太阳能热水系统“国标”出台

为了促进我国太阳能热水器产业的发展,提高太阳能热水器的产品质量,引导太阳能热水器产业的技术进步,指导生产,规范市场,保护消费者利益,国家标准化管理委员会批准公布了4项有关太阳能热水系统的国家标准:《家用太阳热水系统热性能试验方法》(GB/T18708-2002);《太阳热水系统设计、安装及工程验收技术规范》(GB/T18713-2002);《太阳集热器热性能室内试验方法》(GB/T18974-2003)和《家用太阳热水系统技术条件》(GB/T19141-2003)。以上标准已经分别于2002年10月1日、2002年11月1日、2003年7月1日和2003年10月1日起正式实施。这4项标准分…     

太阳热水器/集热器热性能测试系统的设计与实现

从工业生产及科学研究中测试的实际需要出发,对太阳热水器/集热器热性能测试系统的硬件、软件设计及实现进行了简要概述.通过将数据采集器与计算机连接起来,实现了数据的自动采集与自动处理,大大提高了试验过程的智能化程度.     

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.     

带喷射器的CO2热泵热水器的循环特性研究

设计了适用于CO2热泵热水器的喷射器。分析了喷射器内部CO2流体压力、速度的变化趋势。建立了基于等压混合理论的喷射器模型,并对带喷射器的CO2热泵热水器系统进行热力学计算和火用损失分析。对带喷射器的热泵系统和带热力膨胀阀的传统热泵系统进行性能比较。考查了喷射系数、气体冷却器出口温度、蒸发温度等参数对系统制热系数的影响。     

燃气热水器性能与关键结构参数关联性分析

对11台负压燃气热水器样品和13台正压燃气热水器样品的燃烧器、热交换器和燃烧腔体结构参数进行测绘统计,对样品的热负荷、热效率、热水产率、烟气排放数据进行实验测试,对结构参数与性能数据之间的关联性进行分析。合理选择燃烧器、热交换器、燃烧腔体的结构设计参数,可以有效保证燃气热水器整机性能。对额定热负荷30 kW及以下、额定产热水能力16 kg/min及以下的燃气热水器和额定热负荷31 kW及以上、额定产热水能力16 kg/min及以上的燃气热水器,分别给出了建议的燃烧器火排数量、设计火孔热强度、翅片数量、热交换器容积与燃烧腔体容积之比、热交换器单位容积额定热负荷、容积热强度等关键结构参数的设计参考范围。对于额定热负荷30 kW及以下、额定产热水能力16 kg/min及以下的燃气热水器,一般采用负压结构;对于额定热负荷31 kW及以上、额定产热水能力16 kg/min及以上的燃气热水器,一般采用正压结构。     

外窗遮阳系统太阳得热系数及其对空调负荷的影响

为研究外窗遮阳系统的太阳得热系数全年变化规律及外窗遮阳系统对空调负荷的影响,以南京市为例,对外窗遮阳系统的太阳得热系数在全年逐月的变化规律、3种外窗遮阳系统在不同朝向方位角上的年太阳得热系数及外窗遮阳系统对房间空调负荷的影响等进行了研究。结果表明:南向双玻中空外窗遮阳系统全年的月太阳得热系数相差最大达到0.10,且夏季太阳得热系数比冬季低13%;采用中置卷帘遮阳和外置水平百叶遮阳的外窗系统空调节能效果较好;此外,外窗遮阳系统的年太阳得热系数与空调全年累计负荷存在正相关关系,且采用中置卷帘和内置百叶遮阳的南向外窗,其全年累计负荷降低率大于采用相同遮阳形式的西向外窗。     

空气能热泵热水器现状

空气能热泵热水器是继电热水器、燃气热水器及太阳热水器之后国内第4种热水器。它对可再生的空气能利用率可达60%～70%,是一种节能效果显著的设备。以空气为热源的热泵,是利用少量电力,通过热力循环将空气中的低温热提升为高温热,当以热水的形式出现时,便成空气能热泵热水器。空气能热泵热水器与传统的燃气热水器和电热水器相比,不仅安全,而且节能环保,即使与太阳热水器相比也有明显的优势——它一改传统太阳能产品只依赖太阳光直射或辐射来吸收能源的方式,利用设备内的冷媒,从空气中采集热能并通过热交换器使冷水升温。空气能热泵热水器在…     

全玻璃真空管型家用太阳能热水器热性能影响因素试验研究

利用研制开发的家用太阳能热水器热性能测试装置对全玻璃真空管型太阳能热水器热性能的影响因素进行了测试研究。通过测试,研究分析了单位面积容水量、真空管管间距、真空管长度、贮热水箱保温厚度等因素对全玻璃真空管型家用太阳能热水器热性能的影响。研究结果表明,单位面积容水量对家用太阳能热水器的热性能影响较大;在目前的保温工艺水平下,采用50 mm厚的聚氨酯保温就可以达到较好的保温效果。     

整体式太阳热水器结构改进研究进展

介绍了整体式太阳热水器(ICSSWH)结构改进研究进展.通过结构改进,强化热分层,降低对流热损失,提高聚光比和集热率;通过材料选择,改善内部传热,提高吸收率,降低辐射热损失.整体式太阳热水器(ICSSWH)在农村地区具备一定竞争优势.     

平板太阳热水器集热涂层研究

结合国内外太阳热水器的发展史,综述了平板太阳热水器集热涂层的种类、制备方法、发展现状,分析了涂层行业内存在的问题与发展瓶颈,对未来涂层的发展趋势进行预测,并阐述了涂层性能检测的相关标准。     

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.     

Wind loads on residential and large-scale solar collector models

Previous studies on solar water heaters have mainly focused on the thermal efficiency of various types of solar collectors, and there has been limited work done on the aerodynamic characteristics of solar collectors or their supporting structure. However, typhoons are among the natural hazards that have a costly impact on residential construction and solar water heaters are usually installed on the flat roofs of buildings for hot water production. Thus, the safety of solar water heaters under severe wind load during typhoon season is a critical issue in the promotion of solar water heaters. In this study, an experimental program was conducted to examine the aerodynamic characteristics of solar collector models (residential and large-scale solar water heaters). The unit sectional uplift coefficient with or without a guide plate is also addressed. Measurements of mean longitudinal and spanwise surface pressure were performed. The data show that the presence of a water storage tank (or a horizontal cylinder) tends to reduce the suction force on the upper surface within the first half of the tilt flat panel (solar collector). Stronger negative longitudinal differential mean pressure is observed for the test case of a tilt flat panel only, which corresponds to strong wind load. The inverted U-shape of mean spanwise pressure distributions is also noted. With a guide plate, less wind load and more uniformity of spanwise differential mean pressure distributions are associated with a larger projected area of a guide plate on the lower surface of a tilt flat panel. This is essentially attributed to the attenuation of corner vortices and a decrease in uplift force.     

单角钢压杆的屈曲及稳定计算

在钢结构工程中经常采用等边或不等边单角钢作为轴心受压构件,现行钢结构设计规范(GB50017—2002)提供了等边单角钢压杆的截面类别及稳定计算方法,但对不等边单角钢压杆的规定相对粗糙。本文根据弹性稳定理论和角钢截面特征规律,推导了等边及不等边单角钢轴心受压构件的屈曲条件和长细比简化计算方法,并给出了稳定设计方法。扭转屈曲换算长细比仅与角钢肢宽与肢厚的比值有关,这使得弯扭屈曲换算长细比的计算也进一步简化。经过验证,该方法简单实用,可供工程设计参考。     

太阳能热水器比较经济的防雷措施

介绍了太阳能热水器的结构及运行原理,分析了安装在屋顶的太阳能热水器容易遭受到雷击的因素,针对不同类型太阳能热水器及其安装位置,优化了防直击雷和防雷电波侵入措施,使其更加经济实用。     

太阳能热水器的雷电防护

通过分析太阳能热水器遭雷击的方式,针对目前太阳能热水器防雷安全隐患较大的现状,从防直击雷、防雷电感应及电磁波脉冲等方面进行了论述,并提出了有效防护的措施,以减少雷电灾害对太阳能热水器的使用造成的危害。     

生活热水制备方式的一次能耗比较分析

以电热水器、燃气热水器、空气源热水器和太阳能热水器4种常用的生活热水制备方式为研究对象,比较分析了一次能源消耗情况,为选用更为节能的生活热水制备方式提供参考。     

高校学生宿舍热水系统建设模式选择

学生生活热水是校园耗能的重要部分之一,合理选择生活热水系统的热源是节能校园建设的一个关键因素。空气能热水器被称为"第四代热水器",与之前"燃气热水器"、"电热水器"、"太阳能热水器"相比,在各方面均有非常明显的优势。目前高校采用较多的太阳能+空气能热水系统是一种最安全的系统,其建设模式多采用BOT投资模式。     

A numerical investigation of three different thermosyphon solar water heating systems

This work presents a theoretical evaluation of the performance of three types of thermosyphon solar water heating (TSWH) systems with flat-plate collectors considering different weather conditions. The flat-plate solar collectors considered are the absorber–pipe lower bond configuration (Type I), the absorber–pipe side bond configuration (Type II) and the absorber–pipe upper bond configuration (Type III). The performance of the three heaters have been investigated numerically under the same conditions. The average values of the energetic and exergetic efficiencies, for one of the weather conditions are: 39.47% and 18.21% for Type I, 34.86% and 15.45% for Type II, 32.28% and 13.8% for Type III. This study reveals that, the thermal performances obtained with Type I TSWH is always greater than the two others, and that this configuration leads to an improvement in the efficiency–temperature rise couple, followed by Type II TSWH system.     

Experimental analysis of the performance of a solar flat plate water heater with and without internal fins

Generally increasing, an increase in the surface area will increase the heat transfer capability of a solar collector and possibly its efficiency. Conventional solar water heaters have longitudinal fins attached externally to the collector tubes for reaping the benefits of enhanced heat transfer. Attempts have been made towards providing internal fins (spirally grooved copper tubes), in addition to the existing external fins for analysing its influence on efficiency and outlet temperature. Two identical solar water heaters with a capacity of 25?L per day were designed and fabricated, one with a collector with plain (unfinned) internals and another with internal grooving (finned tube). The paper details the temperature profile observed in the two collectors, variation of thermo-siphon mechanism and change in efficiency of the solar water heaters with respect to time. It has been observed that providing internal fins had led to an increase in efficiency of about 4.5% as compared to conventional plain tubes.     

Thermal performance analysis and economic evaluation of roof-integrated solar concrete collector

This paper examines the thermal performance of a roof-integrated solar concrete collector for reducing heat gain to a house and providing domestic hot water. The solar concrete collector is made of PVC pipes embedded in deck slab or concrete roof. No glazing on the top of the solar concrete collector or insulation at the back has been used as in conventional solar water heaters. To compare the energy saving, two test rooms of 2.3 m width, 2.5 m length and 2.5 m height were built. In the first room, the reinforced cement concrete (R.C.C.) slab was used as deck slab whereas the second room was equipped with a cement concrete solar collector. The experimental results showed that the cement concrete solar collector is extremely interesting as it can produce up to 40 l of hot water per day at water temperatures ranging from 40 to 50 °C. A mathematical model based on the conservation equations of energy is developed to predict the performance of the cement concrete solar collector. There is reasonable agreement from the comparison between measured data and predicted results. The economic analysis indicates that the payback period is rather fast.