如何识别和选购太阳能热水器

人口、资源、环境是当今社会面临的三大问题，已引起各国政府高度重视。大力开发清洁、无公害的可再生能源，改善用能结构，是实现绿色革命的一条必由之路。太阳能热水器产业正是顺应当今时代的发展，成为新兴产业突起的一支异军。一、太阳能热水器发展简况我国太阳能热水器的发展，大致经历了三个阶段：第一代是闷晒式太阳能热水器，诞生于五、六十年代，其缺点是水容量小、热效率低、保温性能差、寿命短、产品使用受季节或气候的影响大，但因其省电节能、操作简单、价格低廉，在偏远农村仍有一定的市场空间；第二代是平板式太阳能集热水器…     

太阳能供热水的经济性浅析

通过对3个类别5种品牌热水器供热水经济性比较，在使用寿命期内，最后算总帐，太阳能热水器，尤其是真空玻璃管式和热管式真空玻璃管太阳能热水器供热水，要远远好于其它形式的热水器。     

我国太阳能热水器环境政策评估

我国太阳能热水器产量和保有量居世界第一,但普及率及市场占有率较低,且缺乏对太阳能热水器的补贴和税收优惠,太阳能热水器的环境效益被大大低估。运用可再生能源发展阶段理论识别出我国太阳能热水器产业处于从商业化初期向成熟化过度阶段,目前该产业仍需要国家支持。建议政府对社会弱势群体购买太阳能热水器给予补贴,并对有一定规模的太阳能热水器企业给予环境效益的补贴。     

真空玻璃盖板热管平板式太阳能热水器的研制

介绍了研究成功的采用真空玻璃盖板的热管平板式太阳能热水器，测试了其性能，并与全玻璃真空管太阳能热水器和蜂窝热管太阳能热水器进行了比较。实测得到，真空玻璃盖板热管平板式热水器的日平均效率比后两分别大13．3％和6．5％，平均热损系数比后两分别小52．5％和21．5％。真空玻璃盖板平板式太阳能热水器性能优越，有很好的应用前景。     

快接管件在太阳能热水器中的应用

一太阳能热水器管道连接方式的发展及前景太阳能热水器经过近二十年的发展,管路连接也经历了几个阶段:初期,没有针对太阳能热水器的使用环境而专门设计的管路与配件,只能借鉴现有的水暖管路配件。在当时,应用最多的是镀锌管路配件。采     

新型U型真空管阳台式太阳能热水器

在分析目前太阳能热水器产品安装及使用中存在问题的基础上，提出解决方法，开发了一款新型U型真空管阳台式太阳能热水器。介绍了目前太阳能热水器产品的构成与分类，详细分析了新型U型真空管阳台式太阳能热水器的原理、结构及特点，并对其热性能进行测试，结果完全符合国家标准，满足目前太阳能热水器市场的需求。     

热水器的效益和发展

太阳能热水器是目前太阳能利用中最成熟,应用最广的装置。近几年来,由于国际石油价格下跌的影响,资本主义国家太阳能热水器行业很不景气。如美国从事热水器生产的企业一大半都倒闭了。不少人担心国际太阳能利用的萧条景象会影响我国,而事实上我国的太阳能热水器却一直在稳步发展。“六五”期间我国太阳能热水器推广应用量每年以14—32%的速度递增。全国从事太阳能研究的科研单位已发展到138个,生产单位108家,几乎所有的省、市、自治区都在从事太阳能利用的开发工作。可以预见,太阳能热水器作为一种商品,将会有一个很大的潜在市场。为适应这一形势发展的需要,横向联合,走行业发展的道路势在必行。利用现状1980年以前,我国太阳能热水器推广应用累计量     

太阳热水器静电除垢装置研制

太阳热水器在运动过程中的结垢和座蚀等问题会造成传热恶化，严重影响热水器的各项性能指标，介绍了在太阳能热水器中安装采用静电阻垢、防腐蚀技术研制的小型静电水处理装置，该装置由脉冲高压直流电源和水处理器两部分组成。阻垢、防腐蚀对比试验在两台12D18L太阳能热水器上进行，运行3个月，一台安装静电水处理装置，一台不安装。测试表明，该装置能有效地起阻垢、除垢、防腐蚀作用，并具有制造运动费用低、效率高、无二次污染等特点。     

直膨式太阳能热泵热水器及其热经济性分析

介绍了直膨式太阳能辅助热泵热水器(DX-SAHPWH)的基本结构和工作原理.计算了直膨式太阳能辅助热泵热水器、空气源热泵热水器、太阳能热水器、电热水器和燃气热水器的运行能耗.分析了直膨式太阳能辅助热泵热水器的市场潜力、经济性以及社会效益.几种热水器比较结果表明,直膨式太阳能辅助热泵热水器能耗最小,运行费仅为电热水器的1/3,燃气热水器的1/2,空气源热泵热水器的415;与电热水器相比,使用直膨式太阳能辅助热泵热水器,户均年运行费可减少约1500元,2年左右即可回收额外的初投资.直膨式太阳能辅助热泵热水器与空气源热泵热水器的市场价格相当.由于其节能、环保、安全等,自身优势明显,预期该热水器应用前景广阔.     

福建省太阳能热水器推广现状与发展对策

福建省地处亚热带，年平均气温在 19℃左右，夏秋季节太阳辐射最为丰富，冬季次之，春季梅雨季节太阳辐射量最少。太阳能热水器直接使用时间在 8个月左右。开发利用太阳能资源，减少城乡环境污染，提高人民生活质量，已经引起省委、省政府有关领导的高度重视，也吸引着越来越多的科技人员和工程技术人员的积极参与。 1太阳能热水器推广现状 　　从 1998年起，福建省提出以经济效益为中心，以保证质量为重点，以技术培训和网络组建为依托的工作思路，加大太阳能热水器推广工作的指导力度。目前，全省累计推广太阳能热水器近 3万 m2，分布在 9…     

Solar water heaters in China: A new day dawning

Solar thermal utilization, especially the application of solar water heater technology, has developed rapidly in China in recent decades. Manufacturing and marketing developments have been especially strong in provinces such as Zhejiang, Shandong and Jiangsu. This paper takes Zhejiang, a relatively affluent province, as a case study area to assess the performance of solar water heater utilization in China. The study will focus on institutional setting, economic and technological performance, energy performance, and environmental and social impact. Results show that China has greatly increased solar water heater utilization, which has brought China great economic, environmental and social benefits. However, China is confronted with malfeasant market competition, technical flaws in solar water heater products and social conflict concerning solar water heater installation. For further development of the solar water heater, China should clarify the compulsory installation policy and include solar water heaters into the current “Home Appliances Going to the Countryside” project; most of the widely used vacuum tube products should be replaced by flat plate products, and the technology improvement should focus on anti-freezing and water saving; the resources of solar water heater market should be consolidated and most of the OEM manufacturers should evolve to ODM and OBM enterprises.     

Performance study of forced circulation solar water heaters using packed-bed collectors

A performance study of forced circulation solar water heaters using packed-bed solar collectors is presented. Iron chips, gravel and stones have been used as packing materials. Thermal energy stored in the tank, system overall efficiency and pay-back capital for these solar water heaters are compared with those for solar water heaters using a plane collector. It is observed that the performance of the solar water heater is improved appreciably by packing its collector with packing material. A solar water heater using an iron chip, packed-bed collector shows the best performance.     

Performance study of thermosyphonic circulation solar water heaters using packed bed collectors

In the present investigation the performance behaviour of thermosyphonic circulation solar water heaters using packed bed collectors has been analysed. Iron chips, gravels and stones have been used as packing materials. Average tank water temperature, collector as well as system efficiency and mony pay-back for these packed bed solar water heaters are compared with those for solar water heater using a plane collector. Experimental results reveal that the performance of solar water heater improves appreciably by packing its collector with packing material. Among the packed-bed solar water heaters tested the iron chips packed-bed solar water heater gives the overall best performance.     

Exergy analysis of domestic-scale solar water heaters

Solar water heater is the most popular means of solar energy utilization because of technological feasibility and economic attraction compared with other kinds of solar energy utilization. Earlier assessments of domestic-scale solar water heaters were based on the first thermodynamic law. However, this kind of assessment cannot perfectly describe the performance of solar water heaters, since the essence of energy utilization is to extract available energy as much as possible. So, it is necessary to evaluate domestic-scale solar water heaters based on the second thermodynamic law.No matter the technology process, from the property of energy utilization perspective, we can separate the technology process into three intimately related sub-procedures, namely conversion procedure, utilization procedure, and recycling procedure. An energy analysis entitled ‘Three Procedure Theory’ can be conveniently conducted as presented by Professor Hua Ben. Compared with other theories of energy analysis, three procedure theory exhibits great advantages. The utilization procedure puts forth requirement for the design of parameters in conversion procedure and sets up limits in the consideration of recycling procedure. Of course, under specific conditions, the utilization procedure also receives feedback from other procedures. Three procedure theory furnishes us a good platform to perform energy analysis.The study in this paper is based on three procedure theory. Exergy analysis is conducted with the aim of providing some methods to save cost and keep the efficiency of domestic-scale solar water heater to desired extent and at the same time figuring out related exergy losses. From this survey, it is shown that for an ordinary thermally insulated domestic-scale solar water heater, D_ju (exergy losses due to imperfectly thermal insulation in collector) and D_jR (exergy losses due to imperfectly thermal insulation in storage barrel) cannot be avoided. D_ku (exergy losses due to irreversibility in collector) is mainly caused by irreversibility of heat transfer and D_kR (exergy losses due to irreversibility in storage barrel) is dominated by the mixing of water at different temperature. D_ku acts as the driving force for the system while D_kR is of little contribution. A good design of storage barrel with little D_kR will go a long way in improving exergy efficiency. An equation for computing D_kR is presented. For the collector, which is the core of the domestic-scale solar water heater, a judicious choice of width of plate W and layer number of cover is necessary. We define collector exergy efficiency η_xc to be η_xc=E_xo/E_xu. The relation between collector exergy efficiency and width of plate together with layer number of cover is also analysed.     

Experimental and theoretical studies of recyclic flat-plate solar water heaters equipped with rectangle conduits

A recycle operation design using a flat-plate solar water heater with rectangle flow conduits was theoretically and experimentally investigated. Devices with differing flow-conduit geometries (i.e. aspect ratio) and external recycle were designed to create a solar heater with low heat-transfer resistance between the absorber and working fluid to increase the convective heat-transfer coefficient. Considerable solar water heater collector efficiency improvement has been obtained employing rectangle flow conduits and a recycle operation, instead of recycle solar collector constructed with circular pipes operated at the same total mass flow rate. Under a fixed absorber area and distance between the flow conduits, the collector efficiency increases with increasing flow conduit aspect ratio, total mass flow rate and recycle ratio but with decreasing inlet water temperature. The incident solar radiation, mass flow rate, recycle ratio and flow conduit aspect ratio influences on the collector efficiency and energy consumption are also discussed.     

Energy conservation and payback periods of natural circulation type solar water heaters

Energy savings in relation to different fuels, namely firewood, coal, kerosene, LPG and electricity have been calculated for a pressurized natural circulation type solar water heater with blackboard paint and a selective surface on the absorber. The payback periods have been computed by considering 10% compound annual interest, 5% annual maintenance cost and 5% inflation per year in maintenance cost and fuel prices. The cash flow has also been worked out for both solar water heaters. The cash flow is more for a solar water heater with a selective surface. The payback periods are 2.08–8.67 years for a solar water heater with a selective surface and 2.13–8.96 years for a solar water heater with blackboard paint. The estimated life of a heater is about 15 years. This shows that use of a solar water heater for heating water is very economical.     

Performance of experimental solar water heaters in Australia

Seven experimental solar water heaters were installed at C.S.I.R.O. laboratories throughout Australia in order to gain field experience and performance data for various localities. Each heater included an insulated 70-gal hot water storage tank with a built-in electric booster and two solar absorbers of total active area of 45 sq ft.

Each morning approximately 45 gal of water at a temperature of about 135°F were discharged from the tank. Average monthly values for a 12-month period are given for the daily electric power consumption and the solar contribution. Mean yearly contribution of the solar energy under these conditions was from 60 to 80 per cent of the total energy required, depending on the district in which the heaters were located. In order to determine the extent to which the results are typical, a comparison is given, for some of the districts, of the sunshine hours recorded during the test period, with the nominal 30-year average.     

New test method for gas boosters with domestic solar water heaters

This paper describes a new test method for determining the annual energy consumption of a domestic solar water heater incorporating an in-series gas booster on the outlet of the storage vessel to provide auxiliary heating. The test method accounts for the variation in performance of the gas booster as its incoming water temperature and flow rate varies. Systems incorporating both standard and condensing gas instantaneous water heaters are evaluated. An experimental method was developed to characterize the steady-state performance of the gas booster and the resulting performance equation incorporated in a TRNSYS model of the solar water heater to assess gas consumption. Using this method, annual gas consumption is found to be 15% higher than calculated by a current standard where gas booster efficiency is held constant regardless of water flow rate or temperature. The condensing gas booster tested was found to maintain a significant performance advantage over the non-condensing model over a range of solar water heaters.     

Development of heat pipes for solar water heaters

Numerous heat pipes were designed, manufactured, and filled on a specially developed filling rig. Each heat pipe was incorporated into a prototype solar water heater developed for this purpose, and was tested under actual insolation condition. An extensive testing program lasting for more than a year revealed that the heat pipes perform satisfactorily as heat transfer elements in solar water heaters.A special heat pipe featuring a compact and effective condenser configuration was also tested. It was observed to likewise exhibit isothermal behavior and hence promised potential for large scale solar applications.     

Performance of solar water heaters with narrow mantle heat exchangers

This paper evaluates the performance of narrow-gap vertical mantle heat exchangers with a two-pass arrangement for use in pumped-circulation solar water heaters. Both measured mantle side and tank side heat transfer correlations have been developed and implemented in a TRNSYS model of a complete solar water heater incorporating this type of heat exchanger. Predictions of the annual solar contribution for mantle-tank systems are compared to direct-coupled systems. The direct-coupled systems are found to provide slightly higher annual energy saving than mantle-tank systems for standard domestic hot water demand in Australia. However, the reduction in performance is outweighed by the benefit of freeze protection provided by incorporating a collector loop heat exchanger in the system.