Research PaperThe importance of boundary conditions on the modelling of energy retaining walls
Section snippets
Shallow geothermal energy systems and energy retaining walls
Managing energy resources, reducing energy consumption and moving towards cleaner sources of energy are amongst the key challenges of the 21st century. Shallow geothermal technologies can help our progress towards these goals by providing clean renewable thermal energy for heating and cooling. Shallow geothermal or ground source heat pump (GSHP) systems consist of two circuits, connected via a GSHP, one transferring heat from and to the ground (primary circuit) and the other one transferring
Methodology
Finite element modelling is utilised to simulate the operation of geothermal systems within a typical underground structure in Melbourne, Australia, to investigate the heat transfer process between the ground, the energy wall and the air inside the underground structure. Typical geometry and conditions for a high-rise building incorporating energy soldier pile walls as part of a basement is adopted as a case study, noting that the analyses undertaken are of a generic nature and are applicable
System performance results for the different boundary conditions
This section presents the results from the modelling following the methodology outlined in Section 2 and analyses how different factors affect the performance of the energy structures and the heat transfer process. Each of the three conditions outlined in Section 2.4 are considered for both thermal load distributions presented in Section 2.3. All simulations were computed over 25 years of operation, to ensure adequate time for a realistic assessment of the system’s performance. To gain a
Heat transfer through the wall surfaces
In order to have a deeper understanding of the reasoning behind the results discussed in Section 3, this section investigates the effect of the heat transfer to/from the inside of the underground building space. One approach to investigating this is to examine the temperatures of the air inside the underground space. These air temperatures are shown in Fig. 12, for all three cases of approach (c) which models the air. For the temperature of the air is computed at the midpoint of the
Conclusion and remarks on appropriate boundary conditions
This study has presented a detailed long-term numerical investigation on soldier pile energy retaining walls, focusing on the applicability of different boundary conditions at the wall/slab surfaces and the heat transfer through those surfaces. A validated methodology to numerically model soldier pile energy walls has been presented and utilised to show that this boundary condition selection is crucial to having a representative model and useful results. In making this selection, a number of
CRediT authorship contribution statement
Nikolas Makasis: Conceptualization, Methodology, Software, Formal analysis, Visualization, Writing - original draft. Guillermo A. Narsilio: Conceptualization, Writing - review & editing, Supervision, Funding acquisition. Asal Bidarmaghz: Conceptualization, Writing - review & editing. Ian W. Johnston: Conceptualization, Writing - review & editing. Yu Zhong: Investigation, Data curation, Validation.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
Funding from the Australian Research Council (ARC) FT140100227, The University of Melbourne, the Melbourne Metro Rail Authority and the Victorian Government is much appreciated.
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