Comparison of effective thermal conductivity in closed-loop vertical ground heat exchangers

Chulho Lee, Moonseo Park, Sunhong Min, Shin Hyung Kang, Byonghu Sohn, Hangseok Choi

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

Performing a series of in-situ thermal response tests, the effective thermal conductivity of six vertical closed-loop ground heat exchangers was experimentally evaluated and compared to each other, which were constructed in a test bed in Wonju, South Korea. To compare thermal efficiency of the ground heat exchangers in field, the six boreholes were constructed with different construction conditions: i.e., different grouting materials (cement vs. bentonite), different shape of heat exchange pipe-sections (conventional U-loop type vs. new 3 pipe-type), and different additives (silica sand vs. graphite). One observation borehole was installed in the middle of the test site to measure a subsurface temperature change during performing the in-situ thermal response test. From the test results, it can be shown that cement grouting has a higher effective thermal conductivity than that of bentonite grouting, and graphite better performs over silica sand as a thermally enhancing addictive. In addition, a new 3 pipe-type heat exchanger yields less thermal interference between the inlet and outlet pipe than the conventional U-loop type heat exchanger, which results in superior thermal performance.

Original languageEnglish
Pages (from-to)3669-3676
Number of pages8
JournalApplied Thermal Engineering
Volume31
Issue number17-18
DOIs
Publication statusPublished - 2011 Dec 1

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Heat exchangers
Thermal conductivity
Grouting
Pipe
Silica sand
Bentonite
Boreholes
Cements
Graphite
Hot Temperature
Temperature

Keywords

  • Ground heat exchanger
  • In-situ thermal response test
  • Thermal conductivity
  • Thermal interference

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Industrial and Manufacturing Engineering

Cite this

Comparison of effective thermal conductivity in closed-loop vertical ground heat exchangers. / Lee, Chulho; Park, Moonseo; Min, Sunhong; Kang, Shin Hyung; Sohn, Byonghu; Choi, Hangseok.

In: Applied Thermal Engineering, Vol. 31, No. 17-18, 01.12.2011, p. 3669-3676.

Research output: Contribution to journalArticle

Lee, Chulho ; Park, Moonseo ; Min, Sunhong ; Kang, Shin Hyung ; Sohn, Byonghu ; Choi, Hangseok. / Comparison of effective thermal conductivity in closed-loop vertical ground heat exchangers. In: Applied Thermal Engineering. 2011 ; Vol. 31, No. 17-18. pp. 3669-3676.
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