C ROSS-REFE RENC E

[00011 This application claims priority from U nited States Provisional Patent Application No. 61/536.331 fi led September 1 9. 201 I .

FI LD OF THE INV ENTION

[000 J The present invention relates to an energy transfer unit and a method of constructing such an energy transfer unit.

SUMMARY OF THE INVENTION

|0003| hnergy transier units arc well known and commonly used to transfer energ in the form of heat from one medium to another. As such they are generally referred to as heat exchangers. Such units are used in many industrial and commercial processes and are designed to meet the particular operating conditions of those processes.

[0004] Energy transfer units are used extensively in HVAC (heating, ventilating and air conditioning) applications where they must operate at high efficiencies and at the same time be relati vely economical to produce. One particular HVAC application arises in geothermal heating and cooling systems i n which a heat exchanger is an integral part of exchanging energy between a ground source and a fluid circ u lating between the ground source and a heat pump. The ground source is a thermal reservoir that may be a body of water, such as a lake, river or stream, or may be the ground itsel f at a depth that prov ides a substantially un iform temperature.

|0005] The heat exchangers presently used in geothermal applications may be as simple as a pipe buried w ithin the ground or submerged in a lake, or may be a mesh of smal ler pipes interconnected to a manifold. The effectiveness of the heat exchanger determines to a large extent to the overall e fficiency of the heating and cooling system, but the form of the heat exchanger has been maintained as inexpensive as possible despite the inefficiencies that such an arrangement introduces.

[ 0006J In the Applicant ^' s co pending application, Internationa! Application No.

PCT/CA20 1 1 /000846. publ i shed as WO 201 2/009802. there is di sclosed an arrangement of energy transfer unit in which heat exchange cores formed from spirally wound smal l bore tubing, referred to as capi l laries, are located with in an external housing and a Ho of water induced through the housing to increase the effic iency of the heat transfer. This arrangement has proven highly effective and has introduced signi ficant efficiencies to the overall system. The efficiencies within the energy transfer unit have made increased thermal capac ities possib le wi thin a compact overall envelope. However, such increased capacity has in turn made the control of flow with in the housing more complex over a range of operating conditions. The manufacturer of the heat exchange core itself is however labour intensive and therel ^' ore relative ly expensi ve,

[00071 It is an object of the present invention to provide an energy transfer unit in which the above disadvantages are obviated or mitigated.

[00081 In general terms, one aspect of the present invention provides an energy transfer unit hav i ng one or more modules. Kach of the modules has a support structure to support a capillary spirally wound between an inlet header and an outlet header. The modules may be stacked one above the other, with the headers interconnected to prov ide a common inlet and a common outlet for the modules. The capillaries are arranged in parallel between the in let and outlet. The heat exchanger may be sized to the particular requirements by selecting the appropriate number of modules.

100091 Preferably, each modu le has a frusto conical shell with a support structure integrated with the shell to support spiral ly wound capillaries. The frusto conical shells may be stacked one above the other in spaced relationship to provide a passage between adjacent shells and to promote flow between the shel ls and over the capillaries retained between the shells.

[0 10| In another aspect there is provide an energy transfer unit having a heat exchange core and a baffle juxtaposed over the core to direct fluid from a a heat source radial ly relative to the core.

|001 1 j Preferabl , the baffle in inclined to the direction of flow of fluid, and as a further preference, the baffle directs the fl uid to a chim ney. B RI EF DESCRI PTION OF THE DRAW INGS

[ 012J Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:

10013 J Figure 1 is front elevation of an energy transfer unit:

|0014 | Figure 2 is a section on the line N - II of Figure I ;

(00151 Figure 3 is an enlarged view of a portion of the energy transfer unit shown in Figure 2:

[00161 Figure 4 is a further enlarged view of a portion of the structure shown i n Figure 3:

[0017] Figure 5 is a view on the line V - V of Figure 3:

[0018J Figure 6 is a plan view of the energv transfer unit show n in Figure 1 according to an example embodiment:

[<)019| Figure 7 is a plan view of the energy transfer unit shown i n Figure I according to another example embodiment;

[0020| Figure 8 is a schematic representation showing the assem bly of energy transfer unit of Figure 1 .

[0021 ] Figure 9 is a section of an alternativ e embodiment of the energy transfer u nit of figure 2, and

[0022] Figure 1 0 is an enlarged vie of the embod iment of figure 9.

[0023] Figure I I is a sectional view of a further em bodiment of energy transfer un it.

J0024] Figure 1 2 is a view from belo of one of the modules show n in f igure 1 1 .

[0025] Figure 1 is a perspective view of a further embodiment of an energy transfer unit.

[0026] Figure 1 4 is a perspective vie o an energy transfer unit used with i n the unit of Figu re 1 3.

[0027J Figure 1 is a vie on the l ine XV-XV of Figure 1 .

[0028] Figure 1 6 is a side elevation in the direction o f the arrow A of Figure 14.

[0029] Figure 1 7 is a plan view o f the unit shown in Figure 14. [00301 Figure 13 is an under view of the unit shown in Figure 14.

[00311 Figure 19 is the enlarged view of a component utilized in the energy transfer unit of Figure 15.

[0032] Figure 20 is the section on an enlarged scale on the line XX-XX of Figure 14. and

[0033] Figure 21 is a schematic illustration of the installation of the heat exchange unit shown in Figure 13 w ithin a body of water.

DETAILED DESCRIPTION OF THE INVENTION

[0034| Referring therefore to Figure 1. an energy transfer unit generally indicated at 10. has a fluid inlet 12 and a fluid outlet 14. The inlet 12 and outlet 14 are connected to respective pipes 1 , 18 that in turn are connected to a heat pump in a known manner. One example of such an arrangement is shown in Figure 1 and the accompanying description of PCX publication WO 2012/009802, the contents of w hich are incorporated herein b reference. Λ particularly beneficial way of connecting the energy transfer unit 10 to a heat pump is shown in co pending application. U.S. Provisional Application No.61 523,698. the contents of which arc incorporated herein by reference.

[00351 The energy transfer unit 10 is formed from a number of modules 20. indicated individually as 20a, 20b, 20c.20d. that are stacked one above the other to provide a multi layered body to the energy transfer unit 10. Λ base 22 extends across the lower most of the modules 20d and a icthcr assembly 24 is secured to the base 22. The tether assembly 24 includes a ballast 26 and a pair of tie lines 28 that allow the energy transfer unit 10 lo he secured in location in a heat source, for example in a body of water. A tlared collar.29. is secured to the upper module 20a to promote flo through the heat exchanger 10.

[0036| Each of the modules 20 is of similar design and therefore only one ill be described in detail. Each of the modules 20 has a frusto conical shell 30 formed from plastics, such as polyethylene or similar material. Headers 32 are integrally formed at spaced intervals about the outer periphery 31 of the shell 30 and the shell 30 terminates at its upper edge at a central aperture 34. The shell has a half angle a in the order of 45" w ith the lower most portion adjacent the radially outer periphery flared to provide a shallo skirt 36. The ha l f angle ϊ of the flared skirt is in the order of 25° and smooth ly blends with the balance of the shel l 30.

100371 The shell 30 is integrally moulded with spars 40 that extend from the header 32 to the aperture 34. Each o f the spars 40 depends downwardly from the she ll 30 and has a lower edge that is formed with V shaped notches 42. F lanks 44, 46 of the notches 42 are formed with part ci rcular recesses 48 to receive tubing 50. A heat exchange core is provided by an array of tubing 50 that extends from an in let header to an outlet header. Preferably, the tubing 50. as can best be seen in figures 6 and 7, is spirally w ound from a radial ly outer location to a radially inner location and back to a radially outer location. Each run of tubing 50 is connected to a respective nipple 52 formed on the header 32 so that each run extends from an inlet header 32 to a diametrical ly opposed outlet header 32. As shown in the embod iment of Figures I 8. four headers 32 are uni form ly spaced about the periphery 3 1 of the shel l 30, allowing two runs of tubing 50. indicated by solid and dashed lines in Figure 6. to be interlaced and extend spirally inwardly and subsequently spiral ly outward ly betw een the respective headers 32.

[0038| The diameter of the recesses 48 is selected such that the tub ing 50 is a press fit w ithin the recess 48 and thereby retained on the spar 40. The press lit is such that the interior diameter of the tubing 50 is not reduced to avoid restrictions along the length of the tubing 50.

[0039| Each of the headers 32 is fonned w ith an internal shoulder 60 at its upper end and an external shoulder 62 at its lower end. T he shoulders 60, 62 facil itate the stacking of the headers 32 one above the other so that the shells 30 overl ie one another in spaced relationsh i p. The con ica l void between the adjacent shel ls accommodates the spirall wound tubi ng 50.

[0040] A pair of the headers 32 o f the lower most module 20 is connected to the inlet 1 2 by conduits 70. 72 and the diametrically opposite headers 32 interconnected to the outlet 1 4 by conduits 74. 76 (figure 1 ). The upper end of the headers 32 of upper most module 20 is sealed by a cap 78 so that flu id entering the inlet 12 passes through the header 32. along the tubing 50 to the outlet header 32 and back to the outlet 14. The cap 78 occludes the volume between the upper most nipple 52 and the upper shoulder 60. as shown in ghosted outl i ne in Figure 5. to inhibit accumulation of air within the headers 32.

[0041 ] The base 22 has a central aperture 23, aligned with the aperture 34 but o f smaller diameter, to create a central chimney through the energy transfer un it 10.

[1)0421 Liach of the modules 20 may be assembled by feeding the tubing 50 in its spiral pattern on the underside o f the shell 30. The notches 42 present an open access to the recesses 48 therehy avoiding the need to thread the pipes 50 through the spars 40. Once the tubing 50 is installed on the spars 40, it may he connected to the nipples 52 to provide a self contained module 20 that provides a heat exchange core.

[0043] The modules 20 may then be assembled by stacking one on the other until the requ isite number o f modules 20 has been assembled. The shoulders 60, 62 locate the headers 32 on one another and al low the modules to be secured by fusion welding or adhesi ve. The conduits 70 - 76 are then secured between the headers 32 and respective ones of the inlets and outlets 1 2. 14 and the base 22 secured to the lowermost module 20. The tether 24 may then be connected. The headers 32 maintain the peripheral edges 1 of the shells 30 in spaced relationship to allo fluid to pass between the shel ls and around the tubing 50 arranged on the spars 40.

J0044] In use. the pipes 1 6. 1 8 are connected to the i nlet 1 2 and outlet 14 respectivel and the assembled heat exchanger 1 submersed within a bod of water or other ground source that serves as a thermal reservoi r. Heat exchange fl uid is circulated through the pipes 16, 1 8 where i t flow s through the headers 32 and in to the tubing 50 to move between the inlet 1 6 and the outlet 1 8. As the fluid Hows, heal is transferred between the water surrou nding the tubing 50 and the heat exchange fluid in the tubing 50. The change in tem perature of the water between the shells 30, creates a density imbalance wh ich imparts a flow of fluid between the shells 30 from the radially outer edge 1 to the aperture 34 in the case where heat is rejected to the body of water. The inclined surface o f the shell 30 promotes the radial flow to the aperture 34. The Mow is enhanced by the skirt 36. which accelerates the flo radially inwardly between the shells 30 to enhance the circulation. The flow induced between the shells 30 enhances the heal Irartsfer with ihc tubing 50. The flared col lar 29 promotes the How of fluid out o the energy transfer unit 1 0, and the aperture 23 in the base 22 promotes a chimney effect from the lower base 22 to the aperture 34 to further reinforce the flow throush the shells.

[0045] It will be noted that the runs of tubing 50 provide parallel paths between the i nlet headers 32 and outlet headers 32 so that the pressure drop is maintained relatively small,

[0046] The capacity of the energy transfer unit 1 0 may readily be adjusted by add ing or subtracting the modules 20 and it wil l be noted that assem bly of the modules may be performed prior to their assembly in to the energy transfer unit 10. Of course, the energy transfer un it may consist of a single module, or may have multiple modules w here an increased capacity is required.

[0047 j A further embodiment of modular heat exchanger is shown in Figures 9 and 10. in which like components will be identified by like reference numbers with a suffix "a ^" added for clarity.

[0048] Referring to Figures 9 and 1 0, the shel ls 30a are paired to form a unit with tubes 50a spi ralling from outside to inside on one of the pairs, and from inside to outside on the other of the pairs, Kach shel l 30a has a set of radial spars 40a with para l lel sided notches 42a to receive the tubi ng 50a. The notches are si/ed to retain the tubing 50a without occluding the internal passage.

[0049 [ Four runs of tub ing 50a extends from each of a pair of diametricall opposed headers 32a and are received in alternate notches 42a along the spars 40a of the uppermost shel l 30a. The runs of tubing 50a are spaced apart vertically in each of the notches 42a and spiral inwardly to the central aperture 34a. At the radial ly inner extent of the spars 40a. the sets o f tubing 50a are d irected in to the lowermost shel l 30a of the unit where they are received in the notches 42a as they spiral radially outwardly. The tubing 50a spi rals in the same hand in the upper and lower shel ls 30a to m in imise tlow restriction in the tubes 50a. The tubing 50a of the lower shell 30a is connected to headers 32a located betw een tiie headers 32a of the upper shell to provide a circulation between inlet and outlet.

] 5 | The modules may be stacked one above the other as il lustrated above to vary- the capac ity of the energy transfer unit 1 0a with the headers 32a nesting to provide a common inlet and outlet for each of the shel ls 30a. Again, on ly a single module may be required, although typically more than one module is provided. With the arrangement of f igures 9 and 1 0, the density of tubes i n each shell is reduced, wh ich promotes circulation across the tub ing 50a from the periphery 3 l a to the central aperture 34a. whilst maintaining the modularity of the energy transfer unit. Assemblj of the tubing 50a is facil itated by avoiding cross over between the ingoing and outgoing tubes and permits an ordered assembl of the she lls 30a.

[00511 An alternate configuration of modu lar energy transfer unit is shown in Figures 1 1 and 12. Like components will be noted with like reference numerals w ith pre fix. ^" I ^" for clarity.

|0052] Referring therefore to Figure 1 I . the energy transfer unit 1 10 is formed from at least one shell 130. each of which has a frusto con ical central annular disk 1 I w ith a peripheral down turned flange 136. The disk 1 3 1 has a central aperture 134 that receives a central tube 80. The tube 80 has ports 82 distri buted about its circumference adjacent to the intersection with the intersection w ith the inner edge of shell 1 0.

[0053] The tube 80 locates a radial ly inner edge of a spar 140 that extends radial ly outwardly tow ards the flange 136. The radially inner edge of each of the spars 140 is received within a groove 84 (Figure 12) formed on the outer surface of the lube 80.

[0054] Each of the spars 140 is formed from a set o f comb l i ke strips i ndicated at 88. Each of the edges of the strip 88 has a scries of part circular recesses 148 to receive the capillary tubing 1 0. When arranged edge to edge, the strips 88 locate the capillar tubing 1 0 between opposite edges of the strips to maintain a un iform spaced relationship.

[0055J Headers 1 2 are provided at diametrical ly opposite locations on the shell 130. Each of the headers 1 32 comprises a pair of tubes 90. A row of spaced outlets ^C H is provided along each of i e tubes 90 facing in opposite directions for connection to the tubes 150. The connection between the tubes 9 and the tubing 50 is typically performed by w elding.

[0056] The arrangement of the array of tubing 1 0 within the spars 140 is sim ilar to that described above in that each is spirally wound and of opposite hand. A run of tubing I 50 therefore proceeds from one o f the tubes 90 through the pars 140 toward the central tube 80 and thereafter radial ly outwardly to terminate at the diametrical ly opposite tube 90.

[0057 | To assemble the heat energy trans fer unit 1 30, the first strip 88 of the spar 140 is secured in each of the grooves 84 on the central tube 80. The tubing 1 50 is then spi rally wound and placed into the part circular grooves and is secured in situ hy placement ofthe next ofthe strips 88. The strips are preferably are the snap fit within the grooves 84 so as to securely hold these strips 88 in alignment. The strips 88 may extend radially outwardly to the flange 136 to provide extra rigidity or may be joined to one another at the radially outer edge by a common channel or similar mechanical fastening device.

[ 05S] The next spiral array of tubing 1 0 is located in the open set of recesses 148 and the next to the strips 88 then added. This continues until all o the strips 88 have been inserted to locate the tubing 150.

10 591 In will be appreciated that the arrangement o the spars 140 made from the individual strips could be replaced with a single rectangular spar with holes formed therein and the tubing threaded through those holes. Such an arrangement would require less individual components but would increase the complexity of threading ofthe tubing.

[0060] Kaeh ofthe central tubes 80 and the tubes 90 forming the headers 132 is formed ith shoulders, as shown above with respect to Figure 5. so that the tubes 80.90 can be stacked one above the other into a unitary construction, tr!acli module 120 may therefore be formed and then multiple modules assembled to provide an energy transfer unit with the requi ite capacity.

[0061| In operation, the heat transfer fluid is circulated through the inlet header 132 where it is discharged into the tubing 150 to flo in opposite directions to the outlet header 132. The inlet 116 is provided from the lower point ofthe header 132 and the outlet 118 i¾ taken from the highest point ofthe opposite header 1 2. The transfer of heat to the surrounding water causes a radial flow o the water cither from the flange 136 to the central tube 80 through the ports 82 where heat is being rejected to the cooling water or in the opposite direction when heat is being absorbed from the water. The inclination ofthe central disk 131 promotes the radial flow between the apertures 1 4 and the flange 1 6. The inclination ofthe central disk 131 has a half angle between 65 and 75 degrees relative to the longitudinal axis ofthe tube 80 and the flange 136 is radially outwardly inclined at a half angle of 10 degrees to the longitudinal axis.

|0062] The stacking ofthe tubes 80 and the positioning ofthe ports 82 to control flo between the tube 80 and the space between adjacent shells 1 0 that accommodates the heat

- - exchange tubing 1 0 provides a pronounced ch imney effect a long the longitudinal axis of the energy transfer unit. The chimney promotes the radial flow of fluid around the tubing and therefore increases the efficiency of the unit.

[006 1 The provi sion of the shell 1 30 and the chimney e ffect from the central tube SO may also be utilized in an energy transfer unit located w ithin a housing in a manner shown in PCT Publ ication WO 2012/009S02. Such an arrangement is shown in Figures 1 3 through 1 .

[0064 ] Referring therefore to Figure 13. an energy transfer unit 21 0 has a flu id inlet 2 1 2 and an outlet 21 4. The inlet 2 1 2 and outlet 2 1 4 are connected to a heat exchange loop circulating through a heat pump in a conventional manner as referenced above.

[006 j The energy transfer unit 2 10 has a housing 21 6 made from upper and lower shel ls 21 8 to 220 respectively. The shells 2 1 8 and 220 are connected to one another at an equator 222. A number of i nlet apertures 224 are provided on the equator around the periphery of the housing 216. The upper shell 21 8 has a circular outlet 226 to receive a chimney described in greater detai l beio and the lower shel l has a number of spaced apertures 223 {F igure 15) distributed about the lower surface o the shell 220 to perm it the flow of water in to the housing 16.

[0066] The housing 216 contains a heat exchange unit 230 as best seen in Figures 14 through 16. The heat exchange unit 230 i ncludes a pair of heat exchange cores 232 to 234. each of which is formed from a pair of arrays of spiral ly wound tubing 236 that extends i n opposite hands as described above. The tubing 236 is located on p lanar vanes 240 that are umfoimally distributed about the longitudinal axis of the energy transfer unit 2 1 0. Fach of the vanes contains a matrix of holes to receive the tubing 236. As shown in Figure 1 . the runs of tubing 236 are arranged i n a staggered fashion re lative to one another although in certain circumstances, a recti l inear grid, as shown in Figure 1 9, is preferred.

[<)067| A central tube 244 extends through the housing 2 1 6 and projects though the aperture 226. T he lower end of the central tube 244 is sealed by a plate 246. The i n let 1 2 and outlet 2 14 extends along the housing 2 1 0 at diametrically opposite sides of the tube 244. The i nlet 2 1 2 and outlet 14 respectively extend radially between the co ils 232 to 234 to the radial l y outer periphery of the coils to a distribution conduit 248. The distribution conduit 248 in turn is connected through a T-piece to a manifold 250 ( Figure 1 4) which supplies each of the coils 232 to 234. Connection to the tubing 236 is provided through an elbow 252 thai carries an apertured d isk 254 (Figure 20 ). The d isk 254 has apertures 256 to receive the end of each run of tubing 236 which are received i n an aperture and welded to it to provide a secure fl uid type connection. F.ach run of tubing flares outwardly from the disk 254 and through its spiral path to an opposite mani fold connected to the outlet 2 14. The supply of heat exchange fluid through the apertured d isk 254 has been found to provide a more uniform d istribution than is obtained through a vertical manifold.

[0068] A con ical baffle 260 is interposed between the coi ls 232 and 234. The baffle 260 extends radially from the outer periphery of the coil 234 to the tube 244. Ports 262 arc provided in the tube 244 adjacent to the intersection of the baffle 260 with the tube, ^" t he ports 262 permit flow of fluid between the interior of the tube 244 and the underside of the baffle 260 with the inc l ination o f the baffle promoting radiall inward and upward flow of fluid.

[0069] A sim ilar baffle 264 is provided above the coi l 236 which terminates at a collar 268 which is concentric to the tube 244 to define an annu lus.

[0070[ In use. the heat exchanger is located between the shells 21 8 and 220 of the housing 210 w ith the collar 268 projecti ng through the aperture 226. The shel l s 2 1 8 to 220 are dimensioned to secure the heat exchangers w ithin the housing 2 16 through engagement of abutments in the housing with the spars 240. Such an arrangement is descri bed in more deta i l in the P T Publ ication noted above and need not be described in greater detail at th i s ti me.

[00711 Heat exchange fluid is provided through the in let 2 12 to the coils 232 to 234 and relumed through the outlet 214, The housing 2 1 6 is imm ersed within a body of water that provides a un i form temperature heat reservoir. If heat i s bei ng rejected to the water, i.e. as in the case w here cool ing is being affected by the associated heat pump, the temperature of the heat exchange fluids circulated through the inlet 21 2 and outlet 214 is higher than that of the surrounding water and heat is transferred to the water. The heating of the water causes a density imbalance that induces flow across the coils 234 to 232 so that fluid abuts against the underside of the baffles 260 and 264. The inclination of the baffles 260, 264 causes a flow to move rad ially inwardly and. in the case of fluid passi ng over the lower coil 234 through the

- I I - ports 262. The fluid then flows along the tube 244 and upward ly to the exterior of the housing 210.

|0072] Simi larly fluid passing over the coi l 236 is directed by the inclined baffle 264 to the annular between the collar 268 and tube 244 to emerge through the upper surface of the housing.

[0073| The fluid lost through the tube 244 and collar 26S is replen ished through ports 223 on the underside of the shell 220 and through the ports 224 provided around the equator of the housing 2 1 6. The ports 224 are positioned above the baffle 260 so that a separate flu id inlet is provided for each of the coils. In th is manner, a steady state o f heat transfer between the heat exchange flu id prov ided through the inlet 21 2 and the surrounding water is accomplished. It will be appreciated that where more than two coi ls are provided within the housing 2 16. a baffle is provided between each of the coils and set o f ports prov ided in the housing to supply each of the coils, with a corresponding set of ports 262 in the tube 244. In this manner, a modular arrangement is provided that can be adj usted to suit the particular installations. W here only a single core is required, flow may be provided from the ports 223 and the baffle is spaced from the top of the housing 2 16 to promote the radial flow.

(0074J It will be appreciated that in a heat absorbing mode, that is when heat is being supplied through the heat pump, the temperature i n the inlet 2 12 will be lower than that in the surrounding water and heat w ill be absorbed from the water. I n this case the flow is in an opposite d irection that is through the tube 244 and radially outwardly over the coils.

[0075] The inclination of the baffles 260, 264 is typical ly in the range of 5° or 30° and preferably at 20°.

[00761 As noted above, the tubing 236 i s shown in Figure 1 5 in a staggered arrangement to increase the contact of the water w ith the tubes. It has however been found that in certain conditions, such as when the water is at its maximum density around 4 degrees Celsius, thai the staggered arrangement of the tubi ng impedes the How through the coils 234 and 236. When operation in those circumstances is contemplated, the rectilinear array shown in figure 1 9 is preferred so that the tubes 236 are aligned along the axis of the lube 244 and the flow of fluid enhanced. [0077 ] The flow of water across the coi l s is induced by the density imbalance caused by the heating of water. The ch imney effect provided by the tube 244 acts to increase the n w through the lower heat exchange coi l 234. Moreover, the positioning of the collar 268 concentric to the tube 244 also increases the fluid flow across the coil 236 by inducing the How under the baffle 264 where ihe tube and collar emerge.

(0078] The provision of flow through the tube 244 and collar 268 also facil itates the installation of the heat exchange unit in a manner that avoids degradation of the heat source. As shown schematically in Figure 21. a body of water such as a lake establish at a particular depth a thermocline beneath which the waters i s al a re latively constant temperature. Above that layer, the water temperature may vary under different climatic cond itions. The placement of a conventional heat exchanger within the thermocline layer increases the temperature in that zone thereby disturbing the cooler body of water.

[0079| As shown i n Figure 2 1 , the tube 244 and collar 268 ma be extended above the housing 216. The housing 216 may then be located within the cooler body o f water w ith the outlet at an elevated temperature in the surface or upper regions of the body of water. The elevated temperature water discharged from the chimney provided by the tube 244 and collar 268 does not return to the cool water be lo the thennacl inc. which is natura! ly replenished by the source of water, such as a stream or spring that creates a lake or pond. A localised heating of lhe w ater al the surface can be observed that promotes heat loss due to evaporation and the maintenance of a steady state condition.

[0080] Th i s also perm its the energy transfer unit to be util ized i n an environment where the ground water provides the heat transfer medium to the surrounding earth. Conventional systems cause a thermal saturation of the ground water due to its lim ited How and the lower thermal conductivity of the earth, but with the chimney provided by the tube 244 and collar 268. the elevated temperature water is delivered to the surface w here evaporation promotes the dispersion o lhe heat at a reduced flow rate.