EFFECTS OF THERMAL DISPERSION AND TURBULENCE IN FORCED CONVECTION IN A COMPOSITE PARALLEL-PLATE CHANNEL: INVESTIGATION OF CONSTANT WALL HEAT FLUX AND CONSTANT WALL TEMPERATURE CASES

2002 ◽  
Vol 42 (4) ◽  
pp. 365-383 ◽  
Author(s):  
A. V. Kuznetsov ◽  
L. Cheng ◽  
M. Xiong
Keyword(s):  
Heat Flux ◽  
Forced Convection ◽  
Wall Temperature ◽  
Parallel Plate ◽  
Wall Heat Flux ◽  
Thermal Dispersion ◽  
Constant Wall Temperature ◽  
Constant Wall Heat Flux ◽  
Plate Channel

Laminar Forced Convection in Transversely Corrugated Microtubes

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
F. Talay Akyildiz ◽  
Dennis A. Siginer
Keyword(s):  
Heat Flux ◽  
Analytical Solution ◽  
Forced Convection ◽  
Wall Temperature ◽  
Wall Heat Flux ◽  
Bulk Temperature ◽  
Straight Tube ◽  
Computational Domain ◽  
Constant Wall Temperature ◽  
Constant Wall Heat Flux

Forced convection heat transfer in fully developed laminar flow in transversely corrugated tubes is investigated for nonuniform but constant wall heat flux as well as for constant wall temperature. Epitrochoid conformal mapping is used to map the flow domain onto the unit circle in the computational domain. The governing equations are solved in the computational domain analytically. An exact analytical solution for the temperature field is derived together with closed form expressions for bulk temperature and Nusselt number for the case of the constant heat flux at the wall. A variable coefficient Helmholtz eigenvalue problem governs the case of the constant wall temperature. A novel semi-analytical solution based on the spectral Galerkin method is introduced to solve the Helmholtz equation. The solution in both constant wall heat flux and constant wall temperature case is shown to collapse onto the well-known results for the circular straight tube for zero waviness.

Heat Transfer to Laminar Flow in Tapered Passages

1965 ◽  
Vol 32 (3) ◽  
pp. 684-689 ◽  
Author(s):  
E. M. Sparrow ◽  
J. B. Starr
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Wall Temperature ◽  
Parallel Plate ◽  
Laminar Flows ◽  
Wall Heat Flux ◽  
Heat Transfer Analysis ◽  
Plate Channel

Consideration is given to the fully developed heat-transfer characteristics of laminar flows in converging and diverging plane-walled passages. The analysis is carried out for the two fundamental thermal boundary conditions of prescribed wall heat flux and prescribed wall temperature. As a prelude to the heat-transfer analysis, a new solution for the velocity distribution is derived on the basis of a linearized momentum equation. The Nusselt number for flow in tapered passages is found to depend on the Reynolds number; this is in contrast to the situation for passages of longitudinally unchanging cross section wherein the Nusselt number is independent of the Reynolds number. In general, the Nusselt number for flow in a plane-walled diverging passage falls below that for the parallel-plate channel, while the Nusselt number for a converging flow is usually higher than that for a parallel-plate channel. Moreover, the fully developed Nusselt numbers for prescribed wall heat flux exceed those for prescribed wall temperature.

Heat-Transfer Effects on the Developing Laminar Flow Inside Vertical Tubes

1966 ◽  
Vol 88 (2) ◽  
pp. 214-222 ◽  
Author(s):  
W. T. Lawrence ◽  
J. C. Chato
Keyword(s):  
Heat Flux ◽  
Transition Process ◽  
Constant Heat Flux ◽  
Wall Heat Flux ◽  
Axial Position ◽  
Fluid Viscosity ◽  
Constant Heat ◽  
Constant Wall Temperature ◽  
Constant Wall Heat Flux ◽  
Vertical Tubes

A numerical method was developed for the calculation of entrance flows in vertical tubes for the cases of upflow or downflow and constant wall heat flux or constant wall temperature. The solutions were in excellent agreement with experimental data obtained with water flowing upward in a vertical heated tube. The results show that both the density and the viscosity have to be treated as nonlinear functions of temperature. Consequently, for the constant heat flux condition, the velocity and temperature profiles constantly change and never reach “fully developed” states. The transition to turbulent flow was also studied. The experimental measurements demonstrated that the transition process depends on the developing velocity profiles. For the constant heat flux case, transition will always occur at some axial position. For a given entrance condition, the distance to transition is fixed by the fluid flow rate and the wall heat flux. For the experimental results, a tentative transition criterion was obtained, which depends only on the velocity profile shape, fluid viscosity, and the entrance Reynolds number.

The Solution of Temperature Development in the Entrance Region of an MHD Channel by the B. G. Galerkin Method

1969 ◽  
Vol 91 (2) ◽  
pp. 212-220 ◽  
Author(s):  
R. C. LeCroy ◽  
A. H. Eraslan
Keyword(s):  
Eigenvalue Problem ◽  
Galerkin Method ◽  
Wall Temperature ◽  
Mathematical Problem ◽  
Considerable Effect ◽  
Constant Wall Temperature ◽  
Axial Conduction ◽  
Temperature Development ◽  
Constant Wall Heat Flux ◽  
Plate Channel

The general mathematical problem of MHD thermal entrance regions is formulated for a parallel plate channel by including Joule heating, viscous dissipation, and the effect of axial conduction. The associated eigenvalue problem is solved by the B. G. Galerkin method and the results are presented for constant wall temperature and constant wall heat flux conditions. It is shown that the particular method has distinct computational advantages over the classical form of solutions. The constant wall temperature case is investigated by employing the solutions of the eigenvalue problem and it is concluded that the axial conduction has considerable effect on the temperature development for low values of Peclet number.

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