Analysis and design methods for energy geostructures

Bourne–Webb, Peter J.; Burlon, Sébastien; Javed, Saqib; Kürten, Sylvia; Loveridge, Fleur

doi:10.1016/j.rser.2016.06.046

Cited by 84 publications

(46 citation statements)

References 70 publications

(107 reference statements)

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“…A library of such data can be developed for particular geometry and thermal property variations for repeated application in modelling exercises. Conducting a modelling exercise (i.e., making long-term predictions of fluid temperatures and heat transfer rates for given inlet temperatures and flow rates) is carried out in relatively simple coding that reads the weighting factors and implements the heat balance Equations (4) and (5), along with the boundary conditions Equations (14) and (15). This was implemented as a stand-alone application and also in the form of a component model in the TRNSYS simulation environment [39].…”

Section: Model Implementationmentioning

confidence: 99%

“…A numerical method to investigate thermal performance of DWHEs was presented by Kürten et al [14], and was validated against laboratory results. The authors of Bourne-Webb et al [15] compared the methods used for evaluating BHEs and energy geostructures, and outlined their commonalities and differences. In a different research, Bourne-Webb et al [16] carried out numerical studies to demonstrate the heat transfer procedure in DWHEs, and reported that the key process is the one between the the air-void and the wall rather than the ground.…”

Section: Introductionmentioning

confidence: 99%

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A Model of a Diaphragm Wall Ground Heat Exchanger

et al. 2020

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Ground thermal energy is a sustainable source that can substantially reduce our dependency on conventional fuels for heating and cooling of buildings. To exploit this source, foundation sub-structures with embedded heat exchanger pipes are employed. Diaphragm wall heat exchangers are one such form of ground heat exchangers, where part of the wall is exposed to the basement area of the building on one side, while the other side and the further depth of the wall face the surrounding ground. To assess the thermal performance of diaphragm wall heat exchangers, a model that takes the wall geometry and boundary conditions at the pipe, basement, and ground surfaces into account is required. This paper describes the development of such a model using a weighting factor approach, known as Dynamic Thermal Networks (DTN), that allows representation of the three-dimensional geometry, required boundary conditions, and heterogeneous material properties. The model is validated using data from an extended series of thermal response test measurements at two full-scale diaphragm wall heat exchanger installations in Barcelona, Spain. Validation studies are presented in terms of comparisons between the predicted and measured fluid temperatures and heat transfer rates. The model was found to predict the dynamics of thermal response over a range of operating conditions with good accuracy and using very modest computational resources.

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Section: Model Implementationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Model of a Diaphragm Wall Ground Heat Exchanger

et al. 2020

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“…Heat exchange processes occurring in boreholes are object of continuous studies from many different sides; a more refined design can reduce installation costs and improve heat transfer and heat pump efficiency (see for instance the reviews [10,11] and references quoted therein). Specifically, the physical processes involved can be addressed at various levels: from heat transfer into the soil to heat transport within the heat exchanger and the absorber pipes, investigating the role of design geometry, quantifying thermal interactions in multiple borehole fields etc.…”

Section: Introductionmentioning

confidence: 99%

Energy Pile Field Simulation in Large Buildings: Validation of Surface Boundary Assumptions

2019

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As the energy efficiency demands for future buildings become increasingly stringent, preliminary assessments of energy consumption are mandatory. These are possible only through numerical simulations, whose reliability crucially depends on boundary conditions. We therefore investigate their role in numerical estimates for the usage of geothermal energy, performing annual simulations of transient heat transfer for a building employing a geothermal heat pump plant and energy piles. Starting from actual measurements, we solve the heat equations in 2D and 3D using COMSOL Multiphysics and IDA-ICE, discovering a negligible impact of the multiregional ground surface boundary conditions. Moreover, we verify that the thermal mass of the soil medium induces a small vertical temperature gradient on the piles surface. We also find a roughly constant temperature on each horizontal cross-section, with nearly identical average values when either integrated over the full plane or evaluated at one single point. Calculating the yearly heating need for an entire building, we then show that the chosen upper boundary condition affects the energy balance dramatically. Using directly the pipes’ outlet temperature induces a 54% overestimation of the heat flux, while the exact ground surface temperature above the piles reduces the error to 0.03%.

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“…Heat exchange processes occurring in boreholes are object of continuous studies from many different sides; a more refined design can reduce installation costs and improve heat transfer and heat pump efficiency (see for instance the reviews [9,10] and references quoted therein). Specifically, the physical processes involved can be addressed at various levels: from heat transfer into the soil to heat transport within the heat exchanger and the absorber pipes, investigating the role of design geometry, quantifying thermal interactions in multiple borehole fields etc.…”

Section: Introductionmentioning

confidence: 99%

Energy Pile Field Simulation in Large Buildings: Validation of Surface Boundary Assumptions

Ferrantelli

Fadejev

Kurnitski

2019

Preprint

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As the energy efficiency demands for future buildings become increasingly stringent, preliminary assessments of energy consumption are mandatory. These are possible only through numerical simulations, whose reliability crucially depends on boundary conditions. We therefore investigate their role in numerical estimates for the usage of geothermal energy, performing annual simulations of transient heat transfer for a building employing a geothermal heat pump plant and energy piles. Starting from actual measurements, we solve the heat equations in 2D and 3D using COMSOL Multiphysics and IDA-ICE, and discover a negligible impact of the multiregional ground surface boundary conditions. Moreover, we verify that the thermal mass of the soil medium induces a small vertical temperature gradient on the piles surface. We also find a roughly constant temperature on each horizontal cross-section, with nearly identical values if the average temperature is integrated over the full plane or evaluated at one single point. Calculating the yearly heating need for an entire building we then show that the chosen upper boundary condition affects the energy balance dramatically. Using directly the pipes’ outlet temperature induces a 54% overestimation of the heat flux, while the exact ground surface temperature above the piles reduces the error to 0.03%.

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Analysis and design methods for energy geostructures

Cited by 84 publications

References 70 publications

A Model of a Diaphragm Wall Ground Heat Exchanger

A Model of a Diaphragm Wall Ground Heat Exchanger

Energy Pile Field Simulation in Large Buildings: Validation of Surface Boundary Assumptions

Energy Pile Field Simulation in Large Buildings: Validation of Surface Boundary Assumptions

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