这项工作得到了韩国国家研究基金会 (NRF) 资助的韩国政府 (MSIP: 科学、信息和通信技术和未来规划部) (No。NRF-2016M2B2A9911771)。

1. 实验程序 4 , 5 , 6 <ol> 准备步骤 <li> <ol> 检查实验设备。在测试矩阵的基础上, 仔细检查测试矩阵的测试条件, 如失水事故的大小, SBL 大小, 虹吸断路器的类型, 和存在的孔口, 在实验之前。此外, 测试, 以确认仪器和设备的组件工作正常, 没有数据噪音或故障. </li>
		<li> 使用安装在下部水箱中的回流泵将上部水箱装入水中. </li>
		<li> 卸下 SBL 内的剩余空气。使用真空泵和缓冲室去除 SBL 的残余空气. </li>
		<li> 检查上部水箱的初始水位。用附在油箱上的尺子. </li>
	</ol> </li> <li> 测试步骤 <ol> <li> 在管道系统的末尾打开阀门. </li>
		<li> 在控制室采用数据采集系统, 在虹吸破断现象期间, 检查测量数据, 如水位、流量、压力变化。如果没有流出的冷却剂, 第一个实验结束。最后, 用给定的测试条件记录所获得的实验结果. </li>
	</ol> </li> <li> 更改测试变量 (SBL 大小、失水事故大小、孔口存在和失水事故位置), 如下所示。
	<ol> <li> 将 SBL 的大小依次更改为2、2.5、3、4、5和 6; 给定的 SBL 在 图 2 中, 在位置2的法兰处连接到主管道. 
		注: 使用螺栓和螺母的法兰接头, 改变了实验变量, 如 SBL 尺寸、失水大小和孔板的存在。因此, 这些过程是手动进行的. </li>
		<li> 重复步骤 1.1.1 1.2.2 直到完成所有 SBL 大小的实验. </li>
		<li> 在位置为1的失水事故中, 将失水事故的大小依次更改为6、8、10、12、14和16英寸; 给定的减速器通过法兰接头连接到主管道上3位置 图 2 . </li>
		<li> 重复步骤 1.1.1-1.3.2 直到所有失水事故大小的实验完成. </li>
		<li> 安装通过上部水箱底部的法兰接头连接到主管道的孔板 (或卸下孔) 
		注: 前一步的实验是在孔口没有 (或存在) 的情况下进行的。因此, 应安装 (或删除) 的孔板下一次试验。
		<ol> <li> 要执行此工作, 请确保上部水箱中没有水. </li>
		</ol> </li> <li> 重复步骤 1.1.1-1.3.4。为了确认 SBL 和失水事故的影响, 在孔的存在 (或缺席), 重复上一步. </li>
		<li> 将失水事故更改为位置 2, 因为前一步的实验已经在失水事故位置1进行。更改下一次试验的失水位置. 
		注: 在实验装置中, 构造了两个失水位置。每个失水管道与一个隔离蝶阀连接到一个主管道系统。
		<ol> <li> 要更改失水事故的位置, 请关闭位于失水位置1处的隔离蝶阀, 然后在失水事故位置打开阀门 2. </li>
		</ol> </li> <li> 重复步骤 1.1.1-1.3.6. </li>
	</ol> </li> </ol> 2。运行模拟程序 <ol> <li> 单击程序图标以执行虹吸式断路器模拟程序. 
	注意: 该过程在 补充视频 1 中演示。如图所示, 模拟程序的初始屏幕由4按钮 (显示参数、运行、手动和退出) 组成。当用户单击 #39; 显示参数和 #39; 按钮时, 将打开一个新的命令窗口, 其中包含参数列表。用户可以修改和确认变量的数值。#39; 运行和 #39; 按钮通过将输入参数替换为包含的公式来执行计算。#39; 手动和 #39; 按钮用于通知使用和程序版本, 以及 #39; 退出和 #39; 按钮关闭程序。结果显示在和 #39; 显示结果和 #39; 窗口. </li>
	<li> 单击 #34; 显示参数和 #34; 按钮. </li>
	<li> 考虑到给定的模拟条件, 更改输入数据. </li>
	<li> 单击 #34; 运行和 #34; 按钮. </li>
	<li> 检查 #39 中的水位图形状; 显示结果和 #39; 窗口。程序按时间组织结果值, 并自动绘制图形。
	<ol> <li> 通过图形的形状, 直观地确认虹吸破碎的可能性; 如果水位或低于高度始终具有相同的值, 直到最终, 在给定的条件下, 虹吸断裂是可能的。请参见 图 3 . </li>
	</ol> </li> <li> 检查和 #39 中的其他输出; 显示结果和 #39; 窗口。请注意, 有八选项 (水位、低于高度、压力、流速、风速、two-phase 混合速度、数量和摩擦力) 来检查输出。使用复选框选择图形类型. 
	注意: 通过图可以看出每个值随时间变化的情况, 容易掌握虹吸式破碎现象. </li>
	<li> 根据时间单击和 #34 确定输出的特定值; 在特定时间和 #34 中计算; 按钮。输入所需的时间并根据设定的时间检查结果. </li>
	<li> 通过单击 #34 保存所有模拟结果数据; 保存数据和 #34; 按钮. 
	注意: 结果以文本文件的形式保存, 并将模拟条件保存在一起. </li>
</ol>

<ol>
	<li>McDonald, J., Marten, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> A Siphon Break as a Blocking Valve. , (1958).</li><li>. Siphon Breaker Design Requirements 12. Experimental and Analytical Study Available from: <a target="_blank" href="https://www.osti.gov/scitech/biblio/6623426">https://www.osti.gov/scitech/biblio/6623426</a> (1993)</li><li>Sakurai, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=JAERI-Research+99-016.">JAERI-Research 99-016.</a> Study for Improvements of Performance of the Test and Research Reactors. , (1999).</li><li>Kang, S. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Final Report of Experimental Studies on Siphon Breaker. , (2011).</li><li>Kang, S. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Experimental Study of Siphon breaker. , (2013).</li><li>Kang, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Siphon Breaker Design on Research Reactor with Real-Scale Experiment. , (2015).</li><li>Fossa, M., Guglielmini, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pressure+Drop+and+Void+Fraction+Profiles+during+Horizontal+Flow+through+Thin+and+Thick+Orifices.">Pressure Drop and Void Fraction Profiles during Horizontal Flow through Thin and Thick Orifices.</a> Exp. Thermal Fluid Sci. 26, 513-523 (2002).</li><li>Lee, K. Y., Kim, W. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+siphon+breaker+simulation+program+for+investing+loss+of+coolant+accident+of+a+research+reactor.">Development of siphon breaker simulation program for investing loss of coolant accident of a research reactor.</a> Ann. Nucl. Energy. 101, 49-57 (2017).</li><li>Lee, K. Y., Kim, W. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Theoretical+Study+on+Loss+of+Coolant+Accident+of+a+Research+Reactor.">Theoretical Study on Loss of Coolant Accident of a Research Reactor.</a> Nucl. Eng. Des. 309, 151-160 (2016).</li><li>Lee, K. Y., Seo, K. W., Chi, D. Y., Yoon, J. H., Kang, S. H., Kim, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+and+analytical+studies+on+the+siphon+breakers+in+research+reactor.">Experimental and analytical studies on the siphon breakers in research reactor.</a> European Research Reactor Conference. , 18-22 (2012).</li></ol>

作者没有什么可透露的。

虹吸断路器是一种被动操作的安全装置, 用于防止管道破裂事故发生时的冷却液损失。然而, 这是很难适用于当代研究反应堆, 因为没有实验的实际规模的研究反应堆。因此, 实际的实验是由 POSTECH 和 KAERI 进行的。试验的目的是确定虹吸破断在实际规模上是可行的, 并确定影响虹吸破碎的因素。实验结果表明, 失水的大小和 SBL 大小是影响低于的主要因素。
虹吸破碎的计算过于?...

使用板式燃料的反应堆的数量, 如约旦研究和训练反应堆 (JRTR) 和 KiJang 研究反应堆 (KJRR), 最近有所增加。为了方便地连接板式燃料 , 研究堆需要一个核心向动。由于研究反应堆需要主冷却系统的净正吸头, 一些冷却系统组件可能会安装在反应堆下面。然而, 如果管道破裂发生在反应堆下面的主冷却系统中, 虹吸效应会导致冷却剂的连续排水, 从而导致反应堆暴露在空气中。这意味着残余的热量不能被去除, 这可能导致严重的事故。因此, 在发生冷却剂事故时, 必须有防止发生严重事故的安全装置。虹吸式断路器是一种安全装置。它能有效地防止水的抽放, 利用空气的涌流。整个系统称为虹吸破碎系统。
对改进研究堆安全性进行了若干研究。麦当劳和貂1进行了一次实验, 以确认虹吸式破碎阀作为一个主动断路器的性能。尼尔和斯蒂芬斯2在小型管道中使用虹吸断路器作为被动操作装置进行了实验。樱井3提出了一个分析模型, 用于分析在完全分离的水下水流模型下的虹吸断裂。
虹吸破碎是非常复杂的, 因为有许多参数需要考虑。此外, 由于实际研究反应堆的实验尚未进行, 因此很难将以往的研究应用于当代的研究反应堆。因此, 以往的研究没有提出一个令人满意的理论模型的虹吸断裂。为此, 进行了实际实验, 建立了理论模型。
为探讨虹吸式断路器对研究堆的影响, 由浦科技大学 (POSTECH) 和韩国原子能研究所 (KAERI)4,5 进行了实际规模验证实验. ,6。图 1是虹吸断路器试验的实际设备。图 2显示了设施的示意图, 其中包括设施标记。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/55972/55972fig1.jpg"> 
图1。虹吸式破碎示范试验装置.主要管道尺寸为 16, 并安装一个亚克力窗口进行观察。该孔是一种用来描述压降的装置。因此, 在上部水箱的底部有一个孔组件。<a href="//ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55972/55972fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/55972/55972fig2.jpg"> 
图2。实验装置的原理图.给出了测量点的位置。这些数字表明这些有关地点;点0表示虹吸断路器的入口, 点1表示水位, 点2表示虹吸断路器和主管道的连接部分, 点3表示失水位置。<a href="//ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55972/55972fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
虹吸断路器试验装置由上罐、下罐、管路系统和回流泵组成。上部坦克的容量是 57.6 m3。底部区域和深度分别为 14.4 m2 (4 m x 3.6 m) 和 4 m。较低的油箱和失水事故的位置位于8.3 米以下的上部坦克。下槽容量为 70 m3。在实验中, 较低的水箱被用来储存水。下油箱与回流泵相连。下部水箱中的水被泵入上层水箱。管道系统的主要管道尺寸为16。虹吸断路器 (SBL) 的末端位于11.6 米高的低管断裂点之上。此外, 在管道上安装了亚克力窗口以进行可视化, 如图 1所示。
安装了几个设备来测量物理信号。使用了两个绝对压力传感器 (APTs) 和三差压传感器 (DPTs)。为了测量水质量流量, 采用了超声波流量计。数据采集系统被用来获取所有的测量数据在250毫秒的时间间隔。除了测量设备外, 还安装了摄像头进行观察, 并在上部水箱的内壁上附一把尺子, 以检查水位。
试验中考虑了各种失水事故和虹吸断路器 (SB) 的尺寸、虹吸开关类型 (线/孔) 以及反应器燃料和管路破裂点的存在。为了验证失水和 SBL 大小的影响, 采用了不同大小的失水和 SBL。失水事故的大小从6到 16, SBL 的大小从2到6不等。在实验中, 采用了虹吸式断路器的线型和孔型, 但本研究的以下内容只考虑了 JRTR 和 KJRR 中使用的 SBL 型。作为实验结果的一个例子,图 3是一个包含压力和水流速率数据的图。实验于2013年10月4日进行, 实验数据样本为 LN23 (线型 SB, 无孔, 12 失水, 2.5 SBL)。
通过实验数据, 建立了能预测虹吸破断现象的理论模型。理论模型以伯努利方程开始。从伯努利方程得到流体的流速, 通过将流体的流速乘以管道面积, 可以得到容积流速。此外, 还可以利用容积流速来获得水位。理论模型的基本概念如下。然而, 由于虹吸破碎现象是一个 two-phase 的流动, 有额外的点需要考虑。为了考虑 two-phase 流分析模型, 进行了精度验证试验。由于奇泽姆模型比均质模型更精确, 因此采用奇泽姆模型对该现象进行分析。根据奇泽姆模型, two-phase 乘数公式表示为公式 17。在这个等式, ф代表 two-phase 乘数, ρ代表密度, 并且 X 代表质量。
<img alt="Equation 1" src="/files/ftp_upload/55972/55972eq1.jpg">(1)
p 类 = "jove_content" > 在奇泽姆模型中, 包含了随质量流变化的系数 B。最后, 推导了奇泽姆系数 B 与反应器设计条件之间的相关公式, 是理论模型的一个重要观点。换言之, 实验的另一个目的是获取数据, 以确定设计条件与奇泽姆系数 B 之间的关系。从试验结果出发, 建立了设计条件与奇泽姆系数 B 之间的相关公式。由此建立的理论模型可以较好地预测虹吸断裂现象。
此外, 还开发了一个具有图形用户界面 (GUI) 的仿真程序。通过在图 3中绝对压力数据的转换, 可以将此现象划分为三阶段: 冷却剂的损耗 (单相流动)、虹吸断裂 (两相流) 和稳态。因此, 该算法的主要计算过程包括一个与实际现象的三阶段相对应的三步过程。包括计算过程中, 描述模拟过程的整个算法如图 48所示。
使用该软件 (请参见补充视频 1) 开始模拟, 用户输入与设计条件相对应的输入法参数, 输入参数存储为固定值。如果用户在输入参数后进行模拟, 程序将执行第一步计算。第一步是单相计算, 即在管道破裂后, 由于虹吸效应造成的冷却剂损失的计算。这些变量由理论模型 (如伯努利方程、质量流保存、等) 自动计算, 并从用户输入的参数中进行计算。计算结果按用户指定的时间单位依次存储在计算机存储器中。
如果水位下降低于位置 0, 这意味着单相流动的结束, 因为空气开始冲进 SBL 在这一刻。因此, 单相流动的第一步, 直到水位达到0位。当水位处于0位时, 这意味着低于高度为零。低于高度是 SBL 的入口与虹吸断裂后上部水箱水位的高度差。换言之, 低于高度表明在虹吸破断过程中水位下降的幅度。因此, 低于高度是一个重要的参数, 因为它将允许直接确定的数量的冷却剂损失。因此, 该程序根据低于高度确定第一步计算的结束。
如果低于高度大于零, 程序执行第二步计算, 可以模拟 two-phase 流。由于虹吸破碎阶段存在水和气流, 因此必须考虑两种流体的物理性质。因此, 在这个计算步骤中考虑了 two-phase 乘数、质量和空隙率的值。特别地, 用空分式值作为第二步计算的结束判据。空隙率可表示为空气流量与空气和水流之和的比值。第二步演算继续, 直到空隙分数 (α) 价值是0.9。当α超过 0.9, 第三步演算收益描述稳定状态。从理论上讲, 虹吸断裂的结束判据是α = 1, 因为此时管道中只有空气存在。然而, 在这个程序中, 虹吸断裂的最终标准是α = 0.9, 以避免在计算过程中出现任何错误。因此, 部分损失的结果是不可避免的, 但这个错误可以忽略不计。
稳定状态计算在用户设置的时间内进行。由于没有进一步的变化, 稳态的特点是计算结果值总是恒定的。如果虹吸断裂是成功的, 最后水平的水在上部坦克将保持在一个特定的值, 而不是零。然而, 如果虹吸断裂没有成功地执行, 冷却剂将几乎丢失, 并且水的最后水平接近零价值。因此, 如果水位值等于零, 则表明给定的设计条件不足以完成虹吸破断。
计算后, 用户可以通过各种方式确认结果。结果表明, 虹吸破碎、虹吸破碎、奇异性等情况。该仿真程序能够对这一现象进行真实的预测和分析, 并有助于虹吸式断路器系统的设计。本文介绍了实验方案、实验结果和仿真程序的应用。

<table><tbody><tr><td>Absolute pressure transducer</td><td>Sensor Technics</td><td>CTE9000</td><td>0.05% full-scale error</td></tr><tr><td>Differential pressure transducer</td><td>Setra</td><td>C230</td><td>0.25% full-scale error</td></tr><tr><td>Ultrasonic flow meter</td><td>Tokyo Keiki</td><td>UFP-20</td><td>Resolution 0.01m^3/h</td></tr><tr><td>Visual Studio 2012</td><td>Microsoft</td><td>Windows 8</td><td>Microsoft Foundation Class</td></tr><tr><td>E.R.W. steel pipe</td><td>Hyundai Hysco</td><td>KS D 3507(SPP)</td><td>400A(out dia.) x 7.9mm(thickness)</td></tr></tbody></table>

study of siphon breaker experiment and simulation for a research reactor

在研究堆的设计条件下, 管道破裂引起的虹吸现象会导致水的持续向外流动。为了防止这种外流, 需要一个控制装置。虹吸式断路器是一种安全装置, 可以有效地控制冷却水的损失。
为了分析虹吸破碎的特点, 进行了实际的实验研究。从实验结果中发现, 影响虹吸破碎现象的设计因素有多种。因此, 在各种设计条件下, 有必要建立一个能够预测和分析虹吸断裂现象的理论模型。利用实验数据, 可以建立一个准确预测虹吸破断现象的进展和结果的理论模型。建立的理论模型以流体力学为基础, 采用奇泽姆模型对 two-phase 流进行分析。从伯努利方程出发, 可以求得或计算 two-phase 流的速度、数量、低于高度、水位、压力、摩擦系数和相关因素。此外, 为了利用本研究所建立的模型, 研制了虹吸式断路器分析与设计方案。仿真程序在理论模型的基础上运行, 并以图的形式返回结果。用户可以通过检查图形的形状来确认虹吸断裂的可能性。此外, 整个仿真结果的保存是可行的, 可以作为分析实际虹吸破碎系统的一种资源。
最后, 使用本研究开发的程序, 用户可以确定虹吸式破碎机的状态, 设计虹吸式破碎机系统。

虹吸破碎的全过程由三阶段组成。第一阶段是由于虹吸效应而流出的冷却剂。第二阶段是通过 SBL 来启动空气流入的过程, 以阻止冷却剂的流失, 称为虹吸破碎。在图 3中, 虹吸断裂现象可以看作是绝对压力的急剧增加。在绝对压力急剧增加后, 由于水位下降而逐渐减少。在虹吸结束时, 由于一些残余水回流到上部水箱, 绝对压力再次增加。如果虹吸破碎...

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Study of Siphon Breaker Experiment and Simulation for a Research Reactor

对虹吸破断现象进行了实验研究, 并提出了理论模型。建立了基于理论模型的仿真程序, 并与实验结果进行了比较。仿真结果与实验结果吻合较好。

研究堆虹吸断路器试验与仿真研究

Under the design conditions of a research reactor, the siphon phenomenon induced by pipe rupture can cause continuous outward flow of water. To prevent ...

study-siphon-breaker-experiment-simulation-for-research

Research

JoVE Journal

Engineering

8.7K 次观看.  Handong Global University. 对虹吸破断现象进行了实验研究, 并提出了理论模型。建立了基于理论模型的仿真程序, 并与实验结果进行了比较。仿真结果与实验结果吻合较好。

视频: Study of Siphon Breaker Experiment and Simulation for a Research Reactor

Activating Molecules, Ions, and Solid Particles with Acoustic Cavitation

The chemical and physical effects of ultrasound arise not from a direct interaction of molecules with sound waves, but rather from the acoustic cavitation: the nucleation, growth, and implosive collapse of microbubbles in liquids submitted to power ultrasound. The violent implosion of bubbles leads to the formation of chemically reactive species and to the emission of light, named sonoluminescence. In this manuscript, we describe the techniques allowing study of extreme intrabubble conditions and chemical reactivity of acoustic cavitation in solutions. The analysis of sonoluminescence spectra of water sparged with noble gases provides evidence for nonequilibrium plasma formation. The photons and the "hot" particles generated by cavitation bubbles enable to excite the non-volatile species in solutions increasing their chemical reactivity. For example the mechanism of ultrabright sonoluminescence of uranyl ions in acidic solutions varies with uranium concentration: sonophotoluminescence dominates in diluted solutions, and collisional excitation contributes at higher uranium concentration. Secondary sonochemical products may arise from chemically active species that are formed inside the bubble, but then diffuse into the liquid phase and react with solution precursors to form a variety of products. For instance, the sonochemical reduction of Pt(IV) in pure water provides an innovative synthetic route for monodispersed nanoparticles of metallic platinum without any templates or capping agents. Many studies reveal the advantages of ultrasound to activate the divided solids. In general, the mechanical effects of ultrasound strongly contribute in heterogeneous systems in addition to chemical effects. In particular, the sonolysis of PuO2 powder in pure water yields stable colloids of plutonium due to both effects.

Acoustic cavitation in liquids submitted to power ultrasound creates transient extreme conditions inside the collapsing bubbles, which are the origin of unusual chemical reactivity and light emission, known as sonoluminescence. In the presence of noble gases, nonequilibrium plasma is formed. The "hot" particles and the photons generated by collapsing bubbles are able to excite species in solution.

活化分子，离子和固体颗粒与声空化

The chemical and physical effects of ultrasound arise not from a direct interaction of molecules with sound waves, but rather from the acoustic ...

科研

化学

Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor

The importance of microbial sulfate reduction relies on the various applications that it offers in environmental biotechnology. Engineered sulfate reduction is used in industrial wastewater treatment to remove large concentrations of sulfate along with the chemical oxygen demand (COD) and heavy metals. The most common approach to the process is with anaerobic bioreactors in which sulfidogenic sludge is obtained through adaptation of predominantly methanogenic granular sludge to sulfidogenesis. This process may take a long time and does not always eliminate the competition for substrate due to the presence of methanogens in the sludge. In this work, we propose a novel approach to obtain sulfidogenic sludge in which hydrothermal vents sediments are the original source of microorganisms. The microbial community developed in the presence of sulfate and volatile fatty acids is wide enough to sustain sulfate reduction over a long period of time without exhibiting inhibition due to sulfide. 
This protocol describes the procedure to generate the sludge from the sediments in an upflow anaerobic sludge blanket (UASB) type of reactor. Furthermore, the protocol presents the procedure to demonstrate the capability of the sludge to remove by reductive dechlorination a model of a highly toxic organic pollutant such as trichloroethylene (TCE). The protocol is divided in three stages: (1) the formation of the sludge and the determination of its sulfate reducing activity in the UASB, (2) the experiment to remove the TCE by the sludge, and (3) the identification of microorganisms in the sludge after the TCE reduction. Although in this case the sediments were taken from a site located in Mexico, the generation of a sulfidogenic sludge by using this procedure may work if a different source of sediments is taken since marine sediments are a natural pool of microorganisms that may be enriched in sulfate reducing bacteria.

Microbial sulfate reduction is a process of great importance in environmental biotechnology. The success of the sulfidogenic reactors depends among other factors on the microbial composition of the sludge. Here, we present a protocol to develop sulfidogenic sludge from hydrothermal vents sediments in a UASB reactor for reductive dechlorination purposes.

Sulfidogenic污泥海洋沉积物和三氯乙烯减少在上流式厌氧污泥床反应器开发

The importance of microbial sulfate reduction relies on the various applications that it offers in environmental biotechnology. Engineered sulfate ...

环境科学

Chemical Gardens as Flow-through Reactors Simulating Natural Hydrothermal Systems

Here we report experimental simulations of hydrothermal chimney growth using injection chemical garden methods. The versatility of this type of experiment allows for testing of various proposed ocean / hydrothermal fluid chemistries that could have driven reactions toward the origin of life in environments on the early Earth, early Mars, or even other worlds such as the icy moons of the outer planets. We show experiments that include growth of chemical garden structures under anoxic conditions simulating the early Earth, inclusion of trace components of phosphates / organics in the injection solution to incorporate them into the structure, a switch of the injection solution to introduce a secondary precipitating anion, and the measurement of membrane potentials generated by chemical gardens. Using this method, self-assembling chemical garden structures were formed that mimic the natural chimneys precipitated at submarine hydrothermal springs, and these precipitates can be used successfully as flow-through reactors by feeding through multiple successive &#8220;hydrothermal&#8221; injections.

We describe chemical garden formation via injection experiments that allow for laboratory simulations of natural chemical garden systems that form at submarine hydrothermal vents.

化工园为直通式反应器模拟自然热液系统

Here we report experimental simulations of hydrothermal chimney growth using injection chemical garden methods. The versatility of this type of experiment ...

Laser-heating and Radiance Spectrometry for the Study of Nuclear Materials in Conditions Simulating a Nuclear Power Plant Accident

Major and severe accidents have occurred three times in nuclear power plants (NPPs), at Three Mile Island (USA, 1979), Chernobyl (former USSR, 1986) and Fukushima (Japan, 2011). Research on the causes, dynamics, and consequences of these mishaps has been performed in a few laboratories worldwide in the last three decades. Common goals of such research activities are: the prevention of these kinds of accidents, both in existing and potential new nuclear power plants; the minimization of their eventual consequences; and ultimately, a full understanding of the real risks connected with NPPs. At the European Commission Joint Research Centre&#39;s Institute for Transuranium Elements, a laser-heating and fast radiance spectro-pyrometry facility is used for the laboratory simulation, on a small scale, of NPP core meltdown, the most common type of severe accident (SA) that can occur in a nuclear reactor as a consequence of a failure of the cooling system. This simulation tool permits fast and effective high-temperature measurements on real nuclear materials, such as plutonium and minor actinide-containing fission fuel samples. In this respect, and in its capability to produce large amount of data concerning materials under extreme conditions, the current experimental approach is certainly unique. For current and future concepts of NPP, example results are presented on the melting behavior of some different types of nuclear fuels: uranium-plutonium oxides, carbides, and nitrides. Results on the high-temperature interaction of oxide fuels with containment materials are also briefly shown.

We present experiments in which real nuclear fuel, cladding, and containment materials are laser heated to temperatures beyond 3,000 K while their behavior is studied by radiance spectroscopy and thermal analysis. These experiments simulate, on a laboratory scale, the formation of a lava-phase following a nuclear reactor core meltdown.

核材料在核电厂事故模拟条件下的激光加热和辐射光谱研究

Major and severe accidents have occurred three times in nuclear power plants (NPPs), at Three Mile Island (USA, 1979), Chernobyl (former USSR, 1986) and ...

In Situ Visualization of the Phase Behavior of Oil Samples Under Refinery Process Conditions

To help address production issues in refineries caused by the fouling of process units and lines, we have developed a setup as well as a method to visualize the behavior of petroleum samples under process conditions. The experimental setup relies on a custom-built micro-reactor fitted with a sapphire window at the bottom, which is placed over the objective of an inverted microscope equipped with a cross-polarizer module. Using reflection microscopy enables the visualization of opaque samples, such as petroleum vacuum residues, or asphaltenes. The combination of the sapphire window from the micro-reactor with the cross-polarizer module of the microscope on the light path allows high-contrast imaging of isotropic and anisotropic media. While observations are carried out, the micro-reactor can be heated to the temperature range of cracking reactions (up to 450 &#176;C), can be subjected to H2 pressure relevant to hydroconversion reactions (up to 16 MPa), and can stir the sample by magnetic coupling. 
Observations are typically carried out by taking snapshots of the sample under cross-polarized light at regular time intervals. Image analyses may not only provide information on the temperature, pressure, and reactive conditions yielding phase separation, but may also give an estimate of the evolution of the chemical (absorption/reflection spectra) and physical (refractive index) properties of the sample before the onset of phase separation.

In Situ Visualization of the Phase Behavior of Oil Samples Under Refinery Process Conditions

This article describes a setup and method for the in situ visualization of oil samples under a variety of temperature and pressure conditions that aim to emulate refining and upgrading processes. It is primarily used for studying isotropic and anisotropic media involved in the fouling behavior of petroleum feeds.

在油样品的相行为在炼油工艺条件的原位可视化

To help address production issues in refineries caused by the fouling of process units and lines, we have developed a setup as well as a method to ...

工程学

Optimization, Test and Diagnostics of Miniaturized Hall Thrusters

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without attendance and adjustment. Thermochemical thrusters which utilize thermodynamic properties of gases as a means of acceleration have physical limitations on their exhaust gas velocity, resulting in low efficiency. Moreover, these engines demonstrate extremely low efficiency at small thrusts and may be unsuitable for continuously operating systems which provide real-time adaptive control of the spacecraft orientation, velocity and position. In contrast, electric propulsion systems which use electromagnetic fields to accelerate ionized gases (i.e., plasmas) do not have any physical limitation in terms of exhaust velocity, allowing virtually any mass efficiency and specific impulse. Low-thrust Hall thrusters have a lifetime of several thousand hours. Their discharge voltage ranges between 100 and 300 V, operating at a nominal power of &lt;1 kW. They vary from 20 to 100 mm in size. Large Hall thrusters can provide fractions of millinewton of thrust. Over the past few decades, there has been an increasing interest in small mass, low power, and high efficiency propulsion systems to drive satellites of 50-200 kg. In this work, we will demonstrate how to build, test, and optimize a small (30 mm) Hall thruster capable of propelling a small satellite weighing about 50 kg. We will show the thruster operating in a large space environment simulator, and describe how thrust is measured and electric parameters, including plasma characteristics, are collected and processed to assess key thruster parameters. We will also demonstrate how the thruster is optimized to make it one of the most efficient small thrusters ever built. We will also address challenges and opportunities presented by new thruster materials.

Here, we present a protocol to test and optimize space propulsion systems based on miniaturized Hall-type thrusters.

小型化霍尔推进器的优化、测试和诊断

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without ...

Interactive and Visualized Online Experimentation System for Engineering Education and Research

Experimentation is crucial in engineering education. This work explores visualized experiments in online laboratories for teaching and learning and also research. Interactive and visualizing features, including theory-guided algorithm implementation, web-based algorithm design, customizable monitoring interface, and three-dimensional (3-D) virtual test rigs are discussed. To illustrate the features and functionalities of the proposed laboratories, three examples, including the first-order system exploration using a circuit-based system with electrical elements, web-based control algorithm design for virtual and remote experimentation, are provided. Using user-designed control algorithms, not only can simulations be conducted, but real-time experiments can also be conducted once the designed control algorithms have been compiled into executable control algorithms. The proposed online laboratory also provides a customizable monitoring interface, with which users can customize their user interface using provided widgets such as the textbox, chart, 3-D, and camera widget. Teachers can use the system for online demonstration in the classroom, students for after-class experimentation, and researchers to verify control strategies.

This work describes an online experimentation system that provides visualized experiments, including the visualization of theories, concepts, and formulas, visualizing the experimental process with three-dimensional (3-D) virtual test rigs, and visualizing the control and monitoring system using widgets such as charts and cameras.

工程教育研究互动可视化在线实验系统

Experimentation is crucial in engineering education. This work explores visualized experiments in online laboratories for teaching and learning and also ...

A Modeling and Simulation Method for Preliminary Design of an Electro-Variable Displacement Pump

Electro-hydrostatic actuators (EHAs) have been considerably researched in academia, and their applications in various industrial fields are expanding. The variable-speed EHA has now taken priority over the variable-displacement EHA, but its driving motor and associated electronics encounter issues when applied in high-power applications: low-dynamics, high thermal dissipation, high price, etc. Therefore, a variable-displacement EHA equipped with an electro-variable displacement pump (EVDP) has been considered. The EVDP itself is a mechatronic system that integrates a piston pump, a ball screw, a gearbox, and a permanent magnet synchronous motor (PMSM). Consequently, the EVDP needs to be investigated to ensure its system-level performance when applied in an EHA. In addition to the previous research on the technical parameters of the EVDP, a dedicated design method is necessary for further reducing the cost of using the EVDP and exploring its performance potential. Here, a simulation based EVDP preliminary design method is selected for designing a 37 kW EVDP. Firstly, a previously proposed multidisciplinary model of the EVDP is extended by improving the parameter generation, including the EVDP life, reliability, control models, etc. Secondly, the proposed model is partially verified using a downsized prototype. Thirdly, the EVDP is simulated at a system level, supported by the proposed model. The EVDP performance is evaluated according to the specified design requirements. The temperature, bandwidth and accuracy, reliability and lifetime, etc., are all predicted for the EVDP. The simulation results demonstrate the EVDP's applicability in variable-displacement EHA. The proposed modeling and simulation method can be used to evaluate diverse EVDP performance and respond to general design requirements. The method can also support the resolution of the preliminary design challenges in terms of limited information and robustness. Therefore, the proposed method is appropriate for the realization of the simulation-based EVDP preliminary design method.

A simulation model specifically supporting the preliminary design of an electro-variable displacement pump (EVDP) is developed and partially verified by experiments. The control performance, life, reliability, etc., can all be evaluated using the proposed model, which covers the main performance requirements under the EVDP preliminary design task.

一种电动变量泵初步设计的建模与仿真方法

Electro-hydrostatic actuators (EHAs) have been considerably researched in academia, and their applications in various industrial fields are expanding. The ...

Experimental Multiscale Methodology for Predicting Material Fouling Resistance

The buildup of fouling deposits in energy systems degrades their ability to transfer heat, reducing efficiency and causing operational issues such as localized corrosion. Each application presents its own challenges. In nuclear power generation, the buildup of CRUD (Chalk River Unidentified Deposits) induces unique, negative effects ranging from reduced heat transfer, to axial power shifting, to CRUD-induced localized corrosion (CILC), the last of which can cause sudden fuel failure. Knowledge of why CRUD forms and how to prevent its adhesion to nuclear fuel rods represents a major step towards eliminating it. This paper demonstrates a methodology to ascertain which materials may resist CRUD adhesion, thereby preventing its initiation and growth. It presents experiments targeted at multiple length scales: pool boiling (macroscale), which simulates CRUD initiation processes in a nuclear reactor, and atomic force microscope (AFM) force spectroscopy (microscale), which yields quantitative measurements of the adhesion between CRUD constituents and candidate CRUD-resistant materials. Early data from both sets of experiments show some correlation, suggesting that AFM force spectroscopy (AFM-FS) may be used to pre-screen materials for fouling resistance. So far, it appears that CRUD constituents adhere well to oxides, while carbides show both greatly reduced adhesion and no adherent CRUD in pool boiling experiments. The relationship between the AFM-FS measurements and the growth of CRUD in the pool boiling experiments may provide insight into the possible factors affecting fouling in nuclear reactors, eventually leading to its elimination.

Fouling, or corrosion product deposition, plagues numerous fields of energy production. At its core is adhesion between dissimilar materials. Understanding and controlling adhesion could reduce or eliminate fouling. This paper demonstrates pool boiling experiments (macroscale) and atomic force microscope force-spectroscopy measurements (microscale), which when in agreement, indicate fouling-resistance.

The buildup of fouling deposits in energy systems degrades their ability to transfer heat, reducing efficiency and causing operational issues such as ...

生物学

Single and Two-phase Flow in a Packed Bed Reactor

Source: <a href="https://www-jove-com.remotexs.ntu.edu.sg/author/Kerry+M._Dooley">Kerry M. Dooley</a> and Michael G. Benton, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA
The goal of this experiment is to determine the magnitude of maldistribution in typical packed bed reactors in both single phase and two-phase (gas-liquid) flow and evaluate the effects of this maldistribution on pressure drop. The concepts of residence time distribution and dispersion are introduced through the use of tracers, and these concepts are related to physical maldistribution.
Channeling in a single-phase flow can occur along walls or by preferential flow through a larger portion of the bed cross-section. Channeling in two-phase flow can result from even more complex causes, and simple two-phase flow theories seldom predict pressure drops in packed beds. A design goal is always to minimize the extent of channeling by finding the optimal bed and particle diameters for the design flow rates and by packing a bed in a way to minimize settling. It is always important to quantify how much maldistribution might occur and to over-design the unit to account for its occurrence.
The permeameter apparatus measures pressure drop, &#916;P, and the concentration of tracer (dye) exiting horizontal packed beds of armored glass for either water, air, or two-phase flow (Figures 1 and 2). Water enters through a control valve and can be routed through manual valves to any of five beds (48&#34; long, 3&#34; I.D.) with different size glass bead dumped (random) packings. The pressure drop is measured using a pressure transmitter. The water flow is measured by a differential pressure (DP, orifice) transmitter and the air flow by a dry test meter (similar to a home gas meter). The dye sample is injected upstream by an automated sampling valve. The exit concentration of the dye from a bed is measured using a UV-Vis spectrometer. Residence time distributions are calculated from the tests and compared to the predictions of theories on dispersion in packed beds. Two-phase flow will be studied in bed 5, which contains the largest particles.
<img alt="Figure 1" src="/files/ftp_upload/10431/10431fig1.jpg" /> 
Figure 1: Process and instrumentation diagram of the apparatus.
<img alt="Figure 2" src="/files/ftp_upload/10431/10431fig2.jpg" /> 
Figure 2. 3-D rendering of the apparatus. Bed #1 is at the top, bed #5 at the bottom. The water control valve is on the left (red bonnet). The DP transmitter is at the top center (blue).

填料床反应器中的单相和两相流

Source: Kerry M. Dooley and Michael G. Benton, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA
The goal of this experiment ...