Response of unsaturated soils to heating of geothermal energy pile

Sani, Abubakar Kawuwa; Singh, Rao Martand

doi:10.1016/j.renene.2018.11.032

Cited by 56 publications

(12 citation statements)

References 24 publications

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“…To minimize the influence of assumed boundary conditions on the numerical results, the calculation area of the ground is considered to be enlarged as much as possible. From previous studies, Sani and Singh [ 23 ] and Péron et al [ 36 ] pointed out that the influencing radii of temperature in sandy soil, silt soil, and clay are 6 m, 5 m, and 4 m, respectively. Moreover, Ma and Wang [ 37 ] found that when the clearance distance between the lower boundary of the ground and the bottom of the energy pile is more than 10 m in the numerical simulation, the influence of the bottom boundary on the temperature change of the ground can be ignored to a certain extent.…”

Section: Numerical Simulation and Analysismentioning

confidence: 99%

“…You et al [ 22 ] carried out a series of field thermal response and thermal performance experiments to study the heat transfer ability of cement-fly ash-gravel (CFG) piles at various conditions and their results can be used as benchmark for the design of CFG piles in later relevant engineering. In terms of numerical studies of energy piles, Sani and Singh [ 23 ] employed a numerical model to investigate the thermal response of an energy pile in unsaturated soil and found that some factors (e.g., soil saturation condition, the heating operational time, and heat injection rate) can affect the ground temperature variation around the energy pile and the performance of the whole system. Batini et al [ 24 ] evaluated the effects of different parameters such as the geometric configuration of the heat exchanger, the foundation aspect ratio, the fluid flow rate, and the fluid mixture composition on the energy and geotechnical properties of energy piles and found that the geometric configuration of heat exchanger strongly affected their performance.…”

Section: Introductionmentioning

confidence: 99%

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Field Test and Numerical Simulation on the Long-Term Thermal Response of PHC Energy Pile in Layered Foundation

Zhang

Cao

Liu

et al. 2021

Sensors

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Investigation on the long-term thermal response of precast high-strength concrete (PHC) energy pile is relatively rare. This paper combines field experiments and numerical simulations to investigate the long-term thermal properties of a PHC energy pile in a layered foundation. The major findings obtained from the experimental and numerical studies are as follows: First, the thermophysical ground properties gradually produce an influence on the long-term temperature variation. For the soil layers with relatively higher thermal conductivity, the ground temperature near to the energy pile presents a slowly increasing trend, and the ground temperature response at a longer distance from the center of the PHC pile appears to be delayed. Second, the short- and long-term thermal performance of the PHC energy pile can be enhanced by increasing the thermal conductivity of backfill soil. When the thermal conductivities of backfill soil in the PHC pile increase from 1 to 4 W/(m K), the heat exchange amounts of energy pile can be enhanced by approximately 30%, 79%, 105%, and 122% at 1 day and 20%, 47%, 59%, and 66% at 90 days compared with the backfill water used in the site. However, the influence of specific heat capacity of the backfill soil in the PHC pile on the short-term or long-term thermal response can be ignored. Furthermore, the variation of the initial ground temperature is also an important factor to affect the short-and-long-term heat transfer capacity and ground temperature variation. Finally, the thermal conductivity of the ground has a significant effect on the long-term thermal response compared with the short-term condition, and the heat exchange rates rise by about 5% and 9% at 1 day and 21% and 37% at 90 days as the thermal conductivities of the ground increase by 0.5 and 1 W/(m K), respectively.

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Section: Numerical Simulation and Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Field Test and Numerical Simulation on the Long-Term Thermal Response of PHC Energy Pile in Layered Foundation

Zhang

Cao

Liu

et al. 2021

Sensors

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“…The modelling approach was based on the scenario where piles exist in a grid of 7 by 7 group of piles (shown in Fig 1a), spaced at 7 m in both longitudinal and lateral directions. In total, 49 piles exists in the group with each having a diameter of 600 mm, and a length of 30 m. As regards to the transitioning from the 3D problem into 2D axisymmetric, the findings of [14,15] were adopted and used. They reported that heat predominantly disperses in the radial plane of a GEP.…”

Section: Numerical Model Development 31 Model Descriptionmentioning

confidence: 99%

Numerical investigation of the performance of group of geothermal energy piles in unsaturated sand

Sani

Singh

2020

E3S Web Conf.

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The use of foundation structures (piles) coupled to a heat pump system, commonly referred to as geothermal energy pile (GEP) system, provides a renewable energy solution of achieving space heating and cooling in buildings; whilst also being utilised for the structural stability of the overlying structures. The system operates by exchanging the low-grade heat energy within the shallow earth surface with the building, via the circulation of heat carrier fluid enclosed in a high-density polyethylene plastic pipes. In summer, heat energy is extracted from the building and transferred into the ground to achieve space cooling. While in winter, the ground heat energy is harnessed and transferred to the building to achieve sustainable space heating. This paper investigates the thermal performance of group of GEP system under the effects of different initial soil pore water content. Through the five-year simulation’s period, it was found that the increase in soil pore water content decreases the possibility of thermal interaction between the GEPs in the group. Also, it was observed that the trend in maximum temperature witnessed within the soil domain decreases nonlinearly during the five years period.

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“…The pile thermal load has in most cases been applied across the elements forming the pile, either as a stepped or ramped temperature change or a prescribed heat flux [2,3,7]. In some analyses, the thermal load has been applied along lines within the pile body (ring in 2D analysis), again either as temperature change [6,13,16,20] or a heat flux [15,19].…”

Section: Introductionmentioning

confidence: 99%

Effect of thermal boundary conditions on the response of thermally-activated floating piles in a cohesive material

et al. 2020

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The application of thermally-activated foundations has received significant attention in the last decade with a number of large- and small-scale tests having been undertaken. Alongside these physical studies, a number of investigations utilising numerical analysis have been undertaken. The majority of analyses are transient with durations from a few hours up to 10 years. A broad range of thermal boundary and initial conditions have been applied in these analyses, and only a limited number of studies have explicitly considered the surface boundary imposed by an overlying structure, let alone considered what effect variations in the operational temperatures of the structure might have on the foundations. The work presented in this paper had the objective of systematically examining these assumptions and the effect they have on the predicted response of a thermally-activated pile foundation, and if important, which is the most appropriate set of conditions to use.

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Response of unsaturated soils to heating of geothermal energy pile

Cited by 56 publications

References 24 publications

Field Test and Numerical Simulation on the Long-Term Thermal Response of PHC Energy Pile in Layered Foundation

Field Test and Numerical Simulation on the Long-Term Thermal Response of PHC Energy Pile in Layered Foundation

Numerical investigation of the performance of group of geothermal energy piles in unsaturated sand

Effect of thermal boundary conditions on the response of thermally-activated floating piles in a cohesive material

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