Numerical simulation for thermal response test performance in closed-loop vertical ground heat exchanger

Jong Min Choi, Chulho Lee, Moonseo Park, Shin Hyung Kang, Hangseok Choi

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

In this study, a series of numerical analyses was performed in order to evaluate the performance of full-scale closed-loop vertical ground heat exchangers constructed in Wonju, South Korea. The circulating HDPE pipe, borehole and surrounding ground formation were modeled using FLUENT, a finite-volume method (FVM) program, for analyzing the heat transfer process of the ground heat exchanger system. Two user-defined functions (UDFs) accounting for the difference in the temperature of the circulating inflow and outflow fluid and the variation of ground temperature with depth were adopted in the FLUENT modeling. The thermal conductivities of grouts (cement vs. bentonite) measured in laboratory were used as input values in the numerical analyses to compare the thermal efficiency of the cement and bentonite grouts used for installing the closed-loop vertical ground heat exchanger. A series of numerical analyses was carried out to simulate in-situ thermal response tests performed in the construction site. From the comparison between the in-situ thermal response test results and numerical simulations, the average thermal conductivity of the ground formation in the construction site is back-calculated as approximately 4 W/mK. This value can be used in evaluating the long-term performance of the closed-loop vertical ground heat exchanger.

Original languageEnglish
Pages (from-to)1668-1673
Number of pages6
JournalScience China Technological Sciences
Volume54
Issue number7
DOIs
Publication statusPublished - 2011 Jul 1

Keywords

  • bentonite grout
  • cement grout
  • closed-loop vertical ground heat exchanger
  • finite-volume method
  • in-situ thermal response test
  • thermal conductivity

ASJC Scopus subject areas

  • Engineering(all)
  • Materials Science(all)

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