Thermal Engineering最新文献

{"title":"A Model of Transition from Stable Film Boiling to an Intense Heat Transfer Regime","authors":"T. A. Gubanova,&nbsp;P. K. Kanin,&nbsp;I. A. Molotova,&nbsp;V. V. Yagov","doi":"10.1134/S0040601526700151","DOIUrl":"10.1134/S0040601526700151","url":null,"abstract":"<p>The article presents the basic statements of the hypothesis put forward on the factors causing the occurrence of intense heat transfer regime during film boiling of subcooled liquid. A new relationship for the temperature difference corresponding to the moment at which transition to fast cooling regime occurs is derived. This relationship takes into account the thermophysical properties of cooled surface and roughness scale on it, the thermophysical properties of cooling liquid and its subcooling. The model has been verified against experimental data under the conditions of free bulk motion of liquid. Unlike our previously published model versions, the liquid subcooling is now taken into account in a more natural way, namely, by the cooling liquid properties and its flow dynamics rather than by introducing empirical corrections. Separate attention is paid to experimental data on cooling metal bodies with the known surface irregularity scale, because the developed relationship depends quite strongly on it. For verification purposes, we collected experimental data on the cooling of spherical and cylindrical samples made of stainless steel, nickel, and copper with various coatings (chromium carbide, gold, and silver), carbon steel, titanium, and FeCrAl and zirconium alloy in water, ethanol, and water–ethanol mixtures with different concentrations. Additional experiments on cooling a copper ball with nickel coating in subcooled water were carried out. For verifying the model, we used experimental data of other researchers on cooling in subcooled water of heated bodies made of zirconium, stainless steel, Inconel, and Zircalloy. The calculation carried out using the newly developed mode has demonstrated good agreement between the obtained results and predominant amount of experimental data.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"73 6","pages":"433 - 444"},"PeriodicalIF":1.3,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148519452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Influence of Local Heating on Heat Transfer in a Thin Liquid Layer","authors":"S. Ya. Misyura,&nbsp;R. I. Egorov,&nbsp;A. S. Zaitsev,&nbsp;V. V. Terekhov,&nbsp;V. S. Morozov","doi":"10.1134/S0040601526700163","DOIUrl":"10.1134/S0040601526700163","url":null,"abstract":"<p>In recent years, specialists have paid significant attention to development of heat transfer enhancement methods that make it possible to reduce energy consumption and increase the heat transfer coefficient. Application of such methods is of special importance if there are high local heat fluxes and compact sizes of heat transfer devices. The use of local heating makes it possible to decrease energy consumption and enhhance the transfer processes. However, many mechanisms of heat transfer and ways for improving it still remain insufficiently understood. In the present study, the effect the laser heating power and its modulation frequency (local heating) have on heat transfer in a 1.4–5.1 mm thick liquid layer was considered. In carrying out the study, the particle image velocimetry (PIV) and particle tracking velocimetry (PTV) methods were applied for measuring velocity fields, and infrared recording was used for analyzing the temperatre fields. In the laser power modulation mode (0.05–1 Hz), high heat transfer intensity is retained when the average power is decreased by 40%. With such mode, a flow with numerous small vortices is generated, but the convection velocity in the liquid layer horizontal section decreases insignificantly (by 6–7%). The average convection velocity depends on the laser power oscillation frequency. With increasing the laser impact power by a factor of 2.5, the heat transfer coefficient increases by 20–25%. An analysis of the velocity field correlation function has revealed that with increassing the liquid layer height and decreasing the laser power, the flow becomes more chaotic in nature, which points to a change of the flow regimes. The temperature field and its nonuniformity depend essentially on the layer height and heating power. With a small layer height (1.4 mm), the heated area is localized in the center, and the longitudinal temperature gradient is maximal, whereas with a large height (5.1 mm) the temperture is distributed along the layer radius more uniformly.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"73 6","pages":"445 - 456"},"PeriodicalIF":1.3,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148519453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ion Exchange or Reverse Osmosis: Preferences for Water Treatment","authors":"S. L. Gromov","doi":"10.1134/S0040601526700138","DOIUrl":"10.1134/S0040601526700138","url":null,"abstract":"<p>Approaches used to compare the possibilities and economic efficiency of ion exchange and reverse osmosis separation technologies in obtaining demineralized water are considered. The article shows the way in which the economic equilibrium point position on the feed water total dissolved solids (TDS) scale may change depending on the choice of technical solutions in implementing ion exchange and reverse osmosis, on the ratio between the tariffs for electricity and costs of chemicals used for regenerating ion exchange resins, on the technology for water pretreatment before the main demineralization stage, on the water treatment plant capacity, and also on other factors influencing the operating costs (OPEX). It is demonstrated that under the conditions in Russia, namely, at a relatively low cost of electricity and rather costly chemicals, the most economically efficient and technologically sustainable water treatment plant layout used to obtain demineralized water with the residual electrical conductivity equal to 0.1 µS/cm from surface sources in a very wide TDS range is a combination of one pass RO with separate Н‒ОН ion exchange implemented according to the UPCORE countercurrent regeneration process. The spectrum of technical solutions that shall mandatorily be compared at the stage of water treatment plant design feasibility study has been determined, and it is emphasized that the choice of the optimal process of water demineralization can only be made provided that all factors and conditions of implementing a particular project are subjected to a competent and comprehensive analysis. The data presented testify that attempts of water demineralization based on the sole membrane separation methods (so called Integrated Membrane Technologies—IMT) may result in degraded economic efficiency of water treatment plants.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"73 6","pages":"492 - 500"},"PeriodicalIF":1.3,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148519454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Mathematical Model of the Tire Pyrolysis Process in Shaft Reactors","authors":"L. B. Director,&nbsp;V. A. Lavrenov,&nbsp;A. L. Shevchenko","doi":"10.1134/S0040601526700126","DOIUrl":"10.1134/S0040601526700126","url":null,"abstract":"<p>The article presents a mathematical model of a vertical cylindrical reactor heated by flue gases for pyrolysis of spent tire chips. The tire chips layer was modeled by spheres of the same diameter with simple cubic packing; the model took into account the dependence of layer porosity and permeability on the section height coordinate and raw material conversion degree. For describing the kinetics characterizing the thermal decomposition process of rubbers included in the tire composition, we used a model with one global kinetic step and the reaction products generation selectivity condition, which depends only on temperature. The system of 2D unsteady differential equations of heat and mass transfer and kinetics was solved numerically based on the Thomas algorithm for tridiagonal matrices. The article presents the results of mathematical model verification against the data of thermogravimetric analysis and experiments on laboratory facilities, which confirm the model adequacy. The article also presents the results of calculating the pyrolysis process characteristics (the mass of raw material processed and the yield of main products – pyrolysis gas, liquid fraction, and carbon residue) and comparative efficiency of the reactors of two types: a fixed bed reactor (FBR) and a move bed reactor (MBR), the bed is which is moved by periodically unloading a part of carbon residue in the reactor lower part and synchronously charging tire chips into the reactor upper part. The reactor autothermal operation conditions have been determined. The energy flows have been analyzed, and the parameters of reactor optimal operation conditions have been determined.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"73 6","pages":"457 - 468"},"PeriodicalIF":1.3,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148519457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Investigation of Burning Furnace of Sulfur-Containing Exhaust Gas","authors":"Liang Zhang,&nbsp;Penghui Xie,&nbsp;Jiyu Zheng,&nbsp;Changquan Hu,&nbsp;Xiaobo Feng,&nbsp;Lu Yu,&nbsp;Hui Liu","doi":"10.1134/S0040601524601128","DOIUrl":"10.1134/S0040601524601128","url":null,"abstract":"<p>Triethylene glycol (TEG) dehydration is a commonly used method for natural gas dehydration. However, the sulfur-containing exhaust gases generated during dehydration are challenging to eliminate. Therefore, developing an effective method for removing sulfur-containing tail gas is essential. This paper analyzes the characteristics of various waste gas desulfurization technologies, proposes a combined approach of alkaline absorption followed by combustion for tail gas treatment, and proposes a new type of burner structure that enhances both the gas intake method and the structure of the burning furnace. By numerical methods, the internal flow field and combustion characteristics of the combustor are investigated, the Realizable <i>k</i>–ω turbulence model and eddy-breakup combustion model are employed in the computational model to predict species composition, flow field, and temperature. The simulation results show that this scheme can better remove the sulfur-containing components in the exhaust gas. The <span>({text{H}_{2}}text{S})</span> concentration is reduced from 0.2630 to 0.0009% after the treatment, which is sufficiently decomposed. Additionally, this paper compares the computational model with other structures and predicts gas residence time in the combustion furnace, illustrating the model’s advantages in removing sulfurous exhaust gases and enhancing combustion effectiveness. This paper proposes a novel method for treating sulphurous exhaust gases, including adding a cyclone structure at the furnace gas inlet, which improves the degree of mixing and combustion temperature. This integration not only extends the equipment’s service life but also reduces its overall size.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"73 6","pages":"419 - 432"},"PeriodicalIF":1.3,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148519451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combustion of Brown Coal, Anthracite, and Their Mixtures in High-Pressure Steam–Oxygen Mixture","authors":"S. A. Alekhin,&nbsp;O. N. Fedyaeva","doi":"10.1134/S0040601525601585","DOIUrl":"10.1134/S0040601525601585","url":null,"abstract":"<p>The article presents the results of a study of combusting brown coal (BC), anthracite (A), and their mixtures taken in the ratios (BC : A) equal to 7 : 3, 1 : 1, and 3 : 7 in terms of organic mass in water–oxygen fluid at the pressure <i>р</i> ≤ 25 MPa, which was carried out for the first time. The experiments were carried out with coals heated in the Н₂О/О₂ fluid medium at a rate of 1°С/min to 550°С and in pumping the fluid through the bed of coal mixture (BC : A = 7 : 3) and heating the reactor at a rate of 1.5°С/min to 420°С. It is shown that the coals and their mixtures are oxidized in the autoclave regime according to the thermal explosion mechanism. This facilitates almost complete combustion of organic carbon for a few tens of seconds at relatively low temperature (below 700°C). The ignition temperature and combustion dynamics of mixtures with predomination of one of coals (BC or A) in the autoclave regime are similar to the combustion characteristics of this coal; the combustion of coals with the equal content of BC and A proceeds in two stages. It has been found that in pumping the Н₂О/О₂ fluid through a bed of coal mixture, their intense combustion at 230−300°С is accompanied by the generation of combustible components and their entrainment by steam flow. The organic carbon combustion rate under these conditions is governed by the oxygen flowrate supplied into the reactor. The obtained study results can become a basis for the development of promising technologies for combustion of coals and coal enrichment waste in high pressure steam to yield a high-enthalpy heat carrier.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"73 6","pages":"389 - 401"},"PeriodicalIF":1.3,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148519455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal Conversion Parameters of Composite Liquid Fuels on the Basis of Petroleum Sludge and Additions of Hydrocarbon Origin","authors":"K. Yu. Vershinina,&nbsp;D. M. Golovko,&nbsp;D. S. Romanov,&nbsp;V. V. Dorokhov","doi":"10.1134/S004060152670014X","DOIUrl":"10.1134/S004060152670014X","url":null,"abstract":"<p>With the aim to develop petroleum sludge thermal recycling technologies, the parameters characterizing the combustion of these sludges in mixtures with spent oils, diesel fuel, and methanol are studied. In combusting petroleum sludge without additions, sulfur and nitrogen oxide emissions are recorded in amounts four times higher than those produced in combusting diesel fuel. If petroleum waste is mixed with spent oils, the specific concentrations of SO₂ and NO (recalculated for the heating value and mass of fuel combusted) decrease by 20–29 and 7–10%, respectively, and by 30 and 35–40%, respectively, when combined with diesel fuel. The study results testify that there are wide possibilities for reducing the burden on the environment by subjecting petroleum sludges to thermal recycling. Their thermal inertia at the evaporation and thermal decomposition stage decreased most efficiently when mixed with methanol and diesel fuel. Despite the difference in some individual characteristics of the additions studied, all of them had a commensurable effect on the change in the integral indicator of petroleum sludge thermal recycling efficiency—it increased by 12–16%. It is shown that diesel fuel is the most promising addition. The introduction of this component results not only in obtaining better environmental and power performance of the process, but also in that the petroleum sludge viscosity is reduced by four times, due to which the fuel atomization is improved, and its more complete combustion is achieved in power generating boilers of various types. The results of experiments carried out on two facilities of different scales can serve as substantiation of the need to develop the problem area of petroleum sludge thermal treatment with heat generation.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"73 6","pages":"402 - 418"},"PeriodicalIF":1.3,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148519450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Application of Deep Machine Learning Methods for Designing Turbomachinery Blade Cascades","authors":"V. V. Popov,&nbsp;I. Yu. Gavrilov,&nbsp;V. A. Tishchenko,&nbsp;K. A. Berdyugin,&nbsp;A. A. Tishchenko,&nbsp;A. O. Smirnov,&nbsp;D. G. Sokolov","doi":"10.1134/S0040601526700096","DOIUrl":"10.1134/S0040601526700096","url":null,"abstract":"<p>The article presents an integrated procedure for 3D designing of turbomachinery stages, which combines the use of a blade passage shape parametric description and neural networks. The procedure has at its heart a blade parametric model on the basis of Bezier curves, which employs eight to ten controlling parameters (thickness, edge radiuses, inlet/outlet angles, etc.), due to which it becomes possible to produce smooth profiles and reduce the problem dimensionality. By using such approach, a fully connected neural network for predicting the profile loss coefficient in nozzle vane cascades has been developed. The network architecture includes three hidden layers with Swish activation functions and Dropout regularization. The network was trained on a dataset of 2D CFD computations covering a wide range of geometric parameters, Mach numbers (0.6–0.95), and Reynolds numbers (1.6 × 10⁵–1.1 × 10⁶). The trained model’s median prediction error amounted to less than 0.24%. The procedure was applied for designing the steam turbine last stage. Nine nozzle vane sections have been designed and optimized, and the 3D cascade has been shaped. The verification carried out using 3D CFD simulation in the ANSYS CFX environment has confirmed the approach adequacy: the loss distribution pattern over the nozzle vane cascade height is in qualitative agreement with the calculation results. Comparison carried out for middle sections has shown satisfactory quantitative coincidence (the average loss predicted using the neural network was equal to 4.24% against 4.83% estimated from CFD simulation). In addition, the problem of improving the erosion resistance has been solved. For the near-tip section at the nozzle vane cascade relative height equal to 0.75, its separation performance has been optimized. By using the second neural network, which predicts the droplet motion trajectories and points at which they collide with the surface, the leading edge radius and the suction and pressure side curvatures were varied. The aim of the optimization was to enhance the moisture deposition on the profile surface for its subsequent controlled removal through the moisture removing slit, which would help decrease the rotor blade erosion wear. It is shown that by integrating the parametric models and neural network, it is possible to develop a tool for effectively designing turbomachinery stages, predicting the aerodynamic characteristics, and solving a problem connected with two-phase flows.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"73 5","pages":"315 - 325"},"PeriodicalIF":1.3,"publicationDate":"2026-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148342832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Erratum to: Heat Transfer and Pressure Drop in Main Heat Exchangers of a Thermal Oil ORC-Unit (Review)","authors":"I. S. Antanenkova,&nbsp;Yu. A. Geller,&nbsp;M. M. Vinogradov,&nbsp;E. A. Gorbunova,&nbsp;V. I. Kuznetsov","doi":"10.1134/S0040601526170015","DOIUrl":"10.1134/S0040601526170015","url":null,"abstract":"","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"73 5","pages":"387 - 387"},"PeriodicalIF":1.3,"publicationDate":"2026-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1134/S0040601526170015.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148342850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Influence of Restorative Thermal Treatment on the Mechanical Properties of Pipes Made of Steel 20 Affected by Hydrogen Embrittlement","authors":"A. V. Nechaeva,&nbsp;V. V. Shagalaev,&nbsp;A. S. Zavorin,&nbsp;N. Yu. Gurkina","doi":"10.1134/S0040601526700084","DOIUrl":"10.1134/S0040601526700084","url":null,"abstract":"<p>In the contemporary power industry, a sector in which the reliable and efficient operation of equipment plays the key role, the problem of failures occurred in waterwall tubes of industrial power generating boilers caused by growing hydrogen embrittlement (HE) of their metal becomes increasingly more pressing. The article presents the results of studying the effectiveness of using integrated restorative thermal treatment (RTT) aimed at eliminating hydrogen embrittlement of the metal (grade 20 steel) of the boiler heat transfer surface tubes. In contrast to previous studies, focus was placed on the tests of annular samples. In the course of such tests, a complex stressed state is produced, which the tubes experience under real conditions (a combination of tensile and bending stresses) and turn to be very sensitive to hydrogen embrittlement. The study results have shown that, owing to the proposed integrated thermal treatment schedule, which includes degassing, homogenization, and normalization stages, the metal state becomes significantly better. Mechanical tests have shown that with such thermal treatment the metal has gained essentially better strength and plasticity: the ultimate strength of annular samples has increased by 2.8 and 6.2 times, and their relative elongation has increased by two and three times at room (+20°С) and operating (+400°С) temperature, respectively. It has been confirmed that the cracks have become fewer in number and smaller in size, that the metal ferrite-pearlite structure has restored, and the pattern of fractures has changed from brittle to viscous in nature. An analysis of fractures and the abnormalities in the way the notch toughness manifests itself at different temperatures have confirmed the HE mechanism connected with accumulation of graphite at grain boundaries. It has been determined that in implementing the developed thermal treatment schedule, the regenerative processes in the metal are intensified, and the metal partially restores its performance characteristics. Thermal treatment is a promising method for extending the service life of power generating boiler heat transfer surfaces; however, for the metal properties to become fully in line with their standard values, the treatment technological parameters should be further optimized.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"73 5","pages":"380 - 386"},"PeriodicalIF":1.3,"publicationDate":"2026-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148342893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}