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Constraining the heat transfer coefficient of rock fractures
- Source :
- Renewable Energy. 177:433-447
- Publication Year :
- 2021
- Publisher :
- Elsevier BV, 2021.
-
Abstract
- Estimating the heat transfer in deep underground geothermal systems is a challenging task. The concept of explicitly describing the heat transfer between phases has been shown superior to the conventional approach but the heat transfer coefficient of fractures is still ambiguous. In this work, a definition of the lower and upper bound of the heat transfer coefficient between rock and flowing fluid in a single rock fracture is derived and validated with almost 250 experiments from other studies. The resulting values range between 8 and 260 W/m2 °C, with upper bounds roughly a factor 10 larger. Further, as shown in this work, the assumption of local thermal equilibrium can result in lower production temperatures than the assumption of heat transfer between phases depending on reservoir conditions. A dimensionless number is derived to distinct those cases and to determine the lower limit of the outflow temperature in any scenario. The results of this work enable a quantification of the value range of the heat transfer coefficient from laboratory experiments and allow a tabulation of the heat transfer coefficient for all kind of scenarios. The presented results can be used in discrete fracture models for an improved prognosis of production temperatures.
- Subjects :
- Thermal equilibrium
Work (thermodynamics)
Materials science
060102 archaeology
Renewable Energy, Sustainability and the Environment
business.industry
020209 energy
Geothermal energy
06 humanities and the arts
02 engineering and technology
Heat transfer coefficient
Mechanics
Upper and lower bounds
Heat transfer
0202 electrical engineering, electronic engineering, information engineering
Fracture (geology)
0601 history and archaeology
business
Geothermal gradient
Subjects
Details
- ISSN :
- 09601481
- Volume :
- 177
- Database :
- OpenAIRE
- Journal :
- Renewable Energy
- Accession number :
- edsair.doi...........145a2cf5d3cf9a99f5aae77b9f39110b