| 1. |
- Adl-Zarrabi, Bijan, 1959, et al.
(författare)
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Ground Source De-Icing and Snow Melting Systems for Infrastructure
- 2023
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Ingår i: Transportation Research Procedia. - 2352-1465 .- 2352-1457. ; 72, s. 1621-1628
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Konferensbidrag (refereegranskat)abstract
- Thermal de-icing and snow melting methods to control winter conditions on surfaces of transport infrastructure offer several advantages compared to conventional techniques. These include the automated control of safe surface conditions, avoidance of chemicals and their environmental impact and prolongation of the life span of the infrastructure. Hydronic heat transfer systems can take advantage of collection of solar energy mainly during summertime and seasonal storage of thermal energy by geothermal heat exchange. Making use of these renewable resources in combination with energy storage enables savings in primary energy. In June 2021, the International Energy Agency (IEA), initiated a project related to utilization of ground thermal energy sources for de-icing of surfaces in transport infrastructures. The present paper gives a first overview of the project goals and methods.
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| 2. |
- Gehlin, S E A, et al.
(författare)
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Influence on thermal response test by groundwater flow in vertical fractures in hard rock
- 2003
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Ingår i: Renewable Energy. - 0960-1481 .- 1879-0682. ; 28:14, s. 2221-2238
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Tidskriftsartikel (refereegranskat)abstract
- In this paper different approaches to groundwater flow and its effect in the vicinity of a borehole ground heat exchanger are discussed. The common assumption that groundwater flow in hard rock may be modelled as a homogeneous flow in a medium with an effective porosity is confronted and models for heat transfer due to groundwater flow in fractures and fracture zones are presented especially from a thermal response test point of view. The results indicate that groundwater flow in fractures even at relatively low specific flow rates may cause significantly enhanced heat transfer, although a continuum approach with the same basic assumptions would suggest otherwise. (C) 2003 Elsevier Science Ltd. All rights reserved.
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| 3. |
- Gehlin, S E A, et al.
(författare)
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The influence of the thermosiphon effect on the thermal response test
- 2003
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Ingår i: Renewable Energy. - 0960-1481 .- 1879-0682. ; 28:14, s. 2239-2254
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Tidskriftsartikel (refereegranskat)abstract
- The issue of natural and forced groundwater movements, and its effect on the performance of ground heat exchangers is of great importance for the design and sizing of borehole thermal energy systems (BTESs). In Scandinavia groundwater filled boreholes in hard rock are commonly used. In such boreholes one or more intersecting fractures provide a path for groundwater flow between the borehole and the surrounding rock. An enhanced heat transport then occurs due to the induced convective water flow, driven by the volumetric expansion of heated water. Warm groundwater leaves through fractures in the upper part of the borehole while groundwater of ambient temperature enters the borehole through fractures at larger depths. This temperature driven flow is referred to as thermosiphon, and may cause considerable increase in the heat transport from groundwater filled boreholes. The thermosiphon effect is connected to thermal response tests, where the effective ground thermal conductivity is enhanced by this convective transport. Strong thermosiphon effects have frequently been observed in field measurements. The character of this effect is similar to that of artesian flow through boreholes. (C) 2003 Elsevier Science Ltd. All rights reserved.
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| 4. |
- Spitler, Jeff, 1961, et al.
(författare)
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Thermal response testing for ground source heat pump systems - An historical review
- 2015
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Ingår i: Renewable and Sustainable Energy Reviews. - : Elsevier BV. - 1879-0690 .- 1364-0321. ; 50, s. 1125-1137
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Forskningsöversikt (refereegranskat)abstract
- When designing ground heat exchangers used with ground source heat pump systems, a critical design property is the thermal conductivity of the ground. Thermal response tests are used to measure the site-specific thermal conductivity and are also used to measure the thermal resistance of a borehole heat exchanger as installed. Thermal response tests are commonly used today for design of multiple borehole ground heat exchangers, where knowledge of the ground thermal properties can help avoid undersizing of ground heat exchangers, leading to poor system performance, and oversizing of ground heat exchangers, leading to overly costly systems. This review covers the development of the mathematical and numerical analysis procedures, development of the hardware and test procedures, and validation of the results. We take a historical perspective, going as far back as Lord Kelvin's treatment of transient heat conduction problems in the 1880s, further development of which allowed analysis of conductivity measurements from transient needle probes by the 1950s. We focus on development of test rigs and test procedures in the 1980s and 1990s and validation of the measurements. More recent developments are covered throughout the review.
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