Second law analysis of viscous flow through rough tubes subjected to constant heat flux

2006 ◽  
Vol 3 (3) ◽  
pp. 323 ◽  
Author(s):  
S.A. Abdel Moneim ◽  
R.K. Ali
Keyword(s):  
Heat Flux ◽  
Viscous Flow ◽  
Constant Heat Flux ◽  
Second Law ◽  
Constant Heat ◽  
Second Law Analysis ◽  
Flow Through

Second law analysis of compressible flow through a diffuser subjected to constant heat flux at wall

2010 ◽  
Vol 51 (12) ◽  
pp. 2808-2815 ◽  
Author(s):  
Mohammad H. Arshad ◽  
Ramazan Kahraman ◽  
Ahmet Z. Sahin ◽  
Rached Ben-Mansour
Keyword(s):  
Heat Flux ◽  
Compressible Flow ◽  
Constant Heat Flux ◽  
Second Law ◽  
Constant Heat ◽  
Second Law Analysis ◽  
Flow Through

Second Law Analysis of Heat Transfer in Taylor Couette Flow for Pseudoplastic Fluid

2013 ◽  
Author(s):  
A. Hazbavi ◽  
N. Ashrafi ◽  
M. Najafi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Energy Balance ◽  
Couette Flow ◽  
Constant Heat Flux ◽  
Second Law ◽  
Constant Heat ◽  
Second Law Analysis ◽  
Taylor Couette ◽  
Taylor Couette Flow

The Taylor Couette flow of pseudoplastic fluids is examined while dissipation due to viscous effects through the energy balance. The viscosity of fluid is simultaneously dependent on shear rate and temperature. Exponential dependence of viscosity on temperature is modeled through Nahme law and the shear dependency is modeled according to the Carreau equation. Hydrodynamically, stick boundary conditions are applied and thermally, both constant temperature and constant heat flux on the exterior of cylinders are considered. The governing motion and energy balance equations are coupled adding complexity to the already highly correlated set of differential equations. Introduction of Nahme number has resulted in a nonlinear base flow between the cylinders. As well, the condition of constant heat flux has moved the point of maximum temperature towards the inner cylinder. Taking viscous heating into account, the effects of parameters such as Nahme Number, Deborah Number, material time and pseudoplasticity constant on the heat transfer of the flow are investigated by second law analysis. Moreover, the study shows that the total entropy generation number decreases as the fluid elasticity increases. It, however, increases with increasing Nahme Number.

Thermal and Fluid Dynamic Model for Capillary-Driven Heat Pipe With Closed-Form Solution

2017 ◽  
Author(s):  
Jesse Maxwell
Keyword(s):  
Boundary Condition ◽  
Heat Flux ◽  
Closed Form ◽  
Heat Pipe ◽  
Closed Form Solution ◽  
Constant Heat Flux ◽  
Form Solution ◽  
Constant Heat ◽  
Micro Channels ◽  
Flow Through

A model is derived for the steady state performance of capillary-driven heat pipes on the basis treating fluid flow through miniature- and micro-channels and applied as bulk properties to a large aspect ratio quasi-one-dimensional two-phase system. Surface tension provides the driving force based on an equivalent bulk capillary radius while laminar flow through micro-channels and the vapor core are treated. Heat conduction is accounted for radially while isothermal advection is treated along the axis. A closed-form solution is derived for a steady state heat pipe with a constant heat flux boundary condition on the evaporator as well as a constant heat flux or a convective boundary condition along the condenser. Two solution methods are proposed, and the result is compared to empirical data for a copper-water heat pipe. The components of the closed-form solution are discussed as contributors to driving or frictional forces, and the existence of an optimal pore radius is demonstrated.

Stability of Viscous Flow Driven by an Azimuthal Pressure Gradient Between Two Porous Concentric Cylinders With Radial Flow and a Constant Heat Flux at the Inner Cylinder

2012 ◽  
Author(s):  
R. K. Deka ◽  
A. Paul
Keyword(s):  
Heat Flux ◽  
Pressure Gradient ◽  
Viscous Flow ◽  
Radial Flow ◽  
Constant Heat Flux ◽  
Circular Cylinders ◽  
Constant Heat ◽  
Linearized Stability ◽  
Permeable Walls ◽  
Flux Parameter

A linear analysis for the instability of viscous flow between two porous concentric circular cylinders driven by a constant azimuthal pressure gradient is studied, when a radial flow through the permeable walls of the cylinders is present. Also, a constant heat flux at the inner cylinder is applied. The linearized stability equations form an eigenvalue problem, which are solved by using Runge-Kutta-Fehlberg scheme combined with a shooting method, termed unit disturbance method. It is found that the constant heat flux parameter N, even for a radially weak outward flow has a strong stabilizing effect and the stabilization is more as the gap between the cylinders increases.

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