Electric power generation from solar pond using combined thermosyphon and thermoelectric modules

Salinity-gradient solar ponds can collect and store solar heat at temperatures up to 80 °C. As a result, these water bodies act as a renewable source of low grade heat which can be utilized for heating and power generation applications. In this paper, design and test result of the combined system of thermosyphon and thermoelectric modules (TTMs) for the generation of electricity from low grade thermal sources like solar pond is discussed. In solar ponds, temperature difference in the range 40-60 °C is available between the lower convective zone (LCZ) and the upper convective zone (UCZ) which can be applied across the hot and cold surfaces of the thermoelectric modules to make it work as a power generator. The designed system utilizes gravity assisted thermosyphon to transfer heat from the hot bottom to the cold top of the solar pond. Thermoelectric cells (TECs) are attached to the top end of the thermosyphon which lies in the UCZ thereby maintaining differential temperature across them. A laboratory scale model based on the proposed combination of thermosyphon and thermoelectric cells was fabricated and tested under the temperature differences that exist in the solar ponds. Result outcomes from the TTM prototype have indicated significant prospects of such system for power generation from low grade heat sources particularly for remote area power supply. A potential advantage of such a system is its ability to continue to provide useful power output at night time or on cloudy days because of the thermal storage capability of the solar pond.     

Two-dimensional modeling of a salt-gradient solar pond with wall shading effect and thermo-physical properties dependent on temperature and concentration

In this paper,the behavior of a salt-gradient solar pond with the square cross-section has been studied experimentally and numerically.A small-scale solar pond were designed and built to provide quantitative data.A two-dimensional,transient heat and mass transfer model has been solved numerically by using finite-control-volume method.In this study,all the thermo-physical properties are variable as the function of temperature and salt concentration.Numerical results as obtained for the experimental pond have been satisfactorily compared and validated against measured data.Furthermore,the wall shading effect has been elaborated to improve the agreement between two sets of results.The temperature of the storage zone is predicted well by the model.It also can be observed that the initial concentration profile is preserved with time.The stability of the pond in time has been investigated in order to distinguish the critical zones.Finally,the application of an energy analysis gives an efficiency of about 12%for the pond.     

基于RS和GIS的南海区基塘用地时空变化分析

基塘地是珠三角地区特有的一种生态农业用地类型,在珠三角地区广泛分布,近20年来基塘地在数量和空间分布上发生了较大的变化。利用遥感(RS)和地理信息系统(GIS)技术能有效监测珠三角地区基塘地的变化。本文应用1990年、2000年、2008年3个时相的遥感数据,采用面向对象的方法,综合光谱、空间关系和形状等特征信息对研究区的基塘地进行提取,结果表明,1990-2000年研究区的基塘地面积呈增长趋势,2000-2008年该地区的基塘地面积锐减。对研究区的基塘地重心变化进行分析,结果表明,1990-2008年基塘地呈现向西北方向迁移的趋势。观测期内研究区增加的基塘地主要来源于耕地和林草地,而减少的基塘地主要转化为城镇建设用地、植被和耕地。本研究客观、准确地反演了研究区基塘用地的动态变化过程,并提出了基于可持续发展理论指导下的基塘地发展策略,对珠三角的基塘地综合开发管理和生态农业可持续发展具有一定的理论和现实意义。     

多级人工湿地-塘组合系统去除污染物研究

通过多级人工湿地-塘组合系统在不同的水力停留时间下处理污染水体,对各项出水污染物进行测试对比。结果表明:在初春低温条件下,COD,TN和NH₄⁺-N的去除率随着水力停留时间的增加显著提高,在保证处理效果的前提下,水力停留时间选择4 d较为合理。在水力停留时间为4 d时进行为期12个月的试验。试验结果表明:随着季节的变化,多级人工湿地-塘组合系统对模拟农村径流污水的净化效果保持在一个合理的波动范围内,在夏季时对污水中COD,TN以及NH₄⁺-N去除效果比在冬季时好。从试验去除污染物的效果可以看出,本系统可以在除污染物方面达到比较令人满意的效果,COD出水水质最好时为Ⅳ类水质,NH₄⁺-N出水水质最好时接近地表水Ⅳ类水质。     

生态塘深度处理石化废水尾水的效果及影响因素

采用由兼氧塘、好氧塘和水生植物塘串联而成的生态塘系统处理石化废水尾水,在中型试验装置上考察其处理效果及影响因素。结果表明: 经处理后,污水的COD降低率为25%～50%,系统出水的COD稳定在40～50 mg/L范围内,达到GB 18918-2002《城镇污水处理厂污染物排放标准》中的一级A标准中对COD的要求,但石油类物质浓度指标略微超标;温度是影响生态塘系统处理效果的主要因素,净水效果呈季节性变化,温度较高时处理效果较好,其对总氮（TN）去除的影响大于COD和总磷（TP）;光照对COD降低率、TP和TN去除率的影响较为相似,最高去除率均出现在16:00左右,夜间三者均出现一定程度的下降。     

尾矿库土石初期坝坡面沼泽化治理措施

对于初期坝为透水堆石坝、后期采用尾砂筑坝的上游式尾矿库,由于库水位高、干滩长度短、尾砂渗透性差、堆积坝坡陡、未设置排渗设施等原因,往往在后期尾矿堆积坝坡面出现沼泽化现象。目前对这种堆积坝坡面沼泽化的治理已积累了丰富的经验,而对于土石初期坝沼泽化现象,因出现较少,研究不多,治理措施也较少。通过对初期坝坡面沼泽化的原因分析和治理措施比选,将水平排渗管用于尾矿库土石初期坝坡面沼泽化治理中,根据浸润线观测及现场查看,经治理的土石初期坝浸润线埋深逐步降低、坡面沼泽化消除、坝体稳定性逐步提高,具有良好的治理效果。采用水平排渗管可消除土石初期坝沼泽化,施工中积累的经验可为类似工程治理提供借鉴。     

东山铁矿露天采场改建尾矿库边坡稳定性研究

以东山铁矿露天采场地质环境治理为背景,针对该采坑现状边坡及改造成尾矿库后终期边坡稳定性问题,通过矿山现状实测地形图及现场实地踏勘选取典型边坡剖面,利用Geo-studio软件中的SLOPE/W模块,对露天采场的边坡稳定性进行分析。通过数值模拟分析,得出所选典型剖面的边坡最危险滑裂面的位置以及在各种工况条件下的边坡安全系数,通过对比采用各种极限平衡分析方法所得的结果,东山露天采场边坡的最小安全系数为1.201,满足相关规范要求。研究结果表明：在拟定工况条件下采坑边坡大部分边坡剖面处于稳定状态,个别部位处于基本稳定状态,即总体安全稳定性有保障,但局部部位存在小规模崩塌、落石的可能性。总体而言,该露天采坑在改建成为尾矿库的过程中边坡安全性是有保障的。     

基于无线ZigBee的钨矿尾矿库安全监测系统

针对当前钨矿尾矿库安全监测系统存在安装和维护成本高、布线复杂、传输距离及能量受限等问题,设计了一种基于ZigBee无线传感器网络和LabVIEW的监测预警系统。选用片上芯片CC2530作为射频收发器,完成了太阳能供电的传感器节点的硬件和软件设计,实现对尾矿库监测数据的采集、传输和处理。上位机使用LabVIEW设计监测预警界面,实时显示监测参数并及时预警,利用VISA串口资源模块和SQL语言调用的Access数据库,实现监测数据的传输和存储。上位机数据处理模块通过LabVIEW的Matlab Script节点在后面板中编程调用Matlab软件并建立回归型支持向量机(SVR)模型进行测试。实验结果表明,系统能实时采集监测参数,SVR回归模型预测误差为0.3%左右,适合钨矿尾矿库的参数预测,对控制钨矿尾矿库风险,确保其安全意义重大。     

新立尾矿库综合治理措施及其实施效果

三山岛新立尾矿库由于特殊的近海地理位置,采取筑坝加高和植被护坡等措施对尾矿库进行综合治理,不仅增加了尾矿库的有效容积,还美化了周边环境,充分响应了国家“节能减排”的号召。