Experimental and numerical investigations of the behaviour of a heat exchanger pile

Laloui, Lyesse; Nuth, Mathieu; Vulliet, L.

doi:10.1002/nag.499

Cited by 573 publications

(266 citation statements)

References 5 publications

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“…Codes developed for use with borehole heat exchangers, eg [15,16] are equally applicable to pile applications. In addition, numerical methods may be used to couple the thermal and mechanical aspects of the pile behaviour [17]. This paper makes used of numerical solution of the diffusion equation to consider a wide range of pile heat exchanger geometries.…”

Section: Existing Design Approachesmentioning

confidence: 99%

Temperature response functions (G-functions) for single pile heat exchangers

Loveridge

Powrie

2013

Energy

106

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Foundation piles used as heat exchangers as part of a ground energy system have the potential to reduce energy use and carbon dioxide emissions from new buildings. However, current design approaches for pile heat exchangers are based on methods developed for boreholes which have a different geometry, with a much larger aspect (length to diameter) ratio. Current methods also neglect the transient behaviour of the pile concrete, instead assuming a steady state resistance for design purposes. As piles have a much larger volume of concrete than boreholes, this neglects the significant potential for heat storage within the pile. To overcome these shortcomings this paper presents new pile temperature response functions (G-functions) which are designed to reflect typical geometries of pile heat exchangers and include the transient response of the pile concrete. Owing to the larger number of pile sizes and pipe configurations which are possible with pile heat exchangers it is not feasible to developed a single unified G-function and instead upper and lower bound solutions are provided for different aspects ratios. (172 words)

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Section: Existing Design Approachesmentioning

confidence: 99%

Temperature response functions (G-functions) for single pile heat exchangers

Loveridge

Powrie

2013

Energy

106

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“…The extent to which this heating zone extends continues to grow up to t ¼ 120 min, at which point no further changes were detected. these observed changes in soil temperature along the length of an energy pile that have been postulated by Laloui et al (2006), Bourne-Webb et al (2009), andBrandl (2006) as the likely contributing factor for increased foundation movements in geothermal structures due to changes in side friction characteristics arising from thermal expansion and contraction of the soil.…”

Section: Energy Pile Applicationmentioning

confidence: 66%

Transparent Soil to Model Thermal Processes: An Energy Pile Example

Black

Tatari

2015

Geotech. Test. J.

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Managing energy resources is fast becoming a crucial issue of the 21st century, with groundbased heat exchange energy structures targeted as a viable means of reducing carbon emissions associated with regulating building temperatures. Limited information exists about the thermo-dynamic interactions of geothermal structures and soil owing to the practical constraints of placing measurement sensors in proximity to foundations; hence, questions remain about their long-term performance and interaction mechanics. An alternative experimental method using transparent soil and digital image analysis was proposed to visualize heat flow in soil. Advocating the loss of optical clarity as a beneficial attribute of transparent soil, this paper explored the hypothesis that temperature change will alter its refractive index and therefore progressively reduce its transparency, becoming more opaque. The development of the experimental methodology was discussed and a relationship between pixel intensity and soil temperature was defined and verified. This relationship was applied to an energy pile example to demonstrate heat flow in soil. The heating zone of influence was observed to extend to a radial distance of 1.5 pile diameters and was differentiated by a visual thermal gradient propagating from the pile. The successful implementation of this technique provided a new paradigm for transparent soil to potentially contribute to the understanding of thermo-dynamic processes in soil.

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“…Only three studies have been identified: one in Austria (Brandl, 1998), one in Switzerland (Laloui et al, 2006) and one in the UK (Bourne-Webb et al, 2009). The authors are aware of some other tests carried out in Australia and the US, but the results of these tests have not been published yet.…”

Section: Geostructural Behaviour Of Energy Pilesmentioning

confidence: 99%

“…The three published cases, while providing useful insights into the behaviour of these systems, have shortcomings, such as presenting incomplete information and not being representative of an operational system or being of short duration (Bourne-Webb et al, 2012). The results of these in situ experiences show that application of a thermal load induces a significant change in the structural behaviour of a foundation pile (Amis et al, 2008;Bourne-Webb et al, 2009;Laloui et al, 2006). In general, the previous studies showed that heating of a pile induces an additional compression stress in the pile and increases the mobilised shear stress.…”

Section: Geostructural Behaviour Of Energy Pilesmentioning

confidence: 99%

Energy piles: current state of knowledge and design challenges

Abuel-Naga

Raouf²,

Raouf³

et al. 2015

Environmental Geotechnics

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Energy piles offer a promising and eco-friendly technique to heat or cool buildings. Energy piles can be exploited as ground heat exchangers of a ground source heat pump system. In such application, the energy pile and its surrounding soil are subjected to temperature changes that could significantly affect the pile-soil interaction behaviour. The aim of this paper is to review the current state of knowledge on the design of energy piles in terms of the geostructural and heat exchanger functions. Furthermore, a conceptual understanding of the potential temperature effects on the mechanical behaviour of piles is proposed in this paper. Based on this conceptual understanding as well as the reported thermo-hydro-mechanical behaviour of saturated clays in the literature, the challenging geotechnical aspects facing the energy pile design are highlighted, and further research efforts to refine them are recommended. Ayman M.I. Raouf BE (Hons)

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Experimental and numerical investigations of the behaviour of a heat exchanger pile

Cited by 573 publications

References 5 publications

Temperature response functions (G-functions) for single pile heat exchangers

Temperature response functions (G-functions) for single pile heat exchangers

Transparent Soil to Model Thermal Processes: An Energy Pile Example

Energy piles: current state of knowledge and design challenges

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