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

尽管能源生产产生的温室气体排放对环境构成日益紧迫的威胁，但全球对能源的需求继续快速增长。虽然可再生能源部门近年来显著增长，目前占总能源供应的14%，但这种增长必须持续下去，才能实现温室气体排放的新目标。目前的可再生能源组合大部分由水力发电、生物燃料和废物组成，而地热、太阳能、风能和热能在总能源供应中所占比例仍不到2%。太阳能的相对匮乏尤其耐人寻味，因为太阳向地球提供的能量是满足社会能源需求所需能量的数倍。拟议的研究计划专注于开发计算工具，使设计和优化更好的设备来捕获和存储太阳能热(热)能成为可能。太阳能热能只在白天可用，这一事实可能会限制其广泛使用。与使用电池存储电能类似，热能也可以通过某些材料来存储，这种材料被称为相变材料。相变材料在相变过程中以潜热的形式储存能量，例如熔化。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，这些能量稍后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系数，因此需要很长时间来存储和稍后回收热能。通过这一研究计划，通过嵌入具有很高内表面积用于对流换热的高导电性多孔固体来提高相变材料的导热系数。将进行数值模拟，以确定最优的孔形状和大小，以最大限度地增强传热。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热导率，并将在本工作中进行数值研究。除了存储热能外，还将研究热辐射的捕获。利用多孔材料(提高导热系数和对流面积)和纳米流体(改善光吸收性能)获得的增强将被量化和优化。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集热和存储设备，以及用于其他能源应用的设备。这些软件工具将以开源形式向公众发布，目标是创建一个多机构合作平台。

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.