太阳能热气流电站透平布置位置研究

基于相对压力概念，建立了太阳能热气流电站系统的新数学模型，并通过数值模拟得到系统内的相对压力分布。根据系统相对压力的分布特点确定了透平布置的最佳位置：在烟囱的底部区域，相对压力最小，压力梯度最大，最适于布置透平；在技术容许的情况下，为实现能量转换效率最高，不宜采用能量梯级利用方案。     

基于烟囱内部材料性能和烟气腐蚀性的烟囱腐蚀评估

火电厂的烟囱不同程度地存在着腐蚀的问题,这不仅直接威胁烟囱的使用寿命,而且还影响电厂的安全运行.将基于烟囱内部材料的性能,烟气的腐蚀性以及烟囱内正压出现与否来对火电厂烟囱腐蚀发生的程度进行评估,为火电厂烟囱防腐工作的开展提供一定的参考.     

喷嘴位置对新型水煤浆气化炉内流场的影响

为了考察气化炉炉侧喷嘴入射角对炉内流场分布、压力分布和颗粒浓度分布的影响，对一种600kg／h的新型水煤浆气化炉炉内三维流场进行了冷态数值模拟。结果表明，喷嘴距气化炉顶部0．9m时，气化炉炉内流场分布最合理，压力分布和颗粒浓度分布最均匀。分析结果为气化炉的设计和运行提供了参考。     

核设施排风主烟囱退役去污通风模拟分析

核设施排风烟囱在核设施运行的过程中,不可避免地受到放射性污染。针对外部为混凝土结构的放射性污染烟囱拆除时的通风系统,采用CFD模拟仿真的方法,通过改变通风出口风速及出口高度,对烟囱拆除时的内部气流组织及压力的影响因素进行分析。结果表明:通过抬高1 m或降低1 m的退役烟囱出风口标高对通风时的烟囱内部气流组织及压力影响甚微;每改变2 m/s的出口风速,可以使烟囱顶部的负压升高或降低约20 Pa,并能显著改变烟囱内部的旋涡流场。此结果可为放射性污染混凝土烟囱退役工程方案奠定科学的理论基础。     

隧道式烟囱太阳热风发电系统

太阳热风发电系统的基本原理如图1所示，由3个主要部件构成：底部为太阳能空气加热器（集热棚），中间为太阳能烟囱，烟囱底部布置风力发电机组。太阳辐射加热玻璃屋顶下温室内的空气，致使热空气源源不断流向位于温室中央的太阳能烟囱；烟囱两端空气的温差和压差导致空气沿太阳能烟囱上升产生动能，在烟囱内安装风力透平发电机，产生电能，风最后从烟囱顶部排入大气。其能量流向为太阳光能先变成空气的热能，再转变为风的动能，再转变为风力透平的动能，最后得到电能。     

椭圆滑动轴承椭圆度对汽轮机振动的影响

用三维软件UG建立椭圆轴承物理模型,将建立的模型导入ANSYS软件进行分析,首先运用CFD模块计算不同椭圆度圆柱滑动轴承的压力分布,后将所得的压力分布导入ANSYS软件里进行多物理场耦合分析,分析不同椭圆度下的油膜特性和其轴承的振动幅值.数值计算结果表明:汽轮机运行中存在合理椭圆度范围,使得汽轮机的振动幅值在允许值内.     

杂质和缺陷对铸造多晶硅寿命分布的影响

铸造多晶硅的原生少子寿命沿晶锭生长方向呈倒U字型分布,对应于硅锭体内缺陷和主要杂质的规律性分布.硅锭中部Fe浓度低,微缺陷较少,对应的体寿命相对较高.硅锭底部高浓度的O、Fe杂质及高密度微缺陷导致了该区域体寿命偏低;硅锭顶部存在高浓度的C、Fe杂质及大量微缺陷,尤其是高密度位错与铁的相互作用导致该区域体寿命偏低.大量沉淀和结构缺陷并存使得晶锭底部和顶部的材料难以通过吸杂和钝化来改善少子寿命.     

依托高楼的太阳能热气流电站系统的CFD模拟

设计了一种依托高楼的太阳能热气流电站,建立了相应的数学模型。利用Fluent软件对该系统的流场及温度场进行了数值模拟,并对电站结构进行了优化设计。模拟结果表明:随着烟囱高度的增加,烟囱内气流的温度不断上升,在出口处由于回流的影响温度稍有下降,气流速度不断增大,气流的压力分布先减小后增加。由于平板集热器的加热作用使烟囱内气流的温度分布不均匀,设计中可将平板型储热器换为带有肋片扩展表面的储热器,并对烟囱与扩压管联接处采用流线形联接进行过渡,以减少此处的流动阻力。同时,设计一个收缩型的烟囱出口,以保证电站系统产生较大的抽力,从而提高电站系统的能量转换率。     

太阳能烟囱发电装置的CFD模拟

用Fluent软件对太阳能烟囱发电装置内的气流进行了数值模拟，获得了太阳能烟囱发电装置内气流流速、温度等分布，并将温度场模拟计算值和试验检测值进行了比较。结果表明：气流在集热棚中从四周向中部汇流是一个加速的过程；从地面到烟囱，随着高度的增加温度呈递减分布。温度分布模拟与试验检测结果的规律基本相似。但由于进行了稳态假设，也存在一定差别。数值模拟结果以集热棚中心呈对称分布。然而，由于集热棚南部接收的太阳辐射大于北部，在试验检测中南边的温度明显高于北边的温度，温度的峰值向南边偏移，呈不对称分布。     

排放湿烟气烟囱的钢内筒设计有关问题探讨

针对湿式石灰石-石膏法脱硫工艺取消烟气加热装置后排烟参数的急剧变化对烟囱设计的影响问题，通过对某电厂三期工程钢烟囱的设计实践，对排放湿烟气烟囱的钢内筒设计有关问题进行探讨。结论是湿法脱硫工艺在取消烟气加热装置后对烟囱设计的影响十分复杂，应加强烟囱设计中环保、土建、热机专业的设计协调，设计时应针对采用不同的烟囱内衬工艺，核算烟囱的内径、流速、沿程阻力是否满足烟囱的安全可靠运行。     

Feasibility study of a solar chimney power plant in Jordan

A solar chimney power plant system is theoretically designed for future erection in Jordan. Analytical analysis of the system is simulated by mathematical software. The actual values of solar irradiation in Jordan are used in the simulation to predict the power output of the solar chimney power plant. The output results of the maximum (inlet) values of velocity, pressure, and mass flow rate of air versus the chimney height variation are obtained. Furthermore, the electrical power output and the efficiency of chimney versus chimney height variation were determined. For a solar collector diameter of 40 m and a chimney diameter of 3.5 m, the maximum power output (85 kW) was obtained for a chimney height of 210 m.     

Analysis of a solar chimney power plant in the Arabian Gulf region

A simplified thermodynamics analytical model for steady airflow inside a solar chimney is performed. A simplified Bernoulli equation combined with fluid statics and ideal gas equation was implemented and solved using EES solver to predict the performance of the solar chimney power plant. The analytical model matched the experimental data and numerical study available in the literature. The developed analytical model was used to evaluate the effect of geometric parameters on the solar plant power generation. The analysis showed that chimney height and turbine pressure head are the most important physical variables for the solar chimney design. The study showed that second-law efficiency has non-monotonic relation with turbine pressure head. The model shows that second-law efficiency and power harvested increase with the increase of chimney height and/or diameter. The developed model is used to analyze the feasibility of solar chimney power plants for the UAE climate which possesses typical characteristics of the Gulf climate. The solar characteristics of the UAE are shown along with characteristic meteorological data. A solar chimney power plant with a chimney height of 500 m and a collector roof diameter of 1000 m would produce at least 8 MW of power. The amount of power produced during the summer would be higher where the demand in the Gulf area is the highest.     

烟囱性状对太阳能烟囱发电系统效率的影响

采用计算流体动力学（CFD）方法分析了烟囱对太阳能烟囱发电系统效率的影响。通过对烟囱高度、烟囱形状、烟囱内表面粗糙度和温度对系统的影响分析表明：在其它条件不变的情况下，烟囱高度和直径对系统效率影响最为显著，其次是形状，最后是烟囱内表面粗糙度和温度。     

Evaluation of operational control strategies applicable to solar chimney power plants

Numerical simulations are carried out to study the performance of two schemes of power output control applicable to solar chimney power plants. Either the volume flow or the turbine pressure drop is used as independent control variable. Values found in the literature for the optimum ratio of turbine pressure drop to pressure potential vary between 2/3 and 0.97. It is shown that the optimum ratio is not constant during the whole day and it is dependent of the heat transfer coefficients applied to the collector. This study is a contribution towards understanding solar chimney power plant performance and control and may be useful in the design of solar chimney turbines.     

Modeling and numerical simulation of solar chimney power plants

The solar chimney power plant is a simple solar thermal power plant that is capable of converting solar energy into thermal energy in the solar collector. In the second stage, the generated thermal energy is converted into kinetic energy in the chimney and ultimately into electric energy using a combination of a wind turbine and a generator. The purpose of this study is to conduct a more detailed numerical analysis of a solar chimney power plant. A mathematical model based on the Navier-Stokes, continuity and energy equations was developed to describe the solar chimney power plant mechanism in detail. Two different numerical simulations were performed for the geometry of the prototype in Manzanares, Spain. First, the governing equations were solved numerically using an iterative technique. Then, the numerical simulation was performed using the CFD software FLUENT that can simulate a two-dimensional axisymmetric model of a solar chimney power plant with the standard k-epsilon turbulence model. Both the predictions were compared with the available experimental data to assess the validity of the model. The temperature, velocity and pressure distributions in the solar collector are illustrated for three different solar radiations. Reasonably good quantitative agreement was obtained between the experimental data of the Manzanares prototype and both the numerical results.     

Constructal solar chimney configuration

In this study, we describe the constructal-theory search for the geometry of a solar chimney. The objective is to increase the power production over the area occupied by the plant. The ratio height/radius, maximum mass flow rate and maximum power under the constraints of a fixed area and volume are determined. We find that the power generated per unit of land area is proportional to the length scale of the power plant. The analysis is validated by a detailed mathematical model. Pressure losses are reported in terms of the dimensionless length scale of the system, and are illustrated graphically. They indicate that the pressure drop at the collector inlet and at the transition section between the collector and chimney are negligible, and the friction loss in the collector can be neglected when the svelteness (Sv) of the entire flow architecture is greater than approximately 6.     

Maximum fluid power condition in solar chimney power plants – An analytical approach

Main features of a solar chimney power plant are a circular greenhouse type collector and a tall chimney at its centre. Air flowing radially inwards under the collector roof heats up and enters the chimney after passing through a turbo-generator.The objective of the study was to investigate analytically the validity and applicability of the assumption that, for maximum fluid power, the optimum ratio of turbine pressure drop to pressure potential (available system pressure difference) is 2/3. An initial power law model assumes that pressure potential is proportional to volume flow to the power m, where m is typically a negative number between 0 and −1, and that the system pressure drop is proportional to the power n, where typically n = 2. The analysis shows that the optimum turbine pressure drop as fraction of the pressure potential is (n − m)/(n + 1), which is equal to 2/3 only when m = 0, implying a constant pressure potential, independent of flow rate. Consideration of a basic collector model proposed by Schlaich leads to the conclusion that the value of m is equal to the negative of the collector floor-to-exit efficiency. A more comprehensive optimization scheme, incorporating the basic collector model of Schlaich in the analysis, shows that the power law approach is sound and conservative.It is shown that the constant pressure potential assumption (m = 0) may lead to appreciable underestimation of the performance of a solar chimney power plant, when compared to the analyses presented in the paper. More important is that both these analyses predict that maximum fluid power is available at much lower flow rate and much higher turbine pressure drop than predicted by the constant pressure potential assumption. Thus, the constant pressure potential assumption may lead to overestimating the size of the flow passages in the plant, and designing a turbine with inadequate stall margin and excessive runaway speed margin. The derived equations may be useful in the initial estimation of plant performance, in plant performance analysis and in control algorithm design. The analyses may also serve to set up test cases for more comprehensive plant models.     

Analytical and numerical investigation of the solar chimney power plant systems

There is a surge in the use of the solar chimney power plant in the recent years which accomplishes the task of converting solar energy into kinetic energy. As the existing models are insufficient to accurately describe the mechanism, a more comprehensive model is advanced in this paper to evaluate the performance of a solar chimney power plant system, in which the effects of various parameters on the relative static pressure, driving force, power output and efficiency have been further investigated. Using the solar chimney prototype in Manzanares, Spain, as a practical example, the numerical studies are performed to explore the geometric modifications on the system performance, which show reasonable agreement with the analytical model. Copyright © 2005 John Wiley & Sons, Ltd.