Mechanical stability of granite as thermal energy storage material: An experimental investigation

Li, Baiyi; Feng, Jie; Xiao, Meng; Ning, Pai

doi:10.1016/j.engfracmech.2019.02.008

Cited by 39 publications

(20 citation statements)

References 20 publications

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“…Thermal Fatigue Test (TF): The second experiment aimed at knowing the effect of thermal fatigue by temperature cycles. The samples went through 5 cycles of heating at 200 • C in a furnace "Thermo scientific led M 110" with a gradient of 5 • C•min −1 to ensure the cracking [16,[54][55][56][57]. As in TT, the samples were maintained at the set temperature for 2 h and the cooling down was slow with a rate of about 0.5-1 • C•min −1 .…”

Section: Methodsmentioning

confidence: 99%

The Use of Infrared Thermography on the Measurement of Microstructural Changes of Reservoir Rocks Induced by Temperature

et al. 2021

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A variation of temperature produces a change in the microstructure of the rock due to the mineral thermal expansion and its residual strain. Depending on the temperature cycle and texture, microstresses may lead to the development of preexistent cracks or the creation of a new and irreversible cracking. The effect of temperature on reservoir rocks is an important topic since it conditions the permeability and the fluid flow. Two main questions arise from this: the first is if an irreversible cracking threshold is attained in the reservoir rocks at low temperature geothermal systems (around 100 °C); the second one is about the influence of thermal fatigue by the repetition of heating–cooling cycles on the different rock types. To answer these questions, four reservoir rocks (chalk, sandstone, fresh granite, and weathered granite) were submitted to two different thermal regimes. The first test was conceived to detect the irreversible cracking threshold, and for that, the rocks were submitted to progressive heating (90°, 100°, 110°, 120°, and 130 °C). The second test consisted of doing cycles of fast heating of the samples up to 200 °C. The microstructure variation was assessed by means of a scanning electron microscope, mercury porosimetry, and capillary water uptake combined with passive infrared thermography. Infrared thermography is an emerging tool in the field of rock study, used to detect water masses or determine thermal properties. The water transfer during the capillary tests of the rocks, before and after the tests, was monitored with this technique. In addition, the cooling rate index, a non-destructive parameter to detect cracking development, was calculated. The results made it possible to differentiate the behaviours in relation to the rock type, with a chalk and a weathered granite less susceptible to thermal stresses than a fresh granite and sandstone. In addition, infrared thermography resulted in being a very useful indirect technique to detect the changes on the surface, although they do not always correlate to the bulk microstructural changes.

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Section: Methodsmentioning

confidence: 99%

The Use of Infrared Thermography on the Measurement of Microstructural Changes of Reservoir Rocks Induced by Temperature

et al. 2021

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“…Samples were ground and polished using a lapping machine. In order to eliminate the effect of water saturation, all the samples were baked for 2 h at a 2 Geofluids temperature of 105°C in a resistance furnace, retaining no water saturation [38]. The samples were cooled naturally to room temperature (20°C).…”

Section: Methodsmentioning

confidence: 99%

Experimental and Numerical Modelling of Nonlinear Flow Behavior in Single Fractured Granite

Zhou

et al. 2019

Geofluids

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In this study, the hydromechanical behavior was experimentally investigated by conducting fracture geometry evolution-based gas flow tests on single fractured granite. The traditional fracture roughness value (Rp) of a single surface cannot adequately explain the intrinsic permeability in multiple samples. Instead, the permeability is better explained by aperture distribution, and it is positively correlated with the mean aperture size. The permeability is also affected by a combination of contact area and void space under changing confining stress. The average embedded depth increases rapidly under low-loading stress (less than 8 MPa) and slowly under high-loading stress (higher than 8 MPa). A simplified Hertz contact model was used to fit the experimental data. The model uses the reciprocal of the standard deviation of the aperture as the average curvature radius of the fracture. Good agreement was found between the experimental and theoretical results. A modified smooth parallel-plate model to describe flow friction in fractures was developed, which takes fracture contact and void space into account. A new friction model was also developed that takes both the nonlinear effect and the influence of fracture relative roughness into account by multiplying the ideal model by two power-law functions. This new model is effective in predicting the friction factor. Finally, taking into consideration the built permeability, mechanical, and friction models, a nonlinear flow model was proposed. The flow rate can be estimated based on the 3D fracture topography data, the applied loading stress, and the pressure gradient. The influence of four types of aperture distribution on the friction factor was investigated. The results showed that a high mean aperture size would result in a low friction factor. In addition, the influence of the mean aperture size on the friction factor is obvious, even under a very high-loading stress while the effect of the standard deviation is negligible when the loading stress is very high.

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“…It is an effective means to tackle the intermittency problem of renewable energy by storing excessive heat and releasing it later when needed. It is critical to consider the rock bed subjected to cyclic temperature [7][8][9]. Moreover, the periodic temperature stress due to cyclic temperature in a constrained environment acts simultaneously on the rock mass of TES [10].…”

Section: Introductionmentioning

confidence: 99%

Exploratory Experimental Study on the Mechanical Properties of Granite Subjected to Cyclic Temperature and Uniaxial Stress

Zhao

Jin

2020

Energies

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This paper investigates the variation of mechanical properties of granite during temperature and stress cycling, which is an important part of evaluating the long-term thermal and mechanical stability of thermal energy storage. Cyclic temperature and loading tests were conducted where the upper limit of cyclic temperature was 100-600 • C, and the upper stress limits were 70% and 85% of the average uniaxial compressive strength (UCS) at the corresponding temperature. The response of stress-strain characteristics of the granite samples to changes in temperature, and cyclic load upper limit, while the number of temperature and loading cycles was comprehensively analyzed. The results show that the temperature and stress cycles have significant effects on the mechanical properties of granite (i.e., stress-strain curve, strength, elastic modulus, and deformation). The elastic modulus of the sample during loading increases gradually. The strain corresponding to the upper loads of the granite samples decreases with an increasing number of cycles. Additionally, the UCS of samples after 10 cycles at 70% loading stress is greater than that at 85% loading stress. The mechanical properties of samples change dramatically during the first and second cycles at 85% loading stress, whereas at 70% loading stress, the mechanical properties change gradually in the first few cycles, and then tend to stabilize. Cyclic hardening is observed at temperatures below 500 • C, where post cyclic UCS is greater than the uncycled average UCS. This phenomenon requires further research.Energies 2020, 13, 2061 2 of 17 reported the effect of cyclic temperature on the physical and mechanical properties of rocks. Rong et al. [11,12] investigated the influence of thermal cycling on the physical and mechanical properties of rock (i.e., marble and granite) through a uniaxial compression test and conducted microscopic observations to investigate the thermal damage of rock sample induced by the treatment of different thermal cycles. Battaglia et al. [15] measured the linear thermal expansion of marbles subjected to thermal cycles utilizing a high-sensitivity apparatus. Lin et al. [16] investigated the variation of residual strain and micro-crack density of granite with cyclic temperature in the range of 600 • C, and explained the mechanism of permanent deformation caused by micro-cracks from the microscopic perspective. Fang [18] analyzed and compared the effects of mechanical properties of marble subjected to thermal treatment and thermal cycling. They showed that the physical and mechanical properties of rock samples deteriorate gradually with an increasing number of temperature cycles. Further, other researchers considered that the deterioration of the mechanical properties of building materials and engineering structures in cold regions with harsh climatic conditions was due to freeze-thaw cycles [19][20][21].Most of the earlier studies on the effect of cyclic loading on the mechanical properties of rocks did not consider the effect of temperature, i....

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Mechanical stability of granite as thermal energy storage material: An experimental investigation

Cited by 39 publications

References 20 publications

The Use of Infrared Thermography on the Measurement of Microstructural Changes of Reservoir Rocks Induced by Temperature

The Use of Infrared Thermography on the Measurement of Microstructural Changes of Reservoir Rocks Induced by Temperature

Experimental and Numerical Modelling of Nonlinear Flow Behavior in Single Fractured Granite

Exploratory Experimental Study on the Mechanical Properties of Granite Subjected to Cyclic Temperature and Uniaxial Stress

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