Thermal Physical Characteristics Research Articles

Eco-friendly green roof solutions: Investigating volcanic ash as a viable alternative to traditional substrates

This research investigates the potential of volcanic ash as a green roof material, focusing on its thermal conductivity, physical characteristics, and permeability. Laboratory tests were conducted to determine thermal conductivity under different moisture conditions using two measurement devices, TLS 100 and HFM 436/3/1 Lambda. The results revealed that thermal conductivity increases with higher moisture content, indicating improved heat conduction as the material becomes more saturated with water. Particle size distribution analysis demonstrated that the majority of volcanic ash particles fall within the range of sand and gravel, providing a porous and well-draining material. Sand-sized particles create interconnected voids, facilitating efficient water movement, while gravel-sized particles enhance structural stability and load-bearing capacity. The limited presence of silt-sized particles further validated the material's suitability for green roof applications. Permeability tests on loosely compacted volcanic ash revealed higher permeability at 0% compaction, aligning with intended green roof configurations. This high permeability ensures effective drainage, preventing water accumulation and promoting healthy vegetation growth. At 20% compaction, the material still effectively managed water under potential compaction forces, striking a balance between drainage and water retention. Visual examination of green roof samples demonstrated that volcanic ash substrates resisted weed growth due to the absence of fertilization. While the commercial substrate exhibited better vegetation development due to added nutrients, volcanic ash substrates supported vegetation survival throughout the summer period with an irrigation system, reducing maintenance and lifecycle costs. In conclusion, the research findings indicate that volcanic ash possesses desirable thermal properties, a suitable particle size distribution, and favorable permeability characteristics for green roof applications. Its potential as a sustainable and cost-effective alternative to commercial substrates is evident, offering resilient urban landscapes with reduced environmental impact. Further exploration and optimization could solidify volcanic ash as a valuable component in advancing green roof technologies, promoting sustainable urban development.

Selection and thermal physical characteristics analysis of in-situ condition preserved coring lunar rock simulant in extreme environment

With the increasing scarcity of Earth’s resources and the development of space science and technology, the exploration, development, and utilization of deep space-specific material resources (minerals, water ice, volatile compounds, etc.) are not only important to supplement the resources and reserves on Earth but also provide a material foundation for establishing extraterrestrial research bases. To achieve large depth in-situ condition-preserved coring (ICP-Coring) in the extreme lunar environment, first, lunar rock simulant was selected (SZU-1), which has a material composition, element distribution, and physical and mechanical properties that are approximately equivalent to those of lunar mare basalt. Second, the influence of the lunar-based in-situ environment on the phase, microstructure, and thermal physical properties (specific heat capacity, thermal conductivity, thermal diffusivity, and thermal expansion coefficient) of SZU-1 was explored and compared with the measured lunar rock data. It was found that in an air atmosphere, low temperature has a more pronounced effect on the relative content of olivine than other temperatures, while in a vacuum atmosphere, the relative contents of olivine and anorthite are significantly affected only at temperatures of approximately −20 and 200 °C. When the vacuum level is less than 100 Pa, the contribution of air conduction can be almost neglected, whereas it becomes dominant above this threshold. Additionally, as the testing temperature increases, the surface of SZU-1 exhibits increased microcracking, fracture opening, and unevenness, while the specific heat capacity, thermal conductivity, and thermal expansion coefficient show nonlinear increases. Conversely, the thermal diffusivity exhibits a nonlinear decreasing trend. The relationship between thermal conductivity, thermal diffusivity, and temperature can be effectively described by an exponential function (R2>0.98). The research results are consistent with previous studies on real lunar rocks. These research findings are expected to be applied in the development of the test and analysis systems of ICP-Coring in a lunar environment and the exploration of the mechanism of machine-rock interaction in the in-situ drilling and coring process.

Synthesis and thermophysical properties of (AlxY1-x)TaO4 ceramics as thermal barrier coating materials

YTaO4 is considered a promising thermal barrier material, and Al2O3-doped YTaO4 can significantly enhance the thermophysical properties of this material. In this paper, in order to study in detail the thermophysical properties of Al2O3 doped YTaO4, bulk (AlxY1-x)TaO4 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) ceramics were firstly prepared by hot-pressure sintering, the phase composition, microstructure and the thermal physical characteristics of the specimens were tested. The result shows that, the thermal conductivity of (AlxY1-x)TaO4 ceramics is substantially diminished due to the phonon-point defect scattering mechanism, with a minimal value of about 1.73 W m−1 K−1 at 1000 °C, which is about 31% lower than that of YSZ. The ultimate thermal conductivity of the (AlxY1-x)TaO4 ceramics is predicted by different theoretical models, and it is discovered that the thermal conductivity of the materials could be further reduced by Al2O3 doping. Moreover, the thermal expansion coefficient of (AlxY1-x)TaO4 ceramics (9.8–11.1×10−6 K−1, 1200 °C) is remarkably similar to that of YSZ. The superior thermophysical properties of (AlxY1-x)TaO4 ceramics make them a promising candidate for thermal barrier coatings.

Thermal Transport and Physical Characteristics of Silver-Reinforced Biodegradable Nanolubricant

In this investigation, the thermal transport behavior of biodegradable lubricant reinforced with silver nanostructures (AgNs) at various filler fractions of 0.01, 0.05, 0.10, and 0.20 weight percent was evaluated over a temperature scan analysis, ranging from room temperature up to 60 °C. The experimental results revealed significant gradual enhancements in thermal conductivity as AgNs concentration and evaluating temperatures were increased. These improvements showed the important role of nanostructures’ interaction within the biodegradable lubricant. The thermal conductivity performance improved for nanolubricants ranging from 6.5% at 30 °C and 0.20 wt.% AgNs content up to a maximum 32.2%, which was obtained at 60 °C with 0.20 wt.% AgNs concentration. On the other hand, the thermal stability of reinforced lubricants was assessed through thermogravimetric kinetics analyses. The predictive curves resulting from the analyses indicated that there is an enhancement in both the onset temperature for decomposition and the percentage conversion under isothermal conditions for lubricants reinforced with AgNs. Specifically, the results show that the required temperature to achieve a 5% conversion is 100 °C higher than that calculated for bare lubricant. Moreover, the predictive analyses indicate that there is a delay in the decomposition time at isothermal conditions.

Determining the thermal-physical characteristics of a coke foam layer in the fire protection of cable articles with foaming coating

An issue related to using cable products for building structures is to ensure their stability and durability when operating within wide limits. Therefore, the object of research was a change in the properties of the polymer sheath of the cable during the formation of a swollen coating layer under the influence of high temperature. It is proved that in the process of thermal action on the flame retardant coating, the process of thermal insulation of the cable involves the formation of particulate products on the surface of the sample. Under the action of the burner flame, a temperature was reached on the surface of the sample, which led to a swelling of the coating of more than 16 mm. The measured temperature on the inverse surface of the sample was no more than 160 °C, which indicates the formation of a barrier for temperature. In this regard, a calculation and experimental method for determining thermal conductivity when using a flame retardant as a coating has been developed, which makes it possible to estimate the coefficients of temperature conductivity and thermal conductivity under high-temperature action. According to the experimental data and established dependences, the coefficients of temperature conductivity and thermal conductivity of wood were calculated, which are 214.4·10–6 m2/s and 0.62 W/(m∙K), respectively, due to the formation of a heat-insulating swollen layer. The maximum possible temperature penetration through the thickness of the coating was assessed. A temperature was created on the surface of the sample, which significantly exceeds the ignition temperature of the polymer sheath of the cable, and, on a non-heated surface, does not exceed 160 °C. Thus, there is reason to argue about the possibility of directed adjustment of the fire protection processes of an electrical cable by using coatings capable of forming a protective layer on the surface of the material, which inhibits the rate of heat transfer.

Low-temperature high-strength lightweight refractory composites: Pore structures and insulating properties

Functional refractory remains critical due to its intrinsic properties such as: saving space, lightweight and excellent thermal stability to achieve the trade-off between insulating and overall performances. The present study deals with the production of low carbon footprint and lightweight refractory matrices, with controllable pores structures, thermally stable and having low thermal conductivities. The lightweight refractory products were obtained through the direct foaming of geopolymer pastes and sintered from 900 to 1200 °C. The mechanism of pores formation, pores structures and the effect of both sintering temperature and foaming agent ratio on the thermal insulation, physical and microstructural characteristics were evaluated. The results showed that the produced matrices could be described as low thermal conductors, with thermal conductivity values between 0.49 and 0.18 W/mK. The 3D internal pore structures under laser microscopy observations confirms the mechanism of pore enlargement when high concentration of the foaming agent was added. Furthermore, the decomposition of kyanite particles within the matrices, at high temperature, favoured the extend reduction in porosity and the limitation of the liquid phase, by ensuring the formation of macro-porosities sized between 360 μm and 2 mm. The formation of the refractory crystalline phases namely: cordierite, mullite, enstatite, leucite, as well as, kalsilite, acting as filler, ensure thermal stability of the matrices. The produced materials provide an energy-saving, lightweight ceramic foams with high-strength and low thermal conductivities, potential candidates for refractory applications.

The Thermal Manifestation Monitoring Program at Muara Labuh Case Studies

The thermal manifestations at the Muara Labuh field are monitored regularly to see their behaviors in response to the field production. The monitoring results are then used to identify and mitigate any potential hazards associated with the thermal area changes. This paper presents the monitoring results on the main thermal features Idung Mancung (IM) fumaroles complex, located in the vicinity of the steam cap production zone in the Northeast (NE) Sector of the field. Due to its proximity to the main production area, this thermal complex is considered to be susceptible to any reservoir changes. The thermal manifestations characteristics monitored are areal extent, numbers of the thermal funnels, the activities, physical and chemical characteristics, and geophysical signatures. Baseline data were taken from previous remote sensing studies, geology maps, and thermal manifestation geochemistry surveys prior to production periods. Remote sensing studies using true color composite (TCC) and NDVI suggest that the IM fumarole area covers the wider area prior to stage-1 project development in 2017. After production, periodic aerial photo analysis suggests no changes in IM fumarole thermal area growth. The fact is supported by the periodic Thermal Infra-Red Image (TIR), which shows no sign of thermal anomaly still contained inside the IM fumarole baseline area. IM fumarole field checks show that lack of thermal area changes and no sign that the manifestations have become more aggressive. Temperature and flow rate observation on several manifestation funnels indicates that rainfall rate variation affects the manifestation activities and temperature. As for the fumarole gas chemistry, the IM main fumarole shows a decreasing trend in NCG and CO2 contents from 2016 to 2021 and increasing in H2S, which indicates the return of degassing fluid. After one year of field operation, the microgravity and leveling survey in the IM fumarole area show slight changes from -0.1 to -0.14 mGal. The changes correspond with the area subsidence rate of -10 to -15 mm/yr. These changes are still considered low compared to other operating geothermal fields and did not directly affect the thermal manifestation activity.

Simulation of nomograms showing the heating of steel structures with flame retardant coatings of different thicknesses (in the water)

Introduction. High temperatures cause deformation of steel structures which also lose stability and the bearing capacity, resulting in the collapse of structures with the subsequent collapse of the building. It is understood that intumescent paints are often used to increase the fire-resistance limits of steel structures up to R 90 and R 120. However the fire protection effectiveness of intumescent paints has not been sufficiently studied for the case of the long-term operation, and the application of this type of fire protection treatment of bearing steel structures requires justification. To ensure the building stability, coupled with the required fire resistance limit of structures, one should study the engineering factors affecting the fire resistance of steel structures that have intumescent paint coatings.Purpose of the research work. Development of approaches to simulation of nomograms demonstrating the heating of steel structures with flame retardant coatings of different thicknesses. The research work solved the following tasks:block diagrams of the research undertaking were developed to find the fundamental relationships between the dynamics of change in the structure of fire protection materials under thermal effects and the fire resistance limit of a building structure based on the choice of the functional criterion;mathematical models demonstrating dependence between the thickness of the dry layer of fire-retardant material were developed; the required fire resistance limit and thermo-physical characteristics of fire-resistant materials based on the experimental studies of the properties and effectiveness of fire-resistant materials were identified;nomograms showing dependences between the thickness of the dry layer of flame retardant materials and the flame retardant efficiency of flame retardants were made.Research methods. Hot Disk TPS 1500 thermal constant analyzer was used to analyze the thermo-physical characteristics of flame retardant materials. Thermal analysis was used to study the properties of flame retardants, as well as physical and chemical transformations occurring inside them under the programmed exposure to temperature effects and with the use of specialized thermal analysis equipment. The study of the fire protection efficiency for steel structures was conducted in accordance with GOST R (Russian State Standard) 53295–2009 “Fire protection means for steel structures. General requirements. The method of fire protection efficiency determination”.Results and their discussion. As a result of the research, an approach to prediction of the fire resistance of building structures was developed in the form of a research flowchart, used to choose the functional criteria. Experimental studies were conducted to identify mathematical dependences between the fire resistance and the indicators, which serve as functional criteria. In particular, when assessing the fire resistance of steel structures, a prediction is made on the basis of thermos-physical indicators. The authors were first to propose the introduction of the function of fire protection materials into the standard pattern of fire resistance analysis in the course of solving static and thermo-physical problems. The obtained data were used to make equations of dependence between the thickness of a dry layer of a fire-retardant material, the required fire-resistance limit of a structure, and the nomogram showing the heating of protected steel structures with fire-retardant coatings of various thicknesses.Conclusions. The results of the studies allowed identifying fundamental relationships between the dynamics of change in the structure of fire-retardant materials under the thermal effect and the fire resistance limit of a building structure on the basis of the choice of a functional criterion. Experimental studies of the properties and effectiveness of fire-resistant materials were conducted to develop a mathematical model showing dependence between the thickness of the dry layer of fire-resistant materials, the required fire-resistance limit and thermal-physical characteristics of fire-resistant materials.

Studying the thermal characteristics and effectiveness of structural fire proofing made of PROSASK Firepanel cement boards by means of reproducing the high-temperature effect

Introduction.The application of PROZASK fire-retardant panels demonstrates an option for and the expediency of a comprehensive study of fire proofing characteristics.Goals and objectives.The mission of this research project is to (1) obtain the results of experimental studies of fireproofing panels, containing the cement binder, (2) determine their fire proofing efficiency, using the radiant heating test bench that reproduces pre-set modes of high-temperature exposure, and (2) analyze the testing results using the method of mathematical modelling of temperature fields inside fireproof structures.Methods.Standardized laboratory techniques were used to clarify the thermal-physical characteristics of boards at relatively low temperatures. Their fire proofing efficiency was evaluated in the course of additional testing of specimens using the radiant heating test bench. A reliable and relatively uncomplicated method and programme for calculating unsteady temperature fields in fireproof structures were used to conduct the thermal analysis and generalization of experimental results. The authors summarized the results of standardized tests, conducted in a fire furnace, to determine the flame-retardant efficiency of PROZASK Firepanel boards and the fire-resistance of the full-size structures they protect.Results.Values of specific heat capacity and the thermal conductivity coefficient of boards, tested using laboratory benches at relatively low temperatures, were verified. The results of thermocouple measurements, taken during the testing of specimens with the help of the radiant heating bench in standard and hydrocarbon temperature modes, were obtained. The processing of these results, using thermal engineering analysis, allowed determining the values of the thermal conductivity coefficient in the range of operating temperatures. The influence of moisture, contained in the boards, on their fire protection efficiency was evaluated. Comparison between the results of calculations and tests, conducted in the fire furnaces, showed the practical usability of the obtained characteristics of boards and the thermo-engineering analysis used to (1) clarify the fire-proofing efficiency and the design developed using PROZASK Firepanels and (2) evaluate the fire-resistance of the constructions they protect.Conclusions.The presented integrated studies generated a considerable amount of important information, required to prognosticate the fire proofing properties and the fire-resistance of constructions that contain PROZASK Firepanels. The role of additional testing of specimens using a radiant heating test bench and the effectiveness of thermal-engineering calculations as a tool for assessing the parameters of fire proofing and the fire resistance of structures are demonstrated.

Development and Properties of Functional Ceramic-based Photocatalytic Materials

With the rapid development of energy, information, environmental protection and biological science and technology, the material with a long history-ceramics, has also obtained a new research progress, namely, the development of functional ceramics. Functional ceramics play a key role in related scientific research and engineering project applications, with their unique thermal, electric, magnetic, acoustic and optical physical characteristics, chemical, biological and appropriate mechanics characteristics. Moreover, because the photocatalytic technology has the characteristics of mild reaction conditions, convenient operation and no secondary pollution, it is considered as the most promising environmental governance technology in the 21st century, that is, it can effectively solve the problems of fossil energy depletion and environmental pollution. In addition, photocatalytic technology also has the characteristics of low energy consumption, and has also become a necessary technology to develop new energy sources. If functional ceramics and photocatalytic technology are combined together, it will solve many problems in industrial production and life. A variety of materials with photocatalytic characteristics in functional ceramics have been developed. This paper mainly expounds the performance research and its development and application of Ti-based functional ceramic photocatalytic materials, multiple material composite ceramic photocatalytic materials and tungsten-based activated carbon-based ceramic photocatalytic materials.

Studying the Thermophysical Characteristics of the Muscle Mass of the Black Soldier Fly Larvaes (Hermetia Illucens) as a Drying Object

Introduction. The main component of the compound feedstuff is fish meal, which has unstable quality and high price. Fish and meat-and-bone meals are replaced with protein concentrates and higher quality larvae proteins. The source of feed protein is the biomass of the black soldier flies (Hermetia illucens), which have a rich amino acid composition and also process food waste. The aim of the work is to study the thermal-physical characteristics of the muscle mass of the black soldier fly larvaes (Hermetia illucens). Материалы и методы. The study focused on the muscle mass of black soldier fly larvaes (Hermetia illucens). The subject of the study is thermal-physical regularities during the drying process. The studies were conducted on the basis of Don State Technical University. The article describes determination of thermal-physical characteristics such as specific heat, thermal conductivity, moisture of the raw material, and oiliness. Results. Heat conductivity coefficient of water 0.555 W/(m∙K) for food and feed products from 0.25 to 0.40 W/(m∙K) black Soldier Fly larvae have a heat conductivity equal to 0.144 W/(m∙K), which is lower than conventional feedstuff components. The humidity of the examined raw material is 45% or higher while the heat conductivity remains linear and practically does not increase. Discussion and Conclusion. The results obtained during the work can be used for parameter determination and design of various types of dryers, and for mathematical description of the dynamics and kinetics of drying.

Reducing the level of interference at thermal non-destructive testing considering the specific thermal physical and morphological characteristics of the object

The Paton Welding Journal, 2022, №12. International Scientific-Technical and Production Journal «The Paton Welding Journal» «The Paton Welding Journal» has been published monthly since 2000 in English, ISSN 0957-798X. «The Paton Welding Journal» is a cover-to-cover English translation of the «Avtomaticheskaya Svarka» (Automatic Welding) journal. The «Avtomaticheskaya Svarka» journal has been published monthly since 1948 in Russian, ISSN 005-111X.

A Field Study of Coal Fire Areas Re-Burning Behavior Assessment and Related Carbon Emissions

The re-burning of coal seams still occurs in coal fire areas after firefighting projects. A large amount of spontaneous combustion gas products is released from the surface fissure, which can cause air pollution and even threaten the production of surrounding mining areas. However, the distribution characteristics of fissure channels in the re-burning coal fire areas are local and scattered. Therefore, we developed a system for the in situ monitoring of spontaneous combustion gas emissions from fissure channels to conduct field investigations on the re-burning behavior of coal seams to explore the degree of re-burning in the coal fire area. The results showed that re-burning of the coal fire area induced fissure channels with different shapes. The CO2 concentrations are always higher than the CO concentrations among the spontaneous combustion gas products discharged from the fissure channels. The degree of re-burning of coal seams at different study locations was comprehensively determined using simplified MCE and CO2/CO ratios. The comprehensive factor α was obtained using the generalized principal component analysis (GPCA) by taking into account spontaneous combustion gas, meteorological factors, and the thermal physical characteristics of fissures. A carbon emission model for local fissure channels in the coal fire area was established, and the daily average carbon emissions at the study location were 2.56 t. Therefore, this provides essential theoretical support for taking corresponding fire extinguishing measures according to the degree of re-burning of the coal fire area.

Effect of Coal Dust Content on the Low-temperature Oxidation of Silo Coal.

Coal’s low-temperature oxidation (LTO) poses a significant threat to the safety of storing coal in silos. This study investigates the impact of coal dust content on the LTO characteristics of silo coal samples. The results indicate that the larger the coal dust content the higher the oxygen (O2) consumption rate and carbon monoxide (CO) generation rate and the stronger the LTO capacity. To clear the mechanism of the impact, the thermal physical characteristics were studied and thermogravimetric and differential thermal analysis (TG-DTA) experiments were performed on various coal samples. The results show that, first, with the increase of coal dust content, the thermal conductivity of the silo coal samples initially increased and then decreased, whereas the thermal diffusion and heat capacity decreased and increased linearly, respectively. This indicates that the heat storage capacity of the silo coal sample is enhanced with the increase of the coal dust content. Second, the maximum oxygen absorption rate and differential thermal reduction value of the coal samples increased linearly with the decrease in their particle size; this result verifies that decreasing the particle size of silo coal can advance its LTO process. The study findings indicate that the risk of LTO and spontaneous combustion of silo coal can be effectively reduced by controlling the coal dust content (fine coal particles).

Characteristics of Precambrian basement intruded by Cretaceous geological intrusions in Monteregian Igneous Province and their impacts on regional thermal structure

With the progress of geothermal exploration in deep buried geological bodies, high radiogenic geological intrusions have become the hot spot in recent years. However, the assessment of the complex structure, lithology of geological intrusions by the geophysical methods has uncertainty, making it a challenging to accurately predict the thermal structure around the geological intrusions. In southern Québec, Canada, recent studies show that a relative high surface heat flux has been detected in the region enclosed by Montréal, Salaberry-de-Valleyfield and Saint-Jean-sur-Richelieu, around the southwest of the Monteregian Hills, which belong to the Early Cretaceous alkaline and carbonatite intrusions. It is not clear whether these Monteregian intrusions have impacts on the thermal anomaly of the Montréal, Salaberry-de-Valleyfield and Saint-Jean-sur-Richelieu region. The objective of this paper is to numerically investigate the thermal structure in the thermal anomaly region, considering the impact of different Monteregian intrusions. The simplified Monteregian intrusions are embedded into a three-dimensional geological model consisting of the sedimentary formations in the St. Lawrence Lowlands and the simulator Underworld2 is used for the thermal modelling. Simulation results show that the geological intrusions in this region have large impacts on the thermal structure at the local-scale, depending on the radiogenic heat production, thermal conductivity, emplacement depth and size. Temperature in the sedimentary formations may be lower or higher than that of the adjacent geological intrusions, highly depending on the thermal physical characteristics of these intrusions. Furthermore, the complex fault systems also strongly control the thermal distribution in different fault blocks, making the Potsdam Group sandstone located between the Grand-St-Esprit and Notre-Dame-du-Bon-Conseil faults as the potential geothermal reservoir. Cited as: Liu, H., Ban, S., Bédard, K., Giroux, B. Characteristics of Precambrian basement intruded by Cretaceous geological intrusions in Monteregian Igneous Province and their impacts on regional thermal structure. Advances in Geo-Energy Research, 2022, 6(3): 206-220. https://doi.org/10.46690/ager.2022.03.04

Evaluation of the depth of seasonal defrosting at change of thermal physical characteristics of bulk soils

Western Siberia is an important base for oil and gas production. The main number of deposits are arranged on bulk soils that violate the thermal regime of rocks and cause the development of a variety of engineering and geological processes and phenomena. The paper presents the results of determining the thermophysical characteristics of bulk soils selected at four fields in Western Siberia. Thermotechnical calculations were carried out to determine the depth of seasonal thawing and an assessment was made of the influence of the thermophysical properties of bulk soils on the change in thickness of the seasonally thawed layer.

Using near–surface temperature data to vicariously calibrate high-resolution thermal infrared imagery and estimate physical surface properties

Thermal response of the surface to solar insolation is a function of the topography and the thermal physical characteristics of the landscape, which include bulk density, heat capacity, thermal conductivity and surface albedo and emissivity. Thermal imaging is routinely used to constrain thermal physical properties by characterizing or modeling changes in the diurnal temperature profiles. Images need to be acquired throughout the diurnal cycle – typically this is done twice during a diurnal cycle, but we suggest multiple times. Comparison of images acquired over 24 hours requires that either the data be calibrated to surface temperature, or the response of the thermal camera is linear and stable over the image acquisition period. Depending on the type and age of the thermal instrument, imagery may be self-calibrated in radiance, corrected for atmospheric effects, and pixels converted to surface temperature. We used an experimental instrumentation where the calibration should be stable, but calibration coefficients are unknown. Cases may occur where one wishes to validate the camera's calibration. We present a method to validate and calibrate the instrument and characterize the thermal physical properties for areas of interest. Finally, in situ high-temporal-resolution oblique thermal imaging can be invaluable in preparation for conducting overflight missions. We present the following:•The use of oblique thermal high temporal resolution thermal imaging over diurnal or multiday periods for the characterization of landscapes has not been widespread but poses great potential.•A method of collecting and analyzing thermal data that can be used to either determine or validate thermal camera calibration coefficients.•An approach to characterize thermophysical properties of the landscape using oblique temporally high-resolution thermal imaging, combined with in situ ground measurements.

Range of change in Fourier numbers in thermal calculations of automobile roads in the cryolithic zone

An assessment of influence of thermal physical properties of dispersed rocks on the range of change in the values of Fourier numbers, used in thermal calculations of soil foundations of the automobile roads in the cryolithic zone, was carried out. The formulas applied in the calculation have considered the functional dependence of the thermal conductivity coefficient and the total heat capacity on the moisture (ice) content in the thawed and frozen state. A mixture of quartz sandstone with water in thawed state and ice in frozen state, with moisture (ice) content changing zero (dry quartz sandstone) to full moisture saturation, was used as an example. It was determined that the range and type of Fourier numbers for thawed and frozen dispersed rocks differs significantly, both quantitatively and qualitatively, depending on their moisture (ice) content. For thawed rocks, the Fourier number decreases as moisture content rises. For frozen rocks, it increases. It was demonstrated that in calculation of Fourier numbers for dispersed rocks it is important to properly apply the calculation models. In particular, if the model of material structure is not changed the reflect the respective contents of the binder and the filler components, above a particular concentration of the respective components, the calculation error in Fourier numbers can exceed 30%. An assessment of the possibility of averaging the thermal physical characteristics of the rocks to obtain the universal Fourier numbers was done. It was concluded that the use of universal Fourier numbers causes a significant error for both thawed and frozen rocks. Their use in thermal calculations over the yearly temperature changes is not expedient. It is correct to separate the thermal calculations into three components: calculation in the thawed state, calculation in the frozen state and calculation in the phase transition period of freezing and thawing, with corresponding calculation of Fourier numbers for every period and the aggregate state of the moisture in the dispersed rocks.

Dynamic analysis of heat extraction rate by supercritical carbon dioxide in fractured rock mass based on a thermal-hydraulic-mechanics coupled model

Heat production from geothermal reservoirs is a typical heat transfer process involving a cold working fluid contacting a hot rock formation. Compared to the thermal-physical characteristics of water, supercritical CO2 (scCO2) has a higher heat storage capacity over a wide temperature-pressure range and may be favored as a heat transfer fluid. Singularly characteristic of scCO2-based heat extraction is that the hydraulic-thermal properties of the scCO2 vary dramatically and dynamically with the spatial pressure gradient during unsteady-state flow along fracture. This highly nonlinear behavior presents a challenge in the accurate estimation of heat extraction efficiency in scCO2-based EGS. In this paper, a thermal–hydraulic-mechanical (THM) coupled model is developed by considering deformation of the fractured reservoir, non-Darcy flow and the varying thermal-physical properties of scCO2. The proposed model is validated by matching the modeling temperature distribution with published data. The results show that during continuous injection of scCO2, the fracture first widens and then narrows, ultimately reopening over the long term. The sequential fracture deformation behaviors are in response to the combined impacts of mechanical compression and thermally-induced deformation. By controlling the injection parameters of the scCO2, it is found that the heat extraction rate is positively correlated to its pore pressure or mass flow rate. The heat extraction rate can be significantly enhanced, when the inlet temperature of scCO2 is below its critical temperature. As a result, the heat increment recovered per unit mass of scCO2 decreases as the hot rock is gradually cooled. Meanwhile, the heat increment recovered per unit mass of scCO2 decreases by increasing the inlet temperature of scCO2 or its mass flow rate, but increases as the outlet pressure rises. Furthermore, multi-linear regression indicates that controlling the inlet temperature of the scCO2 can significantly improve the thermodynamic efficiency of heat extraction.

Determining patterns in thermoelastic interaction between a crack and a curvilinear inclusion located in a circular plate

A two-dimensional mathematical model of the thermoelastic state has been built for a circular plate containing a curvilinear inclusion and a crack, under the action of a uniformly distributed temperature across the entire piece-homogeneous plate. Using the apparatus of singular integral equations (SIEs), the problem was reduced to a system of two singular integral equations of the first and second kind on the contours of the crack and inclusion, respectively. Numerical solutions to the system of integral equations have been obtained for certain cases of the circular disk with an elliptical inclusion and a crack in the disk outside the inclusion, as well as within the inclusion. These solutions were applied to determine the stress intensity coefficients (SICs) at the tops of the crack. Stress intensity coefficients could later be used to determine the critical temperature values in the disk at which a crack begins to grow. Therefore, such a model reflects, to some extent, the destruction mechanism of the elements of those engineering structures with cracks that are operated in the thermal power industry and, therefore, is relevant. Graphic dependences of stress intensity coefficients on the shape of an inclusion have been built, as well as on its mechanical and thermal-physical characteristics, and a distance to the crack. This would make it possible to analyze the intensity of stresses in the neighborhood of the crack vertices, depending on geometric and mechanical factors. The study's specific results, given in the form of plots, could prove useful in the development of rational modes of operation of structural elements in the form of circular plates with an inclusion hosting a crack. The reported mathematical model builds on the earlier models of two-dimensional stationary problems of thermal conductivity and thermoelasticity for piece-homogeneous bodies with cracks.