Search

The paper presents an analysis of the heat transfer processes in electric arc plasma conditions between the powder material and the plasma jet in different convective states. The heat transfer processes in the plasma jet generated for coating deposition are considered based on varying the conditions for the jet–powder interaction. The formed coating deposited onto the substrate acts as an indicator of the heat transfer efficiency. The heat transfer between the plasma jet and the powder material is facilitated by the turbulent nature of the plasma jet. The presented calculation results demonstrate the influence of the plasma flow turbulence on the motion of the fine powder and heating of the generated jet at the outlet of the plasma torch. An analysis of the influence of plasma flow turbulence on the acceleration and heating of fine powder particles was carried out. The experimental results allowed for the determination of the effect of the plasma jet turbulence degree on the heat transfer processes between the plasma and fine powder: the technological efficiency of the device with varying parameters of the spraying process and the flow rates of the material supply and plasma-forming gas were presented. The values of the plasma-forming gas supply rate, the material supply rate, and the Reynolds number were obtained while the other process parameters were fixed. The research was carried out within the state assignment of the Ministry of Science and Higher Education of the Russian Federation (theme No. FSEG-2023-0012). [ABSTRACT FROM AUTHOR]

Russia has the largest volume of natural gas reserves in the world. Recoverable natural gas reserves amount to about 67 trillion cubic meters, according to the Ministry of Natural Resources and Environment of the Russian Federation for 2023. In recent years, the development of the Unified Gas Supply System has been growing rapidly. Since 2021 the Government of the Russian Federation has been actively introducing draft laws and regulations related to the scaling of the country's gasification. In June 2021 came out the Federal Law No. 184-FZ, which instructed the Government of the Russian Federation to adopt regulations aimed at implementation of provisions of free gasification of the country [1]. In September 2021 there was issued Decree No. 1547, [2] approving the new Rules for connecting gas-using equipment and capital construction facilities to gas distribution networks, which introduces the concept of pregasification. It is worth noting that new gas mains, compressor stations (CS) are put into operation, active reconstruction of the existing shops with exhausted gas compressor units (GCU) is carried out. One of the most urgent issues of the gas industry today is the efficient use of energy resources. Besides using the energy of flue gases from gas turbine drive of GPA, energy at gas throttling at gas distribution stations and other methods of energy saving, the significant role is played by the effective operation of air coolers of gas (ACG), the operation of which affects the reliable transportation of gas in the main gas pipeline (MG). The paper analyzes the methods of technical condition of gas air cooling devices of "Iceberg" type operated at the production site of the booster compressor station of "Gazprom Dobycha Nadym" LLC. The thermal efficiency of air coolers with all fans turned on and off was determined for the coldest and hottest months of the year. The electric energy savings of the frequency controlled drive (VFD) were calculated. [ABSTRACT FROM AUTHOR]

In regions characterized by continuous permafrost, hydrological modeling remains a complex activity, primarily due to constraints related to the prevailing climatic conditions and the specific behavior of the active layer. High-latitude regions receive less solar radiation; thus, most creeks are active only during summertime and stay frozen in the winter. To realistically simulate watersheds underlain by continuous permafrost, the heat transfer through the soil needs to be accounted for in the modeling process. In this study, a watershed located in a continuous permafrost zone in Russia is investigated. A model is proposed to integrate this heat transfer into an existing conceptual rain-flow transformation model, Hydrologiska Byråns Vattenbalansavdelning (HBV), to calculate the seasonal thaw depth and determine the components of water balance. The proposed integration is a novelty compared to the standard model, as it enables the physical and thermal properties of the soil to be taken into account. It was found that the proposed model, HBV-Heat, performs better than the stand-alone HBV model. Specifically, the average Nash–Sutcliffe efficiency (NSE) increases by 30% for the whole calibration period. In terms of the water balance components, the results are consistent with previous studies, showing that surface runoff represents 64% of the observed precipitation. [ABSTRACT FROM AUTHOR]

• The thermal-hydraulic code HYDRA-IBRAE/LM allows modeling installations with lead coolant. • The HYDRA-IBRAE/LM code is validated on the experiments conducted with lead coolant. • Flow regime map and closure relations for lead coolant modelling have been formulated. • A representative database of experimental data obtained for lead has been formed in Russia. The paper overviews the challenges associated with the development of a system thermal-hydraulic code applied for lead coolant by the example of a Russian system thermal-hydraulic code HYDRA-IBRAE/LM. It presents the PIRT describing relevant thermal-hydraulic phenomena that are to be simulated to model operational transients and accidents of Russian lead-cooled reactor BREST-OD-300. The paper also mentions the points in favor of using three-fluid model as a basic one. The results of evaluation and selection of lead coolant closure relations, that could be used in system thermal-hydraulic code, are presented. The paper demonstrates that heat transfer in the lead coolant may be calculated using closure relations obtained for the other liquid metal coolants introducing correction factors depending on the value of contact thermal resistance caused, for example, by oxide films present at the surface. The paper presents recommended properties of the lead coolant and summarizes experimental research findings of the Russian project PRORYV that can be used to validate system thermal-hydraulic codes. The paper discusses validation results for HYDRA-IBRAE/LM code based on experiments carried out using a BREST-OD-300 steam generator model and those with lead coolant cooldown due to argon injection. [ABSTRACT FROM AUTHOR]

The results of fundamental and applied research aimed at ensuring safe working conditions in terms of the thermal factor in the development of deep deposits of solid minerals are presented. The current parameters of the thermal regime of operating deep mines and mining plants in Russia are given. A description of the methodology developed for determining effective measures for managing the thermal regime of mining enterprises, mathematical models, and tools used to calculate the parameters has been given. Promising directions of research in the field of ensuring safe and efficient mining in conditions of unfavorable thermal conditions at great depths have been presented. [ABSTRACT FROM AUTHOR]

Equations are derived for mean friction and heat-transfer coefficients to solve problems of updating industrial plants for getting oil fractions based on application of approximate method for modeling momentum and heat transfer in heat exchangers with surface intensifiers. The Deissler and Van-Driest turbulent boundary-layer model is used for the turbulent viscosity function for a flat smooth wall. An equation is derived for the Stanton number using Chilton-Colburn hydrodynamic analogy, and agreement with the known analogy is shown. Identical local properties of turbulent motion in the boundary layer on a plate and in the wall layer of a tube and the conservative properties of the laws of friction and heat transfer to turbulences, which are taken account of parametrically, are used for modeling momentum and heat transfer in channels with surface intensifiers. Equations are derived for the mean tangential stress in the channels with intensifiers and for the Nusselt number using a dissipative model. The results of calculations and comparison with the known experimental investigations are given for tubes with surface wire inserts, with spiral finning and rectangular projections for transformer oil at Reynolds numbers 200 < Re < 2000. Thus, the adequacy of the developed mathematical model is proved in a wide range of operating and design parameters and thermophysical properties of liquids and gases. Further, the hydraulic resistance of the channel is the key experimental information about the object of modeling. Examples of use of mathematical model for designing and commissioning heat exchangers in petroleum fuels fractionating plants at industrial enterprises in the Russian Federation and abroad are given. [ABSTRACT FROM AUTHOR]

Exploration of confined swirled flows in the former USSR and present-day Russia has a long history and is presented by numerous publications, mostly written in Russian. The obtained results have been put to practical use in different areas of chemical, energy, and processing industries. In view of the process intensification concept, such characteristics of confined swirled flows may be considered unique: high centrifugal gravity, elongation of trajectories, the presence of internal separation zones, energy separation phenomena, and efficient mass/heat transfer in the absence of any moving parts. For instance, high gravity provides an excellent opportunity for multiphase flow stabilization, preventing the appearance of nonuniformities and stability loss, while enhancement of various driving forces acting on the reaction medium takes place. This review is devoted to outlining the main research trends and to discuss the most essential practical implementations in the subject matter done up until now. It is not foreseen to embrace the whole area of swirled flow investigations in the world, but only covers most of the significant ideas and applications contributed in by former Soviet and Russian scientists and engineers. Shortcomings and difficulties of using swirled flows are also briefly discussed. [ABSTRACT FROM AUTHOR]

• PARAMETER-SF1 test reproduces key processes of bundle degradation and top reflooding. • Reflooding of molten core may produce intensive oxidation. • Negative effects of reflooding should be considered in severe accidents management. • SOCRAT can predict VVER fuel behavior in severe accident conditions with reflooding. The paper discusses the results of numerical assessment of LWR fuel bundle degradation phenomena during heating up in a flowing steam and top flooding with water under severe accident conditions that were investigated in the PARAMETER-SF1 test. The simulation was performed with the code SOCRAT that is widely used in Russia for safety assessment of VVER-type NPP under severe accident conditions. A set of interacting processes, including heat transfer, fuel liquefaction, oxidation of fuel rods claddings, melt relocation and oxidation, hydrogen generation is discussed. PARAMETER-SF1 was the first test in the PARAMETER program that comprised several tests with different configurations of the VVER bundle flooding (top, bottom, and combined). Investigation of the phenomenology during flooding of an overheated core at the early phase of severe accident when core keeps a mainly rod-like geometry is extremely important for understanding the possibilities and conditions for implementing the measures of severe accident management at LWR NPPs. [ABSTRACT FROM AUTHOR]

The contribution is focused on investigating the heat transfer via natural convection which originated as an effect of changed air density by heating the horizontal sample in the area given. For this research we used samples of a new material made in the Russian Federation – the foam concrete which was reinforced by PET fibres. The samples were heated by an electric heating device from the bottom. The temperature fields originating above the horizontal sample surface were visualised by means of the holographic interferometric contactless method in real time. The holographic interferograms of the temperature field were analysed, and then the local heat transfer parameters were calculated: the heat transfer coefficient α, and the heat conductivity coefficient λ. [ABSTRACT FROM AUTHOR]

The article discusses the methods of estimating the anthropogenic heat fluxes in urban and industrial territories in Moscow, Russia . It explains the use of direct measurements of the heat fluxes, remote satellite measurements, and summing of all consumers of the heat and electric energy in the city for estimating anthropogenic heat flux in cities including Toulouse, Lodz, and Manchester. Moreover, a database on the energy consumption, population, and area of the largest urban agglomerations in Russia and in the world based on the analysis of the national statistical data were developed. Also cited is the idea of constructing the agglomeration circles comparable by their area with other megapolises and to focus on the administrative boundaries.

The proposed method of temperature labeling makes it possible to study the convective heat transfer by fast water flows. A filtration experiment on the transfer of heated moisture in the plow layer of a light loamy soddy-podzolic soil of Moscow region has been performed. The high unevenness of the front of the water migration in the experiment is related to the spatial distribution of the major pores and leads to sharp changes in the soil temperature. Temperature measurements in large lysimeters of Moscow State University filled with soddy-podzolic soils indicate that there are short periods of rapid changes in the soil temperature during the snowmelt season and upon heavy showers. These changes are related to intense gravitational water flows. In the soils with a distinct blocky structure of the upper horizon, the convective transfer of heat is better expressed than that in the soils with a crumb or granular structure of the plow layer. [ABSTRACT FROM AUTHOR]

Horizontal wind speed and vertical wind speed fluctuation data obtained from aircraft during the GEWEX Asian Monsoon Experiment-Siberia (GAME-Siberia) project revealed the development of a local circulation in the atmospheric boundary layer (ABL) near the Lena River, Siberia. Horizontal wind speed distributions showed regions where wind direction was opposite that of the synoptically dominant wind flow. Horizontal wind speed distributions and horizontally averaged vertical wind speed fluctuations with a 4-km cut-off distance were used to derive air stream vectors. The vectors showed the development of local circulations only over the upwind side of the Lena River on some days. Criteria for local circulation detection are suggested. Tower-based energy imbalances were observed at two flux-tower sites. Turbulent heat fluxes were underestimated relative to the available energy when mean downward flow dominated at the flux tower. This tower-observed energy imbalance might be related to the development of local circulations near the Lena River. [ABSTRACT FROM AUTHOR]

For a larch forest site near Yakutsk, energy and water fluxes are estimated and their variations are investigated using a one-dimensional land surface model with daily routine data. The estimation period is 1986-2000, including the period before the start of tower observation (1997) on the left bank of the Lena River. The land surface model includes three submodels: vegetation, snow cover, and soil. The model can calculate water and energy fluxes above and within the forest if meteorological data over the forest are given as input. Data used in this study are Baseline Meteorological Data in Siberia (BMDS) Version 3. This set comprises daily data of main meteorological elements. The procedure is as follows: (1) preparation of equations between routine Yakutsk data and larch tower data; (2) estimation of past meteorological data over the taiga using those equations; and (3) estimation of fluxes using the one-dimensional model. The date of leaf-out start is parameterized with soil temperature and accumulated air temperature. It corresponds to the green-up time obtained from satellite normalized difference vegetation index (NDVI) data. Estimated monthly deviation of net radiation, Rn is 10 Wm-2, its maximum is 20 Wm-2. The monthly deviation of latent heat flux, LE, is less than 12 Wm-2. Its warm season average is less than 7 Wm -2. Although the magnitude of LE is almost zero in December and January, and several Wm-2 aside from these 2 months, the sensible heat flux, H, sometimes becomes negative during the cold season. The variation of evapotranspiration is considerably smaller than that of precipitation. The evapotranspiration (E) normalized by potential evaporation (Ep), E/Ep is 0.37 0-44 in the warm season; it tends to be large when leaf-out starts early. The amount of evapotranspiration in the warm season can be estimated from Ep within an error of 5 mm using this relationship. [ABSTRACT FROM AUTHOR]