AU598755B2

AU598755B2 - Solar water heater

Info

Publication number: AU598755B2
Application number: AU63521/86A
Authority: AU
Inventors: Arthur Maurice Meredith
Original assignee: HEATMASTER TECHNOLOGY Pty Ltd
Current assignee: HEATMASTER TECHNOLOGY Pty Ltd
Priority date: 1985-10-03
Filing date: 1986-10-01
Publication date: 1990-07-05
Anticipated expiration: 2006-10-01
Also published as: AU6352186A

Description

598755 contaias LT)sby fand~ L COMMONWEA~fH OF;AUSTRAUIA PATENTS FOWM COMPLETE SPECiFICATION

(ORIGINAL)

6-352'/ft? FOR OFFICE USE Application Numbor: PH02742 Lodged: 03/10/85 Complete Specification-Lodged: Accepted: Published: Priority: Related Art: Cass i?2as L U 1 1- 1 iiltU t t Name of Applicant: Address of Applicant: Actual lnventom: Address for Service: TO BE COMPLETED BY APPLICANT ARTHUR MAURICE MEREDITH 45a Monash Avenue, Como, in the State of Western Australia, Commonwealth of Australia.

ARTHUR MAURICE MEREDITH Wray Associates, Primary Industry House, 239 Adelaide Terrace, Perth, W.A. 6000 complete Specification for the Invention entitled: "SOLAR WATER HEATER" The following statement is a full description of this invention, including tile best method of performing it known to me 2 THIS INVENTION relates to water heaters utilising solar energy as a source of heat.

In one form the invention resides in a water heater comprising a fluid reservoir, one or more solar panels connected to the reservoir through an outlet located in the lower portion of the reservoir and an inlet also located in the lower portion of the reservoir and a little above the outlet, the reservoir and solar panels being filled with a heating fluid, a first heat exchanger located within the lower part of the reservoir and a second heat exchanger located within the upper portion of the reservoir, said heat exchangers being connected in series with the inlet of the first heat exchanger being connected to a mains water supply line and the outlet of the second heat exchanger being connected to a hot water gas burner So.oo o delivery line, and a :aa=frl-r- h Pn t arranged to t heat the contents of the reservoir at a location between the heat exchangers to heat the upper portion of the contents of the reservoir to a predetermined temperature, SicA gcis 'ourYnex' A cCt=C to se.t. oC) p-ecA\\e\ eo-\c u t ciA e. oQSeu- ^o t VS re ote .Qvytc\ C>e According to a preferred feature of the invention the first heat exchanger has its inlet and outlet connected into the lower portion of the heat reservoir.

According to a further preferred feature of the invention the flow of fluid between the reservoir and the first heat exchanger is induced by means of a pump.

According to a further feature of the invention the flow of water is only induced when solar radiation is incident on the solar absorption means and when a desirable temperature differential exists between the fluid in the lower portion of the reservoir and the fluid in tne first heat exchanger.

Li d ISI 2a According to a further feature of the invention the reservoir is vented to atmosphere through an expansion reservoir.

i1 -3- The invention will be more fully understood in the light of the following description of one specific embodiment.

The description is made with reference to the accompanying drawings of which: Figure 1 is a schematic diagram of the embodiment; and Figure 2 is a sectional elevation of the embodiment.

The embodiment is directed to a water heater utilising solar energy as the principal heating source and gas, oil, electricity, solid fuel or some other form of energy as a secondary heat source.

The embodiment comprises a heat store in the form of a main reservoir 11 and a set of solar absorption panels 12. The set of solar absorption panels 12 are interconnected in series as shown. The main reservoir 11 is connected to the set of solar panels by a cold fluid line 13 between the lower header of the first of the series of solar panels and a lower outlet port 14 in the main reservoir 11. The hot water line 15 between the set of solar panels 12 and the main reservoir extends from the lower header of the last of the solar panels and a lower inlet port in the main reservoir 16 spaced a little above the lower inlet port 14. The inlet for the hot liquid line 15 into the main reservoir is effected through an open ended tube 15a extending axially through the main reservoir 11 and having holes in its walls at spaced intervals along its length. A pump 17 in the cold fluid line 13 causes the flow of fluid between the main reservoir 11 and the set of solar panels 13. If desired and as shown a pair of pumps may be connected in parallel to ensure back-up in the event that one of the pumps should fail. The operation of both pumps is through a selection switch 18 and ajphot=1=tzz controller 19 which ensures that either of the pumps are activated only when sufficient solar energy is incident on the photo- )e4lt-aee controller. The operation of either of the pumps 17 is further controlled through the use of a differential controller incorporated with the photovltaee- controller and which is sensitive to the temperature differential between liquid in the bottom of the main reservoir and the set of solar panels through a pair of probes 20 such that the pumps 17 will only operate when a satisfactory temperature differential exists. By virtuc of th: intcrccnncotin bt'cn t of solar panels 12 and the main reservoir the le of the contents of the main reservoir 11 eated with little stratification resulting m such unless the uppermost contents of the n reservoir have a higher temperture than the d flowing into the main reservoir Sthrough the ho uid line 15. In addition the absorption of heat rom the set of solar panels is optimised through The contents of the main reservoir 11 are vented to atmosphere through a vented expansion tank 21 which has an inlet from the mains supply 22 controlled through a Sfloat controlled valve. The expansion tank is connected via an expansion line 23 to a port 24 in the uppermost portion of the main reservoir 11.

The main reservoir 11 accommodates a secondary heat Taorce oiro.uLf94Y source in the form cf a/gas burner 25 which is mounted to Sone end and is located substantially centrally to extend Saxially into the reservoir. The innermost end of the burner chamber connects with a set of parallel axially directed exhaust tubes 26 which open into a flue 27. The operation of the gas burner is controlled by a thermostat having a sensor 28 located in the lower portion of the upper half of the main reservoir to ensure that the upper half of the contents of the main reservoir are maintained at or above a predetermined temperature.

L-7 i L ii.~ The main reservoir 11 contains a liquid which will not scale the reservoir or solar panels which is substantially non-corrosive and which has a relatively high specific heat. Such a liquid may comprise water containing anti-scaling additives and corrosion inhibiting additives.

VtgC-OyrM The h-eat'abeA water supply is heated via a::.ccon-y I aYrL- ger eonip.- j a first heat exchange coil 29 located in the lowermost portion of the main reservoir and a second heat exchanger 30 located in the uppermost portion of the main reservoir. The heat exchangers are connected in series through a connecting line 38 extending between the outlet 32 of the first heat exchanger 30 and the inlet 33 of the second heat exchanger 31. The inlet 34 of the first heat exchanger is connected to the mains water supply 22. The outlet of the second heat exchanger is connected to the hot water supply line 36 which services several hot water outlets 37. The hot water line 36 is under mains pressure and is formed as a closed loop which terminates at its other end at a junction 39 with the connecting line 38.

Heated water in the hot water line is circulated around the closed loop by means of a second pump 40 to ensure that heated water is immediately available at all hot water outlets.

A drain outlet 41 is provided at the lowermost portion of the main reservoir remote from the fluid ports therein.

In use the set of solar panels 12 serve in heating the whole of the contents of the main reservoir 11 without inducing stratification while the gas burner 25 serves in heating the upper portion of the main :.eservoir only.

Stratification of the contents of the mai:-, reservoir is induced by the gas burner 25 when the desired temperature of the upper portion of the contents of the main 6 reservoir exceeds that of the heated fluid from the set of solar panels and/or the lower contents of the main reservoir. This stratification is enhanced by location of a9 the first secondary heat exchanger 4 in the lower portion of the main reservoir by which cold water from the mains supply 22 is initially heated by the lower portion of the reservoir. As a result water flowing to the second heat exchanger 31 has been preheated to facilitate efficient consumption of the heat produced by the gas burner 25 which generally utilises a more expensive source of energy.

As a result of the embodiment a water heater is produced which utilises a solar energy as a primary heating source together with a more expensive source of energy. As a result of the embodiment the heat input into the reservoir from the absorption solar energy is maximised and the extraction of heat is such as to minimise the utilisation of the more expensive energy source. Tn Summer the solar energy may effect heating of the whole of the contents of the reservoir without the need to rely on the more expensive source of energy.

It should be appreciated that the scope of the invention need not be limited to the particular scope of the embodiment described above and in particular to the particular arrangement of components of the embodiment.

Claims

1. A water heater comprising a fluid reservoir, one or more solar panels connected to the reservoir through an outlet located in the lower portion of the reservoir and an inlet also located in the lower portion of the reservoir and a little above the outlet, the reservoir and solar panels being filled with a heating fluid, a first heat exchanger located within the lower part of the reservoir and a second heat exchanger located within the upper portion of the reservoir, said heat exchangers being connected in series with the inlet of the first heat exchanger being connected to a mains water supply line and the outlet of the second heat exchanger being connected to 9&S 'Ay-ry-\.r a hot water delivery line, and a 4 non-- ola -heat ott arranged to heat the contents of the reservoir at a location between the heat exchangers to heat the upper oC portion of the contents of the reservoir to a 0 predetermined temperature sa't as \o.e r SOw l co'r eckeO tbV 00 o oh e r e r c- ct e ct a t ZC- V, o0l, aX%- siNC> o o N o

2. A water heater as claimed in claim 1 wherein a pump ;o is provided to pump heating fluid from the reservoir to the solar panels.

3. A water heater as claimed in claim 2 wherein the 090 operation of the pump is controlled by a photo voltaic o o* controller. o o S"

4. A water heater as claimed in claim 3 wherein the operation of the pump is also controlled by a differential controller sensitive to the temperature differential 0444 between the temperature of the heating fluid in the a19 lowermost portion of the reservoir and the temperature of the heating fluid in the solar panels.

Iq 'kAL/ 0 8 A water heater as claimed in any one of the preceding claims wherein the reservoir is vented to atmosphere through an expansion reservoir.

6. A water heater as claimed in claim 5 wherein the expansion reservoir is connected to a source of water through a level control valve.

7. A water heater as claimed in any one of the preceding claims wherein the heating fluid is water containing anti-scaling additives and corrosion inhibiting additives.

8. A water heater as claimed in any one of the preceding claims wherein the hot water supply line comprises a closed loop between the upper end of the ~secondary heat exchanger and an intermediate location of O the secondary heat exchanger. f"

9. A water heater as claimed at claim 8 wherein a pump is incorporated.in the closed loop for circulating heated water therearound. A water heater substantially as herein described. DATED this twentieth day of February, 1990 ARTHUR MAURICE MEREDITH Applicant WRAY ASSOCIATES Perth, Western Australia Patent Attorneys for the Applicant.