太阳能热水器与其他类热水器优缺点剖析

<正>太阳能热水器太阳能热水器把太阳光能转化为热能,将水从低温度加热到高温度,以满足人们在生活、生产中的热水使用。太阳能热水器按结构形式分为真空管式太阳能热水器和平板式太阳能热水器。目前我国以真空管式太阳能热水器为主。分类真空管式家用太阳能热水器:是由集热管、储水箱及支架等相关附件组成,把太阳能转换成热能主要依靠集热管。集热     

新型槽式跟踪太阳能集热器的中高温热利用研究

采用新型导热介质,主要介绍了集热装置的热性能实验方法,并着重对槽式跟踪太阳能集热器集热性能进行了研究及分析,通过对槽式跟踪热管真空管集热器理论值与试验值的比较,结果表明:利用导热油强化传热技术并结合热管技术,使得槽式跟踪太阳能集热器具有较高的集热效率,可产压力2 MPa,温度达200℃以上的饱和蒸汽。     

热管真空管太阳能集热器研究进展及应用

太阳能集热装置是将太阳辐射能转换为热能的设备,国内外学者对太阳能集热器的核心部件之一的真空管进行了广泛研究.本文首先介绍了热管真空管集热器工作原理并对部分影响集热器性能的性能指标、主要技术参数等进行探讨;其次分析了热管真空管集热器在使用中存在的问题并提出了解决途径,再次讨论了热管真空管太阳能集热器的应用;最后从集热器结...     

两种CPC热管真空管集热器的性能比较

基于CPC型太阳能集热器的发展现状,介绍了肋片型、导热油犁两种CPC热管真宅管集热器的结构,并对集热器进行了传热分析,得出集热器的瞬时效率方程.结果表明,导热油型CPC热管真李管集热器的效率明显高于肋片型CPC热管真空管集热器的效率,且加工工艺简单,成本相对较低.     

太阳能热水器选购指南

<正>市场上销售的太阳能热水器种类很多,按太阳能集热器种类来分,可分为真空管式和平板式;按结构分,可分为一体式和分体式;按制作工艺分,可分为承压式和非承压式。目前,我国最常见的大都是非承压真空管式家用太阳能热水器。面对眼花缭乱的热水器市场,消费者往往茫然而不知所措。在购买的时候,很多消费者都是通过卖家介绍买的,有很多不确定陛,那么如何理性选购一款家用太阳能热水器呢?消费者掌握一些选购方法后可以自行挑选,避免被"忽悠"。     

家用直膨式太阳能热泵热水系统试验研究

搭建家用直膨式太阳能热泵热水系统试验台,测试分析太阳辐照度、水箱设定温度、集热蒸发器面积等对系统性能的影响。研究发现:在太阳辐照度由780 W/m~2提高到900 W/m~2时,系统平均COP可提高8%左右;该系统相比于同工况下常规空气源热泵热水系统平均COP提高33.2%左右;水箱设定温度每提高5℃,系统平均COP降低12%左右,建议控制水箱温度在50～55℃;综合考虑系统经济性、加热时间及系统性能,建议将采用容积为150 L水箱的直膨式太阳能热泵热水系统的集热蒸发器面积控制在2.0～2.6 m~2。     

简讯

由北京市桑普技术公司最新研究生产的热管式真空太阳能集热管,经国内外大量工程实例证明,热管式真空管最适合应用于要求有大水量、高温热水或其他介质需求的工程用户。热管式真空管管内不走水,加热系统与循环系统独立分隔,     

北京桑普技术公司研发热管式真空太阳能集热管

由北京市桑普技术公司最新研究生产的热管式真空太阳能集热管，经国内外大量工程实例证明，热管式真空管最适合应用于要求有大水量、高温热水或其他介质需求的工程用户。热管式真空管管内不走水，加热系统与循环系统独立分隔，     

新型太阳能热管集热墙性能研究

建立了一种与建筑围护结构相结合的新型太阳能热管集热墙,该集热墙通过内置重力热管将太阳能由室外传给室内辐射板,并将辐射板作为室内采暖系统末端直接向室内散热。通过实验和数值研究表明,该系统集热效率较高,优化以后瞬时效率可达79.4%;当热管贴合面积与集热板或辐射板接触面积之比为18.4%时系统性能较高;通过旋转热管传热芯,夏季阻热性能较好。     

太阳能产品太阳能应成为重中之重

太阳能企业转型升级,首先要认清产品升级的方向。目前市场上的全玻璃紧凑型直插式和非承压太阳能热水器,已经无法再满足消费者日益膨胀的需求,太阳能产业向新能源的转型升级不可能靠单一产品完成。太阳能热水器的单一产品应该向智能化、全天候、健康水高端升级。更重要的是要研发生产分体承压与非承压可安装在屋顶、阳台与建筑完美结合的产品,除了真空管还有平板。总之,开发多元化的产品是转型升级的重中之重。     

A novel measurement theory for inventory of working fluid and vacuum pressure of heat pipe

Abstract

Heat pipes are transport mechanisms that can carry heat fluxes ranging from 10 W/cm² to 20 KW/cm² at extremely fast speeds. Therefore, heat pipes are widely used in 1U servers, notebooks, PCs, etc. A heat pipe is a heat removal device comprising a vacuum pipe that charges a certain amount of working fluid and seals the tube. Hence, the heat pipe performance depends not only on the geometric parameters such as wall thickness, tube material, and wick material but also on the thermal properties of the working fluid such as latent heat, vapor pressure, viscosity, and vacuum pressure.

Traditionally, the fluid inventory of heat pipes was measured by the lost weight method, that is measuring the weight of the heat pipe first, then, breaking the heat pipe, after drying in the oven, then weighting again, and the lost weight would be the weight of the working fluid. This paper presents a new methodological concept to measure the inventory by a basic energy mass balance equation. The Measurement theory not only calculates the fluid inventory but also the vacuum pressure data. The experimental results show that when the weight percentage of working fluid was larger than 10% of total pipe weight, the relative errors were within 4% when compared with the known inventory.     

Performance evaluation of single stand and hybrid solar water heaters: a comprehensive review

In this review, flat plate and concentrate-type solar collectors, integrated collector–storage systems, and solar water heaters combined with photovoltaic–thermal modules, solar-assisted heat pump solar water heaters, and solar water heaters using phase change materials are studied based on their thermal performance, cost, energy, and exergy efficiencies. The maximum water temperature and thermal efficiencies are enlisted to evaluate the thermal performance of the different solar water heaters. It is found that the solar water heaters’ performance is considerably improved by boosting water flow rate and tilt angle, modification of the shape and number of collectors, using wavy diffuse and electrodepositioned reflector coating, application of the corrugated absorber surface and coated absorber, use of turbulent enhancers, using thermal conductive working fluid and nanofluid, the inclusion of the water storage tank, and tank insulation. These items increase the heat transfer area and coefficient, thermal conductivity, the Reynolds and Nusselt numbers, heat transfer rate, and energy and exergy efficiencies. The evacuated tube heaters have a higher temperature compared to the collectors with a plane surface. Their thermal performance increases by using all-glass active circulation and heat pipe integration. The concentrative type of solar water heaters is superior to other solar heaters, particularly in achieving higher water temperatures. Their performance improves by using a rotating mirror concentrator. The integration of the system with energy storage components, phase change materials, or a heat pump provides a satisfactory performance over conventional solar water heaters.

Graphical abstract

Modification of solar water heaters

     

有机热载体炉蛇形管失效原因分析

采用金相检验、力学性能测试、导热油化验等方法对某有机热载体炉发生火灾的原因进行了分析。结果表明：该事故的原因为使用的导热油标号过低,导致导热油在蛇形管内碳化、结焦,蛇形管过热,并产生蠕变裂纹,最终强度不足发生爆管。     

内聚光膜式全玻璃真空太阳集热管真空品质表征方法

本文计算了内聚光膜式全玻璃真空太阳集热管在烘烤排气过程中的排气量,提出了一种定量表征其真空品质的方法,然后通过集热管高温烘烤———加速老化实验对其真空性能进行了验证,首次利用内聚光膜式集热管高温烘烤过程中铝膜温度随老化时间的变化曲线表征其真空性能,且效果良好。实践表明,这种定量分析结合实验验证的方法表征内聚光膜式集热管真空品质是行之有效的。     

Energy and exergy evaluation of an integrated solar heat pipe wall system for space heating

In this paper, an integrated solar heat pipe wall space heating system, employing double glazed heat pipe evacuated tube solar collector and forced convective heat transfer condenser, is introduced. Thermal performance of the heat pipe solar collector is studied and a numerical model is developed to investigate the thermal efficiency of the system, the inlet and outlet air temperatures and heat pipe temperature. Furthermore, the system performance is evaluated based on exergy efficiency. In order to verify the precision of the developed model, the numerical results are compared with experimental data. Parametric sensitivity for design features and material associated with the heat pipe, collector cover and insulation is evaluated to provide a combination with higher thermal performance. Simulation results show that applying a solar collector with more than 30 heat pipes is not efficient. The rate of increasing in temperature of air becomes negligible after 30 heat pipes and the trend of the thermal efficiency is descending with increasing heat pipes. The results also indicate that at a cold winter day of January, the proposed system with a 20 heat pipe collector shows maximum energy and exergy efficiency of 56.8% and 7.2%, which can afford warm air up to 30°C. At the end, the capability of the proposed system to meet the heating demand of a building is investigated. It is concluded that the best method to reach a higher thermal covered area is to apply parallel collectors.     

高性能SS-AlN金属陶瓷真空太阳集热管的制备

采用真空磁控溅射沉积SS-AlN金属陶瓷太阳选择性吸收涂层.涂层光学功能层的制备,先采用铜靶溅射Cu红外反射层;再采用不锈钢(SS)和铝两金属靶在Ar和N2的混合气体中同时溅射沉积SS-AlN金属陶瓷吸收层;最后采用Al靶在Ar和N2中反应溅射沉积AlN减反射层.金属陶瓷吸收层由高、低SS体积份额的两吸收子层组成.优化溅射镀膜工艺参数获得高性能吸收涂层,太阳吸收比α(AM1.5)高达0.956±0.003(国标GB:α≥0.86),比GB高10％;红外发射比ε仅为0.043±0.003(GB:ε≤0.08).制备成φ58×2100 mm全玻璃真空太阳集热管,80℃平均热损系数ULT仅为0.47±0.01 W/m2℃ (GB:ULT≤0.85 W/m2℃),比GB低0.38W/m2℃,性能提高45％.制备的真空集热管具有良好的真空品质,集热管内管加热350℃恒温480 h后,吸气镜面轴向长度平均消失率仅为2～3％,集热管真空品质优于GB高达100倍以上(GB:350℃恒温48 h,镜面消失率≤50％).     

空间低温热管的设计与实验研究

介绍了为空间辐射制冷器研制开发的一种干道吸液芯氮气低温热管 ,该热管直径为6mm ,长度210mm ,工作温度80 .0～120 .0K ,最大传热功率可达2.5W ;并对其传热性能进行了实验研究。实验结果表明低温热管的传热性能远远优于固体的导热性能 ,完全能够满足辐射制冷器冷焦面耦合需要     

Beschichtungen und Evakuierung von Vakuum‐Solarkollektoren

Coating and Evacuation of Solar Collector Tubes The company NARVA, a traditional German producer of fluorescent lamps, has started in 2005 the development of a new vacuum absorber tube for collecting of solar energy for warmth of buildings or for process heat. By adapting the experience of lamp making NARVA is using their self produced soda lime glass, coated with Siliciumdioxide nano particles for the collector tubes. This coating gives better transmission, less corrosion and a behaviour like safety glass in case of destruction. A other interesting item in the development of the vacuum process is the „light oven”︁. By use the light oven it was possible to reach the necessary temperature on the absorber fin for an effective desorption of the water molecules from the surface of the fins and to reach the target vacuum.     

同轴式套管换热器应用于家用循环式热泵热水器的特性试验研究

分析以采用普通高效换热管的同轴式套管换热器为冷凝器的热力特性,并针对其运用在家用循环式热泵热水器的特点,试验研究采用该套管换热器的家用循环式热泵热水器的特性,得到在名义制热工况及冷却水进口温度为30℃条件下,不同水流量所对应的冷凝负荷、功率等特性及性能。结果可应用于家用循环式热泵热水器的开发设计。     

The thermal performance of an electrochromic vacuum glazing with selected low-emittance coatings

An electrochromic (EC) vacuum glazing (VG) is formed when a vacuum glazing is combined with an electrochromic glazing. Three glass panes are required, two of which may have a low-emittance coating separated by a pillar array, the space formed being evacuated and sealed contiguously by a metal edge seal, the third glass pane with an EC layer is sealed to the evacuated glass unit. With the EC glazing installed with the electrochromic component facing the outdoor environment, for an incident solar radiation of 300 W m^− 2, when the EC layer is opaque for winter conditions, the inside glass pane of the unit due to solar radiation absorbed by the low-emittance coatings within the vacuum gap and electrochromic layer is a heat source with heat transferred from the glazing to the interior environment.