Model for economic evaluation of closed-loop geothermal systems based on net present value

Applied Thermal Engineering, Год журнала: 2023, Номер 231, С. 121008 - 121008

Опубликована: Июнь 17, 2023

Язык: Английский

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Advances in ground heat exchangers for space heating and cooling: Review and perspectives

Energy and Built Environment, Год журнала: 2022, Номер 5(2), С. 255 - 269

Опубликована: Окт. 4, 2022

As a renewable energy source, geothermal has been widely used to provide space heating and cooling for buildings. The thermal performance of ground heat exchanger (GHE) is significant the operating efficiency source pump (GSHP) systems. This paper presents comprehensive review developments advances three kinds GHE, including vertical borehole GHE (VBGHE), Pile (PGHE), deep (DBGHE) which are currently popular in larger GSHP Firstly, analytical models proposed analyze transfer process VBGHE with different geological conditions summarized, such as homogenous or heterogeneous ground, without groundwater advection. Numerical short-time step measures improve also reviewed. Secondly, summary research PGHE provided, includes PGHE, effects geometric structure, operation modes, pile spacing, use phase change material (PCM), properties PCM, thermo-mechanical behavior and/or PGHE. flow direction velocity on summarized brief. Lastly, DBGHEs, i.e., coaxial (DCGHE), U-bend (DUGHE) super-long gravity pipe (SLGHP), physical bases elaborated their advantages disadvantages described. Advances numerical modelling improving model calculation speed DCBHE, DCBHE array, DUBHE summarized. provides meaningful reference further study GHEs.

Язык: Английский

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Investigating scalability of deep borehole heat exchangers: Numerical modelling of arrays with varied modes of operation

Renewable Energy, Год журнала: 2022, Номер 202, С. 442 - 452

Опубликована: Ноя. 23, 2022

Deep Borehole Heat Exchangers (DBHEs) are a potentially important method of developing geothermal resources through closed-loop systems for carbon neutral, spatial heating. Past research has primarily focused on single-well systems, with few investigating arrays multiple DBHEs as extracting more thermal energy. In this study, series were modelled using OpenGeoSys software, the aim understanding influence array geometry, inter-borehole spacing and mode operation performance system efficiency. software is finite-element model which solves fluxes wellbore surrounding rock dual-continuum method. Simulations undertaken lifetime an (20 years) modes testing 1) long-term constant heat load application 2) intermittent 6 months extraction followed by recovery period. Results indicate geometry had significant impact performance. For long term 50 kW per DBHE, minimal required line square should be 40 30 m. When considering operation, periods allow replenishment around borehole, meaning smaller can utilised.

Язык: Английский

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Heat transfer performance of deep borehole heat exchanger with different operation modes

Renewable Energy, Год журнала: 2022, Номер 193, С. 645 - 656

Опубликована: Май 14, 2022

Язык: 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, Год журнала: 2023, Номер 117, С. 102888 - 102888

Опубликована: Дек. 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.

Язык: Английский

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Experimental and numerical simulation research on heat transfer performance of coaxial casing heat exchanger in 3500m-deep geothermal well in Weihe Basin

Geothermics, Год журнала: 2023, Номер 109, С. 102658 - 102658

Опубликована: Янв. 20, 2023

Язык: 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, Год журнала: 2023, Номер 16(6), С. 2677 - 2677

Опубликована: Март 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).

Язык: Английский

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

Geothermal Energy, Год журнала: 2024, Номер 12(1)

Опубликована: Июнь 10, 2024

Язык: Английский

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Thermal performance of medium-deep U-type borehole heat exchanger based on a novel numerical model considering groundwater seepage

Renewable Energy, Год журнала: 2024, Номер 222, С. 119988 - 119988

Опубликована: Янв. 9, 2024

Язык: Английский

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Optimization of a district heating system coupled with a deep open-loop geothermal well and heat pumps

Renewable Energy, Год журнала: 2024, Номер 223, С. 119991 - 119991

Опубликована: Янв. 10, 2024

Язык: Английский

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