连接方式对自然循环太阳能热水系统的影响

以国标GB／T18708—2002《家用太阳热水系统热性能试验方法》为依据，针对自然循环平板式太阳能热水系统在连接方式不同的情况下，其热性能的差异进行了对比试验，并从自然循环系统循环动力——热虹吸压力的角度分析了两种连接方式下热性能差异的原因。     

平板式太阳能热水系统水流阻力的工程计算方法

提出了平板太阳能热水系统水流阻力的一种简易计算方法，它有杉当量长度法计算局部阻力。     

改善太阳能热水系统流量分布的研究

太阳能热水系统的流量分布不均匀严重影响其热效率,为了改善流量分布,提高效率,简要分析了自然循环和强制循环的太阳能热水系统中流量分布情况及其成因,论证了强制循环热水系统中流量分布不均匀现象普遍存在。针对该问题提出了几种使流量均匀化的措施,其中改变集热器管路中的局部阻力特性最容易实现。     

太阳能热水系统装置的效益分析

太阳能热水系统装置的效益分析北京市农村能源办公室史殿林太阳能热水系统装置主要是生产低温用热水，一般作为人们淋浴之用。那么，它的效益如何呢？我们可以用平板式太阳能热水系统装置为实例进行分析。１．系统装置效益目前，从北京市五家太阳能热水器生产企业调查，采...     

强制循环太阳能热水系统的改进

强制循环太阳能热水系统的改进江苏省太阳能研究所杨廷柱，扬汇涛，顾海燕，孙学刚，薛长松小规模的家用太阳能热水器通常采用自然循环式，而对于集体用大规模的太阳能热水系统，则须采用定温放水直流式或强制循环形式。一般强制循环太阳能热水系统如图１所示。阳光照射在...     

几种太阳能热水系统的You分析

运用热力学的热平衡和You分析原理,对几中太阳能热水系统进行了用能效率分析,得出了强制循环太阳能热水系统的热效率和You效率为提高、自然循环次之、直流式系统最低,分析了太阳能热水系统You损最大部分是因管路的散热所致,因此加强循环管理绝热保温是提高太阳能热水系统用能效率的主要途径。     

直流-自然循环复合式太阳能热水系统

分析了目前常用的各类太阳能热水系统的特点，提出了一种直流－自然循环复合式太阳能热水系统的结构，并分析了该系统的特性，认为这种系统具有广阔的应用前景。     

太阳能热水系统热性能与流动性能研究

直流式比自然循环式太阳能热水系统有许多优点,温控阀控制的直流式热水系统更具竞争力。必须重视流动性能和阻力特性对直流系统的影响。应采用热性能与流动性能相结合的方法对直流式热水系统进行评价。     

拉萨地区的太阳能热水系统

西藏自治区建筑勘察设计院从六十年代开始研究设计太阳能浴室。经过不断的努力,拉萨地区的太阳能热水系统日趋成熟,既有大型浴室,又有一家一户的小型热水器;既有自然循环热水系统,又有电控定温自动放水、手控直流放水及复合循环等热水系统,这些太阳能热水系统取得了良好的效果,受到用户的好评。     

多层建筑集中供热热管太阳能集热器系统的研究

结合建筑的大面积集中供热已成为节能降耗的新途径 ,也是太阳能热利用发展的趋势。在原有铜铝复合板的基础上 ,试制了一种结合多层建筑的集中供热热管式太阳能供热系统。克服了原有的平板式和真空管式集热系统的易炸管、易冻、结垢、单管损坏后整个系统失效等问题。利用集热板价格低的特点 ,结合多层建筑 ,充分利用楼层的集热面积 ,体现了集中供热的特点 ,其热量可以互为补充 ,得到足够的热水 ,是一种很有前途和值得推广的集热系统     

新型平板式太阳能冷热联供装置

在积累了太阳固体吸附式制冷循环研究的基础上，与现有的平板式太阳热水器制造技术紧密结合，提出了平板式太阳冷热联供循环方式，并在实验室内成功地制作了实物样机。该装置能有效地回收太阳固体吸附式制冷不中吸附床的显热及吸附热，且操作简便。实验结果有效地支持了所提出的设想，为太阳固体吸附式制冷的实用化应用打下了良好基础。     

Thermal Modelling of a Natural Convection Solar Water Heating System with a Thermal Trap Collector

A mathematical model has been developed to study the performance of a solar water heating system with a thermal trap flat plate collector and in which the flow of water between the collector and the storage tank is maintained by natural convection. An expression has also been developed for the mass flow rate in terms of known parameters. The model yields exact expressions for the temperature of water in the storage tank as a function of time in terms of collector's parameters and the solar insolation. Numerical calculations have been performed to compare the performance of the hot water heating system with a thermal trap collector with the one with an ordinary flat plate collector.     

Optimization of tank and flat-plate collector of solar water heating system for single-family households to assure economic efficiency through the TRNSYS program

Solar water heating systems are widely used in Brazil for domestic purposes in single-family households. The exploitation of the potential energy of the water from the upper tank and the thermosyphon phenomena for hot water circulation constitutes the absolute majority of the residential solar water heating systems in the country. But, these water heating systems are usually sized according to tables provided by the manufacturers, which show the number of plates required based on the size of the family and the number of hot water outlets. This sizing is based much more on intuition rather than on scientific data. For that reason, this work has developed an optimization model for water heating systems design parameters, using a numerical simulation routine, in a long-term transient regime. The optimized design gives the slope and area of the flat plate collector, which results in the minimum cost over the equipment life cycle. The computing procedure was executed considering specific characteristics of the project. A thermosyphon solar water heating system with flat-plate collector for Sao Paulo's climate was simulated. The practice of Brazilian designers and manufacturers is to recommend the maximization of the energetic gain for the winter. This paper has analyzed in economic terms if it is more attractive to increase the gain of solar energy in the winter period, with the consequence of reduction of the solar energy gain along the year, or to adopt the adequate slope, which improves the yearly solar energy gain.     

小型太阳能溴化锂吸收式空调热水供暖系统研究

针对小型太阳能吸收式空调与大型机在结构和设计方法中差别,叙述了国内外在系统小型化,结构优化,降低成本,提高效率方面所做得的研究,提出了应用中应解决的问题。     

A comparison of solar absorption air conditioning systems

A computer simulation of solar powered absorption air conditioning systems is discussed. The results of simulations of various systems composed of conventional flat plate or evacuated tube collectors, wet or dry cooling towers, lithium bromide-water or aqua-ammonia working fluids and hot water, chilled water or refrigerant storage alternatives are obtained over a common operating cycle. Performance of the lithium bromide-water working fluid is shown to be superior to aqua-ammonia. Relative performance gains realized with the evacuated tube collector and relative performance losses associated with the dry cooling tower are presented. Chilled water storage is shown to be advantageous for an evacuated collector, dry cooling tower, lithium bromide-water system.     

Domestic solar thermal water heating: A sustainable option for the UK?

This paper considers life cycle environmental sustainability of solar water heating systems in regions with low solar irradiation, such as the UK. The results suggest that flat plate collectors have slightly lower environmental impacts than evacuated tube designs. Reducing the current energy losses of 65%–45% would reduce the impacts by around 35%. Compared to a gas boiler, solar thermal systems are a better option for only five out of 11 environmental impacts considered, with global warming and depletion of fossil resources being lower by 88% and 83%, respectively. Other impacts such as human and eco-toxicity are up to 85% higher. The solar systems score better relative to electrical water heating for eight out of 11 impacts. They are also environmentally more sustainable than heat pumps for seven categories. However, their potential is hampered because they need a back-up heating system, typically gas boiler. For this reason as well as due to a lack of suitable locations and poor efficiency, the potential of solar thermal systems to contribute to a more sustainable domestic energy supply in the UK is limited.     

Experimental study on house cooling and heating with solar energy using flat plate collector

The OSE Project aims at developing the technology to utilize solar energy for heating, cooling and hot water supply on the basis of various technology for energy conservation in buildings. For the first step of this project a solar heating and cooling system with flat plate collectors and absorption refrigeration machine was installed in a house in 1974. This paper reports outlines of the system and operating results.     

Experimental studies on solar flat plate collector with internally grooved tubes using aqueous ethylene glycol

In order to cope up with the increase in energy demand and decline in fossil fuels, it has become imperative to use renewable resources efficiently. Among these renewable resources, solar thermal energy is abundant in nature. Solar water heating systems are one of the most important applications of solar thermal energy. Providing internal fins to absorber tube is the technique to improve heat transfer augmentation. Hence in the present study, experiments were performed on solar flat plate collector with different cross section of absorber tubes (plain tube and internally grooved tubes with different helix angles) and by varying the mass flow rates of the working fluids. This study reports the experimental results of flat plate collector, where the working fluid is water and aqueous ethylene glycol (50 : 50). Temperature profile of grooved absorber tube will be compared with plain tube. Since conversion efficiency of solar devices is low, the present study mainly focuses on improving the efficiency of solar flat plate collector.     

Transient analysis of parallel plate forced circulation solar water heating system

In this paper, a transient analysis of a forced circulation solar water heating system with and without heat exchangers in the collector loop and storage tank has been presented for a parallel flat plate collector. The effect of various water heating system parameters on its performance have been studied. Numerical calculations have been made for a typical cold day viz. 26 January 1980 in Delhi.     

Performance of water-in-glass evacuated tube solar water heaters

The performance of water-in-glass evacuated tube solar water heaters is evaluated using experimental measurements of optical and heat loss characteristics and a simulation model of the thermosyphon circulation in single-ended tubes. The performance of water-in-glass evacuated tube solar collector systems are compared with flat plate solar collectors in a range of locations. The performance of a typical 30 tube evacuated tube array was found to be lower than a typical 2 panel flat plate array for domestic water heating in Sydney.