| Summary: | 博士 === 大同工學院 === 機械工程研究所 === 81 === Based on the unit cell model, experimental and numerical
studies on the effective thermal conductivity of porous
material with spherical inclusions in a tetragonal or simple
cubic array have been performed. As the unit cell is in simple
cubic array, the results are in good agreement with some
existing models predicted by Maxwell [23], Rayleigh [24], and
Davis [28]. As to the unit cell in tetragonal array, all the
experimental and numerical results show that the distance
between the spheres in the direction of heat flow has a more
significant effect on the effective thermal conductivity than
other directions. In addition, the transverse effective thermal
conductivity of composite containing long rectangularly shaped
conductors in a matrix with rectangular or staggered pattern
has been investigated by finite element method. Finally, the
fully developed laminar mixed convection in a vertical channel
embedded in porous media has been solved by non-Darcian flow
model. For the boundary conditions on the left and right walls
prescribed as isothermal-isothermal, the exact solution for
temperature and velocity profiles are obtained to investigate
the influence of Darcian force, buoyancy force and boundary
effect. The numerical solution is also provided to investigate
their further influence due to the existence of inertia force.
The exact solution and Nusselt number for isoflux-isoflux
boundary conditions are also derived by using non-Darcy flow
model. Meanwhile, the parametric zone for the occurrence of
flow reversal based on the analytical solutions are presented.
|
|---|
