| Summary: | 博士 === 國立臺灣大學 === 化學工程學系 === 86 === The aim of this research is to study the characteristics of
heat transfer and stability of different system. The second law
of thermodynamics is utilized to obtain the minimum entropy
generation, that is, the maximum effective work of the system.
For heat transfer system of fin, it exists very complex states
if the boiling happens on the surface of fins. If the base
temperature is at the film boiling, at least three states
happens: only film boiling occurs on the all fin, film boiling
occurs accompanying with transition boiling, and film＋
transition＋nuclear boiling coexist. If the boiling happens on
the fins, the heat fluxes could be higher than the one without
fins for one order, and the range of operational base
temperature also increases
Plate boiling system has similar characteristics to the wire
boiling. An "equilibrium heat flux" exists to divide the
boiling curve into stable and meta-stable region. Below the
equilibrium heat flux the nucleate boiling will be more stable,
and above the flux film boiling will be the stable state. The
porous layer on the plate will not only increase the heat
transfer efficiency but also the stability. The change in
locations of heating surface will influence the equilibrium
heat flux. If the heati
In the second law analysis, both the irreversibility of heat
transfer and hydrodynamics are considered to obtain the best
Reynolds number to minimum entropy generation. One or two
branch numbers of fractal-like fin has excellent heat transfer
efficiency. The second law suggests that one or two branch
numbers of fractal-like fin, and its subfins should be close to
their mother fin base, and the size should as small as
possible. For pin fin arrays, when on some array regions, the
in-line arrangement w
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