Simulation of thermo-mechanical performance of pile geothermal heat exchanger (PGHE) considering temperature-depend interface behavior

Deqi Wang, Lin Lu, Ping Cui

Research output: Journal article publicationJournal articleAcademic researchpeer-review

11 Citations (Scopus)

Abstract

Pile geothermal heat exchanger (PGHE) has attracted great interests in recent years, but some new challenges have emerged with its application, especially in understanding its thermo-mechanical behaviors. In this paper, based on the experimental data from a modified direct shear test, a finite element simulation model is developed to investigate the thermo-mechanical behavior of PGHE. The simulation model has been verified by an in-suit test. The influence of interface behavior, thermal loads, and soil properties on the PGHE's thermo-mechanical behavior has been investigated. The results show that the changes in contact force and friction coefficient has to be considered in a comprehensive way in estimating the influence of thermal load on the bearing capacity of PGHE. Compared with the results without thermal loads, bearing capacity of PGHE shows a decreasing ratio of 8.7%, and an increasing ratio of heating is found to be 13.2%. In addition, the simulation results suggest that without head load imposed, at a certain depth, the axial stress has a linear relationship with the change of temperature, but when a head load is imposed, the linear relationship is only separately valid in each temperature region (heating or cooling). The thermo-mechanical performance of PGHE should be fully considered during the design stage, and this paper has the certain actual reference significance to engineering applications.

Original languageEnglish
Pages (from-to)356-366
Number of pages11
JournalApplied Thermal Engineering
Volume139
DOIs
Publication statusPublished - 5 Jul 2018

Keywords

  • Energy pile
  • Ground-coupled heat pump
  • Pile geothermal heat exchanger
  • Thermo-mechanical performance

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Industrial and Manufacturing Engineering

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