【作者】 陈海飞；

【导师】 季杰；

【作者基本信息】 中国科学技术大学 ， 热能工程， 2014， 博士

【摘要】 太阳能以其清洁、可再生和利用广泛等特点备受瞩目,成为了传统化石能源的替代能源之一。作为太阳能重要利用形式之一的光伏发电技术也已经引起了世界各国的广泛关注。而聚光光伏发电技术通过采用聚光器提高光伏组件表面的能流密度,可以大幅度减少昂贵光伏电池的面积,是提高系统效率、降低系统发电成本的有效途径。针对聚光光伏发电系统能流密度分布不均匀以及光伏组件温度过高等问题,从提高太阳能利用率及降低系统成本的角度出发,结合聚光太阳能光伏发电技术和太阳能光电光热综合利用的思想,本文提出了高倍聚光光伏光电光热综合利用系统,对反射型和折射型两种高倍聚光发电系统分别进行了强制水冷换热设计研究。系统在输出电能的同时对产生的余热进行收集利用,在提高光伏电池光电转换效率的同时还能获得额外的热能收益,大大提高了系统的太阳能综合利用效率。对于两种不同形式的高倍聚光光伏发电供热(HCPV/T)系统,分别建立了相应的动态数学模型以及相应的实验测试平台,通过数值模拟和实验研究相结合的方法,对不同聚光比、不同质量流量以及不同环境参数条件下系统光伏电池的输出特性、聚光光斑能流密度分布的均匀性、系统光电转换和系统光热转换的耦合关系等进行了深入的研究。本文的主要研究内容主要包括以下几个方面：建立了旋转抛物面式高倍聚光器的光学模型,根据系统聚光比及太阳影像等光学理论对该聚光器的聚光焦距、采光面积等进行了理论设计。在此基础上,针对其聚光光斑不均匀的缺点,分别采用化整为零的思想提出了多碟共焦式高倍聚光器；以及通过平面镜分段逐步逼近抛物面的方法,提出了平面镜阵列取代连续曲面的聚光方式。通过相应的理论分析研究,分别搭建了多碟共焦式高倍聚光器实验平台和平面镜阵列高倍聚光器实验平台,并对两者的聚光能流密度分布进行了实验研究。结果表明平面镜阵列高倍聚光器能从根本上解决聚光不均匀的问题。且系统部件不仅加工安装难度小、成本低、稳定性及抗风性能好；而且该系统的聚光比可调节,适用于各种聚光比需求的聚光光伏发电系统。结合平面镜阵列高倍聚光器和CPV/T模块,建立HCPV/T系统的动态数学模型,研究高热流密度下光伏电池与基板、基板与换热器的结构设计,并对模型中光伏基板、换热器以及内部的冷却水沿水流方向的温度分布进行了理论模拟,给出了系统热效率、电效率及光电光热综合效率的计算方法。结合光敏跟踪和视日程序跟踪方法,设计并研制了系统所需的双轴跟踪系统。搭建了平面镜阵列HCPV/T系统实验测试平台,对系统的关键温度参数、热效率、电效率以及光电光热综合效率进行了实验测试以及结果分析。同时深入探讨了不同聚光比、不同质量流量以及不同环境参数等对系统热电性能的影响。实验结果表明,该HCPV/T系统具有良好的光电光热性能,光电效率可达22%,热效率可达47%,光电光热综合效率能够达到70%左右。同时本文还对该平面镜阵列系统的CPV/T模块电输出性能的温度系数作了实验与理论分析。提出了菲涅尔水冷散热HCPV/T系统,并对该系统模型进行了理论研究,对其子部件菲涅尔棱镜的设计及光学性能进行了理论分析。建立了包含系统热模型及电模型在内的菲涅尔水冷系统动态模型。建立了标准状态下的单二极管五参数模型,讨论了五参数的求解方法,给出了不同温度及辐照情况下的性能变化方程。提供了较为准确的赋初值方法,并给出了系统电模型及热模型的程序设计流程及相关实现步骤。对传统菲涅尔高倍发电阵列系统的光伏设计及相关散热翅片进行了介绍,在此基础上提出了菲涅尔水冷散热高倍聚光发电供热系统。对菲涅尔聚光发电系统的水冷模块进行了试制,并将其取代常规的散热翅片,形成菲涅尔水冷聚光模块,同时搭建了系统实验测试平台。对比了基于水冷模块的菲涅尔HCPV/T与基于铝制翅片风冷型的HCPV模组的性能。菲涅尔HCPV/T系统的瞬态热效率为49.3%,电效率为26.5%,系统的综合效率将高达75.8%。在整个实验测试期间HCPV/T模组的平均热效率可达46.8%。为了更深入地研究菲涅尔HCPV/T系统的光电转换、光热转换及光电光热复合利用的性能,将所测实验数据与理论模拟进行对比分析,同时对系统光伏电池光电转化效率的温度系数、不同进口水温下的系统性能进行了理论研究。更多还原

【Abstract】 As one of the substitutes of traditional fossil energy, solar energy is clean, renewable and widely used. Photovoltaic technology, one of the important utilization patterns of solar energy, is worldwidely concerned. Concentrating photovoltaic technology uses the concentrator to improve surface energy density of PV module and reduce the necessary area of expensive photovoltaic cells. Therefore, it is an effective way to improve system efficiency and reduce system costs.Concerning the problem of uneven distribution of energy flux density in concentrating photovoltaic system and overtemperature of PV module, aiming to improve solar energy utilization efficiency and reduce system costs, this paper proposes a high concentration photovoltaic/thermal system, meanwhile designs and studies two high concentration photovoltaic/thermal systems (HCPV/T) of reflection and refraction with forced cooling device, by combining solar photovoltaic technology and photovoltaic/thermal technology. The systems collect waste heat besides electrical output, which improves photovoltaic efficiency and gains additional heat to improve overall efficiency of the system greatly. For the two HCPV/T systems, this paper establishes corresponding dynamic mathematical models and experimental test rigs, conducts intensive study on output characteristic of the photovoltaic cells, uniformity of energy flux density distribution and coupling relationship of photovoltaic and thermal features of the system under different concentration ratio, mass flow rate and other environment parameters by combining numerical simulation and experimental study.The main contents of this paper include the following aspects:Firstly, this paper establishes optical model of parabolic high-concentration concentrator, theoretically designs the focal length and area of the concentrator, according to optical theories such as concentration and solar image. To solve the problem of uniformity, this paper proposes multi-disc focal concentrator of high concentration ratio using a modular approach, and proposes the concentrating mode of replacing the continuous surface with plane mirror array. According to corresponding theoretical analysis, this paper builds a parabolic concentration system and a plane mirror array concentration system, and experimentally studied the energy flux density distribution. The result shows that the plane mirror concentration system fundamentally solves the problem of uniformity, and the system components are easily installed, low-cost, stable and of good wind resistance, while its concentration ratio is adjustable and the system can be applied to concentrating photovoltaic system of various concentration ratio.Secondly, combining high concentration ratio concentrator with plane mirror array and CPV/T module, this paper establishes a dynamic mathematical model and studies the design of the cells, the substrate and the heat exchanger under high energy flux. Moreover, this paper theoretically simulates temperature distribution of PV substrate, the heat exchanger and the cooling water along the flow direction, and calculates system thermal efficiency, electrical efficiency and overall efficiency. Additionally, this paper designs and studies a dual-axis tracking system according to photosensitive tracking and mechanical tracking program.Thirdly, this paper builds a HCPV/T system of plane mirror array, tests and calculates key temperature parameters, thermal efficiency, electrical efficiency, and overall efficiency of the system, while deeply analyses the influence of different concentration ratios, mass flow rates and environment parameters on the thermal and electrical efficiency of the system. Experimental results show that the HCPV/T system has good thermal and electrical performance, with electrical efficiency of22%, thermal efficiency of47%, and overall efficiency of about70%. Also, this paper experimentally and theoretically studies temperature coefficient of CPV/T module’s electrical output.Fourthly, this paper proposes a Fresnel HCPV/T system of water cooling device, and theoretically studies the system, analyses design and optical performance of the Fresnel prism. Dynamic model of the Fresnel cooling system is established, including system thermal model and electrical model. This paper also establishes the single diode five parameter model under standard conditions, discusses the solving method of five parameters, and gives the performance change equation at different temperatures and different irradiation conditions, while providing relatively accurate initial value method, and giving the program process of the thermal and electrical model of the system.Fifthly, this paper introduces traditional high concentration system with Fresnel array and related cooling fins, and proposes Fresnel HCPV/T system of water cooling module. Water cooling module of the Fresnel HCPV/T system is produced and replaces traditional cooling fins to form Fresnel water cooling module, and a test rig based on it is built. The experiment compares the performance of the Fresnel HCPV/T system with water cooling device and HCPV module based on air-cooled aluminum fins. Transient thermal efficiency of the Fresnel HCPV/T system can reach49.3%, electrical efficiency is26.5%, and overall efficiency of the system can be up to75.8%. The average thermal efficiency of the HCPV/T module can reach46.8%throughout the experiment. To intensively study thermal efficiency, electrical efficiency, and overall efficiency of the HCPV/T system, the experimental data and the simulation results are compared, while temperature coefficient of electrical efficiency of the system, performance under different inlet water temperature are studied.更多还原