Thermal Engineering最新文献

{"title":"Simulation of Mixing of Single-Phase Fluids in T-Junctions","authors":"F. V. Tuponosov,&nbsp;V. I. Artemov,&nbsp;G. G. Yan’kov,&nbsp;N. S. Dushin,&nbsp;O. A. Dushina,&nbsp;A. V. Dedov","doi":"10.1134/S0040601523090070","DOIUrl":"10.1134/S0040601523090070","url":null,"abstract":"<p>The purpose of this study is to sample a procedure for numerical simulation and calculation of the processes of mixing in pipes of a T-junction (tee) of natural gas with the so-called “stripped” components, such as methane, hydrogen, and nitrogen, to obtain a mixture that can be used as a fuel at thermal power plants. The specific of fuel gas mixing is high Reynolds numbers of the simulated flows, which can be as high as Re = (5–10) × 10⁶. An analysis is presented of some experimental and modern computational studies of the processes of flow mixing in pipes and T-junctions. It is pointed out that the application of various well-accepted models for eddy viscosity or Reynolds stresses in the numerical simulation on the basis of Reynolds-averaged conservation equations yields a satisfactory agreement with experimental data on mixing flows in a T-mixer only with an unjustified decrease of the turbulent Schmidt (Prandtl) number to the value 0.1 or an increase of the known constant of turbulence models <i>C</i>_μ by a factor of 9. It can be concluded that eddy-resolving methods are unsuitable for the investigation of mixing processes in fuel pipeline joints due to high Reynolds numbers and a great length of the main pipe. An analysis of the predictions has revealed large fluctuations in the local ratio of the generation rate of the turbulent kinetic energy to the rate of its dissipation and a sharp decrease in its value averaged over the pipe cross section at a distance of several diameters from the starting point of mixing, which is not characteristic of pipe flows, mixing layers, or jets. An attempt was made to improve the predictive capabilities of the standard <i>k</i>–ε model for developed turbulence, while keeping the turbulent Schmidt number <span>({text{S}}{{{text{c}}}_{t}})</span> and the constant <i>С</i>_μ within the substantiated limits. An empirical formula for <span>({text{S}}{{{text{c}}}_{t}})</span> and a modification of the standard <i>k</i>–ε model, which takes into account the variability of <i>С</i>_μ according to the Rodi dependence carefully verified against data on various free flows, are proposed. Experimental investigations of isothermal mixing of air flows in a tee mixer, one of which contained tracers in the form of glycerin-based liquid microdroplets, were carried out. The profiles of hydrodynamic characteristics of the flow downstream of the tee were measured by the planar optical SIV method at a distance of 5.5<i>D</i> from the axis of the pipes' intersection. To verify the modified <i>k</i>–ε model, numerical simulation was performed of the mixing of gases and liquids in a tee mixer, and the predictions were compared with the experiment. The results are presented of the calculation of natural gas mixing in a tee mixer with a methane-hydrogen fraction from petrochemical facilities.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"70 9","pages":"673 - 692"},"PeriodicalIF":0.5,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4233940","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":"Biological Pollution of Technological Equipment and the Chemically Desalting Water Treatment Plant at a TPP (Review)","authors":"N. D. Chichirova,&nbsp;A. A. Filimonova,&nbsp;S. M. Vlasov,&nbsp;O. E. Babikov","doi":"10.1134/S0040601523090021","DOIUrl":"10.1134/S0040601523090021","url":null,"abstract":"<p>At thermal power plants, installations in contact with the water coolant are subject to biological contamination. This is due to a number of factors: the maintenance of favorable temperature regimes, the formation of stagnant zones, the constant supply of nutrients, the presence of large areas of equipment surfaces (pipelines, water storage tanks, the pipe surface of the condenser), the presence of various materials (ion-exchange resins, membranes), and changing climatic conditions. The fight against the formation of such pollution of thermal power equipment is very relevant today, although almost all TPPs carry out thorough preparation of additional and feed water. It should be noted that the control of the concentration of organic impurities in the liquid and vapor phases, as well as continuous monitoring, are rather laborious processes. Organic deposits and the presence of biofilms on the process equipment of circulating cooling systems (CCS), water treatment plants (WTP), and chemically treated water storage tanks lead to various production failures, emergencies, and a general decrease in the efficiency of heat and electricity generation. In this paper, foreign and domestic studies on the features of the formation and development of biofilms were reviewed. Current methods for detecting and assessing biological pollution are considered and traditional chemical, physical, electrochemical, acoustic, electromagnetic, and other methods of combating microorganisms and bacteria are described. It has been shown that the growth of bacteria significantly complicates the equipment-cleaning procedures and accelerates the process of scale formation. To effectively solve the problems of biological deposits, the development of methods for monitoring and controlling the formation of bacterial deposits, the preparation of additional water, and the maintenance of a water-chemical regime must be carried out differentially based on the identification of colonies of microorganisms using test systems. The previous works of the team of authors concerning the issues of pollution of the coolant of circulating cooling systems and water treatment plants at TPPs of the Republic of Tatarstan in the period from 2009 to 2022 are noted.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"70 9","pages":"665 - 672"},"PeriodicalIF":0.5,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4231620","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 Complex Study of Superheated Water Atomization","authors":"Yu. A. Zeigarnik,&nbsp;V. I. Zalkind,&nbsp;V. L. Nizovskii,&nbsp;L. V. Nizovskii,&nbsp;S. S. Shchigel’,&nbsp;I. V. Maslakova","doi":"10.1134/S0040601523090082","DOIUrl":"10.1134/S0040601523090082","url":null,"abstract":"<p>The article presents the results obtained from a complex study of heavily superheated water atomization during its discharging through various types of atomizers. A system for optic measurements of the spray cone dispersion structure has been developed and adjusted. The developed measurement system is based on measuring the scattering indicatrix of a probing laser emission in a wide range of angles (±45°) and solving the inverse scattering problem using the Mie theory. The results from a wide-scale experimental study of the spray cone dispersion structures produced by various types of nozzles with a sprayed water temperature of 140‒260°С and pressure at the nozzle exit equal to 0.1 MPa are presented, and the possibility of liquid atomization (to water droplets with a diameter of 5 µm or smaller down to submicrometer size) at high temperatures is shown. It has been found that the spray cone structure has a pronounced bimodal pattern: droplets 5‒8 µm in diameter combine with a submicrometer mode. With a growth of atomized water temperature, the fraction of submicrometer mode increases, reaching 60‒65 wt % at a temperature of 240‒260°С for cylindrical nozzles and 80‒90 wt % for convergent-divergent nozzles. For the case of water injection into the compressor of a gas turbine unit equipped with the TV-117 industrial grade turbine, the possibility of additionally controlling the peak power output has been demonstrated. It makes 4–8% per water flowrate percent (with respect to the air flowrate). The power output control quality is in compliance with the requirements of the UES of Russia network standards. Superheated water is finding an increasingly growing use for firefighting at power industry facilities, in closed premises, in spills of petroleum products, in performing operations with liquefied gas, and in other situations.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"70 9","pages":"693 - 700"},"PeriodicalIF":0.5,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4233954","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":"Efficiency of Multistage Filtration of Turbine Oil in the Oil-Supply System of Turbo Units","authors":"K. V. Osintsev,&nbsp;N. A. Pshenisnov,&nbsp;A. I. Pshenisnov","doi":"10.1134/S0040601523080074","DOIUrl":"10.1134/S0040601523080074","url":null,"abstract":"<p>The efficiency of multistage filters of the main oil tank (MOT) is analyzed. The efficiency of sequentially installed filters is determined by a power function in which the base is the stage skip factor <i>W</i>_<i>in</i> (assuming <i>W</i>_<i>in</i> = const for all filtering stages) and the exponent is the number of filtering stages <i>n</i>. Under the operating conditions of the hydraulic system, contaminants continuously enter the system and are removed by the filter. How the change in the transmittance <i>W</i>_<i>i</i> in the process of multistage filtration affects the purity of the oil in the operating system is analyzed. Oil tank filters were upgraded at the K-200-12.8 LMZ turbine unit (station no. 9) at Yuzhnouralskaya GRES. Instead of brass woven meshes, a filter material made of polyamide monofilaments (polyamide filter material) was installed. After the modernization of the coarse and fine filters, the oil became cleaner in the oil-supply system of the K-200-130 turbine unit (station no. 9), the amount of solid particles in it (in samples from the clean compartment of the MOT) with sizes of more than 10 microns decreased by 68 times, and the amount of water in the oil decreased by approximately three times; industrial purity corresponds to the eighth class of GOST 17216-2001. In practice, the operation of coarse and fine filters in one and two stages was also analyzed. When switching from single-stage to two-stage filtration, the purity of the oil became higher, and the amount of solid particles in it with sizes of more than 5 microns decreased by three times, while the amount of water in the oil by approximately 12 times. Increasing the number of filtration stages significantly increases the purity of the filtrate.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"70 9","pages":"659 - 664"},"PeriodicalIF":0.5,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4235131","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":"Investigation into the Influence of Temperature on the Formation of Nitrogen Oxides during the Staged Combustion of Low-Reactive Coal with the Use of Direct-Flow Burners","authors":"V. B. Prokhorov,&nbsp;S. L. Chernov,&nbsp;V. S. Kirichkov,&nbsp;V. D. Aparov","doi":"10.1134/S0040601523090057","DOIUrl":"10.1134/S0040601523090057","url":null,"abstract":"<p>Coal remains one of the main types of mineral fuel in Russia, especially in the Siberian and Far Eastern federal districts. At the same time, the requirements for reducing emissions of harmful substances into the atmosphere, including nitrogen oxides NO_<i>x</i>, are becoming tougher both in Russia and around the world. In this regard, it is promising to use the vortex method of coal combustion using slot burners and collective action nozzles with a stepped air supply for combustion. However, when burning low-reactivity coal, it becomes necessary to achieve high combustion efficiency, which can only be ensured with the correct organization of the furnace aerodynamics, including the location of burners and nozzles, as well as with the optimal distribution of the shares of primary, secondary, and tertiary air. Using the example of vortex combustion of lean Kuznetsk coal using direct-flow burners and nozzles, the possibility of reducing nitrogen oxide emissions during staged fuel combustion is considered. A boiler with a steam capacity of 500 t/h with solid ash removal was taken as an object of the study. Two schemes of coal combustion were chosen earlier with the help of numerical and physical modeling. According to the calculations, both schemes provide low heat losses with mechanical underburning, at the level of 0.7–1.9%. Numerical modeling of the vortex combustion process showed that high maximum temperatures in the fuel ignition zone at low air excesses do not contribute to the formation of nitrogen oxides, but, on the contrary, contribute to their suppression due to the increased concentration of pyrolysis products in the main combustion zone. The temperature at the initial stage of combustion should be approximately 2000 K, and this figure is more important than reducing the excess of primary air from 0.3 to less than 0.1.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"70 9","pages":"711 - 718"},"PeriodicalIF":0.5,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4231295","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 New Method for Determining the Aerodynamic Forces Arising in Turbine Seals","authors":"S. S. Dmitriev,&nbsp;B. N. Petrunin,&nbsp;V. V. Naumov,&nbsp;I. A. Nikitin","doi":"10.1134/S0040601523090033","DOIUrl":"10.1134/S0040601523090033","url":null,"abstract":"<p>The article presents an aerodynamic force calculation method that was developed and tested at the National Research University Moscow Power Engineering Institute’s (NRU MPEI) Department of Steam and Gas Turbines. By using the proposed method, it is possible to quickly estimate, as a first approximation, the nonconservative component of the aerodynamic force arising in turbine seals proceeding from the aerodynamic force value measured under steady-state conditions without resorting to conventional costly research methods. The possibility to calculate the aerodynamic force nonconservative component at any rotor rotation frequency under steady-state conditions is substantiated. The values of the aerodynamic force nonconservative component in the seal obtained using the new method according to the calculation expression proposed by A.G. Kostyuk were compared with the results of measuring this force for similar seal models carried out previously using the conventional methods: by means of a strain-gauge balance and from the readings in seal chamber drains. The new method for determining aerodynamic forces was then applied for estimating the blade row forces, which depend on the leak uniformity through the shroud seal and act on the R-26-17A annular turbine rotor cascade. The obtained values were compared with the data of studies carried out on the IT-1 experimental setup using the conventional method by means of strain-gauge measurements, and the comparison results have shown good agreement of the data. The proposed method makes it possible to obtain qualitatively and quantitatively valid results and can be used for comparing the seals having different configurations with respect to the nonconservative force component arising in them that can give rise to self-vibration of turbine machinery shaft lines. For perfecting the method, it is possible to use the models of rotor parts that do not need balancing and that are manufactured using inexpensive materials.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"70 9","pages":"650 - 658"},"PeriodicalIF":0.5,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4233939","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 Effectiveness of Film Cooling with Injection of Pulsating Air Flow (Review)","authors":"A. V. Shchukin,&nbsp;A. V. Il’inkov,&nbsp;V. V. Takmovtsev,&nbsp;I. A. Popov,&nbsp;A. L. Tukmakov,&nbsp;A. V. Starodumov","doi":"10.1134/S0040601523090069","DOIUrl":"10.1134/S0040601523090069","url":null,"abstract":"<p>An analytical review is presented of scientific publications with the results of physical and numerical simulation of the effect of the pulsating cooling air flow on the effectiveness of thermal cooling η, specifically on the airfoil part of turbine blades. The tests carried out under nearly full-scale conditions have revealed positive, variable, or negative effects of pulsations on the effectiveness of the film cooling. It has been found that a positive or negative effect of pulsations superimposed on the injected air flow is determined by the transport mechanisms in the film-cooling system, which are observed without pulsations. At the same time, fan-shaped holes give a higher local effectiveness of the film cooling compared to classical cylindrical holes not only in the steady-state case without changing the coolant flowrate but also in the case with pulsating flow injection. In the steady-state case, this occurs at a blowing ratio of <i>m</i> = 1.0, and that with the pulsating flow injection is at <i>m</i> = 1.5 and 2.0. This is caused by the more uniform coverage by the gas-air mixture of the cooled surface downstream of the section with pulsating air flow injection. Moreover, at <i>m</i> = 1.5 for holes of both shapes, the pulsating coolant flow with <i>m</i> = 1.5 offers a higher spanwise averaged effectiveness of film cooling, <span>(bar {eta },)</span> than the injected steady flow does. The examined methods for predicting the effect of pulsating flow injection on <span>(eta )</span> require only knowledge of the steady flow behavior and enable us to assess when pulsing would be beneficial or detrimental for the effectiveness of film cooling.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"70 9","pages":"639 - 649"},"PeriodicalIF":0.5,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4231619","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":"Experience of the Development of Geothermal Energy on the Example of Iceland","authors":"V. A. Butuzov","doi":"10.1134/S004060152309001X","DOIUrl":"10.1134/S004060152309001X","url":null,"abstract":"<p>Data on the geothermal resource base of Iceland are presented: 25 high-temperature (temperature over 200°C at the bottom) and 250 low-temperature (150°C) deposits. The similarity of the geological conditions and the main characteristics of thermal water intakes in Iceland and Kamchatka krai of Russia is noted. The analysis of the legal support of geothermal energy in Iceland, as well as the activities of the state institution Orkustofnun for licensing, research of geothermal deposits, and the creation of the world’s largest library of geothermal literature, was carried out. The process of implementation of the IDDP state program for drilling and testing wells at the foot of the Krafla volcano at supercritical parameters (SCP) of fluids is described. The main characteristics of eight geothermal power plants (GeoPP) with a total capacity of 753 MW with electricity generation in 2021 of 6208 GW h are given and thermal schemes and cycles are described. It is indicated that the most powerful GeoPP in Iceland is Hellisheiði (303 МW), the geothermal coolant of which is supplied to Reykjavik, located at a distance of 19.5 km from it. This station is equipped with an installed system for the utilization of carbon dioxide into carbonate underground rocks. Power units with binary cycles were built at two GeoPPs: Husavik (2 MW) in the Kalina cycle and Svartsergi (7 × 1.2 MW) with organic coolant. It is noted that Iceland has the world’s largest geothermal heat generation (2373 MW, 9340 GW h (2021)), with heating predominating (1650 MW; 6840 GW h (2021)). The most powerful heat-supply system in the country and in the world, in Reykjavik, is described: its capacity is 1150 MW and the length is 2230 km. Data are presented on the nonenergy use of geothermal water in fish farms, swimming pools, greenhouses, and carbon dioxide utilization plants. It is concluded that the experience of Iceland is especially significant for the development of geothermal energy in Russia.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"70 9","pages":"701 - 710"},"PeriodicalIF":0.5,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4234839","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":"Heat Load Prediction for District Heating Systems with Temporal Convolutional Network and CatBoost","authors":"C. Han,&nbsp;M. Gong,&nbsp;J. Sun,&nbsp;Y. Zhao,&nbsp;L. Jing,&nbsp;C. Dong,&nbsp;Z. Zhao","doi":"10.1134/S0040601523090045","DOIUrl":"10.1134/S0040601523090045","url":null,"abstract":"<p>Accurate heat load prediction is essential for heat production and refined management of district heating systems (DHSs). More advanced technology can often achieve more accurate forecasts. This paper suggests using temporal convolutional network (TCN) and categorical boosting (CatBoost) for heat load prediction. To test the performance of TCN and CatBoost in heat load prediction missions, two additional benchmark models, the decision tree model (DT) and the statistically based multiple linear regression (MLR), are built for comparison. A DHS in Tianjin, China, is used as the study case. Two historical operational characters (day-ahead heat load and hour-ahead heat load) and four meteorological characters (outdoor temperature, relative humidity, wind scale, and air quality index) are selected as input features for the models. The prediction results of every model on the test set are displayed and discussed. The experimental findings indicate that the prediction results of TCN and CatBoost are more accurate than the traditional prediction models, while the modeling process of CatBoost is simpler. Overall, TCN and CatBoost are potential heat load prediction methods.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"70 9","pages":"719 - 726"},"PeriodicalIF":0.5,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4231296","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 Study of R113 Refrigerant Boiling Processes in a Horizontal Tube Bundle under High Heat Flux Conditions","authors":"O. O. Mil’man,&nbsp;V. B. Perov,&nbsp;G. G. Yan’kov,&nbsp;A. V. Kondrat’ev,&nbsp;A. V. Ptakhin,&nbsp;V. S. Krylov,&nbsp;A. P. Zheleznov,&nbsp;A. A. Zhinov","doi":"10.1134/S0040601523080062","DOIUrl":"10.1134/S0040601523080062","url":null,"abstract":"<p>Energy-saving technologies are among the priority development lines of Russia’s power industry. In recovering the rejected heat from geothermal sources, especially those located in cold climatic zones in which there is no access to service cooling water resources, it is profitable to use organic coolants, e.g., CFC refrigerants, as working fluid for dry cooling towers. The properties of such coolants have, as a rule, been studied to a sufficient detail in the region of low temperatures, because they are mainly used as working fluids for refrigeration systems at moderate heat fluxes. To obtain data on the boiling of organic coolants on a tube bundle for taking into account the influence of bundle lower tubes on the heat transfer in the upper tubes, a vapor generator mockup with a horizontal tube bundle was developed. High-pressure water served as the heating medium; and electric heaters were provided for additionally heating the CFC refrigerant to a level close to the saturation temperature. The tube bundle includes twelve tubes arranged in three rows along the height: the central row consists of four measurement tubes, and two lateral rows consist of auxiliary tubes. Eight thermocouples are installed at the top and bottom in the slots of the central row heat-transfer tubes for measuring the surface temperature. For the lower and upper rows in the bundle, boiling heat-transfer coefficients were obtained in a wide range of specific heat fluxes. It is shown that the boiling on the upper rows is significantly more (by 30–35%) intense than it is on the lower rows.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"70 8","pages":"595 - 602"},"PeriodicalIF":0.5,"publicationDate":"2023-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4970575","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}