AU2006252311A1 - Underground Heat Exchanger - Google Patents

Description

22-DEC-2006 14:18 A J PARK 64 9 3566990 Regulation 3.2

AUSTRALIA

PATENTS ACT, 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventor: Address for service in Australia: Invention Title: Details of Associated Provisional Application: TOKO INDUSTRY COMPANY LIMITED AND GEO ENERGY NEW ZEALAND LIMITED Toko Hashitnoto A J PARK, Level 11, 60 Marcus Clarke Street, Canberra ACT 2601, Australia Underground Heat Exchanger 2006900080 The following statement is a full description of this invention, including the best method of performing it known to us.

COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-00 14:18 A J PARK 64 9 3566990 P.06 -2o The present invention relates to an underground heat exchanger. More particularly C' but not exclusively it relates to an underground heat exchanger, having an improved d) coefficient of performance (COP) of energy usage, that can be applied to a building.

The temperature of soil at a depth greater than 10 m corresponds to the average C'i 5 yearly temperature of the area. 'IThis means that the soil at this depth is cool in summer (relative to ambient surface temperature) and warm in the winter (relative to ambient surface temperature). For example, in western parts of Japan, the yearly mean temperature c is 15 0 C, ranging from 32 0 C in summertime to -2°C in wintertime. Therefore, at a depth of V) 10 m or more the temperature of the soil remains at Generally it is necessary to dig very deep in order to increase the heat transfer area o for underground heat exchangers. Current heat exchange apparatus make use of this constant ground temperature by extending into the ground to a depth of 50 to 100 m.

Heat is collected by a heat pump system by recycling water or liquid solvent in a long pipe that enters down to this depth. However, the temperature differential between the liquid and soil is small. This method of providing air conditioning requires digging to a great depth which is very costly. The COP of this existing technology is about The coefficient of performance (COP) is an index that describes the efficiency of an air-conditioner, refrigerator or heat pump. It gives the ratio of heating or cooling provided by a heat pump (or other electric machine) to the energy consumed by the system under designated operating conditions. The higher the COP, the more efficient the system. For example, with a COP of 10, this means that a system generates 10 kW of energy when it consumes 1 kW.

It is an object of the present invention to provide an underground heat exchanger with an improved coefficient of performance (COP), which overcomes or at least ameliorates some of the abovementioned disadvantages or which at least provides the public with a useful choice.

Other objects of the invention may become apparent ftrom the following description which is given by way of example only.

In a first aspect the invention is an apparatus providing a ducted fluid flow below ground where the ducted fluid during its ducted passage transfers heat to or from the ground through the or a duct wall(s), therc being as a consequence of lower heat transfer through the walls(s) near and/or above ground level and greater heat transfer COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:19 A J PARK 64 9 3566990 P.07 -3- 0 o through the wall(s) at a greater depth than those said wall(s) near and/or above the ground, a net temperatute change to the fluid as a consequence of such transfer.

0 ~In one embodiment of the invention the apparatus hasinsulation (whether in contact or not) about the apparatus at least at and/or above the ground surface.

C, 5 Preferably the duct wall is of a conductive material defining a chamber or conduit into which there is, for the passaging fluid, both an inlet and an outlet.

Preferably one of said inlet and outlet is a conduit inlet or outlet feeding into or out M of a larger conduit, the larger conduit (hereinafter "outer conduit") (at least over the heat Ni kn exchange zone) being thermally conductive.

Ni 1NO Preferably said inlet is formed between the inner wall of said outer conduit and the oouter wall of an inner conduit that is disposed at least in part within said outer conduit, and wherein the inner conduit defines the oudet.

Preferably said outer conduit extends to approximately 5 m under the ground surface.

In a farther aspect the invention is an heat exchange apparatus for, or suitable for, heat exchange between a fluid and the ground, said apparatus comprising an outer conduit of heat conductive material installed, or installable, to a depth of approximately 5 m under the ground surface, an inner conduit disposed at least in part within the outer conduit, and wherein the two conduits co-act, or are adapted, to define a fluid flow locus of a fluid to be heat exchanged that involves flow between the conduits.

In one embodiment of the present invention said apparatus includes insulation (whether in contact or not) about the outer conduit at least at and/or above the ground surface- Preferably the ground has at least three temperature zones being at least a first zone located at or adjacent the surface being that ground that is disturbed by ambient air temperature, a second zone located below said first zone and extendable to a depth of approximately 5 m from the surface, and a third zone located below said second zone and being defined by having an increased annual mcan temperature compared with said second zone in summex, and a decreased annual mean temperature compared with said second zone in winter COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:19 A J PARK 64 9 3566990 P.08 -4hetIn a further aspect the invention is an heat exchange apparatus for, or suitable for, heat exchange between a fluid and at least one zone of ground, said ground comprising at least three temperature zones, and said apparatus comprising: an outer conduit providing a ducted fluid flow below ground, said outer conduit having at least a first locus of reduced heat transfer adapted for positioning substantially about that area of the ground at or adjacent the surface en3 of the ground that is disturbed by ambient air temperature (hereinafter "first zone"), and (ii) a second locus of increased heat transfer adapted for positioning IN00 oabout a second zone in the ground, said second zone at a depth c'-i below said fiast zone, yet above the depth of a third zone in the ground, said third zone having an increased annual mean temperature compared with said second zone in summer, and a decreased annual mean temperature compared with said second zone in winter, an innet conduit providing a ducted fluid flow disposed at least in part within the outer conduit.

In a further aspect the invention is an a heat exchange apparatus installed in the ground for, or suitable for, heat exchange between a fluid and at least one zone of ground, said ground comprising at least three temperature zones, and said apparatus comprising an outer conduit providing a ducted fluid flow below ground, said outer conduit having at least a locus of reduced heat transfer (hereinafter "first locus") positioned substantially about that area of the ground at or adjacent the surface of the ground that is disturbed by ambient air temperature (hereinafter "first zone"), and (ii) a locus of increased heat transfer (hereinafter "second locus') positioned about a second zone in the ground, said second zone at a depth below said first zone, yet above the depth of a third zone in the ground, said third zone having a increased annual mean temperature compared with said second ;,one in summer, and a decreased annual mean temperatre compared with said second zone in winter, an inncr conduit providing a ducted fluid flow disposed at least in part within the outer cotduit.

COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:19 A J PARK 64 9 3566990 P.09 o In one embodiment of the invention the heat exchanger is in situ.

Preferably said first zone of ground is to a depth of approximately 2 m from the C. surface. Preferably said second zone is between approximately 2 rn to approximately 5 in from the surface.

Preferably the fluid inlet is formed between the inner wall of the outer conduit and the outer wall of the inner conduit.

Preferably the base of the outer conduit is sealed, and the base of the inner conduit is nnot sealed.

tfl Preferably said apparatus contains condensed water at the base of said conduits and INO 10 wherein the base of the inner conduit penetrates into said condensed water, yet where said 0 oinner conduit does not extend to the base of the outer conduit.

Preferably the fluid is air.

In one embodiment of the invention the apparatus has insulation (whether in contact with the outer conduit or nor) to substantially insulate the first zone.

In one embodiment of the invention the apparatus said insulation extends from approximately ground level to approximately 0.3-1 m under ground.

In one embodiment of the invention the apparatus said insulation extends from approximately ground level to approximately 0.5 m under ground.

In one embodiment of the invention the apparatus said insulation insulates said outer conduit to a depth from approximately 0.5 to approximately 1 m.

In one embodiment of the invention the apparatus the thickness of the insulation is approximately 300-500 mm.

Preferably said surface insulating material is a foaming plastic. Preferably thickness of the foaming plastic is approximately 500 ram.

In one embodiment of the invention the apparatus said apparatus includes insulating boards placed above and/or adjacent the surface of said apparatus. Preferably said boards have a thickness of approximately 50 mm. Preferably said insulating boards extend to a depth of approximately 300-500 mm about said apparatus In one embodiment of the invention said apparatus has at least one vertical fin attached to the exterior surface of said outer conduit. Preferably the fins are disposed dircumferentially about said outer conduit. Preferably said fins are formed from aluminium. Preferably the fins have a thickness of approximately 10 ram. Preferably said fins extend substantially the length of said second zone. Preferably said material having good heat conduction filled around said outer conduit or part thereof. Preferably said COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:20 A J PARK 64 9 3566990 -6- Va omaterial having good heat conduction is selected from the group comprising a mneral, solid metallic material or granular metallic material. Preferably said material having good heat conduction is filled ksound said outer conduit or part thereof by dense illing.

Preferably said material having good heat conduction is filled around said outer conduit in Cl 5 the said second zone. Preferably said material having good heat conduction is coal.

In one embodiment of the invention said apparatus has a COP of between 9-15.

Preferably said apparatus has a COP in wintertime is between 11.3-13.

Cfl Preferably said apparatus has a COP in summertime is between 12.1-14.2.

IPreferably said conduits ate pipes.

V.Q 10 In another aspect of the present invention consists there is provided an 0 o underground beat exchanger comprising: a heat exchanger defined as a substantially vertical double pipe (preferably coaxia) extending from at least the ground surface (preferably to approximately S m under ground level), said double pipe having: an outer pipe having a closed bottom end and open upper end, an inner pipe positioned at least in part in said outer pipe, a space between said outer and inner pipes adapted to receive the heat exchange medium, an inner pipe space defining the space within said inner pipe; surface insulating material, at or adjacent ground level, around said outer pipe.

Preferably the heat exchange medium is air. In a different embodiment of the present invention the heat exchange medium could be liquid solvent, water etc).

In one embodiment of the present invention said surface insulating material insulates said outer pipe from approximately ground level to a depth of approximately 0.3-1 m.

In one embodiment of the present invention said surface insulating material insulates said outer pipe from a depth of from approximately ground level to approximately 0.5-1 m.

In a forther aspect of the invention there is provided an underground heat exchanger comprising an underground double pipe, vertically constituted by an outer pipe and an inner pipe for heat exchange to the air from the geothermal energy. Said outer pipe having its upper end opened and its bottom end dosed, and an inner pipe having both ends opened. The air flows into the annular part from the top and exchanges heat with the underground soil. This heat exchanger is buried down to 5 m from the ground level and is COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:20 A J PARK 22-DC-26 120 J PRK64 9 3566990 P.11 -7o insulated with a surface insulating matertial from aipproximately ground level to approximately 0.5-1 mndeep around the outer pipe.

C) Preferably the tippet end of the outer pipe is opened and the bottom end of the 0 outer pipe is closed. Preferably the inner pipe has both of its ends opened.

c-i $In one embodiment of the present invention the air flow is into the space formed between the inner and outer pipes where heat exchange occurs with the underground soil, prior to the air flow passing up through the inner pipe.

MC Preferably the hear exchanger extends from at least the ground surface to 5 mn under tfl ground level.

Va0 10 Preferably the heat exchanger is insulated from ground level to between 0.3-1 in o deep around the outer pipe by filling the surface with insulating material.

ci Preferably said surface insulating material is a foaming plastic.

In one embodiment of the present invention said heat exchanger comprises -a vertical fin attached to said outer pipe. Preferably said pipe is attached to said outer surface of said outer pipe at a distance of between 2 to 5 m from the ground surfatce.

In one embodiment of the present invention a material having good hear conduction is filled around said underground heat exchanger or part thereof. Preferably said material having good heat conduction is selected from the group comprising a ininerat solid metallic material or granular metallic material. Preferably said material h1aving good heat conduction is filled around said underground heat exchanger by dense filling. More preferably said material having good he-at conduction is filled around said beat exchanger to a depth of between 2 to Sm.

Preferably said material having good heat conduction is coal.

Preferably said he-at exchanger contains condensed water at the bottom of the outer pipe and -wherein the bottom of the inner pipe dips ito said condensed water.

Preferably said heat exchanger is further insulated by insulating boards placed over and/or adjacent the upper part of the hear exchanger.

In one embodiment of thte present invention the underground heat exchanger has a COP of between 9-15S. Preferably the unde".ground hear exchanger has a COP in wintertime of between 11.3-13. Preferably the underground heat exchanger has at COP in sumnmadtie is between 12.1-14.2.

In a further aspect of the invention there is provided the use of a heat exchanger of the present invention.

COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-26 14:20 A J PARK 64 9 3566990 P.12 -8o In a further aspect of the invention there is provided a method of installing an c underground heat exchanger that utilises heat conduction to or from a ground, comprising the steps of: installing an outer conduit into the ground to a depth of approximately 5 m (C 5 under the ground surface, installing an inner conduit such that it is disposed at least in part within the outer conduit, C refilling earth about said outer conduit.

tl In a further aspect of the invention there is provided a method of installing an VO 10 underground heat exchanger that utilises heat conduction to or from a ground, said 0 ground comprising at least three temperature zones, and said method comprising the following steps of: installing an outer conduit into the ground, said outer conduit having at least a locus of reduced heat transfer (hereinafter "first locus") positioned substantially about that area of the ground at or adjacent the surface of the ground that is disturbed by ambient air temperature (hereinafter "first zone"), and (ii) a locus of increased heat transfer (hereinafter "second locus") positioned about a second zone in the ground, said second zone at a depth below said first zone, yet above the depth of a third tone in the ground, said third zone having an increased annual mean temperature compared with said second zone in summer, and a decreased annual mean temperature compared with said second zone in winter (iii) installing an inner conduit such that it is disposed at least in part within the outer conduit, refilling earth about said outer conduit.

Preferably an insulating material is placed about an upper portion of said outer conduit (whether in direct contact or not).

Preferably an said inner and outer conduits are held in a spaced relationship to provide ducted passages defined by at least the space formed between the inner surface of the outer conduit and the outer surface of the inner conduit and within the inner conduit.

In a further aspect of the invention there is provided a method of providing air conditioning, that utilises heat conduction to or from the ground, comprising the steps of: COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:21 A J PARK 64 9 3566990 P.13 -9-

IN

o installing an outer conduit into the ground to a depth of approximately 5 m 0 under the ground surface, installing an inner conduit such that it is disposed at least in part within the 0outer conduit, such that said inner and outer conduits are held in a spaced relationship to provide ducted passages defined by at least the space formed between the inner surface of the outer conduit and the outer surface of the inner conduit (hereinafter "inlet duct"), and within the inner conduit (hereinafter "outlet duct"), ci pumping air into said inlet duct, ci 10 retrieving said air via outlet duct, pumping said retrieved air into an area to be air conditioned.

ci Preferably said method includes the step of providing at least one or more fius on the outer surface of said outer conduit, said fins extending from at least 2 in under the ground surface.

Preferably said method includes the step of providing a material having good heat insulation about the lower portion of said outer conduit- Preferably said method includes the step of providing insulation about the upper portion of said outer conduit.

In a further aspect of the invention there is provided a method of extxacting heat for uptake into a moving fluid, said method involving ducting the fluid below ground in a first conduit and retrieving that fluid in a conduit defined by a surround of a second conduit, the arrangement being such that the first conduit is adapted to be in heat transfer commiuication, yet that part of said first conduit adjacent and/or near the ground sutface is insulated.

According to a further aspect of the invention there is provided a substantially as hexcin described and with reference to any one or more the accompanying drawings and/or examples.

Other aspects of the invention may become apparent from the following description, which is given by way of example only and with reference to the accompanying drawings.

As used herein the term "air" can refer to ordinary air 21% 78% N 2 or a gas or mixture thereof, and which can be at ambient atmospheric pressure or otherwise.

As used hercin the term "and/or" means "and" or or both.

The term "comprising" as used in this specification and claims means "consisting at least in part of". When interpreting statements in this specification and claims which COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:21 A i PPR< 22-EC-00614:1 PJ PRK64 9 3566990 P.14 include that tenn, the features, prefaced by that term in each statement, a 1 1 need to be present but other features can also be present. Related terms such as "ccomprise"~ and "comprised" are to be interpreted in the same manner.

0 To thosc skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are CC) not intended to be in any sense limiting.

The invention will now be described by way of example only and with reference to the drawings in whic-h: o Figure 1 is an illustration of the temperature profile of a single day in summertime, Figure 2 is an illustration of a heat exchanger of a preferred embodiment showing insulation of the surface ground area, Figure 3 is an illustration, of the underground temperature profile with the surface ground insulation of Figure I comparing the non-insulation, Figure 4 is -an illustration showing insulation around the underground heat exchanger, Figure 5 is an illustration showing insulation on the outer surface of the underground heat exchanger, Figure 6 is an illustration showing a fin on the outer surface of the underground heat exchanger, Figure 7 is an illustration showing a material having good heat conduction filled around the underground heat exchanger, and Figure 8 is an illustration of the overall heat exchanger.

An underground he-At exchanger of the present invention can be applied to a building such as detached housing, collective housing or a building as a whole.

The titne delay of heat transfer of the solar energy at a depth of 5 m fromn ground level can be used to cool a building in summer (owing to the lower temperature of the ground at 5 to below ground relative to the outside ambient air), and to provide he-at in winter (owing to the higher temperature of the ground at 5 m below ground relative to the outside ambient air). It is important to note that the temperature of the ground down to a depth of 5 in is cooler in s ummer than a depth of 10 mn and deeper. Likewise, in winter the temperature of the ground down to 5 in is higher than the mean temperature at a depth of in and deeper.

COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 2-DEC-206 14:21 A J PARK 64 9 3566990 -11

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O Therefore, it is more efficient, both in terms of heat efficiency and the cost of NC digging a shallower hole, to dig down only 5 n from the ground surface.

SHowever, because the outdoor or ambient temperature has an effect on the Stemperature of the ground down to a certain depth (about 2 the apparatus of the ,i 5 present invention uses the heat transfer from this depth ~2 m) down to 5 m. i.e. in order to provide a high energy efficiency system it is better to avoid heat transfer at shallower depths owing to the disturbance in the temperature at shallower depths caused Cc by the outdoor or ambient temperature.

V The efficiency of the heat transfer system is enhanced by reducing or avoiding heat transfer at the shallower depths by the use of insulation, and increasing or promoting heat o transfer at depths of 2 m and deeper.

C Figure 1 shows the underground temperature profile for one day. It can be seen that the influence of the outdoor or ambient temperature is significant on soil to a depth of in. Thus, the temperature of the ground to a depth of 0.5 m changes greatly whereas the temperature of the ground at a depth from 0.5 m to 2 m declines exponentially.

Although the underground temperature is almost constant for ground at a depth of 6 m and deeper, the temperature of the ground at a depth of 2-5 m is actually lower than the mean temperature of ground at a depth of 6 m and below in summertime, and is conversely higher in wintertime. To have efficient heat transfer it is necessary to prevent heat transfer from between ground level 7 to the depth of 2 m regardless of whether or not the underground heat exchanger extends down to 5 m or deeper.

Figure 2 is an illustration of an underground heat exchanger 1 showing surface insulation 2 of the surrounding surface area of the underground heat exchanger 1. As seen in Figure 2 there is an outer pipe 3 having a dosed bottom end and an open upper end.

Inside of the outer pipe 3 is an inner pipe 4 having both ends open. Preferably both said pipes are coaxial. It should be appreciated that other arrangements of a double pipe system could be used. For example, wherein the pipes are not coaxially arranged.

When in use the heat exchange medium enters the top of the heat exchanger 5 into the space between the outer and inner pipes. As the heat exchange medium moves deeper in depth down the apparatus 1 it transfers heat with the surrounding ground. Once at the bottom of the outer pipe 3, the heat exchange medium moves up through the inner space of the inner pipe 4 as shown by the arrows 6.

Preferably the heat exchange medium is air, although it should be appreciated that it could be any other heat transferable medium such as a liquid based substance, or a gas COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:22 A J PARK 64 9 3566990 P.16 -12- (compressed or not). Furthermore, working fluid could be used and could be changed C, depending on whether heating or cooling depending on the efficiency characteristics of the working fluid.

0As seen in Figure 2 there is surface insulation material 2 to help insulate the underground heat exchanger I from heat exchange at shallower ground depths.

Figure 3 shows the underground temperature profile of the heat exchange apparatus 1 with insulation 9 and without insulation CC) The surround ground surface area of the underground beat exchanger I can be covered by the insulating material 2 such as an insulating board. Alternatively, it is possible to dig arouind the underground heat exchanger to a depth of approximately 300 to 500 mm owhich is then filled with an insulating material.

Ci When the underground heat exchanger 1 is covered by insulating board, the area of the insulation must be wider than the 300 to 500 mm that is required when using the dig and fill methodology. This is because heat diffusion comes from the uncovered area. It is better to dig 300 to 500 mm and fill with an insulating material.

Figure 2 is an illustration of the latter case of dig and fill.

Various types of insulation can be used for the surface insulation. For example, a foaming plastic, a natural mineral, a mineral incinerated material, etc are suitable for use. A foaming plastic is especially suitable. It should be appreciated that any other suitable insulating material could be used.

If using a foaming plastic and/or a diatomite as the insulation material, then 300 mm thicless is sufficient for interrupting the influence of the temperature difference from the soil above 2 m in depth. Generally it is uneconomical to increase the thickness of the insulation beyond 500 mm.

Figure 3 shows the underground temperature profile for an apparatus having the insulation formed from 500 mm foaming plastic. The solid line is with insulation 9, the dotted line shows "without insulation" When comparing the apparatus with insulation (solid line) to that of without insulation 10 (dotted line), the effective pipe length for heat transfer is more than 1 m.

Furthermore, the COP is improved by a factor of 1.4.

Figure 4 shows the use of further insulation 2 to cover the underground heat exchanger to help reduce the heating/cooling in summer/winter respectively of the input air 5 into the underground heat exchanger I.

COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:22 A J PARK 64 9 3566990 P.17 -13- O As for the above, a foaming plastic, a natural mineral, an incinerated material, are Ssuitable for use as the insulating material. Preferably the insulation is formed from a 0 foaming plastic. It is sufficient to install insulating board of 50 mm thickness to a depth of 0 between 300 to 500 mm around the underground heat exchanger 1.

Cl 5 In summer the temperature of the ground to a depth of between 0.5 to 1 m is higher than the yearly mean temperature of the ground. Likewise, in winter the temperature of the ground to a depth of between 0-5 to 1 m is lower than the yearly mean temperature of the ground. Therefore, because an aluminium alloy (which is an excellent conductor), is Cl used for the pipe material, the heat transfer at a depth of up to approximately between C'l 10 to 1 m below surface level can be adversely affected leading to a consequential reduction in Sthe efficiency of the underground heat transfer apparatus 1.

0 Figure 5 shows an underground heat exchanger 1 with the upper suface of the outer pipe 3 covered by insulation 11.

This insulation 11 is inserted to a depth of about 0.5 to 1 m to surround outer pipe 3 of the underground heat exchange.

Preferably the outer pipe is covered with insulation material to a depth of at least m, to reduce or prevent any undesirable heat exchange from that ground influenced by the outdoor/ambient temperature. It is generally uneconomical when this insulation exceeds a depth of 1 m.

Preferably the thickness of the insulation is about 100 to 200 mm.

A thickness of at least 100 mm is necessary to insulate the outer pipe 3. It is generally uneconomical to insulate the outer pipe beyond 200 mm in thickness.

Although underground temperature distribution does not change significantly, in this case the effective length of a pipe that contributes to the heat exchange is increased.

Furthermore, the COP is improved by a factor of between 2 to 3- Figure 6 shows an underground heat exchanger 1 having fins 12 installed on the surface of the outer pipe 3 of the underground heat exchanger 1.

The fins 12 extend the heat exchange area of the pipe apparatus. The fin or fins 12 are attached onto the outer pipe 3 extending in the direction of the pipe (vertically) by any known method. e.g. welding, moulding etc.

The efficiency of thc underground heat exchanger 1 improves most when the fin or fins 12 are installed at a depth of between 2 to 5 m, as at this depth the ground is cooler in summer and warmer in winter than the mean temperature of the ground.

COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:22 A J PARK 64 9 3566990 P. 18 -14- Va O Preferably the point(s) where the fin or fins 12 attach/contact to the outer pipe 3 are 0 thicker to allow for better conduction of heat.

O The use of a fin or fins 12 makes it possible to increase the surface area of the heat

C)

Sexchanger contacting with the ground by about a factor of between 2 to 3.

Cl 5 While the ground has an almost unlimited heat transfer capacity, as well as being able to maintain a fairly constant temperature at depths below 2 m, there is a problem with heat conduction in soil that contains mineral oxides.

Therefore, it is important to ensure that the underground heat exchanger 1 is placed Cl into soil that does not reduce the efficiency of the heat exchanger. In other words, it is CN 10 advantageous to increase the heat-conductivity of the ground.

SThis can be done by filling the area around the underground heat exchanger 1 with a 0, material that has good heat conduction properties.

As shown in Figure 7, some ground around the underground heat exchanger 1 is excavated and filled with a material having good heat conduction 13. This material 13 could be any material that exhibits good heat conduction properties, such as, for example, a mineral, metal slug, etc.

Preferably the material 13 having good heat conduction properties is a carbon-based material. Such material is reasonably cheap compared to other metals and does not corrode or change when in the ground. Both lump-shaped and grain-shaped material is suitable. These can be filled densely around the underground heat exchanger 1.

Such material 13 being granular in form can be used to fill in the gaps around the underground heat exchanger 1. If desired, soil could also be used for filling the gaps.

It is advantageous to fill such material 13 (having good heat exchange properties) thickly around the underground heat exchanger 1 between a ground depth of 2 to 5 m.

This ensures that this ground, which is cooler in summertime and warmer in winter, has good heat transference properties.

Another example of a cheap alternative of a material 13 with good heat conduction properties is coal. Coal has a heat conduction of 1.3 W/mK compared to that of 0.6 W/mK in soil.

The installation of a heat exchanger of the present invention can be performed by first excavating a hole, inserting the heat exchanger outer pipe or outer conduit (whether integral with the inner conduit or not). The installation can be performed by installing the fins first and then lowering the apparatus into the hole, or fixing the fins to the outer pip once the heat exchanger pipes are in the hole. The material with good conduction can then COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:23 A J PARK 64 9 3566990 P.19

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o be filled about the heat exchanger and any insulation installed. The hole is then backfilled 0 to fill any gaps.

SExample 1 Figure 8 shows an underground heat exchanger 1 for use with a building.

c 5 The insulation 2 installed around the underground heat exchanger 1 was installed at a thickness of 200 mm to a depth of 0.5 m. A suitable insulator is Styrofoam. This was also installed above the underground heat exchanger 1. Furthermore, insulation 11 was also installed around the upper surface of the outer pipe to a depth of between 0.5 to 1 m.

tn The material with increased heat exchange properties 13 was filled around a part of N 10 the underground heat exchanger at a depth of from 2 to 5 m from ground level. As o mentioned previously, coal can be used. Lumps of approximately 100 mm are suitable to be piled around the underground heat exchanger 1. Gaps can be filled with smaller sized particles or with soil.

In this embodiment of the present invention the underground heat exchanger 1 was installed to a depth of 5 m.

On the outside surface (aluminium pipe) of the underground heat exchanger, 5 to aluminium fins (width 100 mm X length 3000 mm, situated from 2 m to 5 m from the ground level) are fixed by welding and installed into the ground.

As the outdoor air is introduced to the top of the annular part of the double pipe underground heat exchanger 1, it passes down through the gap formed between the outside pipe 3 and the inner pipe 4. Heat transfer occurs as the air passes down the outside pipe and when it reaches the inner pipe 4 (formed from polyethylene) it passes into the building.

In summer, the cooled air is introduced indoor, and in winter the warmed air is introduced indoor. The air is introduced by a fan. The consumed energy is only the electricity use to power the fan and a condensate discharge pump. A condensate discharge pump intermittently takes care of any condensed water in the heat exchanger. The COP is easily computed from this with temperature humidity data of introduced air.

Condensed water is collected at the bottom of the outside pipe. The introduced air hits this water and the OH-ion in the condensed water (so called minus ion) are generated and sent indoor. Some toxic substance or irritants such as VOC, pollen, powdered dust etc, are absorbed in to the water from the air and discharged outside.

COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:23 A J PARK 64 9 3566990 -16-

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0 Example 2 (Refer drawing 4) ~The vertical underground double pipe heat exchanger has an outer pipe 3 with a diameter of 250 mm. This outer pipe 3 is made of aluminium and has a length of 4.5 m.

SThe inner pipe is made of polyethylene and has a diameter 150 mm. The inner pipe is 5 installed down to 4.5 m from the ground level.

Air is introduced to the top of the heat exchanger (into the space formed between thie outer and inner pipes) at a rate of 730 m 3 /hr. In summertime, introduced ambient air C of 32.3 0 C is cooled to 26.8 0 C. In wintertime, introduced ambient air of 4.1°C is heated to ci V) 10°C. The recorded COP in summertime is 11.3 and 12.1 in wintertime.

In western parts of Japan, the temperature varies at the surface of the ground in o summertime by about 8°C and in wintertime by about 4*C. In order to avoid the influence of this variation, as shown in Figure 5, the upper part of the underground heat exchanger from ground level to a depth of approximately 0.5 m is coveted by 50 mm thick insulation (Styrofoam). The outer surface of the apparatus 1 becomes nearer to the soil temperature at a depth of 05 m- With this improvement, the summertime ambient intake air of 32.3°C is cooled to 26.0°C (an improvement from 26.8°C) which corresponds to a 15% improvement with a COP of 13.0. In wintertime, the ambient intake air of 4.1°C is heated to 11.0°C (an improvement from 10.0°C), which corresponds to a 17% improvement with a COP of 14.2.

Improved efficiency is seen with the installation of fins 12 to the outer surface of the underground heat exchanger 1- In this example, 8 fins were installed, having a width of 100 umn, a length of 700 mm and a thickness of 10 mm. These were welded to the outside surface of a 250 mm diameter aluminium pipe. With this improvement, the summertime ambient intake air of 32,3 0 C is cooled to 26.3°C which corresponds to a 9% improvement with a COP of 12.3.

As shown above, when comparing to the existing heat exchange systems that extend to a depth of from 50 to 100 tn, this invention can significantly improve an installation costs by reducing the digging depth down to 5 mn as well as improving their efficiency.

In addition to energy savings, this invenion can contribute to reducing global warming by helping reduce carbon dioxide emrnissions- COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:23 A J PARK 64 9 3566990 P.21 -17- Va o Example 3: Use in industry 0 Cl Such an invention can be used for the following.

As an air-conditioner for all types of building.

0 Cooling the hot exhaust gas from an air-conditioner.

Cooling (or heating) liquid (water) or gas (ait) which are available for industry use, Where in the foregoing description reference has been made to elements or integers C having known equivalents, then such equivalents are included as if they were individually set forth.

Va 10 Although the invention has been described by way of example and with reference to 0 particular embodiments, it is to be understood that modifications and/or improvements C l may be made without departing from the scope or spirit of the invention.

COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date (Y-M-d)2006-12-22

Claims (20)

1. 22-DEC-2006 14:23 A J PARK 64 9 3566990 P.22 -18- O 0 o WHAT WE CLAIM IS: C 1. An apparatus providing a ducted fluid flow below ground where the ducted fluid during its ducted passage transfers heat to or from the ground through the or a duct 0 wall(s), there being as a consequence of lower heat transfer through the walls(s) near and/or above ground level and greater heat transfer through the wall(s) at a greater depth than those said wall(s) near and/or above the ground, a net temperature change to the fluid as a consequence of such transfer. 2. An apparatus of claim I having insulation (whether in contact or not) about the Sapparatus at least at and/or above the ground surface. 3. An apparatus of either claim 1 or 2 wherein the duct wall is of a conductive material O defining a chamber or conduit into which there is, for the passaging fluid, both an inlet and an outlet. 4. An apparatus of any one of claims 1 to 3 wherein one of said inlet and outlet is a conduit inlet or outlet feeding into or out of a larger conduit, the larger conduit (hereinafter "outer conduit") (at least over the heat exchange zone) being thermally conductive. An apparatus of claim 4 wherein said inlet is formed between the inner wall of said outer conduit and the outer wall of an inner conduit that is disposed at least in part within said outer conduit, and wherein the inner conduit defines the outlet. 6. An apparatus of either claim 4 or 5 wherein said outer conduit extends to approximately 5 m under the ground surface. 7. A heat exchange apparatus for, or suitable for, heat exchange between a fluid and the ground, said apparatus comprising an outer conduit of heat conductive material installed, or installable, to a depth of approximately 5 m under the ground surface, an inner conduit disposed at least in part within the outer conduit, and wherein the two conduits co-act, or are adapted, to define a fluid flow locus of a fluid to be heat exchanged that involves flow between the conduits. 8. An apparatus of claim 7 having insulation (whether in contact or not) about the outer conduit at least at and/or above the ground surface. 9. An apparatus of claim 7 wherein said ground has at least three temperature zones being at least a first zone located at or adjacent the surface being that ground that is disturbed by ambient air temperature, COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:24 A J PARK 64 9 3566990 P.23 -19- \O o a second zone located below said first zone and extendable to a depth of Ci approximately 5 m from the surface, and a third zone located below said second zone and being defined by having an 0 increased annual mean temperature compared with said second zone in summer, and a decreased annual mean temperature compared with said second zone in winter A heat exchange apparatus for, or suitable for, heat exchange between a fluid and at least one zone of ground, said ground comprising at least three temperature zones, and C said apparatus comprising Ci 10 an outer conduit providing a ducted fluid flow below ground, said outer o conduit having at least S(i) a first locus of reduced heat transfer adapted for positioning substantially about that area of the ground at or adjacent the surface of the ground that is disturbed by ambient air temperature (hereinafter "first zone"), and (ii) a second locus of increased heat transfer adapted for positioning about a second zone in the ground, said second zone at a depth below" said first zone, yet above the depth of a third zone in the ground, said third zone having an increased annual mean temperature compared with said second zone in summer, and a decreased annual mean temperature compared with said second zone in winter, an inner conduit providing a ducted fluid flow disposed at least in part within the outer conduit. 11. A heat exchange apparatus installed in the ground for, or suitable for, heat exchange between a fluid and at least one zone of ground, said ground comprising at least three temperature zones, and said apparatus comprising: an outer conduit providing a ducted fluid flow below ground, said outer conduit having at least a first locus of reduced heat transfer positioned substantially about that area of the ground at or adjacent the surface of the ground that is disturbed by ambient air temperature (hereinafter "first zone"), and (ii) a second locus of increased heat transfer positioned about a second zone in the ground, said second zone at a depth below said first zone, yet above the depth of a third zone in the ground, said third zone COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:24 A J PARK 64 9 3566990 P.24 Va o having an increased annual mean temperature compated with said C second zone in summer, and a decreased annual mean temperature o compared with said second zone in winter, C) 0 an inner conduit providing a ducted fluid flow disposed at least in part within l 5 the outer conduit. 12. An apparatus of either claim 10 or 11 wherein said heat exchanger is in situ. 13. An apparatus of any one of claims 10 to 12 wherein said first zone of ground is to a depth of approximately 2 m from the surface. NCl 14. An apparatus of any one of claims 10 to 13 wherein said second zone is between CN 10 approximately 2 m to approximately 5 m from the surface. An apparatus of any one of claims 4 to 14 wherein the fluid inlet is formed between C the inner wall of the outer conduit and the outer wall of the inner conduit 16. An apparatus of any one of claims 4 to 15 wherein the base of the outer conduit is sealed, and the base of the inner conduit is not sealed. 17. An apparatus of claim 16 wherein said apparatus contains condensed water at the base of said conduits and wherein the base of the inner conduit penetrates into said condensed water, yet where said inner conduit does not extend to the base of the outer conduit. 18. An apparatus of any one of claims 1 to 17 wherein the fluid is air. 19. An apparatus of any one of claims 7 to 18 having insulation (whether in contact with the outer conduit or not) to substantially insulate the first zone. An apparatus of claim 19 wherein said insulation extends from approximately ground level to approximately 0.3-1 m under ground. 21. An apparatus of claim 20 wherein said insulation extends from approximately ground level to approximately 0.5 m under ground. 22. An apparatus of claim 20 wherein said insulation insulates said outer conduit to a depth from approximately 0.5 to approximately 1 m.
2. 23. An apparatus of any one of claims 20 to 22 wherein the thickness of the insulation is approximately 300-500 mm.
3. 24. An apparatus of any one of claims 20 to 23 wherein said surface insulating material is a foaming plastic. An apparatus of claim 24 wherein the thickness of the foaming plastic is approximately 500 mm. COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:24 A J PARK 64 9 3566990 21 O 26. An apparatus of any one of claims 1 to 25 having insulating boards placed above Sand/or adjacent the surface of said apparatus. 0 27. An apparatus of claim 26 wherein said boards have a thickness of approximately r mm. Cl 5 28. An apparatus of either claim 26 or 27 wherein said insulating boards extend to a depth of approximately 300-500 mm about said apparatus
4. 29. An apparatus of any one of claims 4 to 28 having at least one vertical fin attached to the exterior surface of said outer conduit Cl 30. An apparatus of claim 29 having 5 to 10 fins disposed circumferentially about said Cl 10 outer conduit. o 31. An apparatus of either claim 29 or 30 wherein said fins are formed from aluminium. 0 32. An apparatus of any one of claims 29 to 31 wherein the fins have a thickness of approximately 10 mm.
5. 33. An apparatus of any one of claims 29 to 32 wherein said fins extend substantially the length of said second zone.
6. 34. An apparatus of any one of claims 4 to 33 wherein a material having good heat conduction is filled around said outer conduit or part thereof. An apparatus of claim 34 wherein said material having good heat conduction is selected from the group comprising a mineral, solid metallic material or granular metallic material.
7. 36. An apparatus of either claim 34 or 35 wherein material having good heat conduction is filled around said outer conduit or part thereof by dense filling.
8. 37. An apparatus of any one of claims 34 to 36 wherein said material having good heat conduction is filled around said outer conduit in the said second zone.
9. 38. An apparatus of any one of claims 34 to 37 wherein said material having good heat conduction is coal.
10. 39. An apparatus of any one of claims 1 to 38 having a COP of between 9-15. An apparatus of any one of claims 1 to 38 wherein its COP in wintertime is between 11.3-13. 41, A heat exchange apparatus of any one of claims 1 to 38 wherein its COP in summertime is between 12.1-14.2.
11. 42. An apparatus of any one of claims 40 to 41 wherein said conduits are pipes.
12. 43. A heat exchange apparatus of claim 42 wherein said pipes are formed from aluminium. COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 2;2-DEC-2006 14:25 A J PARK 64 9 3566990 P.26 -22- O 44. In a further aspect of the invention there is provided the use of an apparatus of any 0 Cl one of claims 1 to 43. U 45. A method of installing an underground heat exchanger that utilises heat Sconduction to or from a ground, comprising the steps of: C 5 installing an outer conduit into the ground to a depth of approximately 5 m under the ground surface, installing an inner conduit such that it is disposed at least in part within the outer conduit, c refilling earth about said outer conduit. Cl 10 46. A method of installing an underground heat exchanger that utilises heat 0 conduction to or from a ground, said ground comprising at least three temperature zones, C' and said method comprising the following steps of: installing an outer conduit into the ground, said outer conduit having at least a first locus of reduced heat transfer positioned substantially about that area of the ground at or adjacent the surface of the ground that is disturbed by ambient air temperature (hereinafter "first zone"), and (ii) a second locus of increased heat transfer positioned about a second zone in the ground, said second zone at a depth below said first zone, yet above the depth of a third zone in the ground, said third zone having an increased annual mean temperature compared with said second zone in summer, and a decreased annual mean temperature compared with said second zone in winter (iii) installing an inner conduit such that it is disposed at least in part within the outer conduit, refilling earth about said outer conduit.
13. 47. A method of either claim 45 or 46 wherein insulating material is placed about an upper portion of said outer conduit (whether in direct contact or not).
14. 48. A method of any one of claims 45 to 47 wherein said inner and outer conduits are held in a spaced relationship to provide ducted passages defined by at least the space formed between the inner surface of the outer conduit and the outer surface of the inner conduit and within the inner conduit.
15. 49. A method of providing air conditioning, that utilises heat conduction to or from the ground, comprising the steps of: COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22 22-DEC-2006 14:25 A J PARK 64 9 3566990 P.27 23 o(1) installing an outer conduit into the ground to a depth of approxinately 5 m 0 under the ground surf-ace, U(2) installing an inner conduit such that it is disposed at least in part within the 0 outer conduit, such that said iner -and outer conduits Are held in a spaced relationship to provide ducted passages defined by at least the space formed between the inner surface of the outer conduit and the outer surface of the inner conduit (hereinafter "inlet duct"), and within the inner conduit (hereinafter "outlet duct"), Cl(3) pumping air into said inlet duct, Nl 10 retrieving said air via outlet duct, pumping said retrieved air into an area to be air conditioned-
16. 050. A method of any one of dlaim 45 to 49 including the step of providing at least one or more fins on the outer surface of said outer conduit, said fins extending from at least 2 m under the ground surface.
17. 51. A method of any one of claims 45 to 50 including the step of providing a material having good heat insulation about the lower portion of said outer conduit.
18. 52. A method of any one of claims 45 to 51 including the step of providing insulation about the upper portion of said outer conduit.
19. 53. A method of extracting heat for uptake into a moving fluid, said method involving ducting the fluid below ground in a first conduit and retrieving that fluid in a conduit defined by a surround of a second conduit, the arrangement being such that the first conduit is adapted to be in heat transfer comnmuncation, yet that part of said first conduit adjacent and/or near the ground surface is insulated.
20. 54. A he-at exchanger substantially as herein described and with reference to any one or more the accompanying dratwings and/or examples. COMS ID No: SBMI-05758059 Received by IP Australia: Time 12:27 Date 2006-12-22