Thermal response tests using optical fiber thermometers

Hikari Fujii, Hiroaki Okubo, Ryuichi Itoi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

49 Citations (Scopus)


Thermal response tests (TRTs) were conducted using optical fiber thermometers in two types of ground heat exchangers (GHEs), coaxial type and U-tube type, drilled in a heterogeneous deposit in Fukuoka City, Japan. For the interpretation of the TRTs, the ground was sliced into sub-layers and the cylindrical source function was applied to each sub-layer to calculate the heat exchange performance between the ground and the GHEs. A nonlinear regression method was used to estimate the vertical distribution of thermal conductivities of the ground by minimizing the sum of squared errors between measured and calculated temperatures of ground and heat medium. The estimated thermal conductivity distribution showed good agreements with the rock type distributions and the groundwater flow information at the well site, indicating the reliability of the testing and interpretation method.

Original languageEnglish
Title of host publicationGeothermal Resources Council Transactions - GRC 2006 Annual Meeting: Geothermal Resources-Securing Our Energy Future
Number of pages7
Volume30 I
Publication statusPublished - 2006
EventGRC 2006 Annual Meeting: Geothermal Resources-Securing Our Energy Future - San Diego, CA, United States
Duration: Sept 10 2006Sept 13 2006


OtherGRC 2006 Annual Meeting: Geothermal Resources-Securing Our Energy Future
Country/TerritoryUnited States
CitySan Diego, CA

All Science Journal Classification (ASJC) codes

  • Geology
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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