太阳池的研究与应用

自从1902年Kalecsinsky首次发现了天然太阳池现象以后，经过长期的研究和发展，太阳池技术已被广泛应用于发电、取暖、海水淡化．矿物加工等领域，太阳池成为近期内进行大规模太阳能热利用的最有前景的低温热源装置。主要综述了太阳池的集热原理及建造方法、太阳池中热量的贮存及提取方式、太阳池的应用以及研究动向等，并指出目前我国太阳池技术还处于实验研究的阶段，而我国具有丰富的太阳能和盐资源，大力开发太阳池技术将为发展地方经济起到重要的作用。     

多孔介质对太阳池传热传质影响的研究

通过实验与数值模拟相结合的方法研究在太阳池底部增设多孔介质水层对太阳池热盐双扩散及储热量、稳定性等的影响.在实验室研究了多孔介质对盐扩散的抑制作用.在海边沙滩建造了两个小型太阳池,测量了有无多孔介质太阳池的温度分布和盐度分布并进行数值模拟,模拟值与实验值吻合较好.计算了有无多孔介质太阳池盐梯度的分布、池子稳定性情况以及多孔介质对太阳池的储热量的影响.结果表明,在太阳池底部加设多孔介质水层可以提高太阳池LCZ温度.多孔介质水层有利于提高太阳池的储热量,有利于抑制盐分向上扩散,可以节省太阳池的盐资源消耗,并有利于提高非对流层的盐梯度和稳定性.     

芒硝太阳池的研究与应用

该本对芒硝太阳池梯度区的浓度分布、温度分布以及芒硝太阳池的能量利用和应用进行了研究，并与实验结果进行比较，两者基本吻合，研究认为芒硝太阳池梯度区(非对流层)内温度分布，浓度分布是非线形的，利用太阳池技术为开发芒硝资源提供了一种新技术。     

纳米颗粒对盐梯度太阳池热性能影响的实验研究

为了增强太阳池的储热温度以及热效率,采用了在太阳池下对流层添加纳米颗粒的方法.通过光照实验与沉降实验选取质量分数为0.010％的碳纳米管溶液添加到太阳池的下对流层,然后与普通盐梯度太阳池进行对比实验,并对实验数据进行分析、计算.实验结果表明:在相同模拟光源下,含纳米颗粒小型太阳池的下对流层平均温度提高了 1.7℃,效率...     

微型太阳池不同盖层的对比实验研究

设计和建造了四个大小、形状及保温条件相同的微型实验性太阳池,通过对比对影响太阳池性能的若干因素进行了研究,为实用性太阳池的建造准备了条件,并为完善太阳池的理论模型提供了实验数据。此外,本文还分析了四种不同盖层太阳池的实验结果,计算了微型池内的Soret效应和Dufour效应的影响,并提出了相应的建议。     

我国大陆地区建造太阳池的区划模型

分析与太阳池建造、运行有关的相关因素，从太阳辐射资源、盐资源、气候状况以及地下水文地质状况等自然条件考虑，分别讨论它们对建池及运行的影响，并确定建造太阳区划的分类指标。在此基础上收集有关资料和数据，运用模糊数学方法，对我国建造太阳池的自然条件作了定量的综合分析研究，进而提出我国建造太阳池的区划模型，并一一作出评价，指出我国大陆适宜建造太阳池的区域。     

太阳池热能利用技术

回顾了太阳池的发展历史,介绍了太阳池的结构和工作原理,论述了从太阳池中提取热量的方法及太阳池的应用.太阳池发电可为不发达地区提供部分电能,是一种很有竞争力和发展前景的太阳能收集和储存系统.     

不同浊度分布下太阳池热性能模拟

通过实验验证了太阳池辐射透射模型(Wang and Seyed-Yagoobi model)在小浊度范围内的准确性,从光学和热力学角度分析了非均匀浊度下太阳池的辐射透射率,并模拟了不同浊度分布状况下太阳池储热层的温度及各层的热效率。当池水浊度在垂直方向上的平均浊度相同时,浊度分布自上而下线性递增情况时太阳池下对流层的辐射透射率、温度、热效率均高于浊度均匀分布和池水浊度分布自上而下线性递减两种情况。根据研究,指出了太阳池要着重控制上对流层和非对流层的浊度,而对于下对流层的浊度则不必重点处理。另外,对于实际的太阳池采取实验手段预防降雨对太阳池浊度产生的影响。     

在盐梯度太阳池储热层添加锅炉渣的实验和理论研究

提出在太阳池储热层添加锅炉渣从而增加太阳池储热层温度的方法,并从实验上加以验证.为此,采用小塑料槽模拟太阳池进行了不同添加材料效果比较的小规模实验.在小型实验的基础上,在表面积2.3m×2.8m,深0.8m的实验太阳池储热层底部添加0.1m厚的锅炉渣,进行为期28d的测定,以实际测定的太阳辐射强度和环境温度作为边界条件模拟计算,并将实验结果与计算结果作了比较,二者吻合较好.实验结果表明在太阳池底部添加0.1m锅炉渣比不添加情况下太阳池底部(距底面0.2m以下)平均温度的计算值要高8.5℃.该方法造价低,易实现,适合用于增加大型太阳池储热层温度的实际应用.     

小型太阳池瞬态传热传质

该文从实验和数值上调查了小型太阳池的瞬态传热传质问题.计算中考虑侧墙的阴影作用和本地的气候条件,二维导热模型和沿深度方向的一维盐扩散模型给出了长期运行小型太阳池内的温度和盐度发展情况.在大连沿海建立2.3m×2.8m,深0.8m实验太阳池,采用卤水和海水灌注太阳池,进行了连续60d的实验测定.小型海水太刚池实验数据用于检验计算结果.计算结果表明,从5月1日开始运行至7月中下旬,储热层平均温度达到近65℃的最大值.实验值与计算值较好吻合.盐度扩散的实验和计算结果表明这种海水一卤水灌注的太阳池中盐度的扩散要比一般的盐水池(NaCl溶液)更为缓慢.     

Dependence of sound velocity on salinity and temperature in saline solutions

An ultrasonic velocimeter has previously been developed and tested for the measurement of salinity distributions in salt-gradient solar ponds. The results of the previous study were salinity relations for NaCl solutions as a function of speed of sound and temperature over the salinity and temperature ranges commonly encountered in solar ponds. The present work develops similar relations for several other common single salt solutions. Also, a general relationship which gives the change in sound speed as a function of salinity and temperature for a mixture of salts is developed. This relation allows the prediction of salinity as a function of speed of sound and temperature in any solar pond based only on the composition of salts in the pond and the individual constituent salt calibration relations. The present results show that the general relation accurately predicts sound speed behavior in bittern solutions. Extension of the results to mixtures with large fractions of constituent salts has yet to be demonstrated.     

Introduction of a passive method for salt replenishment in the operation of solar ponds

A passive method for the replenishment of salt in solar ponds is suggested, based on the natural circulation of water caused by density differences. Water, from a selected depth in the solar pond, is passed through a salt bed in an adjacent tank, where its salinity is increased before it is returned to the bottom region of the solar pond. The difference between the densities, at the points of intake and outlet, provide the driving force for the natural circulation. Careful system design ensures that this circulation will transport enough salt to the bottom region of the pond to compensate for its upward diffusion in salt gradient solar ponds. This method negates the need for the pumping installation normally required for salt replenishment; and it provides a simple, self-regulating, and reliable method for density control in the bottom region of solar ponds.     

Examining potential benefits of combining a chimney with a salinity gradient solar pond for production of power in salt affected areas

The concept of combining a salinity gradient solar pond with a chimney to produce power in salt affected areas is examined. Firstly the causes of salinity in salt affected areas of northern Victoria, Australia are discussed. Existing salinity mitigation schemes are introduced and the integration of solar ponds with those schemes is discussed. Later it is shown how a solar pond can be combined with a chimney incorporating an air turbine for the production of power. Following the introduction of this concept the preliminary design is presented for a demonstration power plant incorporating a solar pond of area 6 hectares and depth 3 m with a 200 m tall chimney of 10 m diameter. The performance, including output power and efficiency of the proposed plant operating in northern Victoria is analysed and the results are discussed. The paper also discusses the overall advantages of using a solar pond with a chimney for production of power including the use of the large thermal mass of a solar pond as a practical and efficient method of storing collected solar energy.     

Thermal analysis and measurement of a solar pond prototype to study the non-convective zone salt gradient stability

Solar ponds combine solar energy collection with long-term storage and can provide reliable thermal energy at temperature ranges from 50 to 90 °C. A solar pond consists of three distinct zones. The first zone, which is located at the top of the pond and contains the less dense saltwater mixture, is the absorption and transmission region, also known as the upper convective zone (UCZ). The second zone, which contains a variation of saltwater densities increasing with depth, is the gradient zone or non-convective zone (NCZ). The last zone is the storage zone or lower convective zone (LCZ). In this region, the density is uniform and near saturation. The stability of a solar pond prototype was experimentally performed. The setup is composed of an acrylic tube with a hot plate emulating the solar thermal energy input. A study of various salinity gradients was performed based on the Stability Margin Number (SMN) criterion, which is used to satisfy the dynamic stability criterion. It was observed that erosion of the NCZ was accelerated due to mass diffusion and convection in the LCZ. It can be determined that for this prototype the density of the NCZ is greatly affected as the SMN reaches 1.5.     

Theoretical and experimental comparison of conventional and advanced solar pond performance

Numerical and physical experiments were carried out to compare the performance of two solar pond systems: (a) a conventional salt gradient solar pond (CSP) and (b) a salt gradient pond operated as an “advanced solar pond” (ASP). The main differences in the ASP, as originally proposed by Osdor[1], are an increase in overall salinity and the introduction of a stratified flowing layer near the bottom of the gradient zone. The increased salinity is meant to reduce evaporative heat loss and make up water requirements, while the additional flowing layer allows extra heat extraction and possibly higher temperatures to develop in the lower convective zone. A numerical study was performed to evaluate the salinity effect and the results show only a minor effect of increased salinity on heat collection efficiency. However, slightly higher collection temperatures are obtained, which may provide some benefit for heat engine efficiency. Physical experiments were performed to test the feasibility of constructing and maintaining the necessary flow system for the ASP and also to compare the performance of the ASP and the CSP under similar laboratory conditions. These tests showed that a stable stratified flowing layer could be maintained and that the ASP configuration produced higher efficiencies.     

Modeling the performance of a solar pond as a source of thermal energy

The use of solar ponds is becoming more attractive in today's energy scene. A major advantage of solar ponds over other collectors is the ability to store thermal energy for long periods of time. The solar pond comprises a hydraulic system subject to processes of heat and mass transfer. The design of this system and the related equipment requires a thorough knowledge of the pond heating-up process and expected thermohaline structure within the pond. The current study considers that convection currents in the pond are inhibited by the salinity distribution, and applies a finite difference implicit model in order to investigate the interaction among physical variables represented by various dimensionless parameters. Variables which are included in the analysis comprise the solar radiation input and absorption as it passes through the pond; diffusion and dispersion of heat within the pond; absorption of heat at the bottom of the pond; and withdrawal of heat from layers within the pond. The physical variables generate 3 dimensionless variables associated with the pond's heating-up process. A 4 dimensionless variable is associated with the heat utilization. The analysis represented in this paper concerns the interaction between these dimensionless parameters and its implications.     

Solar pond modeling with density and viscosity dependent on temperature and salinity

The paper presents a 2D numerical model where the behavior of a salt gradient solar pond (SGSP) is described in terms of temperature, salt concentration and velocity with the fluid density and viscosity dependent on temperature and salt concentration. The discretization of the governing equations is based on the respective weak formulations. The rectangular geometry allows for spectral type Galerkin approximations for which the essential homogeneous boundary conditions can easily be imposed. Taking into account the variation of density and viscosity with temperature and salinity improved the agreement between the numerical and the experimental results.     

Control of a solar pond

Solar ponds hold the promise of providing an alternative to diesel generation of electricity at remote locations in Australia where fuel costs are high. However, to reliably generate electricity with a solar pond requires high temperatures to be maintained throughout the year; this goal had eluded the Alice Springs solar pond prior to 1989 because of double-diffusive convection within the gradient zone. This paper presents control strategies designed to provide successful high temperature operation of a solar pond year-round. The strategies, which consist mainly of manipulating upper surface layer salinity and extracting heat from the storage zone are well suited to automation. They were tested at the Alice Springs solar pond during the summer of 1989 and maintained temperatures in excess of 85°C for several months without any gradient stability problems.     

Fertilizer solar ponds as a clean source of energy: Some observations from small scale experiments

Commercially available NH₂CONH₂ is used to establish a salinity gradient solar pond in a small 1 m² outdoor tank. With a salinity difference of 35% between the upper and lower zone, a temperature difference of 23°C was obtained without any instabilities in the gradient zone. The difference in concentration of solution required to sustain a temperature difference of 40°C across the gradient zone is 520 kg/m³. By economically using runoff into the fertilizer cycle of an agricultural system the estimated cost of fertilizer solar pond generated heat is Rs. 1.10/kWh.     

超声波法测量盐水溶液浓度

利用超声波在不同浓度、不同温度的盐水溶液中传播速度不同这一特性，测出盐浓度Ｓ、声速Ｖ和温度Ｔ之间的关系，绘制不同温度下的Ｓ－Ｖ曲线和不同浓度下的Ｖ－Ｔ曲线，用计算机对实验曲线进行拟合，给出相应的多项式回归方程，模拟计算结果十分接近实验结果，该方法测试简便，精确度高。