Planning Visit for Numerical and Experimental Investigation of Geothermal Heat Pumps

地热热泵和热桩是加热和冷却建筑物的节能手段。热桩埋设在现有的基础构件中，通常比周围的土壤更好地储存和传导热量。另一方面，地热热泵直接嵌入土壤中，可以独立于现有基础的约束进行设计，并且可以利用地下水流动来帮助保持更恒定的温度。这次对瑞士洛桑联邦理工学院（EPFL）的计划访问将探索在有关这些技术的两个重要研究问题上进行合作的机会。首先是反复加热和冷却循环对土壤性质的影响。根据给定土壤的类型和状态，这些循环可能会加强或削弱土壤，并可能导致土壤膨胀或收缩，影响使用这些系统的建筑物的基础和下层结构。第二个问题是这些能源土工结构的相对效率和成本效益。此次访问的一个计划结果是美国和瑞士双方就合作研究这些问题的数值和实验方案提出竞争性建议。利用瑞士洛桑联邦理工学院（EPFL）现有的热桩和伊利诺伊大学芝加哥分校计划使用的热泵，我们将监测土壤性能和土壤特性随时间的变化。然后，我们将开发模型来捕捉观察到的行为。规划访问和后续研究的更广泛影响包括：更好地了解土壤的行为和变化的条件，改进这种行为的计算机模型，以及评估不同能源土工结构的效率和效果的工具。最终，这项研究将导致更经济和更节能的方式来加热和冷却建筑物。此外，该项目将支持一名初级教员，并为一名美国本科生提供第一次国际研究机会。

Geothermal heat pumps and heat piles are energy efficient means to heat and cool buildings. Heat piles are embedded in existing foundation elements, which generally store and conduct heat better than the surrounding soil. Geothermal heat pumps, on the other hand, are embedded directly in the soil, can be designed independently of the constraints existing foundation, and can take advantage of groundwater flow to help maintain a more constant temperature.This planning visit to the Swiss Federal Institute of Technology, Lausanne (EPFL) will explore opportunities to collaborate on two important research questions regarding these technologies. The first is the effect of the repeated heating and cooling cycles on soil properties. Depending on the type and state of a given soil, these cycles may strengthen or weaken the soil, and may cause expansion or contraction of the soil, affecting the foundation and substructures of the buildings that use these systems. The second question is the comparative efficiency and cost effectiveness of these energy geostructures.A planned outcome of the visit is competitive proposals on the US and Swiss sides for a collaborative numerical and experimental program to study these questions. Using an existing heat pile at the Swiss Federal Institute of Technology, Lausanne (EPFL), and heat pumps planned at University of Illinois at Chicago, we will monitor the performance and changes in soil properties over time. We will then develop models to capture the observed behavior. The broader impacts of the planning visit and follow-up research include: better understanding of the behavior of soil and changing conditions, improved computer models for this behavior, and tools to evaluate the efficiency and effects of different energy geostructures. Ultimately, this research will lead to more economical and more energy efficient ways to heat and cool buildings. In addition, the project will support a junior faculty member and provide an American undergraduate student with a first international research opportunity.