US20100230082A1

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Publication number: US20100230082A1
Application number: US12/403,831
Authority: US
Inventors: Chhotu Patel; Eric Schlaupitz
Original assignee: Hutchinson FTS Inc
Current assignee: Hutchinson FTS Inc
Priority date: 2009-03-13
Filing date: 2009-03-13
Publication date: 2010-09-16
Also published as: KR20100103399A; EP2228613A3; EP2228613A2

Abstract

An in-line heat exchanger comprising first and second lengths of seamless, walled tubing, the first length of tubing characterized by a larger diameter than the diameter of the second length of tubing, and the second length of walled tubing disposed within the first length of walled tubing. A plurality of longitudinally-extending channels are defined in the wall of at least one of the first and second lengths of tubing, the channels defining therebetween a plurality of longitudinally-extending passageways in the area between the walls of the first and second lengths of tubing. Terminal portions provided at opposite ends of the first length of tubing are each sealed with respect to the second length of tubing, each terminal portion defining one of an inlet or an outlet, and each terminal portion defining at least one interior passageway between the terminal portion and the wall of the second length of tubing, the at least one interior passageway communicating the plurality of longitudinally-extending passageways with one of the inlet or outlet.

Description

FIELD OF THE INVENTION

The present invention relates to tube-in-tube style, in-line heat exchangers and their manufacture.

BACKGROUND

Conventional refrigeration systems continuously circulate refrigerant in an evaporator and a condenser in a closed system such as shown in the simplified diagram ofFIG. 1. These systems have a high-pressure side (indicated by the thin lines2) and a low-pressure side (indicated by the thick lines3). Beginning at the inlet to evaporator1 and moving counter-clockwise in the direction of the arrows, a supply of low-pressure refrigerant liquid expands, absorbs heat, and evaporates, changing to a low-pressure, saturated, dry gas. Acompressor4 draws this gas from the evaporator1 through a suction line (3).Compressor4 increases the pressure of the gas, and discharges the high-pressure and high-temperature refrigerant gas to acondenser5 through a discharge line. Heat is removed from the gas at thecondenser5, which gas then condenses and becomes a high-pressure liquid. The high-pressure refrigerant liquid flows from thecondenser5 into a receiver tank6. From the receiver6 the high-pressure refrigerant liquid flows toward the evaporator1 in a pipe called the liquid line. In order for the refrigerant liquid to evaporate and cool the fluid needing refrigeration, its pressure must be reduced. This pressure reduction is achieved by passing the high-pressure refrigerant liquid through a flow restrictor (also called an expansion device). One frequently employed flow restrictor is athermal expansion valve7, or “TXV,” positioned proximate the evaporator and operative to sense both the pressure in the evaporator and, viasensor9 operatively connected (shown in dotted line) thereto, the temperature at the refrigerant vapor outlet of the evaporator. The flow of refrigerant into the evaporator1 is controlled by the degree of superheat of the suction gas.

A heat exchanger8 (depicted in dashed lines) between the liquid line and the suction line is also conventionally provided to facilitate cooling of the high-pressure and high-temperature liquid by moving it in close proximity to, and flowing oppositely of, the low-pressure and low-temperature gas drawn from the evaporator1. Conventionally, heat exchangers comprise tubing made up of concentric inner and outer tubes. According to this construction, also referred to as a tube-in-tube style heat exchanger, the high-pressure, high-temperature liquid is caused to flow through the annular space between the inner and outer tubes, while evaporated low-pressure, low-temperature refrigerant gas is caused to flow through the inside of the inner tube of the heat exchanger. The high-pressure, high-temperature liquid and the low-pressure, low-temperature gas exchange heat through the inner tube, whereby the high-pressure, high-temperature liquid is cooled. This heat transfer process of the high-pressure and high-temperature liquid increases the sub-cooling thereof.

Conventional tube-in-tube style heat exchangers are, unfortunately, complex in construction and therefore costly to manufacture. Exemplary in these regards are the heat exchanger tubes disclosed in Usui, U.S. Pat. No. 7,044,210, and McLain, U.S. Pat. No. 3,831,675. It would therefore be desirable to have a tube-in-tube style heat exchanger that is easy and inexpensive to manufacture, and which allows efficient heat transfer between the inner and outer tubes thereof.

SUMMARY OF THE INVENTION

According to the specification, there is disclosed an in-line heat exchanger, comprising first and second lengths of seamless, walled tubing, the first length of tubing characterized by a larger diameter than the diameter of the second length of tubing, and the second length of walled tubing disposed within the first length of walled tubing. A plurality of longitudinally-extending channels defined in the wall of at least one of the first and second lengths of tubing, the channels defining therebetween a plurality of longitudinally-extending passageways in the area between the walls of the first and second lengths of tubing. Terminal portions provided at opposite ends of the first length of tubing are each sealed with respect to the second length of tubing, and each defines one of an inlet or an outlet. Each terminal portion further defines at least one interior passageway between the terminal portion and the wall of the second length of tubing, the at least one interior passageway communicating the plurality of longitudinally-extending passageways with one of the inlet or outlet.

In one embodiment, the terminal portions are each defined by opposite ends of the first length of tubing that are sealed against the wall of the second length of tubing. In another embodiment, the terminal portions comprise separate lengths of tubing that are connected to each of the first and second lengths of tubing.

According to one feature hereof, the terminal portions may have different longitudinal dimensions with respect to each other so as to define interior passageways of different volumes. Furthermore, one of the terminal portions may define an interior passageway capable of accommodating an amount of a high-pressure, sub-cooled fluid at least equivalent to the weight of the quantity of a high-pressure fluid that can be accommodated in the receiver dryer in a fully-charged air-conditioning system.

Per one aspect of the invention, the plurality of longitudinally-extending channels are defined in only the wall of the first length of tubing. However, the plurality of longitudinally-extending channels may, alternatively, be defined in the wall of only the second length of tubing, or in the walls of both of the first and second lengths of tubing.

According to another aspect of the invention, the plurality of longitudinally-extending channels comprise at least two discrete sets of longitudinally-extending channels. Each discrete set of channels may, moreover, be separated from the other by an intermediate space defined in the area between the walls of the first and second lengths of tubing. Per another feature of the invention, at least one such discrete set of channels may be offset relative to the one or more other sets of channels.

Per still another feature, the plurality of longitudinally-extending channels may each define a helical path.

The specification further discloses an exemplary method for forming such tube-in-tube style, in-line heat exchangers, the method comprising the steps of:

providing at least first and second lengths of seamless, walled tubing, the first length of tubing characterized by a larger diameter than the diameter of the second length of tubing, and each of the at least first and second lengths of walled tubing characterized by generally circular cross-sectional shapes;

inwardly deforming circumferentially spaced-apart portions of the wall of at least one of the first and second lengths of tubing to form along a longitudinal length thereof a plurality of longitudinally-extending channels; and

positioning the second length of walled tubing within the first length of walled tubing so that the walls of the first and second lengths of tubing are in contact proximate the plurality of longitudinally-extending channels, and so that, intermediate the areas of contact between the first and second lengths of walled tubing proximate the plurality of longitudinally-extending channels there are defined between the walls of the first and second lengths of tubing a plurality of longitudinally-extending passageways.

In another embodiment thereof, the method for forming in-line heat exchangers comprises the ordered steps of:

positioning the second length of walled tubing within the first length of walled tubing; and

deforming inwardly circumferentially spaced-apart portions of the wall of the first length of tubing to bring the same into contact with the wall of the second length of tubing, thereby forming along a longitudinal length of the tubing a plurality of longitudinally-extending channels in the wall of the first length of tubing, the plurality of longitudinally-extending channels defining therebetween a plurality of longitudinally-extending passageways between the walls of the first and second lengths of tubing.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, which show exemplary embodiments of the present invention, and in which:

FIG. 1 is a simplified diagram of a conventional air-conditioning system;

FIG. 2A is a lateral elevational view of a heat exchanger in accordance with an exemplary embodiment of the invention;

FIG. 2B is a cross-sectional view of the heat exchanger ofFIG. 2A;

FIG. 3 is a lateral elevational view of a heat exchanger in accordance with a second exemplary embodiment of the invention;

FIG. 4 is a simplified schematic depicting the heat exchanger ofFIG. 3 in an exemplary operational environment;

FIG. 5 is a lateral elevational view of a heat exchanger in accordance with a third exemplary embodiment of the invention;

FIG. 6 is a lateral elevational view of a heat exchanger in accordance with a fourth exemplary embodiment of the invention;

FIG. 7 is a lateral elevational view of a heat exchanger in accordance with a fifth exemplary embodiment of the invention;

FIG. 8 is a cross-sectional view of a heat exchanger in accordance with an alternative construction;

FIG. 9 is a cross-sectional view of a heat exchanger in accordance with an alternative construction;

FIG. 10 is a perspective view of an exemplary forming apparatus for making heat exchangers in accordance with the present invention; and

FIGS. 11A and 11B are cross-sectional view of the press portion of the apparatus ofFIG. 10, depicting the step of forming channels in the walled tubing comprising the heat exchanger.

DETAILED DESCRIPTION

As required, a detailed embodiment of the present invention is disclosed herein. However, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The accompanying drawings are not necessarily to scale, and some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

Referring now to the drawings, wherein like numerals refer to like or corresponding parts throughout the several views, the present invention is characterized, according to a first embodiment thereof, as a tube-in-tube style, in-line heat exchanger (identified generally at10) comprising first20 and second30 lengths of walled tubing arranged with thesecond length30 of tubing disposed within the inner diameter of thefirst length20 of tubing.FIGS. 2A and 2B. While generally described herein in connection with air conditioning systems, it will be understood by those skilled in the art that the heat exchanger of the present invention may be incorporated in any system employing a two-phase refrigerant fluid.

As shown best inFIG. 2B, thesecond length30 of tubing is characterized by a generally circular cross-section, with thearea31 defined by the inner diameter defining a passageway for the flow of a low-pressure, low-temperature fluid, such as a refrigerant gas, therethrough. Thefirst length20 of tubing is characterized by a corrugated or wavy cross-section defined by a plurality of circumferentially spaced-apart, longitudinally-extendingchannels21. Proximate the nadir of eachsuch channel21, the inner surface of the wall of the outer,first length20 of tubing is in contact with the exterior surface of the wall of the inner,second length30 of tubing. Intermediate thechannels21 is defined in the annular space between the first20 and second30 lengths of tubing a plurality of longitudinally-extendingpassageways40, each such passageway closed off from the other by reason of the contact between the interior of the wall of first length oftubing20 and the exterior of the wall of the second length oftubing30. Eachpassageway40 defines an internal channel for the flow of a high-pressure fluid, such as a high-pressure liquid, therethrough in a direction opposite the direction of the low-pressure fluid flow through theinner diameter31 of the second length oftubing30.

Referring particularly toFIG. 2A, the heat exchanger according to the illustrated embodiment will, in order to be integrated in-line into a refrigeration system (such as depicted in schematically inFIG. 3) or other operational environment, include

terminal portions

22a,22bdisposed exteriorly of, and sealed with respect to, the second length oftubing30, as shown inFIG. 2A (where the second length oftubing30 is shown in dashed lines). Each

terminal portion

22a,22bcommunicates a

passageway

23a,23b,respectively, defining one of an inlet or an outlet for a high-pressure fluid (such as for a high-pressure liquid in a vehicle air-conditioning system) with, respectively, at least one

interior passageway

24aor24b(such as, for instance, a circumferential space) defined in the area between the terminal portion and the wall of the second length oftubing30. Wherepassageway23adefines the inlet,interior passageway24acommunicates the high-pressure fluid from the inlet to thepassageways40, while thepassageway23bcommunicates the high-pressurefluid exiting passageways40 to the outlet defined (in this example) by thepassageway23b.

As those skilled in the art will appreciate, the number ofpassageways40 and their individual cross-sectional dimensions, as well as the dimensions of theinner diameter31 of the second length oftubing30, and the thickness of the walls of each of the first20 and second30 lengths of tubing will vary in accordance with the type of two-phase fluids employed in, and other known operating parameters of, the system. Generally speaking, however, it is contemplated that the number ofpassageways40 and their individual cross-sectional dimensions will correspond to the cross-sectional dimensions of the

interior passageways

24aor24bdefined in the area between the

terminal portions

22a,22b,respectively, and the exterior of the wall of the second length oftubing30.

It will also be understood by those skilled in the art that the length of the active heat-transfer area—that is, the length of the portion of heat-exchanger10 comprisingchannels21 and correspondingpassageways40—will vary according to the particular parameters (e.g., air conditioner size and cooling load) of the system in which it is incorporated. Furthermore, while theheat exchanger10 depicted in the several embodiments disclosed herein is straight, it will be understood that the tubing may be bent—typically along the length of the active heat transfer surface—as required to accommodate the physical limitations of the space in which theheat exchanger10 is disposed, to make necessary connections between the opposite ends of the second length oftubing30, etc. And, in practice, the heat exchanger as disclosed herein has demonstrated the ability to be bent in multiple locations without collapsing thepassageways40.

As depicted, the second length oftubing30 extends beyond the

terminal portions

22a,22b.The length of these extensions will vary according to the particular application and, in any known manner, the opposite free ends of thesecond length30 of tubing may be secured to upstream and downstream components in the system in which the heat-exchanger is employed.

With continuing reference toFIG. 2A, it is contemplated that the

terminal portions

22a,22bmay, as shown, be formed from terminal sections of the first length oftubing20 that are not formed with channels21 (so that the high-pressure fluid can move freely from the inlet into each of thepassageways40 and, at the opposite end of each of thesepassageways40, may likewise move freely to the outlet). This may be accomplished, for example, by crimping the

ends

25a,25bagainst the second length oftubing30. The crimped ends25a,25bmay be brazed or otherwise sealed by conventional means against thetubing30 so that high-pressure fluid is able to move only between the inlet and outlets of

terminal portions

22a,22b.

Alternatively, it is contemplated that the terminal portions may comprise separate lengths of tubing that are connected to each of the first and second lengths of tubing.

While a variety of materials may be employed for the heat exchanger of the present invention, including for the first20 and second30 lengths of tubing, suitable exemplary materials include metals such as steel, stainless steel, aluminum, aluminum base, copper, copper base alloys and nickel and nickel base alloys.

Referring next toFIGS. 3 and 4, there is shown an alternative embodiment wherein theheat exchanger10′ is characterized byterminal portions22a′,22b′ of dissimilar longitudinal dimensions. More particularly, the terminal portion at which the outlet is defined (22b′ in the illustrated example) has relatively greater longitudinal dimensions than the terminal portion at which the inlet is defined (22a′ in the example). The longitudinal dimension ofterminal portion22b′ is such that the volume of theinterior passageway24b′ defined in the area between theterminal portion22b′ and the exterior of the wall of the second length oftubing30′ is capable of accommodating, by weight (e.g., in grams), an amount of high-pressure, high-temperature fluid at least equivalent to the weight (e.g., in grams) of the quantity of high-pressure, high-temperature fluid that can be accommodated in the receiver dryer (whether integrated with the condenser or of the stand-alone type) in a fully-charged vehicle air conditioning system. Referring specifically toFIG. 4, it will further be noted that the outlet to thethermal expansion valve7 is oriented to provide gravity feed of sub-cooled, high-pressure fluid thereto. Such orientation in particular serves to reduce noise at the thermal expansion valve.

By the foregoing, the inventive heat exchanger provides a fluid storage capability and, moreover, the sub-cooled fluid metered to thethermal expansion valve7 is characterized by a lower pressure drop than in conventional systems. This improves vehicle fuel economy (when employed in a vehicle air-conditioning system), increases the cooling capacity of the evaporator, and permits relocation or even removal of the receiver dryer or integrated receiver found in conventional vehicle air-conditioning systems.

While, according to the aforedescribed embodiments, the

channels

21,21′ (and

corresponding passageways

40,40′) are depicted as being continuous for the length of the active heat-transfer area, it will be understood that they may be alternatively configured. Thus, for instance, it is contemplated that, according to the embodiment ofFIG. 5,heat exchanger10″ may have formed therein a plurality of longitudinallydiscontinuous channels21a″,21b″ that are interrupted one or more times along the length of thetubing20″ to define therebetween, and in the area between the first20″ and second30″ lengths of tubing, one or moreintermediate spaces41″ in which high-pressure, high-temperature fluid exiting thepassageways40a″ would flow before entering further,downstream passageways40b″. It will be understood that suchintermediate spaces41″ beneficially facilitate mixing of the fluid flowing therein.

Alternatively, in another embodiment of theheat exchanger10′″ (FIG. 6), thechannels21a′″,21b′″,21c′″ are longitudinally discontinuous, being interrupted by one or moreintermediate spaces41a′″,41b′″, with the successive set ofchannels21b′″,21c′″ (and, therefore, downstream passageways, e.g.,40b′″,40c′″) being offset relative to each preceding set ofchannels21a′″,21b′″ (and, therefore, upstream passageways, e.g.,40a′″,40b′″). As shown theintermediate spaces41a′″,41b′″ of this embodiment are of shorter longitudinal dimensions than those of the embodiment ofFIG. 5. It will be appreciated that the length of such intermediate spaces may be varied as desired, subject only to the provision that fluid flowing through one set of upstream passageways be able to continue flowing into successive downstream passageways.

It will also be appreciated that any number of sets of such discontinuous channels, whether aligned or offset, may be provided, depending upon the length of the channels in such sets and the overall length of the heat exchanger.

According to a still further embodiment of theheat exchanger10″″ of the present invention, shown inFIG. 7, thechannels21″″ may be formed so as to each define a helical path along the length of the first length oftubing20″″ between theterminal portions22a″″,22b″″. Optionally, theheat exchanger10″″ of this embodiment may be further characterized by longitudinally discontinuous channels, such as exemplified in foregoing embodiments, and one or more intermediate spaces (not shown) disposed therebetween.

While, in each of the aforedescribed embodiments, the plurality of longitudinally-extending

channels

21,21′,21″, etc. are shown as being defined in the wall of the first length of

tubing

20,20′,20″, etc., it is contemplated that these channels may, alternatively, be defined in the second length of

tubing

30,30′,30″, etc., such as depicted inFIG. 8, or even on both lengths of tubing, such as shown inFIG. 9.

Referring next toFIGS. 10 through 11B, the exemplary method by which the heat exchangers as heretofore described may be manufactured will be better understood.

According to the illustrated embodiment, there is provided a forming apparatus (indicated generally at100) essentially comprising an hydraulically-actuatedpress101 and an hydraulically-actuatedcarriage assembly120.Press101 more particularly comprises a stationary, split-ring element102 supporting a plurality ofrollers103 arranged circumferentially, and equidistant from each other, about acentral opening104 which, in operation of the apparatus, is occupied by one or both of the first20 and second30 lengths of tubing. The relative distance between eachroller103 corresponds to the dimensions of the plurality ofpassageways40 to be formed in the tubing. While, in the illustrated embodiment, eightsuch rollers103 are depicted, it will be understood that the number may be varied according to the desired number, and dimensions, of thechannels21 and correspondingpassageways40.

Rollers

103 are each disposed onsupport members105 riding in, and reciprocally moveable with respect to,radial openings106 defined in thering element102. As shown best inFIG. 9, eachsupport member105 has an angled cam-followingsurface107 corresponding approximately in shape to theangled surface108 ofcam member109.Cam member109 defines a ring-like shape of greater diameter than the split-ring element102.Cam member109 is hydraulically reciprocally-moveable along an axis coaxial with the central axis of split-ring element102 so as to selectively move theangled surface108 thereof into and out of engagement with the co-acting, cam-followingsurfaces107.

With reference particularly toFIG. 9,carriage assembly120 comprises amechanical grip121, such as, for example, a chuck, in theopening122 of which are fixedly retained first20 and/or second30 lengths of tubing.Mechanical grip121 is secured to asled123 that rides, under power of anhydraulic piston125, freely along rails124.

Referring also toFIGS. 9A and 9B, there are provided in operation of the aforedescribed apparatus first20 and second30 lengths of cylindrical, walled tubing arranged with the second length oftubing30 disposed within the first20. The

tubes

20,30 so arranged are fixed in position within opening122 of themechanical grip121 so that a length of the

tubes

20,30 extends from thegrip121 in the direction of thepress101. As noted, at this stage both the first20 and second30 lengths of tubing are characterized by generally circular cross-sections, as shown inFIG. 9A, thefirst length20 having an inside diameter larger than the outer diameter of thesecond length30 of tubing so that, when the lengths of tubing are arranged one within the other, an annular space is defined between the exterior and interior surfaces of the walls thereof.

Subsequently, thesled123 is moved by operation of thepiston125 in the direction of thepress101 so as to position the

tubing

20,30 in thecentral opening104.FIG. 9A. At the desired position along the length of the

tubing

20,30, and as the tubing is continually urged through thecentral opening104 by corresponding movement of thesled123, thecam member109 is moved over the split-ring element102 so as to bring theangled surface108 into engagement with cam-followingsurfaces107 of thesupport members105. By the co-action of these

surfaces

107,108, eachsupport member105 is driven radially inward into its respectiveradial opening106 until therollers103 are brought into contact with the exterior surface of thefirst length20 of tubing to form the longitudinally-extendingchannels21 heretofore described. More particularly, as the pressure applied byrollers103 increases, the wall of thefirst length20 of tubing is locally deformed in the area of each deforming member60.FIG. 9B. The pressure applied by eachroller103 is sufficient to inwardly deform the wall of thefirst length20 of tubing proximate thereto until the wall has been urged inwardly to the point where the interior surface thereof is in contact with the exterior surface of the wall of thesecond length30 of tubing. As the tubing continues to be urged through thecentral opening104 by corresponding movement of thesled123, this deforming pressure continues, thus forming channels21 (and the corresponding passageways40) of lengths determined by the duration of operation of the forming apparatus.

The amount of deforming pressure applied will, naturally, vary with the material of the first20 and second30 lengths of tubing; however, the amount of deforming pressure will at least be sufficient to bring the interior surface of the wall of thefirst length20 of tubing into contact with the exterior surface of thesecond length30 of tubing so as to form the plurality ofchannels21 and, correspondingly, the plurality ofpassageways41 between the first and second lengths of tubing.

It will be appreciated that, by the foregoing method of construction, the inventive heat exchangers may be fashioned from seamless tubing, rather than being formed from sheets of material that are first formed to include the plurality of channels and then joined end-to-end to define tubular shapes.

According to the aforedescribed methodology, it will be appreciated that the several embodiments of heat exchangers as described herein may be formed by modifying the manner of operation of the forming apparatus. For instance, the formation ofdiscontinuous channels21 may be accomplished by selectively moving thecam member109 away from the split-ring element102 while the tubing is being moved through thecentral opening104 so as to temporarily disengage theangled surfaces108 from cam-followingsurfaces107, thereby eliminating the deforming pressure applied by therollers103. Relatedly, the formation along the length of the heat exchanger of offset channels may be accomplished by rotating by a predetermined amount the lengths of

tubing

20,30 within thegrip121 before bringing theangled surfaces108 of thecam member109 back into engagement with the cam-followingsurfaces107. And relative to the embodiment herein described wherein the channels extend along a helical path, it will be appreciated that such a configuration may be accomplished by rotating the lengths of

tubing

20,30 within thegrip121 simultaneously with both the continued movement of the tubing through thecentral opening104 by corresponding movement of thesled123 and the application of deforming pressure by thepress101 as heretofore described.

It will be understood that, according to the aforedescribed methodology, the formation of a heat exchanger wherein the inner, second length oftubing30 is formed to includechannels21 will necessitate first forming such channels on the second length of tubing in the formingapparatus100 and then disposing that length of tubing within the first length oftubing20; the exemplary formingapparatus100 as described does not permit disposing the second length oftubing30 within the first20, and then formingchannels21 on the second length oftubing30.

It will be appreciated that the cross-sectional shape ofchannels21 may be varied by varying the cross-sectional shape of therollers103 employed.

The foregoing description of the exemplary embodiments of the invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the innovation. The embodiments shown and described in order to explain the principals of the innovation and its practical application to enable one skilled in the art to utilize the innovation in various embodiments and with various modifications as are suited to the particular use contemplated. Although only a limited number of embodiments of the present innovations have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible without materially departing from the novel teachings and advantages of the subject matter recited. Accordingly, all such modifications are intended to be included within the scope of the present innovations. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the spirit of the present innovations.

Claims

1. An in-line heat exchanger, comprising:

first and second lengths of seamless, walled tubing, the first length of tubing characterized by a larger diameter than the diameter of the second length of tubing, and the second length of walled tubing disposed within the first length of walled tubing;

a plurality of longitudinally-extending channels defined in the wall of at least one of the first and second lengths of tubing, the channels defining therebetween a plurality of longitudinally-extending passageways in the area between the walls of the first and second lengths of tubing; and

terminal portions provided at opposite ends of the first length of tubing, the terminal portions each sealed with respect to the second length of tubing and each defining one of an inlet or an outlet, and each terminal portion defining at least one interior passageway between the terminal portion and the wall of the second length of tubing, the at least one interior passageway communicating the plurality of longitudinally-extending passageways with one of the inlet or outlet.

2. The heat exchanger ofclaim 1, wherein the terminal portions are each defined by opposite ends of the first length of tubing that are sealed against the wall of the second length of tubing.

3. The heat exchanger ofclaim 1, wherein the terminal portions comprise separate lengths of tubing that are connected to each of the first and second lengths of tubing.

4. The heat exchanger ofclaim 1, wherein the terminal portions have different longitudinal dimensions with respect to each other so as to define interior passageways of different volumes.

5. The heat exchanger ofclaim 4, wherein one of the terminal portions defines an interior passageway capable of accommodating an amount of a high-pressure, sub-cooled fluid at least equivalent to the weight of the quantity of a high-pressure fluid that can be accommodated in the receiver dryer in a fully-charged air-conditioning system.

6. The heat exchanger ofclaim 1, wherein the plurality of longitudinally-extending channels are defined in the wall of the first length of tubing.

7. The heat exchanger ofclaim 1, wherein the plurality of longitudinally-extending channels are defined in the wall of the second length of tubing.

8. The heat exchanger ofclaim 1, wherein the plurality of longitudinally-extending channels are defined in the walls of both the first and second lengths of tubing.

9. The heat exchanger ofclaim 1, wherein the plurality of longitudinally-extending channels comprise at least two discrete sets of longitudinally-extending channels.

10. The heat exchanger ofclaim 9, wherein each discrete set of channels is separated from the other by an intermediate space defined in the area between the walls of the first and second lengths of tubing.

11. The heat exchanger ofclaim 9, wherein at least one discrete set of channels is offset relative to the one or more other sets of channels.

12. The heat exchanger ofclaim 11, wherein each discrete set of channels is separated from the other by an intermediate space defined in the area between the walls of the first and second lengths of tubing.

13. The heat exchanger ofclaim 1, wherein the plurality of longitudinally-extending channels each define a helical path.

14. A method for forming in-line heat exchangers, comprising the steps of:

15. The method ofclaim 14, wherein the step of positioning the second length of walled tubing within the first length of walled tubing is carried out before the step of inwardly deforming circumferentially spaced-apart portions of the wall of at least one of the first and second lengths of tubing.

16. The method ofclaim 15, wherein the step of inwardly deforming circumferentially spaced-apart portions of the wall of at least one of the first and second lengths of tubing comprises inwardly deforming circumferentially spaced-apart portions of the wall of the first length of tubing.

17. The method ofclaim 14, wherein the step of positioning the second length of walled tubing within the first length of walled tubing is carried out after the step of inwardly deforming circumferentially spaced-apart portions of the wall of at least one of the first and second lengths of tubing.

18. The method ofclaim 17, wherein the step of inwardly deforming circumferentially spaced-apart portions of the wall of at least one of the first and second lengths of tubing comprises inwardly deforming circumferentially spaced-apart portions of the wall of the second length of tubing.

19. The method ofclaim 17, wherein the step of inwardly deforming circumferentially spaced-apart portions of the wall of at least one of the first and second lengths of tubing comprises inwardly deforming circumferentially spaced-apart portions of the walls of the first and second lengths of tubing.

20. The method ofclaim 14, wherein the step of inwardly deforming circumferentially spaced-apart portions of the wall of at least one of the first and second lengths of tubing to form along a longitudinal length thereof a plurality of longitudinally-extending channels further comprises forming those channels intermediate of terminal sections of the first length of tubing, and wherein the method further comprises the step of sealing the ends of the terminal sections against the wall of the second length of tubing to define terminal portions each defining at least one interior passageway between the terminal portion and the wall of the second length of tubing, the at least one interior passageway communicating the plurality of longitudinally-extending passageways, and the step of forming one of an inlet or outlet passageway in each terminal section, the inlet and outlet each communicating one or the other of the at least one interior passageways defined in each terminal portion.

21. The method ofclaim 20, wherein the terminal portions have different longitudinal dimensions with respect to each other so as to define interior passageways of different volumes.

22. The method ofclaim 21, wherein one of the terminal portions defines an interior passageway capable of accommodating an amount of a high-pressure, sub-cooled fluid at least equivalent to the weight of the quantity of a high-pressure fluid that can be accommodated in the receiver dryer in a fully-charged air-conditioning system.

23. The method ofclaim 17, wherein the plurality of longitudinally-extending channels comprise at least two discrete sets of channels, each discrete set of channels comprising a plurality of longitudinally-extending channels.

24. The method ofclaim 23, wherein each such discrete set of channels is separated from the other by an intermediate space defined in the area between the walls of the first and second lengths of tubing.

25. The heat exchanger ofclaim 23, wherein at least one discrete set of channels is offset relative to the one or more other discrete sets of channels.

26. The method ofclaim 25, wherein each such discrete set of channels is separated from the other by an intermediate space defined in the area between the walls of the first and second lengths of tubing.

27. The heat exchanger ofclaim 14, wherein the plurality of longitudinally-extending channels each define a helical path.

28. A method for forming in-line heat exchangers, comprising the ordered steps of:

29. The method ofclaim 28, wherein the step of inwardly deforming circumferentially spaced-apart portions of the wall of the first length of tubing to form along a longitudinal length thereof a plurality of longitudinally-extending channels further comprises forming those channels intermediate of terminal sections of the first length of tubing, and wherein the method further comprises the step of sealing the ends of the terminal sections against the wall of the second length of tubing to define terminal portions each defining at least one interior passageway between the terminal portion and the wall of the second length of tubing, the at least one interior passageway communicating the plurality of longitudinally-extending passageways, and the step of forming one of an inlet or outlet passageway in each terminal section, the inlet and outlet each communicating one or the other of the at least one interior passageways defined in each terminal portion.

30. The method ofclaim 29, wherein the terminal portions have different longitudinal dimensions with respect to each other so as to define interior passageways of different volumes.

31. The method ofclaim 30, wherein one of the terminal portions defines an interior passageway capable of accommodating an amount of a high-pressure, sub-cooled fluid at least equivalent to the weight of the quantity of a high-pressure fluid that can be accommodated in the receiver dryer in a fully-charged air-conditioning system.

32. The method ofclaim 28, wherein the plurality of longitudinally-extending channels comprise at least two discrete sets of channels, each discrete set of channels comprising a plurality of longitudinally-extending channels.

33. The method ofclaim 32, wherein each such discrete set of channels separated from the other by a circumferential chamber defined in the area between the walls of the first and second lengths of tubing.

34. The method ofclaim 32, wherein at least one discrete set of channels is offset relative to the one or more other discrete sets of channels.

35. The heat exchanger ofclaim 28, wherein the plurality of longitudinally-extending channels each define a helical path.