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.     

相变蓄热材料应用于盐梯度太阳池的研究进展

传统盐梯度太阳池(以下简称太阳池)利用盐水的显热蓄热,导致太阳池蓄热密度低,太阳池温度的昼夜变化大,并且受提热影响明显,高温及提热不足情况下,容易导致梯度层失去稳定性.石蜡等低温相变蓄热材料应用于太阳池有利于解决上述问题,文中论述了相变蓄热材料添加到太阳池中的研究现状及发展趋势.     

配合集热器的盐梯度太阳池热性能实验与分析

构建表面积为1.50 m×1.50 m的小型实验用盐梯度太阳池,并与平板太阳能集热器配合使用,分别对普通太阳池和集热增强型太阳池进行了储热、放热实验。实验研究与理论分析表明:单独盐梯度太阳池的放热量为3.5×103k J,热效率为13.6%;集热增强型太阳池放热量可以达到4.8×103k J,且热效率增至28.1%。另外后者下对流层温度最高可提升10℃以上,从而证明太阳能集热器可以有效提高太阳池热效率,增加下对流层储热量。此外,考虑了放热过程换热器对太阳池下对流层的扰动,对比实验前后的溶液浓度,可以看出实验后太阳池盐度曲线合理,非对流层呈良好梯度分布,太阳池稳定性并未遭到破坏。     

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。     

电导法测量太阳池盐浓度分布的实验研究

对太阳池溶液浓度与电导的关系做了初步的实验测量和理论说明，并与用光学折射率法和比重计法测得的浓度做了比较。试图找出一种更为简便的太阳池盐浓度分布的测定方法。     

不同非对流层盐梯度层层数对太阳池性能影响

研究不同非对流层层数对太阳池稳定性、热性能的影响,以实现太阳池性能的优化。以工业NaCl为工质配制不同盐度溶液制备太阳池。以浊度、盐度和温度为考核指标,对太阳池的稳定性、吸热性和储热性进行研究。结果表明:当上对流层、非对流层、下对流层所占太阳池池体体积比率不变,非对流层各层厚度均匀设置时,太阳池降浊速度、盐梯度层稳定性、热性能均随太阳池非对流层盐梯度层层数的增加而增加。增加非对流层盐梯度层层数有利于改善太阳池的性能,太阳池的最佳非对流层盐梯度层层数为4。     

利用太阳池加热沼气池的实验研究

本文报道了利用小型实验性太阳池加热沼气池使之提高产气率的实验研究结果。所用太阳池的面积为11.5m~2,深度为1.2m,沼气池的容积为0.8m~3。文中还介绍了太阳池和供热系统的建造、换热器和测试元件的安装以及各个部分的运行情况,并给出了太阳池的盐水溶液温度和浓度的分布、变化以及沼气池升温和产气率提高的情况。     

四种太阳电池工质的浓度与折射率和温度的关系

选取可用作太阳池工质的ＮａＣｌ，ＣａＣｌ２、ＭｇＣｌ２和Ｎａ２ＣＯ３四种水溶液，对浓度Ｓ－折射率ｎ－温度Ｔ之间的关系进行测定，利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，获得了较好的结果。它可用于分析、确定上述四种盐水溶液在太阳池内的浓度分布和变化，便于保持太阳池的稳定性。     

四种太阳池工质的浓度与折射率和温度的关系

选取可用作太阳池工质的ＮａＣｌ、ＣａＣｌ２、ＭｇＣｌ２和Ｎａ２ＣＯ３四种水溶液，对浓度Ｓ－折射率ｎ－温度Ｔ之间的关系进行测定，利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，获得了较好的结果。它可用于分析、确定上述四种盐水溶液在太阳池内的浓度分布和变化，便于保持太阳池的稳定性。     

盐梯度太阳池Kalina循环发电系统性能研究

Kalina循环发电系统是一种典型的低温热源发电系统,具有广阔的应用前景。盐梯度太阳池能够实现连续聚热和跨季节蓄热,可广泛应用于光热发电系统和光热供热系统。文章提出了一种以太阳池储热量为热源的盐梯度太阳池Kalina循环发电系统,并利用Aspen Hysys软件对该系统进行建模。而后根据模拟结果,研究了提热温度、运行压力和氨水浓度对该系统各项性能的影响。此外,还分析了典型工况下,该系统的热力性能。分析结果表明:随着提热温度逐渐升高,盐梯度太阳池Kalina循环发电系统的发电功率、热效率和效率均逐渐增加;随着运行压力逐渐升高,该系统的热效率和效率逐渐升高,并且存在最佳的运行压力1.75 MPa,使得该系统获得最大发电功率;随着氨水浓度逐渐增大,该系统的发电功率也会逐渐增大,但热效率和效率却逐渐降低;当氨水浓度为85%、运行压力为1.75 MPa、提热温度为90℃时,该系统的热效率和效率分别为7.93%,57.59%。     

Heterogeneous mixture distributions for modeling wind speed,application to the UAE

Heterogeneous mixture distributions (HTM) have not been employed for wind speed modeling of the Arabian Peninsula. In order to improve our understanding of wind energy potential in the Arabian Peninsula, HTM should be tested for the frequency analysis of wind speed. The aim of the current study is to assess the suitability of HTMs and identify the most appropriate probability distribution to model wind speed data in the UAE. Hourly mean wind speed data were used in the current study. Ten homogeneous and heterogeneous mixture distributions were used and constructed by mixing the four following probability distributions: Gamma, Weibull, Extreme value type-one, and Normal distributions. The Weibull and Kappa distributions were also employed as representatives of the conventional non-mixture distributions. Maximum Likelihood, Expectation Maximization algorithm, and Least Squares methods were employed to fit the mixture distributions. Results indicate that mixture distributions give the best fit to wind speed data for all stations. Wind speed data of five stations show strong mixture distributional characteristics. Applications of HTMs show a significant improvement in explaining the whole wind speed regime. The Weibull-Extreme value type-one mixture distribution is considered the most appropriate distribution for wind speed data in the UAE.     

WNS型燃油(气)锅炉炉内热流分布及温度分布的数值模拟

利用计算流体力学软件对WNS型卧式内燃燃油（气）锅炉内的流动，传热、传质进行了数值模拟，分别采用天然气和轻柴油为燃料，对炉膛内的热流分布，温度分布进行了比较分析，为WNS型锅炉的开发和设计提供了有效的研究手段。     

Maps of sky relative radiance and luminance distributions acquired with a monochromatic CCD camera

The purpose of this work is to characterize the sky relative radiance and luminance distributions from the analysis of sky images acquired using a monochromatic CCD wide angle lens camera. The proposed methodology is based on the reduction of the number of the gray levels from the original image, in order to sharpen the different regions of the sky hemisphere, resulting in low level gray scale maps. In these maps each gray level is related to an intensity level and each pixel is associated to a sky direction. An experimental system that is able to simultaneously supply images from the sky and solar irradiance data was developed using a commercial CCD camera. The sky relative radiance and luminance distributions for different sky conditions were also determined. The resultant maps agree with observations of the main characteristics of sky radiance and luminance distributions.     

基于火焰辐射图像的温度分布与浓度分布联合重建

讨论了基于火焰辐射图像的截面温度分布和碳粒浓度分布的重建测试方法。分析并建立了测试系统理模型和优化模型，设计了相应的求解算法，针对电站锅炉燃煤火焰进行了实际测试。计算结果与实际测试结果进行比较和分析，温度分布和浓度分布与模型重建结果比较接近，表明重建结果合理、可信。     

基于改进信息融合的配电变压器状态评估

为满足电力系统检修配电变压器的需要,提出了一种基于改进信息融合的配电变压器状态评估方法,以预防性试验和在线监测数据为基础,通过改进的层次分析法和模糊综合评估法获得评估指标的基本概率分布,利用修改后的证据源和修正后的合成规则对配电变压器状态进行评估。通过对某地区配电变压器实例分析,验证了该评估模型的有效性。该方法将预防性试验和在线监测数据相结合,有助于电力运营部门及时掌握分布广泛的配电变压器的运行状态,以便展开检修和维护。     

Performance analysis of HT-PEFC stacks

The performance analysis of a five-cell HT-PEFC stack is presented. The stack was operated either with pure hydrogen or synthetic reformate on the anode side and air on the cathode side. The overall electric performance and the heat management were analyzed. The local performance was assessed by current density and temperature distribution measurements. For this purpose, a tailor-made measuring board was integrated into the stack assembly. It is shown how the choice of fuel gas composition, reactant stoichiometry, flow direction and cooling affect the current density and temperature distribution.     

Study of species, temperature distributions and the solid oxide fuel cells performance in a 2-D model

A two-dimensional mathematical model for a planar SOFC (solid oxide fuel cell) is constructed. The distribution of the chemical species, the temperature and the performance (power) and the current density were calculated using a single-unit model with double channels of co-flow pattern. The finite volume method was employed for the calculation. The method was based on the fundamental conservation laws of continuity, momentum, energy and mass. The equations are implemented in FORTRAN language. The effects of several heat sources and flow rates on the calculated results were also investigated. The reference SOFC polarization curve has been calculated by imposing a uniform temperature of 800 K, a pressure equal to 1 atm; H₂ and O₂ molar fractions equal to 0.97 and 0.21 respectively. Results of temperature, chemical species distributions, performance and efficiency under several heat sources are shown and discussed. At a current density of about 23500 A/m², the power densities under all sources and chemical sources reached their maximums of 12965 W/m² and 16209 W/m² (i.e. 25% lower) respectively. However the temperature increment in the anode is analyzed toward all sources and chemical reaction. The temperature maximum values for each heat source type reached 1005.81 K and 984.69 K respectively.     

机组经济运行的负荷优化分配方法研究

并列运行的火电机组负荷优化分配是火电厂乃至电力系统优化运行的重要部分。在分析燃耗特性的基础上，建立了负荷优化分配的等微增率模型、线性规划模型和二次规划模型．并对某电力系统十台并列运行的单元机组进行求解计算，得到三种方法不同的负荷分配优化值和系统燃耗量。结果表明：二次规划分配方法节能效果最明显，线性规划分配方法的节能效果介于二次规划分配方法和等微增率分配方法之间。     

汽轮机转子钢晶间腐蚀沟槽宽度的统计特征研究

用化学腐蚀法对30Cr2MoV汽轮机转子钢进行晶间腐蚀测定,测出晶间腐蚀沟槽宽度。对沟槽宽度进行正态分布、对数正态分布、威布尔分布的统计拟和检验。统计检验方法采用柯尔莫哥洛夫一斯米尔诺夫（K—S）检验法检验。检验结果表明：晶间腐蚀沟槽宽度服从对数正态分布和威布尔分布。     

Effect of the compositional distribution on the photovoltaic power conversion of SiGe solar cells

Theoretical investigation on the photovoltaic power conversion of SiGe solar cells was carried out focusing on the impact of the compositional distribution. The absorption coefficient and the intrinsic carrier concentration were assumed to be macroscopically uniform parameters controlled by the compositional distribution. Under an assumption with finite minority carrier diffusion length, solar cell based on SiGe was revealed to have power conversion superior to that based on Si in a limited compositional window on the Si-rich side. In the window, the increase in the photocurrent density overcompensates the decrease in the voltage, and controls the overall conversion efficiency. The width of the window was greatly affected by the compositional distribution in SiGe. A comparison was made with experiments to support the existence of such a compositional window.