纳米强化相变蓄热材料关键热物性与固液相变传热特性的微观调控机理研究

Introduction of highly-conductive nanostructured fillers to form composite phase change metarials (PCMs) is a promising approach to enhancing the thermal conductivity of conventional PCMs. This project aims at preparing nanostructure-enhanced PCMs (NEPCM) with emerging carbon-based nanostructured materials, and observing and improving the stability of the prepared NEPCM through physical and chemical processing stratigies. In an effort to elucidate the microscale mechanisms of modified thermophysical properties and solid-liquid phase change of NEPCM due to the presence of carbon-based enhancers, it is also proposed to measure the important thermophysical properties of the prepared NEPCM at both solid and liquid phases, including thermal conductivity, specific heat capacity, viscosity, latent heat of fusion, and melting point, etc, and to investigate, both experimentally and numerically, the solid-liquid phase change (melting and solidification) heat transfer of the NEPCM. The results of this project will be in the form of abundant data on important thermophysical properties of the prepared NEPCM, and will reveal the effects of material, shape, clustering, and loading of the carbon-based nanostructured enhancers on the thermophysical properties and solid-liquid phase change heat transfer of NEPCM, providing reference data and scientific evidence on the utilization of such emerging PCMs in real-world applications. Moreover, the outcome of this project will be supplemental to the existing fundamental studies of multiphase heat transfer such as thermal transport in nanofluids and nanocomposites, as well as solid-liquid phase change heat transfer.

利用高导热的纳米尺度材料作为添加剂形成复合相变蓄热材料是对传统相变蓄热材料进行导热强化的有效途径。本项目拟采用新兴的碳纳米材料为强化剂，制备一系列具有不同相变温度范围的纳米强化相变蓄热材料，通过实验方法观测并利用物理和化学方法提高其稳定性。测试所制备复合相变蓄热材料在固液两态时的多种关键热物性（导热系数、比热容、粘度、相变潜热和相变温度等），利用可视化实验和数值模拟方法研究其固液相变（熔化和凝固）传热过程，分析纳米强化剂对热物性和固液相变传热特性的微观调控机理。通过本项目的研究，可以获得大量纳米强化相变蓄热材料的关键热物性数据，揭示其热物性和固液相变传热特性随碳纳米强化剂的材料、形态、团聚行为和添加量的变化规律，为该种新型相变蓄热材料的工程应用提供参考数据和科学依据。本项目的研究内容也是对现有纳米流体和纳米复合材料热输运以及固液相变传热等多相传热学基础研究工作的有益补充。

利用高导热的纳米尺度材料作为添加剂形成复合相变蓄热材料是对传统相变蓄热材料进行导热强化的有效途径。本项目采用了新兴的碳纳米材料作为强化剂，制备了一系列具有不同相变温度范围的纳米强化相变蓄热材料、其中，纳米材料包括碳纳米管、石墨填料、石墨烯、纳米银等，而相变材料基体包括水、石蜡、醇类等，并通过物理方法来强化纳米颗粒在相变材料中的分散性，主要采用的是超声振荡法。在完成复合相变材料的制备后，对复合相变材料在固、液两相是的多种关键热物性进行了测试，其中包括导热系数、比热、粘度、相变潜热以及相变温度，并利用可视化实验的方法，研究了复合相变材料的熔化和凝固过程，并综合分析了纳米强化剂对热物性和固液相变传热特性的微观调控机理。本项目获得了大量纳米强化相变蓄热材料的热物性数据，揭示了热物性和固液相变传热特性纳米强化剂的材料、形态、团聚行为以及添加量的变化规律，为新型相变蓄热材料的工程应用提供了科学依据。