimization of some main parameters. The performance of the system will also be examined and compared with an equivalent conventional CPV system, referring to their design points. Finally, the annual and daily performance will be studied, which is a more realistic indicator, concerning the increased efficiency this integrated system is expected to have, followed by a cost analysis, in order to examine its economic feasibility as well.     

小型菲涅尔式CPV/T集热器光热特性研究

为充分利用建筑屋顶,解决光伏光热一体化(PV/T)集热器光电转换效率的高温减益问题,并提高太阳能综合利用率和集热品位,文章构建了一种基于太阳光谱分频利用技术的光伏/光热模块分离式的小型聚光式PV/T集热器。通过建立其光/电/热理论分析模型及TracePro/Fluent数值仿真模型,以南京地区气象数据为例,综合分析其光/电/热性能,结果表明:该集热器以与安装地纬度等值的倾角南北轴向放置时,其年均光学效率为64.97%,工质出口温度为90℃时的系统光电/光热效率分别为12.47%,40.09%,系统综合热效率达72.91%,且其结构简单、外形轻薄,有望实现与普通建筑的有效结合。     

Uniqueness verification of direct solar spectral index for estimating outdoor performance of concentrator photovoltaic systems

To analyze the impact of a direct spectral distribution of the solar spectrum on the outdoor performance of concentrator photovoltaic (CPV) systems, an index for the direct spectral distribution is needed. Average photon energy (APE), the average energy of a photon in the direct solar spectrum, is one of these indexes. In this contribution, the uniqueness of APE to the direct solar spectral distribution is statistically analyzed to assure that an APE value uniquely yields the shape of a direct solar radiation spectrum. The results have exhibited the uniqueness of the direct normal solar spectrum with each APE value, in which the standard deviations are quite small. Short-circuit current density of the InGaP/InGaAs/Ge triple-junction solar cell in the CPV system is additionally calculated using the direct spectral irradiance with different APE values. It is revealed that APE is a useful index to describe the direct spectral distribution to evaluate the outdoor performance of the CPV systems.     

非跟踪低倍聚光热管式真空管集热器的实验研究

太阳能是一种取之不尽用之不竭的清洁能源,但存在分散性强、能量密度低、不稳定等特点,因此为了得到高能量密度和稳定的能量供应,需要解决聚光和储能两大问题。针对这两个问题,本文采用非跟踪低倍聚光的集热器和保温效果良好的储热油箱,提出了一种非跟踪低倍聚光热管式真空管集热器;基于几何光学原理,模拟了热管式真空管和半圆聚光器的不同放置方式和位置的聚光效率,制作了半圆形聚光热管式真空管集热器系统,选择了合适的储热油箱并进行了保温效果的理论计算;最后对该系统进行了集热性能测试实验。实验结果表明,在半圆形聚光器的聚光下,系统的瞬时效率截距为0.66,热损系数为2.53 W/(m2•℃)。该系统完全能够满足人们的日常生活用热的需求,具有良好的应用前景。     

Experimental and numerical studies of a U-shaped solar energy collector to track the maximum CPV/T system output by varying the flow rate

In the last decade, no comprehensive numerical and experimental analyses have been performed to find the maximum possible power generation from a concentrated photovoltaic thermal (CPV/T) system by varying the flow rate of the fluid. This paper describes numerical and experimental studies of a U-shaped solar energy collector model of a CPV/T system, with the goal of determining the maximal thermal and electrical power outputs against a specific volumetric flow rate also called an optimum flow rate. The CPV/T system was based on the union of 8 triple junction solar cells, 8 SOG Fresnel lenses, effective dual-axis tracking, and a forced cooling system. Analyses were performed by changing the flow rate of the working fluid at a considered solar irradiation and ambient temperature. The thermal and electrical power outputs also varied with changes in the ambient temperature and available solar radiation. The relatively high value of CPV/T power was observed against the optimum flow rate at a given irradiation and ambient temperature. Analysis of the energy of the U- shaped solar energy collector system was evaluated experimentally. The numerical results and experimental measurements of the U-shaped solar energy collector model showed great harmony, with minimal deviations of <7% between them.     

Electrical and thermal performance of silicon concentrator solar cells immersed in dielectric liquids

Direct liquid-immersion cooling of concentrator solar cells was proposed as a solution for receiver thermal management of concentrating photovoltaic (CPV) and hybrid concentrating photovoltaic thermal (CPV-T) systems. De-ionized (DI) water, isopropyl alcohol (IPA), ethyl acetate, and dimethyl silicon oil were selected as potential immersion liquids based on optical transmittance measurement results. Improvements to the electrical performance of silicon CPV cells were observed under a range of concentrations in the candidate dielectric liquids, arising from improved light collection and reduced cell surface recombination losses from surface adsorption of polar molecules. Three-dimensional numerical simulations with the four candidate liquids as the working fluids, exploring the thermal performance of a silicon CPV cell array in a liquid immersion prototype receiver, have been performed. Simulation results show that the direct-immersion cooling approach can maintain low and uniform cell temperature in the designed liquid immersion receiver. The fluid inlet velocity and flow mode, along with the fluid thermal properties, all have a significant influence on the cell array temperature.     

Design and analysis of an integrated concentrated solar and wind energy system with storage

This study analyzes a renewable energy‐driven innovative multigeneration system, in which wind and solar energy sources are utilized in an efficient way to generate several useful commodities such as hydrogen, oxygen, desalted water, space cooling, and space heating along with electricity. A 1‐km² heliostat field is considered to concentrate the solar light onto a spectrum splitter, where the light spectrum is separated into two portions as reflected and transmitted to be used as the energy source in the concentrated solar power (CSP) and concentrated photovoltaics (CPV) receivers, respectively. As such, CSP and CPV systems are integrated. Wind energy is proposed for generating electricity (146 MW) or thermal energy (138 MW) to compensate the energy need of the multigeneration system when there is insufficient solar energy. In addition, multiple commodities, 46 MW of electricity, 12 m³/h of desalted water, and 69 MW of cooling, are generated using the Rankine cycle and the rejected heat from its condenser. Further, the heat generated on CPV cells is recovered for efficient photovoltaic conversion and utilized in the space heating (34 MW) and proton exchange membrane (PEM) electrolyzer (239 kg/h) for hydrogen production. The energy and exergy efficiencies of the overall system are calculated as 61.3% and 47.8%, respectively. The exergy destruction rates of the main components are presented to identify the potential improvements of the system. Finally, parametric studies are performed to analyze the effect of changing parameters on the exergy destruction rates, production rates, and efficiencies.