利用太阳能集热器系统仿真模型对Cairo地区季节划分的仿真研究

提出了太阳能集热器系统单元（微元）段分节点热阻、热容网络－四维热网络概念，并依此建立了腔体式吸收器－槽形抛物镜太阳能集热器系统的集热过程动态仿真模型。根据地理位置和不同季节的气象条件，利用仿真模型和太阳直射辐射日分布模型，计算了埃及Ｃａｉｒｏ地区在几个典型月份的日均太阳直射辐射强度Ｉｂ、工质温度Ｔｆｍ、瞬时集热效率Ｐｔｏｔ，ｃ，ｎ和瞬时Ｙｏｎｇ效率Ｐｅ，ｃ，ｎ随时间的分布。     

以Yong效率优化太阳能集热器工作温度

依据槽形抛物镜－管簇结构腔体式吸收器太阳能集热器的热阻网络和建立的集热器Ｙｏｎｇ效率优化模型，在单一改变太阳直射辐照度及同时改变腔体窗光学性能情况下，分别计算了工作介质温度Ｔｆｍ，ｍ的最优运行取值。     

以效率优化太阳能集热器工作温度

依据槽形抛物镜－管簇结构腔体式吸收器太阳能集热器的热阻网络和建立的集热器效率优化模型，在单一改变太阳直射辐照度及同时改变腔体窗光学性能情况下，分别计算了工作介质温度Ｔｆｍ，ｍ的最优运行取值。     

利用四维热网络仿真模型计算反射镜和腔体窗光学性能对太阳能集热器系统热性能的影响

首次提出太阳能集热器系统单元（微元）段分节点热阻、热容网络——四维热网络概念，并以此建立腔体式吸收器－槽形抛物镜太阳能集热器系统的集热过程动态仿真模型。利用该模型计算了抛物镜反射率ｐ、腔体窗透过率ｔｇ及腔体窗发射率ｅｇ对太阳能集热器系统热性能的影响     

太阳能集热器系统的四维热网络动态仿真模型

在首次提出太阳能集热器系统单元（微元）段分节点热阻、热容网络－－四维热网络概念基础上,建立腔体式吸收器－槽形抛物镜太阳能集热器系统的集热过程动态仿真模型。在外界驱动力均变的情况下,该模型不但可求得集热器系统中任一切面各部件温度随时间的分布,也可求得任一时刻各部件温度沿集热器系统的空间分布,从而首次实现大型太能集热器运行工况的四维动态仿真。     

槽式太阳能聚焦集热器太阳跟踪方式的优化研究

通过数值模拟的方法为槽式太阳能聚焦集热器选取一种最佳的太阳跟踪方式,具体研究内容包括:地表日太阳直射辐射量的计算、不同太阳跟踪方式时槽式太阳能聚焦集热器的抛物面反射镜年接收太阳直射辐射总量的对比,以及南北倾斜式跟踪方式最佳倾角的研究.研究发现,在上海地区,槽式太阳能聚焦集热器的抛物面反射镜接收的太阳直射辐射量从高到低排...     

利用四维热网络仿真模型计算反射镜和腔体窗学性能对太阳能集热器系…

首次提出了太阳能集热器系统单元分节点热阻，热容网络－四维热风格概念，并以此建立腔体式吸收器－槽形抛物镜太阳能集热器的集热动态仿真模型。利用该模型计算了抛物镜反射率ｐ，腔体窗透过度ｔｇ及腔体窗发射率ｅｇ对太阳能集热器系统热性能的影响。     

不同气候条件下平板太阳能集热器动态热性能的解析

利用一种可结合环境气象数据等参数来计算平板太阳能集热器一段时间内集热效率动态分布的数学模型,对比研究了不同气候区典型城市年平均效率及逐月效率分布的差异,分析了入口温度与环境温度温差、太阳辐照度对集热器全年瞬时效率的影响,并将该模型与《太阳能供热采暖工程技术规范》中的集热效率计算方法进行了对比。通过分析说明了在研究太阳能集热器的集热效率时,应结合气象条件和运行参数动态进行研究分析,冬季的瞬时效率并非总是低于夏季。该模型可更精确地模拟实际工程情况来计算集热器平均效率,是一种更加适应不同气候地区的太阳能集热器热性能模型,为工程实例中平板太阳能集热器平均效率的选取提供了参考。     

U型管式真空管集热器的仿真及集热瞬态效率的计算

根据U型管太阳能集热器的内部结构的换热特点推导了U型管式太阳集热器的瞬时效率公式,建立了U型管太阳能集热器的能量平衡和等效肋片模型两种传热模型,通过数值计算在不同的环境温度、铝翼的平均温度和不同的太阳辐照强度下计算出U型管集热器的瞬态效率,并利用最小二乘法分别拟合出真空管的瞬态效率公式。与实测结果相比,两种方法均与试验数据基本吻合,其中能量平衡模型的归纳式误差更小一些。     

太阳集热器透明盖板透过率的计算

太阳光线由空气进入太阳集热器透明盖板时,存在折射现象。设空气的折射率为１,太阳光线入射角为θ１,折射角为θ２,透明盖板材料的折射率为ξ,根据光的折射定律,入射角θ１、折射角θ２与盖板材料的折射率ξ之间存在着下列关系：ξ＝ｓｉｎθ１ｓｉｎθ２（１）对于北半球,面向正南安装的集热器,其方位角γｎ＝０°,则太阳光线入射角θ１可用下式计算：ｃｏｓθ１＝ｓｉｎ（φ－ｓ）ｓｉｎδ＋ｃｏｓ（φ－ｓ）ｃｏｓδｃｏｓω（２）式中：φ———地理纬度;ｓ———集热器倾角;γｎ———集热器方位角;δ———太阳赤纬;ω—…     

一种基于新结构的线性腔式太阳能集热器研究

提出一种适用于槽式太阳能热发电系统的新型线性腔式集热器。通过Tracepro模拟聚光镜焦距、弧形结构及开口宽度对系统光学性能的影响;采用热网络模型对该集热器的传热性能进行参数化研究,确定优化的集热器结构为优弧型,开口宽度为70 mm,与其匹配的聚光镜焦距为2100 mm。研究结果表明,当太阳直射辐射强度为500 W/m2,集热温度为650 K时,系统光热转换效率达65.3%。与一类传统真空管集热器的对比表明,该新型线性腔式集热器的集热性能优于UVAC Cermet直通式真空管集热器。另外,该线性腔式集热器生产和维护成本明显低于真空管集热器,对于促进槽式太阳能热发电技术具有重要意义。     

太阳能光伏／光热集热器设计与性能研究

光伏／光热（PVT）集热器集光伏发电与太阳能低温热利用为一体,通过冷却太阳电池得到低温热量,一方面达到提高电池效率的目的,另一方面可同时回收利用产生的低温热量。PVT集热器可实现较高的综合效率,而且在输出相同的情况下比分离式的太阳电池板和普通太阳集热器占地面积更少,是一种具有前景的新型太阳能利用技术。本文介绍了PVT集热器的概念设计和对其性能的理论和实验研究结果。     

A mathematical model of thermal performance of a solar air heater with slats

A mathematical model for computing the thermal performance of a single pass flat-plate solar air collector is presented. Air channels were formed by providing metal slats running along the circulated air passage linking the absorber plate by the bottom one in an endeavor to enhance the thermal efficiency of the solar air collector. A mathematical model, therefore, is developed by which the influence of the addition of the metal slats on the efficiency of the solar collector is studied. A computer code that employs an iterative solution procedure is constructed to solve for the governing energy equations to estimate the mean temperatures of the collector. The effect of volume airflow rate, collector length, and spacing between the absorber and bottom plates on the thermal performance of the present solar air heater was investigated. Furthermore, a numerical comparison of the present design with the most common type of solar air heaters is conducted. The results of the comparison have indicated that better thermal performance was obtained by the modified system.     

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.     

Optimum outlet temperature of solar collector for maximum work output for an Otto air-standard cycle with ideal regeneration

The optimum solar collector outlet temperature for maximizing the work output for an Otto air-standard cycle with ideal regeneration is investigated. A mathematical model for the energy balance on the solar collector along with the useful work output and the thermal efficiency of the Otto air-standard cycle with ideal regeneration is developed. The optimum solar collector outlet temperature for maximum work output is determined. The effect of radiative and convective heat losses from the solar collector, on the optimum outlet temperature is presented. The results reveal that the highest solar collector outlet temperature and, therefore, greatest Otto cycle efficiency and work output can be attained with the lowest values of radiative and convective heat losses. Moreover, high cycle work output (as a fraction of absorbed solar energy) and high efficiency of an Otto heat engine with ideal regeneration, driven by a solar collector system, can be attained with low compression ratio.     

太阳能烟囱发电新技术

介绍了一种太阳能烟囱发电新技术。太阳光辐射透过太阳能集热棚，加热集热棚下面的地面，被加热的地面与集热棚内的空气进行热量交换，使其温度上升，被加热的空气上升并进入与集热棚中部相连的烟囱，在烟囱内上升气流推动涡轮发电机旋转、发电。整个太阳能烟囱发电技术的能量转化以及效率可以从三个部分来分析：通过集热棚太阳能转化为空气热能，通过烟囱将热能转化为动能，通过涡轮发电机将动能转化为电能。另外，总结了太阳能烟囱发电技术的优缺点，指出它是一种适合于我国西部地区的一种能源开发新途径。     

Advancement in solar photovoltaic/thermal (PV/T) hybrid collector technology

This article presents an overview on the research and development and application aspects for the hybrid photovoltaic/thermal (PV/T) collector systems. A major research and development work on the photovoltaic/thermal (PVT) hybrid technology has been done since last 30 years. Different types of solar thermal collector and new materials for PV cells have been developed for efficient solar energy utilization. The solar energy conversion into electricity and heat with a single device (called hybrid photovoltaic thermal (PV/T) collector) is a good advancement for future energy demand. This review presents the trend of research and development of technological advancement in photovoltaic thermal (PV/T) solar collectors and its useful applications like as solar heating, water desalination, solar greenhouse, solar still, photovoltaic-thermal solar heat pump/air-conditioning system, building integrated photovoltaic/thermal (BIPVT) and solar power co-generation.     

Thermal performance of a trapezoidal-shaped solar collector/energy store

A simple, low-cost solar water heater has been developed for operation in Mediterranean Europe or regions of similar latitude (40–45° north). It takes the form of a trapezoidal-shaped water store in direct contact with an inclined flat-plate solar collector assembly. This cross-section induces thermal stratification in the water store, and provides sufficient energy storage to meet typical daily hot-water demand. Its thermal performance is critically dependent on the waterside convective heat-transfer coefficient on the backward-reclining collector plate; previously evaluated by Cruz et al. (Cruz JMS, Hammond GP, Reis AJPS. Buoyancy-driven convective heat exchange in a trapezoidal-shaped solar collector/thermal store. In: Proc. of the 5th ASME/JSME Joint Thermal Engineering Conf., San Diego, CA (ASME, New York), 1999, 9 pp). In the current design, the absorber plate inclination to the horizontal was fixed at 45° (close to the local latitude) in order to yield maximum solar gain over a typical year. The energy saving provided by the solar collector/thermal store demonstrator largely depends on the amount of thermal stratification within the trapezoidal storage cavity. This was evaluated via both computation and measurements of the temperature field. A thermal network analysis model was then used to assess the energy-saving potential of the composite system. It indicated that a 30–70% reduction in daily load could be obtained in contrast to direct, electrical or gas, heating: the smaller saving occurred at times of greatest use or hot-water take-off.     

腔体式吸收器与真空管吸收器的热性能比较

本文分析了槽形抛物镜聚光集热器中管族结构和环套结构的腔体式吸收器以及真空吸收器的热物理特征,画出其热阻网络,建立太阳能一般性控制方程,并以此为依据对这三种吸收器的热性能进行了数值分析比较。