Experimental study of mechanical properties of hot dry granite under thermal-mechanical couplings

Geothermics, Journal Year: 2024, Volume and Issue: 119, P. 102974 - 102974

Published: March 1, 2024

Language: Английский

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Comparison of the thermal and hydraulic performance of single U-tube, double U-tube and coaxial medium-to-deep borehole heat exchangers

Geothermics, Journal Year: 2023, Volume and Issue: 117, P. 102888 - 102888

Published: Dec. 7, 2023

Decarbonisation of heat is essential in curbing carbon dioxide emissions and can be achieved through the use geothermal systems. Recently, single-well, closed-loop, deep borehole exchangers, using a coaxial design, have become focus attention, partly due to potential repurpose existing infrastructure (such as oil gas wells); however, few investigated for other types exchanger middle-deep Therefore, this study, comprehensive numerical analysis was undertaken OpenGeoSys software investigate thermal hydraulic performance coaxial, single U-tube double exchangers (MDBHEs). The purpose paper test maximum operational depth each type pipe configuration wells been completed depths exceeding 500 m single/double configurations. best performing MDBHEs should minimise parasitic losses, whilst maximising output. Furthermore, ground sourced pumps require electricity; therefore, at times where electricity prices are high (and drilling costs minimised) it may more beneficial utilise encounter greater temperatures. Results indicate that provide terms specific extraction lowest pressure/parasitic losses. Double similar but significantly pressure losses across all simulations, which translates pumping power costs. Single demonstrate poorest At end 25-year base case scenario 800 MDBHE, configurations, with fluid circulation rate 5 L/s, provided rates 39.1 W/m, 32.8 36.0 respectively, inlet temperature set constant °C. For these were estimated 85 kPa (coaxial), 1.46 MPa (single U-tube) 423 (double U-tube)—the value being close nominal 16 bar (1.6 Mpa) rating SDR11 density polyethylene pipe. Further parametric also undertaken, investigating depth, flow rate, rock conductivity, diameter shank spacing.

Language: Английский

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Investigating the Influence of Groundwater Flow and Charge Cycle Duration on Deep Borehole Heat Exchangers for Heat Extraction and Borehole Thermal Energy Storage

Energies, Journal Year: 2023, Volume and Issue: 16(6), P. 2677 - 2677

Published: March 13, 2023

Decarbonisation of heat is essential to meeting net zero carbon targets; however, fluctuating renewable resources, such as wind or solar, may not meet peak periods demand. Therefore, methods underground thermal energy storage can aid in storing low demand be exploited when required. Borehole (BTES) an important technology surplus and the efficiency systems strongly influenced by groundwater flow. In this paper, effect flow on a single deep borehole exchanger (DBHEs) was modelled using OpenGeoSys (OGS) software test impact varying regional Darcy velocities performance extraction BTES. It anticipated that infrastructure ex-geothermal exploration oil gas development wells approaching end life could repurposed. These encounter fluid subsurface well BTES has previously been investigated. Higher increase DBHE operating extract only for heating season 6 months. This due reduced cooling rocks proximity replenishes which removed from rock volume around (this also equivalently thought “coolth” being transported away plume). When testing with other parameters 920 m length conductivity 2.55 W/(m·K), it observed larger velocity (1e-6 m/s) output up 28 kW comparison there no contrast, inhibits depletes store, reducing 13% models advective transfer subsurface. The highest 1e-6 m/s shown most influence BTES; likelihood occurring regionally, at depth over 1 km unlikely. study tested temporal resolutions charge cyclicity. Shorter allow greater recovery (c. 34% injected recovered month charge, opposed <17% months charge).

Language: Английский

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A comprehensive review of deep borehole heat exchangers (DBHEs): subsurface modelling studies and applications

Geothermal Energy, Journal Year: 2024, Volume and Issue: 12(1)

Published: June 10, 2024

Language: Английский

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Numerical investigation of the deep borehole heat exchanger in medium-depth geothermal heat pump system for building space heating

Energy and Buildings, Journal Year: 2024, Volume and Issue: 304, P. 113874 - 113874

Published: Jan. 3, 2024

Language: Английский

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Assessing the technical potential for underground thermal energy storage in the UK

Renewable and Sustainable Energy Reviews, Journal Year: 2024, Volume and Issue: 199, P. 114545 - 114545

Published: May 14, 2024

Heating and cooling both make up a large part of the total energy demand in UK; long-term seasonal thermal storage (STES) can address temporal imbalances between varying supply heat to buildings processes. Underground (UTES) play role decarbonisation by storing waste from space cooling, refrigeration, data processing, industrial processes, harvested summer solar or even generated surplus renewable (solar wind) electricity with fluctuating supply. This paper evaluates range UTES technologies UK context addresses geological suitability, capacity, low-carbon sources, surface sources demand. review concludes that there is significant potential for aquifer (ATES) borehole (BTES) systems, coinciding Therefore, uptake technology will help achieve net-zero carbon neutral targets 2050. There also scope utilise within existing subsurface infrastructure. are 464 oil gas wells which could be repurposed upon end life using different technologies. However, repurposing needs further evaluation; deep single well BTES systems have high area volume ratio storage, reducing efficiency such ATES limited issues associated contaminants. 23,000 abandoned mines underlay ∼25 % UKs population utilised minewater (MTES).

Language: Английский

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Heating and storage of medium-deep borehole heat exchangers: Analysis of operational characteristics via an optimized analytical solution model

Journal of Energy Storage, Journal Year: 2024, Volume and Issue: 90, P. 111760 - 111760

Published: May 3, 2024

Language: Английский

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A novel geothermal pavement ice and snow melting system with reversible loop heat pipes to eliminate underground thermal imbalance

Applied Thermal Engineering, Journal Year: 2025, Volume and Issue: unknown, P. 126052 - 126052

Published: Feb. 1, 2025

Language: Английский

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Repurposing a Geothermal Exploration Well as a Deep Borehole Heat Exchanger: Understanding Long-Term Effects of Lithological Layering, Flow Direction, and Circulation Flow Rate

Sustainability, Journal Year: 2023, Volume and Issue: 15(5), P. 4140 - 4140

Published: Feb. 24, 2023

In the drive to achieve net-zero carbon emissions, decarbonisation of heating is essential. This can be facilitated by geothermal energy, but drilling wells associated with high risks and costs. The use preexisting (e.g., exhausted hydrocarbon or failed exploration boreholes) offsets this cost while potentially turning liabilities into assets. Newcastle Science Central Deep Geothermal Borehole (NSCDGB) a well that was drilled target Carboniferous Fell Sandstone Formation at 1418.5 1795 m depth. However, low hydraulic conductivities prevented development as conventional “wet” abstraction well; therefore, new alternative methods are being explored. work investigates repurposing NSCDGB deep borehole heat exchanger (DBHE), focusing on sustainable operation system in long term employing constant load designed contribute local buildings network. Numerical modelling undertaken using OpenGeoSys software analyse thermal performance system. Both homogeneous heterogeneous models were developed compare influence lithological layering contrast (nonstratified) subsurface geological model. Results from simulations DBHE depth 922 show 50-kW supported for lifetime 25 years. corresponds 65-kW building when coupled pump coefficient 4.33. Thus, could meet up 72% demand adjacent urban sciences building. Rather than purely hypothetical case study, considers real existing borehole, cluster which make heat. Heterogeneity, has been considered first time site, exhibits minor impact comparison simulation results. Flow direction mass flow rate also exhibited small effects performance, whereas if repurposed increased depths, increased. study coaxial site considering long-term rate, heterogeneity, direction. evaluates feasibility an exploratory UK used low-carbon source space heating, thus converting potential “green energy”

Language: Английский

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Technical review on coaxial deep borehole heat exchanger

Geomechanics and Geophysics for Geo-Energy and Geo-Resources, Journal Year: 2023, Volume and Issue: 9(1)

Published: Sept. 23, 2023

Abstract This review paper summarizes recent developments regarding geothermal exploitation using coaxial deep borehole heat exchangers (DBHE). Specifically, this study focuses on field tests, analytical and semi-analytical approaches, numerical simulations. First, tests applications of DBHE are summarized future work for the is suggested. Then, ongoing modeling approaches evaluated capability incapability describing physical behaviors. Lastly, key factors design discussed based collected results. Regarding should focus more (1) long-term performance; (2) effect groundwater flow within formation fractures; (3) technology larger diameter boreholes; (4) new cheap materials insulated inner pipe; (5) treatment fluid, pipe wall, different working fluid; (6) economic analysis DBHE-based power plant. As methods simulations, it important to consider dependence fluid properties pressure temperature. Besides, verification calibration empirical models fluids other than water such as CO 2 be performed laboratory tests. Different pump parameters optimized obtain maximum thermal a DBHE, an recommended by many researchers. An intermittent pattern could realistic when DBHE. To further improve performance continuous research enhance transfer still important.

Language: Английский

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