Between Dec 19, 2024 and Jan 2, 2025, datasets can be submitted to DRUM but will not be processed until after the break. Staff will not be available to answer email during this period, and will not be able to provide DOIs until after Jan 2. If you are in need of a DOI during this period, consider Dryad or OpenICPSR. Submission responses to the UDC may also be delayed during this time.
 

Modeling and performance enhancement of thermo-active foundations for cold climates - Case of Minnesota

Loading...
Thumbnail Image

Persistent link to this item

Statistics
View Statistics

Journal Title

Journal ISSN

Volume Title

Title

Modeling and performance enhancement of thermo-active foundations for cold climates - Case of Minnesota

Published Date

2023-07

Publisher

Type

Thesis or Dissertation

Abstract

In the United States, building energy consumption accounts for approximately 40%, witha significant portion used to meet heating and cooling needs. The reliance on fossil fuels to meet space heating and hot water needs leads to substantial CO2 emissions. Therefore, there is an urgent need for clean and sustainable energy technologies to decarbonize building energy usage. Among these technologies, ground source heat pump (GSHP) systems have gained significant attention due to their high efficiency and consistent performance across different seasons. However, their widespread adoption is hindered by the high initial costs, despite their lower operation and maintenance expenses. One promising approach to mitigate this issue is coupling the GSHP system’s ground heat exchanger with the building foundation, known as the “thermo-active foundation (TAF).” By doing so, the capital cost and space requirements of the entire system can be reduced. Additionally, integrating the ground heat exchanger with the building foundation serves dual purposes of structural support and heat exchange with the ground. This study focuses on evaluating and enhancing the performance of a vertical U-loopground heat exchanger integrated into a 20-meter deep helical steel pile. A thoroughly validated and verified transient computational fluid dynamics numerical model is employed for this purpose. The model is utilized to investigate the short-term (one year) and long-term (five years) transient performance of the system in the cold climate of Minnesota, where there is a significant disparity between heating and cooling loads. A building energy model, representing a typical small residential house in Minnesota with an area of 2026 square feet, is developed using BEopt software to determine the annual heating and cooling loads. Three normalized building load cases (0.25, 0.33, and 0.4 tons) are then used to determine the capacity per pile. For the larger 0.4 tons load, detailed parametric studies are conducted to establish performance under different inlet fluid velocities (considering laminar and turbulent flow regimes), and the TAF’s location in relation to the building. The results demonstrate that the COP (coefficient of performance) remains constant at around 3.3 for all pile locations, indicating that the system’s performance is independent of the pile’s location. Moreover, for all flow velocities, the COP remains the same, around 3.3, with laminar flow being preferable due to lower pump power requirements. To enhance performance, thermal energy storage using phase change material (PCM), isincorporated inside the TAF. Two PCM tubes, each with a volume of 0.0053093 m3 (5.30 kg), are inserted beside both sides of the pile in the ground. The performance enhancement for different building loads (0.4 tons, 0.33 tons, and 0.25 tons) is compared to determine the optimal amount of heating load per pile necessary to meet the total building load over a year in Duluth, MN using PCM. The results indicate that a 0.4 tons load per pile is the most economical option, requiring eight piles to meet the house’s load in Duluth, MN, with an additional heating requirement during 6.30% of the year. The system’s performance is also assessed in other locations in Minnesota, including International Falls and Saint Paul, to compare long-term performance with Duluth for a 0.4 tons building load. The average annual COP using PCM in Duluth, International Falls, and Saint Paul is found to be 4.09, 4.20, and 4.60, respectively, with Saint Paul exhibiting the best performance due to its higher cooling energy demand and low peak heating loads. However, despite having a higher COP than Duluth, International Falls shows the worst performance owing to the high heating loads, thus requiring more auxiliary heating.

Keywords

Description

University of Minnesota M.S.M.E. thesis. July 2023. Major: Mechanical Engineering. Advisor: Alison Hoxie. 1 computer file (PDF); xii, 78 pages.

Related to

Replaces

License

Series/Report Number

Funding information

Isbn identifier

Doi identifier

Previously Published Citation

Other identifiers

Suggested citation

Agarwala, Prem. (2023). Modeling and performance enhancement of thermo-active foundations for cold climates - Case of Minnesota. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/258572.

Content distributed via the University Digital Conservancy may be subject to additional license and use restrictions applied by the depositor. By using these files, users agree to the Terms of Use. Materials in the UDC may contain content that is disturbing and/or harmful. For more information, please see our statement on harmful content in digital repositories.