Thermal Transport in Nano-Enhanced Phase Change Materials

0931507 Fleischer相变材料（PCM）用于在瞬态加热过程中吸收和释放热能。相变材料已成功地用于小规模的太阳能储存、节能建筑材料和冷却便携式电子产品。然而，在许多较大的系统中，大多数PCM的低热导率导致PCM质量的差的利用。 最近，已经开发出具有嵌入式低成本石墨纳米纤维（GNF）的纳米增强PCM，其特征在于大的热导率。 独特的纳米纤维是使用催化分解工艺合成的，并沿纤维轴沿着呈同心基面的形式。 初步结果表明，当混合到PCM中时，纳米纤维改善了PCM的热性能。本研究考察了纳米增强PCM在熔融和固化过程中热传输的基本性质，（1）用于建筑材料，热界面材料以及其他薄膜应用的薄层（0.5 mm至5 mm），以及（2）用于太阳能存储，电子热管理和其他高功率能量系统的较厚层（20 mm至200 mm）。智力优势：负责观察到的纳米增强PCM的热性能的改善的基本能量传输机制将被确定。计算研究将通过应用分子动力学（MD）建模各种不同的风格进行。MD模型将用于预测不同纤维类型中能量传输的性质，并表征单根纤维的热导率。 将进行涉及特定基质配置的随机模拟，以确定纤维类型如何影响纳米增强型相变材料的热性能。将进行涉及嵌入不同类型纳米颗粒的相变材料的实验，以直接比较每种纳米颗粒类型对相变材料有效热导率的影响。这提供了一个基础，GNF对有效热增强的影响可以与其他更昂贵的纳米颗粒所带来的影响进行比较。更广泛的影响：该项目涉及通过传统的会议和期刊出版物以及通过nanoHUB和thermalHUB等在线社区传播结果。 该项目为几名本科生和研究生提供了研究机会。这项研究将通过新的和现有的纳米级行为课程纳入维拉诺瓦大学机械工程和化学工程系的课程。最后，PI将与维拉诺瓦工程学院V.E.S.T.E.D.合作。该学院为有风险的初中和高中学生和当地中学的外展人员提高数学、科学、技术和工程方面的学术成就。

0931507FleischerPhase Change Materials (PCMs) are used to absorb and release thermal energy during transient heating. PCMs have been used successfully at small scales for solar energy storage, in energy efficient building materials, and in cooling portable electronics. In many larger systems, however, the low thermal conductivity of most PCMs results in poor utilization of the PCM mass. Recently, a nanoenhanced PCM with embedded, low cost graphite nanofibers (GNF) characterized large thermal conductivities, has been developed. The unique nanofibers are synthesized using a catalytic decomposition process and take the form of concentric basal planes along the fiber axis. Preliminary results have shown that, when blended into a PCM, the nanofibers improve thermal performance of the PCM. This research examines the fundamental nature of thermal transport in nanoenhanced PCMs during melting and solidification in (1) thin layers (0.5 mm to 5 mm) for use in building materials, thermal interface materials as well as other thin film applications, and in (2) thicker layers (20 mm to 200 mm) for solar energy storage, electronics thermal management and other high power energy systems. Intellectual Merit: The fundamental energy transport mechanisms responsible for the observed improvement in thermal performance of the nanoenhanced PCM will be determined. Computational research will be conducted by applying molecular dynamics (MD) modeling to various nanofiber styles. The MD model will be used to predict the nature of energy transport in the different fiber styles, and characterize the thermal conductivity of a single fiber. Stochastic simulations involving specific matrix configurations will be conducted to determine how the fiber styles affect the thermal performance of the nanoenhanced PCMs.Experiments involving PCMs that are embedded with different types of nanoparticles will be conducted to allow direct comparison of the influence of each nanoparticle type on the PCMs effective thermal conductivity. This provides the basis for which the influence of GNFs on the enhancement of the effective thermal may be compared to that brought about by other more expensive nanoparticles.Broader Impact: This project involves dissemination of results through both traditional conference and journal publication, as well as by way of online communities such as nanoHUB and thermalHUB. The project provides research opportunities for several undergraduate and graduate students. The research will be integrated into the curricula of both the mechanical engineering and chemical engineering departments at Villanova University through new and existing courses in nanoscale behavior. Finally, the PIs will partner with the Villanova College of Engineerings V.E.S.T.E.D. Academy which promotes academic achievement in mathematics, science, technology, and engineering for at risk middle and high school students and outreach at local middle schools.