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Title: Advanced Testing Method for Ground Thermal Conductivity

Abstract

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.

Authors:
 [1];  [2];  [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)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Building Technologies Research and Integration Center (BTRIC)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1354667
Report Number(s):
ORNL/TM-2017/208
ED2701000; CEED509; CRADA/NFE-16-06144
DOE Contract Number:
AC05-00OR22725
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION

Citation Formats

Liu, Xiaobing, Clemenzi, Rick, and Liu, Su. Advanced Testing Method for Ground Thermal Conductivity. United States: N. p., 2017. Web. doi:10.2172/1354667.
Liu, Xiaobing, Clemenzi, Rick, & Liu, Su. Advanced Testing Method for Ground Thermal Conductivity. United States. doi:10.2172/1354667.
Liu, Xiaobing, Clemenzi, Rick, and Liu, Su. Sat . "Advanced Testing Method for Ground Thermal Conductivity". United States. doi:10.2172/1354667. https://www.osti.gov/servlets/purl/1354667.
@article{osti_1354667,
title = {Advanced Testing Method for Ground Thermal Conductivity},
author = {Liu, Xiaobing and Clemenzi, Rick and Liu, Su},
abstractNote = {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.},
doi = {10.2172/1354667},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}
}

Technical Report:

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