Advanced Testing Method for Ground Thermal Conductivity

Technical Report · Sat Apr 01 04:00:00 EDT 2017

DOI:https://doi.org/10.2172/1354667· OSTI ID:1354667

Liu, Xiaobing ^[1]; Clemenzi, Rick ^[2]; Liu, Su ^[3]

---

1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Geothermal Design Center Inc., Asheville, NC (United States)
3. Univ. of Tennessee, Knoxville, TN (United States)

A new method is developed that can quickly and more accurately determine the effective ground thermal conductivity (GTC) based on thermal response test (TRT) results. Ground thermal conductivity is an important parameter for sizing ground heat exchangers (GHEXs) used by geothermal heat pump systems. The conventional GTC test method usually requires a TRT for 48 hours with a very stable electric power supply throughout the entire test. In contrast, the new method reduces the required test time by 40%–60% or more, and it can determine GTC even with an unstable or intermittent power supply. Consequently, it can significantly reduce the cost of GTC testing and increase its use, which will enable optimal design of geothermal heat pump systems. Further, this new method provides more information about the thermal properties of the GHEX and the ground than previous techniques. It can verify the installation quality of GHEXs and has the potential, if developed, to characterize the heterogeneous thermal properties of the ground formation surrounding the GHEXs.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Building Technologies Research and Integration Center (BTRIC)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1354667
• Report Number(s): ORNL/TM-2017/208; ED2701000; CEED509; CRADA/NFE-16-06144
• Country of Publication: United States
• Language: English

Related Subjects

47 OTHER INSTRUMENTATION