Energy and geotechnical behaviour of energy piles for different design solutions

Batini, Niccolò; Loria, Alessandro F. Rotta; Conti, Paolo; Testi, Daniele; Grassi, Walter

doi:10.1016/j.applthermaleng.2015.04.050

Cited by 162 publications

(58 citation statements)

References 62 publications

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“…However, this has mainly concerned energy piles, for example see Cecinato & Loveridge (2015); Loveridge & Cecinato (2016); Batini et al (2015). Parametric analyses performed to investigate the relative influence of different parameters on the heat exchange potential of energy geostructures have also been carried out by the authors.…”

Section: Introductionmentioning

confidence: 99%

Energy performance of diaphragm walls used as heat exchangers

Donna

Cecinato

Loveridge

et al. 2017

Proceedings of the Institution of Civil Engineers - Geotechnica

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The possibility of equipping diaphragm walls as ground heat exchangers to meet the full or partial heating and cooling demands of overlying or adjacent buildings has been explored in recent years. In this paper, the factors affecting the energy performance of diaphragm walls equipped as heat exchangers are investigated through finite element modelling. The numerical approach employed is first validated using available experimental data and then applied to perform parametric analyses. Parameters considered in the analysis include panel width, the ratio between the wall and excavation depths, heat transfer pipe spacing, concrete cover, heat-carrier fluid velocity, concrete thermal properties and the temperature difference between the air within the excavation and the soil behind the wall. The results indicate that increasing the number of pipes by reducing their spacing is the primary route to increasing energy efficiency in the short term. However, the thermal properties of the wall concrete and the temperature excess within the excavation space are also important, with the latter becoming the most significant in the medium to long term. This confirms the benefits of exploiting the retaining walls installed for railway tunnels and metro stations where additional sources of heat are available.

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Section: Introductionmentioning

confidence: 99%

Energy performance of diaphragm walls used as heat exchangers

Donna

Cecinato

Loveridge

et al. 2017

Proceedings of the Institution of Civil Engineers - Geotechnica

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“…Detailed information about the mathematical formulation that was used for the numerical analyses is presented by Batini et al (2015).…”

Section: Numerical Modellingmentioning

confidence: 99%

“…Over the last decade, an increasing amount of research has investigated the impact of thermal loads on the thermomechanical behaviour of isolated energy piles, including a series of full-scale in situ tests (Laloui et al, 2003;BourneWebb et al, 2009;Akrouch et al, 2014;Wang et al, 2014;Sutman et al, 2015;You et al, 2016), centrifuge (Ng et al, 2014;Stewart & McCartney, 2014;Goode & McCartney, 2015;Ng et al, 2015) and model-scale (Kalantidou et al, 2012;Kramer & Basu, 2014;Yavari et al, 2014) experiments, and numerical analyses (Laloui et al, 2006;Suryatriyastuti et al, 2012;Mimouni & Laloui, 2014;Olgun et al, 2014;Batini et al, 2015;Rotta Loria et al, 2015;Saggu & Chakraborty, 2015). Several in situ tests (McCartney & Murphy, 2012;Murphy et al, 2014;Mimouni & Laloui, 2015) and numerical analyses (Di Donna & Laloui, 2014;Jeong et al, 2014;Salciarini et al, 2015;Di Donna et al, 2016;Suryatriyastuti et al, 2016) have recently investigated this problem for energy pile groups.…”

Section: Introductionmentioning

confidence: 99%

Thermally induced group effects among energy piles

Loria

2017

Géotechnique

144

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The behaviour of conventional pile groups (e.g. closely spaced) that are subjected to mechanical loads has been shown to be different from the behaviour of single isolated piles. The so-called 'group effects' are responsible for this behaviour and must be considered for an optimal design of pile foundations. In recent years, energy piles have shown potential to work as both structural supports and geothermal heat exchangers, and thus are subjected to both mechanical and thermal loads. An increasing amount of research has investigated the previously unexplored impact of thermal loads on the thermo-mechanical behaviour of energy piles. However, no field data over typical timescales of practical geothermal applications have been available to analyse the development and impact of thermally induced group effects between energy piles (e.g. closely spaced) on their thermo-mechanical behaviour. To investigate this problem, a full-scale in situ test of a group of energy piles and coupled three-dimensional thermomechanical finite-element analyses were performed and are presented in this paper. This work demonstrates that significant thermally induced group effects characterise closely spaced energy piles. Attention must be devoted to these effects throughout the design process (e.g. geotechnical, structural and energy) of energy piles because they play an important role in the serviceability performance of these foundations.

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“…The advantage of the numerical approach, at least in theory, is the great variety of geometry, boundary conditions, length and time scales that could be analyzed. They are particularly appropriate to investigate the short-time behavior of shallow heat exchangers, often characterized by a relevant heat capacity (i.e., energy piles) [16]. However, result accuracy is always dependent on the accuracy of the input parameters (i.e., boundary conditions, geometry and thermo-physical properties) [17].…”

Section: Introductionmentioning

confidence: 99%

Dimensionless Maps for the Validity of Analytical Ground Heat Transfer Models for GSHP Applications

Conti

2016

Energies

Self Cite

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Abstract:This article provides plain and handy expressions to decide the most suitable analytical model for the thermal analysis of the ground source in vertical ground-coupled heat pump applications. We perform a comprehensive dimensionless analysis of the reciprocal deviation among the classical infinite, finite, linear and cylindrical heat source models in purely conductive media. Besides, we complete the framework of possible boreholes model with the "hollow" finite cylindrical heat source solution, still lacking in the literature. Analytical expressions are effective tools for both design and performance assessment: they are able to provide practical and general indications on the thermal behavior of the ground with an advantageous tradeoff between calculation efforts and solution accuracy. This notwithstanding, their applicability to any specific case is always subjected to the coherence of the model assumptions, also in terms of length and time scales, with the specific case of interest. We propose several dimensionless criteria to evaluate when one model is practically equivalent to another one and handy maps that can be used for both design and performance analysis. Finally, we found that the finite line source represents the most suitable model for borehole heat exchangers (BHEs), as it is applicable to a wide range of space and time scales, practically providing the same results of more complex models.

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Energy and geotechnical behaviour of energy piles for different design solutions

Cited by 162 publications

References 62 publications

Energy performance of diaphragm walls used as heat exchangers

Energy performance of diaphragm walls used as heat exchangers

Thermally induced group effects among energy piles

Dimensionless Maps for the Validity of Analytical Ground Heat Transfer Models for GSHP Applications

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