Date of Award:
8-2026
Document Type:
Dissertation
Degree Name:
Doctor of Philosophy (PhD)
Department:
Mechanical and Aerospace Engineering
Committee Chair(s)
Hailei Wang
Committee
Hailei Wang
Committee
Barton L. Smith
Committee
Nicholas A. Roberts
Committee
Yanqing Su
Committee
David W. Britt
Abstract
Ice-based cooling storage systems can reduce electricity costs and grid strain by making ice during off-peak hours and using it for air conditioning during the day. One promising design works by chilling water below its freezing point as it flows through a heat exchanger, then allowing it to freeze in a separate storage tank. The challenge is that the chilled water can freeze prematurely inside the heat exchanger itself, blocking the flow and shutting the system down. Preventing this unwanted freezing requires understanding how and where ice begins to form on surfaces, a process called nucleation.
This dissertation investigates ice nucleation on engineering surfaces to improve the reliability of these cooling systems. The research begins by developing improved statistical methods for measuring how likely a surface is to trigger freezing at a given temperature. These methods extract more information from experiments than previous approaches, particularly when only a limited number of tests are available.
The central discovery of this work is that the specific locations on a surface where ice tends to form, known as active nucleation sites, are not fixed. Through hundreds of repeated freeze-thaw experiments captured with high-speed cameras, this research shows that these sites change over time: they gradually shift in behavior, respond to temperature history, and can be permanently altered by heating. This finding challenges the longstanding assumption that surface freezing properties are constant and has implications for how nucleation experiments are interpreted.
These dynamic behaviors were confirmed across multiple materials, including aluminum and Teflon, demonstrating that the phenomenon is general rather than specific to one surface. Finally, the measured nucleation properties were used to build a design tool that predicts freezing risk inside a heat exchanger based on the actual surface characteristics. This tool demonstrates how measured surface properties can inform more specific operating limits than the general rules of thumb currently used in practice.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Gardner, Daniel B., "Toward Risk-Informed Design of Supercooling Heat Exchangers: Statistical Inference and Experimental Investigation of Heterogeneous Ice Nucleation" (2026). All Graduate Theses and Dissertations, Fall 2023 to Present. 826.
https://digitalcommons.usu.edu/etd2023/826
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