真空溅射镀膜全玻璃真空管集热管

北京市双木环境科学新技术开发公司最新开发投产了真空管蓄热式太阳能集热器专利产品。该太阳能集热器采用了热效率高的真空溅射镀膜全玻璃真空管集热管,不仅保持了高太阳辐射吸收率、真空绝热等性能,而且结合了热管传热技术和相变蓄热技术。它完全克服了现     

太阳能平板集热器关键参数对其热性能的影响

为了提升太阳能在建筑能源供给体系中的比重,形式多样的太阳能集热设备及其系统在建筑领域得到了广泛应用。基于机理分析法,建立了具有单层玻璃盖板的管板式太阳能平板集热器的稳态传热模型。并且针对集热管间距、集热管内径、工质入口温度和工质质量流量等关键参数对集热器集热效率的影响特性进行了数值模拟与分析。结果表明,建立的该稳态传热模型是可行的;此外,在其余参数值保持不变的情况下,减小集热管间距或增加集热管内径均可使集热器瞬时效率增大;增大工质入口温度会导致集热器瞬时效率下降;而增大工质质量流量会提升集热器瞬时效率。这些结论对于太阳能平板集热器在太阳能建筑一体化的实际应用中,具有一定的参考作用。     

太阳能真空集热管性能及质量评价方式的探讨

真空管太阳能热水器市场在我国近年来发展较快.我国的测试标准体系也在努力适应市场的发展并与有关的国际标准接规.但由于太阳能真空集热管本身非ISO或欧洲EN标准定义的集热器,因此真空管本身的热性能评价无法套用ISO标准.为此,我国采取了单独对真空管本身的热性能进行评价的方法,并制订了相应的标准.由于真空管太阳热水器内水的流动是由温差驱动的自然对流,内部换热情况非常复杂,国家标准评价好的真空管并不能对应是好的热水器.因此本文认为,参考ISO标准在真空管热水器的评价体系中,对真空管本身似可以不作单独的测量和评价,而将评价放在真空管热水器的热性能测量中一并进行,这样可以更好地反映出用户的需求.     

储热式真空管闷晒性能参数检测方法分析

1．引言 全玻璃储热式真空集热管由大口径玻璃外管和内管组成,内管外表面具有太阳选择性吸收涂层。与其他真空集热管相比,该真空集热管的容水量特别大,所以无需传统的集热水箱,真空管本身就可以作为储存热水的装置,只要几根真空管简单的串联就可以作为集热器,并可方便地实现全天的热水供应：该真空管保温效果比用传统的储水箱效果好得多。同时储热式真空管热水器的集热器结构紧凑,安装方便,应用在建筑上,比直插式热水器更容易与斜屋顶相结合。     

U型管式全玻璃真空管太阳集热器的热性能

在U型管式全玻璃真空管集热器能量平衡分析的基础上,推导了集热器热损系数、效率因子等性能参数计算公式,其理论计算结果与实验数据吻合良好。计算分析表明：真空管热损系数与吸热管温和环境温度之差是非线性关系,将两者的计算关系式按环境温度分段整理将使计算结果更接近实际;涂层发射比对集热器效率影响较大,降低涂层发射比是提高集热器效率的有效途径;采取适当的措施降低吸热管与肋片接触热阻后,采用U型管连接方式不会对热水系统集热器效率造成太大影响。     

浅述太阳能集热器的选型

结合某工程实例,对目前常用的平板型、玻璃真空管型及热管型等太阳能集热器的优缺点进行了介绍,并对各种太阳能集热器进行了综合评价,根据评价提出了设计中推荐选用水平大热管型集热器的建议。     

直通式真空管太阳能空气集热器的实验研究

研究了一种新型的直通式多根真空管空气集热器装置,包括直通式(两端开口)真空集热管和上下分集管。直通式真空管太阳能空气集热器安装在南墙的外面,室内空气进入集热器,加热后送回房间,实现了太阳能供暖,不需要风机或者水泵,简单可靠。搭建了试验台并测试了冬季供暖时的热性能。通过实验得出,该装置集热效率最高的点出现在14:00,集热效率为51%,其集热效率最低的点出现在16:00,集热效率为46%,全天的总效率为36.3%,具有较高的热效率。     

能源材料聚焦"玻璃王"

玻璃王,即高硼硅3.3玻管,是实现太阳能光热转换所需的全玻璃真空太阳集管制作的必备核心技术材料。目前世界上只有少数几个国家能够生产该产品。吸收率与发射率是衡量全玻璃真空太阳集热管产品质的两大关键性指标。清华大学研制的全玻璃真空管集热器和北京太阳能研究所研制的热管式真空管太阳能集热器代表了当前的国际前沿技术,号称世界太阳能产业分水岭的“三靶干涉膜技术”已应用于国内规模化生产。目前,国产全玻璃真空太阳集热管的吸收率能达到93%以上、发射率小于0.05%,处于行业前列,产品已远销欧美等几十个国家和地区。全玻璃真空太阳…     

真空管太阳能集热器水温对集热效率的影响

通过分析真空管集热器传热的数学模型,介绍了容积式集热器的传热特点。并且结合实验测试数据,对集热器内液体温度对集热效率的影响进行了分析。结果显示:实验温度范围内集热器的集热效率分为三个阶段,当集热器的温度由38.1℃升高到45.2℃时,集热器的效率下降明显;当集热器的温度由45.2℃升高到57.1℃时,集热器的效率变化不大,基本稳定;当集热器的温度大于62.8℃时,集热器效率又开始呈现明显的下降趋势。通过对数据进行四阶多项式拟合,最后得出了集热效率与集热器温度之间的数学关系。     

基于动态传热分析的平板型太阳能集热器设计软件开发

平板型太阳能集热器的热性能受到环境因素、运行条件和设计因素的共同影响。为提升太阳能热利用工程的应用效果,需要针对环境和运行条件,对平板型太阳能集热器进行优化设计。本研究通过分析平板型太阳能集热器内部以及与环境间导热、对流、热辐射等动态传热过程,建立了计算集热量、集热效率以及集热器瞬时效率曲线的平板型太阳能集热器三维动态传热模型与差分求解算法,开发了具有传热过程分析和运行性能预测的平板型太阳能集热器设计软件,提高了不同环境因素、设计因素以及运行参数影响下集热器热性能分析速度和准确度。     

Thermal performance analysis of the glass evacuated tube solar collector with U-tube

In this paper, based on the energy balance for the glass evacuated tube solar collector with U-tube, the thermal performance of the individual glass evacuated tube solar collector is investigated by analytical method. The solar collector considered in this study is a two-layered glass evacuated tube, and the absorber film is deposited in the outer surface of the absorber tube. The heat loss coefficient and heat efficiency factor are analyzed using one-dimensional analytical solution. And the influence of air layer between the absorber tube and the copper fin on the heat efficiency is also studied. The results show that the function relation of the heat loss coefficient of the glass evacuated tube solar collector with temperature difference between the absorbing coating surface and the ambient air is nonlinear. In the different ambient temperatures, the heat loss coefficient of the solar collector should be calculated by different expressions. The heat efficiency factor will be subject to influence of air layer between absorber tube and the copper fin. Specially, the influence is remarkable when the heat loss coefficient of the collector is large. When the synthetical conductance amounts to 5 W/m K, the solar collector efficiency decreases 10%, and the outlet fluid temperature decreases 16% compared with the case which the air thermal resistance is neglected. And the surface temperature of the absorbing coating increases 30 °C due to the effect of air thermal resistance. So the surface temperature of the absorbing coating is an important parameter to evaluate the thermal performance of the glass evacuated tube solar collector.     

Performance evaluation of evacuated tube solar domestic hot water systems in Hong Kong

Evacuated tube solar water heaters are increasingly in use in Hong Kong because of their good thermal efficiency and high water temperature achievable as compared to the flat-plate solar water heaters. But so far their thermal performance has not been systematically evaluated and therefore not well known to the users. This paper reports our experimental and numerical works on evaluating the performance of the two common types of evacuated tube solar water heaters for domestic hot-water applications. These are the single-phase open thermosyphon system and the two-phase closed thermosyphon system. Our results show that the daily and annual thermal performance of the two-phase closed thermosyphon solar collector is slightly better than the single-phase open thermosyphon design. But the payback periods of the two are relatively the same because of the higher initial costs of the two-phase closed thermosyphon collector system. Although economically they are less attractive than the flat-plate type collector system, they are suitable for applications in advanced systems with higher temperature demands.     

Technical information

The centre of glass thermal performance of evacuated glazing is better than the performance of argon‐filled atmospheric pressure double glazings. Mitigation, or elimination of evacuated glazing edge effects will bring total window thermal performance on par, or better than, competing ‘superwindow’ options; thus increasing the commercial attractiveness of these glazings. The results of the computer‐based thermal modelling at the Universities of Sydney and Ulster compare well with each other and with the infrared thermography measurements at Lawrence Berkeley.     

Experimental investigation of solar heating and humidification system based on desiccant bed heat exchanger

In this article, an experimental investigation has been made on a solar heating and humidification system. In this system, an evacuated tube solar water heater is connected to the desiccant bed heat exchanger (DBHE) by connecting pipes. The evacuated tube solar water heater supplies required heat to the DBHE for the regeneration of desiccant material. Various types of solid and composite desiccant materials have been used in the DBHE to investigate their effect on the system performance. It has been found that the system obtained its best performance with silica gel with average humidification rate of 0.63?kg/h. The maximum temperature difference of process air has been found as 16°C at the flow rate of 295.2?kg/h.     

空调用太阳能集热器适用性分析

计算了平板集热器、真空管集热器、热管真空管集热器和CPC真空管集热器的太阳能利用系数,分析了几种太阳能集热器在空调系统中的适用性。结果表明,太阳能空调(热泵)系统集热器的热性能随着气象条件、热源温度的变化而变化,具有不同热源温度要求的系统应选用不同的集热器。     

MATLAB modelling and examination of the effect of heat capacity of basin and glass cover on performance of solar still by thermal models

There are numerous researcher-developed mathematical models for single slope passive solar stills which considered the effect of heat capacities of basin and glass cover as negligible. The negligence parameter also plays a vital role in the prediction of the thermal performance of the system. In this paper, an effort has been made to evaluate the cumulative yield, energy efficiency and exergy efficiency of a single slope passive solar still with and without considering the heat capacities of basin and glass cover by using various thermal models such as Dunkle’s model, Zheng Hongfei et al.’s model and Tsilingiris model. These models were studied and compared with and without considering the heat capacity of solar components such as basin and glass cover. The thermodynamic model of this system is developed, and executed in a MATLAB code. By comparing the theoretical values of the cumulative yield, energy efficiency and exergy efficiency, it was found that consideration of the heat capacities of glass cover and basin gives a higher output in all the thermal models.     

北京某商业步行街采光顶光热性能分析

为了对商业广场风雨步行街采光顶的光热性能进行整体评价,提出兼顾舒适、经济、节能三者的优化设计方案,现以北京某商业广场风雨步行街为实例,运用模拟计算软件对其步行街采光顶在无遮阳、采用内遮阳(实际采用的遮阳方式)、采用外遮阳这3种情况下分别进行模拟计算,分析其3种情况下步行街室内的采光效果、透入太阳辐射热程度,最后提出优化建议。     

A comparative performance analysis of solar heat exchangers for solar hot water application under controlled laboratory conditions

The paper presents the experimental performance evaluation of a novel retrofit heat exchanger (‘SolaPlug’) developed for solar hot water storage applications. The performance of this system was compared with a traditional dual-coil (‘Coil’) solar cylinder under controlled operating conditions. The tests were conducted under different solar-simulated conditions with a 30 and 20 evacuated tube collector. The results showed that after a 6-h test period, the average water temperatures within the store for the ‘SolaPlug’ system were 58.8°C and 40.5°C at 860 and 459?W?m^?2, respectively, and for the ‘Coil’ system were 60.5°C and 40.6°C when a 30 tube collector was used. The performance of the ‘SolaPlug’ system was marginally better than the ‘Coil’ system under the low solar input condition. Under high insolation condition, the overall ‘SolaPlug’ system efficiency was found to be 4.3% lower than that of the ‘Coil’ system. The ‘SolaPlug’ heat exchanger rating was 222?W?K^?1.     

聚光型真空集热管在太阳热水器中的应用

聚光型真空集热管,是在真空管外管下方的内壁镀以反射镜面。这种内置的反射镜面,既具有太阳能热水器反射板提高阳光利用率的效果,又避免了外置反射板积雪、积垢、增大风阻的弊端,其成本更得以大幅下降。应用聚光型真空集热管的热管式太阳热水器,由于采用了大直径外管,通过内置反射镜面的聚光作用,所用热管的数量大大减少,从而降低了热管式太阳热水器的产品成本,市场前景广阔,值得推广。