Note: Descriptions are shown in the official language in which they were submitted.
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MODULAR DEVICE FOR CONVERTING WAVE ENERGY
The invention relates to hydropower engineering, namely to devices for
converting
and using wave energy.
There is a known modular device for using wave energy, comprising a wave-
receiving chamber, which is formed by a bottom and guide walls tapering to the
impeller
location, comprising a central cone-shaped dome and annular-shaped blades that
have a
section in the form of a symmetrical segment. The wave-receiving chamber is
further
divided by guide partitions that bend around the impeller and is provided with
a hatch and
a discharge tray (see Patent of Ukraine No. 36832 AFO3B13 / 12).
The disadvantage of this device is the need to orient the inlet directly
against the
wave, and this is associated with energy costs comparable or exceeding the
expected
power of the device. In addition, the vertical location of the impeller
rotation axis does not
allow the use of gravitational forces that arise during reciprocating motion
of water masses
in the surface layers of a water body.
There is a known device for converting wave energy on the water surface into
mechanical energy that has a horizontal axis of rotation and contains a
plurality of
containers that are interconnected and uniformly arranged cyclically in
series,
symmetrically about the axis of rotation and at a certain distance from the
axis of rotation
and form a solid structure comprising at least one full turn of the
containers; wherein each
container is limited with a housing that has a front section relative to the
direction of
device rotation, a rear section relative to the direction of device rotation
and the middle
section located between the front section and the rear section. Herewith the
rear section of
each housing has an inlet opening through which the internal cavity of the
container
communicates with the environment, and the front section of the container
housing is
provided with a valve, which enables passage of fluid only in the inward
direction to the
container and prevents flow of the fluid in the outward direction from the
container (see
Patent of Ukraine UA No. 62659, F03B13/12).
The disadvantages of the device include the use of valves and their bad
location. The
authors suggest that a certain part of the useful work will be carried out at
the expense of
the weight of the water held in the container behind the closed valve located
in the front
section of the container. In static, this will certainly give a torque to the
entire device. But,
in dynamics, this leads to the fact that when the whole structure rotates,
there is a counter-
impact or "slap" of the rising wave upon the container front sections closed
with the
valves, which must be lowered. And, since the valves have a significant
hydraulic
resistance, then there are significant reversible loads that counteract the
force of gravity to
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these containers and Archimedes' force to opposite containers and stop the
rotation of the
entire device. And this in turn leads to the fact that the device does not
have time to work
efficiently with further lowering of the wave due to the need to overcome the
inertia force
in order to perform the desired rotational motion.
The closest by the technical essence and reachable effect to the claimed
converter is
a modular device for converting wave energy [utility model patent UA No.
75844,
F03B13/12. Modular device for converting wave energy / Litovchenko Mikhail
Yuryevich, Litovchenko Mikhail Mikhailovich applied on July 2, 2012, published
on
December 10, 2012] (prototype), which includes a rotatable wave-receiving
chamber made
of several working chambers in the form of toroidal segments, open on one side
and closed
on the other side with the valve.
The disadvantages of the prototype include the use of valves to regulate the
liquid
flow, which are depicted in the corresponding drawing in the form of a plate
or a thick
plate. While testing the model of a small size, the valve performed its
functions
confidently enough and at the right time. But, when trying to increase the
power of the
device by increasing its geometric dimensions and the cross-section of the
working
chambers, certain problems arose during the subsequent field experiments. The
valve
constantly "delayed" and the water did not have time to empty duly the
corresponding
working chamber. Various elastic materials for the valve have been tested, but
all in vain.
The reason was that behind the valve the water remained stationary relative to
the
chambers and the valve with the whole plane "leaned" against it. And this
prevented it
from opening fully in time. And in the semi-open position, it overlapped most
of the open
flow area, thereby creating additional hydraulic resistance. As a result, the
process of
filling and emptying the working chambers with water was prolonged when the
wave was
raised or lowered, which led to extremely undesirable reverse loads. And since
the valve
was in this position for sufficiently long time, it constantly slowed down and
sometimes
even stopped the rotation of the device, which greatly reduced its real
efficiency.
The invention is based on the task of improving the device for converting wave
energy, in particular, the design of working chambers, which will allow using
kinetic
energy of the reciprocal motion of surface waves without losses, regardless of
their size,
direction and configuration.
The problem is solved by the fact that in the known modular wave energy
converter,
comprising a rotating wave-receiving chamber made of several working chambers
in the
form of toroidal segments open on one side and closed on the other side with
the valve,
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according to the invention, the working chambers on one and/or on the other
side are
covered with ventilation grilles.
The claimed invention is represented in Fig. 1 by a general view of the module
comprising one rotating wave-receiving chamber, which consists of three
working
chambers, and a fragment of the central body (hereinafter referred to as the
module) in
configuration with closed ventilation grilles on the rear sides of the working
chambers.
Ventilation grilles in the drawing version are depicted with rigid, flat
moving shutters. To
explain the operating principle, Fig. 2 and Fig.3 show the dynamic schemes.
The working
chamber 1 depicted in Fig. 1 is fixed to the fragment of the central body 5
and has a front
side 2 and a rear side 3 relative to the direction of rotation. In the
drawing, the rear side 3
of the working chamber 1 is closed by a ventilation grill 4. But in some
cases, depending
on the conditions of use, the working chamber is closed by ventilation grilles
on the front
side or on both sides simultaneously. The choice is made individually in each
case and is
affected primarily by the capacity to prevent clogging and fouling of surfaces
by floating
algae or molluscs, as well as by the geometric dimensions of the device that
depend on the
average wave height in the water area of operation. For the convenience of
service and
transportation in disassembled form, each working chamber can be independently
made of
two or more parts folding compactly into each other. The modules assembled at
the site of
operation are attached coaxially to each other or to a shaft, an axle or any
supporting
structure. To transfer the resulting rotary motion to a generator, pump or
other device for
performing useful work, a drive shaft of arbitrary design is used, which is
not shown in the
figures.
The claimed device operates as follows. The modular wave energy converter is
fixed
by any known method at the installation site so as to be on the surface of the
water in semi-
submerged state. If necessary, the use of hollow floats is possible to ensure
buoyancy. The
incoming waves will arbitrarily temporarily flood and drain individual working
chambers,
creating at the same time an imbalance of forces that ensures the rotation of
the entire
device and the transfer of torque to the device to perform useful work, which
is not shown
in the figure. The circular movement of the working chambers can be
conditionally
divided into the areas of descent (immersion) and ascent (emersion). The
device operation
principle is shown in Fig. 2 and Fig. 3 on the example of the cross section of
one module
of three working chambers:
Phase 1, depicted in Fig. 2: Wave elevation and the relative "immersion" of
the
module.
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On the working chamber 6, which conditionally "ascents" on the ventilation
grille 7,
the shutters are closed under the effect of excessive pressure, which prevents
the flow of
water from outside into the chamber, and the Archimedes' buoyant force FA acts
on it,
creating a torque. In the working chamber 8, which "descends", the shutters on
the
ventilation grille 9 can be freely opened and it is easily filled with water
according to the
principle of communicating vessels.
Phase 2, depicted in Fig. 3: Wave lowering and the relative "emersion" of the
module.
The water that filled the working chamber 8 during the "immersion" of the
module tries to leave the chamber and this creates a certain vacuum in it,
leading to the
closing of the shutters on the ventilation grille 9. As a result, water can no
longer leave the
chamber and its weight FT creates a torque in the same direction as the
Archimedes'
buoyant force FA during the "immersion" in the first phase. In the working
chamber 6,
which "ascents", if necessary, the shutters are opened on the ventilation
grille 7 and it is
freely released from the water, not opposing the rotation of the module.
To confirm the correctness of the assumptions, we built a prototype of one
wave
energy converter module and conducted the tests first in the laboratory and
then in real
conditions on the Sea of Azov. The overall diameter of the module was 1200 mm,
the
cross-section of the working chambers was 300x300mm. The module consisted of
three
working chambers, closed from the rear side with respect to the direction of
rotation by
ventilation grilles with movable shutters. Of course, the shutters did not
provide such
tightness, as the valves. However, as a result, they had much less hydraulic
resistance,
while insignificant losses from fluid leakage were more than offset by the
positive torque
created by the other working chambers.
In the laboratory, one separate working chamber was gradually lowered and
raised in
a rectangular container with water with amplitude of 250 mm and a period of 4
seconds. In
full-scale tests, the height of a real wave ranged within 300 mm with a period
of about 3-4
seconds. The tests were successful and fully confirmed the possibility of
stable operation
of the device. Both during the ascent and descent of the wave, the prototype
of the device
received the desired impulse from the action of Archimedes' force or gravity,
and it was
continuously turned. The main thing is that in the dynamic scheme there were
no
reversible loads, which, in turn, led to the stable operation of the entire
device and a
significant increase in its efficiency.
The carried out tests and preliminary calculations show that the proposed
modular wave
energy converter can be effectively used as an energy source in coastal and
island areas.
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