太阳能热水器得热量的两种测定方法比较

采用排水法和混水法测定太阳能热水器得热量,结果发现排水法测得的得热值明显高于混水法.分析结果表明,这种差异主要因为两种方法之间原理和方法的不同所致,排水法测定的是热水器包括水箱和集热器存留水的全部得热量,混水法测定的仅是可供用户利用的水箱得热量,针对试验样品,提出了混水法中未计入热量的有效解决办法.     

太阳能光伏光热一体化系统的实验研究

为提高太阳能的利用率同时得到可资利用的热水和电力，将小型贮能式光伏系统与家用平板型太阳能热水器结合起来，把光优电池组件层压在热水器的扁盒式铝合金集热板上，构成一套光优光热(PV／T)一体化系统，并在合肥地区进行了自然循环模式下的光电光热性能测试。实验结果表明，在晴朗或多云的天气条件下实验系统日平均热效率可达40％，日平均发电效率约9．5％，系统综合性能效率多在60％以上，比单独的光伏或热水系统效率有显著提高。     

浅谈家用太阳热水器热性能测试

如何评价与检测家用太阳热水器的热性能呢？国家质量监督检验检疫总局于2002年4月28日发布了国标GB／T 18708—2002《家用太阳热水系统热性能试验方法》，通过此试验方法可得到太阳热水器能量输入一输出曲线图，它全面系统地反映了在不同的季节、不同的太阳辐照量条件下的太阳热水器能量输入一输出特性，实现了我国太阳热水器产品的热性能试验与国际接轨。     

对日有用得热量试验条件的实验研究

通过对多台家用太阳热水系统多次单天热性能测试结果的分析,得到日有用得热量的测量误差,以及日有用得热量与太阳辐照量H、日平均环境温度与开始温度的温差(tad-tb)的关系。通过讨论认为在试验条件中将太阳辐照量H降至16MJ/m2对测试结果无影响,测试时可考虑适当放宽tad的范围,通过限制(tad-tb)值的大小来减少tad变化对q17的影响,增加有效的检测天数。     

热泵辅助型太阳能热水系统动态性能评价研究

通过空气源热泵和太阳能热水系统两个单元的独立实验得出空气源热泵辅助型太阳能热水系统整机COP随全天太阳辐照量以及平均环境温度变化的实验模型。利用该模型可将随机气象条件下得到的实验值转换成某一标准气象条件下的评价值,从而对产品性能进行准确评价。对两台不同型号样机进行的实验结果表明:该模型得到的评价值偏差小于3%,该评价方法可用于空气源热泵辅助型太阳能热水系统整机COP的评价。     

家用太阳热水器热性能试验方法探讨

一前言国家推荐标准ＧＢ／Ｔ１２９１５ ９１“家用太阳热水器热性能试验方法”中采用平均日效率的概念来反映太阳热水器获取能量的性能。平均日效率高的热水器意味着其平均热性能较好 ;反之 ,热性能较差。用户和质量检测部门也以此作为反映热水器质量的主要依据。但我们在长期的测试工作中发现 ,该标准有以下几方面问题值得商榷。１ 日平均热效率从用户要求和研究角度两个方面仔细考虑 ,发现用户使用太阳热水器 ,主要关心在不同气象情况下 ,每天能提供热水的温度和水量 ,以及每天不同时间水箱中的水温。而从研究角度 ,关心的是热水器在不同…     

一种新型的与建筑一体化太阳能双效集热器系统的实验研究

提出了一种新型的与建筑一体化太阳能双效集热器系统,该系统有两种工作模式:被动采暖工作模式和集热水工作模式。由系统工作在被动采暖工作模式下的实验结果可以得到:系统房间内空气存在温度分层现象,测试期间上下位置最大温差为4.2℃,平均温差约为2.7℃;系统在被动采暖工作模式下工作时对房间温度的提高作用明显,实验测试结果显示,实验期间系统房间平均温度达到24.7℃,相对环境温度升高平均达到19.9℃。通过系统以自然循环方式工作在集热水工作模式下的实验测试结果,可以得到实验期间在集热水工作模式下系统的热效率为52.8%,集热器单位面积太阳得热为4.16MJ/m~2。     

家用太阳热水系统的热性能试验方法--GB/T 18708-2002国家标准介绍

我国自改革开放以来，经济发展迅速，人民生活水平日益提高，真空管太阳集热器、太阳热水系统产品的生产水平和数量不断提高，我国已成为世界上真空管太阳集热器、太阳热水系统产品的主要生产与使用国家。２００２年４月２８日国家质量监督检验检疫总局发布了GB／T１８７０８－２００２“家用太阳热水系统热性能试验方法”。通过试验给出太阳热水系统的得热量曲线与方程，可以预测该太阳热水系统在使用地区的全年得热量（MJ）；给出了太阳热水系统贮热水箱的平均热损系数（W／K）。新国标的实施，会促进我国太阳能热利用事业的发展。太阳…     

平板式与真空管式太阳热水器热性能分析比较

在太阳热水器中依据吸热体的形状,可将其分为平板式太阳热水器和真空管式太阳热水器两大类。由于吸热体形状的不同,导致这两类热水器在热性能上各有差异。在家用太阳热水器热性能测试的国标中,热性能指标主要有日平均效率η d、平均热损系数 UL和非稳态效率方程。其中,日平均效率η d描述了在正常天气状况 (晴天 )下,一日内在热水器采光面上接收到的太阳辐射量中转化为提高水箱水温的热量的百分比;平均热损系数则反映了在无日照等条件下,热水器整体的保温性能;而非稳态效率是上述的热转换效率在不同时点的体现,非稳态效率方程则是…     

村镇住宅建筑太阳能供热系统技术经济分析

以桃李坪村为例分析了村镇住宅建筑的3种太阳能利用形式,即:①太阳能全年热水系统;②太阳能采暖及热水联合系统;③节能建筑(即达到西安市节能65%标准要求)太阳能采暖及热水联合系统。利用动态年计算费用法比较了以上3种利用形式在西安、拉萨及北京地区的技术经济性。研究表明:在西安的太阳辐照条件下,利用太阳能进行采暖的最优集热器面积为3m~2(此时采暖季太阳能采暖率为0%),不宜采用;但利用太阳能供应生活用热水可保证技术、经济性能都较优,具有显著的经济、环境及社会效益。     

基于层次分析法的太阳能利用技术综合评价

本文首先利用一个非稳态传热模型对同一环境条件下光伏光热一体化（PV/T）系统、光伏系统（PV）和太阳能热水器的能效进行分析,然后采用层次分析法（AHP）对不同品质终端能源输出的太阳能利用系统的能效统一表征,并以北京、广州和银川为代表的不同城市自然环境及用电价格为条件的三种情景,对三种太阳能利用系统的综合能源利用效率、累计净收益和投资回收期进行分析。结果表明,太阳能利用系统的经济性不仅受到系统能源利用效率和成本的影响,系统所在地的自然环境和电价水平也会引起系统经济性发生变化,因此考虑多种因素的综合评价可以为太阳能技术推广提供更客观和准确的参考。     

A new type of phase change heat storage tank in solar energy combination system

介绍了一种新型笼屉式相变蓄热水箱,通过实验测试对比分析相变蓄热水箱与普通蓄热水箱对太阳能组合系统的太阳能保证率及系统能效比的影响。实验表明：同等水箱容积,使用相变蓄热水箱时太阳能集热系统的小时集热量为普通蓄热水箱的3.7倍,相变蓄热水箱有利于提高太阳能保证率及系统能效比。在太阳能辐照强度相似的情况下,相变蓄热水箱会使太阳能保证率平均提高72%,使系统能效比平均提高26%。同时相变蓄热水箱可减少夜间水箱上部的热损失,使水箱上部水温降减少50%。     

Numerical simulation and experimental validation of indirect expansion solar-assisted multi-functional heat pump

A novel indirect expansion solar-assisted multi-functional heat pump (IX-SAMHP) system which composes of the multi-functional heat pump system and solar thermal collecting system is proposed and studied in this paper. This system can fulfill space heating, space cooling and water heating with high energy efficiency by utilizing solar energy. For solar water heating mode and solar space heating mode, a dynamic model is presented and validated with the experimental results. The simulation results show good consistency with the experimental data, and the established model is able to predict the system performance at a reasonable accuracy (with the root mean square deviations less than 5%). On this basis, the performances of the IX-SAMHP system are investigated under different parametric conditions. For solar water heating mode, simultaneously operating the solar thermal collecting system and multi-functional heat pump system can be an energy efficiency method. With the solar irradiation rising from 0W/m² to 800W/m², the COP increases from 2.35 to 2.57. In solar space heating mode, the effect of the mass flow rate of water in evaporator is investigated. To balance the heating capacity and COP, the mass flow rate of water should be adjusted according to different temperature demands and heat load.     

Performance study of a photovoltaic solar assisted heat pump with variable-frequency compressor – A case study in Tibet

The performance of a photovoltaic solar assisted heat pump (PV-SAHP) with variable-frequency compressor is reported in this paper. The system is a direct integration of photovoltaic/thermal solar collectors and heat pump. The solar collectors extract the required thermal energy from the heat pump and at the same time, the cooling effect of the refrigerant lowers the working temperature of the solar cells. So this combined system has a relatively high thermal performance with an improved photovoltaic efficiency. To adapt to the continuously changing solar radiation and ambient temperature conditions, the refrigerant mass flow rate should match the heat gain at the evaporator accordingly. A variable-frequency compressor and an electricity-operated expansion valve were used in the proposed system. Mathematical models were developed to evaluate the energy performance of the combined system based on the weather conditions of Tibet. The simulation results indicated that on a typical sunny winter day with light breeze, the average COP could reach 6.01, and the average electricity efficiency, thermal efficiency and overall efficiency were 0.135, 0.479 and 0.625 respectively.     

太阳能热水器传热传质和强化传热研究

在低温太阳能光热光伏联合应用试验台的基础上,结合GB/T 17049—2005,利用Gambit、Ansys Fluent和Tecplot软件,对全玻璃真空管太阳能热水器进行传热传质和强化传热分析。结果表明:所建立的二维数值计算模型,能准确反映同一条件下,全玻璃真空管太阳能热水器的变化趋势;在数值模拟基础上,确定了单面受热时的最佳安装角度为51°,加装反光板类似双面受热的最佳安装角度为38°;在粗略估算和细化分析的基础上,确定了不同真空管结构的最佳导流板长度及安装位置;通过实验和数值模拟,确定了58mm×1 800mm为优化的全玻璃真空管结构。     

Heat transfer performance of an external receiver pipe under unilateral concentrated solar radiation

The heat transfer and absorption characteristics of an external receiver pipe under unilateral concentrated solar radiation are theoretically investigated. Since the heat loss ratio of the infrared radiation has maximum at moderate energy flux, the heat absorption efficiency will first increase and then decrease with the incident energy flux. The local absorption efficiency will increase with the flow velocity, while the wall temperature drops quickly. Because of the unilateral concentrated solar radiation and different incident angle, the heat transfer is uneven along the circumference. Near the perpendicularly incident region, the wall temperature and absorption efficiency slowly approaches to the maximum, while the absorption efficiency sharply drops near the parallelly incident region. The calculation results show that the heat transfer parameters calculated from the average incident energy flux have a good agreement with the average values of the circumference under different boundary conditions. For the whole pipe with coating of Pyromark, the absorption efficiency of the main region is above 85%, and only the absorption efficiency near the parallelly incident region is below 80%. In general, the absorption efficiency of the whole pipe increases with flow velocity rising and pipe length decreasing, and it approaches to the maximum at optimal concentrated solar flux.     

太阳能集热器热性能动态测试方法研究

对太阳能集热器热性能动态测试方法进行了介绍,并对该方法的数学模型进行了分析;探讨了各项参数在方程中的作用、可以忽略的条件等;分析了稳态测试方法严格规定试验条件的必要性及原因,并对方程的数值求解进行了分析与推导。对同一台太阳能集热器分别进行动态和稳态测试方法的试验数据进行了不确定度分析,对试验结果进行了分析和对比,并分析了太阳能集热器效率曲线截距的差异以及在不同归一化温差处集热器瞬时效率曲线差异的深层次原因。     

基于XR修正的回转式空气预热器换热效率计算方法

依据逆流换热器换热理论模型,基于换热器无因次变量效能、传热单元数和热容量比之间的关系,对回转式空气预热器换热过程进行分析,提出基于XR修正的回转式空气预热器换热效率计算方法。根据某600 MW机组的空气预热器的设计参数及运行数据,利用该计算方法求解得到实际运行工况换热效率。并对该空气预热器进行了蓄热元件更换、密封间隙调整等改造,对改造前后实际运行工况换热效率进行计算。结果表明：未修正的换热效率与XR有较强的相关性,修正后的换热效率离散程度降低,更能反映空气预热器本身的换热能力。不进行修正情况下,改造前、后的平均换热效率分别为67.6%和67.4%,与设计值69.7%有较大的差距,不能体现出空气预热器改造的效果。通过XR修正,改造后的平均换热效率69.3%与设计值69.7%基本相当,高于改造前的平均换热效率,基本达到改造预期效果。该计算方法可更准确的评价空气预热器的实际性能及改造效果。     

Outdoor test method to determine the thermal behavior of solar domestic water heating systems

The dynamics of the market, the generation of new promotion programs, fiscal incentives and many other factors are to be considered for the massive application of solar domestic water heating systems (SDWHS) mainly of the compact thermosiphon type, makes it necessary to choose simple and inexpensive procedure tests that permit to know their characteristic thermal behaviors without an official standard being necessary. Moreover, it allows the comparison among systems and offers enough and reliable information to consumers and manufacturers.In most developing countries, an official national standard for SDWHS is not available, therefore it is necessary to adopt an international test procedure in which the cost and time of implementation is very important. In this work, a simple and inexpensive test method to determine the thermal behavior of SDWHS is proposed.Even though these procedure tests do not have an official standard structure they permit, by comparing different solar systems under identical solar, ambient, and initial conditions, the experimental determination of: (a) the maximum available volume of water for solar heating; (b) water temperature increment and available thermal energy at the end of the day; (c) temperature profiles (stratification) and the average temperature in the storage tank after it is homogenized; (d) the average global thermal efficiency; (e) water temperature decrement and energy lost overnight; and (f) the relationship between hot water volume and solar collector area as function of the average heating temperature. An additional proposed test permits to know the heat losses caused by the reverse flow in the collector loop. These tests will be carried out independently of the configuration between the solar collector and the storage tank, the way the fluid circulates and the type of thermal exchange. The results of this procedure test can be very useful, firstly, for the local solar manufacturers’ equipment in order to design and optimize its products comparing their systems against a reference system under identical test conditions and secondly, by the consumers in order to select the most suitable system. The resulting experimental data for a particular thermosiphon system is presented and discussed.     

蜂窝热管平板式太阳能热水器的实验研究

把蜂窝技术和热管技术结合起来应用于平板式太阳能热水器，可以大大减少热损失，提高日平均效率。经多次实验证明，蜂窝热管平板式太阳能热水器的日平均效率可以比真空管式热水器的高，热损系数则要小很多，具有推广应用价值。