CONDUIT ASSEMBLIES FOR HEAT EXCHANGERS AND THE LIKE

Abstract

A heat exchanger for a sanitary shower or the like includes a primary flow conduit, and secondary flow conduit sections, each conduit section having a substantially flat wall spaced from and aligned with an adjacent surface of the primary conduit so as to avoid accumulation of dirt. The secondary conduits may have internal walls and a mesh may be provided for spacing conduit surfaces.

Description

BACKGROUND OF THE INVENTION

This invention relates to conduit assemblies for heat exchangers and the like. It also relates to heat exchangers and sanitary apparatus such as shower systems containing heat exchangers in drainage paths thereof.

This invention is particularly but not exclusively applicable in devices or components for heat exchange between fluids in general and in particular for heat exchange between two liquids flowing under disparate heads of pressure within constrained spaces, particularly for the recovery of heat from waste water draining from a sanitary shower, such as is described in WO2009/101161 (Gilbert), which is entirely incorporated herein by reference.

That document discloses a primary flow conduit containing secondary conduit sections. The first fluid conduit has formations in its surface adjacent the secondary conduit sections and corresponding thereto in shape. This may provide recesses for trapped air or make air pockets which interfere with optimal fluid flow distribution or which necessitate an elaborate means of venting. Dirt (or silt) may accumulate over time in gullies, deposited out of suspension and that may interfere with optimal fluid flow. Cleaning or rinsing manually may be difficult. The apparatus may be technically demanding or complicated to fabricate with the necessary precision, positional stability and be susceptible to disturbances in the uniformity of spacing between the heat-exchanging and enclosing primary conduit surfaces.

The present invention aims to alleviate at least to a certain extent the problems of the prior art.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided a thermally conductive conduit assembly being mountable in a primary (fluid) flow conduit of a heat exchanger or the like, the conduit assembly including two or more series of elongate conduit sections comprising a first and second series having the conduit sections thereof arranged next to one another such that each series extends in a series direction which is generally transverse to the conduit sections, each conduit section in at least the first series having at least a portion along the length thereof which has a cross section having on a wide side of the conduit portion a substantially flat first wall which is substantially aligned with the series direction, the cross section also including a protruding wall formation in the conduit portion extending (protruding) towards a corner (angle or vertex) on a narrow side of the conduit portion located opposite the wide side (being it's counterpart) and being internested (interposed) between conduit sections of another internesting series, with the substantially straight (flat) wall substantially coincident with a general (net) flow direction of said primary flow conduit. The narrow side of the said portions of conduit sections comprise an elongated convex surface (ridge), so the term “corner” used in defining the first aspect refers to this ridge and the corresponding angle that the protruding wall formation makes in cross section perspective.

The conduit assembly described hereinabove may thus be considered to be a secondary flow conduit for the transfer of heat between a secondary fluid flowing therein and a primary fluid which the primary flow conduit of the heat exchanger (or like) conducts to flow therein. Preferably, the secondary fluid flows through a sequence (succession) of conduit sections of the conduit assembly along one or more flowpaths so as to provide a counterflow heat exchange arrangement. Thus a further aspect of the invention provides a heat exchanger assembly which comprises a conduit assembly as set out in the first aspect which is mounted inside a primary flow conduit which has a general flow direction therethrough which is coincident with the substantially flat wall, the conduit assembly and the primary flow conduit being arranged for heat transfer between respective fluids therein.

According to a further aspect of the invention there is provided a heat exchanger assembly having a primary flow conduit having a general flow direction therethrough, and a conduit assembly mounted in the primary flow conduit, the conduit assembly including first and second series of elongate conduit sections, each series having the conduit sections thereof arranged next to one another in rows extending in a direction generally transverse to the conduit sections and coincident with the general flow direction through the primary conduit, each conduit section in at least the first series having at least a portion along the length thereof which has a substantially flat wall which is substantially in line with a substantially flat wall of one or more adjacent conduit sections in the same series (row), in the general (net) flow direction through (i.e. of) the primary flow conduit.

The primary conduit has an internal wall surface spaced from and substantially aligned with the substantially flat wall. Said internal wall surface may be substantially flat and parallel to said substantially flat walls of a plurality of said conduit sections in a said series which is adjacent to the internal wall surface.

A second side of a conduit section joins one (elongated) edge of the wide side to one (elongated) edge of the narrow side, whilst a third side of a conduit section joins the other (elongated) edge of the wide side to the other (elongated) edge of the narrow side.

According to a further aspect of the invention a conduit assembly is provided wherein the conduit sections of the first and second series have a second and a third side with external walls thereof shaped and arranged in such a way that second side walls of the first series complement the third side walls of the second series, and second side walls of the second series complement the third side walls of the first series so as to generally provide a substantially consistent gap for the passageway there between of a layer of fluid having generally a thickness which is not substantially varying thereat.

A number of features will now be described which may be optionally included in embodiments in accordance with any one or more of the above aspects of the invention:

Each conduit may have a protruding wall portion which extends towards the other of the first and second series. That is, the first and second series have general orientations opposing (facing) one another, the orientation of each being in common with the orientations of the protruding formation with respect to the wide side (first wall) of each of their respective conduit sections (e.g. up vs. down, left vs. right, inward vs. outward). Conduit sections of the first series are preferably internested with conduit sections of the second series.

The protruding wall portion may be internested between conduit sections of the second series or another series of elongated conduits.

That is, the narrow sides of the first series' conduit sections are closer than the wide sides to the wide sides of the second series' conduit sections, and vice versa (for those of the second series).

The conduit sections may be straight, or substantially straight. Alternatively, the conduit sections may be curved, in which case they may be arranged in a spiral. In either case, the wide sides of the conduit sections of each series may be substantially in line, so as to follow (or be tangential with) a line, which may be straight or gently curved, as viewed on a cross section of the said conduit sections.

The protruding wall portion may comprise two generally flat wall portions such that said cross section is substantially triangular. The protruding wall portion may be substantially symmetrical about a line substantially perpendicular to the substantially flat first wall.

The conduit sections in the other series may each have a cross section the same as the cross section of the first series. The conduit sections of the first series may be internested between sections of the second series wherein each conduit section of the second series may have at least a portion along the length thereof which has a cross section having on a wide side of the conduit portion a substantially straight (flat) first wall which is substantially aligned with the series direction, the cross section also including a protruding wall formation in the conduit portion extending (or protruding) towards a corner (including an angle or vertex) on a narrow side of the conduit portion located opposite the wide side (being a counterpart thereof) and being internested between conduit sections of the first series, with the substantially straight (or flat) wall substantially coincident with a general (or net) flow direction of said primary flow conduit and/or substantially in line with a substantially flat wall of one or more adjacent conduit sections in the second series (or row).

Said conduit sections may have internal walls extending therealong. The internal walls may extend fully across an inside of said sections to divide the interior of said sections into a plurality of conduit paths within each said conduit section. The internal walls may provide thermal bridging from positions within said conduit sections to exterior walls thereof and may provide enhanced structural stability to the said conduit sections.

A further aspect of the invention provides a conduit assembly for a heat exchanger which comprises an elongate conduit section which has an internal wall extending therealong and arranged to act as a heat flow bridge from fluid in the conduit section to an external wall of the conduit section.

Each conduit may be extruded and of constant cross section therealong.

A conduit assembly may have one or more components preferably made of plastic or resin which interconnect thermally conductive conduit sections at their ends.

A further aspect of the invention provides a conduit assembly mounted in a primary conduit having an adjacent internal wall portion that is spaced from and substantially aligned with the substantially flat wall of a thermally conductive conduit section.

Preferably the primary conduit has one or more portions of internal wall, which are substantially flat and parallel to the substantially flat wall of a plurality of thermally conductive conduit sections in the first and/or second series of the conduit assembly, which are adjacent to the said internal wall. A further aspect of the invention provides a conduit assembly for a heat exchanger which includes at least two adjacent conduit surfaces arranged for fluid flow therepast in a fluid flow direction, and at least one flexible elongate spacing member arranged to be located between the conduit surfaces to establish or stabilise a defined space therebetween.

The flexible elongate spacing member may be part of a mesh, the mesh including a plurality of said flexible elongate spacing members, which are interconnected by joining members.

At least one said flexible elongate member may be generally aligned with a said fluid flow direction.

Said joining members may be elongate lengths of material, in which case they may be thinner than said at least one flexible elongate spacing member.

Said flexible elongate members in some preferred embodiments may be cords, strings or straps.

Said joining members in some preferred embodiments may be cords, strings or straps.

A further aspect of the invention provides a heat exchanger assembly in which the primary flow conduit and conduit sections are mutually arranged for counterflow heat exchange generally between flows passing through the respective primary conduit and thermally conductive conduit sections.

In embodiments of the invention the substantially flat walls of the conduit sections of the conduit assembly and/or the primary flow conduit are generally horizontally arranged.

In other embodiments thermally conductive conduit sections can be made principally from copper, aluminium or an alloy comprising substantially one of these metals, such as brass.

A further aspect of the invention provides a sanitary assembly such as a shower facility, which includes an assembly in accordance with any previous aspect of the invention. A further aspect of the invention provides a heat transfer conduit formation comprising pairs of generally linear series of sections of said conduit. The sections have like formation and orientation to one another, and each section in a said series is aligned with or consistently offset from the next in the same series and having an outer surface including or consisting of three sides. The surface(s) of one side are substantially flat and in a substantially co-planar or co-linear arrangement with surface(s) of at least one other section in the same series, the two series being in a substantially parallel, near co-planar or co-linear and inversely orientated arrangement with their respective conduit sections internested with one another and spaced apart by a generally constant offset distance.

The sides may be joined by corners or sections, which may be sharp, rounded or beveled. The sides other than the substantially flat side may be flat, may have varying curvatures or may be of varied curvature.

Sides of the conduit sections other than the substantially flat side may be substantially symmetrical about a line normal to the substantially flat side.

Surfaces of a second side of each section may correspond inversely in shape to surfaces of a third side of said conduit sections.

The conduit sections may have a cross section, which is triangular. Alternatively, the cross section may be at least partly: trapezoidal, shaped like the profile of a wide-rimmed bell or hat, sinusoidal, shaped like the profile of a shark fin, or having one outwardly convex side adjacent an outwardly concave side.

The conduit sections may have internal walls extending longitudinally which extend thereacross internally.

The conduit sections may be formed from various materials, including one or more of copper, copper alloy such as bronze or brass, stainless steel, aluminium, aluminium alloy, or another metallic or other type of alloy.

The conduit sections may be arranged as a succession of convoluting loops or loops that may form a flat, conical or cylindrical spiral of any shape, the axis of rotation of which may be orientated vertically (or otherwise, such as horizontally), whereby each loop may form a pair with an adjacent loop of conduit section in an adjacent series. The loops may be arranged extending generally horizontally.

The conduit formation may be arranged for heat exchange with a primary conduit of a heat exchanger for heat exchange between a first fluid in the primary conduit flowing substantially as layers over the outer surfaces of said conduit formation. The flow in the primary conduit may be transverse or oblique to the direction of a second fluid flowing along and within the said conduit formation. The heat exchanger may be arranged for heat to flow from the first fluid to the second fluid. The heat exchanger may be arranged with the conduit formation located inside the primary conduit. Overall, the heat exchanger may be a counter-flow heat exchanger.

The shape of adjacent sections of said conduit formation and/or spacing between them may vary incrementally along a said series, thereby gradually varying the thickness of the flowing first fluid layers in the primary conduit so as to regulate overall the resistance to first fluid flow.

The said conduit sections may be joined to one another by sections of joining conduit made of plastic, resin, rubber or similar material. The sections of joining conduit may be mutually interconnected and/or amalgamated so as to form composite blocks. The joining conduit sections may be arranged to generally reverse the direction of flow along the said sections of thermally conductive conduit formation. The conduit section may be horizontally arranged and situated within or below a drainage basin so as to be submersed in the flow of waste water as a said first fluid in a said primary conduit that drains from a sanitary shower facility and to conduct fresh water as a said second fluid to which heat from the waste water may be transferred.

A further aspect of the invention provides a heat exchanger device containing a conduit formation as set out in the previous aspect of the invention. The heat exchanger device may have strips or patches of thermally conductive surface at least partly lining a fluid conduit which surrounds and has a face which faces the first sides of said conduit sections of at least one said series. The conduit sections may be thermally bridged with the thermally conductive surface via ridges, ribs or spines, which support or mount the conduit sections in the heat exchanger.

A further aspect of the invention includes a formation of a thermally conductive fluid conduit into sections having three or at least three sides extending longitudinally in an arrangement suitable for incorporation within a heat exchange device for heat transfer between a first fluid flowing as layers in a primary conduit over the outer surfaces of the said conduit sections and a second fluid flowing within the said conduit sections in an overall counterflow direction transversally to the first fluid flow, characterised in that: the sections are arranged into pairs of layered series whereby the surfaces of one side of the conduit sections of each layer are substantially flat so as to be alignable with a common imaginary geometric surface which is consistently spaced from one side of a surrounding first fluid conduit surface of a heat exchange device.

The sections of each series, which may be loops or semi-loops, may be arranged spaced from and in the same geometric orientation as one another and may be arranged generally or substantially in a line or row.

Paired layers of conduit sections may be mutually superimposed and overlapping whereby the sections of one layer or series may be internested (or interlaced or interposed between) conduit sections of the other layer in the pair.

The formation may include several paired said layers located adjacent one another and may, for example, have four layers or series in two pairs or six layers or series in three pairs.

Each paired layer of conduit sections may have an inverted orientation with respect to its counterpart layer. The surfaces of a second side of one layer's sections may face a surface of a third side of the other layer's sections or vice versa.

Mutually facing surfaces of respective second and third sides of interlacing adjacent sections may be consistently spaced from or offset from one another, having like formation and like alignment. The conduit sections may extend longitudinally in a direction that is substantially parallel to a common geometric surface of a heat exchanger or the like with which one side of the conduit sections is alignable or aligned.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be carried out in various ways and a number of preferred embodiments of conduit assemblies and heat exchangers in accordance with the invention will now be described by way of example and with reference to the accompanying drawings, in which:

FIG. 1 is a schematic cross section through an example of a shower tray incorporating a preferred conduit assembly and heat exchanger in accordance with the invention;

FIG. 2 is a schematic cross section through a modified version of the embodiment of FIG. 1;

FIG. 3 shows examples of three further embodiments of conduit assembly and heat exchanger in accordance with the invention;

FIGS. 4A to 4C show modified versions of the three examples shown in FIG. 3;

FIG. 4D shows an example of an end cap for use in the conduit assemblies of FIG. 3 and FIGS. 4A to 4C;

FIG. 4E shows an example of an end cap segment, as illustrated in FIG. 4D, viewed from the perspective of the conduit section ends;

FIG. 4F shows an example of a spacing mesh, which may be used with the various embodiments described herein;

FIG. 5 shows a cross section through an extruded triangular conduit section to be used in series of conduit sections arranged in rows as in FIG. 3 or FIG. 4A;

FIG. 6 is a general view of a shower assembly including the conduit assembly of FIG. 1; and

FIG. 7 shows a schematic view from above of an embodiment similar to those shown in FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 6 shows a general view of a shower tray assembly 100 having a shower head 102, side outlets 104, boiler 106 and shower tray 110 incorporating the heat exchanger assembly 108 which is shown in more detail in FIG. 1. As shown in FIG. 6 water from a fresh water inlet 112 may be directed to the shower head 102 and outlets 104 via a pipe circuit 114 via either heating coil 116 in the boiler 106, heat exchanger assembly 108, or both. Recirculation through the heat exchanger 108 may be bypassed by opening a valve 118, flow through the boiler by a boiler flow shutoff valve 120, main shutoff/flow control valve 122 may control total output flow. Divert control valve 124 may control proportions of flow to the shower head 102, and side outlets 104 and thermostatic control valve 126 may control outlet flow temperature.

Water from the shower head 102 and side outlets 104 falls on to shower floor top 130, which is circular, then falls down into peripheral channel 132 before passing under a peripheral lip 134 contiguous with the shower floor 130 before passing radially inwardly through a primary flow conduit 136 bounded by upper and lower generally flat surfaces 138, 140 before passing over central circular weir 143 and exiting to drainage (not shown) via outlet 144.

While flowing through the primary flow conduit 136, the fluid therein is subject to a cooling heat exchange in which it heats fresh water passing through two series (i.e. upper series (or layer) 172 and lower series (or layer) 174) of spiral conduit sections 142.

The spiral conduit sections 142 are arranged as shown in FIG. 7, where not all parts are shown for the purposes of clarity. The arrangement, as in FIG. 1, does have therefore relatively central inlets 150 to the secondary flow conduit sections 142, which are connected by a pipe 152 to inlet port 154, as well as a relatively peripheral outlet 156 connected by pipe 158 to outlet port 160 as shown in FIG. 7, although not all of these parts are shown in FIG. 1.

Essentially, the flow through the spiral sections 142 in FIG. 1 starts at an innermost pipe section 164 in the lower series that is shown and continually loops around and around, in incrementally increasing diameter, through adjacent spiral loop 168 and so on until final outer loop 170. In this way, heat exchange between the fluid (waste water) in the primary conduit 136 and the fluid (fresh water) in the secondary conduit spiral sections 142 is generally counterflow. Flow in the primary conduit is also generally always at any given local position generally perpendicular to the local section of secondary conduit 142. The secondary flow is split to flow in parallel along an upper series 172 and a lower series 174 of conduit sections 142 as envisaged here, with part of the flow passing in a single spiral through all of the upper pipes of the upper series 172 and part of the flow passing in another single spiral through all of the lower pipers of the lower series 174.

As shown in FIG. 1, the conduit sections 142 each have an outer cross section, which is substantially that of an equilateral triangle. Each triangular section has a flat outer wall surface 178, which is spaced from and substantially parallel to an adjacent one of the flat upper and lower surfaces 138, 140 of the primary flow conduit 136. This arrangement makes it hard for air or contaminants, such as grit or sediment, to accumulate in the primary conduit being horizontally oriented. Each conduit also has a protruding outer surface portion consisting of second 180 and third 182 external surfaces (or sides) of the triangular cross section. The second and third surfaces meet at a corner 184. The conduit sections 142 in each of the upper and lower series can, therefore, be said to be formed in lines or rows, which are generally linear in the radial direction. Also, each corner 184 of each section extends through an imaginary line between the two corners 184 of the immediately adjacent conduit section in the other series 172, 174. Therefore, the conduit series are internested or interlaced with one another.

The walls 138, 140 may be slightly curved in which case the substantially flat wall 178 may be very slightly curved, either slightly convex or concave to follow the curve of the adjacent one of the walls 138, 140 but these walls are nevertheless substantially flat in general.

As shown only in part and in dotted lines in FIG. 1, radially extending upper 190 and lower 192 spacing ribs may be provided, an imaginary outline 194 being present in the drawing to show where the dotted lines end in the outwardly radial direction. In reality the ribs 192, 194 extend radially fully across the shower floor 130 and they serve both to support the shower floor 130 and space and locate the secondary conduits 142 inside the primary conduits.

The shower floor 130 may be removable for cleaning purposes, as can the conduit sections 142 and ribs 190,192, if desired.

FIG. 2 shows a modification of the arrangement in FIG. 1 in that the second and third sides 180,182 of the conduit section forming the protruding portion are replaced by a generally part-sinusoidal or bell or hat-shaped protuberance 183.

FIG. 3 shows three other types of conduit cross-sections and how they may be arranged, aligned and offset with respect to adjacent conduit sections, for the transverse flow of a first fluid in layers above, below and in between the conduit sections. In this embodiment, the conduit sections 142 are all straight and may be extruded or otherwise formed. Respective ends 200 of the straight pipes 142 may be inserted into end caps or blocks 202 as shown in FIG. 4D and 4E in order to reverse flow direction. End caps 202 may be arranged such that flow passes in serpentine (zigzag) fashion separately along each of the upper and lower series (this may make cleaning easy since the series may easily be removed separately) or may circulate (loop) up and down between the two series at each end cap.

The left hand example in FIG. 3 shows that the corner 184 of the cross section of the conduit sections 142 may be blunted such that the section is trapezoidal. The middle example in FIG. 3 shows how in another modification the second face may be outwardly concave and the third face outwardly convex. The right hand example in FIG. 3 shows a modification in which a similar shape is used as in FIG. 2 and wherein an internal surface 208 of each conduit section is circular so as to resist deformation under pressure.

FIGS. 4A, 4B and 4C show developments of the respective left-hand, middle and right-hand examples in FIG. 3, wherein internal walls 220 are provided extending along all of the way inside the conduit sections 142. With the conduit sections formed of material with good heat transfer properties such as copper or an alloy thereof, the internal walls promote heat transfer between the interior of the secondary conduit sections and the outer surfaces 178, 180, 182 thereof. Internal walls 220 also serve to strengthen the secondary conduit sections against deformation under pressure.

As shown in FIGS. 5, with triangular secondary conduit sections 142 the interior walls 220 may split the secondary conduits into multiple internal channels 230 extending all of the way therealong, for example six (FIG. 5) or nine channels. The first wall 178 as shown here is supported and spaced from the adjacent primary conduit wall 140 by ridges or ribs 192 on the primary conduit wall aligned with the direction of primary fluid flow. The sections shown can conveniently be produced by extrusion, e.g. of metal or metallic alloys such as copper, aluminium or their alloys. Each interior channel 230 may, as shown in FIG. 5, communicate directly through a single outer wall section 232 to the outer wall surface of the conduit section 142, thereby giving each channel 230 good heat transfer access to the exterior thereof. Each conduit section may include a centre point 234 defined by a join of a plurality of generally straight wall portions 236.

In the embodiments of FIGS. 3 to 5, which have straight conduit sections 142, the shower tray associated therewith may be generally rectangular with a central or edge drain channel (not shown), with overall configuration bearing some resemblance therefore to that shown in FIGS. 10 to 12 of WO2009/1011671 (Gilbert). The number of rows of conduits in each series of conduit sections may be chosen to suit each particular application. Some embodiments may, for example include between about 15 and 30 conduit sections in each series.

Although the series may be paired as shown in FIGS. 1 to 4C, a second or third pair of conduit series may be used in other embodiments, each pair running generally parallel to the others. Ones of said substantially flat surfaces 178 of the conduit sections 142 may in these cases be arranged spaced from and substantially parallel to one another with a similar spacing therebetween to that between the conduit sections 142 and the upper 138 and lower 140 wall surfaces of the primary conduit 136.

In the various embodiments herein, similar components have been given similar reference numerals. In FIGS. 3 and 4A to 4C, although the upper and lower surfaces 138, 140 of the primary conduit 136 have been shown in line with the substantially flat surfaces 178 of the conduit sections 142, in practice there are slight gaps between the surfaces 138, 140 and flat surfaces 178 of the conduit sections 142 as shown in FIGS. 1 and 2.

As shown in FIG. 4F, a mesh or net 400 may be provided having mutually parallel thick cords 402 and mutually parallel thin cords 404, which run across to the thick cords 402. The thick cords 402 may be about 0.6 to 1.0 mm or 1.5 thick. The thin cords are thinner. The mesh 400 may be placed between the upper series of conduit sections and the lower series (and between the upper series and the upper surface 138, and between the lower series and the lower surface 140) and may flex into position as the two series are drawn towards one another during assembly. The mesh may be positioned with the thin cords 404 normal to the general flow direction through the primary conduit and thick cords generally parallel thereto. The thick cords serve as spacers for the secondary conduits and for supporting the shower floor 130 so that weight thereon does not disadvantageously reduce the gaps between the various components and affect flow adversely. The thin cords, however, allow flow to pass thereby and serve to promote turbulent flow and therefore good heat transfer. It will be understood that the mesh may have different configurations dependent upon the configuration used for the conduit sections, such that the thick cords may remain locally aligned with the general flow direction and the thin cords normal thereto. For example, with spiral-shaped conduit sections 142 as in FIGS. 1 and 2 hereof, the thick cords 402 may be generally radially arranged and the thin cords 404 may be generally arranged in spirals or circles.

Further discussion of the embodiments now follows. In each of the described embodiments, a thermally conductive conduit formation or assembly is arranged as a succession or series of sections or loops within a device for counterflow heat transfer between a fluid flowing within conduit sections of the conduit assemblies and a fluid flowing as layers of generally consistent thickness in a primary flow conduit, this flow being transversally across or obliquely crossing over or passing in between said conduit sections. The direction of flow of the first fluid layers in the primary conduit may (at any given point) be substantially or fully perpendicular to the direction of second fluid flow in the conduit sections (as seen from a point of view normal to a common geometric surface, such as a generally flat or slightly curved inner surface of the primary conduit) or the generally planar orientation of the overall heat exchanger device, or at a given or variable angle obliquely crossing over the secondary fluid conduit sections. Overall, through the heat exchanger, the respective flows in the primary conduit and second conduit sections in preferred embodiments interact in a counter-current manner for counterflow heat exchange therebetween.

The layered flow of the first fluid (which may be generally laminar or turbulent) in the primary conduit is intermittently divided into separate layers as it passes passing by each secondary fluid conduit section on each of both sides (above and below) that reconnect in temporary confluence between successive conduit sections.

Outer layers of the fluid flow in the primary conduit is in a relatively straight and direct path in the gap between flat sided surfaces of the secondary conduits and enveloping sides of the primary conduit.

An inner layer of first fluid in the primary conduit flows in a relatively longer undulating flow path between mutually facing second and third sides of the secondary fluid conduit sections.

Heat exchange device implementations with more than one pair of layers of secondary fluid conduits are envisaged and will also have one or more inner layers flowing directly straight between mutually spaced and facing flat sides of the secondary fluid conduit sections.

A locally regulated distance between the facing sides of the second fluid conduit sections and the enveloping primary fluid conduit surface is established so as to provide a substantially uniform distribution of heat transfer through all exposed surfaces of the thermally conductive second fluid conduit. This may take into consideration all relevant technical factors, including: the frictional resistance to first fluid flow in the primary conduit induced by the conduit surfaces of the conduit sections; the viscosity of the first fluid in the primary conduit, and variations resulting from temperature changes; the cross sectional area of the first fluid flow front in the primary conduit; and/or resistance to first fluid flow in the primary conduit induced by local bends in the layered flow's flow path therein.

In some embodiments, the outer or straight-flowing layer gaps or spacings next to the interior surfaces of the primary conduit may be smaller than the inner or undulating layer gaps or spacings. Optimal distances may in some preferred embodiments be determined through experimentation or the testing of computational models with fluid dynamics simulation software, such as CFD or EFD programs.

The term “consistent” in reference to conduit gaps, offsets or spatial arrangements may in some preferred embodiments refer to constancy or uniformity that is consistently related to the constancy or variation of the technical factors with which it may be related, and these may not necessarily be always constant.

For example, the spacing between facing conduit sides (or the first fluid flowing layer thickness in the primary conduit) may increase in correspondence to: a narrowing in width of the layers (or first fluid cross sectional flow front); a decrease in temperature of the first fluid; an abrupt change in local flow direction or a turbulent juncture; and/or a decrease in the exposure to heat exchange surface area. These factors may combine in such a way as to negate or promote each other to some degree, so the consideration of each and any of these relationships should not be taken so absolutely as to not consider it in relation to the influence of other factors.

The juncture between second and third longitudinal sides/faces of each conduit section opposite a first longitudinal side/face thereof may be selected from a variety of shapes, such as rounded, filleted, beveled or indented. In some embodiments, a fourth side or longitudinal face may be positioned and uniformly offset from the enclosing surface of the layered fluid conduit and in some embodiments the conduit section may thereby have a trapezoidal cross section. This juncture or fourth side may be substantially narrower than the first side and spaced further apart from the enclosing fluid conduit surface of the primary conduit than the corresponding first side to allow for the combined passage of fluid layers coming from (or going to) both the equivalent second or third sides and the first side of an adjacent conduit section, which thereat converge and/or diverge and may blend.

Preferred embodiments have particular application within a flat device for the recovery of heat from wastewater draining from sanitary showers having substantially flat surfaces of the primary conduit surrounding the secondary conduit sections. The substantially flat primary conduit surfaces may be horizontal or slightly inclined, substantially planar or slightly curved, and may be arranged together with the secondary conduit sections for near co-planar (i.e. having alignment within: a common plane; a nearby parallel plane; a nearby nearly parallel plane; or a generally/nearly parallel nearby nearly planar surface, e.g. slightly domed, humped or conical) countercurrent flow of the two fluids within the same general planar zone, which may comprise in some embodiments a region bounded by two nearby parallel planes or a region in the vicinity of all of a number of near co-planar surfaces.

The conduit formations or assemblies described in the embodiments hereof may be employed with general applicability in broader contexts beyond the scope detailed above wherein each conduit section sequence is aligned with non-planar surfaces which are offset one from another, such as in helical formations aligned with concentric cylindrical, prismatic or frustrumatic surfaces.

Thus, notwithstanding the attributes appropriate for a conventional shower basin context, the invention may also be applied in embodiments having heat-exchanging conduit sections arranged in non-planar forms such as a dome, cone, pyramid, frustum or indeed any other (preferably symmetrical) primary conduit surface formation.

It is not always necessary for the secondary conduit sections to conform entirely to the characteristics and attributes outlined herein. For example, if a significant part of the second fluid conduit (and/or the primary fluid conduit) in a heat exchange device has the determining characteristics of this invention, its effectiveness will not be undermined, only that it may be limited proportionally to that part. Therefore, the terms “sections of conduit” and “surfaces of a side of conduit sections” or words to such an effect of meaning may be taken to refer only to those sections or surfaces of the conduit having the characteristics and attributes described.

Further, in some embodiments, the cross sectional shape of the secondary conduit sections may incrementally change in the relative dimension of its sides or parts or in its shape, even morphing from one type of shape to another along the length thereof.

The paired layers or series of secondary conduit sections may be parallel with regularly spaced conduit sections along the series (i.e. along the general direction of flow in the primary conduit) in some embodiments, such as those shown in FIG. 1, FIG. 3, FIGS. 4A to 4C, and 5, or may have incrementally converging conduit sections along the series in other embodiments (such as that shown in FIG. 2), by virtue of the nature of the cross-sectional shape or according to factors described above.

The pressure of the fluid flowing within the secondary conduit sections may generally be substantially greater than that of the first fluid, and may in certain formations tend to promote temporary distortion of the cross-sectional shape, which may change irreversibly if excessive. These shape distortions, if allowed to develop, could have a detrimental effect upon the appropriate functioning of the device and are normally best avoided. Thus, some embodiments may employ a natural variation of the intended shape that becomes more appropriate when distorted under pressure. This for example may take the form of concave sides instead of flat sides, which may become more like flat surfaces in operation.

The description of shapes defined in the claims therefore do not necessarily refer to the natural or unstressed shape of the conduit but may refer to a shape that the conduit may adopt under the stress of operational fluid pressures. To support high secondary fluid pressures well, embodiments of this invention may have a variable conduit wall thickness or have one or more circular interior tubes carrying the fluid inside the external surface shape (such as the right-hand example shown in FIG. 3). Such a section, including interior tubes, may be extruded into the desired shape or made from conventional tube parts with welded or attached corner ridges forming the outer walls of the secondary conduits that may be made of the same material or a thermally conductive composition different to that of the tube(s).

Taking advantage of modern industrial techniques, the thermal transfer conduit may alternatively be an extruded polymer with thermally conductive additives or insets (e.g. metallic fibers) to thermally bridge the inner and outer surfaces of the conduits. The addition of metallic granules as an additive to the polymer, which aggregate predominantly at the extruded conduits' surfaces, also promotes the appropriate distribution of heat more evenly over the conduits' surfaces to where it may more effectively transfer to/from the fluid.

As already described, the heat transferring conduits of this invention do not require any necessary correspondence of shape between the inner and outer sides, as seen in the cross-section. Thus, the interior of each secondary conduit may in some embodiments of this invention be advantageously fragmented (as shown in FIGS. 4A to 4C and 5), so as to increase the surface area available for heat transfer with the fluid flowing within (without extending the devices overall dimensions) and render the outer surface more resistant to shape distortion under high differences of fluid pressure across it. In this instance, the heat transfer conduit's passageway and the fluid flowing within it will also be correspondingly fragmented, as illustrated in FIGS. 4A to 4C, and 5, due to the presence of internal walls longitudinally aligned along and within the conduit sections which extend across and separate the overall cross sectional area into separate enclosed portions. Heat transferring conduits having such cross sectional shapes with fragmented passageways, such as those shown in FIG. 5 can be made by an extrusion process from copper, aluminium or an alloy such as brass or aluminium alloy which effectively distributes the internally absorbed heat to the outer surface of each conduit section by virtue of its excellent thermal conductivity.

Conduit surfaces may advantageously be coated or plated with a material different to the extrusion material (e.g. copper on aluminium). The extruded conduit section may be subsequently curved to form appropriately shaped sections as particular embodiments of the heat exchange device require, such as the spirals like those of the embodiments of FIGS. 1 and 2.

Whilst the conduit sections may be identically shaped with identical cross-sections, in other embodiments the shape of the sections may change gradually or incrementally along the series without substantially affecting the regular offsetting or spacing of the secondary conduit sections from the primary fluid conduit surfaces for uniformly layered flow therethrough.

To enhance the heat transfer available to the surrounding fluid the outer surfaces of the conduit sections and/or the primary flow conduit may be treated, scored, grooved and/or undulated. Scores, grooves or undulations (not shown) may be formed extending transversely to, obliquely to or in alignment with the local direction of fluid flow through the primary conduit. An alternative, with high performance in avoiding the accumulation of grime, fouling or bio-slime, is to line conduit-supporting ribs or battens (of and in the enclosing primary flow fluid conduit) with a thermally conductive surface, which extends along the surrounding (counter-facing) surface that is offset from the first side of each secondary conduit section. The thermally conductive surfaces around each rib supporting a single section of secondary flow conduit may in some embodiments be inter-connected with adjacent rib sections along (i.e. in the direction of) the section of second flow conduit but should preferably not be thermally interconnected with adjacent rib sections supporting the adjacent parallel sections of second flow conduit, so as to avoid substantial dissipation of the thermal gradient that incrementally progresses along the series of secondary flow conduit sections.

Additional embodiments of conduit assemblies in accordance with the invention may comprise or be used as part of low height heat recovery devices for the transfer of heat from warm wastewater flowing in a drainage system under gravity to fresh water. Thus, such embodiments in accordance with the invention may be used as or as part of heat exchange devices for installation within or under the drainage basin of sanitary showers.

In some additional embodiments, the conduit surfaces may be coated with a surface treatment or layer of material (eg copper over aluminium), to resist fouling, microbial growth and/or corrosion.

Outer surfaces of the conduit sections may feature indentations or grooves where wall is thickest (eg. at corners or between passageways formed by internal walls inside the conduit sections), the indentations or grooves advantageously increasing the surface area available for heat exchange and/or enhancing turbulent flow so as to provide better heat transmission). Additionally, the indentations or grooves may provide a feature with which a protrusion on the surrounding primary conduit surface can couple or attach for structural stability.

Outer surfaces of the conduit sections may have indentation features, cuts or holes (e.g., screw holes formed in flanges formed thereon) at one or more positions along their length. These may be arranged to fit or complement a protrusion/protruding feature on or attached to a surrounding primary conduit surface to provide good structural stability.

Outer surfaces of the conduit sections (which may be triangular or substantially triangular in cross section) and/or the counter-facing surfaces of a surrounding primary conduit surface may have ridges, protrusions or shallow formations to enhance fluid mixing or turbulent flow (for better heat transfer), e.g. chevrons. The chevrons may be aligned with flow through the primary conduit, such as by having a sharp end thereof pointing in an upstream direction.

While the flow in the primary conduit is often described as in layers, the layers in some embodiments may be fragmented or merely substantially layer-like, for example if one or more of the surfaces of the conduit sections and the primary conduit surrounding the flow is fluted and/or if there are spacers (e.g. to space and locate the conduit sections within the primary conduit) or walls/flow-fences or turbulence-forming features within the flow space in the primary conduit which fragment the layer.

In some embodiments strings, lines (for example of polymer) or a series of webs, straps or mesh may be employed within the primary flow conduit and/or between the conduit sections. These may be sandwiched between the conduit surfaces to transmit weight loads and maintain the optimal spacing and/or promote fluid turbulence. The spacing may typically be 0.6-1 mm, although different minimum spacing between surfaces within the primary conduit (including between the conduit sections) may be applied in some other preferred embodiments. In some further embodiments, a mesh for this purpose may have first lines substantially aligned with the flow and acting as spacers cross linked with second lines which may be generally transverse to the flow to create turbulence and, in this case, the second lines may be thinner than the first lines so that they allow flow past themselves.

It is envisaged that various changes may be made to the embodiments described without departing from the scope of the invention as defined in the accompanying claims.

Claims

1. A thermally conductive conduit assembly mountable in a primary flow conduit of a heat exchanger, the conduit assembly comprising:

a first series and a second series of elongate conduit sections, the first and second series Being arranged next to one another such that each series extends in a series direction generally transverse to the conduit sections, each conduit section in the first series having at least a portion along the length thereof which has a cross section having on a wide side of the conduit portion a substantially flat first wall which is substantially aligned with the series direction, the cross section also including a protruding wall formation in the conduit portion extending towards a corner on a narrow side of the conduit portion located opposite the wide side and being interested between conduit sections of the second series, with the substantially flat wall substantially coincident with a general flow direction of said primary flow conduit.

2. A heat exchanger assembly, comprising the conduit assembly as claimed in claim 1 mounted inside a primary flow conduit having a general flow direction therethrough, which is coincident with the substantially flat wall, the conduit assembly and the primary flow conduit being arranged for heat transfer between respective fluids therein.

3. A heat exchanger assembly, comprising:

primary flow conduit having a general flow direction therethrough; and

a conduit assembly mounted in the primary flow conduit, the conduit assembly including a first series and a second series of elongate conduit sections, the first and second conduit series being arranged next to one another in rows extending in a direction generally transverse to the conduit sections and coincident with the general flow direction through the primary conduit, each conduit section in at least the first series having at least a portion along the length thereof which has a substantially flat wall which is substantially in line with a substantially flat wall of one or more adjacent conduit sections in the same series in the general flow direction through the primary flow conduit.

4. The assembly as claimed in claim 3, wherein the conduit sections in the second series each have at least a portion along the length thereof which has a cross section having on a wide side of the conduit portion a substantially straight first wall which is substantially aligned with the series direction, the cross section also including a protruding wall formation in the conduit portion extending towards a corner on a narrow side of the conduit portion located opposite the wide side and being interested between conduit sections of the first series, with the substantially straight wall substantially coincident with a general flow direction of said primary flow conduit.

5. The assembly as claimed in claim 4, wherein the first and second series have general orientations opposing one another, the orientation of each being in common with the orientations of the protruding formation with respect to the wide side of each of their respective conduit sections.

6. The assembly as claimed in claim 4, wherein the conduit sections of the first series are interested with conduit sections of the second series.

7. The assembly as claimed in claim 1, wherein the conduit sections of the first and second series each have a second and a third side with external walls thereof shaped and arranged in such a way that:

the second side walls of the first series complement the third side walls of the second series; and

the second side walls of the second series complement the third side walls of the first series;

so as to generally provide a substantially consistent gap for the passageway there between of a layer of fluid having generally a thickness which is not substantially varying thereat.

8. The assembly as claimed in claim 1, Wherein the first and second conduit sections are straight.

9. The assembly as claimed in claim 1, wherein the conduit sections are curved.

10. The assembly as claimed in claim 1, wherein the protruding wall formation comprises two generally flat wall portions such that said cross section is substantially triangular.

11. The assembly as claimed in claim 1, wherein the protruding wall formation is substantially symmetrical about a line substantially perpendicular to the substantially flat first wall.

12. The conduit assembly as claimed in claim 1, wherein the substantially flat first walls of the first and second conduit sections are generally horizontally arranged.

13. The assembly as claimed in claim 1, wherein said first and second conduit sections each have internal walls extending therealong.

14. The assembly as claimed in claim 3, Wherein the primary flow conduit has an internal wall portion adjacent to, spaced from and substantially aligned with the substantially flat wall of one of the first or second series of elongate conduit sections.

15. The assembly as claimed in claim 14, wherein the internal wall is flat in one or more portions thereof and is parallel to the substantially flat walls of the one of of said first and second series of elongate conduit sections which is adjacent to the internal wall.

16. The conduit assembly as claimed in claim 1, wherein the conduit assembly is further mountable in the heat exchanger, which includes an elongate conduit section having an internal wall extending therealong, such that the elongate conduit section acts as a heat flow bridge from fluid in the conduit section to an external wall of the conduit section.

17. The conduit assembly as claimed in claim 1, wherein the conduit assembly is further mountable in the heat exchanger, which includes at least two adjacent conduit surfaces arranged for fluid flow therepast in a fluid flow direction, and wherein the conduit assembly further includes at least one flexible elongate spacing member located between at least one of the conduit surfaces and the conduit assembly to define a space therebetween.

18. The conduit assembly as claimed in claim 17, wherein the flexible elongate spacing member is part of a mesh, the mesh including a plurality of said flexible elongate spacing members which are interconnected by joining members.

19. The conduit assembly as claimed in claim 17, wherein said at least one flexible elongate member is generally aligned with a said fluid flow direction.

20. The conduit assembly as claimed in claim 18, wherein said joining members are elongate lengths of material and are thinner than said at least one flexible elongate spacing member.

21. The conduit assembly as claimed in claim 1, wherein the first and second series of elongate conduit sections are thermally conductive conduit sections and are extrusions composed substantially of copper or aluminium.

22. The conduit assembly as claimed in claim 21, further including at least one components made of plastic or resin and interconnecting thermally conductive conduit sections at respective ends thereof.

23. The heat exchanger assembly as claimed in claim 3, wherein the primary flow conduit and conduit sections are mutually arranged for counterflow heat exchange generally between a primary flow passing through the primary conduit and a secondary flow passing through the thermally conductive conduit sections.

24. The heat exchanger assembly as claimed in claim 3, wherein the heat exchanger assembly is positionable within a shower facility.