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The thesis concentrates
upon the possibilities to minimize the
electric energy absorbed during the wood
drying process. The proposed solutions
refer mainly to the minimization of the
rotation speed of the fans and the aerodynamic
resistance determined by the timber stacks.
The approach had as starting
point the present aerodynamics of drying
kilns, which is deficitary, as it ensures
only poor participation of the air volume
and non-uniform air flow within the kiln
and the stacks.
This disadvantages imply
the maintaining of the policy to oversize
the air flow that is necessary for the
drying process, and implicitely to induce
an oversized energy consumption. Based
on the application AeroKilnSoft V.2.0
of original conception, it has been established
that an air addition of 10% leads to the
increase of the absorbed energy by 33%.
The attempt for the decrease
of the aerodynamic resistance of the material
stacks was performed by analyzing the
following variants: the use of stickers
with various thicknesses, the alternative
setting of the timber rows in vertical
plane and supplementary, the use of aerodynamic
profiles. The numerical results shown
that by attaching aerodynamic profiles
at the beginning and at the end of each
timber row, the aerodynamic resistance
of the stack decreases without affecting
the air velocity through the active channels
between the timber boards. However, the
experimental values shown that the advantages
generated by the proposed solution are
not sufficient enough to compensate, from
economically point of view, the disadvantage
of the drying capacity decrease.
In order to minimize
the air losses through passive channels,
using numerical analysis and own experimental
measurements during drying tests with
spruce timber, the optimum variant of
placing the baffles was determined. The
selected solution lead to an increase
of the air velocity inside the stacks.
This advantage allowed
the development of a program for adjusting
the rotation speed of the fans according
to the optimal air flow velocity, with
positive effects on the electric energy
consumption and the drying cost per cubic
meter of wooden material.
The reduced cost of implementing
the proposed solution to industrial scale
kilns creates the premises for the practical
application of this research results.
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