Date of Graduation
Statler College of Engineering and Mineral Resources
Mechanical and Aerospace Engineering
The utilization of geothermal ground heat sources has been demonstrated at both large and small scales across the world. However, methods of extraction of the hot working fluids are often a source of energy inefficiency and high capital expense. Current techniques to extract geothermal fluids rely on mechanically and electrically driven down-hole components that require maintenance on a regular basis. In providing a solution, one approach that reduces complexity, decreases maintenance, and allows access to fluids at greater depth is an airlift approach. The airlift approach relies on injection of gas at a depth within a geothermal well to lift the working fluid to the surface using a density difference pumping strategy.
This literature review focuses on existing methods and approaches to modeling the system throughout three scales: a microscale, intermediate scale, and macroscale. The microscale focuses on modeling considerations near the sparger head during bubble formation. The intermediate scale focuses on modeling techniques for characterizing bubble coalescing and gas hold-up. The macroscale focuses on modeling approaches over large length scales using a drift- flux model. Because of the varying phenomena experienced within the well, specifically complex bubble behavior and gas hold-up, it was a consensus amongst the literature to require a combination of in-depth experimental testing in combination with simulations to properly capture airlift flow rates.
This literature review provides a review of modeling approaches that could be used to design a geothermal airlift system. Overall, the airlift system has the potential future application for power generation, district heating, and residential heating/cooling in geographic regions previously not considered based on existing technologies. The computational tools are currently available but it will require in-depth study of geothermal fluids under two-phase flow regimes.
Ware, Lucas A., "Literature Review on Modeling of Density Difference Pumping Strategy for Geothermal Applications" (2020). Graduate Theses, Dissertations, and Problem Reports. 7983.