On Unsteady Heat Transfer of Combined Free and Forced Convection in Circular Tubes

1963 ◽  
Vol 30 (2) ◽  
pp. 257-262 ◽  
Author(s):  
L. N. Tao
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Wall Temperature ◽  
Time Variation ◽  
Circular Tube ◽  
Unsteady Heat Transfer ◽  
Transient Problem ◽  
Axial Temperature ◽  
Free And Forced Convection ◽  
Transfer Problems

The unsteady heat-transfer problems of combined free and forced convection of a fully developed laminar flow of a heat-generating fluid in a circular tube with constant axial temperature gradient at the wall are investigated. The general solution with arbitrary time-dependent pressure gradient, heat generation, and wall temperature is established by the application of the “generalized Duhamel’s theorem.” Two specific cases are then studied. The results indicate that this type of transient problem has a time-variation of an oscillatory type with decaying amplitude. This time-variation is different from that of forced convection or of combined free and forced convection with constant axial wall temperature.

An Analysis of Laminar Free and Forced Convection between Finite Vertical Parallel Plates

1973 ◽  
Vol 95 (1) ◽  
pp. 53-59 ◽  
Author(s):  
J. Quintiere ◽  
W. K. Mueller
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Wall Temperature ◽  
Parallel Plates ◽  
Constant Property ◽  
Uniform Wall Temperature ◽  
Approximate Analytical Solutions ◽  
Wide Range ◽  
Free And Forced Convection ◽  
Prandtl Numbers

Approximate analytical solutions are presented for constant-property laminar free- and forced-convection flows between finite vertical parallel plates. For free convection, the thermal boundary conditions considered include the thermally symmetric channel with uniform wall temperature or step change in wall temperature and the unsymmetric channel with uniform but unequal wall temperatures. For forced convection and combined free and forced convection, the thermally symmetric and uniform thermal boundary condition is considered. Where possible, results are compared with available numerical and experimental results. Particular attention is given to heat-transfer results, which cover a wide range of Rayleigh and Prandtl numbers. For combined convection the heat-transfer results are related to the impressed pressure difference and flow rate.

On Combined Free and Forced Convection in Channels

1960 ◽  
Vol 82 (3) ◽  
pp. 233-238 ◽  
Author(s):  
L. N. Tao
Keyword(s):  
Forced Convection ◽  
Rectangular Channel ◽  
Complex Function ◽  
Vertical Channel ◽  
Temperature Fields ◽  
Parallel Plates ◽  
Free And Forced Convection ◽  
Energy Equations ◽  
Helmholtz Wave Equation ◽  
Transfer Problems

The heat-transfer problems of combined free and forced convection by a fully developed laminar flow in a vertical channel of constant axial wall temperature gradient with or without heat generations are approached by a new method. By introducing a complex function which is directly related to the velocity and temperature fields, the coupled momentum and energy equations are readily combinable to a Helmholtz wave equation in the complex domain. This greatly reduces the complexities of the problems. For illustrations, the cases of flows between parallel plates and in a rectangular channel are treated. It shows that this method is more direct and powerful than those of previous investigations.

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