WO2011127574A1

WO2011127574A1 - Turbulator and conduit apparatus for a heat exchanger

Info

Publication number: WO2011127574A1
Application number: PCT/CA2011/000409
Authority: WO
Inventors: Rana Bose; David Velan
Original assignee: Prodigy Energy Recovery Systems Inc.
Priority date: 2010-04-13
Filing date: 2011-04-12
Publication date: 2011-10-20

Abstract

Disclosed herein is a turbulator and conduit apparatus for use in a heat exchanger. The apparatus comprises a conduit for conducting cold water along. The turbulator is located inside the conduit and has two ends held against the inner wall of the conduit. The turbulator has a helical blade member which extends between the two ends, and which defines a helical first fluid passageway along which the first fluid flows.

Description

TURBULATOR AND CONDUIT APPARATUS FOR A HEAT EXCHANGER

TECHNICAL FIELD The present concerns a turbulator and conduit apparatus, and more particularly to a screw turbulator and conduit apparatus for use in heat exchangers.

BACKGROUND

Turbulators are well known and widely used in heat exchangers to disrupt the flow of fluid, either cold water or grey water, so as to enhance thermal energy transfer from one fluid to another in a heat exchange fashion, are well-known and widely used in a number of environments to recover thermal energy from fluids. The thermal energy, if not recovered, would be lost to the environment. Generally speaking, heat exchangers work by transferring heat from one fluid to another via a solid wall, which separates the two fluids. This straightforward principle has been used to recover heat from waste water (so called "grey water") in, for example, household shower and bath systems.

Heat exchangers that employ conduits (tubes) as part of their design typically use turbulators that are located inside the conduit.

Several turbulator designs are known. One example includes strips of material with elaborate triangulated sections (see Canadian patent CA 1 ,285,269). Thus, there is a need for an improved turbulator for use in a heat exchange apparatus, in which the fluids do not contact each other and which provides efficient thermal energy transfer across single or double heat exchanger walls.

BRIEF SUMMARY We have designed a passive fluid-to-fluid heat exchange apparatus, which uses one or more single or double walled conduits in which are located a helical blade turbulator to provide unexpectedly high turbulence and mixing. The turbulator provides highly effective heat recapture from grey water commonly found in household shower and bath systems.

According to one aspect, there is provided a turbulator and conduit apparatus for a heat exchanger, comprising

- a conduit for conducting a first fluid therealong; and -a turbulator located inside the conduit and having first and second ends held against the inner wall of the conduit, the turbulator having at least one helical blade member extending between the two ends, the helical blade member defining a helical first fluid passageway along which the first fluid flows. In one example, the turbulator includes a stem extending between the two ends, the helical blade member being wound around substantially the entire length of the stem. The turbulator includes 1 , 2, 3 or 4 starts.

In one example, the conduit is double walled having an outer conduit and an inner conduit located coaxially inside the outer conduit. The inner conduit includes an outer wall, the outer conduit includes an inner wall, the outer wall being located against the inner wall to define a leak passageway therebetween. The outer conduit includes an inner knurled surface that is pressed against the outer wall of the inner conduit to define the leak passageway. The double walled conduit is helical. The double walled conduit is linear.

In another example, the conduit is single walled. The single walled conduit is helical. The single walled conduit is linear. The double walled conduit is serpentine. The single walled conduit is serpentine.

In one example, the first fluid is cold water.

In another example, the turbulator is in the form of an Archimedes screw.

According to another aspect, there is provided a heat exchanger comprising a turbulator and conduit apparatus as described above.

In one example, the heat exchanger is orientated orthogonal to the ground.

In one example, the heat exchanger is orientated horizontal to the ground.

In another example, the heat exchanger is connected to a drain trap in a shower.

BRIEF DESCRIPTION OF THE FIGURES

These and other features of that described herein will become more apparent from the following description in which reference is made to the appended drawings wherein:

Figure 1 is a schematic view of a household shower/bath system showing the location of a heat exchanger; Figure 2 is a perspective view of a vertical helical heat exchange apparatus located below a drain trap Figure 3 is a perspective view of the heat exchanger of Figure 2 showing three helical cold water conduits;

Figure 4 is a longitudinal section taken along lines 3-3 showing the double wall feature of the helical conduits;

Figure 5 is a perspective view of a portion of the double wall conduit of Figure 4;

Figure 6 is a perspective view of the helical heat exchange apparatus of Figure 2 showing the relative location of the three helical conduits;

Figure 7 is an exploded perspective view of the heat exchange apparatus of Figure 2 showing the three helical conduits;

Figure 8 is a perspective view of a heat exchange apparatus showing conduit bends;

Figure 9 is a perspective view of Koflo turbulator;

Figure 10 is a perspective view of an alternative vertical heat exchange apparatus;

Figure 11 is a perspective exploded view of the apparatus of Figure 10;

Figure 12 is a perspective view of a plurality of stacked helical double walled conduits;

Figure 13 is a schematic representation of an anti blocking feature showing a bypass conduit;

Figure 14 is a schematic representation of another anti-blocking feature showing an elongate pipe with a plurality of holes;

Figure 15 is a schematic representation of another anti-blocking feature showing a cap and mesh;

Figure 16 is a schematic representation of another anti-blocking feature showing a deflector; Figure 17 is a top view of the deflector of Figure 16;

Figure 18 is a perspective view of a horizontal heat exchanger;

Figure 18A is a cross sectional view taken along line 18-18A' showing the location of fins and two serpentine conduits;

Figure 19 is a perspective detailed view of a portion of the heat exchanger of Figure 18 showing details of the serpentine conduits and fins; Figure 20 is a perspective partial cutaway view of Figure 19 showing the location of holes and the respective serpentine conduits;

Figure 21 is a cross sectional view of part of a serpentine conduit showing the double wall feature;

Figure 22 is a perspective view of the heat exchanger of Figure 19 showing the location of the fins and conduits;

Figure 23 is a perspective view of a film heat exchanger apparatus;

Figure 24 are perspective partial cutaway views of the film heat exchange apparatus of Figure 23 showing the location of the cold water conduits;

Figure 25 is a detailed view of an end portion of the film heat exchange apparatus of Figure 23 showing the location of the cold water conduits and the drain plate;

Figure 26 is a perspective view of a shell of a horizontal heat exchange apparatus;

Figure 27 is a perspective view of serpentine conduits located inside the apparatus of Figure 26;

Figure 28 is a top view of an alternative film heat exchange apparatus showing the location of the cold water conduits;

Figure 29 is a cross sectional view of the cold water conduits of Figure 27;

Figure 30 is an exploded view of a manifold showing the location of the double wall conduit in the manifold;

Figure 31 is a detailed view of the manifold of Figure 30 showing the conduit located in the manifold;

Figure 32 is a schematic representation of a gravity thermosyphon for use with any heat exchange apparatus described herein;

Figure 33 is a front view of an alternative heat exchange apparatus disposed in a vertical orientation;

Figure 34 is a schematic representation of the heat exchange apparatus of Figure 33 showing the location of the cold water conduits adjacent a drain plate;

Figure 35 is a perspective view of a heat exchange apparatus located in a trench drain;

Figures 36A-36C are diagrammatic representation of a number of surface turbulation patterns; ures 37A-37G are diagrammatic representations of a number of turbulator inserts;

Figures 38A-38D are diagrammatic representations of a number of grey water inserts;

Figure 39 is a perspective view of an Archimedes screw turbulator;

Figure 40 is a side view of a portion of the Archimedes screw turbulator; Figure 41A-41 D are side views and end views of a number of Archimedes screw turbulators showing different starts;

Figure 41 is a side view of a heat exchange apparatus showing the location of the Archimedes screw turbulator in a cold water conduit; and

Figures 42A-42E are diagrammatic representations of cross sectional views of turbulator designs.

DETAILED DESCRIPTION

Definitions

Unless otherwise specified, the following definitions apply: The singular forms "a", "an" and "the" include corresponding plural references unless the context clearly dictates otherwise.

As used herein, the term "comprising" is intended to mean that the list of elements following the word "comprising" are required or mandatory but that other elements are optional and may or may not be present. As used herein, the term "consisting of is intended to mean including and limited to whatever follows the phrase "consisting of. Thus, the phrase "consisting of indicates that the listed elements are required or mandatory and that no other elements may be present.

As used herein the term "fluid" is intended to mean gas or liquid. Examples of liquids suitable for use with the heat exchangers described herein include, but are not limited to, water, hydraulic fluid, petroleum, glycol, oil and the like, and steam. One example of a gas includes combustion engine exhaust gases.

As used herein, the term "turbulator" when referring to either a surface or to an insert having a surface that acts as a turbulator, is intended to mean that the surface has a plurality of projections extending away from the surface. Surface turbulators and inserted turbulators are used to increase convection rates and heat transfer coefficients at heat exchange surfaces in fluid passageways in order to provide high performance in compact heat exchange assemblies, and to orientate fluids into a pre-defined direction often resulting in chaotic paths. Examples of types of turbulators include, but are not limited to, corrugations, peaks and troughs, nubbins, raised chevrons having a gap between, fish scales, raised zigzag moldings, meshes, criss-cross oriented wires, porous materials, and the like. Turbulators may comprise uniform or non-uniform surface profiles, textures, open cell structures, and shapes. Fluid passageway geometry allows control of fluid flow via solid or semi-solid mechanical structures and may be constructed from laminate composites, molded parts, and meshes of plastics, ceramics, metals or other materials. Specific examples of turbulators described herein, include an Archimedes screw type turbulator, which is used in cold water passageways only.

We have discovered that a combined helical turbulator and conduit apparatus can be used in a heat exchanger to produce surprisingly high turbulence and mixing of cold water (a first fluid), and unexpectedly high thermal energy transfer from grey water (a second fluid) to cold water.

The combined turbulator and conduit apparatus, which is described in more detail below, comprises a conduit that conducts the first fluid therealong. The turbulator is located inside the conduit and has two end ends, which are held against the inner wall of the conduit. The turbulator has at least one helical blade member extending between the two ends. The helical blade member defines a helical first fluid passageway along which the first fluid flows. The turbulator is one example is in the form of an Archimedes screw. The turbulator and conduit apparatus can be used with any of the heat exchange apparatuses, which will now be described below.

Referring now to Figure 1 , a heat exchange apparatus is shown generally at 10 in use with a household shower and bath system 12. The household shower and bath system 12 includes a water heater 14, a hot water line 16, a cold water line 18, a warm water line 20, a mixing valve 22, a shower head 24 and a drain trap 26. The hot and warm water lines 16, 20 are each connected to the mixing valve 22, the temperature of the water exiting the shower head 24 being controlled by the user operating the mixing valve 22. The cold water line 18 is connected to the heat exchange apparatus 10 and feeds cold water 25 (a first fluid) into the apparatus 10. The warm water line 20 is connected to the heat exchange apparatus 10 and the mixing valve 22. The drain trap 26 receives drain water 28 (so called "grey water") (a second fluid) from the shower/bath tub and communicates the drain water to the heat exchange apparatus 10. After flowing through the heat exchange apparatus 10, the grey water 28 exits the household shower system 12 to a main drain (not shown). It should be noted that although an example of a household shower/bath system is illustrated, the heat exchange apparatus described may also be used for other applications that require heat exchange between two fluids. Furthermore, it is to be noted that any of the heat exchangers described hereinbelow can also be connected to the system 12.

I. Helical double walled heat exchange apparatus

Referring now to Figures 2, 3, 4 and 5, a helical double wall heat exchange apparatus is shown generally at 10. The apparatus 10 is for use in household applications and can be connected to the drain trap 26 in a typical household shower, bath or sink. The apparatus 10 may also be used for industrial or commercial applications in which high volumes of waste grey water are used. Advantageously, the apparatus provides thermal energy recapture of about 80% in a heat exchanger with a vertical height of 20^" and a nominal inner diameter 3^" with pressure loss below 5psi at 10 litres per minute flow. By contrast, a Delstar mesh vertical heat exchanger has effectiveness in the range of 70% for a heat exchanger of 72^" with comparable pressure loss. The apparatus 10 is typically used in the vertical orientation, i.e. is orthogonally disposed to the ground. The apparatus 10 comprises at least one helical double wall conduit 30 and a drain conduit 32. The helical double wall conduit 30 is a first fluid passageway 34 for the first fluid 25, typically cold water, at a first temperature, typically about 10°C. The helical double wall conduit 30 includes an outer conduit 36 and an inner conduit 38 located coaxially inside the outer conduit 36, which define the first fluid passageway 34. The drain conduit 32 includes a second fluid passageway 40 for the second fluid 28, typically grey water, at a second temperature, typically about 40°C. The drain conduit 32 includes an upper drain portion, which is connected to the drain trap 26 such that grey water flows from the shower into the drain conduit 32. The helical double walled conduit 30 is located in the drain conduit 32 and downstream of the second fluid 28 flowing therethrough. The second fluid 28 when it flows in the second fluid passageway 40 effects thermal energy (heat) transfer to the first fluid 25 flowing in the first fluid passageway 34 across the inner conduit 38 and the outer conduit 36. The inner conduit 38 includes an outer wall 42, the outer conduit 36 includes an inner wall 44, the outer wall 42 being located against the inner wall 44 to define a leak passageway 46 therebetween, which can vent to the atmosphere if either of the inner or outer walls 42, 44 ruptures or is pierced. In one example, the outer conduit 36 includes an inner knurled surface that is pressed against the outer wall 42 of the inner conduit 38 to define the leak passageway 46. In another example, the inner wall 44 of the outer conduit 36 is smooth and is pressed against the outer wall 36 of the inner conduit 38 to define the leak passageway 46.

Cross-connection of plumbing devices is ruled by strict, but variable, local regulations, where grey water and fresh cold water are present within the same heat exchange apparatus. Thus, a double wall design is desirable over any other protection means to prevent fresh water contamination by grey water in the event of system failure, such as if the heat exchanger wall is ruptured or pierced. As best illustrated in Figures 3, 6 and 7, the heat exchange apparatus 10 includes three helical double wall conduits 30A, 30B and 30C. A first outer helical double wall conduit 30A, a central helical double wall conduit 30B and an inner helical double wall conduit 30C. The circumference of the helices of the double wall conduits 30A, 30B and 30C decreases from the outer conduit 30A to the inner conduit 30C. The helical conduits 30A, 30B and 30C are located in the drain conduit 32 such that they are stacked adjacent each other, yet are sufficiently spaced apart to define the second fluid passageway through which the grey water can flow. Each of the helical conduits 30A, 30B and 30C are coaxially orientated and include turns in the same direction. In the examples illustrated, the helical turns in conduits 30A, 30B and 30C are counterclockwise. However, one skilled in the art will recognize that the helical coils can also turn in a clockwise direction. Thus, waste grey water flowing along the second fluid passageway contacts the outer surfaces of the helical coils 30A, 30B and 30C, which act as thermal energy exchange surfaces, as it moves along the second fluid passageway and is able to efficiently transfer its thermal energy across the double wall of the helical conduits to the first fluid flowing in the first fluid passageway. It is also possible that instead of the helices 30A. 30B, and 30C being stacked, they may also be located offset from each other. Optionally, a low voltage heating wire, heating coil or heating tape (not shown) may be located inside the conduits 30A, 30B, and 30C. This provides not only turbulation of the cold water, but also provides additional heat so that the heat exchanger 10 can provide all the heat required for the application (i.e. no longer passive and does not need to be combined with an external heating system).

Referring now to Figure 8, the heat exchange apparatus 0 may have additional features such as a plurality of bends 31 located at the upper end of the apparatus 10. Each bend 31 is connected to a double walled conduit. The bends 31 are made before and then the conduit is coiled to create two helices, one on top of the other. It is not the same as a double helix, which has two helices made from one conduit, but the helices are on two separate diameters. Advantageously, the location of the bends 31 allows the cold water connectors 33, 35 to be located either at the top of the apparatus 10 or the bottom, which is useful in applications where the apparatus 10 is to be located in a space-restricted area.

In one example, the first and second fluids flow in a contra-flow manner through the heat exchange apparatus 10. It is also possible to have the fluids flow in a parallel flow manner. A first temperature T1 of the first fluid 25 entering the first fluid passageway 34 is typically less than the second temperature T2 of the first fluid 25 as it exits the first fluid passageway 34. Similarly, the third temperature T3 of the second fluid 28 entering the second fluid passageway 40 is greater than the fourth temperature T4 of the second fluid 28 as it exits the second fluid passageway 40. By way of example, T1 is typically 10°C for cold water, T3 is typically 40°C for grey water and T4 is typically 30°C for grey water exiting the heat exchanger 10, and T2 is typically 24°C for warmed water entering the warm water line 22 from the heat exchanger 10. To measure the effectiveness of the heat exchange apparatus, the following equation is used:

Effectiveness = Tcold out - Tcold in

Tgrey in - Tcold in

where T denotes temperature in °C

At least one of the fluids flows through its respective passageway under pressure, the other fluid flowing through its respective passageway at atmospheric pressure. Typically, the second fluid (the cold water) flows under pressure at approximately 50 psi along the first fluid passageway 34.

Figures 13, 14, 15, 16 and 17, illustrate a number of features, which may be added to the vertical helical double wall heat exchange apparatus to prevent blocking of the heat exchanger. Although the features are used primarily for sinks, they may also be used in other applications. Figure 13 illustrates a bypass conduit 40, which includes a mesh 42 that blocks large particles from entering the heat exchanger 10. The mesh 42 forces the particulates into the bypass conduit 40. An optional deflector or blocker 44 may be located in the central core of the drain conduit. Figure 14 illustrates a length of vertical orientated conduit 46 located at the top of the core of the drain conduit 32 and includes a plurality of holes 48. Grey water passes through the holes 48 to the exchanger 10. Particulate or larger debris is prevented from entering the exchanger and so passes down the centre of the drain conduit. Figure 15 illustrates a cap 50, which blocks a center bypass channel 52. When the cap 50 is closed, grey water is forced to the sides where it falls onto vertically disposed helical double walled conduits. Optionally, the sides can have a mesh 51. The cap 50 can be operated manually or automatically. The cap 50 can be a twist cap, a magnetic plug, or powered by motor or hydraulic action. Referring to Figure 16 illustrates a deflector 54, which forces all particulate matter to the sides of the heat exchanger 10. The deflector 54 is located such that there is always adequate clearance so that any material that moves through the top will fit around exchanger, after being forced to the sides. Figure 17 illustrates a top view of the deflector 54. The deflector 54 is a cone with side plates 56. The cone forces water onto side plates 56, which drop then, falls onto the exchanger. A gap 58 between each side plate 56 is sufficiently large such that any material that fits through exchanger opening will fit through gap 58.

Referring to Figures 10, 11 and 12, an alternative embodiment of a vertical heat exchange apparatus is shown generally at 60. The apparatus 60 comprises an outer shell 62, a grey water inlet 64, a grey water outlet 66, a cold water inlet 68 and a cold water outlet 70. An inner shell 72 houses a plurality of stacked helical double wall conduits 74 (in the example illustrated four conduits are provided). The conduits 74 each receive cold water from the common cold water inlet 68 and the warmed water exits the heat exchanger via the common outlet 70. The multiple stacked helices provide for heat exchange with reduced pressure loss compared to a single helix of the same height.

II. Serpentine double walled heat exchanger

Referring now to Figures 18, 18A, 19, 20, 21 and 22, an alternative heat exchange apparatus 100 is illustrated. The heat exchange apparatus 100 comprises an elongate housing 102 having a housing inlet 104 and a housing outlet 106. The housing inlet 104 is connected to the drain trap 26 (not shown) or may be located anywhere downstream of the drain and defines the first fluid passageway for the first fluid, typically grey water. Typically, the heat exchange apparatus 100 is orientated horizontal relative to the ground so that the apparatus 100 can be located under, for example, the shower base. The elongate housing 102 includes two sidewalls 108 having a plurality of openings 110 therein. The openings 110 are arranged in groups of two along the sidewalls 108 and include an upper set 112 and a lower set 114. The lower set 114 are staggered away from the upper set 112, although it is possible that the upper and lower sets 112 and 114 can be located collinear with each other. At least one serpentine double wall conduit 116 is connected to the elongate housing 102 and passes through the upper set 112 of openings 110. A first plurality of conduit elbows 118 extend away from the sidewalls 108 along substantially the entire length of the elongate housing 102. A second serpentine double wall conduit 120 is connected to the elongate housing 102 and passes through the lower set 1 4 of openings 110. A second plurality of conduit elbows 122 extend away from the sidewalls 108 along substantially the entire length of the elongate housing 102. Additional serpentine double wall conduits can be used depending upon the application that is contemplated by the user. In the examples illustrated, a substantial portion of the serpentine conduits 116, 120 is located inside the elongate housing 102 and is thus able to contact the grey water, which flows through the housing 102. It is also possible that all of the serpentine conduits 116, 120 are located inside the elongate housing, thereby eliminating the conduit elbows exterior of the housing. This example is useful in applications where a more streamlined heat exchange apparatus is needed in, for example, space restricted locations.

Referring now to Figure 18A, a plurality of fins 124, which may be corrugated along their surface, are mounted around the outer wall of the serpentine conduits 116, 120. The fins 124 are disposed parallel to each other and extend substantially the entire length of the elongate housing 102. The serpentine conduits 116, 120 and the fins 124 are located in the lower portion of the housing 102 such that they define a gap 126 thereabove of sufficient size to allow the use of cleaning tools or inspection of the apparatus during routine maintenance. A cap 128 is mounted over the elongate housing 102, which can be easily removed to expose the serpentine conduits 116, 120 and the fins 124. For ease of illustration, the openings 110 described are shown in the outer fin 124 and correspond to the openings in the adjacent sidewall 108. For ease of description, only one serpentine conduit will be described in detail with reference to Figures 18A and 21. The same description applies to the serpentine conduit 120 The serpentine conduit 116 is doubled walled and includes an outer conduit 132 and an inner conduit 134 located coaxially inside the outer conduit 132, and which defines the first fluid passageway for the first fluid, typically cold water. Optionally, a low voltage heating wire, heating coil or heating tape (not shown) may be located inside the conduit 116. The heating wire may serve to increase turbulence (see below) of the cold water flowing in the conduit and/or increase the cold water temperature so that the heat exchanger 100 can provide all the heat required for the application (i.e. no longer passive and does not need to be combined with an external heating system). As described above in the heat exchange apparatus 10, a ventable leak passageway 136 is located between the inner and outer conduits. The grey water when it flows along the second fluid passageway contacts the serpentine conduits 116, 120 and the fins124 so as to effect heat transfer to the cold water fluid flowing in the serpentine conduits 116, 120 across their respective outer and inner conduit walls. III: Film heat exchanger

Referring now to Figures 23, 24 and 25, an alternative heat exchange apparatus is shown generally at 200. The heat exchange apparatus 200 is for applications that typically require the heat exchange apparatus to be located horizontal to the ground. The heat exchange apparatus 200 comprises an elongate housing 201 having an outer shell 202, a drain plate inlet 204, a drain plate outlet 206 and a drain plate 208. The drain plate inlet 204 can be connected to the drain trap 26, as described above. A plurality of double walled straight (linear) conduits 210 extend in parallel along the drain plate 208. A plurality of conduit inlets 212 are located at one end of the drain plate 208 and a plurality of conduit outlets 214 are located at another end of the drain plate 208 The conduits 210 are double walled as described above for the heat exchange apparatus 10 and 100, and will not be described here. The conduits 210 define the first fluid passageway for the cold water. The drain plate 208 has a drain plate surface 216 through which at least a portion of the double wall conduits 210 extend. The drain plate surface 216 is of sufficiently large area to define the second fluid passageway for the second fluid such that the second fluid flows as a fluid film along the second fluid passageway and effects heat transfer to the first fluid flowing in the first fluid passageway across the inner and outer conduits of the conduits 210.

The drain plate 208 may be angled to provide a slope along the sides of the plate at the front end and a raised portion at the back end so as to force the grey water towards the conduits located at the extreme edges of the drain plate, and yet maintains the ability of the heat exchanger to self drain. An alternative embodiment of the heat exchange apparatus 200 is shown in Figures 26, 27, 28 and 29 in which a plurality of serpentine conduits 21 OA, 21 OB, 21 OC and 21 OD are fully located inside the elongate housing 201 and are located close to each other, yet with a space between each conduit to allow waste grey water to flow thereover. The conduit inlets 212 and the conduit outlets 214 are located at either end of the serpentine conduits. The area of the drain plate is sufficiently large to create a thin film of grey water as described above. The elongate housing 201 is located inside a shell 203, which includes a gradual entry, and gradual exit which reduces clogging risk. The heat exchange apparatus 200 can be made using plates that are die formed such that they create the same flow path as if in conduits. The double wall plates with serpentine flow paths can then be formed and welded to create a vertical cylinder as another construction for the vertical helical heat exchanger 10. Additionally, the same plates can also be made using a thermally conductive injection moulded plastic. The horizontal film heat exchanger 200 can be located underneath a shower floor having a false drain, which lead to the true drain. Alternatively, the drain plate is located on the floor of the shower and is able to directly capture heat from grey water as it flows thereover. Additionally, the heat exchanger 200 may be incorporated directly into either a dishwasher or a washing machine or any other appliance, which uses hot water.

Built-in options may be included within any of the heat exchange apparatuses described herein in order to increase overall system performance and durability. These options include thin wall elements; laminar flow disruptor elements; check valve systems; one or more external level indicators; anti scaling capabilities such as, for example, mechanical devices and passage configurations to reduce scaling, anti-scaling coatings, vibration, chemical, and electrical means; anti corrosion means such as, for example, electrical, chemical, anodic, cathodic, and coatings; and water hammer protection such as, for example, shock absorbers, flexible or relatively soft and elastic cold water circuit components. Additional features may include use of an insulating shell on the systems and subsystems. System leaks and malfunctions can be detected in a variety of ways using, for example, relative flow measurement and/or pressure transducers and gauges located at strategic points in the heat exchange apparatus. The heat exchangers may be self draining in both horizontal and vertical positions. If electric power is required for monitoring or control equipment, power sources such as batteries, thermoelectric, or micro-turbines can be advantageously used in combination or alone.

It is known that greater thermal transfer performance and ease of manufacturing are obtained by using a thin formed sheet material in the manufacturing process of the heat exchanger components. Using thin wall stainless steel composite sheets of approximately 0.015" to 0.035" thicknesses in heat exchanger apparatuses provides low resistance to burst due to possible excessive high internal cold water pressure, such as those commonly used in household or industrial plumbing systems. The aforesaid heat exchangers can be used in many applications such as for example in household shower/baths, in washing machines and the like. In the design for use in household shower, grey water typically drains at 10 litres/hour. For commercial applications, however, manifolds may be Advantageously, the serpentine conduits described for heat exchanger 100 and 200 (Figures 26 through 29) increase the dwell time of cold water in contact with the grey water. This is in contrast with elongate conduits and the bends outside the grey water. Thus, cold water conduit bends are located inside the grey water passageway so that the dwell time is increased and cold water never leaves the heat transfer area while inside the exchanger. IV. Manifolds

Referring now to Figures 30 and 31 , a manifold 300 is illustrated which provides double wall leak off and can be used to mount and secure the double wall conduits of any of the heat exchange apparatuses described herein to the respective apparatuses. The manifold 300 comprises an outer conduit connector 302, an inner conduit connector 304 and a flow director 306. The connectors 302, 304 include openings 308 for receiving the double wall conduits 210 (for example) therein. The outer conduit connector 302 and the inner conduit connector 304 include knurled surfaces 308, which provide a double wall leak passageway 310 through which cold water can flow in the event that the integrity of the double wall conduit is compromised. The manifold 300 may be a double manifold located at either end of heat exchange apparatus and may be for single or multiple circuits of conduits. Additionally, cold water can flow into and out of the same manifold or in an independent manifold.

V. Gravity Thermosyphon

Referring now to Figure 32, a gravity thermosyphon 400 is contemplated fro use with the heat exchange apparatuses as described herein. The thermosyphon 400 comprises a bath 402 of refrigerant material such as ethylene glycol in which the second fluid passageway carrying the grey water is located. Located above the second fluid passageway are the double walled conduits, such as for example, the conduits 210. A deflector 403 may be located between the conduits 210 and the grey water passageway. The grey water flowing along the second fluid passageway causes the refrigerant to heat up and evaporate (see wavy lines). The evaporated refrigerant 405 contacts the double wall conduits carrying the cold water, which flows into the conduits 210 at a first end 404. The vaporized refrigerant 405 condenses on contact with the cold conduits 210 and returns to the bath 402. The thermal energy from the vaporized refrigerant thermally transfers to the cold water so that it exits the conduit 210 at a second end 406 at a higher temperature. The process repeats so long as the grey water and the cold water flow in their respective passageways. VI: Alternative film heat exchange apparatus

Referring now to Figures 33 and 34, an alternative embodiment of a heat exchange apparatus is shown generally at 500. The heat exchange apparatus 500 comprise one or more single or double walled conduits 502, as described herein, which define a first fluid passageway 504 for a first fluid at a first temperature. A drain plate 506 having a drain plate inlet 508 and a drain plate outlet 510 and a drain plate surface 512 is located either generally orthogonal to the ground, generally horizontal to the ground or angled relative to the ground to create an incline. A portion of the single or double walled conduits 502 is located in intimate contact with the drain plate 506, which has a surface of sufficient area to define a second fluid passageway 514 along which the grey water flows by gravity. The location of the conduits 502 against the drain plate 506 provides a passageway of the grey water which flows as a film 516 over the conduits 502 to efficiently effect heat transfer to the first fluid flowing in the first fluid passageway across the single or double walled conduits 502. The drain plate inlet 508, as best illustrated in Figure 34, is connected to an outer shell 520, which is located over the conduits 502. The drain inlet 508 is shaped to force the grey water along a deviated path 518 towards the conduits 502 to create the film 516 thereagainst thereby effecting heat transfer across the wall or walls of the conduits 502. Thus, heat exchange occurs on only one side of the apparatus. Furthermore, the width of the drain plate 506 is larger than the width of the feed pipe (not shown) so as to create the film 516, which flows along the second fluid passageway. As above, turbulators can be used inside the cold water passageway to increase heat exchange.

The surfaces of the heat exchange apparatus 500 can be coated with a non-stick coating such as TEFLON to prevent fouling by debris

As best illustrated in Figure 35, any one of the heat exchange apparatus described herein can be located in a trench drain 520. Common manifolds 522 and 524 are connected to their respective cold water inlets and warmed water outlets. In the example illustrated, grey water enters the trench drain 520 and passes downwardly over the conduits and effects heat exchange. For most applications, the width of the trench drain is about 12-inches, whereas the height is about 8- inches.

VII. Turbulators Referring now to Figures 2, 3, 24 and 27, the drain conduit 32, the linear conduits 210, the helical conduits 30A, 30B and 30C, and the serpentine conduits 1 16, 120 can be used with or without turbulators of the type known in the art. In particular, as seen in Figure 36A, all or a portion of the inner wall of the conduits may have grooves, which enhance cold water turbulence. Also, as seen in Figures 36B and 36C, corrugated or spiral conduits may also enhance the thermal energy transfer surfaces of the drain conduit. Turbulator inserts, as seen in Figure 37A through 37G, known to those skilled in the art may also be used to enhance thermal energy transfer. Figures 37A through 37C illustrate examples of the turbulator inserts that include a twisted plastic or sheet materials with variable pitch. The greater the pitch, the more turbulence, more pressure loss and therefore higher heat transfer. Surface patterns such as herringbone or straight patterns may also be added to the inserts, as seen in Figures 37B and 37C. Twisted wire turbulators or rope as seen in Figure 37D, whereas a mixing nozzle insert for use at a nozzle entry located in the cold water conduit are also useful, as seen in Figure 37E and 37F. Figure 37G is another type of turbulator design, which is manufactured by Statomix™ Additional turbulator designs are also useful for location in the grey water passageway is illustrated in Figure 38A through 38C. In one example, Figure 38A, fins are located exterior of the cold water conduit and project into the grey water passageway to cause turbulation of the grey water. Figure 38B is an insert, which can be located inside the grey water passageway and may include holes through which the cold water serpentine or helical conduits can pass. The insert includes a surface pattern, which causes turbulation of the grey water. Figure 38C is a torpedo-shaped insert, which may be located in the grey water passageway to effect turbulation of the grey water. Figure 38D is a helical double wall torpedo insert, which when located in the grey water passageway causes turbulation of the grey water. The configuration of the torpedo-shaped inserts simulates grey water movement in a direction orthogonal to the ground. The flow of fluids can be passive, i.e. by gravity or can flow under the influence of pressure, either above or below atmospheric pressure. The heat exchange apparatus described herein are also self-draining. Moreover, due to their design, the helical can be located directly in a grey water pathway with or without the use of pre-filtration to remove particulate debris. Additional clog reduction features may include hair deflectors, non-stick coatings on the thermal transfer surfaces, or, in the case of the fins 126, the fins may have polished knife edges.

In one example, grey water flows over the three helical conduits, by gravity, such that it exchanges its heat (typically about 40°C) to the source of cold water flowing through the conduits located in intimate contact with the drain conduit. In certain examples, higher fluid temperatures (>100°C) may be used to also exchange thermal energy to cold water so as to generate steam. The heat exchange takes place across a thin (typically from about 1/1000 inch to about 1/5 inch thickness) double wall arrangement. The cold water flowing in the first cold water passageway is heated to produce warmed water, which may then be stored in a storage tank or communicated to a mixing valve in a shower or bath system. Advantageously, the heat exchange apparatus is constructed from inexpensive materials and when installed is essentially maintenance-free. The grey water conduits (pipes) used are standard 1.5 to 4 inch and are universally retrofittable into existing plumbing systems with the minimum of disruption to the household. At least one of the thermal transfer surfaces is uneven. In one example, one thermal transfer surface is corrugated and defines a plurality of fin-like peaks (or blades) and troughs that extend longitudinally along the channel member 30 between the first and second end portions.

As illustrated in Figure 9, a turbulator that is manufactured by Koflo is available in short lengths for purpose of mixing fluids. It is possible to manufacture a longer version of this for creating turbulence in cold water in our heat exchangers. The turbulator includes a plurality of half circles connected in an X pattern at each centre of the half circle. This design forces water to mix in two directions i.e. left handed and right handed competing threads.

Figure 39 illustrates a new design of a combined turbulator and conduit apparatus 600, which can be used in any one of the heat exchanger designs described herein. The combined turbulator and conduit apparatus 600 includes a conduit 602, which may be single or double walled, along which the first fluid (cold water) flows. A turbulator 604, which includes first and second ends 606, 608, is located inside the conduit 602, the ends 606, 608 being held against the inner wall of the conduit 602 at the respective ends of the conduit 602. The turbulator 604 includes at least one helical blade member 610 connected between its two end 606, 608 and defines a helical first fluid passageway along which the first fluid flows. In one example, the turbulator 604 is an Archimedes screw like design in which the blade 610 is wound around a stem 612 along substantially its entire length.

A plurality of Archimedes' screw turbulators can be used in the conduits depending upon the design of the heat exchange apparatus and the length of the conduits. It is possible to have a plurality of Archimedes screw turbulators located end-to-end. It is also possible to include Archimedes screw turbulators having blades of varying pitch angle, size and number. The Archimedes screw blade design will depend on numerous factors known to those skilled in the art including, for example, the viscosity of the fluid flowing along the blades, the temperature of the fluid, whether the fluid is under pressure and/or moving under gravity and such. Furthermore, the Archimedes screw turbulator can be used with the linear conduits 210, the helical conduits 30A, 30B and 30C, and the serpentine conduits 1 16, 120, as described above.

Referring now to Figure 40, the Archimedes screw turbulator includes a plurality of roots 616, a plurality of crests 618 and a plurality of flanks 620, which are located along substantially the entire length of the Archimedes screw turbulator. A minor diameter 61 1 is measured between two opposing roots 616; a major diameter 615 is measured between two opposing crests 618. A pitch diameter 613 is measured along two lines each of which bisects two opposing flanks 620. In our Archimedes screw, there is typically a large difference between the minor diameter 61 1 and the major diameter 615. This large difference permits more cold water to flow through the turbulator at any given time. The Archimedes screw turbulator also includes a pitch distance 622, which is measurable between two adjacent crests 618; a flank angle 624 which is a measure of the angle of the flank 620; and an angle 626 which is measurable between two opposing angled flanks 620. The Archimedes screw turbulator is typically measured in terms of threads per inch, which indicates the number of complete turns of the path per inch, which in our case is one. Referring now to Figures 41A-41 D, there is illustrated a number of Archimedes screw turbulator designs which show progressively increasing numbers of starts from 1 , in Figure 41 A through to 4 in Figures 41 D. As the number of starts increases, the threads per inch decrease. Thus by varying the numbers of starts along the length of the Archimedes screw turbulator, it is possible to create a number of distinct fluid pathways. We have observed that by increasing the number of starts, the pressure drop in the turbulator can be lowered without significantly lowering the heat transfer across the conduit 602.

As best illustrated in Figure 42, the combined turbulator and conduit apparatus 600 can be located inside a shell 62 of the type described above. Typically, the combined turbulator and conduit apparatus 600 is located at the base of the shell 62 over which the grey water flows thereby effecting heat exchange to the turbulated cold water flowing along the cold water passageway in the conduits.

As best illustrated in Figures 43A through 43E, additional turbulator designs are shown in cross section. The outer edge of the helical blade member has a surface pattern, which can be square toothed (Figure 43A); pointed teeth (similar to a fly wheel) (Figure 43B); and spoked having a V- groove located at regular intervals along the blade's edge (Figure 43C). Another turbulator design includes, as illustrated in Figure 43D, a fly wheel design having grooves along the surface to accommodate additional flexible turbulators 614. As illustrated in Figure 43E, a standard spot welded twisted tape designed turbulator may be included in which the twisted tape includes four starts. All of the above turbulators may include multiple starts or be spirally threaded with coatings thereon to prevent accumulation of debris.

The intent of the various contours or surface patterns of the turbulators is to enable interactive variation between turbulence, flow and thereby heat transfer.

The contours of the turbulator do not contact the inner diameter of the conduits. A space is typically located between the outer edge of the blade and the inner sidewall of the conduit to allow the cold water to over flow and pass through without being intercepted by any solid walls. The turbulators are simply inserted into the conduits 602.

The conduits are bent and dip slightly where they meet the manifold, as described above. The bends and dips of the manifold prevent the turbulators from moving around inside the conduits, yet they are not permanently attached to conduits. 1

Other Embodiments

From the foregoing description, it will be apparent to one of ordinary skill in the art that variations and modifications may be made to the embodiments described herein to adapt it to various usages and conditions.

Claims

We claim:

1 A turbulator and conduit apparatus for a heat exchanger, comprising

- a conduit for conducting a first fluid therealong; and

-a turbulator located inside the conduit and having first and second ends held against the inner wall of the conduit, the turbulator having at least one helical blade member extending between the two ends, the helical blade member defining a helical first fluid passageway along which the first fluid flows.

2. The apparatus, according to claim 1 , in which the turbulator includes a stem extending between the two ends, the helical blade member being wound around substantially the entire length of the stem.

3. The apparatus, according to claim 1 , in which the turbulator includes 1 , 2, 3 or 4 starts

4. The apparatus, according to claim 1 , in which the conduit is double walled having an outer conduit and an inner conduit located coaxially inside the outer conduit.

5. The apparatus, according to claim 4, in which the inner conduit includes an outer wall, the outer conduit includes an inner wall, the outer wall being located against the inner wall to define a leak passageway therebetween.

6. The apparatus, according to claim 5, in which the outer conduit includes an inner knurled surface that is pressed against the outer wall of the inner conduit to define the leak passageway.

7. The apparatus, according to claim 4, in which the double walled conduit is helical.

8. The apparatus, according to claim 4, in which the double walled conduit is linear.

9. The apparatus, according to claim 1 , in which the conduit is single walled.

10. The apparatus, according to claim 9, in which the single walled conduit is helical.

11. The apparatus, according to claim 9, in which the single walled conduit is linear.

12. The apparatus, according to claim 4, in which the double walled conduit is serpentine.

13. The apparatus, according to claim 9, in which the single walled conduit is serpentine.

14. The apparatus, according to claim 1 , in which the first fluid is cold water.

15. The apparatus, according to claim 1 , in which the turbulator is in the form of an Archimedes screw.

16. A heat exchanger comprising a turbulator and conduit apparatus according to any one of claims 1 to 15 above.

17. The heat exchanger, according to claim 16, is orientated orthogonal to the ground.

18. The heat exchanger, according to claim 16, is orientated horizontal to the ground.

19. The heat exchanger, according to claim 16, is connected to a drain trap in a shower.