太阳能热水器的市场分析

太阳能热水器未与建筑结合好,使用环境不利,电、燃气热水器的竞争和产品价格偏高、品种少是制约太阳能热水器市场需求的因素;而专业分工细化、规模经营、技术创新、政策支持,人民生活水平的提高及环保意识的加强是增加太阳能热水器市场供给的因素.预测我国太阳能热水器市场的发展趋势是市场潜力大,呈高速增长态势;市场竞争激烈,价格趋于合理,执法力度加大,市场更趋规范;国内企业通力合作,积极参与国际市场竞争.     

国内太阳能热水器市场分析

1前言在各级政府的重视下,太阳能的科研、生产和理论研究不断得到了加强和发展。太阳能热水器能可靠、方便地为居民的家庭生活提供热水,并以它的节能和无污染等优点受到越来越多用户的欢迎。据统计,山东省1997年末累计已有太阳能热水器151．86万m2,太阳房15．48万m2,太阳能温室2.1万m2,塑料大棚15．2万hm2,并一直保持高速发展的势头。2太阳能热水器同电、燃气热水器的对比现代工业提供了丰富多彩的产品,几种完全不同的产品往往可以殊途同归。太阳能热水器、电热水器、燃气热水器都可以解决洗浴用热水的问题。但是,三者在使用方便、…     

太阳能热水器开发与推广浅议

太阳能热水器的开发利用,对解决城乡家庭生活用热水,节约能源、保护环境、减少污染,发挥了重要的作用,其经济效益和社会环境效益明显。从最近中国太阳能利用研讨会上获悉,近年来我国太阳能热水器特别是真空管太阳能热水器发展非常快,每年新增用户１００多万户,去年销售近３００万ｍ２（采光面积）,居世界首位。 随着科技的发展,浙江省太阳能热水器的产品质量也有了较大的提高和改进,在整体式的基础上又生产了分体式、全自动太阳能热水器,在水箱增加电辅助加热器,实行光电互补全天候使用,电子水温、水位显示报警器在太阳能热水…     

太阳能热水器的选择和鉴别

太阳能热水器的选择和鉴别黄鸣１类型（１）闷晒式由一个装有吸热水箱和玻璃盖板的保温盒和支架组成，是太阳能热水器的初级形式，结构简单，成本低廉（数百元／台），在华北地区每年可用半年左右，缺点是保温性能较差。（２）平板式由平板式集热器、蓄水箱、循环管和支架...     

槽式和塔式太阳能热发电的热效率及环境影响分析与评价

选取槽式和塔式两种太阳能热发电系统为研究对象,运用生命周期方法（Life Cycle Assessment,LCA）分别对槽式和塔式太阳能热发电进行系统、全面的环境影响评价。主要对两种太阳能热发电的用材、生产和运输3个阶段进行分析,分别计算了3个阶段的单位能耗和环境影响,并对两个系统的分析结果进行比较。同时,采用朗肯循环对两种系统进行了热效率方面的比较。     

太阳能热水器的前景

1 太阳能是21世纪的重要能源世界能源经历了柴草、煤炭、石油三个历史时期。1973年中东战争和1979年石油危机,促使了世界能源结构的变化,加快了新能源开发利用进程。21世纪太阳能将逐步代替常规能源,其成本与常规能源相当,甚至更为低廉。到21世纪末,预计太阳能将占世界能源总需要量的30%左右,同时将形成一个庞大的太阳能产业,其规模将超过目前的一些支柱产业。我国地处北半球欧亚大陆的东部,幅员辽阔,约有2/3以上的面积处于太阳能资源丰富区,我国各地太阳辐射总量为5.9×106[LCG.hqgro1]kJ/(m2·a)［140 kcal/(cm2·a)］。…     

家用太阳热水器与太阳热水系统的技术经济比较

分析了户用太阳热水器和太阳热水系统工程的经济技术特点,对两者成本构成、项目财务净现值、投入回收期和财务内部收益率等有关指标进行了经济技术比较.分析比较表明,太阳热水系统与家用热水器相比,节省安装占地,与建筑相结合得好,在降低成本,缩短投资回收期,提高经济效益方面有明显的优势.     

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.     

Thermal performance, economic and environmental life cycle analysis of thermosiphon solar water heaters

In this paper, the environmental benefits or renewable energy systems are initially presented followed by a study of the thermal performance, economics and environmental protection offered by thermosiphon solar water heating systems. The system investigated is of the domestic size, suitable to satisfy most of the hot water needs of a family of four persons. The results presented in this paper show that considerable percentage of the hot water needs of the family are covered with solar energy. This is expressed as the solar contribution and its annual value is 79%. Additionally, the system investigated give positive and very promising financial characteristics with payback time of 2.7 years and life cycle savings of 2240 € with electricity backup and payback time of 4.5 years and life cycle savings of 1056 € with diesel backup. From the results it can also be shown that by using solar energy considerable amounts of greenhouse polluting gasses are avoided. The saving, compared to a conventional system, is about 70% for electricity or diesel backup. With respect to life cycle assessment of the systems, the energy spent for the manufacture and installation of the solar systems is recouped in about 13 months, whereas the payback time with respect to emissions produced from the embodied energy required for the manufacture and installation of the systems varies from a few months to 3.2 years according to the fuel and the particular pollutant considered. It can therefore be concluded that thermosiphon solar water hearting systems offer significant protection to the environment and should be employed whenever possible in order to achieve a sustainable future.     

Simulation and experimental investigation of two hybrid solar domestic water heaters with drain water heat recovery

In this paper, the performance of two solar domestic hot waters (SDHW) with drain water heat recovery (DWHR) units is investigated. Both SDHW systems are recently installed at the Archetype Sustainable Twin Houses at Kortright Center, Vaughan, Ontario. The first SDWH system in House A consists of a flat plate solar thermal collector in combination with a gas boiler and a DWHR unit. The second SDHW system in House B includes an evacuated tube solar collector, an electric tank, and a DWHR unit. Both systems are modeled in TRNSYS, and the models are validated by experimental data. The addition of the DWHR and the flat‐plate solar thermal collector would result in 1831 kWh of annual energy saving in House A. While the addition of the DWHR and the evacuated tube collector in House B would result in an annual energy saving of 1771 kWh. Subsequently, the models are used to investigate the performance of similar systems for five major Canadian cities of Halifax, Montreal, Toronto, Edmonton, and Vancouver. The conjunctions of solar thermal collectors with DWHR units are found most beneficial in Edmonton. It is also noted from experimental and simulated results that flat‐plate solar collector‐based water heater produced more thermal energy than the system based on the evacuated tube solar collector for all major Canadian cities. Copyright © 2015 John Wiley & Sons, Ltd.     

Capital cost and economic viability of thermosyphonic solar water heaters manufactured from alternate materials in India

Many companies in India manufacture solar water heaters but these are not becoming popular in the domestic sector because of their high cost. The Ministry of Non-Conventional Energy Sources (MNES), New Delhi is recommending flat-plate collectors with copper (Cu) risers, headers and plate. Therefore, their cost is high. Long term studies have been carried out at the Central Arid Zone Research Institute, Jodhpur, to reduce the cost by replacing copper tubes with galvanised steel (G.S.) tube and copper plate with aluminium (Al) plate. The aluminium plate is wrapped over the G.S. tube by a special wire wound technique so that good contact of plate with risers and headers has been maintained. In this paper performance and testing of solar water heaters having G.S.–Al fin, Cu–Al fin and Cu–Cu fin in flat-plate collectors have been compared. It has been found that performance of all the three heaters is almost similar. The heater can provide 100 litres of hot water at an average temperature 62.0°C at 4 pm that can be retained to 50.4°C when average tap water temperature was 23.9°C. The efficiency of the heater is 51.9%. The cost of the heater with G.S.–Al collector is only Rs. 8,000.00 while it is Rs. 10,250.00 for solar water heaters with Cu–Cu collectors. The payback period of a solar water heater with G.S.–Al collector has been worked out by considering 10% compound annual interest, 5% maintenance cost, 5%, inflation in fuel prices and maintenance cost. The payback period varies between 2.92 years to 4.53 years depending upon which fuel it replaces. The payback periods are in increasing order with respect to fuels: electricity, firewood, LPG, charcoal, and kerosene.     

分体式家用太阳热水器

指出了传统太阳热水器存在的一些问题,为克服太阳热水器在高层建筑应用中受到的限制,研制了 一种靠重力循环的分体式家用太阳热水器。在冬季,用集中供暖系统中的热水为辅助热源加热蓄热水箱中的 水,以解决仅利用太阳能加热供水温度太低的问题,与利用辅助电加热相比,可降低运行费用。     

Some aspects concerning modelling the flow and heat transfer in horizontal mantle heat exchangers in solar water heaters

An experimental and numerical investigation has been undertaken to study the heat transfer process in horizontal mantle heat exchangers used in solar water heaters. A rectangular cavity has been used as a simplified geometry. With the aid of particle image velocimetry (PIV) the flow field in the centre‐plane of the rectangular cavity has been visualized. Three‐dimensional flow simulations were performed using a commercial CFD package. The impinging jet formed by the inlet flow directed towards the opposite wall was found to produce localised turbulence in the cavity, with an inlet Reynolds number as low as 360. This turbulence was found to effect the flow field and heat transfer in the cavity when the inlet Reynolds number was above 1200. It is shown that, with the boundary conditions used in this study, most of the heat transferred was in the bottom half of the cavity. This is not the ideal situation for optimization of solar water heating systems. Copyright © 1999 John Wiley & Sons, Ltd.     

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.     

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.     

Refrigerant-charged integrated solar water heater

The performance of two R-11-charged integrated solar water heater collectors was investigated experimentally for forced and natural circulation water flows. The heat transfer from the refrigerant loop to the hot water storage tank took place through a condenser of novel design integrated within the collector frame. The effect of the condenser inclination on the system efficiency was remarkable for natural circulation water flow but had no significant effect for forced circulation flow. The difference in thermal response between the refrigerant and water loops caused buildup of stored energy in the condenser. This energy affected the buoyancy forces and generated flow pulsation that caused a harmonic-like variation of the system efficiency. This effect vanished with forced water circulation flow. The system efficiency varied between 20 and 50% depending on the solar insolation.