Pub Date : 2024-09-18DOI: 10.1134/s1810232824030093
A. D. Nazarov, N. B. Miskiv, A. F. Serov, V. N. Mamonov
Abstract
Single-phase heat transfer from a vertical titanium plate with area of 140 mm2 to a water droplet flow (spray) normal to the surface of the heat exchanger was studied experimentally. Two models of commercial hydraulic full-cone nozzles with different characteristics of flow and spray pattern were used, the average mass flow rate being 2.4 kg/m2s to 6.46 kg/m2s. The maximum heat flux density of the heater was 204 kW/m2. The area-averaged heat transfer coefficient was found to be highly dependent on the mass flow rate of the coolant. The average droplet diameter and the outflow velocity from nozzle openings appear to have secondary influence on single-phase heat transfer.
{"title":"Single-Phase Cooling of Large Surface by Water Droplet Flow","authors":"A. D. Nazarov, N. B. Miskiv, A. F. Serov, V. N. Mamonov","doi":"10.1134/s1810232824030093","DOIUrl":"https://doi.org/10.1134/s1810232824030093","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Single-phase heat transfer from a vertical titanium plate with area of 140 mm<sup>2</sup> to a water droplet flow (spray) normal to the surface of the heat exchanger was studied experimentally. Two models of commercial hydraulic full-cone nozzles with different characteristics of flow and spray pattern were used, the average mass flow rate being 2.4 kg/m<sup>2</sup>s to 6.46 kg/m<sup>2</sup>s. The maximum heat flux density of the heater was 204 kW/m<sup>2</sup>. The area-averaged heat transfer coefficient was found to be highly dependent on the mass flow rate of the coolant. The average droplet diameter and the outflow velocity from nozzle openings appear to have secondary influence on single-phase heat transfer.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1134/s1810232824030159
A. S. Anshakov, O. G. Volokitin, P. V. Domarov
Abstract
The paper focuses on computational and experimental studies of processing ash residues from an incineration plant (IP). To prevent environmental contamination, it is required to melt IP ash and slag to obtain a useful product with neutral properties. Combined heating of ash and slag is proposed, and the time for melting of dispersed particles of silicon dioxide ((alpha) quartz) under the action of arc plasma and resistive heating is calculated.
{"title":"Features of Plasma-Thermal Melting of Ash and Slag from Incineration Plant1","authors":"A. S. Anshakov, O. G. Volokitin, P. V. Domarov","doi":"10.1134/s1810232824030159","DOIUrl":"https://doi.org/10.1134/s1810232824030159","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The paper focuses on computational and experimental studies of processing ash residues from an incineration plant (IP). To prevent environmental contamination, it is required to melt IP ash and slag to obtain a useful product with neutral properties. Combined heating of ash and slag is proposed, and the time for melting of dispersed particles of silicon dioxide (<span>(alpha)</span> quartz) under the action of arc plasma and resistive heating is calculated.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1134/s1810232824030020
O. N. Fedyaeva, A. P. Grebennikov, A. A. Vostrikov
Abstract
The paper presents the results of a study of oxidation of bulk bismuth samples by oxygen, water vapor, and water-oxygen fluid in a reactor heated to 873 K at a rate of 1 K/min with high-density reagents ((rho_{{rm O_{2}}}le0.62) and (rho_{{rm H_{2}O}}le5.24) mol/dm3). The results include temperature dependences of the pressure of the reaction mixtures. The rate of oxygen consumption is found from these dependences through the Redlich–Kwong equation of state. Formation of dense oxide film during the oxidation of bismuth in the O2 environment was shown. No oxide formation was detected during treatment of bismuth with water vapor. The combined action of O2 and H2O molecules enhances the oxidation of bismuth and leads to formation of oxides of different compositions and morphologies. At (T>720) K, the bismuth oxidation rate was observed to increase due to the higher pressure of saturated bismuth vapor.
摘要本文介绍了在一个加热到 873 K 的反应器中，氧气、水蒸气和水氧流体以 1 K/min 的速度和高密度试剂（(rrho_{/rm O_{2}}}le0.62) and(rho_{/rm H_{2}O}}le5.24) mol/dm3）对块状铋样品进行氧化的研究结果。结果包括反应混合物压力的温度依赖性。通过 Redlich-Kwong 状态方程，可以根据这些依赖关系求出氧气消耗率。结果表明，铋在氧气环境中氧化时会形成致密的氧化膜。用水蒸气处理铋时没有检测到氧化物的形成。O2 和 H2O 分子的共同作用增强了铋的氧化，并导致形成不同成分和形态的氧化物。在 (T>720) K 条件下，由于饱和铋蒸汽的压力较高，铋的氧化速率被观察到有所增加。
{"title":"Features of Oxidation of Bismuth by High-Density Water-Oxygen Fluid","authors":"O. N. Fedyaeva, A. P. Grebennikov, A. A. Vostrikov","doi":"10.1134/s1810232824030020","DOIUrl":"https://doi.org/10.1134/s1810232824030020","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The paper presents the results of a study of oxidation of bulk bismuth samples by oxygen, water vapor, and water-oxygen fluid in a reactor heated to 873 K at a rate of 1 K/min with high-density reagents (<span>(rho_{{rm O_{2}}}le0.62)</span> and <span>(rho_{{rm H_{2}O}}le5.24)</span> mol/dm<sup>3</sup>). The results include temperature dependences of the pressure of the reaction mixtures. The rate of oxygen consumption is found from these dependences through the Redlich–Kwong equation of state. Formation of dense oxide film during the oxidation of bismuth in the O<sub>2</sub> environment was shown. No oxide formation was detected during treatment of bismuth with water vapor. The combined action of O<sub>2</sub> and H<sub>2</sub>O molecules enhances the oxidation of bismuth and leads to formation of oxides of different compositions and morphologies. At <span>(T>720)</span> K, the bismuth oxidation rate was observed to increase due to the higher pressure of saturated bismuth vapor.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1134/s1810232824030044
D. S. Gluzdov, E. Ya. Gatapova
Abstract
The paper presents the implementation of a user-defined function (UDF) for the Navier boundary condition in the Fluent software package. The study focuses on a microchannel with a laminar steady flow and a bubble structure on one of the surfaces. The influence of velocity and gradient components on the flow near the boundary is investigated. The numerical solutions obtained in a 2D formulation were verified and compared with experimental data from the literature.
{"title":"Numerical Implementation of Boundary Conditions on Bubbles in a Microchannel with Stationary Laminar Flow","authors":"D. S. Gluzdov, E. Ya. Gatapova","doi":"10.1134/s1810232824030044","DOIUrl":"https://doi.org/10.1134/s1810232824030044","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The paper presents the implementation of a user-defined function (UDF) for the Navier boundary condition in the Fluent software package. The study focuses on a microchannel with a laminar steady flow and a bubble structure on one of the surfaces. The influence of velocity and gradient components on the flow near the boundary is investigated. The numerical solutions obtained in a 2D formulation were verified and compared with experimental data from the literature.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1134/s1810232824030123
Z. Li, W. Ao, L. Zhang, C. Liu, Y. Li, P. Dong, J. Tong
Abstract
In this study, a mathematical model of the dual suction compressor which can be applied to the household temperature and humidity independent control air conditioning system was established. The parameters of R410A were calculated with the help of REFPROP. The power consumptions of the dual suction compressor at different frequencies were calculated at different evaporation and condensing temperatures. Comparing with the experimental data, relative errors within (pm10)% between the simulated and experimental values of compressor power consumption occurred under various conditions, suggesting that the accuracy of the established energy consumption model met the requirements of engineering application. With the established model, the influence of different evaporation and condensing temperatures on the compressor power consumption and energy efficiency were simulated. The results showed that when keeping the evaporation temperature and condensing temperature of the LT side as a constant, the compressor power consumption decreased by 3.2% with each 1°C increment of the average evaporation temperature of the HT side. On the other hand, when the HT side evaporation temperature and condensing temperature was maintained as a constant, increased by 10% and the compressor power consumption decreased by 1.7% with each 1°C increment of the average LT side evaporation temperature. The verified model can be applied to guide the optimization of evaporation and condensing temperatures in the future practical application of dual suction compressor in temperature and humidity independent control air conditioning system.
{"title":"Establishment and Application of the Energy Consumption Model for a Novel Dual-Suction Compressor","authors":"Z. Li, W. Ao, L. Zhang, C. Liu, Y. Li, P. Dong, J. Tong","doi":"10.1134/s1810232824030123","DOIUrl":"https://doi.org/10.1134/s1810232824030123","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>In this study, a mathematical model of the dual suction compressor which can be applied to the household temperature and humidity independent control air conditioning system was established. The parameters of R410A were calculated with the help of REFPROP. The power consumptions of the dual suction compressor at different frequencies were calculated at different evaporation and condensing temperatures. Comparing with the experimental data, relative errors within <span>(pm10)</span>% between the simulated and experimental values of compressor power consumption occurred under various conditions, suggesting that the accuracy of the established energy consumption model met the requirements of engineering application. With the established model, the influence of different evaporation and condensing temperatures on the compressor power consumption and energy efficiency were simulated. The results showed that when keeping the evaporation temperature and condensing temperature of the LT side as a constant, the compressor power consumption decreased by 3.2% with each 1°C increment of the average evaporation temperature of the HT side. On the other hand, when the HT side evaporation temperature and condensing temperature was maintained as a constant, increased by 10% and the compressor power consumption decreased by 1.7% with each 1°C increment of the average LT side evaporation temperature. The verified model can be applied to guide the optimization of evaporation and condensing temperatures in the future practical application of dual suction compressor in temperature and humidity independent control air conditioning system.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1134/s1810232824030135
H. K. Mandal, D. K. Maiti, R. N. Jana
Abstract
An unsteady MHD-free convection heat-mass transfer from a viscous, incompressible fluid flow past an infinite vertical moving plate is studied here. The fluid is considered to be electrically conducting and chemically reacting. We consider three types of plate movements: uniform velocity, uniform acceleration, and periodic acceleration. Ramped as well as constant conditions at the plate for both temperature and concentration are considered. We obtain the exact solutions of the governing equations using the method of the Laplace transform technique. The impact of the type of thermal and concentration boundary condition (constant/ramped) at the plate as well as the kind of plate movement on the flow, heat and mass transfer characteristics, are presented and analyzed here. While doing so, we also consider the variation of our governing parameters: thermal and solutal Grashof numbers, magnetic field intensity, radiation ((R)), chemical reaction ((Kc)), Prandtl number and Schmidt numbers. It is observed that the presence of buoyancy and other forces close to the plate can be almost nullified due to the imposition of a strong transverse magnetic field. The viscous drag at the plate diminishes (and increases) with the increase of the strength of the applied magnetic field (and (R) and (Kc)). The rate of increment of skin friction with respect to time is more for the case of periodic oscillating plate movement. The magnitude of viscous drag is reported as more significant for the constant case compared to the ramped case.
摘要 本文研究了粘性不可压缩流体流过无限垂直移动板的非稳态 MHD 自由对流热质传递。流体被认为是导电和化学反应的。我们考虑了三种类型的板运动：匀速、匀加速和周期加速。考虑了板上温度和浓度的斜坡和恒定条件。我们使用拉普拉斯变换技术方法获得了控制方程的精确解。这里介绍并分析了板上热边界条件和浓度边界条件的类型（恒定/斜坡）以及板的运动类型对流动、传热和传质特性的影响。在分析过程中，我们还考虑了以下控制参数的变化：热和溶质格拉肖夫数、磁场强度、辐射（R）、化学反应（Kc）、普朗特数和施密特数。据观察，由于强横向磁场的存在，靠近板的浮力和其他力几乎可以被抵消。板上的粘性阻力随着外加磁场强度（以及 R 和 Kc）的增加而减小（或增加）。对于周期性摆动的平板运动，表皮摩擦力随时间的增加率更大。据报告，在恒定情况下，粘滞阻力的大小比在斜坡情况下更大。
{"title":"Unsteady MHD Free Convection in a Radiating Fluid Flow past a Vertically Time-Dependent Moving Plate with Ramped Double-Diffusive Condition","authors":"H. K. Mandal, D. K. Maiti, R. N. Jana","doi":"10.1134/s1810232824030135","DOIUrl":"https://doi.org/10.1134/s1810232824030135","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>An unsteady MHD-free convection heat-mass transfer from a viscous, incompressible fluid flow past an infinite vertical moving plate is studied here. The fluid is considered to be electrically conducting and chemically reacting. We consider three types of plate movements: uniform velocity, uniform acceleration, and periodic acceleration. Ramped as well as constant conditions at the plate for both temperature and concentration are considered. We obtain the exact solutions of the governing equations using the method of the Laplace transform technique. The impact of the type of thermal and concentration boundary condition (constant/ramped) at the plate as well as the kind of plate movement on the flow, heat and mass transfer characteristics, are presented and analyzed here. While doing so, we also consider the variation of our governing parameters: thermal and solutal Grashof numbers, magnetic field intensity, radiation (<span>(R)</span>), chemical reaction (<span>(Kc)</span>), Prandtl number and Schmidt numbers. It is observed that the presence of buoyancy and other forces close to the plate can be almost nullified due to the imposition of a strong transverse magnetic field. The viscous drag at the plate diminishes (and increases) with the increase of the strength of the applied magnetic field (and <span>(R)</span> and <span>(Kc)</span>). The rate of increment of skin friction with respect to time is more for the case of periodic oscillating plate movement. The magnitude of viscous drag is reported as more significant for the constant case compared to the ramped case.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1134/s181023282403007x
A. V. Kuznetsov, E. Yu. Shadrin
Abstract
A method for activated carbon production from pine nut shells by pyrolysis technology followed by steam-gas activation is considered. The process of thermal decomposition of sample in an inert environment was studied; the main stages of the process were identified; the residual mass was determined. The iodine adsorption activity, total pore volume, mass fraction of moisture, mass fraction of ash, and specific surface area were found. The experiments have shown that the production technology is efficient and the raw material is promising for activated carbon production.
{"title":"Experimental Study of Characteristics of Activated Carbon Produced from Pine Nut Shells by Pyrolysis Technology Followed by Steam-Gas Activation","authors":"A. V. Kuznetsov, E. Yu. Shadrin","doi":"10.1134/s181023282403007x","DOIUrl":"https://doi.org/10.1134/s181023282403007x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A method for activated carbon production from pine nut shells by pyrolysis technology followed by steam-gas activation is considered. The process of thermal decomposition of sample in an inert environment was studied; the main stages of the process were identified; the residual mass was determined. The iodine adsorption activity, total pore volume, mass fraction of moisture, mass fraction of ash, and specific surface area were found. The experiments have shown that the production technology is efficient and the raw material is promising for activated carbon production.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1134/s1810232824030032
I. K. Kabardin, N. I. Yavorsky, M. Kh. Pravdina, M. R. Gordienko, S. V. Kakaulin, K. S. Zubanov, G. V. Bakakin, V. G. Meledin
Abstract
Detailed experimental data on the kinematic characteristics of the flow in a vortex tube along its entire length are presented and analyzed. Experimental data obtained in a vortex tube with square cross-section of the working channel were compared at three values of the cold mass fraction: 0.4, 0.5, and 0.75 with the air expansion ratio in the apparatus of (pi=5). The behavior of standard deviations from the mean values of velocity components is analyzed. The noticeable peaks in the percentage of standard deviation from the longitudinal mean velocity component are observed in the area of the near wall flow temperature growth along the tube.
{"title":"LDA-Based Experimental Investigation of Velocity Pulsations in the Vortex Tube","authors":"I. K. Kabardin, N. I. Yavorsky, M. Kh. Pravdina, M. R. Gordienko, S. V. Kakaulin, K. S. Zubanov, G. V. Bakakin, V. G. Meledin","doi":"10.1134/s1810232824030032","DOIUrl":"https://doi.org/10.1134/s1810232824030032","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Detailed experimental data on the kinematic characteristics of the flow in a vortex tube along its entire length are presented and analyzed. Experimental data obtained in a vortex tube with square cross-section of the working channel were compared at three values of the cold mass fraction: 0.4, 0.5, and 0.75 with the air expansion ratio in the apparatus of <span>(pi=5)</span>. The behavior of standard deviations from the mean values of velocity components is analyzed. The noticeable peaks in the percentage of standard deviation from the longitudinal mean velocity component are observed in the area of the near wall flow temperature growth along the tube.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1134/s1810232824030172
A. V. Meleshkin, A. K. Sagidullin, S. Y. Misyura, V. S. Morozov, N. V. Marasanov, V. V. Glezer, M. Sh. Madygulov, M. T. Mito
Abstract
Experimental dependences (pressure-temperature) of phase equilibrium of hydrofluorocarbon R134a hydrate have been obtained in aqueous solution of the NaCl salt. The measurements were carried out at a salt concentration in water of 3.25 wt. % in the pressure range from 0.5 to 2.5 bar at temperatures varying from −3 to 10°C. In contrast with the pure water system, the presence of salt in the solution had an inhibitory effect. The equilibrium temperature on the equilibrium curve of R134a hydrate at a set pressure decreased by 12–25%, unlike the temperature for the system with pure water. Combined washing process followed by centrifugation decreased the mass concentration of the salt in the solution by 92% compared to the initial salt concentration.
{"title":"Phase Equilibrium for Hydrofluorocarbon R134a Hydrate. Hydrate-Based Desalination of NaCl Salt Solution","authors":"A. V. Meleshkin, A. K. Sagidullin, S. Y. Misyura, V. S. Morozov, N. V. Marasanov, V. V. Glezer, M. Sh. Madygulov, M. T. Mito","doi":"10.1134/s1810232824030172","DOIUrl":"https://doi.org/10.1134/s1810232824030172","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Experimental dependences (pressure-temperature) of phase equilibrium of hydrofluorocarbon R134a hydrate have been obtained in aqueous solution of the NaCl salt. The measurements were carried out at a salt concentration in water of 3.25 wt. % in the pressure range from 0.5 to 2.5 bar at temperatures varying from −3 to 10°C. In contrast with the pure water system, the presence of salt in the solution had an inhibitory effect. The equilibrium temperature on the equilibrium curve of R134a hydrate at a set pressure decreased by 12–25%, unlike the temperature for the system with pure water. Combined washing process followed by centrifugation decreased the mass concentration of the salt in the solution by 92% compared to the initial salt concentration.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1134/s1810232824030056
V. N. Grebenev, A. G. Demenkov, G. G. Chernykh
Abstract
The flow in the far planar momentumless turbulent wake in a passively stratified medium is investigated with the use of a mathematical model that includes, along with the averaged equation for transfer of the longitudinal component of velocity, the differential equations for balance of the turbulence energy (e), transfer of its dissipation rate (varepsilon), fluid density defect (langlerho_{1}rangle), shear turbulent stress (langle{u}'{v}'rangle), and vertical component of the mass flux vector (langle v'rho'rangle) in the far wake approximation. Algebraic truncation of the last two equations leads to the known gradient relations for the shear turbulent stress and the vertical component of the mass flux vector. It has been established that with a certain limitation on the values of the empirical constants of the mathematical model and with a time scale growth law consistent with the mathematical model, these relations are joint differential constraints of the model. It has been found that the local equilibrium approximation for the shear turbulent stress is equivalent to the equality to zero of the Poisson bracket for dimensionless values of the turbulent viscosity coefficient and the defect of the longitudinal velocity component. It has been obtained that the local equilibrium approximation for the vertical component of the mass flux vector is equivalent to the equality to zero of the Poisson bracket for dimensionless values of the turbulent diffusion coefficient and mean density. Results of numerical experiments illustrating the theoretical results are presented.
Abstract The flow in the far planarless momentumulent wake in a passively stratified medium is investigated with the use of a mathematical model that includes, along with the averageaged equation for transfer of longitudinal component of velocity, the differential equations for balance of the turbulence energy (e). Transfer of its dissipation rate (varepsilon), fluid density defect (langlerho_{1}rangle), shear turbulent stress ((e)、其耗散率的传递、流体密度缺陷、剪切湍流应力、远醒近似的质量通量矢量的垂直分量。通过对后两个方程进行代数截断，可以得到剪切湍流应力和质量通量矢量垂直分量的已知梯度关系。通过对数学模型经验常量值的一定限制以及与数学模型一致的时间尺度增长规律，可以确定这些关系是模型的联合微分约束条件。研究发现，剪切湍流应力的局部平衡近似值等同于湍流粘性系数和纵向速度分量缺陷的无量纲值的泊松括号等于零。对于湍流扩散系数和平均密度的无量纲值，质量通量矢量垂直分量的局部平衡近似等价于泊松括弧等于零。本文介绍了说明理论结果的数值实验结果。
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