Heat Transfer Enhancement of Graphite–modified Concrete Energy Piles

  • Haoran Guo University of Science and Technology Beijing
  • Lan Qiao University of Science and Technology Beijing
  • Yunyang Xiao University of Science and Technology Beijing
  • Xiangyu Ren University of Wollongong

Abstract

Designed for utilizing the ground-source systems for heating and cooling, the use of energy piles in commercial and residentialbuildings has increased exponentially especially in Europe. The heat transfer efficiency of energy piles may directly influencethe energy-saving effect on buildings. Apart from the optimization of pipe laying, many other factors can also influence theheat transfer efficiency of energy piles. In this study, a new method that can increase the heat transfer efficiency of energypiles was proposed to explore the influences of adding graphite powder with high thermal conductivity to pile concrete on theheat transfer efficiency of energy piles. The thermal resistance models of energy piles in three different pipe-burying modeswere constructed by combining the 2D plane method and the heat transfer mechanism of energy piles. The internal heattransfer characteristics of energy piles at different temperatures, graphite contents, and pipe-burying modes were discussedby combining the indoor thermal conductivity test of graphite-modified concrete. The external heat transfer characteristicsof graphite-modified concrete energy piles were analyzed through numerical simulation analysis. Results demonstrate thatthe increase in graphite contents is beneficial to heat transfer in energy piles. In particular, thermal conductivity significantlyincreases when the graphite content exceeds 5%. The high temperature in the pipe is also conducive to the thermal conductivityof the energy pile. The thermal conductivity of the concrete samples with 8% graphite content in an environment at 40°Cis 1.35 times that at 20°C. The heat transfer efficiency of the spiral coil-type energy pile is higher than those of single-U anddouble-U tube energy piles. The proposed method provides a certain reference for improving the heat transfer efficiency ofenergy piles and constructing the internal and external heat transfer models in energy piles.

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Published
2018-12-28
How to Cite
GUO, Haoran et al. Heat Transfer Enhancement of Graphite–modified Concrete Energy Piles. Journal of Power Technologies, [S.l.], v. 98, n. 4, p. 345–351, dec. 2018. ISSN 2083-4195. Available at: <https://papers.itc.pw.edu.pl/index.php/JPT/article/view/1422>. Date accessed: 14 july 2024.
Section
Energy Engineering and Technology

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