U.S. patent application number 12/312480 was filed with the patent office on 2010-08-12 for system and method for heating water.
Invention is credited to Colin David Hook.
Application Number | 20100199973 12/312480 |
Document ID | / |
Family ID | 39401897 |
Filed Date | 2010-08-12 |
United States Patent
Application |
20100199973 |
Kind Code |
A1 |
Hook; Colin David |
August 12, 2010 |
SYSTEM AND METHOD FOR HEATING WATER
Abstract
A system for heating a liquid, such as water, the system
including a collector and a storage tank, wherein the collector and
the storage tank are fluidly coupled together via a manifold. The
collector includes a plurality of heat pipes which extend into the
manifold. Solar energy is absorbed by the heat pipes and passed to
liquid in the manifold, which in turn, is passed to the storage
tank.
Inventors: |
Hook; Colin David;
(Palmerston North, NZ) |
Correspondence
Address: |
COOPER & DUNHAM, LLP
30 Rockefeller Plaza, 20th Floor
NEW YORK
NY
10112
US
|
Family ID: |
39401897 |
Appl. No.: |
12/312480 |
Filed: |
November 14, 2007 |
PCT Filed: |
November 14, 2007 |
PCT NO: |
PCT/NZ2007/000336 |
371 Date: |
April 20, 2010 |
Current U.S.
Class: |
126/610 ;
126/635; 126/640; 126/714 |
Current CPC
Class: |
Y02B 10/20 20130101;
Y02E 10/44 20130101; F24S 60/30 20180501; F24S 10/45 20180501; F24S
90/10 20180501; F24S 10/95 20180501 |
Class at
Publication: |
126/610 ;
126/640; 126/635; 126/714 |
International
Class: |
F24J 2/42 20060101
F24J002/42; F24J 2/04 20060101 F24J002/04; F24J 2/32 20060101
F24J002/32; F24J 2/00 20060101 F24J002/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 14, 2006 |
AU |
551361 |
Claims
1. A system for heating a liquid, such as water, the system
including a collector and a storage tank, wherein the collector and
the storage tank are fluidly coupled together via a manifold.
2. The system of claim 1, wherein the collector includes a
plurality of heat pipes.
3. The system of claim 2, wherein the heat pipes are arranged to be
substantially parallel to one another.
4. The system of claim 2 or claim 3, wherein each heat pipe
includes an at least partially evacuated tube that houses at least
a first portion of a sealed riser therein.
5. The system of any one of claims 2 to 4, wherein at least a
portion of each heat pipe extends into the manifold.
6. The system of claim 5 when dependent on claim 4, wherein the at
least a portion of each heat pipe that extends into the manifold
comprises a second portion of the respective riser.
7. The system of claim 6, wherein the second portion of each riser
is in the form of a bulb.
8. The system of claim 6 or claim 7, wherein the second portion of
each said riser is configured to be oriented above the respective
first portion thereof when in use.
9. The system of any one of claims 2 to 8, wherein the manifold
comprises a conduit having a substantially constant cross-section
and a plurality of apertures in at least one wall thereof, each of
the apertures being configured to receive a respective one of the
plurality of heat pipes, such that a portion thereof is located
inside the manifold.
10. The system of any one of the preceding claims, wherein the
storage tank comprises a hot water cylinder that is oriented such
that its major axis is substantially horizontal.
11. The system of any one of the preceding claims, wherein the
manifold comprises an inlet and an outlet, wherein the manifold
outlet is fluidly coupled to a first storage tank inlet and the
manifold inlet is fluidly coupled to a first storage tank
outlet.
12. The system of claim 11, wherein the first storage tank inlet is
oriented above the manifold outlet and the first storage tank
outlet is oriented above the manifold inlet.
13. The system of 11 or claim 12, wherein the storage tank
comprises a second storage tank inlet adapted to receive liquid
from an external source.
14. The system of any one of claims 11 to 13, wherein the storage
tank comprises a second storage tank outlet for enabling hot liquid
to be drawn off from the storage tank.
15. The system of any one of the preceding claims, wherein the
storage tank comprises auxiliary heating means.
16. The system of any one of the preceding claims, wherein the
system comprises remote heating means for generating hot liquid,
the remote heating means having an inlet and an outlet.
17. The system of claim 16, wherein the remote heating means
comprises a wetback.
18. The system of claim 16 or claim 17, wherein the storage tank
comprises a generally serpentine conduit or coil housed within the
storage tank and having an inlet and an outlet.
19. The system of claim 18, wherein the remote heating means outlet
is fluidly coupled to the coil inlet, such that, in use, liquid
heated by the remote heating means flows through the coil and
provides heat to liquid held in the storage tank outside of the
coil.
20. The system of claim 19, wherein the remote heating means inlet
is fluidly coupled to the coil outlet.
21. Preferably, the coil outlet is oriented below the coil
inlet.
22. A collector configured for incorporation in the system of any
one of the preceding claims.
23. A manifold configured for incorporation in the system of any
one of claims 1 to 21.
24. A storage tank configured for incorporation in the system of
any one of claims 1 to 21.
25. A method of heating a liquid, such as water, the method
comprising providing a solar power collector in thermal
communication with a manifold and the manifold in fluid
communication with a storage tank such that, in use, solar power
received by the collector causes heat to be transferred to the
manifold and to any liquid therein, and the heated liquid then
passes to the storage tank by thermosiphoning.
26. The method of claim 25, comprising providing an electrical
heating element in the storage tank, such that, in use, liquid may
be heated thereby.
27. The method of claim 25 or claim 26, comprising thermally
coupling the storage tank to an external heating means.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to systems and methods for
heating a liquid, such as water. In particular, the invention
relates to systems and methods involving use of thermosiphoning
and/or heat pipes.
BACKGROUND
[0002] Thermosiphoning solar systems have conventionally consisted
of a collector and a water tank for storing hot water. The hot
water tank is located above the collector. As water in the
collector is heated, it expands, lowering its density and causing
it to rise up through an outlet at the top of the collector and
into the hot water tank through an inlet generally provided near
the top thereof. At the same time, colder, more dense water is
drawn into an inlet at the bottom of the collector either from an
outlet generally positioned at the bottom of the hot water tank or
from an alternative source, such as the mains water supply, another
tank, etc.
[0003] US 2006/0219237 A1 describes a thermosiphoning system with
side mounted storage tanks. The system includes a substantially
planar collector that has a plurality of heat exchange channels
(e.g. small diameter plastic tubes) that are positioned next to one
another in a parallel relationship. Headers (e.g. large diameter
plastic pipes) are provided at the top and bottom of the collector
and storage tanks (e.g. large diameter plastic pipes) are provided
on either side of the collector.
[0004] US 2006/0219237 A1 differs from earlier systems in that
tanks are provided either side of the collector as opposed to being
above the collector. As liquid is heated in the collector by solar
power, it moves upwards towards the header at the top of the
collector and then into an inlet provided at the top of each of the
storage tanks. Water from the bottom of the storage tank may enter
through one or more inlets in the header at the bottom of the
collector such that water circulates through the system. Hot water
may be utilized by pumping it through an outlet provided in the
header at the top of the collector, or through outlets provided at
the tops of the storage tanks. This water may be replenished using
an inlet provided in the header at the bottom of the collector that
is coupled to a water source such as a mains pipe.
[0005] Whilst US 2006/0219237 A1 takes some advantage of
thermosiphoning principles, pumps are still required to move hot
water to where it is required, which expend electrical energy and
complicate the system.
SUMMARY OF THE INVENTION
[0006] It is an object of the invention to provide an improved
system and/or method for heating a liquid, such as water, or at
least to provide a useful choice.
[0007] According to a first aspect of the invention, there is
provided a system for heating a liquid, such as water, the system
comprising a collector and a storage tank, wherein the collector
and the storage tank are each sealably coupled to a manifold.
[0008] Preferably, the collector comprises a heat pipe. More
preferably, the collector comprises a plurality of heat pipes.
[0009] Preferably, the heat pipes are arranged to be substantially
parallel.
[0010] Preferably, each heat pipe comprises an at least partially
evacuated tube that houses a first portion of a sealed, preferably
copper, riser therein.
[0011] Preferably, each said at least partially evacuated tube is
an at least partially evacuated glass tube.
[0012] Preferably, each said at least partially evacuated tube has
first and second ends.
[0013] Preferably, each said at least partially evacuated tube is
coupled to the manifold proximate the first end thereof, and the
second end is distal therefrom.
[0014] Preferably, a second portion of each said riser extends out
of the at least partially evacuated tube at the first end thereof
and into the manifold. Preferably, each said second portion of the
riser is in the form of a bulb.
[0015] Preferably, the second portion of each said riser is
oriented above the respective first portion thereof.
[0016] Preferably, sealing means, such as a plug, is provided
proximate the first end of each said at least partially evacuated
tube so that at least a partial vacuum is maintained therein.
[0017] Preferably, each said sealing means sealably engages an
inside wall of a corresponding said at least partially evacuated
tube and has an aperture for sealably receiving and holding a
corresponding said riser.
[0018] Preferably, each said riser contains a liquid, such as
water. More preferably, each said riser contains distilled water or
alcohol.
[0019] Preferably, the manifold comprises a conduit having a
preferably substantially square cross-section.
[0020] Preferably, the manifold comprises a plurality of
apertures.
[0021] Preferably, each of the apertures is adapted to allow the
bulb of a corresponding said riser to pass therethrough such that
the bulbs are situated inside the conduit.
[0022] Preferably, the manifold comprises an inlet and an
outlet.
[0023] Preferably, the storage tank comprises a hot water cylinder
that is oriented such that its axis is substantially
horizontal.
[0024] Preferably, the manifold outlet is fluidly coupled to a
first storage tank inlet. Preferably, the first storage tank inlet
is oriented above the manifold outlet.
[0025] Preferably, the manifold inlet is fluidly coupled to a first
storage tank outlet. Preferably, the first storage tank outlet is
oriented above the manifold inlet.
[0026] Preferably, the storage tank comprises a second storage tank
inlet adapted to receive liquid from an external source, such as
the water mains.
[0027] Preferably, the storage tank comprises a second storage tank
outlet. Preferably, the second storage tank outlet is adapted to
enable users to draw hot liquid from the storage tank, as
required.
[0028] Note that the first and second storage tank inlets and the
first and second storage tank outlets are used to denote inlets and
outlets of the same storage tank (i.e., the first and second
storage tank inlets are first and second inlets of the same storage
tank).
[0029] Preferably, the storage tank comprises auxiliary heating
means, such as an electrical heating element. The auxiliary heating
means may be used to provide additional heat to liquid in the
storage tank such as at times when there is a high demand on the
system or when there is little or no solar power available (e.g. at
night or during cloudy conditions).
[0030] Where an electrical heating element is used, preferably, the
storage tank comprises an anode for preventing corrosion to the
lining of the storage tank due to galvanic action or
electrolysis.
[0031] Preferably, the system comprises remote heating means, such
as a wetback, which may be used to generate additional hot
liquid.
[0032] Preferably, the remote heating means comprises an inlet and
an outlet.
[0033] Preferably, the storage tank comprises a generally
serpentine conduit or coil that has an inlet and an outlet.
Preferably, the inlet and the outlet are provided proximate a wall
of the storage tank and the coil is substantially housed within the
storage tank.
[0034] Preferably, the remote heating means outlet is fluidly
coupled to the coil inlet, such that liquid heated by the remote
heating means may flow through the coil and thereby provide heat to
the liquid that is held in the storage tank outside of the
coil.
[0035] Preferably, the remote heating means inlet is fluidly
coupled to the coil outlet so that liquid may return to the remote
heating means as it cools down and be reheated. Alternatively, the
remote heating means inlet may be adapted to receive liquid from an
external source so that liquid leaving the remote heating means is
replenished as opposed to simply circulating between the coil and
the remote heating means.
[0036] Preferably, the coil outlet is oriented below the coil
inlet.
[0037] Preferably, the coil inlet comprises a valve, such as a ball
valve, which enables excess pressure to be relieved.
[0038] According to second through fourth aspects there are
respectively provided a collector, a manifold or a storage tank
adapted for use in the system of the first aspect.
[0039] A fifth aspect of the invention is to use of the system of
the first aspect and/or use of one or more apparatus of the second
through fourth aspects for heating a liquid.
[0040] According to a sixth aspect, there is provided a method of
heating a liquid, such as water, the method comprising providing a
solar power collector in thermal communication with a manifold and
the manifold in fluid communication with a storage tank such that,
in use, solar power received by the collector causes heat to be
transferred to the manifold and to any liquid therein, and the
heated liquid then passes to the storage tank by
thermosiphoning.
[0041] Preferably, the method comprises providing an electoral
heating element in the storage tank, such that, in use, liquid may
be heated therein.
[0042] Preferably, the method comprises thermally coupling the
storage tank to an external heating means, such as a wetback.
[0043] Further aspects of the invention, which should be considered
in all its novel aspects, will become apparent to those skilled in
the art upon reading the following description which provides at
least one example of a practical application of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] One or more embodiments of the invention will be described
below by way of example only and without intending to be limiting
with reference to the following drawings, in which:
[0045] FIG. 1 is a schematic perspective view of an embodiment of a
system according to the invention;
[0046] FIG. 2 is a perspective view of an embodiment of the system
of the invention, similar to that of FIG. 1, with a portion removed
to aid understanding;
[0047] FIG. 3 is a cross-sectional side view of a portion of the
system of FIG. 1 or 2;
[0048] FIG. 4 is a cross-sectional view of a storage tank, such as
for use with the system of FIGS. 1 and/or 2;
[0049] FIG. 5 is an alternative cross-sectional view of the storage
tank of FIG. 4;
[0050] FIG. 6 is a schematic diagram of an alternative embodiment
of the system of the invention;
[0051] FIGS. 7A-7C show embodiments of fixings that may be used
with embodiments of the invention; and
[0052] FIG. 8 is a flow diagram of an embodiment of the method of
the invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0053] FIGS. 1 and 2 show system 1 according to slightly varying
embodiments of the invention, which do not materially differ.
System 1 includes a collector 10, a manifold 12 and storage tank
14. Storage tank 14 may be referred to as a hot water cylinder and
is abbreviated hereinafter to hwc.
[0054] Collector 10 comprises a plurality of heat pipes 16 which
are preferably arranged substantially parallel to each other to
form a preferably substantially planar collector of solar power.
FIG. 3 is a cross-sectional side view of a heat pipe 16 of
collector 10 and manifold 12 that shows the internal configuration
thereof and the presently preferred manner in which they are
coupled together. Heat pipe 16 comprises tube 30 which houses a
first portion 31 of sealed or closed, preferably copper, riser 32
therein. Tube 30 is preferably an at least partially evacuated
glass tube so that the sun's rays may pass therethrough and impinge
on riser 32, thereby causing riser 32 to heat up, but heat loss by
conduction from riser 32 is reduced.
[0055] Riser 32 is at least partially filled with a liquid,
preferably alcohol, so that as riser 32 heats up, this heat is
transferred to the liquid therein. Moreover, liquid in first
portion 31 of riser 32 heats up and may vaporise. As it does so, it
moves towards second portion 33 of riser 32, second portion 33
preferably being in the form of a bulb and above first portion
31.
[0056] Manifold 16 comprises a conduit having a preferably
substantially square cross-section, although other cross-sections,
including generally circular, are also within the scope of the
invention. Manifold 16 comprises a plurality of apertures 34, each
of which is adapted to receive and sealably engage a corresponding
tube 30. Preferably, manifold 12 sealably engages tube 30 at, or at
least proximate to, a first end 35 thereof so that tube 30 does not
significantly extend into the space inside manifold 12 and inhibit
flow of liquid therethrough, as will be described in more detail
below.
[0057] Preferably, second portion 33 of each riser 32 extends out
of tube 30 at first end 35 thereof and into manifold 12. Sealing
means, such as plug 36, is provided proximate first end 35 of each
said at least partially evacuated tube so that at least a partial
vacuum is maintained inside tube 30. Each plug 36 sealably engages
an inside wall of a corresponding tube 30 and has an aperture for
sealably receiving and holding a corresponding riser 32.
Preferably, each plug 36 is configured as the sole support for the
corresponding riser 32.
[0058] The extension of risers 32 into manifold 12 enables the
transfer of heat from first portion 31 of riser 32 to second
portion 33 and then to the inside of manifold 12. The configuration
of second portion 33 of riser 32 as a bulb improves the rate of
heat exchange with a liquid that may be present in manifold 12.
Insulation 37 may be provided to reduce heat loss from manifold 12
to the surroundings.
[0059] Referring back to FIGS. 1 and 2, manifold 12 comprises inlet
38 and outlet 39 which enable liquid to enter through inlet 38,
flow through manifold 12 and exit through outlet 39. During passage
of the liquid through manifold 12, the temperature of the liquid
rises as the liquid is heated by the bulbs of risers 32.
[0060] Hwc 14 is preferably substantially cylindrical and oriented
such that its axis is substantially horizontal. Hwc 14 is fluidly
coupled to manifold 12 such as by conduits or pipes so that liquid,
generally water, may flow therebetween. In particular, manifold
outlet 39 is fluidly coupled to first storage tank inlet 40 and
manifold inlet 38 is fluidly coupled to first storage tank outlet
41.
[0061] Preferably, first storage tank inlet 40 is oriented above
manifold outlet 39. While not such in such a configuration in the
Figures, preferably, the first storage tank inlet 40 is located
towards the top of hwc 14. Preferably, first storage tank outlet 41
is oriented above manifold inlet 38.
[0062] Preferably, hwc 14 comprises second storage tank inlet 42
(see FIG. 2) which is adapted to receive liquid from an external
source, such as the water mains. Hwc 14 also comprises second
storage tank outlet 43. Second storage tank outlet 43 is adapted to
enable users to draw hot liquid from hwc 14, as required. For
example, second storage tank outlet 43 may be fluidly coupled to
one or more hot water taps (not shown) using appropriate piping. As
hot liquid is drawn off through second storage tank outlet 43,
liquid stored in hwc 14 is replenished through second storage tank
inlet 42.
[0063] Operation of the invention will now be described. Rays from
the sun pass through tubes 30 and heat risers 32 and the liquid
therein. As the liquid in risers 32 heats, it expands and may
vaporise. The heated liquid and/or vapours become more buoyant and
rise into second portion 33 of riser 32 inside manifold 12 i.e.,
the bulb. A liquid, generally water, is present in manifold 12 and
is heated as it comes into contact with the bulbs. As the liquid in
the manifold 12 heats up, it expands and passes out of manifold
outlet 39 and into hwc 14 through first storage tank inlet 40. If
there is no external draw operating on system 1 through second
storage tank outlet 43 (e.g. no one is running a hot water tap),
cooler liquid from the bottom of hwc 14 is drawn into manifold 12
through manifold inlet 38, where it is in turn heated, thereby
circulating the liquid between manifold 12 and hwc 14. If there is
an external draw on system 1, cooler liquid from an external
source, such as the water mains, enters hwc 14 via second storage
tank inlet 42 so that as hot liquid is drawn from system 1, it is
replenished. The liquid in hwc 14 may then pass to manifold 12 to
be heated. Alternatively, the external source of liquid may be
fluidly coupled to manifold 12 as opposed to hwc 14. Thus, liquid
may be replenished in manifold 12 as opposed to hwc 14.
[0064] Due to the particular vertical arrangements of each of the
components of system 1, system 1 may operate on the basis of
thermosiphoning and does not require the use of pumps. However, the
present invention does not preclude the use of pumps in combination
with any of the embodiments thereof.
[0065] Preferably, hwc 14 comprises auxiliary heating means, such
as electrical heating element 45. Electrical heating element 45 may
be used to directly provide additional heat to liquid in hwc 14
such as at times when there is a high demand on system 1 or when
there is little or no solar power available (e.g. at night or
during cloudy conditions). Electrical heating element 45 may
comprise, or be coupled to, a thermostat so that heating by
electrical heating element 45 is controlled to prevent overheating.
In embodiments including electrical heating element 45, preferably,
hwc 14 comprises anode 46 for preventing corrosion to the lining of
the storage tank due to galvanic action or electrolysis. Anode 46
may be comprised of magnesium or aluminium and preferably has a
higher potential than the material it is protecting, namely a
lining of hwc 14, which acts as a cathode. Anode 46 is sacrificed
or dissolved in order to prevent corrosion of hwc 14.
[0066] Electrical heating elements and anodes are well known in the
art and the skilled man would be able to modify and/or select an
appropriate element and/or anode depending on the desired
application. The invention is therefore not limited to the
particular type or configuration of element and/or anode shown but
it is intended to include any such modifications.
[0067] As shown in FIGS. 1 and 2, hwc 14 comprises coil 50. Coil 50
is shown in more detail in FIGS. 4 and 5. Coil 50 comprises a
generally serpentine conduit having inlet 51 and outlet 52.
Preferably, inlet 51 and outlet 52 are provided proximate a wall of
age to receive 14 and coil 50 is contained within hwc 14. Coil
inlet 51 is preferably arranged to be above coil outlet 52. Each
serpentine coil of coil 50 comprises a substantially linear section
followed by an arcuate section and then another substantially
linear section. Each linear section, as one moves from coil inlet
51 to coil outlet 52, has a downward gradient. In a preferred
embodiment, each linear section has a length of between 2 and 2.5 m
and preferably falls by between 6 and 12 millimetres over that
length, so as to facilitate thermosiphoning. Coil 50 may be secured
using plates 47 and fixings 48 (e.g. nuts and bolts).
[0068] Referring to FIG. 6, coil 50 is fluidly coupled to a remote
heating means, such as wetback 60. Wetback 60 preferably comprises
a furnace which may be used to remotely heat a liquid, such as by
burning solid fuel. Wetback 60 comprises outlet 61 and inlet 62.
Wetback outlet 61 is fluidly coupled to coil inlet 51, such that
liquid heated by wetback 60 may flow through coil 50 and thereby
provide heat to the liquid that is held in hwc 14. Coil outlet 52
is preferably fluidly coupled to wetback inlet 62 so that after the
liquid has passed through coil 50 and cooled down due to its use in
heating the relatively cooler liquid inside hwc 14, it is
recirculated to wetback 60 for reheating. Additionally or
alternatively, wetback 60 may be adapted to receive liquid from an
auxiliary source, such as the water mains, so that liquid leaving
wetback 60 is otherwise replenished.
[0069] Preferably, coil inlet 51 is situated at a height greater
than that of wetback outlet 61. Preferably, coil outlet 52 is at a
height greater than that of wetback inlet 62. Preferably, wetback
outlet 61 is above wetback inlet 62.
[0070] A pressure relief valve or vent, such as ball valve 63, may
be used to relieve excess pressure proximate coil inlet 51.
[0071] Also shown in FIG. 6 is the connection of system 1 to
external liquid supply 65, such as the water mains. Other supplies
of liquid may be used as would be apparent to one of skill in the
art, such as reservoirs, separate containers or tanks, wells etc.
External liquid supply 65 is fluidly coupled to second storage tank
inlet 42, such as by suitable piping. External liquid supply 65 may
further be coupled to wetback 60. Preferably, this coupling
comprises isolation valves 66 with pressure reducing valve 67
fluidly coupled therebetween. This arrangement of valves enables
flow of liquid in the correct direction and also allows for the
relief of any excess pressure.
[0072] FIGS. 7A through 7C show various fittings that may be used
with system 1. Referring to FIG. 7A, there is shown tray 70. Tray
70 is adapted such that hwc 14 may be seated thereon. Tray 70 may
include tray outlet 71 which is adapted to allow liquid leaking
from hwc 14 and the various inlets and outlets thereof to be
captured in tray 70 and passed through tray outlet 71 to an
appropriate drain.
[0073] FIG. 7B shows means 72 for retaining hwc 14 in position.
Means 72 preferably comprises an angled bracket. Means 72
preferably works in combination with retaining means 73 of FIG. 7C,
such that rotational or sliding movement of hwc 14 is prevented.
Thus, hwc 14 is held between means 72 and first face 74 of
retaining means 73. Second face 75 of retaining means 73 is
preferably adapted to fixedly hold manifold 12 in position.
[0074] Various elements of system 1 may be provided with
insulation. For example, hwc 14 may be provided with heat
insulation as would be apparent to one of skill in the art.
[0075] According to preferred embodiments of the invention,
collector 10, manifold 12 and hwc 14 are adapted for installation
outside, such as on the roof of a building. However, according to
an alternative embodiment, hwc 14 may be installed inside a
building, such as in the roof cavity thereof, with the conduits
from manifold 12 appropriately extended. Thus, at least hwc 14 may
be remotely located from collector 10 and/or manifold 12.
Preferably, the generally upward gradient is maintained from the
free ends of heat pipes 16 to manifold 12 and then to first storage
tank inlet 40.
[0076] A preferred method of the invention is set out in FIG. 8.
The method depends on whether or not there is solar power
available, or moreover, whether there is sufficient solar power
available. If there is, the liquid in heat tubes 16 is heated and
the risers then heat the liquid in manifold 12. As the liquid is
heated in manifold 12, it expands and becomes more buoyant, causing
it to pass to hwc 14. Then, depending on whether there is an
external drain on hwc 14, such as through use of a hot water tap
coupled to second storage tank outlet 43, liquid from an external
source, such as the water mains, may pass into hwc 14. In either
case, colder liquid from hwc 14 passes to manifold 12 through a
manifold inlet 38 as warmer liquid exits through manifold outlet
39.
[0077] If there is not sufficient solar power available, one or
both of two additional methods may be used. Firstly, electrical
heating element 45 may be switched on to heat liquid in hwc 14 as
required. Alternatively or additionally, wetback 60 may be
activated to heat liquid therein, such as by using a furnace. The
heated liquid expands and becomes more buoyant, causing it to rise
to coil inlet 51. The liquid flows through coil 50 until it reaches
coil outlet 52 where it is passed back to wetback 60 for reheating.
As the liquid flows through coil 50, it heats liquid held in hwc
14.
[0078] It should be noted that any combination of the three methods
of heating may be used. For example, in times of high demand, all
three methods may be used simultaneously.
[0079] Dimensions included in any of the Figures are preferred
dimensions and are not intended to be limiting.
[0080] It should be noted that various changes and modifications to
the presently preferred embodiments described herein will be
apparent to those skilled in the art. Such changes and
modifications may be made without departing from the spirit and
scope of the present invention and without diminishing its
attendant advantages. It is therefore, intended that such changes
and modifications be included within the present invention.
* * * * *