AU2005100720A4

AU2005100720A4 - Heat exchange apparatus

Info

Publication number: AU2005100720A4
Application number: AU2005100720A
Authority: AU
Inventors: Kerry Glen Frankcombe; Mark William Tremellen
Original assignee: KEMARK Pty Ltd
Current assignee: KEMARK Pty Ltd
Priority date: 2004-09-06
Filing date: 2005-09-06
Publication date: 2005-10-06
Anticipated expiration: 2013-09-06

Description

0 Title N HEAT EXCHANGE APPARATUS )Field of the Invention S 5 The present invention relates to a heat exchange apparatus particularly, although not exclusively, a heat exchange apparatus suited to heating and storage oof liquids, such as employed in hot water systems for domestic or commercial purposes.

0 S 10 Discussion of Background Art 0 O Current water heating systems, particularly those configured for use with a pressurised supply of water, typically employ a metallic storage tank which functions as a pressure vessel. The requirement for pressure vessels, including pressure tight seals for inlets and outlets together with structural rigidity, result in a relatively bulky and costly tank constructed of metal. The fabrication of current heat exchange systems, which generally employ a copper coil to carry pressurised water, is labour intensive and relatively expensive. The copper coil is disposed within a metallic storage tank, which is generally also constructed of copper to permit fixing of the coil therein by brazing. These systems are also difficult to repair, especially when the cost of repairs can amount to almost the same as purchase of a replacement tank and coil unit.

Summary of the Invention The present invention aims to provide an alternative to existing arrangements for heating liquids, including for supply of hot water.

In one broad form the invention resides in a heat exchange apparatus including: a storage tank for a primary heating liquid, the tank having an inner wall, an outer wall spaced from the inner wall and a removable lid, said storage tank formed from a heat resistant plastics material; and a coil for carrying a pressurised secondary liquid, the coil supported within the storage tank for immersion in the primary heating liquid and formed from a pressure resistant heat conductive material.

o Suitably the primary heating liquid is water, which may be conveniently Csourced from a mains pressure supply to fill the storage tank. The primary heating liquid may be circulated to a remote heating device and/or a heating device, such as an electrical resistance heating element, may be disposed within the tank.

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o 5 If required, an insulating material may be disposed in the space provided between the inner wall and outer wall of the storage tank. The insulating material 0may be composed of foamed plastics, such as polyurethane. Alternatively, the space is filled with air for insulating purposes.

oPreferably the storage tank has a body formed in one piece by rotational moulding techniques, and may be composed of a UV-stabilised polyethylene.

0 O The inner wall of the body suitably includes a taper to facilitate release from the mould. Most preferably the storage tank includes an inlet pipe and an outlet pipe integrally moulded into the body for circulating the primary heating liquid to a remote heating device.

Preferably the coil is formed from metallic tubing, suitably composed of copper. If required, the tubing of the coil could be formed from a fibre reinforced plastics or composite material. An inlet to the coil is arranged for connection to a mains pressure supply and an outlet from the coil discharges the heated secondary liquid at mains pressure.

The coil is suitably supported by support members disposed within the tank.

In one particularly preferred arrangement, the coil is supported from the lid and the inlet and the outlet thereof each penetrate the lid such that, when the lid of the storage tank is removed from the body, the coil may be conveniently withdrawn from said tank. Alternatively the coil may be suitably supported within the storage tank by a frame. The frame may be provided with a flanged upper edge for seated engagement with the upper end surface of the storage tank. The engagement between the frame and upper edge of the tank is such that upon engagement of the lid a liquid tight seal is formed. Suitably the frame is formed integral with the lid.

In a second aspect of the invention, there is provided a liquid heating system including a heat exchange apparatus as described above wherein the remote heating device comprises a solar collector through which the primary heating liquid is selectively circulated. A thermostatically controlled pump may be provided to effect circulation of the primary heating liquid.

The liquid heating system may further comprise an electric resistance C heating element disposed within the storage tank and actuated by a thermostat when the primary heating liquid falls below a predetermined threshold temperature.

Alternatively, the liquid heating system may include a gas burner associated with a O 5 thermostat and arranged for heating the secondary liquid after exit from the coil outlet.

0 Brief Details of the Drawings O In order that this invention may be more readily understood and put into V 10 practical effect, reference will now be made to the accompanying drawings illustrate 0 O preferred embodiments of the invention, and wherein: FIG. 1 is sectional side elevation view of a heat exchange apparatus of a first embodiment of the invention; FIG. 2 is a top plan view of the heat exchange apparatus of the first embodiment with a lid removed; FIG. 3 is a perspective view of the exterior of the heat exchange apparatus of the first embodiment; FIG. 4 is a detailed side elevational view of a lid for the heat exchange apparatus; FIG. 5 is a detailed side elevational view of a lid sealing arrangement of a second embodiment; FIG. 6 is a perspective view of a coil support leg; FIG. 7 is a perspective view of a coil support fame of a further embodiment of the invention; FIG. 8 is a detailed side elevational view of the coil support frame of FIG 7; and FIG. 9 is a bottom plan view of the coil support frame of FIG 7.

Description of the Preferred Embodiments A heat exchange apparatus 100 of a first embodiment is illustrated in FIGs 1, 2 and 3 of the drawings. The apparatus includes a storage tank 101 having a cylindrical body with an inner wall 102 and an outer wall 103 that is rotationally moulded in one piece from a heat resistant plastics material, here a UV-stabilised polyethylene. The inner wall 102 is tapered from one end in order to facilitate release from a mould during formation. The storage tank 101 further includes a lid 104 for releasable attachment over an open end portion of the cylindrical body at the upper portions of the walls. The inner wall 102 is spaced from the outer wall 103, suitably by approximately 40 mm to 50 mm, to form an annular insulating space 105 therebetween. The space 105 is here filled with a foamed polyurethane

IND

S 5 in order to improve insulating properties of the tank 101.

The storage tank includes an inlet or return pipe 106, an outlet pipe 107 and oan overflow pipe 108 that are integrally moulded into the body. The inlet and outlet pipes allow for circulating a primary heating liquid 109 contained in the tank to a Oremote heating device, here a solar collection panel (not shown). Circulation of the S 10 primary liquid 109 is effected by a thermostatically controlled pump (not shown), 0 O wherein thermostats are located both in the storage tank 101 and in the solar panel.

A 110 coil comprising a coiled 18m length of copper tubing of 0.5 inch (12.5 mm) diameter is arranged for immersion in the primary heating liquid 109 to heat the secondary liquid carried through the coil. The coil 110 is supported by three (3) locating legs 111.1, 111.2, 111.3 which are attached to the interior surface of the lid 104 by moulded mounting points 114. As shown in FIG. 6, each supporting leg 111 is an elongate member having a plurality of arcuate notches 112 distributed along its length for receiving respective turns of the coil 110. Locating lugs 113 are provided on the interior surface of a closed end portion 102.2 of the interior wall 102.

The coil includes an inlet end 116 and an outlet end 117 which penetrate the lid 104 through wedge shaped flanges 118, as depicted in the detailed view of FIG.

4. The inlet end of the coil is coupled to a mains pressure water supply, (typically 1000 kPa to 1400kPa) via a high pressure non-return (HPNR) valve 120, which water comprises the secondary liquid to be heated. The valve includes an auxiliary outlet 121 for connecting to a 3/8 inch (9.5 mm) diameter fill line 115 provided for filling the storage tank 101 and allowing topping up to the level of the overflow 108, as required. The flanges 118 are arranged to lock the conduits into the lid 104 in order to resist leakage or contamination of the primary heating water 109 in the tank 101.

The heat exchange apparatus 100 of the present embodiment further includes an electrical resistance heating element 123 powered from the 220-240V mains supply via a thermostatically controlled cut-out switch 124. In this arrangement a further thermostat may be employed in the solar collector (not shown) in order to control a pump for circulating primary heating water 109 from the tank to the solar collector for further heating when sufficient solar radiation is )incident on the collector.

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O 5 Systems utilising the heat exchange apparatus of the invention may alternatively include a separate heating device, such as a gas fuelled burner, Olocated downstream of the secondary liquid outlet 117.

SIn FIG. 5 there is depicted a lid sealing arrangement for a storage tank 201 O of a second embodiment of the invention, which tank is composed of a heat V 10 resistant plastic material having an inner wall 202 and an outer wall. The lid 204 0 O includes an axially extending tongue or lip 205 which is arranged for cooperation with a gasket 206 disposed in a channel 207 provided in an radial end surface 208 of the body of the storage tank bridging said inner and outer walls. In this embodiment the space 209 provided between the inner wall and outer wall of the storage tank 201 is filled with air. In a similar manner to the tank of the first embodiment, a number of fasteners such as screws, are employed to retain the lid in place.

FIG. 7 depicts an alternative arrangement for supporting the coil 110 within the in the primary heating liquid 109. In this instance the support member is in the form of a frame 300 having a flanged upper edge 301 for seated engagement with the upper end surface 208 of the storage tank.

The frame 300 is also cylindrical in this further embodiment and includes a plurality of slots 302 provided within the main body 303 of the frame 300. The slots 302 form a number of shelves 304 for supporting the turns of the coil 110 as illustrated in FIG 8. The slots 302 not only expose a portion of each turn of the coil 110 to the primary heating liquid they also allow ingress of the primary heating liquid into the support frame 300.

To further facilitate the flow of the primary heating liquid into the support frame 300 and about the coil 110 the frame is provided with a perforated base 305 as shown in FIG. 9.

It will be appreciated that a rotationally moulded storage tank composed of a heat resistant plastics material is relatively simple and inexpensive when compared with metallic tanks. Further, the plastic storage tank need not be a pressure vessel 6 0 and the removable lid allows simple and convenient repair and/or replacement of Cl the heat exchange coil composed of a pressure resistant, heat conductive tubing.

It is to be understood that the above embodiments have been provided only by way of exemplification of this invention, and that further modifications and

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S 5 improvements thereto, as would be apparent to persons skilled in the relevant art, are deemed to fall within the broad scope and ambit of the present invention odescribed herein.

Claims

3. The heat exchange apparatus of claim 1 or claim 2 wherein an insulating material is provided within the space between the outer and inner wall.
4. The heat exchange apparatus of any one of the preceding claims wherein the coil is supported by at least one support member disposed within the storage tank. The heat exchange apparatus of any one of claims 2 to 4 wherein the storage tank has a body formed in one piece from a foamed plastics material, and wherein: the heating element is an electrical resistance heating element actuated by a thermostat; said remote heating device comprises a solar collector; the coil is formed from metallic tubing; and said primary heating liquid is circulated through said storage tank by a thermostatically controlled pump. Dated this SIXTH day of SEPTEMBER 2004 Kemark Pty Ltd by PIZZEYS Patent and Trade Mark Attorneys