Name: ice generation and the heat and mass transfer phenomena of introducing water to a cold bath of brine
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注意:有两个有毒化学品，甲醇和乙二醇，在这些实验中使用。甲醇可以在人体内被代谢以产生甲醛，然后向甲酸或甲酸盐。这些物质是有毒的中枢神经系统，甚至可能导致死亡。乙二醇可被氧化成乙醇酸，然后可以变成草酸。这可能会导致肾功能衰竭而死亡。不要喝这些化学物质。立即咨询医生，如果发生事故。 1.冷却系统注意:这是非常困难的，以保持盐水在-18℃左右，当环境温度是大约在室温下。重要的是存储乙二醇和盐水罐是公绝缘的合理大小的和，以避免多余的电力消耗，以确保最佳的系统性能。它建议在罐的大小不超过30 L。 <ol><li> 准备二次冷却液 <ol><li>倒入1升乙二醇进入二次冷却罐，罐A（基数:400毫米×200毫米，高度:350毫米）。水约0.6-0.65 L（600-650 G）添加到油箱A. </li><li>重复步骤1.1.1几次，直到有坦克A（25L）足够的液体。 </li><li>搅拌流体，使该流体是均匀的。 </li><li>开关在箱体A两个泵的全容量设置（2,500升/小时）。确保被困在换热器所有的泡沫和管道被释放。 </li><li>关掉泵，以观察是否所有气泡被释放。如果没有，重复步骤1.1.4。 </li></ol></li><li> 盐水的制备 注意:在这个例子中，22％（重量）的盐水中制备。如果需要其他浓度，补充盐分的质量也应该相应改变。参考盐水的浓度和密度值可以在页D-257的第64 个版本（1983年）中找到化学与物理 46 电子CRC手册 。 <ol><li>加入4公斤的水倒入5升的塑料烧杯中。 </li><li>测量电子秤1公斤氯化钠盐，倒入这种盐与水的烧杯中。 </li><li>搅拌混合物直至溶液澄清（ 即，不存在盐粒子或水中的气泡在溶液中可见）。 </li><li>取一个样品，〜10毫升，用10毫升的注射器的溶液。 </li><li>注入流体进入U型管密度计。 </li><li>检查在管气泡。如果有任何，注入更多的流体推他们出去。 </li><li>按"快速设置"，然后选择"密度温度。" Type在20°C，按"确定"。密度计现在将测量在该温度下的流体密度。 </li><li>按下启动并等待结果。 </li><li>密度读数与1164.00千克/ m 3的比较。 </li><li>添加更多的盐，如果读的是下面的试比较氮密度。否则加水。 </li><li>重复步骤1.2.3-1.2.10直到流体密度是正确的（1164.00公斤/米3）。 </li><li>倾该溶液成一个较大的容器中，容器A. </li><li>使用步骤1.2.1-1.2.12，使35-40大号盐水，并把容器成冷柜在-40°C。保持盐水有48-72小时，直到温度达到-19.18°C（冻结这22重量％的盐水点）。 </li></ol></li></ol> 2.冰的注射和洗水的制备<ol><li> 准备冰为水注入 <ol><li>倒入1升水到一个小容器（200×200×50毫米）。 </li><li>重复步骤2.1.1与另一容器，并放置在冷柜的两个容器在-40℃。 </li><li>保持它们在冷冻10小时或更多，以确保所有的水被冻结。 </li></ol></li><li> 准备洗涤水的冰壳 <ol><li>填有5升烧杯中以5升的水。 </li><li>补的2L烧杯用2L的水。 </li><li>放置两个烧杯放入卧式冷冻在-40℃下为8-10 h后，周围有未冻水冰包裹的厚壳。 </li><li>在3-5米/秒的速度从水龙头使用高速水射流在冰壳的顶部打开一个3厘米直径的孔。 </li><li>沥干水冰壳里面。 </li><li>把两个烧杯放回冷冻。 </li><li>如果冰壳的质量没有达到3公斤和1公斤的两个烧杯，分别重复步骤2.2.1-2.2.5，但在步骤2.2.3保持烧杯在冷冻更长。两个烧杯现在应该能够以包含2 L和1L水，分别</li></ol></li></ol> 3.水简介地位和流变控制实验<ol><li> 在卤水表面水介绍 <ol><li>从容器中倒出2升22％（重量）的冷盐水进入冰淇淋机和开关冷却装置上的铝桶。 </li><li>测量用温度计/热电偶盐水的温度（无论是K型或T型是合适的）。在实验进行，如果盐水是-15℃或更低。 </li><li>在室温下填充用自来水100ml的玻璃注射器。附上一个2毫米内径，1毫米厚，和1米长的硅胶管与注射器的前端。 </li><li>放置注射器在特定的位置，使得在注射器中的水和硅氧烷管的出口之间的头部。静水压力将挤压出来的水管。 </li><li>淹没硅胶管的一定的长度，通常为70厘米，进入盐水洗涤。 </li><li>调节注射器和管出口之间的相对位置，使得流体静压足够大以允许水离开注射器。如果管被堵塞，通过提高注射器向更高的垂直位置，UNT增加头部IL静水压力能够克服所述管内的剪切应力。 </li><li>保持管出口大致为1cm以下的盐水表面上方。 </li><li>调节浸没管的长度和注射器高度，以控制水的出口让温度，以便确定多少冰能够制造或者多少混合在盐水表面发生流速。冻结现象应现在盐水表面进行观察。请参见参考45进一步的方向。 </li></ol></li><li> 通过盐水引入水 <ol><li>重复步骤3.1.1-3.1.6。 </li><li>保持管出口处的盐水内，优选在容器的底部。 </li><li>调节浸没管的长度和注射器的高度。 </li><li>调整管出口的角度，以控制流的流变性。 </li><li>重复步骤3.2.3-3.2.4找到最好耦合流动流变和流动，可以产生最冰速率。 </li></ol></li></ol><ol><li> 制冰 <ol><li>如果有在管道中的气泡，打开箱A内的两个泵以释放气泡出乙二醇循环系统，然后关掉泵。 </li><li>开关上的三个制冷机组，并让他们运行10-16小时，以降温乙二醇溶液。 </li><li>测量用温度计/热电偶的乙二醇溶液。乙二醇的温度应在约-25℃。 </li><li>测量在容器A中的盐水的温度，以确保它是在-19℃进到步骤4.1.5之前。 </li><li>填写卤水罐，罐B，从容器中大约30升盐水和交换机上的坦克A.两个泵</li><li>测量罐A中的乙二醇如果温度低于-19℃的温度，关闭一个或多个冷却单元，以防止冰粒子的析出的热交换器外我Ñ罐B.如果温度高于预期盐水温度高，打开所有的三个冷却单元。开展在-17℃至-19℃的实验。 </li><li>放置冰从步骤2.1在两个预制块到绝缘5升的烧杯中，容器B和倒大致3升的水进入烧杯中。 </li><li>测量水的温度和由如果温度上升实验之间搅拌该混合物保持在2℃。 </li><li>填用100mL的2℃水的玻璃注射器。 </li><li>申请5-10毫升甲醇中，罐B的玻璃窗口以停止缩合和冰的形成。 </li><li>通过调节注射器和管的出口之间的相对位置，以便有一个恒定的静水压力，因此以恒定流速注入水进入盐水洗涤。约70厘米硅胶管，应在盐水被淹没。调整喷射的角度为0°，使得在向上可怕的初始水流速度ction为0米/秒。 注:注射器可以是手持或夹持到一个支架上。当盐水温度是较冷的，因为它需要更多的时间进行调整的支架，和冰可能堵塞管子手持是比较合适的。保持流动流变通过确保以恒定的流速和喷射角（0°）和通过保持冻结前沿的管出口上方大致3厘米整个实验一致。不要让流进它开始转向动荡47的区域。请参见参考45进一步的方向。 </li><li>如步骤4.2和4.3描述收集冰块。在不同温度下的盐水4.1.11 - 重复步骤4.1.8。 </li></ol></li><li> 收集制作冰块和估计有多少冰生产（干集合） <ol><li>通过按比例把一个容器（200×200×50毫米）和零读数的"打开"按钮。 </li><li>使用筛舀出冰抖落盐水。 </li><li>把这个冰在容器中。测量用的刻度冰的质量。 </li><li>冰融化后，用10毫升的注射器取样品。注射液这个样品放入密度计。 </li><li>执行步骤1.2.6-1.2.9。 </li><li>记录密度读数。 </li><li>从其密度计算净水的质量（ 即，水转化成冰的质量）使用下面的公式: <img alt="方程" src="/files/ftp_upload/55014/55014eq1.jpg" /> 哪里<img alt="方程" src="/files/ftp_upload/55014/55014eq2.jpg" />是由重量％的盐水的浓度和<img alt="方程" src="/files/ftp_upload/55014/55014eq3.jpg" />和<img alt="方程" src="/files/ftp_upload/55014/55014eq4.jpg" />分别是盐和水，群众。 </li></ol></li><li> 收集制作冰块和估计有多少冰产生（湿集合） <ol><li>填用冰壳（步骤2中的5升烧杯中。2）和室温的自来水。把它放回冷冻在-40°C。 </li><li>倒出从5升烧杯中的冰壳的水倒入2升烧杯中，当它的温度在0℃。填补了5升烧杯中。保留两个烧杯在冷冻。 </li><li>舀出在步骤4.1.8和4.1.9中产生的冰和倾200-500毫升从2升烧杯中的水到冰清洗。应用0℃的水之前，不要摇动筛。 </li><li>抖落在筛中的流体。 </li><li>重复步骤4.2.2-4.2.7。 </li></ol></li></ol>

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P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+method+of+correlating+forced+convection+heat-transfer+data+and+a+comparison+with+fluid+friction.">A method of correlating forced convection heat-transfer data and a comparison with fluid friction.</a> Trans. Am. Inst. Chem. Eng. 29, 174-210 (1933).</li><li>Colburn, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+method+of+correlating+forced+convection+heat-transfer+data+and+a+comparison+with+fluid+friction.">A method of correlating forced convection heat-transfer data and a comparison with fluid friction.</a> Int. J. Heat Mass Transfer. 7, 1359-1384 (1964).</li><li>Chilton, T. H., Colburn, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mass+Transfer+(Absorption)+Coefficients+Prediction+from+Data+on+Heat+Transfer+and+Fluid+Friction.">Mass Transfer (Absorption) Coefficients Prediction from Data on Heat Transfer and Fluid Friction.</a> Ind. Eng. Chem. 26, 1183-1187 (1934).</li><li>Friend, W. L., Metzner, A. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Turbulent+heat+transfer+inside+tubes+and+the+analogy+among+heat,+mass,+and+momentum+transfer.">Turbulent heat transfer inside tubes and the analogy among heat, mass, and momentum transfer.</a> AIChE J. 4, 393-402 (1958).</li><li>Bejan, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Constructal-theory+network+of+conducting+paths+for+cooling+a+heat+generating+volume.">Constructal-theory network of conducting paths for cooling a heat generating volume.</a> Int. J. Heat Mass Transfer. 40, 799-816 (1997).</li><li>Bejan, A., Lorente, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Constructal+theory+of+generation+of+configuration+in+nature+and+engineering.">Constructal theory of generation of configuration in nature and engineering.</a> J. Appl. Phys. 100, 041301 (2006).</li><li>Bejan, A., Lorente, S., Yilbas, B. S., Sahin, A. Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Why+solidification+has+an+S-shaped+history.">Why solidification has an S-shaped history.</a> Sci. Rep. 3, 1711 (2013).</li><li>Lake, R. A., Lewis, E. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Salt+rejection+by+sea+ice+during+growth.">Salt rejection by sea ice during growth.</a> J. Geophys. Res. 75, 583-597 (1970).</li><li>Wettlaufer, J. S., Worster, M. G., Huppert, H. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+convection+during+solidification+of+an+alloy+from+above+with+application+to+the+evolution+of+sea+ice.">Natural convection during solidification of an alloy from above with application to the evolution of sea ice.</a> J. Fluid Mech. 344, 291-316 (1997).</li><li>Paige, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stalactite+Growth+beneath+Sea+Ice.">Stalactite Growth beneath Sea Ice.</a> Science. 167, 171-172 (1970).</li><li>Dayton, P. K., Martin, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Observations+of+ice+stalactites+in+McMurdo+Sound,+Antarctica.">Observations of ice stalactites in McMurdo Sound, Antarctica.</a> J. Geophys. Res. 76, 1595-1599 (1971).</li><li>Eide, L. I., Martin, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+formation+of+brine+drainage+features+in+young+sea+ice.">The formation of brine drainage features in young sea ice.</a> J. Glaciol. 14, 137-154 (1975).</li><li>Martin, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ice+stalactites:+comparison+of+a+laminar+flow+theory+with+experiment.">Ice stalactites: comparison of a laminar flow theory with experiment.</a> J. Fluid Mech. 63, 51-79 (1974).</li><li>Jeffs, K., Attenborough, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Frozen Planet: Episode 5 'Winter'. , (2011).</li><li>Fothergill, A., Berlowitz, V., Attenborough, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ch.+Winter:+Life+closes+down.">Ch. Winter: Life closes down.</a> in Frozen Planet: A World Beyond Imagination. , (2011).</li><li>Yun, X., 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=Ice+formation+in+the+subcooled+brine+environment.">Ice formation in the subcooled brine environment.</a> Int. J. Heat Mass Transfer. 95, 198-205 (2016).</li><li>Weast, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> CRC Handbook of Chemistry and Physics. 64, 257-258 (1983).</li><li>Bejan, A., Lage, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Prandtl+Number+Effect+on+the+Transition+in+Natural+Convection+Along+a+Vertical+Surface.">The Prandtl Number Effect on the Transition in Natural Convection Along a Vertical Surface.</a> J. Heat Transfer. 112, 787-790 (1990).</li></ol>

作者什么都没有透露。

用盐水作为二次制冷剂冰生成的过程涉及的热与质量传递的组合。当热传递较大，则水之前冰形成具有与散装流体混合的机会。据观察，当存在引入的水和静止本体盐水之间的相对运动（即盐水内注入水）时，流程有助于传热，并鼓励冰以形成迅速。然而，当存在太多的湍流中的流动，可以产生没有冰。这种技术的最大限制是盐水的混合和稀释。盐水量将继续作为进程继续上升。因此，使?...

<html>冰浆在工业中广泛使用，并且一种特别成功的应用是冰清管技术1，2。相比于常规的泡沫和固体猪，冰猪可以在很长的距离，通过复杂的拓扑行进的，因为液相的润滑效果和它的凝固点的，因为一些冰晶融化3，4，5的高度。即使猪被卡住，可以简单地等待冰浆熔化并在稍后继续清洁过程。管道清洗的这种方法是便宜的，并易于使用。 冰馏分起着冰猪的性能起关键作用。为了测量冰分数，可以使用一个壶煮（法国媒体），以确定是否冰浆是足够厚6，"&gt; 7，一个高的壶煮冰馏分，通常为80％时，进行冰清管时需要。网上冰分数检测最近的研究表明，电磁和超声波适于作业8，9，10，11。 冰猪通常是由一个刮面制冰机从5％（重量）NaCl溶液（盐水）制成。它也是在工业制造冰浆的主要方式。这种类型的制冰机的冻结水或盐水在冷金属表面，通常是光滑的316不锈钢表面，然后循环剪冰粒关闭。液体-金属界面是非常复杂的，并通过广泛的那些对制冰12基本因素的影响。非金属和水之间的接口是非常不同的，一个特别有趣的例子是高岭石。该Kaolinite -水界面是特殊的，因为没有一个有利的冰结构邻近于固体表面，而是鼓励冰状氢键团簇形成在它的13顶，14两性基底流体的层。制作冰猪的另一种方式，而需要高浓度盐水同时加入粉碎预制冰块。对于此方法，所述制冷系统能以高得多的蒸发温度运行，因为没有降凝剂（FPD）之前被冰的形成增加;它因此认为更有效的，由于对于给定的冷却负荷15，16，17中的降低压缩率和减少功耗。 还有另外两个冰制作方法:从生产过冷的水冰，并把制冷剂与水直接接触<sup类="外部参照"&gt; 18，19。过冷方法涉及干扰亚稳定过冷水以产生冰核和生长。这种方法的最大的问题是不希望的冰的形成，可以阻止该系统。因为制冷剂也不润滑油无论是在最终产品的冰都希望直接接触的方法被认为不适合冰清管。 冰的形成需要的热与质量传递由于在过程中产生的熔化潜热。它首先是由Osborn的雷诺兹发现在1874年该热质在气体中的运输是强耦合，并且可以在类似的数学式20来表示。这项工作形成声势，热和质量的流体传递的主题开拓纸和被转载多次21,22。这个题目，然后通过一个研究他人的数目，从既分析和经验方法，对气体，液体，熔融金属23，24，25，26，27，28，29，30，31，32，33。除了热与质量传递，流体需要成核位点，其中树枝状冰增长可以开发。一个现代的洞察冰晶的生长采用构形法，由Adrian Bejan开发，解释为什么冰生长在这种方式34，35，36。 冰的形成在盐水不同于在纯水中非常不同，由于盐的存在。首先，<html>盐变化的流体的热力学和按压其冰点。其次，盐可以不溶解在冰基质（除hydrohalite，当温度达到共晶点，这只能形成），并且当冰开始增长它被拒绝到散装流体。盐的排斥海冰和冰都在实验室中37，38研究发现。由于拒绝高浓度盐水的温度大大低于海水的冰点，因为它下降时，冰生长在流动盐水和静态散装流体之间的界面。这些冰的钟乳石，也叫brinicles，在麦克默多海峡，南极洲被首次发现并进行了实验39，40，41，42研究。 2011年，BBC摄制的冰冻星球系列brinicles形成"外部参照"&gt; 43，44。 在我们的实验室中，人们发现，通过反转时水被引入到冷盐水浴中流动的静止流体，水可以转变成冰的正确条件45下。结果发现，其中，被引入的水的位置，流动流变学，和盐水洗涤温度和浓度是影响多少冰如何可以产生的所有的关键因素。本研究的总体目标是调查，如果一个制冰机可以通过这一机制被开发，以产生冰浆，考虑到提高的蒸发器的温度和液体到液体传热的高速率可以提高能源的使用效率。本文股份实验的关键方面。

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ice generation and the heat and mass transfer phenomena of introducing water to a cold bath of brine

我们证明用于在过冷盐水环境中的热与质量传递的冷冻现象和研究的方法。我们的试验表明，在适当的条件下，可以在水被引入到冷盐水浴来制造冰。以制造冰的形式，除了具有盐水和水混合，传热的速率必须绕过传质。当在微小液滴的盐水表面的形式被引入的水，热和质量传递的方式是通过扩散。浮力从下方与盐水混合停止水，但随着冰成长厚，它减慢传热率，使得冰更难以成长的结果。当在流动的形式盐水内引入水，许多因素被发现影响多少冰能形成。盐水洗涤温度和浓度，它们的热与质量传递的驱动力，分别可影响水 - 冰转换拉提O;低浴温及盐水浓度鼓励更多的冰形成。流动流变性，它可以直接影响同时传热和传质系数，也是一个关键的因素。此外，流动流变学变化与散装流体的流动的接触面积。

图1比较的水在盐水表面水通过盐水注入引入的影响。在"冰盖"的情况下，形成的冰是固体，因为水不与散装流体混合得多。两种流体之间的温度和密度差异对水产生浮力，防止它们混合。两种流体是静态的（ 即，该传热比质量大得多;钪≈500，镨≈10，以及乐≈50），因此，冰能形成容易。既没有形成在这个实验糊状层也不盐排斥。一旦冰成长厚，它会?...

Watch this Scientific Journal Video about Ice Generation and the Heat and Mass Transfer Phenomena of Introducing Water to a Cold Bath of Brine at JoVE.com

Ice Generation and the Heat and Mass Transfer Phenomena of Introducing Water to a Cold Bath of Brine

在这里，我们提出了一个协议，当水被引入到盐水的冷浴，作为二次制冷剂，在一定温度范围内大大低于水的凝固点以证明冰的生成。它可以用作制造用于工业冰的另一种方法。

冰生成和传热传质现象将水引入到盐水冷水浴

We demonstrate a method for the study of the heat and mass transfer and of the freezing phenomena in a subcooled brine environment. Our experiment showed ...

ice-generation-heat-mass-transfer-phenomena-introducing-water-to-cold

Universidad de Cartagena UDEC

Research

Education

JoVE Core

JoVE Journal

Physics

Engineering

Unit 1

Temperature and Heat

SCIENTISTS IN ACTION

13.8K 次观看.  University of Bristol. 在这里，我们提出了一个协议，当水被引入到盐水的冷浴，作为二次制冷剂，在一定温度范围内大大低于水的凝固点以证明冰的生成。它可以用作制造用于工业冰的另一种方法。 

视频: Ice Generation and the Heat and Mass Transfer Phenomena of Introducing Water to a Cold Bath of Brine

Reservoir Condition Pore-scale Imaging of Multiple Fluid Phases Using X-ray Microtomography

X-ray microtomography was used to image, at a resolution of 6.6 &#181;m, the pore-scale arrangement of residual carbon dioxide ganglia in the pore-space of a carbonate rock at pressures and temperatures representative of typical formations used for CO2 storage. Chemical equilibrium between the CO2, brine and rock phases was maintained using a high pressure high temperature reactor, replicating conditions far away from the injection site. Fluid flow was controlled using high pressure high temperature syringe pumps. To maintain representative in-situ conditions within the micro-CT scanner a carbon fiber high pressure micro-CT coreholder was used. Diffusive CO2 exchange across the confining sleeve from the pore-space of the rock to the confining fluid was prevented by surrounding the core with a triple wrap of aluminum foil. Reconstructed brine contrast was modeled using a polychromatic x-ray source, and brine composition was chosen to maximize the three phase contrast between the two fluids and the rock. Flexible flow lines were used to reduce forces on the sample during image acquisition, potentially causing unwanted sample motion, a major shortcoming in previous techniques. An internal thermocouple, placed directly adjacent to the rock core, coupled with an external flexible heating wrap and a PID controller was used to maintain a constant temperature within the flow cell. Substantial amounts of CO2 were trapped, with a residual saturation of 0.203 &#177; 0.013, and the sizes of larger volume ganglia obey power law distributions, consistent with percolation theory.

We present a methodology for the imaging of multiple fluid phases at reservoir conditions by the use of x-ray microtomography. We show some representative results of capillary trapping in a carbonate rock sample.

多重流体相储层孔隙条件级成像使用X射线微断层

X-ray microtomography was used to image, at a resolution of 6.6 &#181;m, the pore-scale arrangement of residual carbon dioxide ganglia in the pore-space ...

科研

工程学

Evolution of Staircase Structures in Diffusive Convection

Diffusive convection (DC) occurs when the vertical stratified density is controlled by two opposing scalar gradients that have distinctly different molecular diffusivities, and the larger- and smaller- diffusivity scalar gradients have negative and positive contributions for the density distribution, respectively. The DC occurs in many natural processes and engineering applications, for example, oceanography, astrophysics and metallurgy. In oceans, one of the most remarkable features of DC is that the vertical temperature and salinity profiles are staircase-like structure, composed of consecutive steps with thick homogeneous convecting layers and relatively thin and high-gradient interfaces. The DC staircases have been observed in many oceans, especially in the Arctic and Antarctic Oceans, and play an important role on the ocean circulation and climatic change. In the Arctic Ocean, there exist basin-wide and persistent DC staircases in the upper and deep oceans. The DC process has an important effect on diapycnal mixing in the upper ocean and may significantly influence the surface ice-melting. Compared to the limitations of field observations, laboratory experiment shows its unique advantage to effectively examine the dynamic and thermodynamic processes in DC, because the boundary conditions and the controlled parameters can be strictly adjusted. Here, a detailed protocol is described to simulate the evolution process of DC staircase structure, including its generation, development and disappearance, in a rectangular tank filled with stratified saline water. The experimental setup, evolution process, data analysis, and discussion of results are described in detail.

Diffusive convection (DC) widely occurs in natural processes and engineering applications, characterized by a series of staircases with homogeneous convecting layers and stratified interfaces. An experimental procedure is described to simulate the evolution process of the DC staircase structure, including the generation, development and disappearance, in a rectangular tank.

扩散对流中阶梯结构的演化

Diffusive convection (DC) occurs when the vertical stratified density is controlled by two opposing scalar gradients that have distinctly different ...

环境科学

Pool-Boiling Heat-Transfer Enhancement on Cylindrical Surfaces with Hybrid Wettable Patterns

In this study, pool-boiling heat-transfer experiments were performed to investigate the effect of the number of interlines and the orientation of the hybrid wettable pattern. Hybrid wettable patterns were produced by coating superhydrophilic SiO2 on a masked, hydrophobic, cylindrical copper surface. Using de-ionized (DI) water as the working fluid, pool-boiling heat-transfer studies were conducted on the different surface-treated copper cylinders of a 25-mm diameter and a 40-mm length. The experimental results showed that the number of interlines and the orientation of the hybrid wettable pattern influenced the wall superheat and the HTC. By increasing the number of interlines, the HTC was enhanced when compared to the plain surface. Images obtained from the charge-coupled device (CCD) camera indicated that more bubbles formed on the interlines as compared to other parts. The hybrid wettable pattern with the lowermost section being hydrophobic gave the best heat-transfer coefficient (HTC). The experimental results indicated that the bubble dynamics of the surface is an important factor that determines the nucleate boiling.

Pool-boiling heat-transfer experiments were carried out to observe the effects of hybrid wettable patterns on the heat-transfer coefficient (HTC). The parameters of investigation are the number of interlines and the pattern orientation of the modified wettable surface.

在圆柱面池沸腾传热强化与混合可湿性模式

In this study, pool-boiling heat-transfer experiments were performed to investigate the effect of the number of interlines and the orientation of the ...

Near-Infrared Temperature Measurement Technique for Water Surrounding an Induction-heated Small Magnetic Sphere

A technique to measure the temperature of water and non-turbid aqueous media surrounding an induction-heated small magnetic sphere is presented. This technique utilizes wavelengths of 1150 and 1412 nm, at which the absorption coefficient of water is dependent on temperature. Water or a non-turbid aqueous gel containing a 2.0-mm- or 0.5-mm-diameter magnetic sphere is irradiated with 1150 nm or 1412 nm incident light, as selected using a narrow bandpass filter; additionally, two-dimensional absorbance images, which are the transverse projections of the absorption coefficient, are acquired via a near-infrared camera. When the three-dimensional distributions of temperature can be assumed to be spherically symmetric, they are estimated by applying inverse Abel transforms to the absorbance profiles. The temperatures were observed to consistently change according to time and the induction heating power.

A technique utilizing wavelengths of 1150 and 1412 nm to measure the temperature of water surrounding an induction-heated small magnetic sphere is presented.

感应加热小磁球周围水近红外测温技术

A technique to measure the temperature of water and non-turbid aqueous media surrounding an induction-heated small magnetic sphere is presented. This ...

Proof-of-Concept for Gas-Entrapping Membranes Derived from Water-Loving SiO2/Si/SiO2 Wafers for Green Desalination

Desalination through direct contact membrane distillation (DCMD) exploits water-repellent membranes to robustly separate counterflowing streams of hot and salty seawater from cold and pure water, thus allowing only pure water vapor to pass through. To achieve this feat, commercial DCMD membranes are derived from or coated with water-repellent perfluorocarbons such as polytetrafluoroethylene (PTFE) and polyvinylidene difluoride (PVDF). However, the use of perfluorocarbons is limiting due to their high cost, non-biodegradability, and vulnerability to harsh operational conditions. Unveiled here is a new class of membranes referred to as gas-entrapping membranes (GEMs) that can robustly entrap air upon immersion in water. GEMs achieve this function by their microstructure rather than their chemical make-up. This work demonstrates a proof-of-concept for GEMs using intrinsically wetting SiO2/Si/SiO2 wafers as the model system; the contact angle of water on SiO2 is &#952;o &#8776; 40&#176;. Silica-GEMs had 300 &#956;m-long cylindrical pores whose diameters at the (2 &#956;m-long) inlet and outlet regions were significantly smaller; this geometrically discontinuous structure, with 90&#176; turns at the inlets and outlets, is known as the &#34;reentrant microtexture&#34;. The microfabrication protocol for silica-GEMs entails designing, photolithography, chrome sputtering, and isotropic and anisotropic etching. Despite the water loving nature of silica, water does not intrude silica-GEMs on submersion. In fact, they robustly entrap air underwater and keep it intact even after six weeks (&#62;106 seconds). On the other hand, silica membranes with simple cylindrical pores spontaneously imbibe water (&#60; 1 s). These findings highlight the potential of the GEMs architecture for separation processes. While the choice of SiO2/Si/SiO2 wafers for GEMs is limited to demonstrating the proof-of-concept, it is expected that the protocols and concepts presented here will advance the rational design of scalable GEMs using inexpensive common materials for desalination and beyond.

Proof-of-Concept for Gas-Entrapping Membranes Derived from Water-Loving SiO2/Si/SiO2 Wafers for Green Desalination

Presented here is a stepwise protocol for realizing gas-entrapping membranes (GEMs) from SiO2/Si wafers using integrated circuit microfabrication technology. When silica-GEMs are immersed in water, the intrusion of water is prevented, despite the water-loving composition of silica.

气体夹膜的概念验证，源自爱水的SiO 2/Si/SiO2晶圆，用于绿色海水淡化

Desalination through direct contact membrane distillation (DCMD) exploits water-repellent membranes to robustly separate counterflowing streams of hot and ...

Measuring Electrical Conductivity to Study the Formation of Brines Under Martian Conditions

This paper describes a protocol to design experiments to study the formation of brines under Martian conditions and monitor the process with electrical conductivity measurements. We used the Engineering Qualification Model (EQM) of Habitability: Brines, Irradiation, and Temperature (HABIT)/ExoMars 2022 instrument for the experiment setup but we provide a brief account of constructing a simple and inexpensive electrical conductivity measurement setup. The protocol serves to calibrate the electrical conductivity measurements of the salt deliquescence into brine in a simulated Martian environment. The Martian conditions of temperature (-70 &#176;C to 20 &#176;C), relative humidity (0% to 100%) and pressure (7 - 8 mbar) with carbon-dioxide atmosphere were simulated in the SpaceQ Mars simulation chamber, a facility at the Lule&#229; University of Technology, Sweden. The hydrate form of the known amount of salt accommodated between a pair of electrodes and thus the electrical conductivity measured depends predominantly on its water content and the temperature and relative humidity of the system. Electrical conductivity measurements were carried out at 1 Hz while exposing salts to a continuously increasing relative humidity (to force transitioning through various hydrates) at different Martian temperatures. For demonstration, a day-night cycle at Oxia Planum, Mars (the landing site of ExoMars 2022 mission) was recreated.

The objective of the protocol is to monitor the hydration of salts and the brine formation process. Electrical conductivity is used as the measurement technique. The experiments are performed in a simulated Martian environment of temperature, relative humidity and carbon-dioxide atmosphere.

This paper describes a protocol to design experiments to study the formation of brines under Martian conditions and monitor the process with electrical ...

化学

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

Conducting Reactions Below Room Temperature

Source: Laboratory of Dr. Dana Lashley - College of William and Mary
Demonstration by: Matt Smith
When new bonds are formed in the course of a chemical reaction, it requires that the involved species (atoms or molecules) come in very close proximity and collide into one another. The collisions between these species are more frequent and effective the higher the speed at which these molecules are moving. A widely used rule of thumb, which has its roots in the Arrhenius equation1, states that raising the temperature by 10 K will approximately double the rate of a reaction, and raising the temperature by 20 K will quadruple the rate:
(1) <img alt="Equation 1" src="/files/ftp_upload/10224/10224eq1.jpg" />
Equation (1) is often found in its logarithmic form:
(2) <img alt="Equation 2" src="/files/ftp_upload/10224/10224eq2.jpg" />
where k is the rate of the chemical reaction, A is the frequency factor (relating to frequency of molecular collisions), Ea is the activation energy required for the reaction, R is the ideal gas constant, and T is the temperature at which the reaction is taking place.
A higher temperature therefore means a reaction is completed much faster. Nonetheless, in some cases it is desirable to carry out reactions at low temperatures, in spite of the lowering effect on the rate of the reaction. A few scenarios in this regard are elaborated upon further below.
When it is useful to run a reaction below room temperature, chemists use cooling baths to maintain a certain temperature or temperature range. Reactions are cooled down to a desired temperature by placing the reaction flask inside an appropriate cooling bath. The reagents in the reaction never come in direct contact with the chemicals in the cooling bath. The cooling bath may consist of a single cryogenic (cooling) component (such as ice, dry ice, or liquid nitrogen) or may be a mixture of the cryogenic component with a certain solvent and/or an additive salt. The purpose of the solvent is to effectively transfer temperature of the cooling agent to the reaction flask, and the purpose of the additive is to lower (or depress) the freezing point of the mixture. (Note that it is possible for a substance to be both a solvent and an additive.)

进行室温下反应

Source: Laboratory of Dr. Dana Lashley - College of William and Mary
Demonstration by: Matt Smith
When new bonds are formed in the course of a chemical ...

教育

JoVE Science Education

有机化学

Quenching and Boiling

Source: Alexander S Rattner, Sanjay Adhikari, and Mahdi Nabil; Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA
Controlled heating followed by rapid cooling is an important element of many materials processing applications. This heat-treating procedure can increase material hardness, which is important for cutting tools or surfaces in high wear environments. The rapid cooling stage is called quenching, and is often performed by immersing materials in a fluid bath (often water or oil). Quenching heat transfer can occur due to forced convection - when the action of rapidly moving material through coolant drives the heat transfer process, and due to free convection - when the reduced density of hot fluid near the material surface causes buoyancy-driven circulation and heat transfer. At high material temperatures, the coolant can boil, leading to increased heat transfer effectiveness. However, when extremely hot materials are quenched, they can be blanketed in relatively low thermal conductivity coolant vapor, leading to poor heat transfer.
In this experiment, quenching heat transfer will be measured for a heated copper cylinder, which is representative of small heat-treated parts. The transient sample temperature profile will be measured during quenching and compared with theoretical results for free convection heat transfer. Boiling phenomena will also be investigated qualitatively.

Quenching, Boiling, Convection and Nusselt Number

淬火和沸腾

Source: Alexander S Rattner, Sanjay Adhikari, and Mahdi Nabil; Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, ...

机械工程

Evaluating the Heat Transfer of a Spin-and-Chill

Source: Michael G. Benton and Kerry M. Dooley, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA
The Spin-and-Chill uses heat transfer and fluid flow fundamentals to chill beverages from room temperature to 38 &#176;F in as little as 2 min. It would take a refrigerator approximately 240 min and an ice chest approximately 40 min to achieve an equivalent temperature change. This is accomplished Spin and Chill by spinning a can or bottle at up to 500 rpm, which creates little or no foaming.
In this experiment, the efficacy of spinning a cylinder (i.e., soda can) at high speeds to cool a soft drink will be evaluated. Operational parameters, such as rpm and spin time, will be varied to assess their effect on heat transfer, and the heat transfer coefficient will be calculated using a lumped parameter model.

Convective Spin-and-Chill Heat Transfer: Lumped Parameter Model

旋转和寒意

Source: Michael G. Benton and Kerry M. Dooley, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA
The Spin-and-Chill uses ...