Thermal Calculations Research Articles

Evaluation of influence of thermoplastic slurry flow conditions on heat transfer coefficient during beryllium ceramic formation

The article presents the results of calculation of the influence of thermoplastic slurry flow conditions on the total heat transfer coefficient when forming ceramic products. Methods of detailed description of casting processes and thermal calculations have been developed to ensure reliable correspondence of calculated data and experimental results implemented on the basis of calculational experiment. The modeling of physical processes occurring during the formation of products allows you to discover new opportunities for improving the quality of castings by allowing you to more closely track the change in the temperature-phase fields of the process and clearly present the solidification kinetics depending on the casting modes. The speed of heat removal from the casting during the solidification period determines the rate of movement of the slurry, along with the temperature field on which the width of the transition region depends. These factors have a direct influence on the formation of the structure of beryllium ceramics. The study of the heat exchange process in the formation of ceramic products depending on temperature, heat at phase transition is the main task, since they largely determine the technological and operational characteristics of beryllium ceramics. The design data allows to determine the optimal conditions of the ceramic casting process and to obtain a solidified product with a uniform structure at the outlet.

О ВЛИЯНИИ ТЕПЛОИНЕРЦИОННЫХ СВОЙСТВ ИЗОЛЯЦИОННЫХ МАТЕРИАЛОВ РЕЗЕРВУАРОВ СЖИЖЕННОГО ПРИРОДНОГО ГАЗА В РАСЧЕТЕ ТЕПЛОВЫХ ПОТЕРЬ

Negative factors in ensuring the safe operation of liquefied natural gas reservoirs are identified, which manifest themselves during liquefaction, unloading, receiving and regasification of the product. The role of heat losses in ensuring the safe operation of tanks is shown. Methods are analyzed in terms of considering possible variable thermal effects on the outer surface of a tank with liquefied natural gas. A method for thermal calculation of an isothermal tank is presented, which makes it possible to consider the thermal inertia of multilayer insulation when exposed to thermal radiation from a fire of variable intensity.

Magnetic Particle Imaging-Guided Thermal Simulations for Magnetic Particle Hyperthermia.

Magnetic particle hyperthermia (MPH) enables the direct heating of solid tumors with alternating magnetic fields (AMFs). One challenge with MPH is the unknown particle distribution in tissue after injection. Magnetic particle imaging (MPI) can measure the nanoparticle content and distribution in tissue after delivery. The objective of this study was to develop a clinically translatable protocol that incorporates MPI data into finite element calculations for simulating tissue temperatures during MPH. To verify the protocol, we conducted MPH experiments in tumor-bearing mouse cadavers. Five 8-10-week-old female BALB/c mice bearing subcutaneous 4T1 tumors were anesthetized and received intratumor injections of Synomag®-S90 nanoparticles. Immediately following injection, the mice were euthanized and imaged, and the tumors were heated with an AMF. We used the Mimics Innovation Suite to create a 3D mesh of the tumor from micro-computerized tomography data and spatial index MPI to generate a scaled heating function for the heat transfer calculations. The processed imaging data were incorporated into a finite element solver, COMSOL Multiphysics®. The upper and lower bounds of the simulated tumor temperatures for all five cadavers demonstrated agreement with the experimental temperature measurements, thus verifying the protocol. These results demonstrate the utility of MPI to guide predictive thermal calculations for MPH treatment planning.

Gas Composition Tracking in a Transient Pipeline Using the Method of Characteristics

For a gas pipeline with multiple gas sources, the significance of tracking the composition of natural gas is increasing with the implementation of X+1+X system for the natural gas industry in China. Mathematically, the tracking problem is usually described by a system of partial differential equations (PDEs). The continuity equation on gas composition has been developed to track natural gas composition according to the law of mass conservation. The algorithm resulting from the method of characteristics (MOC) is proposed to solve the system of PDEs. Compared to the original MOC, numerical solutions of the continuity equation on gas composition are obtained after the hydraulic calculation and thermal calculation. Moreover, different combinations of boundary conditions for the MOC are derived, which could expand the range of application of the MOC and be applicable to various operating conditions. The heating values of diverse gas sources have been determined following the methods documented in ISO 6976:2016. The case study of a gas pipeline in China verified the validity of the algorithm via the commercial simulation software Pipeline Studio for Gas (TGNET). The heating value and gas composition obtained by the algorithm can be used in the custody transfer metering of natural gas pipelines for Class B and C metering stations described in GB/T 18603−2014.

Novel Cast Ni‐Based Superalloys with Superb Weldability and Mechanical Properties Screened by a Multiperformance‐Oriented Criterion

Herein, innovative cast Ni‐based superalloys that not only withstand temperatures up to 800 °C but also offer superior weldability, robust tensile strength at both room and elevated temperatures, and a reduced density are introduced. The new Ni‐based superalloys are optimized via calculation of phase diagrams‐based high‐throughput thermal calculation and program‐controlled composition screening. A new multiperformance‐oriented criterion is devised, encompassing quantitative weldability indices, volume fraction of γ′, electron vacancy number, density, solidus temperature, and freezing range to optimize the alloy composition. Weldability indices, rooted in the solidification crack initiation mechanisms, prove equally applicable to both current interested alloys and commercial superalloys. The crack length of the optimized alloy after the constrained welding test is only 3.08% of the total weld length. It is unveiled that solidification cracking (SC) emerges as the pivotal factor governing the weldability of these alloys. The mechanism of SC for such superalloys is originated from the addition of Nb, Ti, Mo, and W, which results in the microsegregation of the composition and the precipitation of (Nb, Ti)‐rich constituents or M(Ta, Nb, Ti)C carbides in the liquid film of the central interdendritic region. This work hopefully helps to find promising candidates for the combustion chamber of aeroengines and other high‐temperature casts.

Improved Research on Two-Step Thermal Stress Calculation Method for Asphalt Mixture: Extended Creep Compliance Test.

The two-step thermal stress calculation method (TTSCM) is commonly used to predict the cracking temperature of asphalt mixture. The aim of this study is to improve TTSCM's mathematical model so as to enhance its prediction accuracy. First, this study evaluated the errors of predicted cracking temperatures of original TTSCM for AC-16 and AC-25 asphalt mixtures by thermal stress-restrained specimen test (TSRST). Then, an improved method called the extended creep compliance test (ECCT) was developed to modify the TTSCM. The test results show that the cracking predictions of the original TTSCM are not always accurate. Particularly for AC-16 asphalt mixture, the predicted cracking temperature is 2.9 °C (-10.6%) higher than the measured value by the TSRST. The ECCT method has been proven to be an effective way to enhance the prediction accuracy of the TTSCM. The predicted cracking temperatures modified by the ECCT method for both asphalt mixtures are relatively accurate, having an error within ±2%. The ECCT method changed the calculated thermal stress values at different temperatures of the TTSCM; however, they still conformed to a basic changing trend with respect to the initial temperature and cooling rate. Finally, a recommendation regarding the ECCT method was presented.

Ion velocity effect governs damage annealing process in defective KTaO3

Effects of electronic to nuclear energy losses (S e/S n) ratio on damage evolution in defective KTaO3 have been investigated by irradiating pre-damaged single crystal KTaO3 with intermediate energy O ions (6 MeV, 8 MeV and 12 MeV) at 300 K. By exploring these processes in pre-damaged KTaO3 containing a fractional disorder level of 0.35, the results demonstrate the occurrence of a precursory stage of damage production before the onset of damage annealing process in defective KTaO3 that decreases with O ion energy. The observed ionization-induced annealing process by ion channeling analysis has been further mirrored by high resolution transmission electron microscopy analysis. In addition, the reduction of disorder level is accompanied by the broadening of the disorder profiles to greater depth with increasing ion fluence, and enhanced migration is observed with decreasing O ion energy. Since S e (∼3.0 keV nm−1) is nearly constant for all 3 ion energies across the pre-damaged depth, the difference in behavior is due to the so-called ‘velocity effect’: the lower ion velocity below the Bragg peak yields a confined spread of the electron cascade and hence an increased energy deposition density. The inelastic thermal spike calculation has further confirmed the existence of a velocity effect, not previously reported in KTaO3 or very scarcely reported in other materials for which the existence of ionization-induced annealing has been reported. In other words, understanding of ionization-induced annealing has been advanced by pointing out that ion velocity effect governs the healing of pre-existing defects, which may have significant implication for the creation of new functionalities in KTaO3 through atomic-level control of microstructural modifications, but may not be limited to KTaO3.

Effects of Nanocomposite Derivatives of Ni-Fe, Ni-Co, Ni-Co-Fe Prussian Blue Analogues on the Thermal Decomposition Performance of Nitrocellulose.

The incorporation of nanomaterials generated from Prussian blue (PB) derivatives has emerged as a promising strategy to significantly improve the properties of energetic materials. In this study, we comprehensively investigated the influence of nanomaterials derived from PB on the thermal decomposition characteristics of energetic materials. To achieve this goal, we prepared nanomaterials using coprecipitation and heat treatment methods with PB derivatives as catalysts. Advanced techniques such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller (BET) analysis for specific surface area and pore size, and X-ray photoelectron spectroscopy were employed to thoroughly characterize these nanomaterials. Differential scanning calorimetry was used to assess the thermal behavior of nitrocellulose (NC), and the relevant kinetic parameters were determined through thermal decomposition kinetics calculations and analysis. This work revealed the influence of catalysts on the NC decomposition process and provided comprehensive insights into the effect of integrating nanomaterials derived from PB derivatives on the thermal decomposition performance of NC. The results of this work demonstrated the possibility of using nanomaterials generated from PB derivatives as effective catalysts to enhance the thermal decomposition characteristics of NC, offering interesting opportunities for their application in the field of high-energy materials.

Forward modeling of the Mg I 12.32 μm line from a 3D magnetohydrodynamic model of an enhanced network

Context. The Mg I 12 μm lines, 12.22 and 12.32 μm, represent a pair of emission lines, and their line cores originate around the temperature minimum region. These lines exhibit the highest ratio of Zeeman to Doppler broadening in the infrared solar spectrum, making them crucial for accurately investigating the solar magnetic field. Aims. We synthesized the Mg I 12.32 μm Stokes profiles from a 3D magnetohydrodynamic (MHD) model and studied the validity of different methods for extracting the magnetic field. The observational profiles at different spatial resolution were simulated, which are helpful for the design of future solar telescopes with large apertures. Methods. We used a 3D MHD simulation model for an enhanced network computed using the Bifrost code. We performed nonlocal thermal equilibrium calculations for Stokes profiles of the Mg I 12.32 μm line using the Rybicki–Hummer code. Results. From the simulation we determined the average formation height of the Mg I 12.32 μm line to be around 450 km. The various solar features have different formation heights, and the variance of formation height in magnetic concentration regions is about 160 km. The wavelength-integrated method is proven effective in calibrating the integrated Stokes profiles to obtain the longitudinal (Bl) and horizontal (BH) field components for weak magnetic fields; the Bl is below 300 G. Furthermore, the weak field approximation was found to be valid only for estimating magnetic fields with Bl below 150 G. The Stokes I profiles clearly show Zeeman triple splitting around the magnetic flux concentration with a grid resolution of 48 km. We determined that a resolution of 0.97″, equivalent to the diffraction limit of a telescope with a diameter of 3.2 m, was necessary to detect the Zeeman splitting for the simulated snapshot. Our results from this 3D MHD model are valuable for interpreting data from the Accurate Infrared Magnetic Field Measurements of the Sun (AIMS) telescope and designing future solar infrared telescopes.

Thermal conductivity of irregularly shaped nanoparticles from equilibrium molecular dynamics

The computation of thermal conductivity for finite nanoparticulate systems, particularly those of irregular shapes, poses significant challenges. The nonequilibrium molecular dynamics (NEMD) methods has been extensively utilized in numerous prior studies for the computation of thermal conductivity of nanoparticles. One of our recent works (Dong et al 2021 Phys. Rev. B 103 035417) proposed that equilibrium molecular dynamics (EMD) methods can be used for the simulation of thermal conductivity of finite-scale systems and demonstrated their equivalence to NEMD methods. In this study, we investigated the application of the (EMD) approach for the computation of thermal conductivity in zero-dimensional nanoparticles. In our initial step, we merged both methodologies to substantiate the equivalence in thermal conductivity calculation for cube and cylinder nanoparticles. After filtering the data, we confirmed the usefulness of EMD for evaluating the thermal conductivity of zero-dimensional materials. The NEMD method faces challenges in accurately predicting thermal conductivity in nanoparticle systems with a varying cross-sectional area along the transport direction, whereas EMD methods can be utilized to estimate thermal conductivity when the volume is known. In a subsequent study, we used the state-of-the-art machine learning potential to calculate the thermal conductivity of spherical nanoparticles and compared the results with those obtained using the classical Tersoff potential. Ultimately, we predicted the thermal conductivity of nanoparticles with various geometries in all directions. Our findings collectively demonstrate the simplicity and effectiveness of employing EMD methods for calculating thermal conductivity in nanoparticle systems, thereby opening up new avenues for investigating thermal transport properties in particle systems as well as nanopders.

A moment tensor potential for lattice thermal conductivity calculations of α and β phases of Ga2O3

Calculations of heat transport in crystalline materials have recently become mainstream, thanks to machine-learned interatomic potentials that allow for significant computational cost reductions while maintaining the accuracy of first-principles calculations. Moment tensor potentials (MTPs) are among the most efficient and accurate models in this regard. In this study, we demonstrate the application of MTP to the calculation of the lattice thermal conductivity of α and β-Ga2O3. Although MTP is commonly employed for lattice thermal conductivity calculations, the advantages of applying the active learning methodology for potential generation are often overlooked. Here, we emphasize its importance and illustrate how it enables the generation of a robust and accurate interatomic potential while maintaining a moderate-sized training dataset.

A new approach to crystal habit retrieval from far-infrared spectral radiance measurements

Abstract. To generate reliable climate predictions, global models need accurate estimates of all the energy fluxes contributing to the Earth's radiation budget (ERB). Clouds in general, and more specifically ice clouds, play a key role in the determination of the ERB as they may exert either a feedback or a forcing action, depending on their optical and microphysical properties and physical state (solid/liquid). To date, accurate statistics and climatologies of cloud parameters are not available. Specifically, the ice cloud composition in terms of ice crystal shape (or habit) is one of the parameters with the largest uncertainty. The Far-infrared Outgoing Radiation Understanding and Monitoring (FORUM) experiment, foreseen to be the ninth Earth Explorer mission of the European Space Agency, will measure, for the first time spectrally resolved from space, the entire upwelling spectrum emitted by the Earth from 100 to 1600 cm−1. The far-infrared portion of the Earth spectrum, especially from 200 to 600 cm−1, is very sensitive to cloud ice crystal shapes; thus, FORUM measurements could also represent an opportunity to study the ice cloud composition in terms of ice crystal habit mixtures. To investigate this possibility, we developed an accurate and advanced scheme allowing us to model ice cloud optical properties – also in cases of clouds composed of mixed ice crystal habits. This feature is in fact necessary because in situ measurements acquired over the years also point out that the shape of ice cloud crystals varies depending on the crystal size range. In our model, the resulting cloud optical properties are also determined by the input habit fractions. Thus, the retrieval of these fractions from spectral radiance measurements can be attempted. Using 375 different cloudy scenarios, we assess the performance of our retrieval scheme in the determination of crystal habit mixtures starting from FORUM-simulated measurements. The most relevant error components affecting the retrieved cloud parameters are not very large and are of random nature; thus, FORUM measurements will allow us to set up an accurate climatology of cloud parameters. To provide an example of the benefit that one could get from the habit mixture retrievals, we also show the improved accuracy of the thermal outgoing fluxes calculations compared to using assumed mixtures.

IMPROVING THE PLANTS EFFICIENCY OF THERMAL INCINERATION HOUSEHOLD WASTE BY RECOVERING WASTE HEAT

The work is devoted to research on the creation of recovery exchanger for waste heat exhaust gases of household waste incineration plants. The purpose of the work is to develop a technical solution for the heat recovery exchanger of waste incineration plants (WIP) and determine its thermal efficiency indicators. The main objectives of the study were to analysis of the modern experience of using the WIP and establish requirements for the creation of a exhaust gas heat recovery exchanger, develop a new technical solution for the heat recovery exchanger, and determine the change patterns in its main thermal indicators in different operating modes of the WIP. The known methods of thermal calculation of heat exchangers and the results of previous studies on the development and implementation of heat recovery equipment operating on dusty gases were used. The results of work on the creation of a new technical solution for an air-heating heat recovery exchanger with the ability to clean working surfaces from dust deposits are presented. The heat exchange surface of the heat recovery exchanger is composed of steel panels formed by tubes with membranes. The tubes applied have circular flow turbulizators on their internal surfaces. Turbulizators provide heat transfer intensification by 1.4 to 1.8 times with a moderate increase in aerodynamic resistance compared to other methods of heat transfer intensification. The regularities of changes in the main indicators of the heat recovery unit in different operating modes during the year in the practical range of changes in its input parameters were established. The research results show that, depending on the initial temperatures of gases and air, the excess air ratio in exhaust gases and the dust level of the working surface, the heat recovery exchanger provides heating capacity of 72-263 kW; cooling of exhaust gases to a temperature of 107-245 °C; heating of air to 96-220 °C. It was also established that the deposition of dust on the heat exchange surface of the heat recovery unit under the considered conditions leads to a decrease in the heating air temperature by 1.3-1.4 times and an increase in the final exhaust gas temperature by 1.1-1.2 times. At the same time, the heating capacity of the heat recovery exchanger is reduced by half. To increase heat recovery efficiency, it is necessary to periodically clean the working surfaces of the heat recovery unit with compressed air.

Thermal Stress Mechanism of Thermochemical Reactor of 5 kW Solar Simulator with Temperature Distribution as the Load Condition

In this paper, a solar thermochemical reactor is designed based on a 5 kW non-coaxial concentrating solar simulator, and a mathematical model is established for thermal calculations. The calculated temperature distribution is used as a load condition for thermal stress analyses. The model is used to study the influence of the solar simulator power, solar reactor inner wall material’s emissivity, working pressure, gas inlet velocity, and thermocouple opening diameter on the thermal stress of the solar reactor. The results show that thermal stress increases with the increase in solar simulator power and the emissivity of the inner wall material in the solar reactor. The inlet velocity and working pressure have little effect on the thermal stress of the reactor and cannot prevent damage to the reactor. In the case of maintaining the diameter of the thermocouple at the front end of the reactor, increasing the diameter of the thermocouple inside the reactor leads to an increase in thermal stress around the reactor. Meanwhile, using a finer thermocouple can reduce the thermal stress inside the reactor and extend its service life, which will provide a foundation for designing practical industrial applications in the future.

Computational Insight into the Physical Properties of Bulk MP (M = Li, Na, K) for Energy Applications.

In this study, we applied density functional theory to compute the electronic, optical, and thermal properties of MP (M = Li, Na, K). We find that the materials under consideration are stable, owing to the lack of negative frequencies in the phonon spectra. LiP exhibits an indirect band gap of 1.43 eV. NaP and KP have direct band gaps of 1.67 and 1.76 eV, respectively. The family of these composites shows strong absorption, observed by their very sharp absorption edges and confirmed by their direct transition from the valence to conduction band. They exhibit strong absorption below 4.0 eV in the optical spectra, which could serve in a solar cell device. The thermal calculations show high zT values of 0.74, 0.78, and 0.64 at 300 K for LiP, NaP, and KP, respectively. Thus, our results could be promising for electronic and thermal devices.

Near-, medium- and long-term impacts of climate change on the thermal energy consumption of buildings in Finland under RCP climate scenarios

The building sector is critical in climate change mitigation by reducing its energy consumption. At the same time, warming climate requires adaptation measures from buildings, making it necessary to study the future thermal energy demand of buildings. This paper studies the impact of climate change on the thermal energy demand of buildings in a heating dominated climate of Finland, under “representative concentration pathway” (RCP) climate scenarios in near- (2030), medium- (2050) and long-term (2080) horizon. Additionally, the impact of the thermal performance level of the buildings is investigated. The thermal energy demand calculation is based on overarching standards from the European “energy performance of buildings” directive. The weather scenarios present both typical and extreme weather years, applied through morphing and future weather data from the Finnish Meteorological Institute. The results show that annual thermal energy demand in Finland in 2080 can decrease up to 74.6kWh/m2. In addition, the decrease in heating demand will be higher than the increase in cooling demand. Cooling can become the dominant peak in long-term evaluations, especially in South Finland (Vantaa) with passive buildings under RCP8.5 climate scenario. Renovation is the most efficient action to decrease energy intensity, the earliest it is done the better.

Calibration, testing and application of the AquaCrop model for bean crop under irrigation regimes.

Crop growth simulation models relate the soil-water-plant-atmosphere components to estimate the development and yield of plants in different scenarios, enabling the identification of efficient irrigation strategies. The aim of this study was to calibrate crop coefficients for a common bean cultivar (IAPAR 57) and assess the AquaCrop model's efficacy in simulating crop growth under different irrigation regimes (T0 - non-irrigated, T1-fully irrigated, and T2-deficit irrigated) and sowing dates (S1-March 21, S2-April 24, and S3-August 23). Successful calibration was achieved for crop seasons with suitable temperatures to crop growth (S1 and S3). However, during periods with suboptimal temperatures (April 24 season), coupled with reduced irrigation supply (T0 and T2), the AquaCrop model did not appropriately account for the combined effects of thermal and water stresses. Despite adjustments to stress coefficients, this led to an overestimation of crop growth and yield. In long-term simulations, the model successfully replicated the variability of crop water availability over cropping seasons, reflecting the impact of precipitation variations. It recommended irrigation strategies for the study region (irrigate at depletion of 120 and 170% of readily available water for sowing on March 21 and August 24, respectively) to achieve high crop yield (> 2,769kgha-1) and water productivity (1,050 to 1,445kgm-3) with minimal application depths (< 150mm). While acknowledging the need for improvements in thermal stress calculations, the AquaCrop model demonstrates promising utility in studies and applications where water availability significantly influences crop production.

Evaluation of the thermal hazard and pyrolysis mechanism of 1-allyl-3-methylimidazole nitrate and 1-propyl-3-methylimidazole nitrate via thermal analysis and DFT calculation: Effect of structural characteristics

Imidazole ionic liquid, as a green solvent, is one of the most widely used ionic liquids. Understanding its thermal safety characteristics and mechanism is the essential basis for its safe application. In this paper, the thermal hazard characteristics of two ionic liquids with typical structural characteristics are systematically studied, which were 1-allyl-3-methylimidazole nitrate and 1-propyl-3-methylimidazole nitrate ionic liquids. The thermal decomposition peculiarities of two ionic liquids were systematically analyzed by thermogravimetric analyzer, differential scanning calorimetry and accelerating rate calorimeter techniques, and the risk of thermal runaway is also evaluated. In addition, the pyrolysis products and microscopic pyrolysis mechanism of ionic liquids were studied via thermogravimetry-Fourier transform infrared spectroscopy, thermogravimetric mass spectrometry and density functional theory calculation, and the essential mechanism of thermal hazard were determined. The influence of substituent structure on the thermal hazard characteristics of imidazole nitrate ionic liquid was preliminarily analyzed from macroscopic experiment and microscopic mechanism two aspects. This study provides a theoretical basis for the safe application, design and development of imidazole nitrate ionic liquids.

Theoretical study on the effective thermal conductivity of silica aerogels based on a cross-aligned and cubic pore model

Abstract Aerogel nanoporous materials possess high porosity, high specific surface area, and extremely low density due to their unique nanoscale network structure. Moreover, their effective thermal conductivity is very l1ow, making them a new type of lightweight and highly efficient nanoscale super-insulating material. However, predicting their effective thermal conductivity is challenging due to their uneven pore size distribution. To investigate the internal heat transfer mechanism of aerogel nanoporous materials, this study constructed cross-aligned and cubic pore model (CACPM) based on the actual pore arrangement of SiO2 aerogel. Based on the established cross-aligned and cubic pore model (CACPM), the effective thermal conductivity expression for aerogel was derived by simultaneously considering gas-phase heat conduction, solid-phase heat conduction, and radiative heat transfer. The derived expression was then compared with available experimental data and the Wei structure model. The results indicate that, according to the model established in this study for the derived thermal conductivity formula of silica aerogel, for powdery silica aerogel under the conditions of T=298K, a 2=0.85, D 1=90μm, ρ=128kg/m3, within the pressure range of 0-105Pa, the average deviation between the calculated values and experimental values is 10.51%. In the pressure range of 103-104Pa, the deviation between calculated values and experimental values is within 4%. Under these conditions, the model has certain reference value in engineering verification. This study also makes a certain contribution to the research of aerogel thermal conductivity heat transfer model and calculation formula.

New ways to improve the efficiency of railway transportation of viscous petroleum products

The paper proposes a new approach to solving the problem of increasing the economic efficiency of railway transportation of viscous petroleum fuels (fuel oils) at low air temperatures. The physical properties of fuel oils allow them to be obtained when poured into the tank of a tank wagon in a stratified state, when their density in the upper part of the tank is significantly less than in its lower part. This blocks the natural convection of hot fuel oil on the cold walls of the tank, and it cools only due to the molecular thermal conductivity which is very small. Upon cooling down, a relatively thin highly viscous layer forms on the inner walls of the tank of a tank wagon, which acts as a heat-insulating shell, and the bulk of it (more than 90%) retains high temperature and fluidity throughout the period of transportation. The thermal and hydrodynamic calculations were performed using modern computer technologies (the ANSYS 5.6 software package). The results obtained show that the need to heat up the fuel oil during unloading remains, but already requires significantly less time and heat energy. The proposed energy-saving technologies for the delivery of viscous petroleum products are especially relevant in Russia with its cold continental climate, long-haul transportation, and the current structure of the country’s wagon fleet. The value of the results obtained lies in the fact that the proposal can be implemented on tank wagons in circulation with minimal change to their design. The technology of operation of the drain equipment at unloading points will not change either.