Статті в журналах: "Modeling of heat flows"

1

Chen, C. J., W. Lin, Y. Haik, and K. D. Carlson. "Modeling of complex flows and heat transfer." Journal of Visualization 1, no. 1 (March 1998): 51–63. http://dx.doi.org/10.1007/bf03182474.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Statharas, John C., John G. Bartzis, and Demosthenes D. Papailiou. "Heat Transfer Modeling in Low Flows and Application to Reflood Heat Transfer." Nuclear Technology 92, no. 2 (November 1990): 248–59. http://dx.doi.org/10.13182/nt90-a34476.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Thakre, S. S., and J. B. Joshi. "CFD modeling of heat transfer in turbulent pipe flows." AIChE Journal 46, no. 9 (September 2000): 1798–812. http://dx.doi.org/10.1002/aic.690460909.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Peskova, E. E. "Numerical modeling of subsonic axisymmetric reacting gas flows." Journal of Physics: Conference Series 2057, no. 1 (October 1, 2021): 012071. http://dx.doi.org/10.1088/1742-6596/2057/1/012071.

Повний текст джерела

Анотація:

Abstract A numerical algorithm is developed and implemented for modelling axisymmetric subsonic reacting gas flows based on a previously created program for plane flows. The system of Navier-Stokes equations in the low Mach number limit is used as a mathematical model. Calculations of ethane pyrolysis for axisymmetric and plane flow of mixture at heat supply from the reactor’s walls are carried out. Through the interplay of the developed code and the code for plane flows it becomes possible to identify the geometric factor role at the presence of a large number of nonlinear physicochemical processes. We found that diffusion of synthesized molecular hydrogen mainly influences heat supply from the reactor’s walls to gas and pyrolysis products distribution along its length.

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Keyhani, M., and R. A. Polehn. "Finite Difference Modeling of Anisotropic Flows." Journal of Heat Transfer 117, no. 2 (May 1, 1995): 458–64. http://dx.doi.org/10.1115/1.2822544.

Повний текст джерела

Анотація:

A modification to the finite difference equations is proposed in modeling multidimensional flows in an anisotropic material. The method is compared to the control volume version of the Taylor expansion and the finite element formulation derived from the Galerkin weak statement. For the same number of nodes, the proposed finite difference formulation approaches the accuracy of the finite element method. For the two-dimensional case, the effect on accuracy and solution stability is approximately the same as quadrupling the number of nodes for the Taylor expansion with only a proportionately small increase in the number of computations. Excellent comparisons are made with a new limiting case exact solution modeling anisotropic heat conduction and a transient, anisotropic conduction experiment from the literature.

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Wood, Brian D., Xiaoliang He, and Sourabh V. Apte. "Modeling Turbulent Flows in Porous Media." Annual Review of Fluid Mechanics 52, no. 1 (January 5, 2020): 171–203. http://dx.doi.org/10.1146/annurev-fluid-010719-060317.

Повний текст джерела

Анотація:

Turbulent flows in porous media occur in a wide variety of applications, from catalysis in packed beds to heat exchange in nuclear reactor vessels. In this review, we summarize the current state of the literature on methods to model such flows. We focus on a range of Reynolds numbers, covering the inertial regime through the asymptotic turbulent regime. The review emphasizes both numerical modeling and the development of averaged (spatially filtered) balances over representative volumes of media. For modeling the pore scale, we examine the recent literature on Reynolds-averaged Navier–Stokes (RANS) models, large-eddy simulation (LES) models, and direct numerical simulations (DNS). We focus on the role of DNS and discuss how spatially averaged models might be closed using data computed from DNS simulations. A Darcy–Forchheimer-type law is derived, and a prior computation of the permeability and Forchheimer coefficient is presented and compared with existing data.

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Hasan, A. R., and C. S. Kabir. "Modeling two-phase fluid and heat flows in geothermal wells." Journal of Petroleum Science and Engineering 71, no. 1-2 (March 2010): 77–86. http://dx.doi.org/10.1016/j.petrol.2010.01.008.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Hachem, E., G. Jannoun, J. Veysset, M. Henri, R. Pierrot, I. Poitrault, E. Massoni, and T. Coupez. "Modeling of heat transfer and turbulent flows inside industrial furnaces." Simulation Modelling Practice and Theory 30 (January 2013): 35–53. http://dx.doi.org/10.1016/j.simpat.2012.07.013.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Yao, Xiaobo, and André W. Marshall. "Quantitative Salt-Water Modeling of Fire-Induced Flows for Convective Heat Transfer Model Development." Journal of Heat Transfer 129, no. 10 (February 23, 2007): 1373–83. http://dx.doi.org/10.1115/1.2754943.

Повний текст джерела

Анотація:

This research provides a detailed analysis of convective heat transfer in ceiling jets by using a quantitative salt-water modeling technique. The methodology of quantitative salt-water modeling builds on the analogy between salt-water flow and fire induced flow, which has been successfully used in the qualitative analysis of fires. Planar laser induced fluorescence and laser doppler velocimetry have been implemented to measure the dimensionless density difference and velocity in salt-water plumes. The quantitative salt-water modeling technique has been validated through comparisons of appropriately scaled salt-water measurements, fire measurements, and theory. This analogy has been exploited to develop an engineering heat transfer model for predicting heat transfer in impinging fire plumes using salt-water measurements along with the adiabatic wall modeling concept. Combining quantitative salt-water modeling and adiabatic wall modeling concepts introduces new opportunities for studying heat transfer issues in basic and complex fire induced flow configurations.

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Zaichik, L. I., V. A. Pershukov, M. V. Kozelev, and A. A. Vinberg. "Modeling of dynamics, heat transfer, and combustion in two-phase turbulent flows: 2. Flows with heat transfer and combustion." Experimental Thermal and Fluid Science 15, no. 4 (November 1997): 311–22. http://dx.doi.org/10.1016/s0894-1777(96)00201-4.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Zaichik, L. I., V. A. Pershukov, M. V. Kozelev, and A. A. Vinberg. "Modeling of dynamics, heat transfer, and combustion in two-phase turbulent flows: 1. Isothermal flows." Experimental Thermal and Fluid Science 15, no. 4 (November 1997): 291–310. http://dx.doi.org/10.1016/s0894-1777(97)00009-5.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

12

Tsui, Yeng-Yung, Shi-Wen Lin, and Kuen-Je Ding. "Modeling of Heat Transfer Across the Interface in Two-Fluid Flows." Numerical Heat Transfer, Part B: Fundamentals 66, no. 2 (June 23, 2014): 162–80. http://dx.doi.org/10.1080/10407790.2014.894450.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

13

Yeoh, G. H., and J. Y. Tu. "Thermal-hydrodynamic modeling of bubbly flows with heat and mass transfer." AIChE Journal 51, no. 1 (2004): 8–27. http://dx.doi.org/10.1002/aic.10297.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

14

Nagrani, Pranay P., Federico Municchi, Amy M. Marconnet, and Ivan C. Christov. "Two-fluid modeling of heat transfer in flows of dense suspensions." International Journal of Heat and Mass Transfer 183 (February 2022): 122068. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2021.122068.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

15

Hamidi, K., T. Rezoug, and S. Poncet. "Numerical Modeling of Heat Transfer in Taylor-Couette-Poiseuille Systems." Defect and Diffusion Forum 390 (January 2019): 125–32. http://dx.doi.org/10.4028/www.scientific.net/ddf.390.125.

Повний текст джерела

Анотація:

The purpose of this work is to model turbulent Taylor-Couette-Poiseuille flows submitted to a temperature gradient. These flows are relevant in many industrial applications including rotating machineries and more especially for the effective cooling of electric motors. Several turbulence closures (k-ω SST, RSM and LES) are first compared in the isothermal case and validated against the reliable experimental data of Escudier and Gouldson [1]. A detailed analysis of the coherent structures within the boundary layers is proposed. The model offering the best compromise between computational cost and accuracy is then used to perform more computations in the configuration with a temperature gradient considered by Kuosa et al. [2]. In their system, the air flow enters the rotor-stator cavity radially. Correlations for the average Nusselt numbers along the rotor and stator as a function of the control parameters (rotation rate, air flow rate, Prandtl number) are provided and compared with data available in the literature [3].

Стилі APA, Harvard, Vancouver, ISO та ін.

16

Chung, Yongmann M., and Paul G. Tucker. "Assessment of Periodic Flow Assumption for Unsteady Heat Transfer in Grooved Channels." Journal of Heat Transfer 126, no. 6 (December 1, 2004): 1044–47. http://dx.doi.org/10.1115/1.1833371.

Повний текст джерела

Анотація:

Numerical studies of unsteady heat transfer in grooved channel flows are made. The flows are of special relevance to electronic systems. Predictions suggest a commonly used periodic flow assumption (for modeling rows of similar electronic components) may not be valid over a significant system extent. It is found that the downstream flow development is strongly dependent on geometry.

Стилі APA, Harvard, Vancouver, ISO та ін.

17

Pinson, F., O. Gregoire, M. Quintard, M. Prat, and O. Simonin. "Modeling of turbulent heat transfer and thermal dispersion for flows in flat plate heat exchangers." International Journal of Heat and Mass Transfer 50, no. 7-8 (April 2007): 1500–1515. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2006.08.033.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

18

Fairuzov, Yuri V., and Hector Arvizu. "Numerical Solution for Transient Conjugate Two-Phase Heat Transfer With Heat Generation in the Pipe Wall." Journal of Heat Transfer 124, no. 6 (December 1, 2002): 1213–18. http://dx.doi.org/10.1115/1.1470170.

Повний текст джерела

Анотація:

A method developed earlier for modeling conjugate two-phase heat transfer in flashing flows was used to obtain a numerical solution for transient boiling flow in heated pipes or channels. Two criteria of applicability of the solution obtained were proposed and numerically tested using a more rigorous model, which accounts for the effects of heat conduction with heat generation in the wall and forced convective boiling. The solution obtained provides a simple and reliable alternative to more rigorous methods for modeling transient two-phase flow in heated channels when the material of the wall bounding the flow has a high thermal conductivity and the wall superheat is small.

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Askarova, A. S., S. A. Bolegenova, S. A. Bolegenova, V. Yu Maximov, and M. T. Beketayeva. "Modeling of Heat Mass Transfer in High-Temperature Reacting Flows with Combustion." High Temperature 56, no. 5 (September 2018): 738–43. http://dx.doi.org/10.1134/s0018151x1805005x.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

20

Cooper, Phillip S., James W. Leach, and Joseph N. Sinodis. "Modeling Fluid Flows and Heat Transfer in Industrial Processes Using Gothic Software." Energy Engineering 101, no. 5 (September 2004): 7–31. http://dx.doi.org/10.1080/01998590409509276.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

21

Li, J., G. M. Campbell, and A. S. Mujumdar. "Discrete Modeling and Suggested Measurement of Heat Transfer in Gas–Solids Flows." Drying Technology 21, no. 6 (January 7, 2003): 979–94. http://dx.doi.org/10.1081/drt-120021851.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Choi, Yun-Ho. "Numerical modeling of heat and mass diffusion in compressible low speed flows." KSME International Journal 12, no. 5 (September 1998): 988–98. http://dx.doi.org/10.1007/bf02945566.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

23

Muto, Daiki, Yu Daimon, Hideyo Negishi, and Taro Shimizu. "Wall modeling of turbulent methane/oxygen reacting flows for predicting heat transfer." International Journal of Heat and Fluid Flow 87 (February 2021): 108755. http://dx.doi.org/10.1016/j.ijheatfluidflow.2020.108755.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

24

Zhang, Yudong, Aiguo Xu, Feng Chen, Chuandong Lin, and Zon-Han Wei. "Non-equilibrium characteristics of mass and heat transfers in the slip flow." AIP Advances 12, no. 3 (March 1, 2022): 035347. http://dx.doi.org/10.1063/5.0086400.

Повний текст джерела

Анотація:

Slip flow is a common phenomenon in micro-/nano-electromechanical systems. It is well known that the mass and heat transfers in slip flow show many unique behaviors, such as the velocity slip and temperature jump near the wall. However, the kinetic understanding of slip flow is still an open problem. This paper first clarifies that the Thermodynamic Non-Equilibrium (TNE) flows can be roughly classified into two categories: near-wall TNE flows and TNE flows away from the wall. The origins of TNE in the two cases are significantly different. For the former, the TNE mainly results from the fluid–wall interaction; for the latter, the TNE is primarily due to the considerable (local) thermodynamic relaxation time. Therefore, the kinetic modeling methods for the two kinds of TNE flows are significantly different. Based on the Discrete Boltzmann Modeling (DBM) method, the non-equilibrium characteristics of mass and heat transfers in slip flow are demonstrated and investigated. The method is solidly verified by comparing with analytic solutions and experimental data. In pressure-driven flow, the DBM results are consistent with experimental data for the Knudsen number up to 0.5. It is verified that, in the slip flow regime, the linear constitutive relations with standard viscous or heat conduction coefficients are no longer applicable near the wall. For the Knudsen layer problem, it is interesting to find that a heat flux (viscous stress) component in the velocity (temperature) Knudsen layer approximates a hyperbolic sinusoidal distribution. The findings enrich the insights into the non-equilibrium characteristics of mass and heat transfers at micro-/nano-scales.

Стилі APA, Harvard, Vancouver, ISO та ін.

25

Ulybyshev, S. K., and B. A. Staroverov. "Imitation model of heat flows distribution in building heating control system." Vestnik IGEU, no. 2 (April 30, 2021): 70–79. http://dx.doi.org/10.17588/2072-2672.2021.2.070-079.

Повний текст джерела

Анотація:

Implementation of automatic heating control systems allows us to reduce heat consumption by 10% in residential areas and 40% in office and educational buildings. Currently, there are heating control systems, however, they are applied only to a single-level two-pipe heating system. Development of an imitation model of heat flows redistribution is necessary to synthesize the system of interconnected dynamic heating control of a building. Unlike existing solutions, this research work considers the problem of unbalanced heat flow in a multi-level hierarchical heating system. Calculation of convective heat transfer in the room assumes that the air temperature at any given time is the same throughout the entire room. When we determine heat transfer through walling, it is assumed that the walling or its part has the same temperature of the planes perpendicular to the direction of air flow. In this case, the heat transfer process is described by a one-dimensional heat transfer equation. The developed model of heating control systems allows us to connect the automatic control modules, change control algorithms at the compilation stage and in the system state during the simulation process. In comparison with possible analogue models based on AnyLogic or ANSYS modeling systems, the presented model is the model of controlled object. It is easily combined with models of automatic control units and considers the problem of imbalance of heat flows. An example of the functional scheme of the local temperature control system around one battery is considered. Implementation of developed imitation model makes it possible to ensure a new level of quality control of technological processes of production and consumption of power energy resources by using modern information technologies and synthesizing a system of interconnected dynamic heating control. Possibilities of such modeling are focused on development of the uninterrupted and high-quality heat supply system, maintaining energy-efficient operating modes, as well as actual economic effect. The model under consideration allows us to simulate redistribution of heat flows in different operating modes of the heating system.

Стилі APA, Harvard, Vancouver, ISO та ін.

26

Merala, Raymond, Mont Hubbard, and Takashi Miyano. "Modeling and Simulation of a Supercharger." Journal of Dynamic Systems, Measurement, and Control 110, no. 3 (September 1, 1988): 316–23. http://dx.doi.org/10.1115/1.3152688.

Повний текст джерела

Анотація:

A dynamic model is developed for simulating and predicting performance for superchargers of relatively arbitrary geometric configuration. A thermodynamic control volume approach and bond graph models are used to derive continuity and energy equations linking the various control volumes. Bond graphs also serve to study and understand the causal implications of laws governing flows between control volumes and system dynamics. Heat transfer is neglected. Simulation outputs include time histories of pressure, temperature, mass, and energy associated with each control volume, time histories of the various flows in the supercharger, and overall volumetric efficiency. Volumetric efficiencies are predicted over a wide range of speed/pressure ratio combinations and are within three percent of experimentally measured values. The simulation is used to investigate the sensitivity of supercharger performance to several key design parameters, including rotor-rotor separation, and rotor-housing and side plate clearance distances.

Стилі APA, Harvard, Vancouver, ISO та ін.

27

Alessandri, Angelo, Patrizia Bagnerini, Roberto Cianci, and Roberto Revetria. "Modeling and Estimation of Thermal Flows Based on Transport and Balance Equations." Advances in Mathematical Physics 2020 (February 1, 2020): 1–10. http://dx.doi.org/10.1155/2020/9621308.

Повний текст джерела

Анотація:

Heat transfer in counterflow heat exchangers is modeled by using transport and balance equations with the temperatures of cold fluid, hot fluid, and metal pipe as state variables distributed along the entire pipe length. Using such models, boundary value problems can be solved to estimate the temperatures over all the length by means of measurements taken only at the boundaries. Conditions for the stability of the estimation error given by the difference between the temperatures and their estimates are established by using a Lyapunov approach. Toward this end, a method to construct nonlinear Lyapunov functionals is addressed by relying on a polynomial diagonal structure. This stability analysis is extended in case of the presence of bounded modeling uncertainty. The theoretical findings are illustrated with numerical results, which show the effectiveness of the proposed approach.

Стилі APA, Harvard, Vancouver, ISO та ін.

28

Nagano, Y., and C. Kim. "A Two-Equation Model for Heat Transport in Wall Turbulent Shear Flows." Journal of Heat Transfer 110, no. 3 (August 1, 1988): 583–89. http://dx.doi.org/10.1115/1.3250532.

Повний текст джерела

Анотація:

A new proposal for closing the energy equation is presented at the two-equation level of turbulence modeling. The eddy diffusivity concept is used in modeling. However, just as the eddy viscosity is determined from solutions of the k and ε equations, so the eddy diffusivity for heat is given as functions of temperature variance t2, and the dissipation rate of temperature fluctuations εt, together with k and ε. Thus, the proposed model does not require any questionable assumptions for the “turbulent Prandtl number.” Modeled forms of the t2 and εt equations are developed to account for the physical effects of molecular Prandtl number and near-wall turbulence. The model is tested by application to a flat-plate boundary layer, the thermal entrance region of a pipe, and the turbulent heat transfer in fluids over a wide range of the Prandtl number. Agreement with the experiment is generally very satisfactory.

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Shahbakhsh, Arash, and Astrid Nieße. "Modeling multimodal energy systems." at - Automatisierungstechnik 67, no. 11 (November 26, 2019): 893–903. http://dx.doi.org/10.1515/auto-2019-0063.

Повний текст джерела

Анотація:

Abstract Information and communication technology (ICT) and the technology of coupling points including power-to-gas (PtG), power-to-heat (PtH) and combined heat and power (CHP) reshape future energy systems fundamentally. To study the resulting multimodal smart energy system, a proposed method is to separate the behavior of the component layer from the control layer. The component layer includes pipelines, power-lines, generators, loads, coupling points and generally all components through which energy flows. In the work at hand, a model is presented to analyze the operational behavior of the component layer. The modeling problem is formulated as state and phase transition functions, which present the external commands and internal dynamics of system. Phase transition functions are approximated by ordinary differential equations, which are solved with integral methods. State transition functions are nonlinear algebraic functions, which are solved numerically and iteratively with a modified Newton–Raphson method. In a proof-of-concept case study, a scenario shows the expected multi-sector effects based on evaluated models.

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Мартыненко, С. И. "On the approximation error in the problems of conjugate convective heat transfer." Numerical Methods and Programming (Vychislitel'nye Metody i Programmirovanie), no. 4 (September 10, 2019): 438–43. http://dx.doi.org/10.26089/nummet.v20r438.

Повний текст джерела

Анотація:

Рассмотрено влияние малых возмущений границы области на погрешность аппроксимации модельной краевой задачи. Показано, что игнорирование малых возмущений границы приводит к дополнительной погрешности аппроксимации исходной дифференциальной задачи, не связанной с шагом сетки. Полученные результаты представляют интерес для математического моделирования сопряженного теплообмена, моделирования течений с поверхностными химическими реакциями и других приложений, связанных с течениями рабочих сред вблизи шероховатых поверхностей. The effects of small boundary perturbation on the approximation error for a model boundary value problem are considered. It is shown that the ignorance of small perturbations of the boundary leads to an additional approximation error in the original differential problem. This error is independent of mesh size. The obtained results are of interest for the mathematical modeling of conjugate heat transfer, the modeling of flows with surface chemical reactions and other applications related to fluid flows near rough surfaces.

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Meziou, Amine, Zurwa Khan, Taoufik Wassar, Matthew A. Franchek, Reza Tafreshi, and Karolos Grigoriadis. "Dynamic Modeling of Two-Phase Gas/Liquid Flow in Pipelines." SPE Journal 24, no. 05 (April 22, 2019): 2239–63. http://dx.doi.org/10.2118/194213-pa.

Повний текст джерела

Анотація:

Summary Presented is a reduced–order thermal fluid dynamic model for gas/liquid two–phase flow in pipelines. Specifically, a two–phase–flow thermal model is coupled with a two–phase–flow hydraulics model to estimate the gas and liquid properties at each pressure and temperature condition. The proposed thermal model estimates the heat–transfer coefficient for different flow patterns observed in two–phase flow. For distributed flows, where the two phases are well–mixed, a weight–based averaging is used to estimate the equivalent fluid thermal properties and the overall heat–transfer coefficient. Conversely, for segregated flows, where the two phases are separated by a distinct interface, the overall heat–transfer coefficient is dependent on the liquid holdup and pressure drop estimated by the fluid model. Intermittent flows are considered as a combination of distributed and segregated flow. The integrated model is developed by dividing the pipeline into segments. Equivalent fluid properties are identified for each segment to schedule the coefficients of a modal approximation of the transient single–phase–flow pipeline–distributed–parameter model to obtain dynamic pressure and flow rate, which are used to estimate the transient temperature response. The resulting model enables a computationally efficient estimation of the pipeline–mixture pressure, temperature, two–phase–flow pattern, and liquid holdup. Such a model has utility for flow–assurance studies and real–time flow–condition monitoring. A sensitivity analysis is presented to estimate the effect of model parameters on the pipeline–mixture dynamic response. The model predictions of mixture pressure and temperature are compared with an experimental data set and OLGA (2014) simulations to assess model accuracy.

Стилі APA, Harvard, Vancouver, ISO та ін.

32

Farakhov, T. M., and A. G. Laptev. "Modeling of temperature profiles and efficiency of heat transfer equipment with intensifiers." Power engineering: research, equipment, technology 22, no. 2 (May 15, 2020): 12–18. http://dx.doi.org/10.30724/1998-9903-2020-22-1-12-18.

Повний текст джерела

Анотація:

The problem of determination of temperature fields in the flow and efficiency of heat exchangers with intensification by metal chaotic packings is considered. Results of experimental studies of the heating of industrial oil with hot water in a "pipe-in-pipe" heat exchanger, where a chaotic packing of nominal size 6 mm is placed in the internal pipe, are presented. The packing, due to turbulence in the flow of oil, provides transition from the laminar to the turbulent regime and a significant increase in heat transfer coefficient (by 15-20 times). For calculating temperature profiles in channels, a cell model of the flow structure is written, where the main parameters are thermal number of transfer units and number of complete mixing cells. Expressions are given for calculating these parameters in pipes with chaotic packings. Results of calculating temperature profiles for various flowrates of the heated oil are presented and satisfactory agreement with experimental data is shown. The calculation of temperature fields makes it possible to take into account a change in thermophysical properties of flows along the length of the channels, which is especially important for hydrocarbon mixtures with high viscosity and large Prandtl numbers. The presented mathematical model allows to take into account the structure of heat carrier flows in apparatus with intensifiers and to calculate thermal efficiency of the processes of heating and cooling the media.

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Narain, A. "Modeling of Interfacial Shear for Gas Liquid Flows in Annular Film Condensation." Journal of Applied Mechanics 63, no. 2 (June 1, 1996): 529–38. http://dx.doi.org/10.1115/1.2788900.

Повний текст джерела

Анотація:

Internal flow of pure vapor experiencing film condensation on the walls of a straight horizontal duct is studied. The commonly occurring annular case of turbulent (or laminar) vapor flow in the core and laminar flow of the liquid condensate—with or without waves on the interface—is emphasized. We present a new methodology which models interfacial shear with the help of theory, computations, and reliable experimental data on heat transfer rates. The theory—at the point of onset of condensation—deals with issues of asymptotic form of interfacial shear, nonuniqueness of solutions, and selection of the physically admissible solution by a stability type criteria. Other details of the flow are predicted with the help of the proposed modeling approach. These predictions are shown to be in agreement with relevant experimental data. The trends for film thickness, heat transfer rates, and pressure drops are also made available in the form of power-law correlations.

Стилі APA, Harvard, Vancouver, ISO та ін.

34

Akin, Serhat. "Mathematical Modeling of Steam Assisted Gravity Drainage." SPE Reservoir Evaluation & Engineering 8, no. 05 (October 1, 2005): 372–76. http://dx.doi.org/10.2118/86963-pa.

Повний текст джерела

Анотація:

Summary A mathematical model for gravity drainage in heavy-oil reservoirs and tar sands during steam injection in linear geometry is proposed. The mathematical model is based on the experimental observations that the steam-zone shape is an inverted triangle with the vertex fixed at the bottom production well. Both temperature and asphaltene content dependence on the viscosity of the drained heavy oil are considered. The developed model has been validated with experimental data presented in the literature. The heavy-oil production rate conforms well to previously published data covering a wide range of heavy oils and sands for gravity drainage. Introduction Gravity drainage of heavy oils is of considerable interest to the oil industry. Because heavy oils are very viscous and, thus, almost immobile, a recovery mechanism is required that lowers the viscosity of the material to the point at which it can flow easily to a production well. Conventional thermal processes, such as cyclic steam injection and steam-assisted gravity drainage(SAGD), are based on thermal viscosity reduction. Cyclic steam injection incorporates a drive enhancement from thermal expansion. On the other hand, SAGD is based on horizontal wells and maximizing the use of gravity forces. In the ideal SAGD process, a growing steam chamber forms around the horizontal injector, and steam flows continuously to the perimeter of the chamber, where it condenses and heats the surrounding oil. Effective initial heating of the cold oil is important for the formation of the steam chamber in gravity-drainage processes. Heat is transferred by conduction, by convection, and by the latent heat of steam. The heated oil drains to a horizontal production well located at the base of the reservoir just below the injection well. Based on the aforementioned concepts, Butler et al. derived Eq. 1 assuming that the steam pressure is constant in the steam chamber, that only steam flows in the steam chamber, that oil saturation is residual, and that heat transfer ahead of the steam chamber to cold oil is only by conduction. One physical analogy of this process is that of a reservoir in which an electric heating element is placed horizontally above a parallel horizontal producing well.

Стилі APA, Harvard, Vancouver, ISO та ін.

35

Loshkarev, V. A. "Diagnostics and Modeling of Heat Transfer in High-Enthalpy Gas Flows with Local Heat Sources and Sinks." Heat Transfer Research 33, no. 7-8 (2002): 11. http://dx.doi.org/10.1615/heattransres.v33.i7-8.120.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

36

Obukhov, A. G., and L. I. Maksimov. "Calculation of gas flow rates in concentrated fire vortices." Oil and Gas Studies, no. 5 (November 17, 2019): 108–14. http://dx.doi.org/10.31660/0445-0108-2019-5-108-114.

Повний текст джерела

Анотація:

The article presents the results of numerical simulation of the generation of free fire vortices in the laboratory without the use of special twisting devices. A. Yu. Varaksin, the corresponding member of the Russian Academy of Sciences, in his experimental studies has described the principal possibility of physical modeling of the occurrence of concentrated fire vortices. In the model of a compressible continuous medium for the complete system of Navier — Stokes equations, an initial-boundary value problem has been proposed that describes complex three-dimensional unsteady flows of a viscous compressible heat-conducting gas in ascending swirling heat flows. We has constructed approximate solutions of the complete Navier — Stokes system of equations and has determined velocity characteristics of threedimensional unsteady gas flows initiated by local heating of the underlying surface by nineteen heat sources, using explicit difference schemes and the proposed initial-boundary conditions.

Стилі APA, Harvard, Vancouver, ISO та ін.

37

Kaul, Upender K., and Raymond P. Shreeve. "Full Viscous Modeling in Generalized Coordinates of Heat Conducting Flows in Rotating Systems." Journal of Thermophysics and Heat Transfer 11, no. 2 (April 1997): 320. http://dx.doi.org/10.2514/2.6245.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

38

Nagano, Y., H. Hattori, and K. Abe. "Modeling the turbulent heat and momentum transfer in flows under different thermal conditions." Fluid Dynamics Research 20, no. 1-6 (February 15, 1997): 127–42. http://dx.doi.org/10.1016/s0169-5983(96)00049-4.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

39

YAMAMOTO, Atsushi, Shigeo KIMURA, Nobuyoshi KOMATSU, Takahiro KIWATA, Takaaki KONO, and Masahiro GOTO. "1313 Numerical Modeling of the Heat Exchanger Performance placed in Running Water Flows." Proceedings of Conference of Hokuriku-Shinetsu Branch 2016.53 (2016): _1313–1_—_1313–5_. http://dx.doi.org/10.1299/jsmehs.2016.53._1313-1_.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

40

Kaul, Upender K., and Raymond P. Shreeve. "Full viscous modeling in generalized coordinates of heat conducting flows in rotating systems." Journal of Thermophysics and Heat Transfer 10, no. 4 (October 1996): 621–26. http://dx.doi.org/10.2514/3.838.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

41

Franca, Fernando A., Antonio C. Bannwart, Ricardo M. T. Camargo, and Marcelo A. L. Gonçalves. "Mechanistic Modeling of the Convective Heat Transfer Coefficient in Gas-Liquid Intermittent Flows." Heat Transfer Engineering 29, no. 12 (December 2008): 984–98. http://dx.doi.org/10.1080/01457630802241091.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

42

ITAZU, Yoshihiro, and Yasutaka NAGANO. "RNG Modeling of Turbulent Heat Flux and Its Application to Wall Shear Flows." JSME International Journal Series B 41, no. 3 (1998): 657–65. http://dx.doi.org/10.1299/jsmeb.41.657.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

43

Dombard, J., B. Leveugle, L. Selle, J. Reveillon, T. Poinsot, and Y. D’Angelo. "Modeling heat transfer in dilute two-phase flows using the Mesoscopic Eulerian Formalism." International Journal of Heat and Mass Transfer 55, no. 5-6 (February 2012): 1486–95. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2011.10.050.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

44

Johnson, Evan F., İlker Tarı, and Derek Baker. "Modeling heat exchangers with an open source DEM-based code for granular flows." Solar Energy 228 (November 2021): 374–86. http://dx.doi.org/10.1016/j.solener.2021.09.067.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

45

Rassamakin, B. M., V. A. Rogachyov, V. I. Khominich, Yu V. Petrov, and S. M. Khayrnasov. "Experimental modeling of heat modes of small space vehicles and their external heat flows. I. TVK-2.5 heat vacuum plant." Kosmìčna nauka ì tehnologìâ 8, no. 1 (January 30, 2002): 37–41. http://dx.doi.org/10.15407/knit2002.01.037.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Mehdi-Nejad, V., J. Mostaghimi, and S. Chandra. "Modelling heat transfer in two-fluid interfacial flows." International Journal for Numerical Methods in Engineering 61, no. 7 (September 28, 2004): 1028–48. http://dx.doi.org/10.1002/nme.1101.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

47

Hanjalic´, K., I. Hadzˇic´, and S. Jakirlic´. "Modeling Turbulent Wall Flows Subjected to Strong Pressure Variations." Journal of Fluids Engineering 121, no. 1 (March 1, 1999): 57–64. http://dx.doi.org/10.1115/1.2822011.

Повний текст джерела

Анотація:

Mean pressure gradient affects the turbulence mainly through the modulation of the mean rate of strain. Modification of the turbulence structure feeds, in turn, back into the mean flow. Particularly affected is the near wall region (including the viscous sublayer) where the pressure gradient invalidates the conventional boundary-layer “equilibrium” assumptions and inner-wall scaling. Accurate predictions of such flows require application of advanced turbulence closures, preferably at the differential second-moment level with integration up to the wall. This paper aims at demonstrating the potential usefulness of such a model to engineers by revisiting some of the recent experimental and DNS results and by presenting a series of computations relevant to low-speed external aerodynamics. Several attached and separated flows, subjected to strong adverse and favorable pressure gradient, as well as to periodic alternation of the pressure gradient sign, all computed with a low-Re-number second-moment closure, display good agreement with experimental and DNS data. It is argued that models of this kind (in full or a truncated form) may serve both for steady or transient Reynolds-Averaged Navier-Stokes (RANS, TRANS) computations of a variety of industrial and aeronautical flows, particularly if transition phenomena, wall friction, and heat transfer are in focus.

Стилі APA, Harvard, Vancouver, ISO та ін.

48

Spall, Robert E., Eugen Nisipeanu, and Adam Richards. "Assessment of a Second-Moment Closure Model for Strongly Heated Internal Gas Flows." Journal of Heat Transfer 129, no. 12 (April 10, 2007): 1719–22. http://dx.doi.org/10.1115/1.2768098.

Повний текст джерела

Анотація:

Both low- and high-Reynolds-number versions of the stress-ω model of Wilcox (Turbulence Modeling for CFD, 2nd ed., DCW Industries, Inc.) were used to predict velocity and heat transfer data in a high-heat-flux cylindrical tube for which fluid properties varied strongly with temperature. The results indicate that for accurate heat transfer calculations under the conditions considered in this study, inclusion of low-Reynolds-number viscous corrections to the model are essential. The failure of the high-Reynolds-number model to accurately predict the wall temperature was attributed to an overprediction of the near-wall velocity.

Стилі APA, Harvard, Vancouver, ISO та ін.

49

Taler, Dawid, Jan Taler, and Katarzyna Wrona. "Transient behavior of a plate-fin-and-tube heat exchanger taking into account different heat transfer coefficients on the individual tube rows." E3S Web of Conferences 137 (2019): 01036. http://dx.doi.org/10.1051/e3sconf/201913701036.

Повний текст джерела

Анотація:

Plate-fin and tube heat exchangers (PFTHE) are made of round, elliptical, oval or flat tubes to which continuous fins ( lamellas) are attached. Liquid flows inside the tubes and gas flows outside the tubes perpendicularly to their axes and parallel to the surface of continuous fins. Experimental studies of multi-row plate-fin and tube heat exchangers show that the highest average heat transfer coefficient on the air side occurs in the first row of tubes when the air velocity in front of the exchanger is less than approximately 3.5 m/s when a Reynolds number based on an equivalent hydraulic diameter equal to the distance between tube rows in the direction of air flow is less than 10,000. In the subsequent rows of tubes up to about the fourth row the heat transfer coefficient decreases. In the fifth and further rows, it can, that the heat transfer coefficient is equal in each tube row. It is necessary to find the relationships for the air-side Nusselt number on each tube row to design a PFTHE with the appropriate number of tube rows. The air-side Nusselt number correlations can be determined experimentally or by CFD modeling (Computational and Fluid Dynamics). The paper presents a new mathematical model of the transient operation of PFTHE, considering that the Nusselt numbers on the air side of individual tube rows are different. The heat transfer coefficient on an analyzed tube row was determined from the equality condition of mass- average air temperature differences on a given tube row determined using the analytical formula and CFD modeling. The results of numerical modeling were compared with the results of the experiments.

Стилі APA, Harvard, Vancouver, ISO та ін.

50

Tarasov, George, Konstantin Gyrnik, and Denis Leontev. "Parallel Algorithm for Modeling of Dynamic Processes in Porous Media." Advanced Materials Research 1040 (September 2014): 559–64. http://dx.doi.org/10.4028/www.scientific.net/amr.1040.559.

Повний текст джерела

Анотація:

Parallel algorithm for modeling the unsteady 2D gas flows through a porous media with energy sources is presented. A mathematical model of dynamic processes in porous heat-evolutional object is mentioned briefly. The structure of sequential algorithm and its parallel version is described in details. The performance and efficiency of parallel algorithm and its realization using OpenMP technology is evaluated.

Стилі APA, Harvard, Vancouver, ISO та ін.

Статті в журналах з теми "Modeling of heat flows"

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями