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

将热辐射有效地转化为电能有可能大大减少浪费的能源和相关的环境影响，如温室气体排放。近场热光电转换器通过热发射器和由纳米间隙隔开的光伏电池之间的热辐射来产生电力。 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，其在工程设备中的使用需要设计者纳米结构材料来控制近场辐射传热，并且这些材料的设计受到缺乏可靠、准确的计算模型的限制。该项目旨在推进近场辐射传热的计算建模，以实现废热回收和能量转换的新型设备。为确保广泛传播项目成果，将向公众免费提供计算框架。K-12外展将使用一个工具包来展示热光伏能量转换的重要性。该项目的目标是构思，实施和验证一个全面的计算框架，使复杂的微/纳米结构材料之间的多尺度，多体近场辐射传热模拟。计算框架是基于数值精确的热离散偶极子近似。然而，热离散偶极近似的当前实现在计算上是昂贵的，因为它需要求解大型随机方程组，并且因此限于涉及两个或三个微/纳米尺寸的物体和表面的模拟。该项目将通过一种新的，计算效率高的版本的热离散偶极子近似的基础上系统绿色的功能，不需要解决一个随机系统的方程。具体而言，本计画的目标将透过完成三项工作来达成：（1）以系统绿色函数为基础的热离散偶极近似，应用于近场辐射热传导的多尺度、多体模拟：（2）确定有效介质理论的适用范围;（3）通过使用由微/纳米结构材料制成的装置的近场辐射传热实验来验证计算框架。该项目将填补目前基于有效介质理论的微/纳米结构材料近场辐射传热的关键知识空白。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知识价值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.