Investigation of Flow and Heat Transfer Characteristics in Fractured Granite

Luo, Jun; Qi, Yumeng; Zhao, Qiang; Tan, Long; Xiang, Wei; Rohn, Joachim

doi:10.3390/en11051228

Cited by 16 publications

(5 citation statements)

References 19 publications

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“…Figure 2 shows the physical structure model of heat transfer. Luo et al [35,36] analyzed the heat transfer phenomenon in the flow process, and results showed that heat flow is a process of energy exchange. Therefore, the author divides the heat transfer process into three types: linear, curved, and spiral.…”

Section: Causes Of Formation Of High Ground Temperaturementioning

confidence: 99%

Mechanical Properties and Microstructure of Shotcrete under High Temperature

Liu

Zhao

Zhang³

et al. 2021

Applied Sciences

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High temperature is recognized as one of the extreme environments in the application of shotcrete which significantly deteriorate the performance of shotcrete. This paper reviews the mechanical properties and microstructure of shotcrete under high temperature. First of all, this paper reviews the cause of formation of high ground temperature. Based on these causes, the author establishes a heat transfer model with a spiral shape by introducing a multidimensional morphological formula into the heat conduction process. Then, the paper reviews the influence of high temperature on the mechanical and micro properties of shotcrete, the cooling technology under high temperature, and the optimization research technology of shotcrete. The author discusses the influence of high temperature on the thermal parameters and the deformation of shotcrete from the perspective of thermodynamics. Multiple studies have shown that the irregular movement and disorderly overlapping of molecules in the shotcrete caused by the high temperature environment result in the premature termination of the hydration reaction of cement in shotcrete. Finally, the author suggests the challenges of high-temperature shotcrete in term of the process structure, performance optimization, and application in special engineering fields. The research in this paper intends to give guidance to those conducting shotcrete research under high temperature, and to promote the further development of shotcrete technology.

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Section: Causes Of Formation Of High Ground Temperaturementioning

confidence: 99%

Mechanical Properties and Microstructure of Shotcrete under High Temperature

Liu

Zhao

Zhang³

et al. 2021

Applied Sciences

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“…He et al [13] found that the local heat transfer coefficient (LHTC) distribution mainly depends on the fracture surface roughness, followed by aperture and flow rate. Moreover, Luo et al [14] found that the energy exchange rate increases continuously with the rock temperature, with an effective stress ratio of 1:2. Li et al [15] indicated that the effects of the dissolution reaction on fracture surface morphology exists but it is extremely small for heat transfer.…”

Section: Introductionmentioning

confidence: 99%

Study on Flow and Heat Transfer in Single Rock Fractures for Geothermal Heat Extraction

Li,

Liu,

Liao

2024

Processes

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A full understanding of the fluid flow and heat transfer behaviors within a single fracture is important for geothermal heat extraction. In this study, models of single fractures with varying aperture and inner surface roughness (characterized by fractal dimension) are constructed, and a compound fracture aperture (CFA) is proposed to describe the coupled effect of fracture aperture and inner surface roughness. The effect of the fluid flow Reynolds number on heat transfer was investigated as it ranged from 4.84 to 145.63. The results show that the overall heat transfer coefficient (OHTC) in a single fracture significantly increases with the rise in fluid velocity and the compound fracture aperture. Particularly, the OHTC in a single fracture with an inner surface fractal dimension of 2.09 can be up to 1.215 times that of a parallel flat fracture when the flow velocity reaches 0.18 m/s. Moreover, for a fracture with a smaller CFA, enhancing the fracture aperture plays a decisive role in increasing the OHTC. Aperture emerges as a more sensitive optimization parameter for efficient heat extraction compared to the flow velocity. Meanwhile, based on simulation results, a convective heat transfer correlation equation is derived to provide more accurate estimates of the OHTC in rock fractures with different geometries and morphological features.

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“…These experiments are useful to quantify heat storage considering the thermal conductivity and specific heat capacity values of groundwater and rock matrices (Molson et al 1992 ; Palmer et al 1992 ; Bridger and Allen 2010 ; Luo et al 2017 ; Dassargues 2018 ; de Schepper et al 2019 ). They allow characterization of the thermal retardation within the medium and to highlight the difference of behavior compared to solute tracers (Geiger and Emmanuel 2010 ; Ma and Zheng 2010 ; Rau et al 2012 ; Irvine et al 2015 , 2017 ; Dassargues 2018 ; de la Bernardie et al 2018 ; Luo et al 2018 ; Sarris et al 2018 ; Hoffmann et al 2019 ).…”

Section: Introductionmentioning

confidence: 99%

Heat Tracing in a Fractured Aquifer with Injection of Hot and Cold Water

et al. 2021

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Heat as a tracer in fractured porous aquifers is more sensitive to fracture-matrix processes than a solute tracer. Temperature evolution as a function of time can be used to differentiate fracture and matrix characteristics. Experimental hot (50 • C) and cold (10 • C) water injections were performed in a weathered and fractured granite aquifer where the natural background temperature is 30 • C. The tailing of the hot and cold breakthrough curves, observed under different hydraulic conditions, was characterized in a log-log plot of time vs. normalized temperature difference, also converted to a residence time distribution (normalized). Dimensionless tail slopes close to 1.5 were observed for hot and cold breakthrough curves, compared to solute tracer tests showing slopes between 2 and 3. This stronger thermal diffusive behavior is explained by heat conduction. Using a process-based numerical model, the impact of heat conduction toward and from the porous rock matrix on groundwater heat transport was explored. Fracture aperture was adjusted depending on the actual hydraulic conditions. Water density and viscosity were considered temperature dependent. The model simulated the increase or reduction of the energy level in the fracture-matrix system and satisfactorily reproduced breakthrough curves tail slopes. This study shows the feasibility and utility of cold water tracer tests in hot fractured aquifers to boost and characterize the thermal matrix diffusion from the matrix toward the flowing groundwater in the fractures. This can be used as complementary information to solute tracer tests that are largely influenced by strong advection in the fractures.

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Investigation of Flow and Heat Transfer Characteristics in Fractured Granite

Cited by 16 publications

References 19 publications

Mechanical Properties and Microstructure of Shotcrete under High Temperature

Mechanical Properties and Microstructure of Shotcrete under High Temperature

Study on Flow and Heat Transfer in Single Rock Fractures for Geothermal Heat Extraction

Heat Tracing in a Fractured Aquifer with Injection of Hot and Cold Water

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