一种槽式太阳能空气集热器热性能的试验研究

为了研究日光温室用槽式太阳能空气集热器的热性能,基于TracePro光学模拟软件设计了一种槽式太阳能空气集热器,对其进行试验研究,分析了不同因素对集热性能的影响规律。实验结果表明,管中空气流速的变化对集热器集热效率和集热量的影响规律是相同的,在不同的流速下,存在最佳空气流速约为4.4 m/s,使得集热器的集热量和集热效率最大,集热量达到373.2 W,集热效率约为25%,此时集热性能最好。对于不同太阳辐照度,正午时刻之前,太阳辐照度越大,集热器的集热效率越大,正午时刻之后,集热器的集热效率基本保持不变,15:40之后集热器集热效率逐渐减小。当太阳辐照度和管中流速相同时,室外温度越高,集热器集热效率越大,集热性能越好。集热管中空气温度沿着集热管出口方向不断增大,太阳辐照度越大,集热管相同位置空气温度越高。该研究结果可为此种槽式太阳能空气集热器在日光温室的应用中提供参考。     

非对流层数对太阳池性能的影响

盐梯度太阳池是一种兼具集热与蓄热功能的太阳能利用设施。在太阳池的工程应用中,非对流层(NCZ)层数对太阳池性能影响问题十分重要,然而以往对这方面的研究较少。文章通过构建小型太阳池,设置不同的NCZ层数,分析其对太阳能集热和储热性能的影响。研究结果显示:随着NCZ层数增加,太阳池集热性能减弱;无NCZ太阳池平均每小时的集热量分别是含有1,2,3层NCZ太阳池集热量的1.11倍、2.52倍和4.03倍,热效率分别是其1.39倍、2.86倍和5.21倍;NCZ层数增加,夜间散热量减小,无NCZ太阳池中,夜间平均散热量是含3层NCZ太阳池散热量的3.56倍。在构建太阳池时,应充分考虑当地的气候条件和实际用途,设置适当的NCZ层数,方可发挥太阳池的最大功效,达到最大经济效益。     

盐梯度太阳池双扩散模型及热盐变化规律数值模拟

建立盐梯度太阳池热盐扩散二维简化数学模型,对1.0 m×1.5 m的太阳池进行数值分析,得出太阳池蓄热过程中的热盐瞬时扩散规律,并与实验值相比较,两者吻合较好。研究结果表明:随着太阳辐射时间的增加,上对流层和下对流层的对流微团数逐渐增多,使得非对流层厚度减小而上下对流层厚度均增加,但在一定时间内盐度梯度造成的密度梯度始终大于温度梯度引起的密度梯度,从而抑制非对流层的对流产生,为实际盐梯度太阳池的运行与维护提供参考依据。     

纳米颗粒对盐梯度太阳池热性能影响的实验研究

为了增强太阳池的储热温度以及热效率,采用了在太阳池下对流层添加纳米颗粒的方法.通过光照实验与沉降实验选取质量分数为0.010％的碳纳米管溶液添加到太阳池的下对流层,然后与普通盐梯度太阳池进行对比实验,并对实验数据进行分析、计算.实验结果表明:在相同模拟光源下,含纳米颗粒小型太阳池的下对流层平均温度提高了 1.7℃,效率...     

遮阳板式太阳能相变集热器的实验研究

研制了遮阳板与集热器一体化的新型太阳能相变集热器,通过搭建的实验测试平台对其集热性能及隔热特性进行了实验测试。该建筑构件具备遮阳隔热及太阳能集热功能,为在建筑中高效利用太阳能,实现太阳能与建筑一体化提供一种新的工程应用模式。通过实验测试,对该集热器在不同工况下的集热性能、隔热特性及其影响因素进行了系统分析研究,提出了该集热器的累积集热量、集热效率、隔热特性等性能评价指标。测试结果表明,遮阳板式太阳能相变集热器的平均集热效率可达12.3%,隔热效果优于普通遮阳板。     

太阳能平板集热/储热系统

介绍一种将相变储热材料和太阳平板空气集热器相结合的太阳能集热/储热系统(包括结构设计和试验测试),并对整个系统的储热效率和热损失进行了估算.结果显示,装置的储热效率可达23%,热效率达55%.而同样情况下的普通集热器的热效率仅为19%,远远小于前者.因此,该太阳能集热/储热系统可有效降低集热器的热损失,提高集热效率.     

铝幕墙板太阳能集热器的性能研究

研制了一种铝幕墙板与集热元件一体化的新型太阳能集热器,并通过所搭建的测试平台对其集热性能及隔热特性进行了测试研究。通过实验测试,对该集热器在不同工况下的集热性能、隔热特性及其影响因素进行了系统分析,得出了集热器的累积集热量、集热效率、隔热特性等性能评价参数。测试结果表明,铝幕墙板太阳能集热器的平均集热效率为23%,隔热性能优于普通铝幕墙板。该装置具有太阳能集热及隔热功能,为建筑高效利用太阳能,实现太阳能与建筑一体化提供了一种新的工程应用模式。     

多孔介质对太阳池传热传质影响的研究

通过实验与数值模拟相结合的方法研究在太阳池底部增设多孔介质水层对太阳池热盐双扩散及储热量、稳定性等的影响.在实验室研究了多孔介质对盐扩散的抑制作用.在海边沙滩建造了两个小型太阳池,测量了有无多孔介质太阳池的温度分布和盐度分布并进行数值模拟,模拟值与实验值吻合较好.计算了有无多孔介质太阳池盐梯度的分布、池子稳定性情况以及多孔介质对太阳池的储热量的影响.结果表明,在太阳池底部加设多孔介质水层可以提高太阳池LCZ温度.多孔介质水层有利于提高太阳池的储热量,有利于抑制盐分向上扩散,可以节省太阳池的盐资源消耗,并有利于提高非对流层的盐梯度和稳定性.     

太阳能空气集热器(Ⅰ型)的数学模型研究

用数学模型化方法研究了太阳能空气集热器的集热传热性能,建立了基于二维假设下的流体流动和热量传递的稳定态数学模型,并用有限差分法进行数值求解,计算得到稳态下太阳能空气集热器的速度、温度分布图以及集热效率与空气流量、入口空气温度、入身太阳辐照度和表面盖板透过率的关系。结果表明,对Ｉ型太阳能空气集热器,集热效率随空气流量和表面盖板透过率的增加而增大,随入口空气温度和入射太阳辐照度的增大而减小。计算结果与     

不同非对流层盐梯度层层数对太阳池性能影响

研究不同非对流层层数对太阳池稳定性、热性能的影响,以实现太阳池性能的优化。以工业NaCl为工质配制不同盐度溶液制备太阳池。以浊度、盐度和温度为考核指标,对太阳池的稳定性、吸热性和储热性进行研究。结果表明:当上对流层、非对流层、下对流层所占太阳池池体体积比率不变,非对流层各层厚度均匀设置时,太阳池降浊速度、盐梯度层稳定性、热性能均随太阳池非对流层盐梯度层层数的增加而增加。增加非对流层盐梯度层层数有利于改善太阳池的性能,太阳池的最佳非对流层盐梯度层层数为4。     

Investigating different diffuse solar radiation models to analyse solar radiation on inclined surfaces in Oman

In this paper, a detailed analysis of the solar radiation on horizontal and tilted surfaces for six locations in Oman is presented. The locations are (from North to South): Majis/Sohar, Sur, Fahud, Masira, Marmul, and Salalah. These locations spread over Oman and cover different types of landscape. The method is validated through the use of measured data. The effect of tilt angle and orientation on the incident solar radiation is presented along with optimum surface tilt angles and directions for maximum solar radiation collection in these six locations. The solar radiation models used in this paper show good agreement with measured data. The results presented in this paper are extremely useful for quick estimation of solar radiation for calculations of buildings’ cooling load and solar collector system performance. This can be easily extended for other locations with similar landscapes and geographical conditions.     

多孔太阳墙式太阳能房间与普通房间热舒适性分析

通过对某多孔太阳墙式太阳能房间和普通房间的数值模拟,分析太阳墙板内空气的受热过程及流动情况,同时系统地比较两种建筑在工作区范围内的热舒适性。与普通采暖房间相比,在有多孔太阳墙送风的情况下,可将室外空气由-3℃加热到21℃,空气流动速度由0.1m/s提高到0.31m/s,提供44.6m3/h的新风量,一定程度上解决了冬季开窗换气所引起的室内热负荷及采暖负荷,论证了多孔太阳墙可使室内热舒适性明显增强的结论。     

太阳时角对槽式聚光器焦线位置的影响

在讨论太阳时角对槽式聚光器焦线位置影响的基础上,建立了因焦线运动导致太阳辐射损失的理论模型.通过对昆明晴天不同节气下的焦线运动和太阳辐射损失的分析和计算,得到了焦线随时角变化的一般规律以及瞬时太阳辐射强度损失和不同时段的太阳辐射相对损失率,并与实验进行了对比.针对焦线运动的特点,提出了对槽式集热系统接收器的改进措施和建议,认为对于大规模的槽式聚光集热器利用,因焦线运动造成的太阳辐射损失可不必考虑.     

Experimental study of a refrigerant charged solar collector

The performance of a heat-pipe solar collector was investigated experimentally using refrigerants R11 as the working fluid. The unit is fabricated locally and its performance is evaluated under Beirut Solar conditions. The heat transfer from the heat pipes to the hot-water storage tank took place through a circular end condenser section of the heat-pipe integrated within the collector frame. Tests of single heat pipes showed that the thermal performance of the heat pipe were dependent on its tilt angle, condenser section length and configuration, and type of internal wick used. A circular condenser end of the heat-pipe performed better than a straight condenser due to increased surface area for heat transfer. The R11-charged solar collector with integrated condenser for secondary cooling of water had an efficiency in early operation hours that reached values higher than 60% for the forced circulation mode. The instantaneous system efficiencies varied from 60 to 20%, which are in the range of conventional water solar collectors. System response was fast and sensitive to the incident solar radiation. The thermosyphonic mode of the system operation generated build up of stored energy in the condenser, resulting in oscillating-type flow thus reducing system efficiency below values obtained with forced circulation. © 1998 John Wiley & Sons, Ltd.     

家用太阳热水器与太阳热水系统的技术经济比较

分析了户用太阳热水器和太阳热水系统工程的经济技术特点,对两者成本构成、项目财务净现值、投入回收期和财务内部收益率等有关指标进行了经济技术比较.分析比较表明,太阳热水系统与家用热水器相比,节省安装占地,与建筑相结合得好,在降低成本,缩短投资回收期,提高经济效益方面有明显的优势.     

Enhancement of the yield of solar still with the use of solar pond: A review

A solar pond (SP) is a remarkable growth of renewable energy technology that has stored solar energy for storage purposes and is used in many solar thermal applications. It is also utilized for many purposes, such as heating, cooling, space heating, air conditioning, and many more. The present paper shows the use of an SP to improve the yield of solar still (SS) by providing hot water through the heat energy stored in it. It also reveals the use of shallow and mini SPs with SS to improve yield. Various future research works on SS using SPs have also been included in this paper. From the current review paper, it was concluded that the SP increases the yield of the SS.     

Performance analysis of a solar cooker in Turkey

A box‐type solar cooker is designed and its thermal performance is analysed experimentally. The cooker tracks the sun in two axes, altitude and sun azimuth, by hand control for hourly periods. The experimental results show that the tested cooker may be assumed suitable in some cooking processes for specific country conditions. Copyright © 2002 John Wiley & Sons, Ltd.     

Mapping of solar energy potential and solar system capacity in Iran

Studies of the DLR Mediterranean – Concentrated Solar Project indicate Iran can be a part of the Mediterranean renewable power generation chain in 2050 to provide the electrical power demand of Europe. However, Iran as a developing country and due to its large area has some limitations on the number of synoptic stations. Hence, the aim of this study is to determine the theoretical solar irradiation potential in Iran by using an Niroo Research Institute irradiation model based on the geographical and meteorological data. Monthly, seasonal, and annual values of irradiation on the ground surface, and extracted solar energy from different tracking systems, are estimated across the country. A typical photovoltaic system, parabolic trough, and dish concentrator are considered and extracted solar energy of them is illustrated on the map. Results of this study make clear that the presented solar atlas can provide appropriate tools for primary study of solar energy potential and extracted energy in Iran.     

Development of an embedded solar tracker for the enhancement of solar energy utilization

An embedded two‐axis solar tracking system using Laboratory Virtual Instrumentation Engineering Workbench to write the operation and control algorithms was developed for enhancing solar energy utilization. The system consists of a real‐time processor, two motion‐control modules, two step drives, two step motors, feedback devices, and other accessories needed for functional stability. The real‐time processor allows the solar tracker to be used as a stand‐alone, real‐time system that can operate automatically without any external control. The system combines two different solar tracking methods: the optical method and the astronomical method. Cadmium Sulfide (CdS) sensors are employed to continuously generate feedback signals to the controller, ensuring high‐precision solar tracking even under adverse conditions. The CdS sensor is a resistor whose electric resistance decreases with increasing incident light intensity. A database of solar altitude, azimuth, and sunrise and sunset times is provided by this solar tracking system. Other solar trackers operating in an astronomical method may access and use this database over the Internet. Solar position and sunrise and sunset times in the database were compared with those of the Astronomical Applications Department of the U.S. Naval Observatory. The differences were found to be negligible. Copyright © 2011 John Wiley & Sons, Ltd.     

太阳能电池研究的新进展

简要回顾了第一代晶体硅和第二代薄膜太阳能电池的发展状况,并介绍了基于薄膜技术的第三代高性能太阳能电池的基本原理和发展趋势。