Fluids Inspired Granular Processing: Novel methods of mixing and separation

0933358麦卡锡尽管最近取得了进展，但粒子处理仍然远远落后于流体处理的同行。该提案的统一主题是采用流体处理的概念，以开发用于颗粒应用的新技术。具体地说，我们的目标是在无粘结(自由流动)材料的表面流动中混合不同的材料，以及新的颗粒分离技术。这项工作的第一个重点领域的基本假设是，通过利用流动扰动这一在流体处理方面有着悠久历史的技术，我们可以首次开发出一种限制自由流动系统中颗粒分离的通用方法，这可能是最常见和研究最充分的颗粒流方法。这种方法的关键在于认识到材料需要有限的时间才能分离，而且颗粒倾向于分离的方向总是存在的。为了利用这两个事实，人们需要以高频的方式对流动进行扰动，从而使表层反转。颗粒分离技术通常技术含量很低，通常是能源密集型(如筛分)或不环保(如泡沫浮选)或两者兼而有之。这项工作的第二个重点领域的基本假设是，我们可以基于颗粒温度驱动的分离和(颗粒)能量的非均匀分配来开发基于速率的分离技术。具体地说，我们的目标是使用振动台来构建颗粒色谱仪的模拟，该振动台提供振动能量的梯度，因此也就是颗粒温度的梯度。此外，我们计划探索颗粒状棘轮，类似于微流体研究中的布朗棘轮，因为能量的非均分将产生等同于棘轮作用于分离所需的物种依赖的扩散系数。这些流体激发的颗粒分离装置不仅应该克服传统颗粒分离技术的几个缺点，而且还将有助于在非常实际的背景下验证基于动力学理论的模型。这项工作的主要学术价值将通过促进工程和物理领域的知识和理解得到证明：1.将我们的初步混合结果扩展到概念证明阶段，成为限制各种表面主导流动中单一(密度或大小)和混合模式分离的通用方法，包括开发一套验证的实验和模拟结果，证明流动扰动对限制分离的有效性。2.建立各种颗粒处理装置无分离运行的设计启发式。3.可以作为动力学理论表达式变化的试验台的一系列实验。4.两种新的颗粒分离设备：颗粒色谱仪和颗粒棘轮装置主要的更广泛的影响将与涉及颗粒加工的各种行业的经济影响有关，对这些行业来说，混合/分离和颗粒分离对产品/收入具有重大影响。这项工作的其他更广泛的影响在于将教学和研究结合起来。这种教学/研究一体化将采取两种形式：培训两名研究生和几名本科生研究人员(重点是代表性不足的群体)，以及开发一项新的汉森K-12教师培训/伙伴计划，重点是培养弱势青年对科学的兴趣。粒子技术研究人员对实践教学的自然倾向与对当地社区弱势青年产生积极影响的愿望相结合，PI建议与学院特许学校(http://www.theacademysystem.com).)建立合作伙伴关系这所8-12年级的学校是美国唯一一所专门专注于教育受法院审判的青少年的特许学校。实践或基于探究的科学教育已被证明不仅改善了学生对科学的态度，而且还培养了更高的整体成就以及对人口背景的更平坦的反应。拟议的合作伙伴关系将包括PI和学院特许学校的教师之间的研讨会，旨在开发和/或调整适合于科学/工程教育的探究式教学模块在这种独特的学习环境中高度竞争的性质提交给计划的建议和小组建议，计划主任建议授予该建议。

0933358 McCarthy Despite recent advances, particle processing still lags significantly behind its counterpart of fluid processing. The unifying theme of this proposal is the adaption of concepts from fluid processing in order to develop novel techniques for particle applications. Specifically, we target the mixing of dissimilar materials in surface flows of cohesionless (free flowing) materials as well as novel particle separation techniques. The underlying hypothesis of the first focus area of this work is that by exploiting flow perturbations a technique with a long history in fluid processing we can develop, for the first time, a general method for limiting particle segregation in free flowing systems, perhaps the most common and well studied of granular flows. The key to this approach lies in recognizing that it takes a finite time for material to segregate and that there is always a preferred direction that particles tend to segregate. In order to exploit these two facts, one needs to perturb the flow at a high frequency and in such a way that the surface layer is inverted. Particle separations techniques are typically quite low tech and often are energy intensive (e.g., sieving) or environmentally unfriendly (e.g., froth floatation) or both. The underlying hypothesis of the second focus area of this work is that we can develop rate based separations techniques based on granular temperature driven segregation and non-equipartition of (granular) energy. Specifically, we aim to build an analog of a granular chromatograph using a shaking table that imparts a gradient in vibration energy and hence, a gradient in granular temperature. Additionally, we plan to explore granular ratchets in analogy to Brownian ratchets from microfluidic studies because non equipartition of energy will yield the equivalent of the species dependent diffusion coefficient necessary for ratcheting to function for separations. These fluids inspired particle separations devices should not only overcome several of the shortcomings of traditional particle separations techniques, but also will help to validate kinetic theory based models in a very practical context. The chief intellectual merit of this work will be evidenced through advancing knowledge and understanding across fields of engineering and physics via: 1. Expanding our preliminary mixing results past the proof of concept stage and into a general methodology for limiting both single (density or size) and mixed mode segregation in a variety of surface dominated flows, including developing a set of validating experimental and simulation results that demonstrate the utility of flow perturbations for limiting segregation. 2. Establishing design heuristics for segregation free operation of a variety of particle processing devices. 3. A series of experiments that can be used as a test bed for variations on kinetic theory expressions. 4. Two novel particle separation devices: a granular chromatograph and a granular ratchet apparatus The primary broader impacts will be related to the economic impact on the wide variety of industries that deal with particle processing for whom mixing/segregation and particle separation have dramatic product/revenue implications. Additional broader impacts of the work lie in integrating teaching and research. This teaching/research integration will take two forms: training of two graduate students and several undergraduate researchers (with emphasis on under represented groups), and the development of a novel handson K-12 teacher training/partnership program focused on building interest in science in disadvantaged youths. Coupling a particle technology researchers natural propensity for hands-on instruction with a desire to have a positive impact on the the disadvantaged youth in the local community, the PI is proposing to form a partnership with the Academy Charter School (http://www.theacademysystem.com). This 8-12 grade school is the only charter school in the US exclusively focused on educating court ejudicated youth. Hands-on or inquiry based science education has been shown to not only improve student attitudes toward science, but also to foster higher overall achievement as well as a more flat response as a function of demographic background. The proposed partnership will comprise workshop like sessions between the PI and instructors in the Academy Charter School aimed at developing and/or adapting inquiry based educational modules suitable for science/engineering education in this unique learning environment highly competitive nature of the proposals submitted to the Program and the panel recommendation, the Program Director recommends that this proposal be awarded.