CDS&E: Multi-scale, many-body simulations of near-field radiative heat transfer between micro/nanostructured materials

将热辐射有效转化为电能有可能大幅减少能源浪费和相关的环境影响，例如温室气体排放。近场热光伏发电通过由纳米间隙分隔的热发射器和光伏电池之间的热辐射产生电力。 这项新技术利用了纳米级近场辐射传热的特性，超越了宏观物体的效率极限。然而，它在工程设备中的使用需要设计师纳米结构材料来控制近场辐射传热，而这些材料的设计由于缺乏可靠、准确的计算模型而受到限制。该项目旨在推进近场辐射传热的计算模型，以实现废热回收和能量转换的新型设备。为了确保项目成果的广泛传播，计算框架将免费向公众开放。 K-12 推广活动将使用展示热光伏能源转换重要性的套件进行。该项目的目标是构思、实施和验证一个全面的计算框架，支持复杂微/纳米结构材料之间的多尺度、多体近场辐射传热模拟。计算框架基于数值精确的热离散偶极子近似。然而，目前热离散偶极子近似的实现在计算上是昂贵的，因为它需要求解大型随机方程组，因此仅限于涉及两个或三个微米/纳米尺寸物体和一个表面的模拟。该项目将通过一种新颖的、计算高效的热离散偶极近似版本来解决这一瓶颈，该近似基于系统格林函数，不需要求解随机方程组。具体来说，该项目的目标将通过完成三项任务来实现：（1）基于系统格林函数的热离散偶极近似的实现，用于近场辐射传热的多尺度、多体模拟； (2)有效介质理论适用范围的确定； (3)通过微/纳米结构材料制成的装置的近场辐射传热实验验证计算框架。该项目将填补目前主要基于有效介质理论的微纳结构材料近场辐射传热方面的关键知识空白。该项目的成果将有可能加速新型能源转换和废热回收技术的实施。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Efficient conversion of thermal radiation into electrical power has the potential to drastically reduce wasted energy and associated environmental impacts, such as greenhouse gas emission. Near-field thermophotovoltaics generate electrical power by thermal radiation between a hot emitter and a photovoltaic cell separated by a nanometer gap. This new technology exploits the properties of near-field radiative heat transfer at the nanoscale, which surpasses the efficiency limits of macroscopic objects. However, its use in engineered devices requires designer nanostructured materials to control the near-field radiative heat transfer, and the design of these materials is limited by the lack of a reliable, accurate computational models. This project seeks to advance computational modeling of near-field radiative heat transfer to enable novel devices for waste heat recovery and energy conversion. To ensure wide dissemination of the project outcomes, the computational framework will be made freely available to the public. K-12 outreach will be performed with a kit demonstrating the importance of thermophotovoltaic energy conversion. The goal of this project is to conceive, implement and validate a comprehensive computational framework enabling multi-scale, many-body near-field radiative heat transfer simulations between complex micro/nanostructured materials. The computational framework is based on the numerically exact thermal discrete dipole approximation. The current implementation of the thermal discrete dipole approximation is however computationally expensive, as it requires solution of a large stochastic system of equations, and is thus limited to simulations involving two or three micro/nanosized objects and a surface. The project will address this bottleneck via a novel, computationally efficient version of the thermal discrete dipole approximation based on system Green’s functions that do not require solving a stochastic system of equations. Specifically, the goal of this project will be fulfilled by accomplishing three tasks: (1) Implementation of the thermal discrete dipole approximation based on system Green’s functions for multi-scale, many-body simulations of near-field radiative heat transfer; (2) Determination of the limit of applicability of the effective medium theory; (3) Validation of the computational framework via near-field radiative heat transfer experiments with devices made of micro/nanostructured materials. The project will fill a critical knowledge gap in near-field radiative heat transfer of micro/nanostructured materials that is heavily based on the effective medium theory at present. The outcome of the project will potentially accelerate the implementation of novel energy conversion and waste heat recovery technologies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.