US20060081362A1

US20060081362A1 - Finned tubular heat exchanger

Info

Publication number: US20060081362A1
Application number: US10/967,810
Authority: US
Inventors: Homayoun Sanatgar; Gary Johnson; Neil Holt; Don Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-10-19
Filing date: 2004-10-19
Publication date: 2006-04-20

Abstract

An apparatus and method for fabricating an externally finned tubular heat exchanger assembly comprising two concentric thin walled tubular members defining therebetween an intermediate inner annular fluid flow channel, and positionally fixed therewithin an internal turbulizer strip extending longitudinally in a helical spiral. The tubulizer strip is embossed with corrugations prior to installation into the intermediate inner annular fluid flow channel. The corrugated strip is helically spiraled with sequential bridge gap spaces between adjacent serial turns wherein the corrugations form a series of triangular cross-sectional fluid flow passageways. Turbulizer corrugation expansion, after insertion into the inner intermediate annular fluid flow channel, mechanically anchors the corrugated turbulizer strip to the second inner concentric tubular member that has an end groove to provide engagement connection. The turbulizer is utilized to vary conductance and thus control fluid flow through the tubular inner channel of the second concentric tubular member. External fins are attached to the exterior circumferential surface of the first outer concentric tubular subassembly member to further enhance heat exchange.

Description

FIELD OF THE INVENTION

The present invention relates generally to the field of heat exchangers, and more particularly to finned concentric tubular member heat exchangers.

BACKGROUND OF THE INVENTION

The prior art relates to heat exchangers formed by finned concentric thin walled tubular members defining an intermediate inner annular fluid flow channel therebetween containing a corrugated, helical spirally formed turbulizer strip initially pre-assembled in a prestressed coiled condition and inserted longitudinally into the intermediate inner annular fluid flow channel formed between the two concentric thin walled tubular members.
While concentric tubular thin walled heat exchanger assemblies are well known in the field and generally provide efficient and effective heat exchange between the fluid flow channel through the center of the concentric inner tubular member and that of a secondary fluid flow confined in the intermediate inner annular fluid flow channel between the paired tubular members, or between a fluid confined between the two paired tubular members and a fluid flow external to the outer tubular member, it has been determined that the heat transfer can be enhanced by improving the heat exchanger flow characteristics within the intermediate inner annular fluid flow channel by providing therein a helical spirally formed, corrugated turbulizer strip anchored to the second inner concentric thin walled tubular member to vary inner fluid flow conductance.
This turbulizer structure is pre-fabricated during heat exchanger assembly by first applying a predetermined compressive force to the helical, spirally formed turbulizer corrugated strip member so that the turbulizer member is compressed prior to insertion, and then inserted into the fixed confinement within the intermediate inner annular fluid flow channel under the initial pre-stressed compressive force. The turbulizer peaks and valleys then expand to improve contact with the surrounding circumferential surfaces to enhance the efficiency of the heat exchanger. Improvements of the concentric tubular design of pre-existing heat exchangers is desired, as shown in the herein disclosed, invention, to achieve improved heat transfer and heat exchanger versatility.

SUMMARY

An improved finned tubular heat exchanger assembly comprises an externally finned subassembly in combination with concentrically spaced-apart, thin walled tubular member subassemblies having therebetween an intermediate inner annular fluid flow channel containing an inner turbulizer subassembly. The first outer concentric thin wall tubular member subassembly has a larger inside circumference than the second inner concentric thin walled tubular member subassembly with a smaller outer circumference. The intermediate inner annular fluid flow channel, formed between the heat exchanger first and second concentric thin walled tubular members, defines the sidewalls of the intermediate inner annular fluid flow channel which is coincident with portions of the internal circumferential flow area of the first outer concentric thin walled tubular member subassembly.
The finned tubular heat exchanger assembly has contained therewithin, along its internal longitudinal axis, at least one intermediate inner annular fluid flow channel. A helical, spiral uniformly wound, corrugated turbulizer strip is concentrically secured within the intermediate inner annular fluid flow channel and is positioned in the form of a helical space-gapped spiral that is longitudinally fixed axially and radially to the second concentric thin walled tubular member that defines the smaller circumferential internal sidewall of the intermediate inner annular fluid flow channel to thermally enhance heat transfer by interconnecting together both the inner circumferential area surface of the outer concentric thin walled tubular member and the outer circumferential area of the smaller second inner concentric thin walled tubular member subassembly.
In addition to imparting good thermal conduction contact with the second concentric thin walled tubular member surface, the turbulizer strip subassembly is structurally designed and positioned to vary the internal cross-sectional flow area of the second concentric thin walled tubular subassembly member and provides additional control of inner concentric tubular fluid flow through the heat exchanger.
The spiral turbulizer strip subassembly has corrugations with triangular cross-sectional areas and is constructed from a heat conductive material formed in a predetermined configuration to produce turbulization mixing of the fluid flow passing along and through the longitudinal triangular corrugations of the turbulizer strip subassembly. Fluid flow is confined in the heat exchanger between the intermediate inner annular fluid flow channel sidewalls to generate desired fluid turbulization as the fluid flows through the intermediate inner annular fluid flow channel formed between the inner circumferential surface of the first outer concentric thin walled tubular member and the outer circumferential surface of the second inner concentric thin walled tubular member, and also along the surfaces of the helical spiraled corrugated turbulizer strip, thereby enhancing fluid heat transfer and increasing thermal efficiency of the heat exchanger.
The turbulizer strip corrugated cross-section triangular shaped longitudinal channels are smooth surfaced to reduce resistance to flow through the channels, and the fluid flow entering each corrugation passageway entrance is directed to and across the turbulizer spiral bridge space-gap to cause the downstream flow exiting from each proceeding corrugation flow channel to cross-mix and impinge upon and enter opposing passageway edges after exiting each succeeding corrugation, then promoting cross mixing across the turbulizer spiral gap before entering each succeeding series of downstream longitudinal corrugations.
The corrugated turbulizer strip of the present invention extends spirally within the intermediate inner annular fluid flow channel, the corrugations having ridge peaked apexes and valley bottom bases, defining flattened tubular contact areas adjacent to the intermediate inner annular fluid flow channel side wall lines of contact between the corrugation sidewalls and the peripheries of the first outer concentric thin walled tubular member inner circumference and the second concentric thin walled tubular member outer circumference that collectively define sidewall boundaries of the intermediate inner annular fluid flow channel.
The corrugated strip turbulizer directs the fluid flow leaving a first preceding triangular corrugation to axially flow across the spiral bridge space-gap formed between succeeding subsequent triangular longitudinal corrugations, promoting cross-mixing of fluid flow streams exiting preceding spiral corrugation passageways and then crossing the bridge space-gap separation areas between each of the succeeding spiral corrugated turbulizer flow passageways.
The fluid flow conductance through the heat exchanger is varied by preselecting the desired second inner concentric tubular member cross-sectional area to produce the desired dynamic flow characteristics required for satisfying the heat transfer requirements of a specific fluid heat source. By varying the internal cross-sectional area of the second inner concentric thin walled tubular subassembly, such as by the turbulizer anchor end, crimping, or by other means reducing the internal diameter of the second concentric thin walled tubular member. Thus resistance to fluid flow resulting from cross-sectional flow area restriction is varied by the turbulizer anchor connection configuration.
The finned tubular heat exchanger is thus fabricated by concentrically spacing apart two concentric tubular members to define an intermediate inner annular fluid flow channel chamber to place therewithin a turbulizer strip of corrugated sheet metal to extend longitudinally and spirally within the intermediate inner annular fluid flow channel. Adjacent spiral turns of the corrugated spirally formed strip are bridge gap-spaced apart from each other to provide a parallel series of individual longitudinal triangular passageways to define the triangular cross-section channel discharge exits discharging fluid flow between the side edges of each series of adjacent corrugated spiral turn produced parallel passageways. When fluid discharge from each preceding triangular corrugation channel discharges fluid flow across the corrugation spiral turbulizer bridge space-gap, that fluid flow is also directed into the triangular entrance passageways so that the fluid flow enters each succeeding turbulizer corrugated passageway and promotes efficient heat transfer.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred exemplary embodiment of the invention will hereinafter be described in conjunction with the appended drawings.
FIG. 1 is an axial cross-sectional view of one embodiment of the present invention.
FIG. 2 is a cross-sectional end view of a portion of the embodiment of FIG. 1.
FIG. 3 is a plan view of a corrugated turbulizer subassembly member after corrugation.
FIG. 4 is a cross-sectional end view of the turbulizer subassembly member along line 4-4 of FIG. 3.
FIG. 5 is a cross-sectional side view of a portion of the turbulizer member after insertion.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1, 2, 4, and 5 of the drawings, there is shown an improved finned concentric thin walled tubular member heat exchanger assembly 10 comprised of an external finned subassembly, a first outer concentric thin walled tubular subassembly member 20 having a first larger inside circumference 25, a second inner concentric thin walled tubular subassembly member 40 having a second smaller outside circumference 45, and having formed therebetween the two tubular members a longitudinal intermediate inner annular flow channel axial region 60, within which is positioned an internal turbulizer subassembly member 70 being formed as a corrugated strip with triangular cross-sectional area passageways 72 that extend spiral axially within the intermediate inner annular flow channel axial region member 60 between the first outer concentric thin walled tubular subassembly member 20 having a larger inside circumference 25 and the second inner concentric thin walled tubular subassembly member 40 having the smaller outside diameter 45. The first outer concentric thin walled tubular subassembly member 20 has externally attached thereto a plurality of longitudinally spaced transverse exterior rippled fins 102 forming an external rectangular fin subassembly 100 that radiate or absorb heat from surrounding areas to provide efficient heat transfer to the heat exchanger fluid flowing through the axial intermediate inner annular flow channel axial region 60 defined between the first outer concentric thin walled tubular subassembly member 20 and the second inner concentric thin walled tubular subassembly member 40.
As shown in FIGS. 4 and 5, the internal turbulizer subassembly member 70 is preformed prior to placement in the longitudinal intermediate inner annular flow channel axial region 60 by pressing it onto the second inner concentric thin walled tubular subassembly member 40, or otherwise compressed for helical insertion between the first outer concentric thin walled tubular subassembly member 20 and second inner concentric thin walled tubular subassembly member 40, within the intermediate inner annular flow channel axial region member 60.
In one method of fabrication, the second inner concentric thin walled tubular subassembly member 40 having a smaller outside circumference 45 may be expanded slightly so as to compress the turbulizer assembly corrugations between the outer periphery of the second inner concentric thin walled tubular subassembly member 40 having a smaller outside circumference 45 and the inner periphery of the first outer concentric thin walled tubular subassembly member 20 having a larger inside circumference 25. Mechanical anchor locking of the internal turbulizer subassembly member 70 positionally between the first outer concentric thin walled tubular subassembly member 20 having a larger inside circumference 25 and the second inner concentric thin walled tubular subassembly member 40 having a smaller outside circumference 45 is achieved by mechanically forcing a mandrel of slightly larger circumference than the external circumference of the second inner concentric thin walled tubular subassembly member 40 having a smaller outside circumference 45 through the center of the internal turbulizer subassembly member 70 to expand the turbulizer slightly, and thus mechanically force the corrugated peak apex ridges 92 and the corrugated valley base bottoms 94 of the individual corrugated strip triangular cross section peak apex ridges 92 and valley base bottoms 94 to compress into prestressed contact with the respective peripheries of the first outer concentric thin walled tubular subassembly member 20, and the second inner concentric thin walled tubular subassembly member 40. This compressive force is sufficient to assure metal-to-metal contact for effective heat transfer contact between the first outer concentric thin walled tubular subassembly member 20, and the second inner concentric thin walled tubular subassembly member 40, and the internal turbulizer subassembly member 70. The internal turbulizer subassembly member 70 interconnects the first outer concentric thin walled tubular subassembly member 20, and the second inner concentric thin walled tubular subassembly member 40 to produce a longitudinal fluid flow path adjacent to the second inner concentric thin walled tubular subassembly member 40 having a smaller outside circumference 45, and the opposing adjacent first outer concentric thin walled tubular subassembly member 20. Furthermore, in spiral winding the internal turbulizer subassembly member 70 into a helical configuration around the second inner concentric thin walled tubular subassembly member 40 having a smaller outside circumference 45, in accordance with U.S. Pat. No. 3,197,975 an open spiral gap space 78, is formed providing a series of gapped non-turbulizer sections in the second inner concentric thin walled tubular subassembly member 40, formed between adjacent helical turns of the helical spiraled turbulizer subassembly. There is thus defined an open-gapped helical spiral internal fluid flow turbulizer longitudinal passageways 72, as shown in FIG. 2, into which each longitudinal passageway series has a periodically open spiral gap space 78. The longitudinal passageways are thus interrupted by the spiral gap space 78 periodically by the spiral passageway 76-bridge spiral gap space 78. These minimize spiral gap space 78 resistance to fluid flow through intermediate inner annular flow channel axial region member 60 and provides for the efficient transfer of heat to and from the fluid passing through the intermediate inner annular flow channel axial region member 60, as confined by the respective sidewalls of the first outer concentric thin walled tubular subassembly member 20, and second inner concentric thin walled tubular subassembly member 40
It has been determined that the fluid flow within the intermediate inner annular flow channel axial region member 60 forms a non-circulating skin film of fluid on the turbulizer surfaces at the edges of the internal turbulizer subassembly member 70 that becomes progressively thicker extending towards maximum circulation at the circumference edge of the gapped spiral turbulizer member, and this condition acts as a heat insulator causing resistance to heat transfer and reducing the efficiency of the heat exchanger system. An advantage of the helical internal fin heat exchanger of U.S. Pat. No. 3,197,975 is that the longitudinal dimensions of each of the individual passageway surfaces of the corrugated turbulizer strip subassembly members prevent the formation of a non-circulating fluid flow film sufficient to interfere materially with the proper transfer of heat between portions of the fluid flow traversing longitudinal intermediate inner annular flow channel axial region member 60. A more effective heat exchange process occurs by reducing surface area portions of the exterior metallic fin strips by prestress fabricating the internal turbulizer subassembly member 70, and then inserting it into the intermediate inner annular flow channel axial region member 60 improve the heat exchange properties of the first outer concentric thin walled tubular subassembly member 20, and second inner concentric thin walled tubular subassembly member 40 employing the internal turbulizer subassembly member 70.
In accordance with the present invention the heat exchange fluid causes flow cross mixing by the triangular corrugation longitudinal channel passageways. As mentioned previously, the heat exchanger, width, length, thickness, and the space-gaps between the edges of the helical strip that define the spiral or helical flow path for the fluid flow confined between the first outer concentric thin walled tubular subassembly member 20 and second inner concentric thin walled tubular subassembly member 40, passes across the spiral gap space 78 in the turbulizer longitudinal passageways 72 defined by the corrugated strip triangular cross section 74 can, by design, substantially vary the effect of the tubulizer anchored end connection 79 of the second inner concentric thin walled tubular subassembly member 40 by varying the quantity of fluid flow passing through the second inner concentric thin walled tubular subassembly member 40.
A finned tubular heat exchanger assembly member 10 can thus be constructed by the selective fabrication of the first outer concentric thin walled tubular subassembly member 20, and second inner concentric thin walled tubular subassembly member 40. When the first outer concentric thin walled tubular subassembly member 20, and second inner concentric thin walled tubular subassembly member 40 are assembled together, the second inner concentric thin walled tubular subassembly member 40 is longitudinally positionally centrally within the first outer concentric thin walled tubular subassembly member 20, whereby the first outer concentric thin walled tubular subassembly member 20, and said second inner concentric thin walled tubular subassembly member 40 concentrically define the outer surface circumference and inner and outer circumference of the intermediate inner annular flow channel axial region member 60.
An internal turbulizer subassembly member 70 is embossed in a manner to provide a lateral triangular cross-sectional area to be inserted within the intermediate inner annular flow channel axial region member 60 to produce therein turbulizer longitudinal passageways 72. The thus formed internal turbulizer subassembly member 70 is then end anchored to the second inner concentric thin walled tubular subassembly member 40 to anchor the internal turbulizer subassembly member 70. The internal turbulizer subassembly member 70 is fabricated around the second inner concentric thin walled tubular subassembly member 40 initially with a predetermined compressive force to first contract, and then after insertion, expand to maximize surface contact with the first outer concentric thin walled tubular subassembly member 20, and said second inner concentric thin walled tubular subassembly member 40. The internal turbulizer subassembly member 70, when end anchored to the second inner concentric thin walled tubular subassembly member 40, produces a turbulizer end anchor connection 80 configuration designed to vary the cross-sectional flow area of the internal circumference of the second inner concentric thin walled tubular subassembly member 40 and the intermediate inner annular flow channel axial region member 60.
An anchor end connection slot 82 is machined in the second inner concentric thin walled tubular subassembly member 40 to connect with the anchor end connection tail structure 84.
The anchor end connection tail structure 84 protruding through the thin side walled of the second inner concentric thin walled tubular subassembly member 40 having a smaller outside circumference 45. This turbulizer anchor end connection 79 may limit fluid flow conductance through the second tubular subassembly inner flow channel 27, thereby by its design providing fluid flow control of the finned tubular heat exchanger assembly 10.
One embodiment of the finned tubular heat exchanger assembly member 10 has an internal turbulizer subassembly member 70 positioned in the intermediate inner annular flow channel axial region member 60, and is constructed with a uniform sided, truncated triangular cross-sectional area having a rounded apex cross-section.
The heat exchanger has a helically formed turbulizer that is uniform and sequentially gap interrupted passageway and external fins are formed radially with surface, semi-circular uniform corrugations to improve heat transfer by increasing the external surface area.
The finned heat exchanger assembly in operation combines four walled members comprising a finned exterior, planner member, two concentric tubular members, and a triangular passageway member. The first concentric tubular walled member having a first inner circumference; and a second concentric tubular walled member having a smaller outer circumference than the inner circumference of the first concentric tubular walled member when assembled together, the first concentric tubular walled member is longitudinally centralized positionally within the first concentric tubular walled member to conduct fluid flow through both tubular members. The first concentric tubular walled member and the second concentric tubular walled members concentrically define the outer circumference and inner circumference of an intermediate inner annular fluid flow channel that contains a helically formed, spirally wound turbulizer strip constructed with a lateral triangular cross-sectional configuration surface and is adapted to be inserted into the inner annular fluid flow channel to form therein the longitudinal triangular flow passageway
By anchor fastening the helical formed turbulizer strip, member end connection to the second concentric tubular walled member turbulizer strip member is to positionally stabilize, and the fluid conducting through and around the tubular subassembly may be varied to contain fluid flow, and thereby heat exchanger, heat transfer characteristics.
The four fluid flow conductance paths, including the fluid flow comprising the heat exchanger extends the two concentric tubular fluid, the tubular passageway comprises in combination to provide a versatile heat exchange wherein the heat exchange requirements of a system can be satisfied by the proper pre selected design choice of fluid flow paths and media choice. The surface design of the exterior fins may be corrugated to increase surface area, the tubular member wall there has, internal and external diameters may be varied, the intermediates inner annular fluid flow channel may be varied, and the tubular subassembly may be varied to produce the desired heat exchanger heat transfer results.
While we have shown and described particular embodiments of our invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from our invention in its broader aspects; and we, therefore, intend herein to cover all such changes and modifications as fall within the true spirit and scope of our invention.

Claims

1: A finned heat exchanger assembly formed by the combination of at least two concentric thin walled tubular members comprising:

a. a first outer concentric thin walled tubular member having a larger first inside circumference;

b. a second inner concentric thin walled tubular member having a smaller second outside circumference than said larger first inside circumference of said first outer concentric thin walled tubular member, so that when said tubular members are assembled concentrically together, said first outer concentric thin walled tubular member is longitudinally centered axially within said first concentric thin walled tubular member, and said first outer concentric thin walled tubular member and said second inner concentric thin walled tubular member concentrically define therebetween an intermediate inner annular fluid flow channel being coincidental with a portion of the inner channel of the first outer concentric thin walled tubular member;

c. a helically formed, spirally wound turbulizer strip subassembly being constructed with laterally displaced triangular cross-sectional areas to form therein longitudinal triangular flow passageways and said turbulizer strip subassembly adapted to be inserted into said intermediate inner annular fluid flow channel;

d. said helical formed turbulizer strip subassembly being end connection anchored to the sidewall of said second inner concentric thin walled tubular member to positionally locate and stabilize said turbulizer strip subassembly within said intermediate inner annular fluid flow channel;

e. said turbulizer strip subassembly being assembled initially with a predetermined compressive force to first contract, and then after insertion expand to maximize surface contact with both said first outer concentric thin walled tubular member and said second inner concentric thin walled tubular member positioned within said intermediate inner annular fluid flow channel; and

f. at least one end of said turbulizer strip having an end connection anchored through said second inner concentric thin walled tubular member, and said end connection anchoring being adapted to vary the cross-sectional flow area of said second tubular inner circumferential area and the cross-sectional flow area of said intermediate inner annular fluid flow channel.

2: The heat exchanger, as claimed in claim 1, wherein said spirally helically wound turbulizer strip is constructed of a heat conductive metal strip.

3: The heat exchanger, as claimed in claim 2, wherein said helical spirally wound turbulizer strip is fabricated with a uniform truncated apex area.

4: The heat exchanger, as claimed in claim 3, wherein said helical turbulizer strip is fabricated with a corrugated triangular cross-sectional rounded apex.

5: The heat exchanger, as claimed in claim 4, wherein said turbulizer is formed as a uniform helix.

6: The heat exchanger, as claimed in claim 5, having external thermal corrugated rectangular fins to improve heat transfer.

7: The heat exchanger, as claimed in claim 6, wherein said external thermal fins are formed with radial, semi-circular uniform, contoured corrugations to increase heat surface area.

8: A finned heat exchanger assembly formed by the combination of at least two concentric thin walled tubular members comprising:

b. a second inner concentric thin walled tubular member having a smaller second outside circumference than said larger first inside circumference of said first outer concentric thin walled tubular member, so that when said tubular members are assembled concentrically together, said first outer concentric thin walled tubular member is longitudinally centered axially within said first concentric thin walled tubular member, and said first outer concentric thin walled tubular member and said second inner concentric thin walled tubular member concentrically define therebetween said larger first inside concentric circumference and said smaller second outer circumference an intermediate inner annular fluid flow channel being coincidentally with a portion of the inner channel of the first outer concentric thin walled tubular member;

9: The heat exchanger, as claimed in claim 8, wherein said spirally helically wound turbulizer strip is constructed of a heat conductive metal strip.

10: The heat exchanger, as claimed in claim 9, wherein said helical, and spirally wound turbulizer strip is fabricated with a uniform truncated triangular cross-sectional apex.

11: The heat exchanger, as claimed in claim 10, wherein said helical turbulizer strip is fabricated with a corrugated triangular cross-section having a rounded apex.

12: The heat exchanger, as claimed in claim 11, wherein said turbulizer is formed in a uniform helix.

13: The heat exchanger, as claimed in claim 12, having external thermal fins to improve heat transfer.

14: The heat exchanger, as claimed in claim 13, wherein said external thermal fins are formed with radial, semi-circular uniform surface corrugations to increase heat surface area.

15: A method of fabricating a finned heat exchanger assembly formed by the combination of at least two concentric thin walled tubular members comprising:

a. fabricating a first outer concentric thin walled tubular member having a larger first inside circumference;

b. fabricating a second inner concentric thin walled tubular member having a smaller second outside circumference than said larger first inside circumference of said first outer concentric thin walled tubular member, so that when said tubular members are assembled concentrically together, said first outer concentric thin walled tubular member is longitudinally centered axially within said first concentric thin walled tubular member, and said first outer concentric thin walled tubular member and said second inner concentric thin walled tubular member concentrically define therebetween said larger first inside concentric circumference and said smaller second outer circumference an intermediate inner annular fluid flow channel being partially coincidental with the inner channel of the first outer concentric thin walled tubular member;

c. forming a helical, spirally wound turbulizer strip subassembly with laterally displaced triangular cross-sectional flow areas to form therein longitudinal triangular flow passageways, and said turbulizer strip assembly and adapted to be inserted into said intermediate inner annular fluid flow channel;

d. securely anchoring said helical formed turbulizer strip subassembly to the sidewall of said second inner concentric thin walled tubular member to postionally locate and stabilize said turbulizer strip subassembly within said intermediate inner annular fluid flow channel;

e. said turbulizer strip subassembly being assembled initially with a pre-determined compressive force to first contract, and then after insertion expand to maximize surface contact with both said first outer concentric thin walled tubular member and said second inner concentric thin walled tubular member positioned within said intermediate inner annular fluid flow channel; and

d. at least one end of said turbulizer strip having an end connection anchored to said second inner concentric thin walled tubular member, and said end anchoring connection structure being adapted to vary the cross-sectional flow area of said second tubular inner area of said second inner concentric thin walled tubular member and the cross-sectional flow area of said intermediate inner annular fluid flow channel.

16: The heat exchanger, as claimed in claim 15, wherein said spirally helically wound turbulizer strip is constructed of a heat conductive metal strip.

17: The heat exchanger, as claimed in claim 16, wherein said turbulizer strip is fabricated with a uniform truncated triangular cross-sectional area.

18: The heat exchanger, as claimed in claim 17, wherein said helical turbulizer strip is fabricated with a corrugated triangular cross-section having a rounded apex.

19: The heat exchanger, as claimed in claim 19, having external corrugated thermal fins to improve heat transfer.

20: The heat exchanger, as claimed in claim 20, wherein said external thermal fins are formed with radial, semi-circular uniform corrugations to increase heat surface area.