Transient Laminar Mixed Convective Heat Transfer in a Vertical Flat Duct

Lin, T.F.; Yin, C. P.; Yan, Wei‐Mon

doi:10.1115/1.2910573

Cited by 15 publications

(2 citation statements)

References 17 publications

(24 reference statements)

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“…They showed that the axial diffusion of heat in the wall of a tube becomes negligible for the low values of the thermal report/ratio of conductivity solid-fluid or thicknesses of the wall. Lin et al [4] obtained a numerical solution for a unsteady laminar aiding and opposing mixed convection heat transfer in vertical flat duct. They indicated that unsteady heat transfer characteristics in the flow are principally determined by wall-to fluid heat capacity ratios.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation o f Mixed Convection in a Inclined Thick Duct

Bakhti¹,

Si‐Ameur²

2011

JESTR

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In this work, a numerical study of a laminar mixed convection in a inclined thick duct is considered. A uniform heat flux is applied over the entire circumference of the tube. The governing differential equations were solved by a finite volume method. The SIMPLE algorithm for pressure-velocity coupling was adopted. A parametric study is carried out to analyze the effect of the Grashof number, the angle of the duct inclination and the wall conductivity on the thermal-fluid fields. Several numbers of Grashof (4. 104, 4. 106, 4. 107) are considered for an angle of inclination equal: 0°, 30° and 60°. For material of the wall, we chose Report/ratio of conductivity (K=kp/kf) of the copper (K=19000), iron (K=3600) and aluminium (K=11500). The results are analyzed by examining the velocity, pressure and temperature fields §. The axial evolution of the Nusselt number and that of the parietal constraints are examined for various studied cases.

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Section: Introductionmentioning

confidence: 99%

Numerical Simulation o f Mixed Convection in a Inclined Thick Duct

Bakhti¹,

Si‐Ameur²

2011

JESTR

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“…Approximation methods in which the thermal capacity of the pipe wall is assumed negligible were proposed by Siege1 (19601, Sucec (1975), and Li (1986). Based on the lumped capacitance approach to the transient heat conduction in the wall, Sucec (1981) and Lin (1991) obtained exact analytical and numerical solutions for a finite wall thermal capacity. Later, Lin and Kuo (1988) included the effect of the internal thermal resistance of the wall by using a one-dimensional (1-D) model of transient heat conduction in the radial direction.…”

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confidence: 99%

Numerical solution for slowdown of pipeline containing flashing liquid

Fairuzov

1998

AIChE Journal

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An intentional or accidental opening in a pipeline containing a subcooled liquid at a high pressure may produce its rapid depressurization (blowdown). The liquid starts to flash when its pressure reaches the local saturation pressure and flows thereafter as a two-phase mixture. The modeling of this process plays a crucial role in the analysis of accident scenarios and in the design of controlled depressurization systems in chemical, nuclear, and offshore industries.Prediction of transfer of heat from the pipe wall to the two-phase flow during the depressurization process is a transient conjugated heat-transfer problem since the heat-transfer rate at the wall-fluid interface and local fluid conditions are directly dependent on each other and need to be simultaneously calculated. A number of approaches to the solution of this problem have been developed for a single-phase pipe flow. Approximation methods in which the thermal capacity of the pipe wall is assumed negligible were proposed by Siege1 (19601, Sucec (1975), andLi (1986). Based on the lumped capacitance approach to the transient heat conduction in the wall, Sucec (1981) and Lin (1991) obtained exact analytical and numerical solutions for a finite wall thermal capacity. Later, Lin and Kuo (1988) included the effect of the internal thermal resistance of the wall by using a one-dimensional (1-D) model of transient heat conduction in the radial direction.Much of the past work on the pipeline blowdown has concentrated on the development of models describing the hydrodynamics of the two-phase pipe flow. In these models the flow is assumed either adiabatic or isothermal (Grolmes et al., 1984;Richardson and Saville, 1991). Chen et al. (1995) formulated a model for a two-phase blowdown which takes into account forced convection heat transfer between the pipe wall and the fluid flow. However, the effects of wall thermal capacity and transient conduction are assumed negligible in their study. This approach can be used for heat transfer in flows bounded by very thin walls. The ratio of wall thickness to the internal diameter for steel pipes employed in the transport of flashing liquids reaches 0.13 (Engineering Data Book, 1972) and, therefore, a large amount of heat may be transferred to the fluid during a pipeline blowdown. Solving the conjugate heat-transfer problem for a flashing flow in a pipe is a complex problem due to difficulties associated with the modeling of forced convection in the conditions of twophase flow. The traditional approach to the solution of this problem is based on the use of empirical two-phase forced convection correlations in conjunction with a 1-D or 2-D numerical model of heat conduction in the transverse direction (Erickson and Mai, 1992). Recently, Fairuzov (1998) developed a novel approach to the description of heat transfer in long two-phase pipelines in which the effect of the thermal capacitance of the pipe wall (p,c,,,V,) is incorporated into the energy equation for the fluid flow in the form of an additional term.In this note,...

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Transient Conjugate Heat Transfer During Flashing of Liquids in Pipes

Fairuzov¹

1999

Chem. Eng. Technol.

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In this article, transient conjugate heat transfer during the flashing of liquids in pipes is examined. A numerical model is formulated to simulate a blowdown of a pipeline produced by a partial rupture of a pipe. The model is based on the approach to the description of conjugate two‐phase heat transfer proposed in an earlier study by the author. The effect of the area of the rupture on the wall‐to‐fluid heat transfer is studied. The range of applicability of the novel formulation of energy equation is determined. The use of a new fundamental dimensionless number governing the effect of conjugate heat transfer on flow behavior is shown. This parameter can be very useful for solving the problem of transient flashing liquid flow in pipes.

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Transient Laminar Mixed Convective Heat Transfer in a Vertical Flat Duct

Cited by 15 publications

References 17 publications

Numerical Simulation o f Mixed Convection in a Inclined Thick Duct

Numerical Simulation o f Mixed Convection in a Inclined Thick Duct

Numerical solution for slowdown of pipeline containing flashing liquid

Transient Conjugate Heat Transfer During Flashing of Liquids in Pipes

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