Heat Flow Density Research Articles

Geothermal Sustainability or Heat Mining?

Heat mining” is, in fact a complete deceptive misnomer. When a mineral deposit (e.g. copper) is mined and the ore has been taken out, it will be gone forever. Not so with geothermal resources: The heat and the fluid are coming back! Namely, the heat and fluid extraction create heat sinks and hydraulic minima; around these, strong temperature and pressure gradients develop. Along the gradients, natural inflow of heat and fluid arises to replenish the deficits. The inflow from the surroundings can be strong: around borehole heat exchangers, heat flow densities of several W/m2 result, whereas terrestrial heat flow amounts only to about 50 – 100 mW/m2.
 The regeneration of geothermal resources after production, in other words, extraction of fluid and/or heat) is a process that runs over different timescales, depending on the kind and size of the utilization system, the production rate, and the resource characteristics. The resource renewal depends directly on the heat/fluid backflow rate. Heat, respectively fluid production from geothermal resources can be accomplished with different withdrawal rates. Although forced production is more attractive financially (with quick payback), it can nevertheless degrade the resource permanently. The longevity of the resource (and thus the sustainability of production) can be ensured by moderate production rates. The sustainable geothermal production level depends on the utilization technology as well as on the local geologic conditions. The stipulation of the sustainable production level requires specific clarifications, especially by numerical modelling, based on long-term production strategies. In general, resource regeneration proceeds asymptotically: strong at the beginning and slowing down subsequently, reaching the original conditions only after infinite time. However, regeneration to 95 % can be achieved much earlier, e.g. within the lifetime of the extraction/production system. In other words, geothermal resources may under certain circumstances may be considered as having potential regrowth, like biomass. Concerning the requirements for such sustainable production, it is convenient to consider four resource types and utilization schemes. These may be treated by numerical model simulations that consider heat extraction by geothermal heat pumps, hydrothermal aquifer, used by a doublet system for space heating, high enthalpy two-phase reservoir, tapped to generate electricity, and enhanced Geothermal Systems (EGS).

Energy loss analysis of the storage tank coil heating process in a dynamic thermal environment

Abstract With the increasing demand for crude oil reserves, storage tanks are being developed on a large scale, and heating energy consumption is gradually increasing. Hence, it is necessary to study energy utilization. The variable physical parameters of crude oil and dynamic thermal environment are considered to establish a coil heating theoretical model of a large crude oil storage tank. On this basis, according to the first and second laws of thermodynamics, the energy loss mechanism of the multiple links in the heating process is analysed. Moreover, the energy consumption evaluation index of the storage tank heating process is established, and the energy consumption mechanism accounting for the tank oil level, the coil heat flow density and the external environmental conditions for the heating process with different coil structures is proposed. The results reveal that the energy loss is affected by the external solar radiation and the dynamic change in the atmospheric temperature, which exhibits fluctuating and rising trends. The external heat loss discharged to the environment through heat dissipation is far lower than the internal heat loss of the tank. Among the different coil structures, an integral large vortex structure is formed for a serpentine coil, with the bottom coil acting as the power element. This large-scale vortex structure obtains energy from time-averaged flow through turbulent shear, which promotes the heat transfer process of natural convection. Additionally, each coil provides a certain buoyancy to the crude oil, and the heat absorption of the crude oil accelerates; thus, the crude oil has a high and stable effective energy utilization degree.

Study of the temperature regime effect on the process of cheeses vacuum drying

Vacuum drying is a promising way to cheese processing. The heating temperature is the most significant factor in vacuum drying. The purpose of this work was the selection of temperature regimes of vacuum cheese drying. Experiments on vacuum drying of cheeses were conducted at different temperatures and heat flow density. It has been established that the temperature decrease rises significantly the duration of drying process. Increasing the drying temperature up to 60 °C and more leads to a decrease in the temperature gradient across the thickness of the layer of dried cheese. The organoleptic characteristics of dry cheeses have been found to be most appreciated at vacuum drying temperatures of 50 and 60 °C. Based on the conducted research, the influence of temperature and heat flow density on the process of vacuum cheeses drying was analyzed. The recommended temperature for vacuum cheeses drying is (60 ± 3) °C, the recommended value of the heat flow density is (7.36 ± 0.3) kW/m2.

A numerical model to simulate the dynamic performance of Breathing Walls

A one-dimensional Finite Difference Model for Breathing Wall components under time dependent Dirichlet boundary conditions is presented. The algorithm undergoes a comprehensive validation against a dynamic analytical model, under either sinusoidal and generically periodic boundary conditions, adopting different airflow velocities and in relation to capacitive and resistive materials alternatively. It is found that the accurate prediction of the temperature profile inside the wall is influenced primarily by the timestep, whose optimal value can be identified through a preliminary frequency analysis of the boundary conditions. Moreover, for a better prediction of the surface heat flow density, and especially in insulating materials, refining the space grid below 1 mm is recommended, as well as the adoption of a 3-point numerical scheme. The numerical model is finally tested against experimental data on a porous concrete wall, showing that numerical errors may compare to other sources of uncertainties, regarding materials properties and boundary conditions.

Infinite-stage Nernst-Ettingshausen Cryocooler for Practical Applications

Recent developments in Nernst-Ettingshausen (NE) physical phenomena combined with advances in the performance of rare-earth permanent magnets make thermomagnetic (TM) cryocoolers well suited for practical applications. The device performance of a NE cryocooler depends on both the material and the geometric shape of the device. Despite continued progress in TM materials, the optimum shape is still based on a simplified infinite-stage model derived in 1963 by Harman [Adv. Energy Convers. 3(4), 667--676 (1963)]. Harman's model assumes several nonrealistic assumptions, such as temperature-independent material properties and constant current density. We relax such assumptions and derive a fully-temperature-dependent numerical model to accurately solve for the thermomagnetic features of a NE cooler with arbitrary geometry. We correct Harman's analytical function and compare its performance with the performance of devices of various shapes. The corrected shape has a higher coefficient of performance (COP) at higher temperature differentials, which indicates that when the material resistivity is a strong function of the temperature, the corrected infinite-stage device can provide better performance than Harman's geometry. Moreover, the corrected infinite-shape device can provide higher heat flow density under a similar optimum-COP condition. A case study based on a state-of-the-art TM material, $\mathrm{Bi}$-$\mathrm{Sb}$ alloy, is presented, and the critical parameters for designing an efficient thermomagnetic cooler are discussed in detail.

Параметр термічної ректифікації у біматеріалі з міжфазною тріщинуватістю

The phenomenon of thermal rectification in bi-material with a periodic system of gas-filled interfacial cracks has been studied. The change of thermal resistance and pressure of the crack filler under the action of tensile forces and uniform heat flow is taken into account. The gas pressure is determined from the Clapeyron-Mendeleev equation. The thermal resistance of the gas is directly proportional to the opening of the cracks and inversely proportional to the thermal conductivity of the gas. The thermo-elastic problem is reduced to nonlinear systems of singular integro-differential equations for an opening cracks and a temperature jump between the cracks faces. An analytical-numerical iterative procedure is proposed to solve the system of singular integro-differential equations. The parameter of thermal rectification is determined and its dependence on the applied on the thermal and mechanical loads, thermal conductivity and mass of the gas and the interfacial cracking factor of the bi-material is analyzed. The nonlinear dependence of the thermal rectification parameter on the heat flow density and the interfacial cracking factor is established. The thermal rectification is manifested to a greater extent for higher values of heat flow and lower thermal conductivity of gas.

Action of electrohydrodynamic flow on heat transfer at boiling

The influence of electric field intensity and interelectrode spacing on the main parameters of boiling process under the conditions of electrohydrodynamic flow has been studied. It has been established that the effect of field falls with the increase in the heat flow density. The optimal interelectrode spacing when the highest heat transfer can be achieved is revealed. The hydrodynamic picture of the two-phase flow in relation to the heat transfer rate is analyzed on the basis of visual observations and high-speed filming of the process. The calculation relationships that satisfactorily agree with the experimental results are obtained.

Heat flux density, mantle structure and oil and gas potential of the Yamal Peninsula (Arctic)

Research subject. The Yamal Peninsula is of interest due to the fact that the concentration of hydrocarbon deposits per unit area is more than 100 times higher than the “world average”, which is confirmed by the reserves of the largest oil and gas fields already discovered. At the same time, the knowledge of the deep horizons of the earth’s crust and mantle within the Yamal and adjacent areas is clearly insufficient in comparison with more southern regions.Methods. In this work, the method of seismic tomography was used, which makes it possible to identify anomalies in the velocities of seismic waves directly related to the heat flow density and geodynamic activity of the subsurface.Conclusons. Apparently, the Western Yamal positive thermal anomaly indicates a region of a high geodynamic activity permeable for deep fluid-gas streams. The location of Yamal on a slightly raised shoulder of this anomalous region has determined the high oil and gas potential of this peninsula. Other regions situated in the vicinity of the discovered thermal anomaly may present significant research interest.

Heat Flow in SW of Galicia And NW of Portugal. The Interpretation of a Seismic Anomaly

Four heat flow density values and five temperature-depth profiles were obtained in a heterogeneous region considering heat flow by conduction in the vertical direction, and heat sources in the crust due to radioactivity decay. The heat produced in the upper layers of the crust was obtained based on gamma-ray charts and published data of laboratory radioactivity measurements on samples taken from the region. Seismic data were used to obtain the thickness of the different layers of the upper and middle crust and the depth of the Moho discontinuity considered coincident with the crust/mantle boundary. The heat flow at the surface is obtained by adding the heat flow from the mantle with the heat generated by the radioactive sources in the crust. The method was applied to a region with one measured heat flow density value (Ourense) and four points without any heat flow density measurement. A heat flow value from the mantle was obtained with Ourense data. Special attention was given to a region (A) with a seismic anomaly near the surface. The anomaly was explained by mass deficit near the surface that gives rise to an abnormal density value and an increase in seismic wave velocity values. The decrease in density is due to the presence of water in the region forming an aquifer. Geothermometer values obtained from samples of water in the thermal springs of Tuy (Spain) and Monção (Portugal) were used as the water temperature at the bottom of the aquifer. Isostatic balance in the region was considered to obtain density values and the amount of water in the region. Thermal conductivity and radioactivity heat source values in the region were obtained considering the amount of water in the region. Values from 86 to 97 mW/m2 were obtained using the same value of heat flow from the mantle. This is due to different values of heat produced in the crust due to different thickness layer values or/and to different heat production values.

Deep geothermal energy in northern England: Insights from 3D finite difference temperature modelling

Many of the most widely used deep geothermal resource maps for the UK are produced by contouring around sparsely distributed and often unreliable data points. We thus present a MATLAB-based 3D finite difference temperature modelling methodology, which provides a means for producing more resolute and geologically realistic versions of these maps. Our case study area in northern England represents an area where both sedimentary basins and radiothermal granite bodies comprise potential geothermal resources. We divide our 3D model into geological units, which are then assigned separate thermal properties. Assuming conductive heat transfer and steady-state and fixed boundary conditions, we calculate 3D regional subsurface temperature. Due to our averaging technique for thermal properties, the resolution of our geological model is scarcely compromised with respect to similar finite element methods. One predicted ‘hot spot’ at 1 km depth in the central part of our case study area corresponds with the granitic North Pennine Batholith. Other shallow hot spots correspond with thermally insulating sedimentary rock units and geological structures that incorporate these units. Predictive heat flow density maps highlight areas with accelerated surface heat flow associated with shallow conductive basement rock and heat producing granite bodies. Our predicted subsurface temperatures show broad similarities with measured equilibrium borehole temperatures. Inaccuracies may relate to convective heat transfer involving fault systems, or input variables relating to the geological model. Our predictive subsurface temperature and heat flow density maps are more resolute and geologically realistic relative to pre-existing contoured maps. The method presented here represents a useful tool for understanding controls on subsurface temperature distribution and geothermal potential.

Performance analyses on a novel heat pump with a hybrid condenser combined with flat plate micro-channel heat pipe plus TEG and FPV evaporator

A novel heat pump with a hybrid condenser combined with flat plate micro-channel heat pipe (MCHP) plus thermoelectric generator (TEG) and Fresnel photovoltaic (FPV) evaporator is proposed and investigated in this paper. In the previous work, the TEG is inserted between the concentrated PV and absorber plate in the evaporator. Although the TEG can convert the heat stored on PV into electricity, it hinders the heat dissipation of PV, which affects the PV performance. However, if TEG is stalled in the condenser, it could improve the electrical performance and total performance of the system by transforming collected heat into electricity without affecting the heat dissipation of PV. In addition, the MCHP is used to collect heat in condenser to achieve a high heat flow density and high output of TEG. The results show that the addition of TEG in condenser could elevate the electrical and total performance of the system. The TEG not only increases electrical efficiency by 10.83% under 100 W/m2 irradiation, 292.15 K ambient temperature, and 303.15 K water temperature but also increases total exergy efficiency by 6.02% under 100 W/m2 solar irradiation, 286.15 K ambient temperature, and 297.15 K water temperature. The lifting effect is more significant under low solar irradiation. Moreover, the influence of solar irradiation, ambient temperature, and water temperature is also investigated and discussed.

Thermal Structure of the Northern Outer Albanides and Adjacent Adriatic Crustal Sector, and Implications for Geothermal Energy Systems

Using an analytical methodology taking into account heat flow density data, frictional heating, temperature variations due to the re-equilibrated conductive state after thrusting and geological constrains, we calculated surface heat flow, geotherms and isotherms along a balanced and restored regional geological cross-section. Our results highlight the impact of frictional heating produced by thrusts on the thermal structure of the study area, leading to a raising of the isotherms both in the inner Albanides to the E and in the Adriatic sector offshore. Minimum values of Qs in the surroundings of Tirana and the reconstructed 2D thermal structure suggest less favorable conditions for exploitation of geothermal energy, besides the direct use (Borehole Heat Exchanger-Geothermal Heat Pump systems). Nevertheless, the occurrence of the “Kruja geothermal zone”, partially overlapping this area and including hot spring manifestations, emphasize the structural control in driving hot fluids to the surface with respect to the regional thermal structure.

Structure, properties and oxidation resistance of prospective HfB<sub>2</sub>–SiC based ceramics

The paper focuses on obtaining a heterophase powdered and sintered ceramics based on hafnium diboride and silicon carbide by combined self-propagating high-temperature synthesis (SHS) and hot pressing (HP). The structure of the synthesized SHS powder consists of hafnium diboride grains and agglomerated polyhedral 2–6 μm silicon carbide grains. The powders obtained had an average particle size of ~10 μm with a maximum value of 30 μm. Phase compositions were identical for the ceramics sintered by hot pressing and the synthesized powder. The resulting compact featured by a high degree of structural and chemical uniformity, porosity of 3.8 %, hardness of 19.8±0.4 GPa, strength of 597±59 MPa, and fracture toughness of 8.8±0.4 MPa·m1/2. Plasma torch testing (PTT) was carried out to determine the oxidation resistance under the influence of a high-enthalpy gas flow. The phase composition and surface microstructure of the compact after testing were investigated. The HP compact demonstrated an outstanding resistance to the high-temperature gas flow at 2150 °С and heat flow density of 5.6 MW/m2 for 300 s. A dense protective oxide layer 30–40 μm thick was formed on the surface of HfB2–SiC ceramics during the plasma torch testing. The layer consisted of a scaffold formed by HfO2 oxide grains with a space between them filled with SiO2–B2O3 amorphous borosilicate glass. The HfB2–SiC SHS composite powder was hot pressed to produce experimental samples of model bushings for the combustion chamber of a low thrust liquid rocket engine designed for PTT in the environment close to actual operating conditions.

New heat flow data from the Veiholmen and Raudsand boreholes, middle Norway

New thermal data for Fennoscandia have been recently acquired in two boreholes, Veiholmen and Raudsand 5, which are located in the northern part of Møre and Romsdal county of middle Norway. The calculated values of the uncorrected average heat flow density are 55 and 56 mW/m2 within the Veiholmen and Raudsand 5 boreholes, respectively. But, the values of average heat flow density, corrected for topography and palaeoclimate, are the following: 71 mW/m2 within the Veiholmen borehole and 79 mW/m2 within the Raudsand 5 borehole. The estimated palaeoclimatic corrections are relatively high and reach almost 20 mW/m2, showing the significance of taking into account the influence of the last glacial periods on the present-day thermal regime within the uppermost crust of Fennoscandia for geothermal calculations. The heat flow density is slightly higher in the Raudsand 5 borehole than in the Veiholmen borehole, most likely, due to the presence of the massive gneisses within the Raudsand area, which are characterized by higher radiogenic heat production compared to the diorites on the Innveien Island, where the Veiholmen borehole is located. The latter demonstrates the importance of internal heat production within the crust in addition to the heat coming from the Earth’s interior.

Numerical Simulation of Friction and Heat Exchange in Viscous-Gravitational Fluid Flow in a Loop Thermosiphon

Numerical simulation of velocity and temperature fields with laminar liquid flow in a laboratory experimental loop thermosiphon (natural circulation loop) has been made. A vertical electrically heated pipe served as a lift section. Calculations were carried out for the case of heating the entire length of the pipe under conditions of constant heat flux density on the wall. The construction of the loop is considered, in which local pressure losses and friction losses of pressure in the descending pipe are negligibly small in comparison with friction losses of pressure in the ascending section. The object of the analysis is the laminar mode of flow. In this regime, in the flows originating exclusively under the action of thermogravitational forces, the skin-friction coefficient varies in the most sophisticated way along the flow. Using the results of calculation of velocity and temperature fields, the longitudinal changes of the skin-friction coefficients and of heat transfer coefficients are determined. As a whole, according to the results of 2D numerical simulation, the skin-friction coefficients depend in the main on the change of the velocity gradient on the wall along the flow as a result of practically continuous rearrangement of velocity profile along the entire heating zone. The form of the velocity profiles and the degree of their deformation depend in turn on the heat flow density on the wall and on the hydraulic diameter. It is shown that in a single-phase loop of natural circulation (i.e., under conditions where the liquid moves exclusively under the action of thermogravitational forces) the shear stresses on the wall change along the heating zone in a complex way, and the skin-friction coefficient cannot be described by the simple dependence of the form ξ = a/Reb for being used in one-dimensional calculations. In all of the calculated regimes, including the one with the least (of those considered) heat flux density on the wall, the Nusselt numbers exceeded the stabilized values under the conditions of forced flow with constant thermophysical properties. With increase in distance from the entrance into the zone of heating, the Nusselt numbers first decrease monotonically, attain minimum values, and then begin to increase.

Экспериментальное исследование двухфазного теплообмена в модели канала охлаждения головки цилиндра поршневого двигателя

Liquid cooling of cylinder and piston parts in highly boosted internal combustion engines is generally accompanied by local phase transition phenomena, such as surface nucleate boiling. The heat transfer coefficient of nucleate boiling is several times higher than that of single-phase convection. In order to efficiently exploit the thermal effect of nucleate boiling in cooling systems, simultaneously preventing emergency supercritical modes, a deeper understanding of boiling physics based on full-scale experiments is required. We conducted experimental investigation of heat transfer in a simulated cooling duct of a piston engine cylinder head, using a bespoke motor-free installation. We studied the effects of velocity, flow character and coolant type on the heat transfer, accounting for the presence of congestion regions. Over the course of the experiment, we simulated thermal conditions characteristic of different heat transfer types: single-phase convection, nucleate boiling, the onset of boiling crisis. We used the experimental data to plot the coolant heat flow density as a function of wall temperature for different measuring points situated inside the stream and the turbulent flow regions (congestion regions). We show that the mature nucleate boiling mode is the most favourable in terms of how uniform the temperature field within a part is. The experimental data obtained during the investigation may be used to verify mathematical simulations in the two-phase heat transfer theory, provided the data have been appropriately processed

Ascending Heat and Mass Flow in Continental Crust: on the Problem of Driving Forces of Tectogenesis

The geophysical and geochemical indicators of the ascending heat and mass flow in the continental crust—conductive heat flow through the surface of the crust and the isotopic composition of helium in freely circulating underground fluids—are considered. The tectonic ordering of the heat flow and the factors responsible for the dispersion in its density (q) are discussed. The sources and reservoirs of terrestrial helium are characterized; the stability of 3Не/4Не ratio in the geological section along the depth and in time is demonstrated; linear and areal variations in this ratio on different scales are revealed and their similarity with heat flow distribution is established. The correlations of helium isotopic composition in freely circulating underground fluids with the conductive heat flow density and helium composition in gases in the regions of recent volcanism as well as with strontium composition in young lavas indicate helium transport from the mantle to the crust by the magmatic melts.

Локалізація ексергетичних втрат в утилізаторі теплоти відхідних газів газоспоживальних теплових установок

The problem of increasing the thermodynamic efficiency of power plants can be solved only by using a complex approach using methods based on modern methods of exergy analysis in combination with methods of heat transfer theory, theory of linear systems, structural-variant methods, multi-level optimization methods, etc. The analysis of the possibility of applying the discrete-modular principle and the corresponding complex method for analyzing the efficiency of the exhaust gases heat-recovery exchanger of a cogeneration unit heat engine is performed in the paper. The aim of the work is to analyze the localization of exergy losses, their differentiation, and the establishment of the relative contribution of various types of losses to the general exergy losses in the exhaust gases heat-recovery exchanger of a cogeneration unit heat engine. The structural features of the heat-recovery exchanger and the exergy properties that reflect the essence of exergy methods: universality and additivity, made it possible to use the discrete-modular principle and a complex method based on exergy-dissipative functions for efficiency analysis. The advantage of this method is the ability to analyze the localization of exergy losses in separate modules of the heat-recovery exchanger and to differentiate the exergy losses associated with nonequilibrium heat transfer between the heat-transfer agents and the wall, heat conduction and the movement of heat-transfer agents. Using the chosen complex method, the analysis of the localization of exergy losses in the heat-recovery exchanger was carried out and the exergy-dissipative functions of each of the eight modules of the heat-recovery exchanger were calculated. Differentiation of exergy losses was carried out and the relative contribution of exergy losses associated with the processes of heat transfer from flue gases to the wall, from wall to water, in heat conduction processes, as well as exergy losses associated with the movement of heat-transfer agents, in the general exergy losses was analyzed. To determine the exergy losses due to nonequilibrium heat transfer between the heat-transfer agents and the motion of the heat-transfer agents, the differential exergy equations, the equations for the heat flow densities between the heat-transfer agents and the wall, the equation for the heat flow density due to heat conduction through the wall and the equations of motion are used. It has been established that the localization of maximum exergy losses in all modules of the heat-recovery exchanger is associated with losses due to heat transfer from flue gases to the wall.

Heat flow of Uzbekistan: geology and interpretation

The first determinations of the heat flow density in Uzbekistan, as well as in Central Asia as a whole, were carried out in the middle 1960s. In subsequent years, many researchers, primarily in connection with the search and exploration of oil and natural gas deposits, studied the geothermal field of the region. The data accumulated to date show a significant heterogeneity of the thermal field in both Uzbekistan and the adjacent territory of Central Asia. Rare wells were studied in the desert areas of Kyzyl Kum and Kara Kum. The heat flow in Uzbekistan varies over a wide range from 20–30 to approximately 100 mW/m2. Its high values are characteristic of intermountain depressions and blocks of the earth’s crust with a dense network of deep faults. The heat flow increases significantly in the southern and eastern parts of Uzbekistan, as well as in the neighbouring territories adjacent to the mountain structures of the Tien Shan and Pamir, characterized by high seismicity, tectonic and thermal activation. An updated map of the heat flow density of Uzbekistan was compiled and, separately for the Fergana Depression. They reflect a significant regional variability of the geothermal field. With the transition from the relatively flat territory of the Turanian Plate to mountain structures, the degree of differentiation by the heat flow increases significantly. This is typical of the entire orogenic Alpine-Himalayan Belt.

Experimental investigation of the effect of temperature on thermal conductivity of organic-rich shales

Experimental data on thermal conductivity of hydrocarbon reservoirs and surrounding formations at elevated temperatures are important for a variety of purposes: determining heat flow density; designing and optimizing thermal methods of enhanced oil recovery (EOR); basin and petroleum system modeling; exploitation of geothermal reservoirs; and design of radioactive waste disposal. However, there is an acute shortage of such data at present, particularly for unconventional reservoir rocks. We helped to fill this data gap by using a new, sophisticated technique to carry out thermal conductivity measurements on 28 oil shale samples from various unconventional formations in a temperature range of 30–300°С. The formations studied were Bazhenov and Abalak (West Siberia, Russia), Mendym, Domanic, Sargaev and Timan (Volga-Ural, Russia). Divided-bar and optical scanning methods were combined in the thermal conductivity measurements in order to account for thermal anisotropy and heterogeneity of the rocks and improve quality of the experimental data. Application of the optical scanning technique enabled us to select representative full-diameter or split-core samples from the continuous thermal core logging data and to choose an optimal location for drilling of core plugs from the core samples for measurement of thermal conductivity at elevated temperatures, with due account for anisotropy and heterogeneity inherent to oil shales. This approach enabled us to reveal and overcome systematic errors in previous measurements of oil shale samples using the divided-bar method and to develop an approach for the correction of measurement results. The measurements of thermal conductivity of our samples at elevated temperatures found a 5–27% decrease of rock thermal conductivity with temperature increase from 30 to 300°С. New methodology of the rock thermal conductivity determining at elevated temperatures is reported that includes a combination of two instruments: Thermal Conductivity and Thermal Diffusivity Scanner and DTC-300. It allowed to account for the contact resistance, non-ideal form of rock samples prepared for study (nonparallelism of rock samples surfaces), and changes in rock samples structure after heating.