Reverse flow parallel thermal transfer unit

Abstract

A parallel flow thermal transfer unit is disclosed having high efficiency and a constant gradient along the length of the flow. The thermal transfer unit includes flow control elements within the path of the flow to produce desired flow characteristics.

Description

PRIORITY CLAIM TO RELATED U.S. APPLICATIONS

To the full extent permitted by law, the present non-provisional patent application claims priority to and the benefit of U.S. Provisional patent application Ser. No. 60/864,046, entitled “REVERSE FLOW PARALLEL THERMAL TRANSFER UNIT,” filed on Nov. 2, 2006, which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally to heat exchangers, and more specifically, to a method and apparatus for exchanging heat using countercurrent fluid flow.

2. Description of Related Art

In various processes, it is desirable to increase the efficiency of the process by transferring thermal energy from one process where the thermal energy is not needed to another process that needs to be heated. Such transfers of thermal energy often occur across an exchange medium or barrier, and utilize one or more gases or fluids (generally, “fluid” or “fluids”) as the transfer agents.

One system which has been used to achieve such a result is a concurrent heat exchanger. In a concurrent heat exchanger, two or more process fluids are thermally joined in a parallel flow, such that the temperature differential between the two fluids decreases as the time in which the two fluids are transferring heat increases. In that manner, at the outlet of the heat exchanger, if the two fluids transfer heat for a sufficient period of time, the resulting temperature will be a mean or average of the two incoming inlet fluid temperatures and the heat exchange at or near the outlet will be negligible.

An alternative system is a countercurrent heat exchanger. Countercurrent heat exchangers are used to simultaneously cool an incoming high energy working fluid, i.e. an initially warm fluid, and to warm a lower energy fluid, i.e. an initially cool fluid. The warm fluid and cold fluid flow in opposite directions while in thermal contact with a heat transfer barrier, normally a high thermal conductivity metal, which facilitates the transfer of heat or energy from the warm fluid to the cold fluid while maintaining the physical separation of the two fluids.

Countercurrent heat exchangers are typically the most efficient means by which energy may be transferred from a high energy fluid to a lower energy fluid, because the temperature difference between the two fluids is maintained; thus, maintaining the rate at which heat is exchanged. Additionally, because of the manner in which the two fluids exchange heat, the incoming high energy fluid can be brought to a temperature that approaches the incoming low energy fluid, and vise versa. Thus, heat exchange in a countercurrent heat exchanger occurs throughout the length of the fluid flow in the heat exchanger, provided that there exists a difference in temperature between the high energy and low energy fluid.

Countercurrent heat exchangers of the current art, nonetheless, have several disadvantages. First, the efficiency of the heat exchanger suffers due to energy movement within the structure of the heat exchanger by conduction. This causes a breakdown in the maintenance of the temperature difference between the two fluids, and, thus, causes a reduced efficiency due to fluctuation in the temperature differential. Second, the efficiency of the heat exchanger suffers due to energy loss to the environment. Third, the size and configuration of the flow channels within the heat exchanger contribute to uneven temperature gradients within the fluids and to uneven flow rates within the flow channels due to turbulence.

It is desirable, therefore, to provide a heat exchanger system which improves the efficiency of the heat exchange between process fluids, particularly by controlling energy losses, and both fluid and thermal flow characteristics.

BRIEF SUMMARY OF THE INVENTION

Briefly described, in a preferred embodiment, the present invention overcomes the above-mentioned disadvantages and meets the recognized need for such a device by providing a thermal transfer unit comprising at least one first flow channel having a first interior space, at least one second flow channel having a second interior space, at least one thermal barrier thermally connecting the at least one first flow channel with the at least one second flow channel, a first flow medium disposed within the first interior space, a second flow medium disposed within the second interior space, and a plurality of flow control elements disposed within at least one of the first flow channel and the second flow channel, the plurality of flow control elements creating a predetermined flow pattern.

According to one aspect of the preferred embodiment, the flow control elements create a vortex flow pattern.

According to another aspect of the preferred embodiment, the flow channels comprise a low heat conducting material.

According to another aspect of the preferred embodiment, the thermal transfer unit comprises a thermal insulation material to reduce thermal energy loss to the environment.

According to another aspect of the preferred embodiment, the thermal barrier includes thermally insulating portions which prevent the transfer of thermal energy along the length of the thermal barrier.

According to another aspect, the present invention overcomes the above-mentioned disadvantages and meets the recognized need for such a device by providing a thermal transfer system comprising a first modular thermal transfer unit comprising a first flow channel, a second flow channel, a first thermal barrier thermally connecting said first flow channel to said second flow channel, a first connector connected to an input of said first flow channel, a second connector connected to an output of said first flow channel, a third connector connected to an input of said second flow channel, and a fourth connector connected to an output of said second flow channel, and a second modular thermal transfer unit comprising a third flow channel, a fourth flow channel, a second thermal barrier thermally connecting said third flow channel to said fourth flow channel, a fifth connector connected to an input of said third flow channel, a sixth connector connected to an output of said third flow channel, a seventh connector connected to an input of said fourth flow channel, and an eighth connector connected to an output of said fourth flow channel, wherein said second connector is removably connected to said fifth connector, and said eighth connector is removably connected to said third connector.

These and other objects, features, and advantages of the invention will become more apparent to those ordinarily skilled in the art after reading the following Detailed Description and Claims in light of the accompanying drawing Figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Accordingly, the present invention will be understood best through consideration of, and reference to, the following Figures, viewed in conjunction with the Detailed Description of the Preferred Embodiment referring thereto, in which like reference numbers throughout the various Figures designate like structure and in which:

FIG. 1 is a longitudinal cross-section view of a preferred embodiment of the thermal transfer unit of the present invention;

FIG. 2 is a longitudinal cross-section view of an alternative embodiment of the thermal transfer unit of the present invention;

FIG. 3 is a side view of the thermal transfer unit of the present invention;

FIG. 4 is a transverse cross-section view of the thermal transfer unit of the present invention;

FIG. 5 is an exploded perspective view of the thermal transfer unit of the present invention;

FIG. 6 is a perspective view of modular sections comprising the thermal transfer unit according to a preferred embodiment of the present invention;

FIG. 7 is an end view of the thermal transfer unit according to the embodiment of FIG. 6;

FIG. 8 is a transverse cross-section view of the thermal transfer unit according to a preferred embodiment illustrating vortexes in a working fluid;

FIG. 9 is a perspective view of an alternative flow pattern of a working fluid in the thermal transfer unit;

FIG. 10 is a perspective view of flow control elements on thermal barriers of the thermal transfer unit;

FIG. 11 is a longitudinal cross-section view of the thermal transfer unit according to an alternative embodiment;

FIG. 12 is an exploded view of a connector for use with the thermal transfer unit according to the embodiment of FIG. 11; and,

FIG. 13 is a transverse cross-section view of the thermal transfer unit according to the embodiment of FIG. 11, illustrating vortexes in a working fluid.

It is to be noted that the drawings presented are intended solely for the purpose of illustration and that they are, therefore, neither desired nor intended to limit the invention to any or all of the exact details of construction shown, except insofar as they may be deemed essential to the claimed invention.

DETAILED DESCRIPTION OF THE INVENTION

In describing preferred embodiments of the present invention illustrated in the Figures, specific terminology is employed for the sake of clarity. The invention, however, is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner to accomplish a similar purpose.

It will also be understood that the present invention is intended for function, use, and application to heat transfers within and between gases, liquids, gaseous media, fluids, fluidized media, combined gaseous and/or fluid media, and combinations thereof. Accordingly, any reference herein to a fluid should be understood to include reference to gases, liquids, gaseous media, fluids, fluidized media, combined gaseous and/or fluid media, and combinations thereof.

In that form of the preferred embodiment of the present invention chosen for purposes of illustration, FIG. 1 shows a cross-sectional view of thermal transfer unit 100 according to the present invention. Thermal transfer unit 100 is shown in a serpentine configuration in order to reduce the overall size of the unit. Thermal transfer unit 100 comprises a plurality of layers 101, 102, 103, 104, 105, 106, and 107. Thermal transfer unit 100 has a length dimension that follows the serpentine configuration from first end 100a to second end 100b, a thickness dimension in the direction from layer 101 to layer 107, and a width dimension orthogonal to both the length dimension and the thickness dimension.

Layers 101 and 107 are the bottom and top layer, respectively, of the main body of thermal transfer unit 100, and are preferably made of thermally insulating material. Layers 102, 104, and 106 comprise flow channels that carry a low thermal energy flow medium from first end 100a to second end 100b along the length of each layer. The low thermal energy flow medium can be a process fluid that requires heating, or can be a waste fluid that can absorb thermal energy. Layers 103 and 105 comprise flow channels that carry a high thermal energy flow medium from second end 100b to first end 100a. The high thermal energy flow medium can be a process fluid that requires cooling, or can be a waste fluid from which thermal energy can be extracted.

Between each of layers 102 through 106 is a thermal barrier 110. Each thermal barrier 110 preferably comprises a high thermal conductivity material that thermally connects the flow media in adjacent flow channels, and is preferably no thicker than is necessary for structural integrity given desired configuration and an intended application, including process pressures thereof and longevity requirements. In a preferred embodiment, each thermal barrier 110 comprises thermally insulating portions disposed along the length of thermal transfer unit 100 from first end 100a to second end 100b. The thermally insulating portions prevent the transfer of thermal energy within the thermal barrier 110 along the length of the thermal barrier 110.

Also shown in FIG. 1 are thermal insulating layers 111, disposed between layers 101 and 107 of the interior layers of the thermal transfer unit 100. The thermal insulating layers 111 prevent unwanted transfer of thermal energy between the adjacent flow medium and layers 101 and 107 of the main body of thermal transfer unit 100. Additionally, exterior insulation and/or heat reflective films may be added to exterior portions of thermal transfer unit 100 to further reduce transfer of thermal energy to an outside environment. Additionally, thermal transfer unit 100 may optionally be stored in a vacuum to reduce thermal transfer to the outside environment. Additionally, the configuration, serpentine or other, of thermal transfer unit 100 is preferably selected such that potions of thermal transfer unit 100 carrying flow media of similar temperatures are disposed near one another so as to reduce the temperature differential between adjacent or proximate portions of thermal transfer unit 100.

Referring again to layers 102 and 106, as is best shown in the inset drawings, outer layers 102 and 106 have a depth in the thickness direction that is less than the depth in the thickness direction of inner layers 103, 104, and 105. Preferably the depth of outer layers 102 and 106 is half of the depth of inner layers 103, 104, and 105. The smaller depth dimension of layers 102 and 106 serves to equalize the volume of fluid in thermal contact with each thermal barrier so that the transfer of thermal energy from the high thermal energy fluid medium to the low thermal energy fluid medium is consistent between all the layers at a given length along thermal transfer unit 100. Additionally, if the fluid medium in one flow channel has a thermal capacity different than the thermal capacity of the fluid medium in an adjacent flow channel, the depth in the thickness direction of the respective flow channels is preferably configured such that the thermal capacities of the respective flow channels are equal, or nearly equal.

FIG. 2 shows an alternative embodiment of thermal transfer unit 100, which is in most respects identical to the embodiment of FIG. 1. The main difference is illustrated in the inset drawing. As shown in FIG. 2, the alternative embodiment has layers 103 and 105 open to the back side and closed to the front side at first end 100a of thermal transfer unit 100 by two flow diverters 120, and has layers 102, 104, and 106 open to the front side and closed to the back side at first end 100a of thermal transfer unit 100 by three additional flow diverters (not shown). By contrast, the embodiment of FIG. 1 has an opposite configuration with layers 103 and 105 open to the front side and closed to the back side at first end 100a of thermal transfer unit 100 by two flow diverters (not shown), and with layers 103, 104, and 106 open to the back side and closed to the front side at first end 100a of thermal transfer unit 100 by three flow diverters 120.

FIG. 3 shows the embodiment of FIG. 1 from the front side. From this view, port 130 can be seen at each of first end 100a and second end 100b. Each port 130 comprises an opening in the front side layer 108 of the main body of the thermal transfer unit 100. Ports 130 work in conjunction with flow diverters 120 to make each of layers 102 through 106 selectively open or closed to the port.

Referring now to FIG. 4, a transverse cross-sectional view of thermal transfer unit 100 is shown. Main body bottom layer 101, main body top layer 107, main body front side layer 108, and main body back side 109 are shown as comprising two unitary halves of the main body of thermal transfer unit 100: upper half 100c and lower half 100d. Also shown are thermal insulating layers 111 disposed on front side layer 108 and back side layer 109.

Flow control elements 140 can be seen projecting from both the upper and lower surface of each thermal barrier 110. Without flow control elements 140, the fluid medium flowing through the flow channels defined by layers 102 through 106 would be characterized by turbulence due to the shape and the size of the layer and by the interaction of the fluid medium with the interior surfaces of the flow channel. Such turbulence can cause uneven flow speeds and an uneven distribution of thermal energy within the flow medium along the length of the flow channel. Flow control elements 140 are designed to reduce the effects of turbulence on the efficiency of the thermal transfer unit by reducing turbulence and creating a predetermined flow pattern, such as a vortex. The vortex flow pattern is particularly beneficial because in addition to creating even flow within the flow channel, the vortex flow pattern effectively increases the length of the flow channel for a given set or exterior dimensions. The result is that the fluid medium spends more time within the flow channel and comes into contact with more surface area of thermal barrier 110, increasing the amount of thermal energy transferred to or from the other fluid medium through thermal barrier 110.

In use, a vortex flow pattern causes movement of the fluid medium from a region proximate to the surface of the thermal barrier to a central region of the flow channel. This causes removal of fluid medium that has a temperature close to the average temperature of the thermal barrier from regions nearby the thermal barrier, and causes fluid medium that has a temperature closer to the average temperature of the fluid medium in areas at the same length along the thermal transfer unit to move into the regions nearby the thermal barrier.

FIG. 5 shows an exploded view of the first end 100a of thermal transfer unit 100 according to the embodiment of FIG. 1. The main body of thermal transfer unit 100 is shown including two pieces comprised of layers 101, 107, 108, and 109. When combined, openings in each of the two pieces form front side port 130 and back side port 130. Also shown is thermal insulator 111, also formed in two pieces, which lines the interior surfaces of each piece of the main body. First flow diverter 120 is disposed adjacent the bottom of thermal insulator 111 and is shaped such that a side surface extends completely over front port 130; thereby, closing off the front port 130 from layer 102. The other side of flow diverter 120 is tapered along its length to allow fluid medium flowing in the flow channel of layer 102 to flow into or out of the flow channel through back port 130. Thermal barrier 110 is disposed on top of flow diverter 120 and encloses the flow channel of layer 102.

Another flow diverter 120 is disposed on top of thermal barrier 110 enclosing layer 102 and has a tapered front side, opening the flow channel of layer 103 to front port 130, and an elongated back side closing the flow channel of layer 103 from back port 130. Another thermal barrier 110 is disposed on top of this flow diverter 120 and encloses the flow channel of layer 103. In this way, each subsequent layer of thermal transfer unit 100 includes a flow diverter 120 of alternating configuration.

Also shown in FIG. 5 are portions 111a of thermal insulator 111 that protrude from the openings in the main body that comprise front and back ports 130. Portions 111a can optionally serve as connectors to which fluid conduits can be attached to distribute the fluid media as required by the application process.

Now referring to FIG. 6, thermal transfer system 600 is shown comprising a plurality of modular sections 600a, 600b, 600c, 600d, and 600e. Each of the plurality of modular sections comprises an individual thermal transfer unit 100. As shown in FIG. 6, each thermal transfer unit 100 is U-shaped, although alternative configurations, such as the serpentine configuration of FIG. 1 are contemplated. Connectors 610 are connected to each of the front and back side ports of ends 100a and 100b of each thermal transfer unit 100 making up the thermal transfer system 600. Connectors 610 can also be interconnected as shown in FIG. 6 such that flow channels in each of the modular sections are connected to form a single flow channel from a first end of a first modular section to a second end of the last modular section.

FIG. 7 shows the thermal transfer system 600 from an end view, and further shows how the front side ports of the first and second end are connected to respective front side ports of adjacent modular sections. For example, front side port of the second end of modular section 600b, designated O₁ is connected to front side port of the first end of modular section 600c, designated I₁, and the back side port of the first end of modular section 600c, designated O₂ is connected to the back side port of the second end of modular section 600b, designated I₂.

Now referring to FIG. 8, a transverse cross-sectional view of thermal transfer unit 800 of FIG. 4 is shown. FIG. 8 includes arrows that indicate the direction of flow of the fluid medium created by flow control elements 840. As shown, the flow pattern created by flow control elements 840 is a plurality of vortexes. Flow control elements 840 can be discrete projections or fins, or can be continuous along the length of the thermal transfer unit 800. Preferably, flow control elements 840 comprise fins that are thermally connected to the thermal barriers 810 and comprise a similar thermally conductive material; thereby, effectively increasing the surface area of thermal barrier 810 over which thermal energy can be gathered or dissipated.

FIG. 9 shows a perspective view of an alternative flow pattern of the fluid medium caused by flow control elements 840. In this alternative flow pattern, adjacent vortexes have opposing rotation, such that turbulence at the edges of adjacent vortexes is reduced by eliminating opposing directions of flow at adjacent portions.

FIG. 10 shows a perspective view of flow control elements 840 on thermal barriers 810 that produce the flow pattern of FIG. 9.

Now referring to FIG. 11, an alternative configuration of thermal transfer unit 1100 is shown. According to the alternative embodiment, thermal transfer unit 1100 comprises a plurality of tubes arranged in a serpentine configuration. Outer tube 1101 serves as the body for thermal transfer unit 1101, and comprises a thermally insulating material. First flow tube 1102 is disposed proximate an interior surface of outer tube 1101. Second flow tube 1103 is disposed centrally within first flow tube 1102 and spaced from an interior surface thereof; thereby, defining first flow channel 1104. Second flow tube 1103 is hollow and defines second flow channel 1105. Additionally, solid displacement tube 1106 may optionally be disposed centrally within second flow tube 1103 and can be held in place at the center of the second flow tube 1103 by spacers. The inclusion of solid displacement tube 1106 serves to reduce the volume of second flow tube 1103 while maintaining the larger surface area of second flow tube 1103.

In the embodiment of FIG. 11, second flow tube 1103 serves as the thermal barrier and is made of a high thermal conductivity material in order to facilitate the transfer of thermal energy to or from a first fluid medium disposed in first flow channel 1104, to or from a second fluid medium disposed in second flow channel 1105.

First flow tube 1102 has an input and an output connection that comprises an extension of first flow tube 1102 that projects from each end of thermal transfer unit 1100 and is offset from the center of the plurality of tubes. Second flow tube 1103 likewise has an input and an output at each end of thermal transfer unit 1100.

As shown in FIG. 12, connector 1200 can be used to facilitate connection of first flow channel 1104 and second flow channel 1105 to process flow conduits. Connector 1200 comprises a molded adapter that includes offset connection portion 1201 for connecting to first flow channel 1104 and central connection portion 1202 for connecting to second flow channel 1105. Inner sleeve 1203 attaches to an interior of connection portion 1202 at a first end, and attaches to second flow tube 1103 at a second end, forming a sealed flow channel from connection portion 1202 to second flow channel 1105. Outer sleeve 1204 attaches to connection portion 1201 at a first end, and attaches to first flow tube 1102 at a second end, forming a sealed flow channel from connection portion 1201 to first flow channel 1104.

Now referring to FIG. 13, a cross-sectional view of thermal transfer unit 1200 is shown. Flow control elements 1240 are disposed on the interior surface of first flow tube 1102, interior and exterior surfaces of second flow tube 1103, and the exterior surface of solid displacement tube 1106. The flow control elements create vortexes represented by arrows indicating the motion of the fluid medium flowing through first flow channel 1104 and second flow channel 1105. Also shown are spacers 1160 that maintain second flow tube 1103 and solid displacement tube 1106 at the desired spacing. Optionally, spacers 1160 may be arranged such that they do not interfere with the creation of a desired flow control pattern, and may optionally be configured to aid in such creation.

The use of flow control devices to regulate a rate of flow through one or more flow channels is contemplated in order to ensure a desired flow rate prevails in the flow channel such that equalized thermal capacity between adjacent flow control channels is maintained.

Having, thus, described exemplary embodiments of the present invention, it should be noted by those skilled in the art that the within disclosures are exemplary only and that various other alternatives, adaptations, and modifications may be made within the scope and spirit of the present invention. Accordingly, the present invention is not limited to the specific embodiments as illustrated herein, but is only limited by the following claims.

Claims

1. A thermal transfer unit comprising:

at least one first flow channel having a first interior space;

at least one second flow channel having a second interior space;

at least one thermal barrier thermally connecting said at least one first flow channel with said at least one second flow channel;

a first flow medium disposed within said first interior space;

a second flow medium disposed within said second interior space; and

a plurality of flow control elements disposed within at least one of said first flow channel and said second flow channel, said plurality of flow control elements creating a predetermined flow pattern.

2. The thermal transfer unit of claim 1 wherein said predetermined flow pattern is at least one vortex.

3. The thermal transfer unit of claim 1 wherein said plurality of flow control elements comprises a plurality of fins projecting into at least one of said first interior space and said second interior space.

4. The thermal transfer unit of claim 1 wherein said first flow medium flows in a first direction, and said second flow medium flows in a second direction, the second direction being opposite, and parallel to the first direction at least in portions where said first flow medium is in thermal contact with said second flow medium.

5. The thermal transfer unit of claim 1 wherein said at least one first flow channel comprises a rectangular cross-section, said at least one second flow channel comprises a second flow channel and a third flow channel, said second flow channel disposed on a first side of said first flow channel and said third flow channel disposed on an opposite side of said first flow channel.

6. The thermal transfer unit of claim 5 wherein a depth of said second flow channel and a depth of said third flow channel is approximately half of a depth of said first flow channel, where said depths are in a direction from said second flow channel to said third flow channel;

7. The thermal transfer unit of claim 5 wherein said first flow medium flows in a first direction, and said second flow medium flows in a second direction, said second direction being opposite and parallel to said first direction at least in portions where said first flow medium is in thermal contact with said second flow medium.

8. The thermal transfer unit of claim 1 wherein said at least one first flow channel comprises a circular cross-section, and said second flow channel comprises a circular cross section and encompasses said first flow channel.

9. The thermal transfer unit of claim 8 wherein said first flow medium flows in a first direction, and said second flow medium flows in a second direction, said second direction being opposite and parallel to said first direction at least in portions where said first flow medium is in thermal contact with said second flow medium.

10. The thermal transfer unit of claim 1 wherein at least one of said at least one first flow channel, said at least one second flow channel comprises a low heat conductive material.

11. The thermal transfer unit of claim 1 further comprising a thermal insulating material disposed on an outer surface of said thermal transfer unit to reduce transmission of thermal energy to an environment surrounding said thermal transfer unit.

12. The thermal transfer unit of claim 1 wherein said thermal barrier comprises thermal insulating portions to reduce transmission of thermal energy in direction orthogonal to a direction from said at least one first flow channel to said at least one second flow channel.

13. The thermal transfer unit of claim 1 wherein said at least one first flow channel comprises n first flow channels of equal cross-sectional dimensions, where n is an integer, and said at least one second flow channels comprises n+1 second flow channels, said n+1 second flow channels arranged in an alternating layer configuration with said n first flow channels, wherein each of the outermost second flow channels has a reduced thickness, and each of the other second flow channels has cross-sectional dimensions equal to said first flow channels.

14. The thermal transfer unit of claim 1 wherein each of said at least one first flow channel and said at least one second flow channel comprises at least one input connector and at least one output connector, wherein said output connector is connectable to an input connector of a second thermal transfer unit, thereby increasing a total length of said at least one first flow channel and said at least one second flow channel.

15. A thermal transfer system comprising:

a first modular thermal transfer unit comprising a first flow channel, a second flow channel, a first thermal barrier thermally connecting said first flow channel to said second flow channel, a first connector connected to an input of said first flow channel, a second connector connected to an output of said first flow channel, a third connector connected to an input of said second flow channel, and a fourth connector connected to an output of said second flow channel; and

a second modular thermal transfer unit comprising a third flow channel, a fourth flow channel, a second thermal barrier thermally connecting said third flow channel to said fourth flow channel, a fifth connector connected to an input of said third flow channel, a sixth connector connected to an output of said third flow channel, a seventh connector connected to an input of said fourth flow channel, and an eighth connector connected to an output of said fourth flow channel;

wherein said second connector is removably connected to said fifth connector, and said eighth connector is removably connected to said third connector.

16. The thermal transfer system of claim 15 wherein at least one of said first flow channel, said second flow channel, said third flow channel, and said fourth flow channel comprises a plurality of flow control elements that produce a vortex in a flow medium.

17. The thermal transfer system of claim 15 further comprising a first flow medium disposed in said first flow channel and said second flow channel, and a second flow medium disposed in said second flow channel and said fourth flow channel, wherein said first flow medium flows in a first direction and said second flow medium flows in a second direction opposite and parallel to said first direction.

18. The thermal transfer system of claim 15 wherein at least one of the first flow channel, the second flow channel, the third flow channel, and the fourth flow channel comprises a low heat conducting material.

19. The thermal transfer system of claim 15 further comprising a thermal insulating material disposed on an outer surface of said thermal transfer system to reduce transmission of thermal energy to an environment surrounding said thermal transfer unit.

20. The thermal transfer system of claim 15 wherein at least one of said first thermal barrier and said second thermal barrier comprises thermal insulating portions to reduce transmission of thermal energy in a length direction of said first flow channel, said second flow channel, said third flow channel, or said fourth flow channel.