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Numerical Simulation Of Fully Developed Laminar Flow And Heat Transfer In Isothermal Helically Twisted Tubes With Elliptical Cross Sections
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Book Synopsis Numerical Simulation of Fully Developed Laminar Flow and Heat Transfer in Isothermal Helically Twisted Tubes with Elliptical Cross-sections by : Fady Bishara
Download or read book Numerical Simulation of Fully Developed Laminar Flow and Heat Transfer in Isothermal Helically Twisted Tubes with Elliptical Cross-sections written by Fady Bishara and published by . This book was released on 2010 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: Periodically fully-developed swirling laminar flows in twisted tubes with elliptical cross sections are numerically simulated. The tubes are helically twisted along the axis perpendicular to their cross-section. The helical twist geometry is described by the 180 degree twist ratio and the elliptical cross-section is described by the ellipse aspect ratio. The geometries considered for this study have twist ratios with values {3,4.5,6} and ellipse aspect ratios with values {0.3, 0.5, 0.7}. Constant-property flow with a nominal Prandtl number of 3 (e.g. water at 60 degree Celsius) and Reynolds numbers in the range 10 The analysis quantifies the improvement in the Nusselt number as well as the increase in friction factor in order to map the effective heat transfer enhancement due to the twisted-tube-geometry-induced swirl flows. To this effect, the numerical results are compared, for a given aspect ratio, with the case of a straight elliptical tube (i.e. twist ratio tends to infinity) for which well established correlations are available. The results were also compared with those of circular tubes with twisted tape inserts for any given twist ratio. Numerical results show that the friction factor and the Nusselt number are strong functions of the twist ratio, aspect ratio and the Reynolds number. The increase in the friction factor and Nusselt number is higher for more tightly twisted tubes and for tubes with a lower ellipse aspect ratio. For Reynolds numbers below 100, the heat transfer results do not deviate significantly from the straight-tube values, but at higher values of Re, significant enhancement in heat transfer is evident for all twist ratios considered here. For example, for tubes with aspect ratio alpha = 0.3 and a twist ratio y = 3, the enhancement of the Nusselt number relative to the straight tube Nusselt number Nu/Nu(y=infinity) = 2.7. For the same aspect ratio, but with a twist ratio $y=6$, the enhancement Nu/Nu(y=infinity) = 2. On the other hand, for nearly round cross sections (e.g. alpha = 0.7) and nearly straight tubes (e.g. y=6) the enhancement Nu/Nu(y=infinity) ~ 1; i.e. there is no enhancement. The friction factor and Nusselt number results provided in this paper will give practicing engineers the necessary data to integrate twisted elliptical tubes in various heat transfer applications.
Book Synopsis Introduction to Enhanced Heat Transfer by : Sujoy Kumar Saha
Download or read book Introduction to Enhanced Heat Transfer written by Sujoy Kumar Saha and published by Springer. This book was released on 2019-06-29 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Brief stands as a primer for heat transfer fundamentals in heat transfer enhancement devices, the definition of heat transfer area, passive and active enhancement techniques and their potential and benefits and commercial applications. It further examines techniques and modes of heat transfer like single-phase flow and two-phase flow, natural and forced convection, radiation heat transfer and convective mass transfer.
Download or read book Applied mechanics reviews written by and published by . This book was released on 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Computational Modeling of Laminar Swirl Flows and Heat Transfer in Circular Tubes with Twisted-tape Inserts by :
Download or read book Computational Modeling of Laminar Swirl Flows and Heat Transfer in Circular Tubes with Twisted-tape Inserts written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A numerical study is carried out to predict the velocity and temperature distributions in fully developed, constant property, laminar flows in tubes containing twisted-tape inserts. The tape inserts are characterized by the twist ratio y (ratio of 180ʻ twist pitch of the tape H to the tube inner diameter d), and the ratio of tape thickness d to the tube diameter, d / d . The swirl flow is simulated by following the helically twisted flow path in the partitioned tube represented by a semi-circular cross-section geometry. In this model, the tape thickness is neglected (d = 0), which is a reasonable first-order approximation as d / d? [10 -2] for most inserts used in practice. For the numerical solution of the velocity problem, the stream function and vorticity formulation is employed. The corresponding non-linear governing differential equations for the stream function, vorticity, axial velocity and temperature distributions are discretized using the finite control-volume method. This procedure essentially retains the conservative forms of the governing equations, and provides second-order discretization accuracy for the numerical solution. For the heat transfer problem both the uniform wall temperature (UWT) and uniform heat flux (UHF) boundary conditions at the tube wall are considered. In addition, two variations of the tape surface condition are considered, namely, uniform temperature and zero heat flux. These two cases model the tape as having infinite and zero fin efficiency, respectively. Results for the variations in the velocity and temperature fields with flow Reynolds number Re and tape twist ratio y are presented; the temperature distributions also reflects the influence of fluid Prandtl number Pr. The twisted-tape induced swirl flow field is characterized by a single longitudinal vortex that breaks up into two counter-rotating helical vortices with increasing Re or decreasing y . Correspondingly, both the friction factor f and Nusselt number Nu increase substantially; in the case of heat transfer, Nusselt number also increases with Pr. The results for f and Nu are found to agree very well with the respective Manglik and Bergles (1993) correlations. This verifies the scaling of swirl flow effects by the parameter Sw as proposed by them.
Book Synopsis Numerical Investigation of Laminar Flow and Heat Transfer in Circular Duct with Twisted Tape Inserted for Non-Newtonian Fluid by : An Fu
Download or read book Numerical Investigation of Laminar Flow and Heat Transfer in Circular Duct with Twisted Tape Inserted for Non-Newtonian Fluid written by An Fu and published by . This book was released on 2016 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational modeling of fully developed laminar convection of shear thinning fluids in a straight circular pipe with a twisted tape insert is presented in this thesis. The non-Newtonian behavior is modeled by purely viscous power-law and modified power-law relationships. The twisted tape geometry is defined by twist ratio y and the non-Newtonian fluid is characterized by the power-law index n . Because of symmetry between both sides of the tape insert, only one half of the domain consisting of helically twisted semi-circular cross-sectional geometry is modeled. The governing equations of mass and momentum conservation are transformed in terms of stream function and vorticity. The vorticity transport and stream function equations are solved simultaneously with the axial velocity equation and the energy conservation equation using a finite volume method. Both uniform wall temperature (UWT) and uniform heat flux (UHF) boundary conditions are considered. The governing equation are solved with varying Reynolds number (100
Book Synopsis Computation of Flow and Heat Transfer in Helical Pipes by : Alakananda Bandyopadhyay
Download or read book Computation of Flow and Heat Transfer in Helical Pipes written by Alakananda Bandyopadhyay and published by . This book was released on 1993 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Analysis of Turbulent Heat Transfer, Mass Transfer, and Friction in Smooth Tubes at High Prandtl and Schmidt Numbers by : Robert G. Deissler
Download or read book Analysis of Turbulent Heat Transfer, Mass Transfer, and Friction in Smooth Tubes at High Prandtl and Schmidt Numbers written by Robert G. Deissler and published by . This book was released on 1954 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: The expression for eddy diffusivity from a previous analysis was modified in order to account for the effect of kinematic viscosity in reducing the turbulence in the region close to a wall. By using the modified expression, good agreement was obtained between predicted and experimental results for heat and mass transfer at Prandtl and Schmidt numbers between 0.5 and 3000. The effects of length-to-diameter ratio and of variable viscosity were investigated for a wide range of Prandtl numbers.
Book Synopsis Numerical Simulation of Laminar Flow and Heat Transfer in Two- Dimensional Channels by : Paul D. Hancock
Download or read book Numerical Simulation of Laminar Flow and Heat Transfer in Two- Dimensional Channels written by Paul D. Hancock and published by . This book was released on 1992 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Studies of Fully Developed Laminar Flow and Convective Heat Transfer Between Parallel Plates and Through a Tube by : Barbara R. Baron
Download or read book Studies of Fully Developed Laminar Flow and Convective Heat Transfer Between Parallel Plates and Through a Tube written by Barbara R. Baron and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Computational Analyses for Fluid Flow and Heat Transfer in Different Curved Geometries by : Carlin Miller Lucente
Download or read book Computational Analyses for Fluid Flow and Heat Transfer in Different Curved Geometries written by Carlin Miller Lucente and published by . This book was released on 2012 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three-dimensional Computational Fluid Dynamics (CFD) models were developed to simulate fluid flow and heat transfer in a variety of helical channel geometries: circular and elliptical. Laminar flow was observed for Reynolds number between 200 and 1000. Code validation was done for developing steady laminar flow in a circular curved channel. The CFD results were compared to previous numerical results to verify that the model was producing valid results. The curve of the channel has a centrifugal effect on the fluid flow creating secondary flow known as Dean cells. This secondary flow moves the location of the maximum axial velocity towards the outer wall of the channel and alters the developing temperature profiles as well. The helical models were designed to assess if the effect of the curve increases the rate of heat transfer when a constant surface temperature is applied to the wall of the channel. Different channel geometries were used to determine the effects on fluid flow and heat transfer in a helical channel. A channel with a 180° turn was also modeled in two different ways. One with a rounded 180° curve and the other with three perpendicular channels joined together to create a square 180° turn. The three combined channels are typically easier and less expensive to manufacture, but the fluid flow and heat transfer properties need to be considered before selecting the design. The helical models produce similar results. The Dean vortices produced in the secondary flow within the fluid aids in the heat transfer properties of the fluid. Of all the helical cases, a horizontal ellipse cross section achieved the highest outlet-inlet temperature difference, especially for higher Reynolds numbers. Even though the horizontal elliptical helix model produced the highest temperature difference, the circular helix model produced the highest percent increase over its straight model. Using a figure of merit to compare the Nusselt numbers and friction factors for each case, the circular helix geometry proved to me the best design option. The three combined channels produced better heat transfer results than the rounded channel for higher Reynolds numbers, with higher mean outlet temperatures. At lower Reynolds numbers, the results were very similar with only a 0.4% difference in results.
Book Synopsis Modeling of Thermofluid Phenomena in Segmented Network Simulations of Loop Heat Pipes by : Nirmalakanth Jesuthasan
Download or read book Modeling of Thermofluid Phenomena in Segmented Network Simulations of Loop Heat Pipes written by Nirmalakanth Jesuthasan and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The overarching goal of the work presented in this thesis is to formulate, implement, test, and demonstrate cost-effective mathematical models and numerical solution methods for computer simulations of fluid flow and heat transfer in loop heat pipes (LHPs) operating under steady-state conditions.A segmented network thermofluid model for simulating steady-state operation of conventional LHPs with cylindrical and flat evaporators is proposed. In this model, the vapor-transport line, condenser pipe, and liquid-transport line are divided into longitudinal segments (or control volumes). Quasi-one-dimensional formulations, incorporating semi-empirical correlations for the related single- and two-phase phenomena, are used to iteratively impose balances of mass, momentum, and energy on each of the aforementioned segments, and collectively on the whole LHP. Variations of the thermophysical properties of the working fluid with temperature are taken into account, along with...
Book Synopsis Numerical Simulation of Flow Pattern and Heat Transfer Mechanism from a Heated Cylinder in Cross Flow by : Abang Ma'aruf Abang Bussri
Download or read book Numerical Simulation of Flow Pattern and Heat Transfer Mechanism from a Heated Cylinder in Cross Flow written by Abang Ma'aruf Abang Bussri and published by . This book was released on 2009 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theory of lattice Boltzmann method is introduced to simulate a fluid flow numerically. The lattice Boltzmann method has found to be useful in many application involving interfacial dynamics and complex boundaries. First, the introduction of this report is described the objective of the project. This project objective is to study flow pattern and heat transfer mechanism from a heated cylinder in cross flow. The problem statement is explained in further detailed. The problem is solving using the lattice Boltzmann method theory and some flow simulation. This background of the project is related to the lattice Boltzmann method equation that is involving the Navier-Stoke equation, the governing equation and Bhatnagar-Gross-Krook (BGK) approximation. The literature review explains and described further detail about the lattice Boltzmann method. The methodology discusses about the simulation of the isothermal and thermal of the lattice Boltzmann and how to implement mathematical equation into FORTRAN programming language. The isothermal flow includes the Poiseuille and flow past a cylinder in cross flow. The thermal flow includes the flow past a heated cylinder in cross flow. The isothermal and thermal of lattice Boltzmann equation have been derived from the Boltzmann equation by discretization in both time and phase space. The result obtained by numerical simulation, compared to analytical solution.
Book Synopsis Nachträge zu Band 3 und Band 4 (Acanthaceae bis Lythraceae). by :
Download or read book Nachträge zu Band 3 und Band 4 (Acanthaceae bis Lythraceae). written by and published by . This book was released on 1989 with total page 718 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Simulation of Fully-developed Creeping Flow Heat Transfer in Tubes with Twisted Tape Inserts by : C. E. McCumber
Download or read book Simulation of Fully-developed Creeping Flow Heat Transfer in Tubes with Twisted Tape Inserts written by C. E. McCumber and published by . This book was released on 1983 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Heat Transfer with Laminar Flow in Concentric Annuli with Constant and Variable Wall Temperature with [i.e. And] Heat Flux by : Raymond Eugene Lundberg
Download or read book Heat Transfer with Laminar Flow in Concentric Annuli with Constant and Variable Wall Temperature with [i.e. And] Heat Flux written by Raymond Eugene Lundberg and published by . This book was released on 1961 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The general problem of heat transfer in a concentric annulus with hydrodynamically fully established laminar flow is considered. Under the assumptions that the fluid in the annulus is incompressible, has constant properties, and that internal viscous generation is negligible, the differential equation for the temperature field is solved for certain special or fundamental boundary conditions. These fundamental solutions can be superposed to satisfy any general axially symmetric boundary conditions."--P. i.
Book Synopsis An Analysis of Heat Transfer in an Eccentric Annulus for Fully Developed Laminar Flow with Velocity Slip and Temperature Jump Boundary Conditions by : Burton H. Holaday
Download or read book An Analysis of Heat Transfer in an Eccentric Annulus for Fully Developed Laminar Flow with Velocity Slip and Temperature Jump Boundary Conditions written by Burton H. Holaday and published by . This book was released on 1968 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Study of Laminar Flow Forced Convection Heat Transfer Behavior of a Phase Change Material Fluid by : Gurunarayana Ravi
Download or read book Study of Laminar Flow Forced Convection Heat Transfer Behavior of a Phase Change Material Fluid written by Gurunarayana Ravi and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The heat transfer behavior of phase change material fluid under laminar flow conditions in circular tubes and internally longitudinal finned tubes are presented in this study. Two types of boundary conditions, including uniform axial heat flux with constant peripheral temperature and uniform axial and peripheral temperature, were considered in the case of circular tubes. An effective specific heat technique was used to model the phase change process assuming a hydrodynamically fully-developed flow at the entrance of the tube. Results were also obtained for the phase change process under hydro dynamically and thermally fully developed conditions. In case of a smooth circular tube with phase change material (PCM) fluid, results of Nusselt number were obtained by varying the bulk Stefan number. The Nusselt number results were found to be strongly dependent on the Stefan number. In the case of a finned tube two types of boundary conditions were studied. The first boundary condition had a uniform axial heat flux along the axis of the tube with a variable temperature on the peripheral surface of the tube. The second boundary condition had a constant temperature on the outer surface of the tube. The effective specific heat technique was again implemented to analyze the phase change process under both the boundary conditions. The Nusselt number was determined for a tube with two fins with different fin height ratios and fin thermal conductivity values. It was determined that the Nusselt number was strongly dependent on the Stefan number, fin thermal conductivity value, and height of the fins. It was also observed that for a constant heat axial flux boundary condition with peripherally varying temperature, the phase change slurry with the internally finned tube performed better than the one without fins. A similar trend was observed during the phase change process with internal fins under the constant wall temperature boundary condition.
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