Drilling Deeper in Shallow Geoexchange Heat Pump Systems—Thermogeological, Energy and Hydraulic Benefits and Restraints
In the last decade, due to climate change concerns and new environmental regulations in the EU, there was a tremendous rise in installed heat pump systems in new homes and buildings. The majority of these installed units are related to air-source heat pumps, as they offer a good trade-off between ca...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-09-01
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| Series: | Energies |
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| Online Access: | https://www.mdpi.com/1996-1073/16/18/6577 |
| _version_ | 1797580393146220544 |
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| author | Tomislav Kurevija Marija Macenić Martina Tuschl |
| author_facet | Tomislav Kurevija Marija Macenić Martina Tuschl |
| author_sort | Tomislav Kurevija |
| collection | DOAJ |
| description | In the last decade, due to climate change concerns and new environmental regulations in the EU, there was a tremendous rise in installed heat pump systems in new homes and buildings. The majority of these installed units are related to air-source heat pumps, as they offer a good trade-off between capital and operating expenses. However, when analysing heating and cooling heat pump systems from the primary energy consumption and ecological aspects, groundwater and shallow geothermal heat pump systems offer superior efficiency, compared to all market-available thermo-technical systems today. In the last decade, ground-source systems have seen some technological improvement by employing new borehole heat exchanger designs, such as piping with internal fins and a wider diameter (so called Turbocollector) to enhance the heat transfer between fluid and rock, as well as to reduce the pressure drop in the system. Furthermore, the process of drilling deeper offers higher ground temperatures and consequently higher seasonal performance factors in the heating cycle, due to the effect of the geothermal gradient. Nevertheless, although deeper boreholes provide better heat extraction rates per meter during the heat pump heating cycle, at the same time, it reduces heat rejection rates during the heat pump cooling cycle. The objective of this paper is to analyse and evaluate benefits and downsides of a new approach in the heat pump system design with deeper borehole heat exchangers of up to 300 m, comparing it to the traditional design of double-loop exchangers with 100 m depth. The geothermal borehole grid design simulation model, along with heat extraction and rejection, is performed on a yearly basis. The results are showing that the benefits of shallow geothermal boreholes, from the hydraulic and thermodynamic point of view, still dominate over deeper solutions. |
| first_indexed | 2024-03-10T22:49:19Z |
| format | Article |
| id | doaj.art-84ddb91f3d054fb984d9c9414e60ac0f |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-03-10T22:49:19Z |
| publishDate | 2023-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-84ddb91f3d054fb984d9c9414e60ac0f2023-11-19T10:27:08ZengMDPI AGEnergies1996-10732023-09-011618657710.3390/en16186577Drilling Deeper in Shallow Geoexchange Heat Pump Systems—Thermogeological, Energy and Hydraulic Benefits and RestraintsTomislav Kurevija0Marija Macenić1Martina Tuschl2Faculty of Mining, Geology and Petroleum Engineering, University of Zagreb, 10000 Zagreb, CroatiaFaculty of Mining, Geology and Petroleum Engineering, University of Zagreb, 10000 Zagreb, CroatiaCroatian Hydrocarbon Agency, 10000 Zagreb, CroatiaIn the last decade, due to climate change concerns and new environmental regulations in the EU, there was a tremendous rise in installed heat pump systems in new homes and buildings. The majority of these installed units are related to air-source heat pumps, as they offer a good trade-off between capital and operating expenses. However, when analysing heating and cooling heat pump systems from the primary energy consumption and ecological aspects, groundwater and shallow geothermal heat pump systems offer superior efficiency, compared to all market-available thermo-technical systems today. In the last decade, ground-source systems have seen some technological improvement by employing new borehole heat exchanger designs, such as piping with internal fins and a wider diameter (so called Turbocollector) to enhance the heat transfer between fluid and rock, as well as to reduce the pressure drop in the system. Furthermore, the process of drilling deeper offers higher ground temperatures and consequently higher seasonal performance factors in the heating cycle, due to the effect of the geothermal gradient. Nevertheless, although deeper boreholes provide better heat extraction rates per meter during the heat pump heating cycle, at the same time, it reduces heat rejection rates during the heat pump cooling cycle. The objective of this paper is to analyse and evaluate benefits and downsides of a new approach in the heat pump system design with deeper borehole heat exchangers of up to 300 m, comparing it to the traditional design of double-loop exchangers with 100 m depth. The geothermal borehole grid design simulation model, along with heat extraction and rejection, is performed on a yearly basis. The results are showing that the benefits of shallow geothermal boreholes, from the hydraulic and thermodynamic point of view, still dominate over deeper solutions.https://www.mdpi.com/1996-1073/16/18/6577deep borehole heat exchangerline source modelheat extraction and rejection ratesgeoexchange heat pump system |
| spellingShingle | Tomislav Kurevija Marija Macenić Martina Tuschl Drilling Deeper in Shallow Geoexchange Heat Pump Systems—Thermogeological, Energy and Hydraulic Benefits and Restraints Energies deep borehole heat exchanger line source model heat extraction and rejection rates geoexchange heat pump system |
| title | Drilling Deeper in Shallow Geoexchange Heat Pump Systems—Thermogeological, Energy and Hydraulic Benefits and Restraints |
| title_full | Drilling Deeper in Shallow Geoexchange Heat Pump Systems—Thermogeological, Energy and Hydraulic Benefits and Restraints |
| title_fullStr | Drilling Deeper in Shallow Geoexchange Heat Pump Systems—Thermogeological, Energy and Hydraulic Benefits and Restraints |
| title_full_unstemmed | Drilling Deeper in Shallow Geoexchange Heat Pump Systems—Thermogeological, Energy and Hydraulic Benefits and Restraints |
| title_short | Drilling Deeper in Shallow Geoexchange Heat Pump Systems—Thermogeological, Energy and Hydraulic Benefits and Restraints |
| title_sort | drilling deeper in shallow geoexchange heat pump systems thermogeological energy and hydraulic benefits and restraints |
| topic | deep borehole heat exchanger line source model heat extraction and rejection rates geoexchange heat pump system |
| url | https://www.mdpi.com/1996-1073/16/18/6577 |
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