Influences on the thermal efficiency of energy piles
Influences on the thermal efficiency of energy piles
Energy piles have recently emerged as a viable alternative to borehole heat exchangers, but their energy efficiency has so far seen little research. In this work, a finite element numerical model is developed for the accurate 3D analysis of transient diffusive and convective heat exchange phenomena taking place in geothermal structures. The model is validated by reproducing both the outcome of a thermal response test carried out on a test pile, and the average response of the linear heat source analytical solution. Then, the model is employed to carry out a parametric analysis to identify the key factors in maximising the pile energy efficiency. It is shown that the most influential design parameter is the number of pipes, which can be more conveniently increased, within a reasonable range, compared to increasing the pile dimensions. The influence of changing pile length, concrete conductivity, pile diameter and concrete cover are also discussed in light of their energetic implications. Counter to engineering intuition, the fluid flow rate does not emerge as important in energy efficiency, provided it is sufficient to ensure turbulent flow. The model presented in this paper can be easily adapted to the detailed study of other types of geothermal structures.
energy piles, geothermal, thermal efficiency, thermal response test, numerical modelling, convection–diffusion
1021-1033
Cecinato, F.
39ce6c19-7429-465e-a769-d9b500a496e6
Loveridge, F.A.
fb5b7ad9-d1b8-40d3-894b-bccedf0e8a77
15 March 2015
Cecinato, F.
39ce6c19-7429-465e-a769-d9b500a496e6
Loveridge, F.A.
fb5b7ad9-d1b8-40d3-894b-bccedf0e8a77
Abstract
Energy piles have recently emerged as a viable alternative to borehole heat exchangers, but their energy efficiency has so far seen little research. In this work, a finite element numerical model is developed for the accurate 3D analysis of transient diffusive and convective heat exchange phenomena taking place in geothermal structures. The model is validated by reproducing both the outcome of a thermal response test carried out on a test pile, and the average response of the linear heat source analytical solution. Then, the model is employed to carry out a parametric analysis to identify the key factors in maximising the pile energy efficiency. It is shown that the most influential design parameter is the number of pipes, which can be more conveniently increased, within a reasonable range, compared to increasing the pile dimensions. The influence of changing pile length, concrete conductivity, pile diameter and concrete cover are also discussed in light of their energetic implications. Counter to engineering intuition, the fluid flow rate does not emerge as important in energy efficiency, provided it is sufficient to ensure turbulent flow. The model presented in this paper can be easily adapted to the detailed study of other types of geothermal structures.
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Cecinato & Loveridge Rotary Pile Efficiency.pdf
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Accepted/In Press date: 1 February 2015
Published date: 15 March 2015
Keywords:
energy piles, geothermal, thermal efficiency, thermal response test, numerical modelling, convection–diffusion
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Infrastructure Group
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Local EPrints ID: 374079
URI: http://eprints.soton.ac.uk/id/eprint/374079
ISSN: 0360-5442
PURE UUID: 65fa6f85-d35e-4782-8944-068e65a20e81
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Date deposited: 05 Feb 2015 11:46
Last modified: 14 Mar 2024 19:01
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Author:
F. Cecinato
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