Collaborative Research: Thermally Actuated Pumping Mechanism During Boiling on an Asymmetrically Structured Surface

0854503Narayanan这是俄勒冈州立大学和奥本大学的研究人员在相变强化传热的一般领域的合作研究和教育计划。研究的目的是描述在沸腾过程中被动施加的不对称力对气泡的影响。这种不对称性是通过使用具有重复棘轮结构的表面和位于其一侧的锥形凹腔来产生的。假设有几个棘轮，这种局部不对称运动可以转化为净流体泵送。该项目的主要目标是：(1)使用一套非侵入性成像方法确定随时间变化的气泡直径和频率、液体和气泡速度以及时间和空间分辨的表面温度；(2)基于从上述成像实验获得的信息改进初步模型；(3)对照大量棘轮的全球测量来验证模型，这些棘轮将被建立沸腾曲线，以及(4)将研究成果整合到现有多所大学的电子学热管理课程的新模块中。智能优点：该增强技术可应用于反向表面的热传递和空间热管理。所提出的实验方法提供了沸腾流动中的流场和温度场的详细估计，这将对模型者有用。拟议的分析将通过在不同取向和过冷度下进行实验，并使用两种性质不同的流体来突出重要的力。更广泛的影响：教育活动将包括将项目成果以模块的形式整合到现有的、过去由NSF资助的电子热管理现场互联网多校园课程中，并将俄勒冈州立大学作为新的合作伙伴。在第二年年底，DC-9微重力飞行实验计划作为NASA同时拨款的一部分。几名高年级本科生将参与这个实验的设计和最终测试。奥本大学的AT&amp；T；少数族裔工程项目学生也将与俄亥俄州立大学的本科生密切合作。一名有前途的高中生，通过俄勒冈州范围内的科学和工程学徒计划，将参与实验设计和测试。

0854503NarayananThis is a collaborative research and educational program between investigators at Oregon State University and Auburn University in the general area of phase-change heat transfer enhancement. The research goal is to characterize the effect of a passively imposed asymmetric force on a bubble during the boiling process. Such asymmetry is created by the use of a surface with repeated ratchet structures and pyramidal reentrant cavities located on one of its sides. The hypothesis is that with several ratchets, this local asymmetric motion can be translated to a net fluid pumping. Educational activities aim to provide a synergy between research and education, as well as between several universities.The main objectives of the project are to: (1) Determine, using a suite of non-intrusive imaging methods, time-varying bubble diameters and frequencies, liquid and bubble velocities, and temporally- and spatially- resolved surface temperatures, (2) Refine preliminary models based on information obtained from the above imaging experiments, (3) Validate the model against global measurements of a large-array of ratchets, for which boiling curves will be established, and (4) Integrate research findings into a new module in an existing multi-University Electronics Thermal Management course.Intellectual Merit: The enhancement technique can be applied to heat transfer from adversely oriented surfaces and in space thermal management. The proposed methods of experimentation present a detailed estimation of flow and temperature field in boiling flows that will be useful to modellers. The proposed analyses will highlight forces of importance by performing experiments under different orientations and subcooling levels, and with two fluids of contrasting properties. Passive methods of heat transfer enhancement are important in a broader context of energy efficiency.Broader Impact: Educational activities will include integration of the project results in the form of a module into an existing, past-NSF funded Electronics Thermal Management live-internet multi-campus course and will incorporate Oregon State University as a new partner. At the end of year 2, a DC-9 microgravity flight experiment is planned as a part of a concurrent grant from NASA. Several senior undergraduate students will take part in the design and eventual testing of this experiment. An AT&T-Minority-Engineering-Program student at Auburn University will also be working closely with OSU undergraduate students. One promising high-school student, through the Oregon-state-wide Apprenticeship in Science and Engineering Program, will be involved in experiment design and testing.