Artigos de revistas: "Heat exchangers Fluid dynamics"

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Dawood Jumaah, Itimad, Senaa Kh. Ali e Anees A. Khadom. "Evaluation Analysis of Double Coil Heat Exchanger for Heat Transfer Enhancement". Diyala Journal of Engineering Sciences 14, n.º 1 (15 de março de 2021): 96–107. http://dx.doi.org/10.24237/djes.2021.14109.

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In order to maximize the thermal efficiency of shell and coil heat exchangers, substantial research has been done and geometrical modification is one way to improve the exchange of thermal energy between two or more fluids. One of the peculiar features of coiled geometry is that the temperature distribution is highly variable along the circumferential section due to the centrifugal force induced in the fluid. Moreover, most researchers are concentrated on using a shell and single helical coil heat exchanger to enhance the heat transfer rate and thermal efficiency at different operating parameters. Therefore, the aim of this study is to investigate temperature variation ((T-1, T-2, T-3 and T-4) across a shell and single/double coil heat exchanger at different coil pitches, hot water flow rate, and cold-water flow rate along the outer surface of the coil using experimental and numerical analysis. For single and double coil heat exchangers, Computational Fluid Dynamics (CFD) is carried out using pure water with a hot water flow rate ranging between 1-2 l/min for the coil side heat exchanger. For single coil heat exchangers, the numerical analysis findings showed a good agreement with experimental four-temperature measurement results (T-1, T-2, T-3 and T-4) with an error rate of 1.80%, 3.05%, 5.34% and 2.17% respectively. Moreover, in the current double coil analysis, the hot outlet temperature decreased by 3.07% compared to a single coil (baseline case) at a 2.5L/min hot water flow rate. In addition, increasing the coil pitch will increase the contact between the hot fluid and the coil at a constant hot water flow rate and thereby decrease the hot fluid outlet temperature. Finally, a computational analysis was carried out to examine the flow structure inside single and double coil heat exchangers, and the findings indicated that the effect of centrifugal forces in double coil heat exchangers at various coil pitches caused the secondary flow to be substantially reduced.

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Никулин, Н., e Nikolay Nikulin. "THE STUDY OF HEAT TRANSFER IN INTENSIFIED SHELL AND TUBE DEVICE". Bulletin of Belgorod State Technological University named after. V. G. Shukhov 4, n.º 4 (25 de abril de 2019): 77–82. http://dx.doi.org/10.34031/article_5cb1e65e6c0d28.53980880.

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The use and prevalence of heat exchangers in Russian heat supply systems are considered. Attention is paid to the improvement of serial heat exchangers with smooth tubes – the increasing of heat transfer coefficient. One of the ways to increase the heat transfer coefficient is considered: it is the turbuliza-tion of the fluid flow on the heat exchange surface. The original design of the heat exchange surface for shell and tube devices of heat supply systems is presented. The dynamics of the heated fluid in the annular space of a shell and tube heat exchanger when flowing around the heat exchange surface with a modified geometry is studied (RF Patent 149737). A feature of the dynamics is a circular edge (element of the surface of heat exchange), which contributes to the creation of turbulence in the flow of the heated liquid on the plate and on the surface of the next edge. Emphasis is placed on heat ex-change processes between the solid surface of the edges and the heated fluid. For a circular cross sec-tion, the equation of thermal conductivity in cylindrical coordinates is compiled, taking into account the stationary heat exchange process, with an internal source of thermal energy. Solution of equation makes possible to determine the change in temperature on the surface and the average temperature of the edge. This value allows determining the Prandtl number to calculate the heat transfer coefficient.

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Aydin, Ahmet, Halit Yaşar, Tahsin Engin e Ekrem Büyükkaya. "Optimization and CFD analysis of a shell-and-tube heat exchanger with a multi segmental baffle". Thermal Science, n.º 00 (2020): 293. http://dx.doi.org/10.2298/tsci200111293a.

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The Shell-and-tube type heat exchangers have long been widely used in many fields of industry. These types of heat exchangers are generally easy to design, manufacturing and maintenance, but require relatively large spaces to install. Therefore the optimization of such heat exchangers from thermal and economical points of view is of particular interest. In this article, an optimization procedure based on the minimum total cost (initial investment plus operational costs) has been applied. Then the flow analysis of the optimized heat exchanger has been carried out to reveal possible flow field and temperature distribution inside the equipment using computational fluid dynamics. The experimental results were compared with computational fluid dynamics analyses results. It has been concluded that the baffles play an important role in the development of the shell side flow field. This prompted us to investigate new baffle geometries without compromising from the overall thermal performance. It has been found that the heat exchanger with the new baffle design gives rise to considerably lower pressure drops in the shell side, which in turn reducing operating cost. The new baffle design is particularly well suited for shell-and-tube heat exchangers, where a viscous fluid flows through shell side with/out phase change.

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Walter, Christian, Sebastian Martens, Christian Zander, Carsten Mehring e Ulrich Nieken. "Heat Transfer through Wire Cloth Micro Heat Exchanger". Energies 13, n.º 14 (10 de julho de 2020): 3567. http://dx.doi.org/10.3390/en13143567.

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The main objective of this study is to calculate and determine design parameters for a novel wire cloth micro heat exchanger. Wire cloth micro heat exchangers offer a range of promising applications in the chemical industry, plastics technology, the recycling industry and energy technology. We derived correlations to calculate the heat transfer rate, pressure drop and temperature distributions through the woven structure in order to design wire cloth heat exchangers for different applications. Computational Fluid Dynamics (CFD) simulations have been carried out to determine correlations for the dimensionless Euler and Nusselt numbers. Based on these correlations, we have developed a simplified model in which the correlations can be used to calculate temperature distributions and heat exchanger performance. This allows a wire cloth micro heat exchanger to be virtually designed for different applications.

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Kamidollayev, Tlegen, Juan Pablo Trelles, Jay Thakkar e Jan Kosny. "Parametric Study of Panel PCM–Air Heat Exchanger Designs". Energies 15, n.º 15 (30 de julho de 2022): 5552. http://dx.doi.org/10.3390/en15155552.

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Heat exchangers, devices for the transfer of heat between two or more working fluids, are extensively used in cooling applications and heating applications. Heat exchangers in buildings are typically components of space-conditioning systems, as well as of water-heating applications. Heat exchangers are also sometimes used in applications that require storage and release of energy at specific times. Phase change materials (PCMs) enhance these heat-exchange processes, given their ability to melt and solidify at a fixed range of temperatures, absorbing or releasing significant amounts of latent heat. Five different configurations of PCM–air heat exchangers for thermal control in buildings are analyzed in this work. The heat exchangers were fitted with PCM encapsulated in plastic and composite pouches of various shapes, and packaged in stackable panel layers. Three-dimensional computational fluid dynamics (CFD) modeling of coupled incompressible fluid and conjugate heat transfer were performed on the designs. The phase change process was numerically modelled using the apparent heat capacity method. Steady-state CFD simulations provided quantification of pressure drop as a function of air flow velocity. Transient simulation results describe the thermal evolution of PCM in the pouches, helping to determine the best performing configuration with respect to total thermal charging time.

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Trokhaniak, V. I., I. L. Rogovskii, L. L. Titova, P. S. Popyk, O. O. Bannyi e P. H. Luzan. "Computational fluid dynamics investigation of heat-exchangers for various air-cooling systems in poultry houses". Bulletin of the Karaganda University. "Physics" Series 97, n.º 1 (30 de março de 2020): 125–34. http://dx.doi.org/10.31489/2020ph1/125-134.

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The increase in the productivity of poultry plants is connected with the necessity to create the optimal controlled environment in poultry houses. This problem is of prime importance due to the decrease of poultry plant productivity caused by the imperfection of the existing controlled environment systems. The paper presents the improved environment control system in a poultry house. The processes of heat- and mass-exchange in the developed heat-exchangers for various ventilation systems have been investigated. Computational Fluid Dynamics analysis of the heat-exchangers of two various designs for tunnel and side ventilation systems has been carried out. The fields of velocities, temperatures and pressures in the channels under study have been obtained. The conditions of a hydrodynamic flow in the channels have been analyzed. The intensity of heattransfer between a hot heat carrier and a cold one through their separating wall has been estimated. The most efficient heat-exchanging apparatus has been determined and the application potential of such a design has been substantiated. The aim of the research is the development and numerical modelling of a shell-and-tube heat-exchanger of a new design as an element of environment control system used in various types of ventilations systems in summer seasons.

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Fetuga, Ibrahim Ademola, Olabode Thomas Olakoyejo, Adeola S. Shote, Gbeminiyi Mike Sobamowo, Omotayo Oluwatusin e Joshua Kolawole Gbegudu. "Thermal and Fluid Flow Analysis of Shell-and-Tube Heat Exchangers with Smooth and Dimpled Tubes". Journal of Advanced Engineering and Computation 6, n.º 3 (30 de setembro de 2022): 233. http://dx.doi.org/10.55579/jaec.202263.378.

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This current work mainly focuses on the enhancement of the heat transfer and fluid flow characteristics of shell-and-tube heat exchangers by incorporating dimples on the smooth or conventional tubes. With the aid of the ANSYS (Fluent) commercial software package, Computational Fluid Dynamics (CFD) simulations under a steady-state condition were conducted on heat exchanger having a single shell and 12 tubes (with or without dimples), 50% baffle cut, 100mm baffle spacing and turbulent flow. The temperature, velocity, and pressure fields at the shell and tube zone in both cases are analyzed. The computational fluid dynamics results of the heat exchanger with dimpled tubes are compared with conventional (smooth) tubes. However, the results show that a shell and tube heat exchanger with dimpled tubes has a higher overall heat transfer coefficient than that of conventional (smooth) tubes. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

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Hughes, J. P., T. E. R. Jones e P. W. James. "Numerical Simulations and Experimental Measurements of the Isothermal Flow in a Model Tubular Heat Exchanger". Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 220, n.º 2 (1 de maio de 2006): 109–19. http://dx.doi.org/10.1243/095440806x78847.

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This paper describes numerical simulations and experimental measurements of isothermal laminar flow on the shell side of a model tubular heat exchanger, for both Newtonian and non-Newtonian fluids. Commercially available computational fluid dynamics software is used for the simulations, which are shown to be in good agreement with experimental measurements of shear rate and pressure drop. The simulations can then be used to provide a detailed description of the laminar shell-side flow in the model tubular heat exchanger. The motivation for this work stems from interest in the food processing industry in using tubular heat exchangers in heat recovery mode for medium viscosity food products. In this mode, the food product flows on the shell side as well as through the tubes. The shell-side flow is then laminar and aspects of the performance of the heat exchanger may be unsatisfactory. The work described in this paper forms part of a wider study in which validated numerical simulations are used in the design of tubular heat exchangers operating in heat recovery mode for medium viscosity food products.

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Sundén, Bengt. "Computational Fluid Dynamics in Research and Design of Heat Exchangers". Heat Transfer Engineering 28, n.º 11 (novembro de 2007): 898–910. http://dx.doi.org/10.1080/01457630701421679.

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Chennu, Ranganayakulu. "Numerical analysis of compact plate-fin heat exchangers for aerospace applications". International Journal of Numerical Methods for Heat & Fluid Flow 28, n.º 2 (5 de fevereiro de 2018): 395–412. http://dx.doi.org/10.1108/hff-08-2016-0313.

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Purpose The purpose of this study is to find the thermo-hydraulic performances of compact heat exchangers (CHE’s), which are strongly depending upon the prediction of performance of various types of heat transfer surfaces such as offset strip fins, wavy fins, rectangular fins, triangular fins, triangular and rectangular perforated fins in terms of Colburn “j” and Fanning friction “f” factors. Design/methodology/approach Numerical methods play a major role for analysis of compact plate-fin heat exchangers, which are cost-effective and fast. This paper presents the on-going research and work carried out earlier for single-phase steady-state heat transfer and pressure drop analysis on CHE passages and fins. An analysis of a cross-flow plate-fin compact heat exchanger, accounting for the individual effects of two-dimensional longitudinal heat conduction through the exchanger wall, inlet fluid flow maldistribution and inlet temperature non-uniformity are carried out using a Finite Element Method (FEM). Findings The performance deterioration of high-efficiency cross-flow plate-fin compact heat exchangers have been reviewed with the combined effects of wall longitudinal heat conduction and inlet fluid flow/temperature non-uniformity using a dedicated FEM analysis. It is found that the performance deterioration is quite significant in some typical applications due to the effects of wall longitudinal heat conduction and inlet fluid flow non-uniformity on cross-flow plate-fin heat exchangers. A Computational Fluid Dynamics (CFD) program FLUENT has been used to predict the design data in terms of “j” and “f” factors for plate-fin heat exchanger fins. The suitable design data are generated using CFD analysis covering the laminar, transition and turbulent flow regimes for various types of fins. Originality/value The correlations for the friction factor “f” and Colburn factor “j” have been found to be good. The correlations can be used by the heat exchanger designers and can reduce the number of tests and modification of the prototype to a minimum for similar applications and types of fins.

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Naqvi, S. M. A., e Qiuwang Wang. "Numerical Comparison of Thermohydraulic Performance and Fluid-Induced Vibrations for STHXs with Segmental, Helical, and Novel Clamping Antivibration Baffles". Energies 12, n.º 3 (9 de fevereiro de 2019): 540. http://dx.doi.org/10.3390/en12030540.

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The most extensively used heat exchanger in numerous research fields and industrial processes is the shell and tube heat exchanger. The selection of the baffle plays a vital role to regulate and increase the thermohydraulic performance and also to decrease fluid-induced vibrations due to shell side flow. 3-D computational fluid dynamics (CFD) and fluid-structure interaction (FSI) have been done to analyze the pressure drop, heat transfer coefficient, vortex shedding, and tube deformation due to induced vibrations among the recently developed clamping antivibration baffles with square twisted tubes, helical baffles with cylindrical tubes, and conventional segmental baffles with cylindrical tubes at different shell side flow rates by using commercial software ANSYS. Complete heat exchangers are modeled for numerical comparison; the thermohydraulic performance of the numerical model shows the suitable agreement by validating it with already published results and Esso method for single segmental baffles. It is then used to compare the performance of the same heat exchangers with CBSTT and HBCT. Thermohydraulic performance of CBSTT-STHX is better than SGCT-STHX. The heat transfer coefficient of heat exchangers with tube-to-baffle-hole clearance is higher and there is a reduction in the pressure drop compared to the results of STHXs without tube-to-baffle-hole clearance. The deformation in the tubes and vortex-induced vibrations are minimum in STHX with CBSTT than in STHXs with HBCT and SGCT.

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Kaviany, M., e M. Reckker. "Performance of a Heat Exchanger Based on Enhanced Heat Diffusion in Fluids by Oscillation: Experiment". Journal of Heat Transfer 112, n.º 1 (1 de fevereiro de 1990): 56–63. http://dx.doi.org/10.1115/1.2910364.

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The results of a study on the performance of a heat exchanger that takes advantage of enhanced heat diffusion in oscillated fluids are presented. In this heat exchanger, the fluid occupies a bundle of capillary tubes that connects two reservoirs at different temperatures; a piston in each reservoir drives the oscillation. The experimental findings are compared with predictions based on the assumptions that (a) a capillary tube does not exchange heat with the neighboring tubes, (b) the pressure in the reservoirs undergoes an ideal sinusoidal motion, and (c) each reservoir has an infinite heat capacity such that the fluid entering the tubes is at a constant temperature. Good agreement has been found between the actual performance of the heat exchanger and the idealized analysis for low and high frequencies. However, around the frequency corresponding to optimum performance, i.e., where the thermal boundary layers occupy the entire cross section of the capillary tubes, agreement is only fair. The measurements show that there is a temperature variation across the bundle and that the fluid entering the tubes has a nonsteady temperature due to weak, nonuniform mixing within the reservoirs (therefore, a spatial/temporal average was taken). This lateral and temporal variation in the temperature distribution appears to be the leading cause of the difference between the experimental and predicted results. As with any heat pipe, the reduction in the resistance to heat flow in the pipe must be accompanied by a similar ease of heat flow to and away from the ends of the pipe. Therefore, the reservoir fluid dynamics is of paramount importance in these heat exchangers. Some numerical modeling of the fluid flow in the reservoirs, as well as some velocity measurements (using a laser-Doppler anemometer), are also presented.

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Álvarez Gómez, Pascual, Ismael Rodríguez Maestre, F. Javier González Gallero e J. Daniel Mena Baladés. "The Influence of Outer Weather Conditions on the Modelling of Vertical Ground Heat Exchangers". Applied Mechanics and Materials 361-363 (agosto de 2013): 276–80. http://dx.doi.org/10.4028/www.scientific.net/amm.361-363.276.

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Policies for energy saving and carbon dioxide emission reduction have enouraged the use of efficient technologies in building thermal conditioning, like geothermal source heat pumps [. Most of the thermal models used to simulate the performance of vertical ground heat exchangers do not consider the effect of outer weather conditions, except for the setting of the initial ground temperature [. This paper shows a study to assess the effect of outer weather conditions on the outlet fluid temperature, especially during the upper part of the exchanger. Different depths for typical configurations of ground heat exchangers have been analysed. Detailed simulations have been developed for a full year of performance using a commercial finite volume computational fluid dynamics (CFD) code (©ANSYS-CFX). Outer weather conditions have been set by using synthetic hourly weather data and considering all of the heat transfer phenomena involved. Errors in outlet fluid temperature and surface borehole temperature have been estimated for the whole year of simulation.

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Nurhasanah, Siti, Muhammad Subekti, Moch Nurul Subkhi e Bebeh Wahid Nuryadin. "Optimal tube diameter on heat exchanger shell and tube type with 15 mega watt thermal power using fluent 6.3". MATEC Web of Conferences 197 (2018): 02011. http://dx.doi.org/10.1051/matecconf/201819702011.

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Heat exchanger shell and tube type is a set of tools that serve to move the heat from the side shell (hot fluid) to the tube (cold fluid). RSG-GAS Heat Exchangers is a heat exchanger shell and tube type 2-2. Since the age of Heat Exchanger operation long enough allow for new designs of heat transfer better. This is one reason the presence of micro modeling using Computational Fluid Dynamics (CFD), as one of them using the software FLUENT 6.3. Tube and shell modeled in GAMBIT with the variation ID (inner diameter) tube. As for the physical data such as flow rate, pressure, and temperature refers to the RSG-GAS Heat Exchangers. The first variation is the different mesh sizes for the tube that has the same diameter. Mesh size of 0.8 mm had the best result so do the meshing used as a benchmark for other models. Variations of 2D models use inner diameter from 20 mm until 26m. From CFD calculations using FLUENT 6.3 for 2D models, in the can that ID 20 mm, 23 mm and 26 mm can be used as models for 3D calculations. Of 3D calculations it can be concluded that the tube with an ID of 26 mm have the most optimal heat transfer is equal to 273,24669 K with a pressure drop of 450 Pa.

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Ladeinde, Foluso. "Reduced-Order Computational-Fluid-Dynamics-Based Analysis of Aviation Heat Exchangers". Journal of Thermophysics and Heat Transfer 34, n.º 4 (outubro de 2020): 696–715. http://dx.doi.org/10.2514/1.t5903.

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Konchada, Pavan Kumar, Vinay Pv e Varaprasad Bhemuni. "Statistical analysis of entropy generation in longitudinally finned tube heat exchanger with shell side nanofluid by a single phase approach". Archives of Thermodynamics 37, n.º 2 (1 de junho de 2016): 3–22. http://dx.doi.org/10.1515/aoter-2016-0010.

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AbstractThe presence of nanoparticles in heat exchangers ascertained increment in heat transfer. The present work focuses on heat transfer in a longitudinal finned tube heat exchanger. Experimentation is done on longitudinal finned tube heat exchanger with pure water as working fluid and the outcome is compared numerically using computational fluid dynamics (CFD) package based on finite volume method for different flow rates. Further 0.8% volume fraction of aluminum oxide (Al2O3) nanofluid is considered on shell side. The simulated nanofluid analysis has been carried out using single phase approach in CFD by updating the user-defined functions and expressions with thermophysical properties of the selected nanofluid. These results are thereafter compared against the results obtained for pure water as shell side fluid. Entropy generated due to heat transfer and fluid flow is calculated for the nanofluid. Analysis of entropy generation is carried out using the Taguchi technique. Analysis of variance (ANOVA) results show that the inlet temperature on shell side has more pronounced effect on entropy generation.

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Alsahil, Muath I., Mowffaq M. Oreijah e Mohamed H. Mohamed. "Quantitative and Qualitative Study of Double-Pipe Heat Exchangers Performance Using Water Based Nanofluids". Journal of Nanofluids 11, n.º 6 (1 de dezembro de 2022): 924–43. http://dx.doi.org/10.1166/jon.2022.1891.

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The heat transfer performance of base fluids is greatly improved with suspended nanoparticles in a variety of applications such as solar collectors, heat pipes, nuclear reactors, cooling systems, automotive radiators, and more. In the present paper, the problem of flow of nanofluids with forced convection is studied in detail in three cases, under constant mass flow rates (Case 1), under optimized mass flow rates with two different geometric configuration scenarios of the heat exchangers, N-shaped pipe heat exchanger (Case 2) and M-shaped pipe heat exchanger (Case 3). Numerical results in the previous works, as obtained for water–Al2O3 mixture, have been demonstrated that of nanoparticles into the base fluids fluid led to a significant increase of the heat transfer coefficient, which clearly increases with an increase in particle concentration. However, those particals also caused drastic effects on the wall shear stress that increases correspondingly with the particle loading. Therefore, in the current study the full performance of the different heat exchanger designs will be investigated numerically under the effect of different particle concentrations and different nano materials such as Al2O3, CuO, TiO2 and SiO2. Additionally, the Computational Fluid Dynamics (CFD) single-phase model is adopted for predicting the heat transfer performance in fluent using ANSYS. Therefore, the results show enhancement in heat transfer for the heat exchanger is due to increased volume fraction, and a direct correlation between overall heat transfer effectiveness and volume fraction percentage of nanofluids, while CuO was proven most effective amongst considered nano particles. Besides, adjusting the geometry into an M-shaped pipe had resulted in an enhanced heat transfer effectiveness.

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Shafagh, Ida, Simon Rees, Iñigo Urra Mardaras, Marina Curto Janó e Merche Polo Carbayo. "A Model of a Diaphragm Wall Ground Heat Exchanger". Energies 13, n.º 2 (7 de janeiro de 2020): 300. http://dx.doi.org/10.3390/en13020300.

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Ground thermal energy is a sustainable source that can substantially reduce our dependency on conventional fuels for heating and cooling of buildings. To exploit this source, foundation sub-structures with embedded heat exchanger pipes are employed. Diaphragm wall heat exchangers are one such form of ground heat exchangers, where part of the wall is exposed to the basement area of the building on one side, while the other side and the further depth of the wall face the surrounding ground. To assess the thermal performance of diaphragm wall heat exchangers, a model that takes the wall geometry and boundary conditions at the pipe, basement, and ground surfaces into account is required. This paper describes the development of such a model using a weighting factor approach, known as Dynamic Thermal Networks (DTN), that allows representation of the three-dimensional geometry, required boundary conditions, and heterogeneous material properties. The model is validated using data from an extended series of thermal response test measurements at two full-scale diaphragm wall heat exchanger installations in Barcelona, Spain. Validation studies are presented in terms of comparisons between the predicted and measured fluid temperatures and heat transfer rates. The model was found to predict the dynamics of thermal response over a range of operating conditions with good accuracy and using very modest computational resources.

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Khanlari, Ataollah, Adnan Sözen e Halil İbrahim Variyenli. "Simulation and experimental analysis of heat transfer characteristics in the plate type heat exchangers using TiO2/water nanofluid". International Journal of Numerical Methods for Heat & Fluid Flow 29, n.º 4 (1 de abril de 2019): 1343–62. http://dx.doi.org/10.1108/hff-05-2018-0191.

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PurposeThe plate heat exchangers (PHE) with small size but large efficiency are compact types of heat exchangers formed by corrugated thin pressed plates, operating at higher pressures when compared to most other traditional exchangers. This paper aims to analyze heat transfer characteristics in the PHE experimentally and numerically.Design/methodology/approachComputational fluid dynamics analysis has been used to simulate the problem by using the ANSYS fluent 16 software. Also, the effect of using TiO2/water nanofluid as working fluid was investigated. TiO2/water nanofluid had 2% (Wt/Wt) nanoparticle content. To improve solubility of the TiO2nanoparticles, Triton X-100 was added to the mixture. The results have been achieved in different working condition with changes in fluid flow rate and its temperature.FindingsThe obtained results showed that using TiO2/water nanofluid improved the overall heat transfer coefficient averagely as 6%, whereas maximum improvement in overall heat transfer coefficient was 10%. Also, theoretical and experimental results are in line with each other.Originality/valueThe most important feature which separates the present study from the literature is that nanofluid is prepared by using TiO2nanoparticles in optimum size and mixing ratio with surfactant usage to prevent sedimentation and flocculation problems. This process also prevents particle accumulation that may occur inside the PHE. The main aim of the present study is to predict heat transfer characteristics of nanofluids in a plate heat exchanger. Therefore, it will be possible to analyze thermal performance of the nanofluids without any experiment.

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Song, Su Fang. "Performance Study of Heat Exchangers with Continuous Helical Baffles on Different Inclination Angles". Advanced Materials Research 655-657 (janeiro de 2013): 461–64. http://dx.doi.org/10.4028/www.scientific.net/amr.655-657.461.

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The three-dimensional model of heat exchangers with continuous helical baffles was built. The fluid flow dynamics and heat transfer of shell side in the helical baffled heat exchanger were simulated and calculated. The velocity, pressure and temperature distributions were achieved. The simulation shows that with the same baffle pitch, shell-side heat transfer coefficient increased by 25% and the pressure drop decreases by 18% in helical baffled heat exchanger compared with segmental helical baffles. With the analyzing of the flow and heat transfer in heat exchanger in 5 different inclination angles from 11°to 21°, it can be found that both shell side heat transfer coefficient and pressure drop will reduce respectively by 86% and 52% with the increases 11°to 21°of the inclination angles. Numerical simulation provided reliable theoretical reference for further engineering research of heat exchanger with helical baffles.

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Agarwal, Abhishek. "Modelling & Numerical Investigation of the Effectiveness of Plate Heat Exchanger for Cooling Engine Oil Using ANSYS CFX". International Journal of Heat and Technology 39, n.º 2 (30 de abril de 2021): 653–58. http://dx.doi.org/10.18280/ijht.390237.

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Heat exchangers are used for various industrial application for transfer of enthalpy from hot fluid to cold. One of them is Plate Heat Exchanger which finds its application in evaporating systems. The compactness, high effectiveness and easy maintenance of Plate Heat Exchanger makes it best choice for process industries. The current research investigates the application of Plate Heat Exchanger in cooling of engine oil using techniques of Computational Fluid Dynamics for low, medium and high Reynolds number using ANSYS CFX software. The CAD model is developed using Creo design software and turbulence model used for analysis is RNG k-epsilon which gives good predictions for complex flows involving swirls. The CFD analysis is conducted for different values of Reynolds number. The temperature distribution, effectiveness and overall heat transfer coefficient is determined for different values of Reynolds number.

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Rus, Alexandru, Vlad Martian e Mihai Nagi. "Study of Height Influence of Heat Exchanger Tanks on Overall Pressure Drop". Applied Mechanics and Materials 659 (outubro de 2014): 446–49. http://dx.doi.org/10.4028/www.scientific.net/amm.659.446.

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In the context of a constant demand of more compact and efficient heat exchangers, the need for thoroughly researching the influence of the construction parameters impact on heat exchanger's performances arises. The purpose of the paper is to present the numerical results of such a research, carried out at RAAL S.A. with the support of "Politehnica" University of Timişoara. The research consists of assessing the effects of the geometric characteristics, the height in particular, of the inlet and outlet tanks of a water cooler on overall pressure drop, through Computational Fluid Dynamics. The structural complexity of heat exchangers demands that the analysis be divided into multiple, less complex models, in order to achieve accurate and truthful results within a reasonable amount of time and use of computational resources. The paper also focuses on developing a viable method for accomplishing numerical analyses on heat exchangers' parameters.

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Porter, Michael A., Dennis H. Martens, Thomas Duffy e Sean McGuffie. "High-Temperature Heat Exchanger Tube-Sheet Assembly Investigation With Computational Fluid Dynamics". Journal of Pressure Vessel Technology 129, n.º 2 (20 de novembro de 2006): 313–15. http://dx.doi.org/10.1115/1.2716436.

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Many modern sulfur recovery unit process waste heat recovery exchangers operate in high-temperature environments. These exchangers are associated with the thermal reactor system where the tube-sheet–tube-ferrule assemblies are exposed to gasses at temperatures approaching 3000°F. Because sulfur compounds are present in the process gas, the carbon steel tube sheet and tubes in the assembly will be deteriorated by sulfidation as the operating metal temperature rises above 600°F. Ferrule systems are used to protect the carbon steel from exposure to excessive temperatures. The temperature distribution in the steel tube-sheet–tube-ferrule system is affected by process gas flow and heat transfer through the assembly. Rather than depend on “assumed” heat transfer coefficients and fluid flow distribution, a computational fluid dynamics investigation was conducted to study the flow fields and heat transfer in the tube-sheet assembly. It was found that the configuration of the ferrule installation has a large influence on the temperature distribution in the steel materials and, therefore, the possible sulfidation of the carbon steel parts.

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de Souza, Diego Amorim Caetano, Lúben Cabezas Gómez e José Antônio da Silva. "Fluid Dynamic Simulation and Optimization of Compact Heat Exchangers with Louver Fins". Applied Mechanics and Materials 798 (outubro de 2015): 205–9. http://dx.doi.org/10.4028/www.scientific.net/amm.798.205.

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Every technological process developed since the beginning of humanity to the present day always involves some kind of energy use, either mechanical energy of the body or energy from burning fuel or the solar energy obtained from the sun. To manipulate and use that energy, the man always developed resources and equipment to allow it. Among the wide range of equipment, heat exchangers, designed to transfer heat from one fluid to another, will be analyzed in this work. To do this analysis, are used computational fluid dynamics (CFD) techniques to analyze the flow behavior of a compact heat exchanger, of tube and louvered fins type. After this step that aims to pull the parameters of efficiency, optimization features will be used to be able to propose a model for more efficient fin.

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Ajeeb, Wagd, Monica S. A. Oliveira, Nelson Martins e S. M. Sohel Murshed. "Numerical approach for fluids flow and thermal convection in microchannels". Journal of Physics: Conference Series 2116, n.º 1 (1 de novembro de 2021): 012049. http://dx.doi.org/10.1088/1742-6596/2116/1/012049.

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Abstract The heat transfer performance of conventional thermal fluids in microchannels is an attractive method for cooling devices such as microelectronic applications. Computational fluid dynamics (CFD) is a very significant research technique in heat transfer studies and validated numerical models of microscale thermal management systems are of utmost importance. In this paper, some literature studies on available numerical and experimental models for single-phase and Newtonian fluids are reviewed and methods to tackle laminar fluid flow through a microchannel are sought. A few case studies are selected, and a numerical simulation is performed to obtain fluid flow behaviour within a microchannel, to test the level of accuracy and understanding of the problem. The numerical results are compared with relevant experimental results from the literature and a proper methodology for numerical investigation of single-phase and Newtonian fluid in laminar flow convection heat transfer in microscale heat exchangers is defined.

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Liu, Liu, e Yingwen Liu. "Numerical study on a thermoacoustic refrigerator with continuous and staggered arrangements". Thermal Science, n.º 00 (2022): 25. http://dx.doi.org/10.2298/tsci210901025l.

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Thermoacoustic devices require heat exchangers with oscillating flow, but there is currently no viable design approach for them. A heat exchanger with a staggered structure can efficiently improve the velocity disturbance and promote heat transfer in steady flow. The flow and heat transfer characteristics of a standing-wave thermoacoustic refrigerator and an ambient heat exchanger with staggered parallel plates under the oscillating flow condition are investigated in this study, primarily focusing on the geometric influences and differences between staggered and non-staggered (continuous) arrangements. Computational fluid dynamics simulation is a mainstream tool for the numerical simulation of complex thermoacoustic phenomena. The flow field around the stack and heat exchanger plate is simulated by introducing the dynamic mesh boundary conditions. Through numerical simulation, the flow field characteristics of nonlinear vortices generation around the heat exchanger are presented. By changing the staggered column number in the ambient heat exchanger, it is observed that the larger the column number of staggered parallel plates, the more significant the refrigeration effect through the thermoacoustic effect.

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van Driel, Michael R. "Cardioplegia heat exchanger design modelling using computational fluid dynamics". Perfusion 15, n.º 6 (dezembro de 2000): 541–48. http://dx.doi.org/10.1177/026765910001500611.

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A new cardioplegia heat exchanger has been developed by Sorin Biomedica. A three-dimensional computer-aided design (CAD) model was optimized using computational fluid dynamics (CFD) modelling. CFD optimization techniques have commonly been applied to velocity flow field analysis, but CFD analysis was also used in this study to predict the heat exchange performance of the design before prototype fabrication. The iterative results of the optimization and the actual heat exchange performance of the final configuration are presented in this paper. Based on the behaviour of this model, both the water and blood fluid flow paths of the heat exchanger were optimized. The simulation predicted superior heat exchange performance using an optimal amount of energy exchange surface area, reducing the total contact surface area, the device priming volume and the material costs. Experimental results confirm the empirical results predicted by the CFD analysis.

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Khan, Abdullah, Imran Shah, Waheed Gul, Tariq Amin Khan, Yasir Ali e Syed Athar Masood. "Numerical and Experimental Analysis of Shell and Tube Heat Exchanger with Round and Hexagonal Tubes". Energies 16, n.º 2 (12 de janeiro de 2023): 880. http://dx.doi.org/10.3390/en16020880.

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Shell and tube heat exchangers are used to transfer thermal energy from one medium to another for regulating fluid temperatures in the processing and pasteurizing industries. Enhancement of a heat transfer rate is desired to maximize the energy efficiency of the shell and tube heat exchangers. In this research work, we performed computational fluid dynamics (CFD) simulations and experimental analysis on the shell and tube heat exchangers using round and hexagonal tubes for a range of flow velocities using both parallel flow and counter flow arrangements. In the present work, the rate of heat transfer, temperature drop, and heat transfer coefficient are computed using three turbulence models: the Spalart–Allmaras, the k-epsilon (RNG), and the k-omega shear stress transport (SST). We further utilized the logarithmic mean temperature difference (LMTD) method to compute the heat transfer and mass flow rates for both parallel and counter flow arrangements. Our results show that the rate of heat transfer is increased by introducing the hexagonal structure tubes, since it has better flow disruption as compared to the round tubes. We further validated our simulation results with experiments. For more accurate results, CFD is performed in counter and parallel flow and it is deduced that the rate of heat transfer directly depends upon the velocity of fluids and the number of turns of the tube.

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Navickaitė, Kristina, Michael Penzel, Christian R. H. Bahl e Kurt Engelbrecht. "Performance Assessment of Double Corrugated Tubes in a Tube-In-Shell Heat Exchanger". Energies 14, n.º 5 (1 de março de 2021): 1343. http://dx.doi.org/10.3390/en14051343.

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In this article, the performance of double corrugated tubes applied in a tube-in-shell heat exchanger is analysed and compared to the performance of a heat exchanger equipped with straight tubes. The CFD (computational fluid dynamics) analysis was performed considering a turbulent flow regime at several mass flow rates. It is observed that the double corrugated geometry does not have a significant impact on the pressure drop inside the analysed heat exchanger, while it has the potential to increase its thermal performance by up to 25%. The ε–NTU (effectiveness–number of transfer units) relation also demonstrates the advantage of using double corrugated tubes in tube-in-shell heat exchangers over straight tubes.

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JUN, SOOJIN, e VIRENDRA M. PURI. "3D milk-fouling model of plate heat exchangers using computational fluid dynamics". International Journal of Dairy Technology 58, n.º 4 (novembro de 2005): 214–24. http://dx.doi.org/10.1111/j.1471-0307.2005.00213.x.

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Menni, Younes, Houari Ameur, Shao-Wen Yao, Mohammed Amine Amraoui, Mustafa Inc, Giulio Lorenzini e Hijaz Ahmad. "Computational fluid dynamic simulations and heat transfer characteristic comparisons of various arc-baffled channels". Open Physics 19, n.º 1 (1 de janeiro de 2021): 51–60. http://dx.doi.org/10.1515/phys-2021-0005.

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Abstract In this analysis, the baffling method is used to increase the efficiency of channel heat exchangers (CHEs). The present CFD (computational fluid dynamics)-based work aims to analyze the constant property, steady, turbulent, Newtonian, and incompressible fluid flow (air), in the presence of transverse-section, arc-shaped vortex generators (VGs) with two various geometrical models, i.e., arc towards the inlet section (called arc-upstream) and arc towards the outlet section (called arc-downstream), attached to the hot lower wall, in an in-line situation, through a horizontal duct. For the investigated range of Reynolds number (from 12,000 to 32,000), the order of the thermal exchange and pressure loss went from 1.599–3.309 to 3.667–21.103 times, respectively, over the values obtained with the unbaffled exchanger. The arc-downstream configuration proved its superiority in terms of thermal exchange rate by about 14% than the other shape of baffle. Due to ability to produce strong flows, the arc-downstream baffle has given the highest outlet bulk temperature.

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Wu, H. L., Y. Gong e X. Zhu. "Air Flow and Heat Transfer in Louver-Fin Round-Tube Heat Exchangers". Journal of Heat Transfer 129, n.º 2 (21 de maio de 2006): 200–210. http://dx.doi.org/10.1115/1.2402180.

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Experimental investigations were conducted to understand the air flow and heat transfer in louver-fin round-tube two-row two-pass cross-counterflow heat exchangers. The Colburn factor j and friction factor f were obtained by using the ε-NTU approach. A three-dimensional computational fluid dynamics model was developed based on a representative unit cell with periodical and symmetric boundary conditions. Analysis of tube-side circuiting effect has been conducted and showed improvement by applying overall nonlinear tube-side fluid temperature boundary conditions. Comparison of heat transfer rate of the first and second rows showed that the first row was much more effective, achieving 68-53% of the total heat transfer rate, when air velocity changes from 1.02m∕sto2.54m∕s. A dimensionless parameter, F, was introduced to describe the louver interaction for different fin designs with various louver angles. Using j′∕f1∕3 as a criterion to evaluate the heat transfer and pressure loss performance, an optimal F was predicted around 0.62.

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Hu, Ping Fang, Zhong Yi Yu, Fei Lei, Na Zhu, Qi Ming Sun e Xu Dong Yuan. "Performance Evaluation of a Vertical U-Tube Ground Heat Exchanger Using a Numerical Simulation Approach". Advanced Materials Research 724-725 (agosto de 2013): 909–15. http://dx.doi.org/10.4028/www.scientific.net/amr.724-725.909.

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A vertical U-tube ground heat exchanger can be utilized to exchange heat with the soil in ground source heat pump systems. The outlet temperature of the working fluid through the U-tube not only accounts for heat transfer capacity of a ground heat exchanger, but also greatly affects the operational efficiency of heat pump units, which is an important characteristic parameter of heat transfer process. It is quantified by defining a thermal effectiveness coefficient. The performance evaluation is performed with a three dimensional numerical model using a finite volume technique. A dynamic simulation was conducted to analyze the thermal effectiveness as a function of soil thermal properties, backfill material properties, separation distance between the two tube legs, borehole depth and flow velocity of the working fluid. The influence of important characteristic parameters on the heat transfer performance of vertical U-tube ground heat exchangers is investigated, which may provide the references for the design of ground source heat pump systems in practice.

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Dwivedi, Anil Kumar, e Sarit Kumar Das. "Dynamics of plate heat exchangers subject to flow variations". International Journal of Heat and Mass Transfer 50, n.º 13-14 (julho de 2007): 2733–43. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2006.11.029.

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Sharma, Shubham, Shalab Sharma, Mandeep Singh, Parampreet Singh, Rasmeet Singh, Sthitapragyan Maharana, Nima Khalilpoor e Alibek Issakhov. "Computational Fluid Dynamics Analysis of Flow Patterns, Pressure Drop, and Heat Transfer Coefficient in Staggered and Inline Shell-Tube Heat Exchangers". Mathematical Problems in Engineering 2021 (1 de junho de 2021): 1–10. http://dx.doi.org/10.1155/2021/6645128.

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In this numerical study, the heat transfer performance of shell-and-tube heat exchangers (STHXs) has been compared for two different tube arrangements. STHX having 21 and 24 tubes arranged in the inline and staggered grid has been considered for heat transfer analysis. Shell-and-tube heat exchanger with staggered grid arrangement has been observed to provide lesser thermal stratification as compared to the inline arrangement. Further, the study of variation in the mass flow rate of shell-side fluid having constant tube-side flow rate has been conducted for staggered grid structure STHX. The mass flow rate for the shell side has been varied from 0.1 kg/s to 0.5 kg/s, respectively, keeping the tube-side mass flow rate as constant at 0.25 kg/s. The influence of bulk mass-influx transfer rate on heat transfer efficiency, effectiveness, and pressure drop of shell-tube heat exchangers has been analyzed. CFD results were compared with analytical solutions, and it shows a good agreement between them. It has been observed that pressure drop is minimum for the flow rate of 0.1 kg/s, and outlet temperatures at the shell side and tube side have been predicted to be 40.94°C and 63.63°C, respectively.

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Dirkse, Martijn H., Wilko K. P. van Loon, Tom van der Walle, Sebastiaan L. Speetjens e Gerard P. A. Bot. "A Computational Fluid Dynamics Model for Designing Heat Exchangers based on Natural Convection". Biosystems Engineering 94, n.º 3 (julho de 2006): 443–52. http://dx.doi.org/10.1016/j.biosystemseng.2006.04.007.

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Močnik, Urban, Bogdan Blagojevič e Simon Muhič. "Numerical Analysis with Experimental Validation of Single-Phase Fluid Flow in a Dimple Pattern Heat Exchanger Channel". Strojniški vestnik – Journal of Mechanical Engineering 66, n.º 9 (15 de setembro de 2020): 544–53. http://dx.doi.org/10.5545/sv-jme.2020.6776.

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A plate heat exchanger with a dimple pattern heat plate has a large number of dimples. The shape of dimples defines the characteristics of the plate heat exchanger. Although such heat exchangers have become increasingly popular due to their beneficial characteristics, knowledge of the flow characteristics in such kind of channel is poor. A good knowledge of the flow conditions inside of such channel is crucial for the successful and efficient development of new products. In this paper single-phase water flow in dimple pattern plate heat exchanger was investigated with application of computational fluid dynamics and laboratory experiments. Numerical analysis was performed with two turbulence models, Realizable - with enhanced wall treatment function and - SST. The first predicts a slightly smaller pressure drop and the second slightly larger compared to the results of laboratory measurements. Our research found that despite the relatively low velocity of the fluid, turbulent flow occurs in the channel due to its shape. We also found that there are two different flow regimes in the micro plate heat exchanger channel. The first regime is the regime that dominates the heat transfer, and the second is the regime where a recirculation zone appears behind the brazing point, which reduces the surface for heat transfer. The size of the second regime does not change significantly with the velocity of the fluid in the volume considered.

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Sonjaya, Abeth Novria, Marhaenanto Marhaenanto, Mokhamad Eka Faiq e La Ode M. Firman. "Analisis Perbandingan Jenis Material Penukar Kalor Plat Datar Aliran Silang Untuk Proses Pengeringan Kayu". Jurnal Teknologi 9, n.º 1 (30 de novembro de 2021): 60–71. http://dx.doi.org/10.31479/jtek.v9i1.117.

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The processed wood industry urgently needs a dryer to improve the quality of its production. One of the important components in a dryer is a heat exchanger. To support a durable heat transfer process, a superior material is needed. The aim of the study was to analyze the effectiveness of the application of cross-flow flat plate heat exchangers to be used in wood dryers and compare the materials used and simulate heat transfer on cross-flow flat plate heat exchangers using Computational Fluid Dynamic simulations. The results showed that there was a variation in the temperature out of dry air and gas on the flat plate heat exchanger and copper material had a better heat delivery by reaching the temperature out of dry air and gas on the flat plate type heat exchanger of successive cross flow and. overall heat transfer coefficient value and the effectiveness value of the heat exchanger of the heat transfer characteristics that occur with the cross-flow flat plate type heat exchanger in copper material of 251.74725 W/K and 0.25.

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Gizatullin, R. R., S. N. Peshcherenko e N. A. Lykova. "Simulation of oil cooling of a submersible motor using a heat exchanger". Вестник Пермского университета. Физика, n.º 1 (2021): 69–75. http://dx.doi.org/10.17072/1994-3598-2021-1-69-75.

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Submersible motors are part of submersible oil production pumps that convert electrical energy, which is supplied through a cable from VSD, into mechanical energy of pump rotation. Currently, in about 30% of cases, the failure of an electrical submersible pump is due to a failure of the submersible motor. One of the main causes of failures is overheating of the stator winding insulation. Overheating of submersible oil-filled electric motors occurs because more heat is generated inside the motor than is removed through its outer surface. To intensify the heat removal, it is proposed to connect a heat exchanger in series with the motor and to organize the circulation of the oil in a closed loop. Both in the submersible motor and in the heat exchanger, oil flows along the annular gap along the inner surface of the housing, the oil channel is closed through a hole inside the shaft. The aim of the work is to select such a configuration of the annular channel, in which its length would be minimal. Intensification of heat removal by increasing the speed of the coolant is not advisable, because requires the motor to be equipped with a powerful pump for pumping oil, which will become an additional source of heat. Therefore, it was decided to increase the surface area of the annular channel through which heat, through the body of the installation, is removed to the well fluid. A series of calculations was performed for heat exchangers with smooth walls, with fins (perpendicular to the flow direction), and with spiral grooves (which additionally increase the length of the trajectory of oil particles and the time of their thermal contact with the stacks of the heat exchanger body). Computational fluid dynamics calculations showed that heat exchangers made according to the first two design options removed less than half of the heat. According to the third option, the oil was cooled practically to the temperature of the well fluid with a heat exchanger length of about 10% of the submersible motor length.

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Mikielewicz, Jarosław, e Dariusz Mikielewicz. "Thermal-hydraulic issues of flow boiling and condensation in organic Rankine cycle heat exchangers". Archives of Thermodynamics 33, n.º 1 (1 de agosto de 2012): 41–66. http://dx.doi.org/10.2478/v10173-012-0002-3.

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Thermal-hydraulic issues of flow boiling and condensation in organic Rankine cycle heat exchangers In the paper presented are the issues related to the design and operation of micro heat exchangers, where phase changes can occur, applicable to the domestic micro combined heat and power (CHP) unit. Analysed is the stability of the two-phase flow in such unit. A simple hydraulic model presented in the paper enables for the stability analysis of the system and analysis of disturbance propagation caused by a jump change of the flow rate. Equations of the system dynamics as well as properties of the working fluid are strongly non-linear. A proposed model can be applicable in designing the system of flow control in micro heat exchangers operating in the considered CHP unit.

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Yu, Qin, Chai, Huang e Liu. "The Effect of Compressible Flow on Heat Transfer Performance of Heat Exchanger by Computational Fluid Dynamics (CFD) Simulation". Entropy 21, n.º 9 (25 de agosto de 2019): 829. http://dx.doi.org/10.3390/e21090829.

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As a part of vehicle thermal management, water-cooled intercoolers play an important role in engine efficiency. The incompressible simulation model was usually applied to estimate the performance of water-cooled intercoolers. In this paper, the computational fluid dynamics (CFD) compressible model is taken to analyze more accurate prediction models. The rate of section change, heat exchange, and the surface friction coefficient are used as the comparison basis of the compressible flow model and incompressible model on the pressurized air side of the water-cooled intercooler. By comparing the simulation results of the air side, it was found that the compressible simulation is closer to the experimental value than the incompressible simulation. Compared with the experiment, the compressible model heat transfer maximum value of deviation is 6.5%, and the pressure loss maximum deviation is 7.5%. This provides guidance to optimize the design of heat exchangers, in order to save on costs and shorten development times.

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Salmi, Mohamed, Benameur Afif, Ali Akgul, Rabab Jarrar, Hussein Shanak, Younes Menni, Hijaz Ahmad e Jihad Asad. "Turbulent flows around rectangular and triangular turbulators in baffled channels a computational analysis". Thermal Science 26, Spec. issue 1 (2022): 191–99. http://dx.doi.org/10.2298/tsci22s1191s.

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The present paper highlights a computational analysis of air-flows around rectangular and triangular turbulators inside baffled heat exchanger channels in order to improve heat transfer between the fluid and their heated areas. The dynamic and thermal fields as well as fluid temperature curves at the outlet of the exchanger are studied. The computational study is conducted by utilizing SIMPLE algorithm with FLUENT system based on the finite volumes. The analysis clearly demonstrated the presence of highly turbulent flows and the appearance of many vortices in various regions of the exchanger. By comparing the different heat exchangers, it was found that the baffled channel fitted with rectangular turbulators produced high fluid temperature values at the channel outlet, indicating the significance of using this rectangular form of turbulators in order to enhance the interaction between the hot spaces and the used fluid.

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Berce, Jure, Matevž Zupančič, Matic Može e Iztok Golobič. "A Review of Crystallization Fouling in Heat Exchangers". Processes 9, n.º 8 (1 de agosto de 2021): 1356. http://dx.doi.org/10.3390/pr9081356.

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A vast majority of heat exchangers suffer from unwanted deposition of material on the surface, which severely inhibits their performance and thus marks one of the biggest challenges in heat transfer. Despite numerous scientific investigations, prediction and prevention of fouling remain unresolved issues in process engineering and are responsible for large economic losses and environmental damage. This review article focuses specifically on crystallization fouling, providing a comprehensive overview of the state-of-the-art of fouling in heat exchangers. The fundamentals of the topic are discussed, as the term fouling resistance is introduced along with distinct fouling behaviour, observed in laboratory and industrial environments. Insight into subsequent phases of the fouling process is provided, along with the accompanying microscale events. Furthermore, the effects of fluid composition, temperature, flow velocity, surface condition, nucleate boiling and composite fouling are comprehensively discussed. Fouling modelling is systematically reviewed, from the early work of Kern and Seaton to recently used artificial neural networks and computational fluid dynamics. Finally, the most common fouling mitigation approaches are presented, including design considerations and various on-line strategies, as well as off-line cleaning. According to our review, several topics require further study, such as the initial stage of crystal formation, the effects of ageing, the interplay of two or more fouling mechanisms and the underlying phenomena of several mitigation strategies.

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Huang, Bo Wun, Jung Ge Tseng e Jao Hwa Kuang. "Vibration of a Tube with the Axial Loads and Fluid". Applied Mechanics and Materials 275-277 (janeiro de 2013): 925–29. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.925.

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Vibration of a tube with the fluid and axial load is focused. In a heat exchanger, the tubes are frequently affected by external force and fluid shock waves. Thus, tubes are often found to be vibrated. This vibration may alter the performance of the tubes and global heat exchanger. That a heat exchanger system is weakly coupled as the each tube is coupled to the adjacent one through the fluid is found. To understand the global system dynamics, the dynamics of a tube must be investigated first. In this work, the dynamic properties of a tube with the axial loads are investigated. The Galerkin method employed, the equation of a tube with the fluid effect can be to derive. Numerical results reveal that the axial load and fluid effects may affect the dynamic properties of a tube with fluid significantly.

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Yasuo, A., e M. P. Paidoussis. "Flow-Induced Instability of Heat-Exchanger Tubes due to Axial Flow in a Diffuser-Shaped, Loose Intermediate Support". Journal of Pressure Vessel Technology 111, n.º 4 (1 de novembro de 1989): 428–34. http://dx.doi.org/10.1115/1.3265700.

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In some heat exchangers and steam generators, the flow is predominantly axial, and the external fluid flows between baffled compartments through enlarged holes in the baffles around the heat exchanger tubes. Thus, the tube is subjected to relatively high flow velocities over small portions of its length, in the baffle locations. In this paper, the dynamics of such an idealized system is investigated, involving a cylindrical beam with pinned ends in axial flow, going through a baffle plate of finite thickness at some intermediate point, with small radial clearance. The fluid forces along the tube are formulated in a manner reminiscent of the transfer-matrix technique, since the character of these forces changes drastically along the tube. The fluid forces are determined approximately by means of potential flow theory, and viscous effects are taken into account only in a global sense. It was found that if the flow passage through the baffle plate is diffuser-shaped, negative fluid-dynamic damping is generated therein, destabilizing the system and leading to flutter at relatively low flow velocities. The instability depends critically on the shape of the hole through the baffle and on the clearance; thus a convergent-type flow passage does not lead to instability. The negative fluid-dynamic damping is linearly proportional to the flow velocity through the baffle.

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Chen, Tang, e Wei-zong Wang. "Modeling of combustion and hydrodynamics for a coal-fired supercritical boiler with double-reheat cycle". International Journal of Numerical Methods for Heat & Fluid Flow 30, n.º 4 (23 de fevereiro de 2019): 1661–75. http://dx.doi.org/10.1108/hff-08-2018-0456.

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Purpose The design and retrofit of the heat exchangers in a boiler should take into account the processes occurring on the side of combustion and steam. For this reason, this study aims to couple a one-dimensional hydrodynamic model of steam with computational fluid dynamics (CFD) simulation of flue gas. Design/methodology/approach Radiant/semi-radiant platen heat exchangers are simplified as plane surfaces for CFD, while convective heat exchangers are introduced into the CFD simulation as energy/momentum absorption sources. Findings Numerical simulation is performed for a 1,000 MWe coal-fired ultra-supercritical boiler. The calculation results are validated by the thermodynamic design data. Tube outside surface temperature, as well as ash deposit temperature distributions, are obtained. Originality/value Complex tube arrangements can be completed with the aid of AutoCAD, and therefore, the simulation could offer detailed information of heat exchangers. In a word, a more reliable modeling of the whole steam generation process is achieved.

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Ünverdi, Murat, e Hasan Küçük. "Performance comparison of plate heat exchangers designed using Taguchi method and Computational Fluid Dynamics". Pamukkale University Journal of Engineering Sciences 25, n.º 4 (2019): 373–86. http://dx.doi.org/10.5505/pajes.2019.35493.

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Ünverdi, Murat, e Hasan Küçük. "Performance comparison of plate heat exchangers designed using Taguchi method and Computational Fluid Dynamics". Pamukkale University Journal of Engineering Sciences 25, n.º 4 (2019): 373–86. http://dx.doi.org/10.5505/pajes.2018.35493.

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Sakib, Shadman, e Abdullah Al-Faruk. "Flow and Thermal Characteristics Analysis of Plate–Finned Tube and Annular–Finned Tube Heat Exchangers fo In–Line and Staggered Configurations". Mechanics and Mechanical Engineering 22, n.º 4 (2 de setembro de 2020): 1407–18. http://dx.doi.org/10.2478/mme-2018-0110.

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AbstractAs the effective selection of fin can greatly enhance the performance of heat exchanger, heat transfer and pressure drop performance on the air-side of annular and rectangular finned tube heat exchangers were numerically investigated. Two types of tube arrangement (in-line and staggered alignment) were examined for 6 different air flow rate for both the heat exchangers using computational fluid dynamics software package ANSYS FLUENT. Renormalization group theory (RNG) based k-ε turbulence model was employed to handle the unsteady three-dimensional flow and the conjugate heat transfer characteristics. The exit temperature were determined from the simulated results and then the LMTD, heat transfer rate and air-side heat transfer coefficient were calculated. The numerical flow visualization results revealed few important aspects, such as, the development boundary layers between the fins, the formation of the horseshoe vortex system, and the local variations of the velocity and temperature on the fin geometries. The result shows that as the air flow rate increased the exit temperature decreased but the overall heat transfer increased. Staggered configuration shows higher heat transfer characteristics over the in-line configuration. The rectangular finned tube shows 17 to 24% improvement in heat transfer over the annular finned tube.

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Muthusamy, P., e Palanisamy Senthil Kumar. "Waste Heat Recovery Using Matrix Heat Exchanger from the Exhaust of an Automobile Engine for Heating Car’s Passenger Cabin". Advanced Materials Research 984-985 (julho de 2014): 1132–37. http://dx.doi.org/10.4028/www.scientific.net/amr.984-985.1132.

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The main objective of our work is to analysis the heat transfer rate for various fluids with different matrix heat exchanger (MHE) models and flow characteristic in matrix heat exchanger by using computational fluid dynamics (CFD) package with small car. The amount of heat carried by the cold fluid from hot fluid is mainly depends upon the mass flow rate of the working fluid. The heat transfer area per unit volume of tube is more. So, it increases the temperature of the cold fluid. Here, the hot and cold fluids are moving in the alternate tubes of heat exchanger in the counter flow direction. The small amounts of pressure drop are occurred but which is less compared to existing model. Flow disturbances are rectified in the MHE through the modifications made. Since, silicon carbide material is used as a polishing material to avoid the deposit of carbon at the inner side of the flow passage and this waste heat energy is used for heating passenger cabin during winter season. The wood is used as an insulating material to avoid the heat flow from fluid to atmosphere. Keywords-Heat transfer rate, Matrix heat exchanger, Working fluid, Polishing material.

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