Thermo-economic investigation on the hydrogen production through the stored solar energy in a salinity gradient solar pond: A comparative study by employing APC and ORC with zeotropic mixture

In this paper, a salinity gradient solar pond (SGSP) is used to harness the solar energy for hydrogen production through two cycles. The first cycle includes an absorption power cycle (APC), a proton exchange membrane (PEM) electrolyzer, and a thermoelectric generator (TEG) unit; in the second one, an organic Rankine cycle (ORC) with the zeotropic mixture is used instead of APC. The cycles are analyzed through the thermoeconomic vantage point to discover the effect of key decision variables on the cycles’ performance. Finally, NSGA-II is used to optimize both cycles. The results indicate that employing ORC with zeotropic mixture leads to a better performance in comparison to utilizing APC. For the base mode, unit cost product (UCP), exergy, and energy efficiency when APC is employed are 59.9 $/GJ, 23.73%, and 3.84%, respectively. These amounts are 47.27 $/GJ, 29.48%, and 5.86% if ORC with the zeotropic mixture is utilized. The APC and ORC generators have the highest exergy destruction rate which is equal to 6.18 and 10.91 kW. In both cycles, the highest investment cost is related to the turbine and is 0.8275 $/h and 0.976 $/h for the first and second cycles, respectively. In the optimum state the energy efficiency, exergy efficiency, UCP, and H₂ production rate of the system enhances 42.44%, 27.54%,15.95%, and 38.24% when ORC with the zeotropic mixture is used. The maximum H₂ production is 0.47 kg/h, and is obtained when the mass fraction of R142b, LCZ temperature, pumps pressure ratio, generator bubble point temperature are 0.603, 364.35 K, 2.12, 337.67 K, respectively.     

高密度澄清池在邯钢第二污水处理厂的应用

高密度澄清池是一种新型高效的澄清池。介绍了高密度澄清池的工艺原理、运行条件和主要参数及在邯钢第二污水处理厂的应用情况。     

Big-Fish--Little-Pond effect on academic self-concept: A cross-cultural (26-country) test of the negative effects of academically selective schools.

Academically selective schools are intended to affect academic self-concept positively, but theoretical and empirical research demonstrates that the effects are negative. The big-fish--little-pond effect (BFLPE), an application of social comparison theory to educational settings, posits that a student will have a lower academic self-concept in an academically selective school than in a nonselective school. This study, the largest cross-cultural study of the BFLPE ever undertaken, tested theoretical predictions for nationally representative samples of approximately 4,000 15-year-olds from each of 26 countries (N=103,558) who completed the same self-concept instrument and achievement tests. Consistent with the BFLPE, the effects of school-average achievement were negative in all 26 countries (M beta=-.20, SD=.08), demonstrating the BFLPE's cross-cultural generalizability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Solar ponds in alkaline lake and oil well regions

Solar ponds are probably the simplest technology available for the useful conversion of solar energy. The basic technology is proven. Solar ponds have been shown to be technically feasible and economically viable for many applications, particularly for thermal use. The electrical conversion and use of solar energy via solar ponds is still questionable, in general, for economic viability. By putting the untapped sources together in the South Plains region, it looks promising economically both for thermal and electrical conversions and applications. There are a number of alkaline lake basins randomly scattered in the South Plains region of the U.S.A. In that area, there are thousands of crude oil producing wells that produce brine in abundance. The selection of suitable alkaline lake basins as a solar pond site and as depository sites of brine from oil wells and the using of this brine and salty water from alkaline lakes makes the solar pond economically viable for both thermal and electrical demands in the area.     

气浮池──稳定塘处理造纸废水

叙述了用气浮地→厌氧塘→兼性塘处理造纸废水的试验与设计。经运行后测定，出水达到了天津市水污染物排放标准的要求。气浮池采用３０％的回流比，提高了处理效率，每天可回收纸板原料８．４～１０．８ｔ。     

基于SPOT-5多光谱影像的矿区塌塘水体提取方法研究

针对基于遥感影像的水体提取方法存在水体提取不完整和误提的现象,提出了一种基于SPOT-5多光谱影像的矿区塌塘水体提取方法。在利用波段合成增加一个可用波段的基础上对已有的水体提取方法进行适当的改进,并基于决策树分类器和改进后的方法进行矿区水体的四级提取,保证了水体提取的完整性,同时减少了误提率;最后利用实测数据对水体提取的精度进行了评定。试验结果表明,基于决策树分类器的水体提取方法具有较高的精度,能满足矿区实际应用的需要。     

生态稳定塘系统在城市污水处理中的应用

介绍了生态稳定塘系统在德州市城市污水处理中的应用情况，对工程设计参数及其设计特色作了重点介绍，以资同行借鉴。     

尾矿库漫顶溃决动态演化及溃口展宽模型试验

为研究尾矿库漫顶溃决动态演化过程与溃口发展机理及规律,通过3组相似模型试验,对溃口展宽过程和演变机理进行了系统分析,提出了尾矿坝漫顶模式下溃口展宽速率的幂函数公式,并讨论了库水位上升阶段浸润线的变化过程及溃决阶段不同浸润线埋深条件下流速、流量、溃口宽度的变化过程。研究结果表明：尾矿坝的溃决过程可分为坝面漫流与冲沟形成、坝体崩塌与溃口快速扩张及稳定泄流3个阶段;浸润线埋深对流量、流速及溃口最终宽度有较大影响,排渗失效时峰值流量及溃口最终宽度接近正常排渗时的1.5倍,峰值流速可达1.2～1.3倍;降低浸润线高度可以延缓溃决泥石流到达下游的时间,紧急撤离时间也可延长3 min左右;提出的幂函数公式计算值与实测值吻合较好。     

江淮丘陵区塘坝灌溉能力估算及其演变特征

鉴于塘坝工程在江淮丘陵区蓄水灌溉中的重要作用,通过对塘坝工程与作物种植结构发展历程的综合分析,提出了基于水量供需平衡分析的塘坝灌区灌溉能力概念及其计算模型,定量评估了江淮丘陵区不同年代的塘坝灌溉能力,揭示了塘坝灌溉能力的动态演变特征。研究结果表明:江淮丘陵区全区塘坝灌溉能力在20世纪60年代达到峰值后,70～90年代呈显著下降趋势,至21世纪初有所回升。研究结果可为江淮丘陵区塘坝发展规划与灌溉制度的制定提供理论依据与技术支撑,具有重要实际指导意义。     

海水太阳池非稳态热质传递有限容积法模型

有限容积法与其他数值方法相比,是更具有实际物理意义的数值方法。本文采用有限容积数值计算方法,建立一维非稳态海水太阳池热质传递模型,动态描述太阳池蓄热和取热过程。通过数值求解已发表的工况,与其结果比较,验证了模型方法的正确性。本文还应用该模型,采用湛江地区2004年的大气环境温度和太阳辐射数据为计算条件,分析了海水太阳池在湛江地区应用时的热物性能。结果表明,海水太阳池有限容积法模型能准确描述太阳池的非稳态热质传递过程,太阳池池水温度随热负荷升高而降低,随非对流层厚度增加而升高,湛江地区气候适合应用太阳池技术。