Heat extraction calculations for deep coaxial borehole heat exchangers: matrix analytical approach

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985891%3A_____%2F23%3A00577638" target="_blank" >RIV/67985891:_____/23:00577638 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216208:11320/23:10473624

Výsledek na webu

<a href="https://doi.org/10.1093/gji/ggad367" target="_blank" >https://doi.org/10.1093/gji/ggad367</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1093/gji/ggad367" target="_blank" >10.1093/gji/ggad367</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Heat extraction calculations for deep coaxial borehole heat exchangers: matrix analytical approach

Popis výsledku v původním jazyce

Deep boreholes represent a source of clean energy. Therefore, effective calculations of potential extraction of heat from boreholes for realistic models of the Earth’s crust with variable thermal conductivity and diffusivity are needed. We deal with heat extraction in a quasi-steady state from coaxial boreholes where downward and upward flows of pumped fluid (water) are separated by an inner pipe and connected only at the bottom. We first obtain theoretical estimates of heat extraction for a thermally isolated inner pipe and a model of the ground with constant thermal diffusivity and conductivity. Then, we develop a new analytical matrix method for a general layered ground model that enables us to include depth-dependent ground properties as well as heat exchange between the downward and upward flows of fluid in the borehole. Our straightforward and fast approach is thus suitable for various parametric studies or as a tool for benchmarks of numerical software. A key role in heat extraction from coaxial boreholes is played by the inner-pipe thermal resistance. We apply our method to the parametric study showing the dependence of pumped water temperature and total heat extraction from the borehole on realistic borehole geometries under different amounts of water pumping. The calculations are performed for a 3 km deep borehole as the representative of present deep boreholes used for extraction of geothermal energy and for a 10 km deep borehole. Drilling of such a superdeep borehole has just started in China and our results demonstrate potential limits of geothermal energy extraction from such great depths.

Název v anglickém jazyce

Heat extraction calculations for deep coaxial borehole heat exchangers: matrix analytical approach

Popis výsledku anglicky

Deep boreholes represent a source of clean energy. Therefore, effective calculations of potential extraction of heat from boreholes for realistic models of the Earth’s crust with variable thermal conductivity and diffusivity are needed. We deal with heat extraction in a quasi-steady state from coaxial boreholes where downward and upward flows of pumped fluid (water) are separated by an inner pipe and connected only at the bottom. We first obtain theoretical estimates of heat extraction for a thermally isolated inner pipe and a model of the ground with constant thermal diffusivity and conductivity. Then, we develop a new analytical matrix method for a general layered ground model that enables us to include depth-dependent ground properties as well as heat exchange between the downward and upward flows of fluid in the borehole. Our straightforward and fast approach is thus suitable for various parametric studies or as a tool for benchmarks of numerical software. A key role in heat extraction from coaxial boreholes is played by the inner-pipe thermal resistance. We apply our method to the parametric study showing the dependence of pumped water temperature and total heat extraction from the borehole on realistic borehole geometries under different amounts of water pumping. The calculations are performed for a 3 km deep borehole as the representative of present deep boreholes used for extraction of geothermal energy and for a 10 km deep borehole. Drilling of such a superdeep borehole has just started in China and our results demonstrate potential limits of geothermal energy extraction from such great depths.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

20704 - Energy and fuels

Projekt

<a href="/cs/project/TP01010055" target="_blank" >TP01010055: Geofyzika, geotechnika, geomateriály, geotermální energie pro praxi</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2023

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Geophysical Journal International

ISSN

0956-540X

e-ISSN

1365-246X

Svazek periodika

235

Číslo periodika v rámci svazku

3

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

16

Strana od-do

2323-2338

Kód UT WoS článku

001124759000011

EID výsledku v databázi Scopus

2-s2.0-85175449383