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。     

聚光热发电技术的分析和简评

基于传热学、工程热力学的基本原理,结合实际应用,对槽式、塔式、碟式、分立式4种太阳能聚光热发电技术的特点、局限性、发展潜力进行初步分析。槽式技术是最成熟的聚光热发电技术,但是受聚光集热特性的影响,提高发电效率的难度较大;建议塔式技术优化跟踪聚光技术,以提高聚光效率,同时选择合适的单塔功率;为了充分发挥碟式技术的高温潜力,需要开发超高温热机;分立式技术提高了聚光效率,简化跟踪系统,但聚光采用的高次曲面镜价格昂贵。建议聚光技术可直接将高温工艺热应用于终端,提高热利用效率;远期可考虑高温热解制氢,利用氢气便于储存的优势,克服太阳能不稳定的先天缺陷。     

光热发电产业发展现状及成本展望

综述光热发电技术类型,介绍塔式、槽式、线性菲涅尔式和碟式几种聚光集热方式的技术路线及显热储热和相变储热2种储热方式。针对国内外光热发电项目发展状况,分析光热发电成本构成,总结国际上不同机构对光热发电成本的研究成果。     

对我国发展太阳能热发电的一点看法

太阳能热发电是大规模开发利用太阳能的一个重要技术途径。由于关键技术有待重大突破,目前国外塔式、槽式、碟式系统都还面临着投资大、成本高的问题。本文分析了塔式、槽式、碟式现行三种技术路线在我国推广应用的技术难点,提出了一个新型分立式太阳能热发电技术路线。这项新技术建立在太阳聚光跟踪理论突破的基础之上,不仅具有完全自主知识产权,而且比国外现行的热发电技术更为经济高效。     

塔式太阳能热发电技术的发展

塔式太阳能热发电系统具有聚光比大、投射到塔顶吸热器上的平均热流密度高、工作温度高、电站规模大和年度发电效率高等特点,提高效率和降低成本的潜力较大。文章阐述了塔式太阳能热发电技术的工作原理和系统组成;介绍和分析了国内外已建成的塔式太阳能电站;指出了塔式太阳能热发电技术的发展现状、技术难点和未来发展方向;探讨了我国规模化发展塔式太阳能热发电技术须解决的问题。     

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。     

太阳能光热发电技术发展现状

介绍太阳能光热发电技术系统：塔式、槽式和碟式3种太阳能光热发电系统,对各类太阳能光热发电技术与常规发电技术进行分析对比,阐述3种太阳能光热发电技术的发展现状及其存在的问题,说明太阳能光热发电具有的广阔应用前景。     

我国太阳能热发电产业现状与展望

太阳能热发电是支撑我国国民经济可持续发展的前瞻性、战略性的新能源产业,《可再生能源"十三五"规划》提出到2020年太阳能热发电装机规模达到500×104k W。目前我国聚光型太阳能热发电还处于示范推广的初级阶段,面临的主要问题是发电成本高以及高聚光比、高性能吸收涂层、高温蓄热等关键技术有待突破。提高太阳能热发电效率、增加年净发电量、提高电站设备国产化率、降低电站初期投资费用是降低太阳能热发电成本的重要途径。2016年国家确定首批20个太阳能热发电示范项目,希望通过示范项目建设,对不同技术路线进行全面比较,带动产业发展,提高技术水平,降低发电成本。国家出台太阳能热发电标杆上网电价等一系列政策,并参与国际行业标准制定,这些都为我国太阳能热发电产业提供了重大发展机遇。低成本、大容量、连续发电,是聚光型太阳能热发电未来的研究和发展方向,要在提高聚光比、提高运行温度方面实现突破,加大太阳能热电转换等核心技术和关键设备的研发力度,加强基于多能互补的联合循环发电技术以及太阳能热发电对电力系统作用的研究。     

基于DAC概念的改进型聚光电热联用系统

基于DAC技术对传统的聚光电热联用系统(CPV/T)进行优化设计,采用水为吸热工质与常规硅太阳电池相结合对太阳能辐射进行分波段利用,分别完成光热转换和光电转换。对该改进CPV/T系统建立了辐射传递模型和能量平衡模型:首先,对太阳能辐射在系统中的传递过程进行了分析;而后对系统的光热单元和光电单元工作温度进行了计算。计算结果显示该系统光热单元温度不再受光电单元工作温度限制,随着聚光比的增加该系统光热单元可产出高温热能,其吸热工质出口温度可达到108℃,而相应的光电单元工作温度低于69℃,同时通过试验对系统光电性能进行了对比分析;最后对该CPV/T系统效率进行分析,得到其光热转换效率为32%,光电转换效率保持在8.6%～10.5%之间。     

太阳能雾化闪蒸DSG热发电的试验研究

一引言在槽式太阳能热发电系统中,采用DSG(direct steam generation)即直接蒸汽发电技术,可替代昂贵的传热流体导热油,显著降低制造成本,提高光热转换效率,但压力波动等技术障碍阻碍了DSG技术的应用。至今在太阳能热发电领域,还没有采用DSG技术的抛物槽式电站。目前,太阳能热发电期待突破的科技前沿主要是降低成本、替代合成导热油和热交换器、提高热力学效率三项课题。一些科研人员正以DSG技术为突破口,提高太阳能热发电的竞争力,从而实现太阳能热发     

Thermodynamic performance study of the MR SOFC-HAT-CCHP system

Based on Aspen Plus, a methanol reforming Solid Oxide Fuel Cell - Humid Air Turbine - Combined cooling, heating and power (SOFC-HAT-CCHP) system based on solar methanol reforming is built in this paper, which combines (Solid Oxide Fuel Cell) SOFC with (Humid Air Turbine) HAT power generation system. This paper analyzes the performance of SOFC-HAT-CCHP system, and reveals the affinity of complementary utilization of solar energy and chemical energy. This paper optimizes the integrated design of the system and constructs a steady state model of the system's thermal calculation. The calculation results show that the total power efficiency of the method, the system total exergy efficiency and the thermal efficiency are 57.2%, 63.0% and 87.1% respectively. The results show that the introduction of HAT power generation system has increased the power generation and reduced the coal consumption rate. Compared with simple methanol reforming (Solid Oxide Fuel Cell - Gas Turbine - Combined cooling, heating and power) SOFC-GT-CCHP, the introduction of HAT effectively improves the total power generation efficiency of the system and increases 4.1% points. The exergy efficiency of increased by 4.6% points. Compared to the reference system, the standard coal consumption rate of electricity generated by the new system decreased by 16.6 g/kWh and the power generation increased by 15.5 g/kWh.     

A new hybrid ocean thermal energy conversion–Offshore solar pond (OTEC–OSP) design: A cost optimization approach

Solar thermal electricity (STE) generation offers an excellent opportunity to supply electricity with a non-CO₂ emitting technology. However, present costs hamper widespread deployment and therefore research and development efforts are concentrated on accelerated cost reductions and efficiency improvements. Many focus on the latter, but in this paper we rather focus on attaining very low levelised electricity costs (LEC) by designing a system with very low material cost, while maintaining appreciable conversion efficiency and achieving low maintenance cost. All investigated designs were dimensioned at a 50 MW scale production. Calculated LECs show that a new proposed hybrid of ocean thermal energy conversion with an offshore solar pond (OTEC–OSP) may have the lowest LEC of 0.04 €/kWh. Addition of a floating offshore solar pond (OSP) to an OTEC system increases the temperature difference in the Rankine cycle, which leads to an improved efficiency of 12%, while typical OTEC efficiencies are 3%. This higher efficiency leads to much lower investments needed for power blocks, while the OSP is fabricated using very low-cost plastic foils. The new OTEC–OSP design can be located in many sunny coastal areas in the world.     

不同装机容量下S-CO2塔式太阳能热发电系统的热力及经济性能分析

建立超临界CO₂布雷顿循环塔式太阳能热发电系统的热力性能和经济性能模型,比较不同装机容量下系统的年均效率,分析系统中各项成本占比及其随容量增长的变化规律,提出进一步降低发电成本的方法。结果表明,主要受镜场效率的影响,系统年均效率随装机容量增加先升后降,峰值为20 MW时的17.4%。发电成本随装机容量的增加而减小,由1 MW时的0.477 美元/kWh降至100 MW时的0.125 美元/kWh。减小镜场和储热的投资成本是降低大规模电站发电成本的关键。     

A parabolic dish/AMTEC solar thermal power system and its performance evaluation

This paper proposes a parabolic dish/AMTEC solar thermal power system and evaluates its overall thermal–electric conversion performance. The system is a combined system in which a parabolic dish solar collector is cascaded with an alkali metal thermal to electric converter (AMTEC) through a coupling heat exchanger. A separate type heat-pipe receiver is selected to isothermally transfer the solar energy from the collector to the AMTEC. To assess the system’s overall thermal–electric conversion performance, a theoretical analysis has been undertaken in conjunction with a parametric investigation by varying relevant parameters, i.e., the average operating temperature and performance parameters associate with the dish collector and the AMTEC. Results show that the overall conversion efficiency of parabolic dish/AMTEC system could reach up to 20.6% with a power output of 18.54 kW corresponding to an operating temperature of 1280 K. Moreover, it is found that the optimal condenser temperature, corresponding to the maximum overall efficiency, is around 600 K. This study indicates that the parabolic dish/AMTEC solar power system exhibits a great potential and competitiveness over other solar dish/engine systems, and the proposed system is a viable solar thermal power system.     

Comparative energy,exergy and exergo-economic analysis of solar driven supercritical carbon dioxide power and hydrogen generation cycle

Parabolic dish solar collector system has capability to gain higher efficiency by converting solar radiations to thermal heat due to its higher concentration ratio. This paper examines the exergo-economic analysis, net work and hydrogen production rate by integrating the parabolic dish solar collector with two high temperature supercritical carbon dioxide (s-CO₂) recompression Brayton cycles. Pressurized water (H₂O) is used as a working fluid in the solar collector loop. The various input parameters (direct normal irradiance, ambient temperature, inlet temperature, turbine inlet temperature and minimum cycle temperature) are varied to analyze the effect on net power output, hydrogen production rate, integrated system energetic and exergetic efficiencies. The simulations has been carried out using engineering equation solver (EES). The outputs demonstrate that the net power output of the integrated reheat recompression s-CO₂ Brayton system is 3177 kW, whereas, without reheat integrated system has almost 1800 kW net work output. The overall energetic and exergetic efficiencies of former system is 30.37% and 32.7%, respectively and almost 11.6% higher than the later system. The hydrogen production rate of the solarized reheat and without reheat integrated systems is 0.0125 g/sec and 0.007 g/sec, accordingly and it increases with rise in direct normal irradiance and ambient temperature. The receiver has the highest exergy destruction rate (nearly 44%) among the system components. The levelized electricity cost (LEC) of 0.2831 $/kWh with payback period of 9.5 years has proved the economic feasibility of the system design. The increase in plant life from 10 to 32 years with 8% interest rate will decrease the LEC from (0.434-0.266) $/kWh. Recuperators have more potential for improvement and their cost rate of exergy is higher as compared to the other components.     

Prospectives for China's solar thermal power technology development

China's total installed electrical power capacity reached 700 GW by the end of 2007 and is predicted to surpass 900 GW in 2010. The rapid increase in energy demand and increasing global warming have both pushed China to change its current electrical power structure where coal power accounts for nearly 75% of the total electric power generation. China has already become the world's largest solar water heater producer and user. However, there is still much to be done in the solar thermal power field before its commercialization. Solar thermal power technologies including solar power towers, solar parabolic trough concentrators, solar dish/stirling systems, linear Fresnel reflectors, and solar chimneys have been studied in China since the 1980s. A 10 kW dish/stirling project was funded by the Ministry of Science and Technology (MOST) during 2000–2005 with a 1 MW solar power tower and research of trough concentrator metal–glass evacuated tubes supported during 2006–2010. This paper describes a continued solar thermal power development roadmap in China in 5-year intervals between 2006 and 2025.     

Optical fibers and solar power generation

A study of the potential use of optical fibers for solar thermal power generation is presented. The main performance characteristics (numerical aperture and attenuation) and typical costs of currently available fibers are discussed. Several approaches to the application of fibers are presented, for centralized (tower, central receiver) and distributed (dish–engine) systems. The overall system design-point efficiency and overall system cost are estimated. A scaling relation between system size and the cost of the fiber component is identified, which severely limits the applicability of fibers to small systems only. The overall system cost for centralized systems is found to be higher than the currently competitive range, even under optimistic assumptions of mass production of major components. A significant reduction in fiber cost is required before the use of fibers for centralized solar power generation can become competitive. In distributed generation using dish/engine systems, however, the use of fibers does achieve competitive performance and costs, comparable to the costs for conventional dish systems.     

Parametric analysis for the installation of solar dish technologies in Mediterranean regions

In this work a feasibility study is carried out in order to investigate whether the installation of solar dish technologies for power generation in Mediterranean regions is economically feasible. The study takes into account the available solar potential for a typical Mediterranean country, such as Cyprus, as well as all available data concerning the current renewable energy sources policy of the island, including the relevant feed-in tariff of 0.26€/kWh. In order to identify the least cost feasible option for the installation of the solar dish plant a parametric cost–benefit analysis is carried out by varying the solar dish plant capacity, the solar dish plant capital investment and the CO₂ emissions trading scheme price. The results indicated that the installation of solar dish plants in Mediterranean regions is economically feasible only in some cases, when a feed-in tariff incentive scheme exists, and that the size and the capital cost of the solar dish power plant are critical parameters affecting the economic viability of the technology.     

聚光太阳能发电技术应用与前景

分析了聚光太阳能发电三大技术（线性聚光系统、碟/引擎系统、电力塔系统）以及热能储存系统,阐述了其结构、工作原理与研究方向,比较了这三大技术之间的经济技术性能,介绍了适合我国太阳能辐射量大的边远地区碟/引擎系统的应用,展示了太阳能热发电技术的应用前景及对节能减排的贡献。     

Energy and exergy analyses on a novel hybrid solar heating,cooling and power generation system for remote areas

In this study, a small scale hybrid solar heating, chilling and power generation system, including parabolic trough solar collector with cavity receiver, a helical screw expander and silica gel–water adsorption chiller, etc., was proposed and extensively investigated. The system has the merits of effecting the power generation cycle at lower temperature level with solar energy more efficiently and can provide both thermal energy and power for remote off-grid regions. A case study was carried out to evaluate an annual energy and exergy efficiency of the system under the climate of northwestern region of China. It is found that both the main energy and exergy loss take place at the parabolic trough collector, amount to 36.2% and 70.4%, respectively. Also found is that the studied system can have a higher solar energy conversion efficiency than the conventional solar thermal power generation system alone. The energy efficiency can be increased to 58.0% from 10.2%, and the exergy efficiency can be increased to 15.2% from 12.5%. Moreover, the economical analysis in terms of cost and payback period (PP) has been carried out. The study reveals that the proposed system the PP of the proposed system is about 18 years under present energy price conditions. The sensitivity analysis shows that if the interest rate decreases to 3% or energy price increase by 50%, PP will be less than 10 years.