Thermal depth profiling of materials for defect detection using hot disk technique

Mihiretie, Besira Mekonnen; Cederkrantz, Daniel; Sundin, Maria; Rosén, Arne; Otterberg, Henrik; Hinton, Åsa; Berg, B. V.; Karlsteen, M.

doi:10.1063/1.4961879

Cited by 10 publications

(3 citation statements)

References 13 publications

(13 reference statements)

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“…During the test, a certain temperature rise was generated by the current passing through the probe, and the heat capacity of the probe was negligible. The heat of the probe diffuses to both sides of the sample at the same time, and the average temperature rise of the probe surface was accurately measured according to the resistance change of the metal sheet of the probe (Gustavsson et al, 1997;Mihiretie et al, 2016). The Hot Disk probe is both a heat source and a temperature sensor.…”

Section: Sample Collection and Experimental Methodsmentioning

confidence: 99%

Characteristics of thermophysical parameters in the Wugongshan area of South China and their insights for geothermal genesis

Zhang

et al. 2023

Front. Environ. Sci.

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The Wugongshan area is rich in medium–low temperature convective geothermal resources, among which there are more than 10 geothermal fields in Wentang, Wanlongshan, Wenjia, Hongjiang, etc. There are few basic geothermal geological studies in the geothermal fields and their peripheral areas; thus far, no systematic research work into the thermophysical parameters has been carried out. In this paper, 85 rock samples were collected from the surface and boreholes covering the strata and magmatic rocks in the study area. The results show that the average radioheat generation rate, the average thermal conductivity, and the average specific heat are 0.24–5.49 (μW/m3), 1.995–4.390 (W/mK), and 1.318–4.829 (MJ/m3K), respectively. The average thermal diffusivity ranges from 1.115 to 1.611 × 10-6 m2/s. The highest radioheat generation rate is Jurassic granite, and the lowest is quartz vein. The largest thermal conductivity and specific heat is the siliceous quartzite, and the smallest is the quartz vein. The highest thermal diffusivity is Cambrian metamorphic mica schist, and the lowest is siliceous quartzite. The radioactive heat generation rate, thermal conductivity, specific heat, and thermal diffusivity are closely related to the chemical composition, mineral composition, rock fabric, porosity, water content, and temperature and pressure conditions of rocks in the whole area. There is a linear relationship between thermal conductivity (K) and thermal diffusivity (κ), and the correlation equation is K = −0.3144k + 3.2172. Combined with the characteristics of thermophysical parameters, the genetic theory of deep crust heat generation + structural heat accumulation + siliceous quartzite heat conduction + granite heat preservation is preliminarily proposed.

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Section: Sample Collection and Experimental Methodsmentioning

confidence: 99%

Characteristics of thermophysical parameters in the Wugongshan area of South China and their insights for geothermal genesis

Zhang

et al. 2023

Front. Environ. Sci.

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“…Besides the classic bulk analysis, the TPS method has recently been applied for investigating the variation of thermal conductivity as a function of the probing depth in inhomogeneous materials [ 35 ]. As a matter of fact, in the TPS method, the thermal penetration depth can be determined as a function of the measurement time by means of Equation ( 2 ):

where d

represents the experimental probing depth.…”

Section: Thermo-mechanical Analysesmentioning

confidence: 99%

Effect of PCM on the Hydration Process of Cement-Based Mixtures: A Novel Thermo-Mechanical Investigation

et al. 2018

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The use of Phase Change Material (PCM) for improving building indoor thermal comfort and energy saving has been largely investigated in the literature in recent years, thus confirming PCM’s capability to reduce indoor thermal fluctuation in both summer and winter conditions, according to their melting temperature and operation boundaries. Further to that, the present paper aims at investigating an innovative use of PCM for absorbing heat released by cement during its curing process, which typically contributes to micro-cracking of massive concrete elements, therefore compromising their mechanical performance during their service life. The experiments carried out in this work showed how PCM, even in small quantities (i.e., up to 1% in weight of cement) plays a non-negligible benefit in reducing differential thermal increases between core and surface and therefore mechanical stresses originating from differential thermal expansion, as demonstrated by thermal monitoring of cement-based cubes. Both PCM types analyzed in the study (with melting temperatures at 18 and 25 ∘C) were properly dispersed in the mix and were shown to be able to reduce the internal temperature of the cement paste by several degrees, i.e., around 5 ∘C. Additionally, such small amount of PCM produced a reduction of the final density of the composite and an increase of the characteristic compressive strength with respect to the plain recipe.

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“…The thermophysical properties of a substance are observed to characterize its heat transport and heat carrying capacity, which is an important basis for material selection and thermal process analysis. The transient planar source (TPS) method is one of the most important general methods for testing the thermal conductivity and thermal diffusion coefficients, which are widely used in testing of the thermophysical properties of various materials such as, fluids [ 1 , 2 , 3 ], solids [ 4 , 5 , 6 ], powders [ 7 , 8 ], and thin films [ 9 , 10 ]. TPS provides a double helix probe (for heating and temperature sensing) and an idealized heat transfer analysis model.…”

Section: Introductionmentioning

confidence: 99%

Improved Bayesian Optimization Framework for Inverse Thermal Conductivity Based on Transient Plane Source Method

Liu

Lyu

et al. 2023

Entropy

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In order to reduce the errors caused by the idealization of the conventional analytical model in the transient planar source (TPS) method, a finite element model that more closely represents the actual heat transfer process was constructed. The average error of the established model was controlled at below 1%, which was a significantly better result than for the analytical model, which had an average error of about 5%. Based on probabilistic optimization and heuristic optimization algorithms, an optimization model of the inverse heat transfer problem with partial thermal conductivity differential equation constraints was constructed. A Bayesian optimization algorithm with an adaptive initial population (BOAAIP) was proposed by analyzing the influencing factors of the Bayesian optimization algorithm upon inversion. The improved Bayesian optimization algorithm is not affected by the range and individuals of the initial population, and thus has better adaptability and stability. To further verify its superiority, the Bayesian optimization algorithm was compared with the genetic algorithm. The results show that the inversion accuracy of the two algorithms is around 3% when the thermal conductivity of the material is below 100 Wm−1K−1, and the calculation speed of the improved Bayesian optimization algorithm is three to four times faster than that of the genetic algorithm.

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Thermal depth profiling of materials for defect detection using hot disk technique

Cited by 10 publications

References 13 publications

Characteristics of thermophysical parameters in the Wugongshan area of South China and their insights for geothermal genesis

Characteristics of thermophysical parameters in the Wugongshan area of South China and their insights for geothermal genesis

Effect of PCM on the Hydration Process of Cement-Based Mixtures: A Novel Thermo-Mechanical Investigation

Improved Bayesian Optimization Framework for Inverse Thermal Conductivity Based on Transient Plane Source Method

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