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School of Civil and Environmental Engineering
Ph.D. Thesis Defense Announcement
Engineered Transition Zone Systems for Advanced Heat Transfer in Thermo-Active Foundations
By
Fikret Atalay
Advisors:
Dr. J. David Frost
Committee Members:
Dr. Paul W. Mayne (CEE), Dr. Susan E. Burns (CEE), Dr. Sheng Dai (CEE), Dr. Marilyn A. Brown (PUBP)
Date & Time: Tuesday, March 12, 3:00pm
Location: SEB 122
Thermo-active foundations are a variation of the traditional geotechnical foundation system, where the foundation is fitted with fluid-circulating tubes and the constant temperature characteristics of the ground, which typically remains at an approximately constant temperature below the upper few meters, are utilized to use the foundation to exchange heat energy with the ground in addition to providing vertical and/or lateral foundation support. Most research to date on thermo-active foundations has focused on the hydro-mechanical response of the pile when subjected to a thermal gradient, while the thermal performance of these systems has received comparatively little attention. A novel concept termed the engineered transition zone (ETZ) has been developed with the potential to significantly enhance the thermal performance of shallow thermo-active foundations such as energy piles. An ETZ provides a means to introduce a thermally optimized zone between the foundation and the surrounding geomaterials to reduce thermal resistance. It also allows decoupling of the structural portion of the foundation from the thermal portion, such that the length of each component can be selected individually to meet the specific structural and thermal needs. Additionally, it allows for various circulation pipe configurations to be used (for example, helical loops) to further enhance heat transfer due to increased pipe surface area available for heat transfer. The performance of enhanced thermo-active foundations utilizing an ETZ have been studied both using a validated numerical model, as well as a physical, laboratory-scale model. In addition, laboratory and field tests have been performed for measurement of the thermal properties of soils typically encountered in the Piedmont physiographic region (in which Atlanta is located). Both the numerical and physical models show that there is a potential for significant improvement in thermal performance in the presence of an ETZ. Such improvements can make shallow thermo-active foundations a more feasible renewable and sustainable energy alternative for heating and cooling of buildings, particularly in areas where poor subsurface thermal properties might otherwise preclude their use.
