Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to a solar water heater.
According to the invention, there is provided a
solar water heater which includes a base member, an upper
member adapted to absorb radiant heat and removably attached
to the base member to define a chamber for liquid therebetween,
an inlet and an outlet for filling and drawing liquid into and
from the chamber, and an intermediate member of an insulative
material dividing the chamber into upper and lower compartments,
the intermediate member having passages therein providing
communication between the upper and lower compartments, the
upper member, the intermediate member and base member being of
saucer shape with concave portions, the concave portions of
the upper member and intermediate member being directed towards
the concave portion of the base member, the upper, intermediate
and base members having outwardly extending peripheral flanges,
and the flange of the intermediate member being clamped between
the flanges of the base member and upper member.
The intermediate member is conveniently located
closer to the upper member than to the base member so that the
upper compartment is smaller than the lower compartment. The
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intermediate member is intended to minimise outward radiation
of heat via the upper member from the major portion of liquid
in the chamber during periods when radiant heat is not being
applied to the upper member.
When the solar water heater is inclined at an angle
to the horizontal to present as much as possible of the surface
of the upper member to direct rays from the sun, at least one
of the passages in the intermediate member is conveniently
controlled by a non-return valve, thereby to permit flow of
lo liquid from the upper compartment to the lower compart~ent via
the non-return valve in the passage or passages located at a
high level. If desired, a further non-return valve may be
provided in the passages located at a low level in the
intermediate member to prevent flow of liquid from the upper
compartment to the lower compartment at such low level.
The chamber may be substantially elliptical in cross-
section with a varying radius of curvature, the inner walls of
the upper member and base member being smoothly curved.
When the flanges of the upper and base members clamp the
flange of the intermediate member between them, this permits
ready removable attachment of the upper and base members. One
or more gaskets may be provided intermediate the flanges of the
upper member, intermediate member and/or base member.
A protective cover of transparent or translucent
material is conveniently provided above the upper member to
afford protection against physical damage, e.g. from hail
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stones. The base member may be covered on its outside by an
insulative material, e.g. of polyurethane foam.
The base member may have a downwardly depending skirt
at its outer edge for supporting the solar water heater.
The or each non-return valve in the passages may be
formed by two sheets of flat resilient material, e.g. rubber
sheeting, joined along their longitudinal edges, e.g. by
vulcanising, but not along their ends or lateral edges. One
end of the pair of rubber sheets may then be fitted over a pipe
protruding from the passage in the intermediate member. By
reason of the resilience of the pair of rubber sheets, and by
reason of their close proximity along a major portion of their
length, fluid flow from this other end through the pipe is
minimised.
The solar water heater may be mounted on a stand
which may be adjustable to permit adjustment of the angle of
inclination of the heater at different latitudes or during
different seasons of the year. In another embodiment, the
heater may be mounted on a surface by means of one or more
wedge shaped mounting members to provide a suitable angle of
inclination.
The inlet to the chamber may include a pipe forming a
blind passage and having a plurality of transversely extending
outlet apertures in the pipe to minimise disturbance of the
liquid during filling of the chamber. In another embodiment,
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the inlet to the chamber may have a deflector plate near its
mouth. The outlet to -the chamber may have a stand pipe or
pressure operated release valve to cater for expansion of the
liquid contained in the chamber.
The base member and/or upper member may be formed by
a metal pressing process.
Various embodiments of the invention are now
described by way of e~ample with reference to the accompanying
drawings, in which:-
Figure 1 shows a side elevation of a solar water
heater in accordance with the invention;
Figure 2 shows a plan view of the solar water heater
of Figure l;
Figure 3 shows a sectional view of portion of the
solar water heater;
Figure 4 shows a three-dimensional view of a non-
return valve used in the solar water heater;
Figure 5 shows a sectional view of portion of the
solar water heater mounted on a pair of wedge shaped members;
Figures 6 to 10 show schematic side elevations of
various configurations of wedge shaped mounting members used in
combination with the solar water heater; and
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Figure 11 shows a plan view of still a further
configuration of wedge shaped mounting members used with the
solar water heater.
Referring to Figures 1 to 3, reference numeral 20
generally indicates a solar water heater which includes a base
member 22 having a smoothly curved inner wall 24, an upper
member 26 which is also smoothly curved and which is adapted to
absorb radiant heat, and an intermediate member 28 of an
insulative material. Conveniently, the in-termediate member 28
is formed from two layers of fibreglass sandwiching a layer of
polyurethane foam therebetween.
The intermediate member 28 divides the solar water
heater into an upper compartment 30 and a lower compartment 32,
the lower compartment 32 being much larger than the upper
compartment 30.
The area defined between the outer surface of the
inner wall 24 of the base member 22 and a peripheral skirt 34
of the base member 22 is filled with an insulative material,
e.g. of polyurethane foam or the like. The upper member 26 is
conveniently formed as a metal pressing from copper, stainless
steel, galvanized steel, or the like and covered on its outer
surface with a matte black coating. The inner wall 24 of the
base member 22 may be moulded from a glass reinforced plastics
material.
The upper member 26, intermediate member 28 and base
member 22 each have outwardly extending peripheral flanges
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26.1, 28,1 and 22.1 respectively to permit removable attachment
of the upper and base members and sandwiching of the flange
28.1 of the intermediate member 28 between the flanges of the
upper and base members.
The upper surface of the solar water heater i8
protected by a dome-shaped protective covering 36 of a
translucent or transparent material which is hail resistant,
e.g. perspex, acrylic cabulite, or the like.
The solar water heater is filled with liquid via an
inlet connection 38 and liquid can he drawn off from the heater
via an outlet connection 40. A further outlet is provided at
42 to permit connection to an expansion pipe.
As shown in Figure 2, a plurality of passages 44 are
provided at a high level in the intermediate member 28 and a
further set of passages 46 are provided at a low level in the
intermediate member 28.
At least those passages 44 at a high level are, as
shown in Figure 3, controlled by a non-return valve 48, details
of which are shown in Figures 3 and 4. As shown in Figure 3,
the passage 44 is defined by a pipe 50 extending through and
protruding from the intermediate member 28. The non-return
valve 48 comprises a pair of rubber sheets joined together
along their longitudinal edges at 52 (see Figure 4). Ona end of
the pair of rubber sheets is fitted over the pipe 50 while the
rubber sheets at the other end, by reason of their resilience,
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are in close proximity. It has been found that this arrangement
allows flow of liquid from the pipe S0 into the lower compart-
ment 32 but reverse flow is minimised. If non-return valves
are provided in the passages 46 at a low level, they would be
reversed and extend into the upper compartment to minimise flow
of liquid from the upper compartment to the lower compartment.
As shown in Figures 1 and 3, the inner walls of the
solar water heater are smoothly curved having a varying radius
of curvature so that the chamber in which liquid is held, is
substantially elliptical in crosssection. In plan view, the
chamber can be circular as shown in Figure 2 or square or
rectangular as described.
As shown in Figure 3, the flange 28.1 of the
intermediate member 28 is clamped between the flanges 26.1 and
22.1 of the upper member 26 and the base member 22 by means of
a plurality of bolts and nuts 54. O-ring type gaskets 56
prevent leakage of the liquid from the upper and lower
compartments 30 and 32.
As shown in Figure 1 and 2, the solar water heater
can be mounted on an adjustable stand 58 so that as much as
possible of the surface area of the upper member 26 is
presented to the direct rays of the sun.
In another arrangement shown in Figures 5 to 11, one
or more wedge shaped mounting members 60 may be provided for
mounting the solar water heater 20 on a surface 62. Thus, in
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Figure 6, where the surface 62 e.g. a roof of a dwelling, is
inclined at an angle of, say, 30 , a single mounting member 60
is used so that the heater 20 is arranged at an angle of 45.
In the Figure 7 embodiment, the surface 62 is at an angle of
15, and, accordingly two mounting members 60 are used.
In Figure 8, three mounting members 6Q are used on a
flat horizontally extending surface 62.
In Figure 9, four mounting members 60 are used when
the surface 62 slopes downwardly away from the sun.
In Figure 10, three mounting members 60 are used to
mount the heater 20 on a vertical surface 62, which may, for
example, be the side wall of a building.
In Figure 11, the mounting members 60 are furthermore
rotated relative to each other to provide a tortuous mounting
for a surface 62 which does not run substantially east west.
Details of the mounting members 60 are shown in
Figure 5. As shown, the mounting members 60 have lower and
upper inwardly turned flanges 64 which are bolted together. The
lowermost flange 64 is fixed to the surface 62 via a flange 65
while the base of the solar water heater has an inwardly
directed lip 66 attached to its skirt 34 whereby the base of
the solar water heater is fitted onto the uppermost flange of
the mounting member 60. When the solar water heater is fixed
directly to a surface, a flange similar to the flange 65 is
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provided attached to its base via a countersunk screw (not
shown).
In use, while the solar water heater is exposed to
sunlight, water contained therein will be heated in the upper
compartment 30 and, by convection, will pass through the
passages 44 into the lower compartment while water in the
lower compartment will circulate into the upper compartment via
the passages 46. While the solar water heater is not exposed
to sunlight, the major portion of the liquid contained therein
is insulated by the intermediate member 28 to prevent
radiation of heat outwardly therefrom. Only the liquid
contained in the upper compartment 30 will lose heat during
such periods.
The invention provides a neat, compact solar water
heater which can be relatively inexpensively manufactured and
which minimises heat loss during periods when it is not exposed -
~to sunlight. A variety of configurations of mountings are
provided for the solar water heater to facilitate its mounting
on different surfaces. The construction of the solar water
heater is simple as the upper and base members can be formed
from metal pressings and/or moulded forms. The solar water
heater can be readily disassembled for inspection and cleaning.
It will be noted that the surfaces of the solar water heater
which in use will be in contact with water are weld-free
thereby minimising the risk of corrosion of welded joints. The
non-return valves are also of simple yet, it is believed,
effective construction and not readily susceptible to furring.
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