Computational methods for analysis and optimization of solar thermal energy collection and storage technologies

全球对能源的需求继续迅速增加，尽管能源生产所排放的温室气体对环境构成日益紧迫的威胁。 虽然可再生能源部门近年来大幅增长，目前占能源供应总量的14%，但为了实现温室气体排放的新目标，必须保持这种增长。 目前大部分可再生能源组合由水电、生物燃料和废物组成，而地热、太阳能、风能和热能仍占总能源供应的不到2%。 太阳能的相对缺乏特别令人感兴趣，因为太阳向地球提供的能量比满足社会能源需求所需的能量多出许多倍。 拟议的研究计划侧重于开发计算工具，以设计和优化更好的捕获和存储太阳能的设备。 太阳热能只能在白天使用，这是可能限制其广泛使用的一个关键因素。 与使用电池存储电能类似，热能也可以通过某些材料存储，称为相变材料。 相变材料在相变过程（例如熔化）期间以潜热的形式存储能量。 在熔化过程中，材料的温度不会改变，但它会吸收大量的能量，这些能量可以通过固化材料来回收。 一个主要问题是相变材料通常具有非常低的导热率，因此需要很长时间来存储和稍后回收热能。 通过这项研究计划，相变材料的热导率将通过嵌入具有非常高的内表面积的高导热多孔固体进行热对流来增强。 将进行数值模拟，以确定最佳的孔隙形状和尺寸，以最大限度地提高传热。 纳米流体（即悬浮在相变材料中的高导电性纳米颗粒）的使用也被认为可以提高导热性，并将在这项工作中进行数值研究。 除了储存热能外，还将研究热辐射的捕获。 将量化和优化使用多孔材料（以提高导热性和对流面积）和纳米流体（以提高光吸收性能）获得的增强效果。 这项研究计划的结果将是一个重要的计算工具库，将作为一个优秀的设计和优化平台，用于开发增强型太阳能热收集和存储设备，以及其他能源应用设备。 这些软件工具将作为开源软件向公众发布，目的是创建一个多机构协作平台。

The global demand for energy continues to increase rapidly, despite the fact that greenhouse gas emissions from energy production pose an increasingly urgent threat to the environment. While the renewable energy sector has grown significantly in recent years, and now makes up 14% of the total energy supply, this growth must be sustained in order to meet new targets for greenhouse gas emissions. Most of the current renewable energy mix is made up of hydroelectric, biofuels, and waste, while geothermal, solar, wind, and heat energies still account for less than 2% of the total energy supply. The relative absence of solar energy is particularly intriguing, given that the sun delivers many times more energy to the earth than what is needed to satisfy society's energy needs. The proposed research program focusses on the development of computational tools that will enable design and optimization of better devices for capturing and storing solar thermal (heat) energy. The fact that solar thermal energy is only available during daylight hours is a key factor that may limit its widespread use. Similar to using batteries to store electrical energy, thermal energy can also be stored by certain materials, known as phase change materials. Phase change materials store energy in the form of latent heat during a phase change process, such as melting. During a melting process, the temperature of a material does not change but it absorbs a large amount of energy, which can later be recovered by solidifying the material. One major issue is that phase change materials typically have very low thermal conductivity and therefore require a long time to store and later recover heat energy. Through this research program, the thermal conductivity of phase change materials will be enhanced by embedding a highly conductive porous solid with very high internal surface area for heat convection. Numerical simulations will be conducted to determine the optimal pore shapes and sizes to maximize the heat transfer enhancement. The use of nanofluids (i.e. high-conductivity nanoparticles suspended into the phase change material) is also known to enhance thermal conductivity and will be investigated numerically in this work. In addition to storage of thermal energy, the capture of thermal radiation will be studied. Enhancements obtained using porous materials (to enhance thermal conductivity and convection area) and nanofluids (to improve optical absorbance properties) will be quantified and optimized. The result of this research program will be a significant library of computational tools that will serve as an excellent design and optimization platform for the development of enhanced solar thermal collection and storage devices, as well devices for other energy applications. The software tools will be released to the public as open source, with the goal of creating a multi-institutional platform for collaboration.