Axial Heat Conduction Effects in Unsteady Forced Convection Along a Cylinder

1987 ◽  
Vol 109 (3) ◽  
pp. 787-791
Author(s):  
C. D. Surma Devi ◽  
M. Nagaraj ◽  
G. Nath
Keyword(s):  
Heat Conduction ◽  
Forced Convection ◽  
Axial Heat ◽  
Axial Heat Conduction

Fully Developed Laminar Forced Convection in a Circular Duct for Herschel–Bulkley Fluids With Viscous Dissipation and Axial Heat Conduction

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Rabha Khatyr ◽  
Jaafar Khalid-Naciri ◽  
Ali Il Idrissi
Keyword(s):  
Boundary Condition ◽  
Heat Conduction ◽  
Forced Convection ◽  
Viscous Dissipation ◽  
Circular Duct ◽  
Nusselt Numbers ◽  
Asymptotic Values ◽  
Axial Heat ◽  
Laminar Forced Convection ◽  
Axial Heat Conduction

The asymptotic behavior of laminar forced convection in a circular duct for a Herschel–Bulkley fluid of constant properties is analyzed. The viscous dissipation and the axial heat conduction effects in the fluid are both considered. The asymptotic bulk and mixing temperature field, and the asymptotic values of the bulk and mixing Nusselt numbers are determined for every boundary condition, enabling a fully developed region. In particular, it is proved that whenever the wall heat flux tends to zero, the asymptotic Nusselt number is zero. The obtained results are compared to other existing solutions in the literature for Newtonian and non-Newtonian cases.

Axial Heat Conduction in Parallel Flow Microchannel Heat Exchangers

2009 ◽  
Author(s):  
B. Mathew ◽  
H. Hegab
Keyword(s):  
Heat Conduction ◽  
Heat Exchanger ◽  
Parallel Flow ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Microchannel Heat Exchanger ◽  
Cold Fluid ◽  
Axial Heat ◽  
End Wall ◽  
Axial Heat Conduction

This paper deals with the effect of axial heat conduction on the hot and cold fluid effectiveness of a balanced parallel flow microchannel heat exchanger. The ends of wall separating the fluids are subjected to Dirichlet boundary condition. This leads to heat transfer between the microscale heat exchanger and its surroundings and thereby leading to axial heat conduction through the wall separating the fluids. Three one dimensional energy equations were formulated, one for each of the fluids and one for the wall. These equations were solved using finite difference method. The effectiveness of the fluids depends on the NTU, axial heat conduction parameter, and the temperature of the ends of the wall separating the fluids. With decrease in temperature of the end wall at the inlet section of the fluids, while keeping the temperature of the other end wall constant, the effectiveness of the hot and cold fluid increased and decreased, respectively. When the temperature at the ends of the wall separating the heat exchanger is average of the inlet temperature of the fluids then there is no axial heat conduction through the heat exchanger. The effectiveness of a counter flow microchannel heat exchanger is better than that of a parallel flow microchannel heat exchanger subjected to similar operating conditions, i.e. axial heat conduction parameter and end wall temperatures.

Sign in / Sign up

Export Citation Format

Share Document