Model for Ground Temperature Estimations and Its Impact on Horizontal Ground Heat Exchanger Design

Xing, Lu; Spitler, Jeffrey D.; Li, Liheng; Hu, Pingfang

doi:10.22488/okstate.17.000511

Cited by 2 publications

(2 citation statements)

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“…Water content depends on meteorological and environmental events (such as rainfall, solar radiation, albedo, fluctuations in air temperature, vegetation cover, and evapotranspiration [162][163][164][165]) and variations of climatic data (particularly air temperature and rainfall) can affect the moisture transfer in soils. Even if this effect is mainly evident in the very shallow part of the soil and it reduces with depth, it can produce variations on soil thermal properties that significantly affect the performance of GSHP systems (particularly horizontal ground exchangers) [166][167][168]. As a reference, a soil saturation degree below 12.5%, above 25%, and over 50%, generates a decrease, an improvement, and an insignificant variation of the performance, respectively [169].…”

Section: Site and Locationsmentioning

confidence: 99%

Sustainability of Shallow Geothermal Energy for Building Air-Conditioning

2021

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Geothermal heat pumps have a widespread diffusion as they are able to deliver relatively higher energy output than other systems for building air-conditioning. The exploitation of low-enthalpy geothermal energy, however, presents crucial sustainability issues. This review investigates the primary forms of the environmental impact of geothermal heat pumps and the strategies for their mitigation. As life-cycle analyses shows that the highest impacts arise from installation and operation stages, most optimization studies focus on system thermodynamics, aiming at maximizing the energy performance via the optimization in the design of the different components interacting with the ground and serviced building. There are environmental studies of great relevance that investigate how the climate and ground properties affect the system sustainability and map the most suitable location for geothermal exploitation. Based on this review, ground-source heat pumps are a promising technology for the decarbonization of the building sector. However, a sustainable design of such systems is more complex than conventional air-conditioning systems, and it needs a holistic and multi-disciplinary approach to include the broad environmental boundaries to fully understand the environmental consequences of their operation.

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Section: Site and Locationsmentioning

confidence: 99%

Sustainability of Shallow Geothermal Energy for Building Air-Conditioning

2021

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“…Diurnal, monthly and seasonal variations of climatic data, especially air temperature and rainfall, can affect the moisture transfer in soils. Even if their contributions is reduced with increasing depth, the induced variations on soil thermal properties may have significant effects on the performance of the horizontal GSHP system [42][43][44]. According to Leong et al a soil saturation degree below 12.5%, above 25% and in excess of 50% is responsible respectively for a decrease, an improvement and an insignificant variation of the performance [45].…”

Section: Introductionmentioning

confidence: 99%

Factors Influencing the Thermal Efficiency of Horizontal Ground Heat Exchangers

Sipio

Bertermann

2017

Energies

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Abstract:The performance of very shallow geothermal systems (VSGs), interesting the first 2 m of depth from ground level, is strongly correlated to the kind of sediment locally available. These systems are attractive due to their low installation costs, less legal constraints, easy maintenance and possibility for technical improvements. The Improving Thermal Efficiency of horizontal ground heat exchangers Project (ITER) aims to understand how to enhance the heat transfer of the sediments surrounding the pipes and to depict the VSGs behavior in extreme thermal situations. In this regard, five helices were installed horizontally surrounded by five different backfilling materials under the same climatic conditions and tested under different operation modes. The field test monitoring concerned: (a) monthly measurement of thermal conductivity and moisture content on surface; (b) continuous recording of air and ground temperature (inside and outside each helix); (c) continuous climatological and ground volumetric water content (VWC) data acquisition. The interactions between soils, VSGs, environment and climate are presented here, focusing on the differences and similarities between the behavior of the helix and surrounding material, especially when the heat pump is running in heating mode for a very long time, forcing the ground temperature to drop below 0 • C.

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Model for Ground Temperature Estimations and Its Impact on Horizontal Ground Heat Exchanger Design

Abstract: The ground-source heat pump systems are highly efficient and energy saving. Its

Cited by 2 publications

References 12 publications

Sustainability of Shallow Geothermal Energy for Building Air-Conditioning

Sustainability of Shallow Geothermal Energy for Building Air-Conditioning

Factors Influencing the Thermal Efficiency of Horizontal Ground Heat Exchangers

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