Generation Performance of Gas-Feed Direct Methanol Fuel Cell

Abstract

The modification effect of Nafion on the generation performance at different temperatures and methanol concentrations was investigated. The direct methanol fuel cell performances and electrochemical properties of the DMFC system using as-received Nafion117, a modified Nafion membrane, and using the Nafion117 MEA preparation by spray treatment on the surface of each catalyst layer for conductivity improvement. The open circuit voltage using the modified Nafion membrane was higher than that using Nafion117 at the cell temperature of 343–383 K and methanol concentration of 1.5–10 kmol/m³. The spray treatment of MEA was effective and improved the short circuit current up to 461 mA/cm² at a 5 kmol/m³ methanol concentration in comparison with no treatment of MEA because of the low interfacial resistance. The power density of 75 mW/cm² (no treatment Nafion117 MEA:40 mW/cm²) was obtained. The method of the spray treatment was found to be very effective for the DMFC system. The cell performance of Nafion117 MEA increased with the methanol concentration because of the reduction of the concentration overvoltage.     

膜的改性及其在环境领域应用研究进展

膜改性由于具有清洁、廉价、节能等特点,近年来得到快速发展,是解决膜污染的有效方法之一。本文综合介绍了膜的基体改性、表面改性这两种改性类型和目前常用的改性方法包括表面涂覆、表面活性剂改性、化学修饰改性、仿生改性等等,并简单介绍了膜改性在环境领域的应用,探讨了膜改性今后的发展。     

一体化-膜生物反应器物理清洗效果的研究

在一体式一膜生物反应器处理生活污水的基础上，考察了运行过程中膜污染情况。试验结果表明，膜外表面沉积污泥是造成膜污染的主要因素，在活性污泥混合液中搓洗膜丝，是一种方便而有效的清洗方式。间歇式运行方式的停抽期间最低剩余抽吸压力可用来表征运行过程中膜过滤性能的变化。     

燃料电池发展现状及在石油行业的应用可行性

一次能源利用效率低和分散能源回收难是石油天然气行业一直面临的技术难题。为提高一次能源利用和回收转换效率、解决能源与环境的矛盾,在石油行业内应用先进的节能环保新型技术——燃料电池技术是十分必要的。文章介绍了燃料电池的主要类型、特点及国内外应用现状,分析了其在石油行业的应用前景。     

改性PVDF中空纤维膜处理压裂返排液研究

针对中空纤维膜应用于水力压裂返排液处理时存在的膜污染严重、通量衰减快、影响处理效率等问题,研究了PVDF固含量、凝固浴温度等因素对PVDF膜性能的影响,通过非溶剂致相分离法制备了PVDF中空纤维膜,并采用表面接枝技术,对PVDF中空纤维膜进行了表面亲水化改性。压裂返排液吸附实验结果表明,表面接枝降低了PVDF的接触角,提高了膜的亲水性。与未接枝改性的PVDF膜相比,亲水改性后的PVDF膜表面吸附的压裂返排液更少。将亲水性中空纤维膜用于页岩气水力压裂返排液的过滤处理,应用结果表明其对压裂返排液中的总铁、SS、浊度、细菌去除率达到90%以上,长时间运行后的通量保持率高,有较好的抗膜污染性。     

植物油燃料研究概述

本文介绍了植物油作燃料的研究历史以及试验研究状况，表明植物油作为柴油的替代品是最易实现的方案。但植物油燃料还需进一步试验研究才能使其实用化，其技术储备具有深远的现实意义。本文还通过对燃料油植物栽培问题的探讨，认为“农林复合经营”是生产植物燃料油的重要途径。     

秸秆成型燃料与垃圾衍生燃料混合燃烧研究

生物质成型燃料和垃圾衍生燃料均是20世纪后期兴起的新型能源利用技术。低碳、环保的燃烧特性和可再生属性使其具有巨大的发展潜力,成为21世纪替代化石燃料潮流中的优先选择之一。文章对生物质秸秆成型燃料和垃圾衍生燃料RDF-5的燃烧效率进行了研究,由工业焚烧试验得到的燃烧技术指标对比和经济、社会效益分析,得出生物质秸秆成型燃料和垃圾衍生燃料混合燃烧的燃烧效率高于垃圾衍生燃料单独燃烧效率的结论。     

Treatment of Sulfate/Sulfide-Containing Wastewaters Using a Microbial Fuel Cell: Single and Two-Anode Systems

The microbial fuel cell (MFC) was employed to convert reductive potential in sulfate-laden wastewaters to electricity via reducing sulfate to sulfide by sulfate-reducing bacteria and then oxidizing sulfide to sulfur by exoelectrogens. The excess sulfide presented in the anodic solution inhibited the activities of functional strains in MFC. This study proposed the use of a two-anode system, with a sulfate-reducing bacteria anode and an exoelectrogen (C27) anode in the anodic cell, to efficiently convert reductive potential of sulfate into electricity. The microbial community of sulfate-reducing bacteria anode and the electrochemical characteristics of the studied MFCs were reported.     

水处理用活性炭改性研究

利用锆和氯化十六烷基三甲铵共同改性活性炭,制备一种新型去除污水中硝酸盐和磷酸盐的水处理吸附剂,并考察吸附剂加量、反应温度、pH值、共存阴离子等影响因素对吸附效果的影响。结果表明:锆-氯化十六烷基三甲铵改性活性炭(Zr-CTAC-AC)吸附剂适用于硝酸盐和磷酸盐浓度在100mg/L以下的污水,随着Zr-CTAC-AC加量的增加,硝酸盐、磷酸盐去除率逐渐增加,单位吸附量逐渐下降,Zr-CTAC-AC加量为8g/L时,硝酸盐去除率为79%,Zr-CTAC-AC加量为4.0g/L时,磷酸盐去除率可达91%,但应在较低的pH值范围内使用;反应温度对Zr-CTAC-AC的吸附效果影响不大;共存Cl-、HCO3^-和SO4^2-可使硝酸盐的吸附率降低,但对磷酸盐吸附率影响较小;1mol/L NaCl溶液可使吸附到Zr-CTAC-AC表面的硝酸盐90.9%左右被解吸出来,1mol/L NaOH溶液可使吸附到Zr-CTAC-AC表面的磷酸盐78.4%左右被解吸出来。Zr-CTAC-AC能够有效去除污水中硝酸盐和磷酸盐,制备方法简单,且可循环利用,处理成本低。     

Numerical Analysis of Heat Transfer and Gas Flow in PEM Fuel Cell Ducts by a Generalized Extended Darcy Model

Abstract

In this work, gas flow and heat transfer have been numerically investigated and analyzed for both cathode/anode ducts of proton exchange membrane (PEM) fuel cells. The simulation is conducted by solving a set of conservation equations for the whole domain consisting of a porous medium, solid structure, and flow duct. A generalized extended Darcy model is employed to investigate the flow inside the porous layer. This model accounts for the boundary-layer development, shear stress, and microscopic inertial force as well. Effects of inertial coefficient, together with permeability, effective thermal conductivity, and thickness of the porous layer on gas flow and heat transfer are investigated.     

基于消费者购车决策的购置税、燃油税节能减排效应分析

本文基于中国乘用车市场车型层面微观数据,采用前沿的需求模型估计方法,通过反事实分析,实证模拟了燃油税与购置税税率变动作用于消费者购车决策的价格收入效应与替代效应,进而从需求侧探究购置税与燃油税实现节能减排的微观经济学机制,兼论环境税对企业和社会总福利的影响。结论表明：燃油税具有显著的价格变动收入效应,即促使更多消费者放弃驾车出行模式,购置税具有显著的价格变动替代效应,即促使消费者选择购买小排量车型。在这样的机制下,组合税对需求的影响更多地取决于购置税,即购置税的价格替代效应超过燃油税的价格收入效应。这使得组合税在样本期并未实现总量上的节能减排,但税收组合政策使得中国乘用车市场车型平均油耗降低。从时间趋势来看,燃油税节能减排效应具有时间稳定性,购置税减排效果具有很大的波动性。从税制福利效应来看,组合税制的税收效应更多地向消费者市场转移。总的来看,燃油税与购置税的组合税政策并未实现“1+1＞ 2”的效应,未来减排工作的核心应在于通过调整和匹配税率,以实现组合税最优的政策效果。     

聚丙烯中空纤维膜生物反应器处理生活污水实验研究

在膜生物反应器中使用聚丙烯中空纤维膜材料的膜组件，可以解决以往其它材料寿命短、强度低、易污染等问题。利用这种膜生物反应器处理生活污水，其出水水质达到回用水标准，CODcr小于25mg／L；NH3-N小于5mg／L；浊度小于0．6NTU，可以回用于冲厕、绿化用水及河湖补充水。     

Thermal and Electrical Analysis in a Solid Oxide Fuel Cell Stack Using a Curved Profile for the Inlet Flow Rate Along the Stacking Direction

This study analyzes the cell temperature and current density fields of a solid oxide fuel cell stack, in which the inlet flow rate along the stacking direction of the fuel is either a curved profile derived through hydraulics or a progressively decreasing profile. The results show that the temperature field was neglibibly affected by the non-uniform inlet profile of the fuel, but the current density distribution was apparently affected. The difference in current density distribution between the curved profile and the progressively decreasing profile was small in the case of an solid oxide fuel cell (SOFC) with 10 stacks, but became larger in an SOFC with 20 stacks. In the 10-stack SOFC, the difference of current density between the uniform inlet flow and the curved inlet flow was less than 3%, whereas the deviation in the curved profile was less than 12%. However, in a 20-stack SOFC, the difference of current density was over 20%, whereas the deviation in the curved profile was more than 50%. Comparing the results between the curved and the progressively decreasing inlet profile indicates that the current density difference was over 20% in the 20-stack SOFC, but below 1% in the 10-stack SOFC. Therefore, a progressively decreasing inlet profile can replace a curved profile for analyzing an SOFC stack when the number of stacks is less than 10.     

各类固体表面处理及改性进展

表面改性,即对固体的表面进行处理,改变其表面性质,以达到我们需要的理想结果。研究表面性质的方法就是引入某种“探针”考察它与表面的相互作用,通过这种方法对改性前后的样品进行表征。现以催化剂载体表面、电极材料表面及塑料表面为例对表面改性的最新研究进展进行概述。     

中空纤维膜家用净水器工艺改良设计的探讨

针对家用净水器的市场情况,介绍了中空纤维膜超滤技术的工作原理和特点;提出用串联活性炭(或RO)过滤单元的组合模式可弥补该技术存在的不足;依据消费者对该类产品在净化功能等方面的需求,提出了改进建议。     

Decision Support for Road System Analysis and Modification on the Tahoe National Forest

The United States Forest Service is required to analyze road systems on each of the national forests for potential environmental impacts. We have developed a novel and inexpensive way to do this using the Ecosystem Management Decision Support program (EMDS). We used EMDS to integrate a user-developed fuzzy logic knowledge base with a grid-based geographic information system to evaluate the degree of truth for assertions about a roads environmental impact. Using spatial data for natural and human processes in the Tahoc National Forest (TNF, California, USA), we evaluated the assertion the road has a high potential for impacting the environment. We found a high level of agreement between the products of this evaluation and ground observations of a TNF transportation engineer, as well as occurrences of road failures. We used the modeled potential environmental impact to negatively weight roads for a least-cost path network analysis to 1573 points of interest in the forest. The network analysis showed that out of 8233 km of road analyzed in the forest, 3483 km (42%) must be kept in a modified road network to ensure access to these points. We found that the modified network had improved patch characteristics, such as significantly fewer cherry stem roads intruding into patches, an improved area-weighted mean shape index, and larger mean patch sizes, as compared to the original network. This analysis system could be used by any public agency to analyze infrastructure for environmental or other risk and included in other mandated analyses such as risks to watersheds.     

微滤膜技术及应用研究*

随着膜制造技术的发展,微滤膜在油田采出水处理中具有越来越大的优势。文章对微滤膜的特点和过滤分离原理进行了阐述,对比分析了有机高分子微滤膜、无机陶瓷微滤膜和复合微滤膜各自的优缺点、制备工艺以及在油田中的应用情况,针对微滤膜在采油污水处理中膜通量下降快,使用周期短等弱点提出了防止膜污染和膜清洗的措施,并对微滤膜的发展及今后在油田中的应用提出了建议和展望。     

百口泉地下水电导率与溶解性总固体相关性讨论

由于溶解性总固体的测定较为复杂,平行性、稳定性差,而电导率的测定简便、迅速,重现性、稳定性好,若二者相关关系显著,可通过测定电导率,按一定的比例推算水中溶解性总固体的量。通过对百口泉地下水的溶解性总固体与电导率的相关性的监测、分析,经统计检验,线性关系显著,其比值范围在065～076,均值为07,即百口泉地下水的电导率1μs/cm相当于070mg/L的溶解性总固体。     

油田采出水膜法处理技术应用研究进展

对采出水膜法处理技术中的微滤、超滤、纳滤、反渗透膜以及集成技术的应用进行研究,分析成本,总结各技术的特点。超滤、微滤主要处理的是水中的油类以及悬浮物和细菌,纳滤对二价离子的脱除率较高,反渗透技术可以有效降低采出水矿化度。在实际采出水处理中,可综合运用膜技术和生物法达到更好的处理效果。