Water removal characteristics of proton exchange membrane fuel cells using a dry gas purging method

Water removal from proton exchange membrane fuel cells (PEMFC) is of great importance to improve start-up ability and mitigate cell degradation when the fuel cell operates at subfreezing temperatures. In this study, we report water removal characteristics under various shut down conditions including a dry gas-purging step. In order to estimate the dehydration level of the electrolyte membrane, the high frequency resistance of the fuel cell stack was observed. Also, a novel method for measuring the amount of residual water in the fuel cell was developed to determine the amount of water removal. The method used the phase change of liquid water and was successfully applied to examine the water removal characteristics. Based on these works, the effects of several parameters such as purging time, flow rate of purging gas, operation current, and stack temperature on the amount of residual water were investigated.     

流变特性对稠油油藏产能的影响

由于稠油的流变特性不同于常规稀油，稠油油藏的产能分析也有别于常规稀油油藏。通过分析研究垂直井产能计算、稠油流变特性分析及启动压力梯度计算，建立了稠油油藏垂直井产能分析方法，指出了稠油油藏产能计算必须结合稠油流变特性和试井解释资料。并通过实例说明了该方法的应用。     

HWRR自动启动方式控制算法的设计

一、前言在HWRR上使用计算机,除了实现反应堆各参数的实时监测、在线计算与分析等功能外,还可以实现堆的自启动和功率的自动调节。启动时,反应堆在到达临界前,计算机可以按一定的程序控制各控制棒的起停顺序。当反应堆达到临界后;计算机将按一定的控制算法,自动地把堆功率升到预定值。如图1所示。由此可见,设计一种满意的启动方式是很重要的。     

催化裂化三机组启动方案及实施策略

主要阐述了永坪炼油厂800kt／a催化裂化装置主风机组(主机)启动程序和自动操作程序的实施策略，并根据用户电网特点探讨主电机直接启动和先烟机冲转再启动电机相并存启动方案的可能性，具体说明了在不同启动方案下投入自动操作程序的要点。     

市场条件下的机组启动费问题

机组在启动过程中需要耗费高额的启动费，这部分启动费是应由电网公司在制定日计划时予以考虑，还是应由发电公司在报价时自行考虑？针对这一问题，作者以对比机组启动费用与发电效益为出发点，提出了根据机组的启机效率，使用寿命以及国家现阶段的政策导向等多方面因素，由电力市场调度交易中心和发电公司以及市场监管部门兼顾各方利益，共同核定机组的含有技术和经济双重性的参数－“最小经济运行小时数”，并由发电公司依据机组自身特性和市场状况，自行处理启动费；而调度交易中心在制定竞价上网发电计划及结算时则不再单独考虑和支付机组启停费用的观点：文中同时还提出了分摊机组启动费的两种方法－平均分摊法和负荷比例分摊法，并对比了这两种分摊方法对双方经济性的影响。     

日产500吨脱墨浆生产线的设计

南纸股份有限公司日产500吨废纸脱墨浆生产线引进了Ahlstrom公司的碎浆系统和Andritz公司的脱墨系统，本文从设计角度叙述了其工艺过程、关键设备的特征及选型，对生产线的试车投产情况做了概要说明。     

兰州石化1.2 Mt/a柴油加氢装置开车及运行分析

介绍了中国石油兰州石化分公司1.2Mt/a柴油加氢装置,对其首次开车、运行和标定情况进行了总结,分析探讨了实际运行中存在的问题,并采取了相应的处理措施。结果表明:该柴油加氢工艺设计合理,能满足柴油的质量要求;在较缓和的反应条件下,DN-200催化剂脱硫率大于85%,含硫质量分数小于0.05%;标定时催化剂性能达到保证值要求,脱硫率97.1%,脱氮率大于66.7%。标定的综合能耗[m(标准油)/m(油品)]为10.73kg/t,低于设计值14.47kg/t。     

JY-2500型双色胶印机油墨辊电路防误启动设计

JY-2500型双色胶印机油墨辊的断料启动电路。在生产准备或维修中存在安全隐患。如何在不额外增添安全保护装置的前提下解决问题，本文给出分析与改进设计。     

A thyristor- and thermistor-based inrush current limiter for DC-link start-up

Large inrush currents can be harmful to equipment subjected to it and can also disturb other devices through voltage dips. Traditional ways of dealing with large inrush currents include the usage of parasitic elements in the supply, negative temperature coefficient (NTC) resistances and start-up relays. These solutions have several disadvantages among which are a non-negligible standby consumption, using a relay or a compromise between inrush current and load losses using an NTC. This paper proposes a solution which solves these disadvantages. The proposed circuit uses a semi-controlled bridge rectifier requiring a very low standby power consumption and is capable of withstanding grid interruptions. Moreover, it is designed to power on only when the load is not too heavy. This is accomplished by the use of positive temperature coefficient thermistors. The presented solution can be used for DC-link start-up circuits in applications with a power range from several watts up to a few kilowatts and it is particularly suitable for on-board battery chargers designed for electrical vehicles.     

低温高铁锰氨氮地下水两级生物净化工艺

针对"一级曝气+一级过滤"生物净化工艺处理低温(5~7.8℃)、高氨氮(ρ(NH_3-N)3.0 mg/L)、高铁锰(ρ(总Fe)12 mg/L,ρ(Fe~(2+))8.0 mg/L,ρ(Mn~(2+))3.0 mg/L)地下水出水锰和氨氮超标问题,开展两级曝气+两级过滤"净化工艺启动和铁锰氨氧化活性去除区位研究.两级生物净化工艺经133 d驯化培养启动成功,锰是影响启动周期长短的主要因素.启动成功后,氨氮去除负荷可达29.66 g/(m~2·h),锰去除负荷可达27.08 g/(m~2·h),产水量是单级净化工艺的2倍.铁锰氨氧化活性去除区位表明,铁在一级滤柱0~50 cm滤层内去除至痕量;55.23%的氨氮在一级滤柱中去除,主要集中在滤层0~135 cm段,44.10%的氨氮在二级滤柱中去除,主要集中在滤层0~50 cm段.锰和氨氮在氧化去除过程中存在显著分级,ρ(NH_3-N)2.25 mg/L时,会显著抑制锰氧化菌(MnOB)活性.锰在各级滤柱中的去除率和去除区位受进水氨氮质量浓度及滤速影响较大,滤柱启动成功后,仅有5.53%的锰在一级滤柱中去除,89.34%的锰在二级滤柱中去除.