Engineered Thermal Transition Zones for Enhanced Geotechnical Foundation Systems

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Working with an industry partner, this research will develop a new design configuration and installation methodology for heat exchange thermal piles which deviates from the current approach of internally modifying conventional structural piles. This will be achieved by replacing the conventional system with a transition zone that is manufactured in-place between a conventional structural pile and the surrounding soil to significantly increase thermal performance of the pile system. Proof-of-concept modeling has shown the potential for dramatic increases in the thermal performance of an energy pile that can make them a more feasible renewable and sustainable energy alternative for heating and cooling buildings, including single and multi-family residential buildings. The study will use the new insight from the proof-of-concept modeling as the motivation for laboratory and field scale physical and numerical testing. The broader impacts of being able to dramatically alter the performance and efficiency of thermal pile systems has significant implications on global heating and cooling needs in both developed and developing countries, and can contribute to reducing greenhouse gas emissions. This research is very much aligned with the concept and philosophy of sustainable infrastructure, and encourages a systematic approach to evaluating alternative approaches across the key dimensions most likely to influence system performance including environmental, societal and economic impact, as well as technical factors. Projects based on this research will be developed for the Georgia Tech class "Sustainable Subsurface Infrastructure."In order to better understand the various factors influencing thermal performance of energy piles and to optimize heat transfer characteristics, a series of tasks will build on the insights derived during the proof-of-concept studies. The focus of this investigation is to not only to study the problem in a controlled lab environment, but also to develop practical methodologies for utilization of the results in designing and installing thermally optimized energy piles. To achieve this, the project will first design, fabricate and utilize a laboratory scale apparatus to test model engineered transition zone piles with different soil conditions and different boundary conditions. The tests will be used to validate additional numerical simulations that extend the findings of the original proof-of-concept numerical model studies to design prototype full scale field systems. Working with an industry partner, a full-scale field system will be installed and monitored during a series of trials to assess both the initial response as well as the longer term performance of the system as heating and cooling cycles are applied to the system. The installation method to be used in the field involves the strategic repurposing of existing equipment to allow a staged installation procedure of the new thermal pile configuration. This has important implications for the adoption of the method in practice. Upon completion of the full scale field testing, a design methodology that can be used for future installations in a variety of subsurface conditions with engineered thermal transition zones of different dimensions will be developed.