Patent Publication Number: US-6907739-B2

Title: Thermoelectric heat exchanger

Description:
This application is a continuation of U.S. patent application Ser. No. 09/971,539, filed Oct. 2, 2001 now U.S. Pat. No. 6,606,866 , which is a continuation-in-part of U.S. patent application Ser. No. 09/847,856 filed May 1, 2001 which is a continuation of U.S. patent application Ser. No. 09/428,018 (now U.S. Pat. No. 6,223,539), filed Oct. 27, 1999 which is a continuation of U.S. patent application Ser. No. 09/076,518 (now U.S. Pat. No. 6,119,463), filed May 12, 1998. The entire contents of each of the above-mentioned patents and patent applications is hereby incorporated by reference herein and made a part of this specification. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to temperature control devices. More particularly, the present invention relates to a thermoelectric heat exchanger that is particularly useful for converting electricity to a flow of conditioned air. The air may be heated or cooled. 
   2. Description of the Related Art 
   Modern automobile seats may be equipped with temperature control systems that allow the occupant to vary the temperature of the seat by flowing temperature-controlled air through the seat covering. One type of system comprises a seat having a heat transfer system mounted therein, such as a thermoelectric element configured to heat or cool air that is moved over the element using a separate fan unit that is also mounted within the seat. The conditioned air is distributed to the occupant by passing the air through the seat surface via a series of air ducts within the seat. 
   The amount of space available within, below and around the seat for such temperature control systems is severely limited. In some cars, to save weight or increase passenger room, the seats are a few inches thick and abut the adjacent structure of the car, such as the floorboard or the back of the car. Further, automobile manufacturers are increasingly mounting various devices, such as electronic components or variable lumbar supports, within, below and around the seat. Additionally, the size of the seat, particularly the seat back, needs to be as small as possible to reduce the amount of cabin space consumed by the seat. 
   Present temperature control systems are often too large to be mounted within, below or around vehicle seats. Conventional systems may have a squirrel cage fan five or six inches in diameter generating an air flow that passes through a duct to reach a heat exchanger that adjusts the temperature of the air. The heat exchanger is several inches wide and long, and at least an inch or so thick. From the heat exchanger the air is transported through ducts to the bottom of the seat cushion and to the back of the seat cushion. Such systems are bulky and difficult to fit underneath or inside car seats. Using thermoelectric devices to heat and cool the heat exchanger helps reduce the size of unit, but still requires a large volume for the combined heating and cooling system. 
   The ducting used with these systems is also bulky and difficult to use if the duct must go from a seat bottom to a seat back that is allowed to pivot or rotate. These ducts not only use additional space within the seat, but also resist air flow and thus require a larger fan to provide the air flow, and the larger fan requires additional space or else runs at greater speeds and generates more noise. Noise is undesirable inside motor vehicles. Further, the ducting affects the temperature of the passing air and either heats cool air, or cools heated air, with the result of often requiring larger fans or heat exchangers. In light of these drawbacks, there is a need for a more compact and energy efficient heating and cooling system for automobile seats, and preferably a quieter system. In addition, a more compact and energy-efficient heating and cooling system useful in seats also has uses in other localized conditioned air settings. 
   SUMMARY OF THE INVENTION 
   The present devices use air flow generators, such as fan blades, that act as both a heat exchanger to transfer a thermal differential from a thermoelectric device and thereby condition air passing over the heat exchanger, and that act as an air pump. The heat exchanger rotates and provides aerodynamic and centrifugal force to the air passing through the heat exchanger to generate pressurized air for distribution, such as to the seat of a motor vehicle. 
   An improved thermoelectric heat exchanger system is disclosed. The heat exchanger system has a first heat exchanger formed about an axis and configured such that fluid flows along the first heat exchanger at least partially in a first direction, and a second heat exchanger formed about the axis and configured such that fluid flows along the second heat exchanger at least partially in a direction other than the first direction. A thermoelectric device having opposing surfaces exhibits a temperature gradient between one surface and an opposing surface in response to electrical current flowing through the thermoelectric device. The one surface is in thermal communication with the first heat exchanger and the opposing surface is in thermal communication with the second heat exchanger. 
   Several different combinations of fluid flow directions are disclosed. For example: the first direction is at least partially outward from the axis; the first direction is at least partially perpendicular to the axis; the second direction is at least partially along the axis, while the first direction is generally outward or away from the axis; the first direction is at least partially at an angle from the axis, and the second direction is at least partially at an angle from the axis; the first direction is at least partially along the axis, and the second direction is at least partially at an angle from the axis. 
   In one embodiment, a heat transfer member is in thermal communication with the one or the opposing surface of the thermoelectric device and in thermal communication with the first or second heat exchanger. Another heat transfer member may also be provided in thermal communication with the other surface and with the other heat exchanger. 
   At least one of the first and second heat exchangers may be formed in segments to provide thermal isolation in the direction of flow. The heat transfer members may also be formed in segments to provide thermal isolation in the direction of flow, where one or more heat transfer members are used. Where the heat exchanger is made from a plurality of blades, thermal isolation may be provided by spaces in the blades in the direction of flow. 
   A housing containing at least one of the first and the second heat exchangers may be use to form an outlet through which air exits after passing through the at least one of the first or second heat exchangers. An auxiliary fan may also be used in conjunction with the heat exchangers. In certain configurations, the heat exchangers themselves generate fluid flow. These configurations may also use the auxiliary fan to augment the flow. The auxiliary fan may also be used as the primary or only fluid flow generator. 
   A thermoelectric heat exchanger system is also disclosed that has a thermoelectric device configured to generate a thermal gradient between a first temperature side and a second temperature side in response to an electrical current with at least one first heat exchanger in thermal communication with the first or the second temperature side of the thermoelectric device, wherein the heat exchanger is rotatable about a rotational axis. In this embodiment, an auxiliary fan is configured to rotate about the rotational axis and to generate fluid flow along the heat exchanger. In one embodiment, the first heat exchanger may be oriented such that fluid flow from the auxiliary fan flows through the heat exchanger along the rotational axis. 
   A second heat exchanger may also be provided configured to generate a fluid flow in a first direction away from the rotational axis with rotation about the rotational axis. In such case, the first heat exchanger is preferably oriented such that fluid flow generated by the auxiliary fan flows through the first heat exchanger in a second direction other than the first direction. Advantageously, the heat exchanger is constructed to provide thermal isolation in the direction of flow, such as with segments in blades or the like. 
   Another heat exchanger system is disclosed wherein a thermoelectric device formed about an axis and has opposing surfaces that generate a temperature gradient between one surface and an opposing surface in response to electrical current flowing through the thermoelectric device. In this heat exchanger system, first and second heat exchangers are formed about the axis and configured such that fluid flows along the first heat exchanger and along the second heat exchanger generally away from the axis. The first heat exchanger is in thermal communication with the one surface, and the second heat exchanger is in thermal communication with the opposing surface. At least one of the first and second heat exchangers is formed to provide thermal isolation in the direction of fluid flow between a plurality of portions of the at least one heat exchanger. 
   This configuration can be constructed such that the heat exchangers and thermoelectric device rotate about the axis during operation, at least one of the heat exchangers operating to induce fluid flow through the heat exchangers. Alternatively, the heat exchangers and thermoelectric device are stationary, but an auxiliary fan rotates about the axis and causes fluid to flow along at least one of the first and second heat exchangers. In one preferred embodiment of this system, at least one of the first and second heat exchangers is formed in segments to provide the thermal isolation. 
   Yet another thermoelectric heat exchanger system is disclosed with a thermoelectric device formed about an axis and having opposing surfaces that generate a temperature gradient between one surface and an opposing surface in response to electrical current flowing through the thermoelectric device. First and second heat exchangers are about the axis and configured such that fluid flows along the first heat exchanger and along the second heat exchanger generally away from the axis. The first heat exchanger is in thermal communication with the one surface, and the second heat exchanger is in thermal communication with the opposing surface. An auxiliary fan rotates about the axis and generates fluid flow along at least one of the first and second heat exchangers. Preferably, at least one of the first and second heat exchangers is formed to provide the thermal isolation in the direction of flow, such as through construction in a plurality of substantially thermally isolated segments. 
   A method of conditioning a fluid flow is also contemplated which involves the steps of flowing current through a thermoelectric device having opposing surfaces to generate a temperature gradient between a first surface and a second surface of the thermoelectric device, flowing a fluid along a first heat exchanger formed about an axis at least partially in a first direction, the first heat exchanger in thermal communication with the first surface, and flowing a fluid along a second heat exchanger formed about the axis at least partially in a direction other than the first direction, the second heat exchanger in thermal communication with the second surface. 
   The direction may be in any reasonable configuration, such as, but not limited to: the first direction is at least partially outward from the axis; the first direction is at least partially perpendicular to the axis; the second direction is at least partially along the axis; the first direction is at least partially at an angle from the axis, and the second direction is at least partially at an angle from the axis and; the first direction is at least partially along the axis, and the second direction is at least partially at an angle from the axis. 
   Advantageously, the method further involves forming at least one of the first and second heat exchangers to provide thermal isolation in the direction of flow, such as forming the heat exchangers in segments. The flowing of fluid may be provided by an auxiliary fan that rotates about the axis. In addition, or alternatively, the flowing of fluid may be provided by the first or second heat exchanger rotating about the axis. 
   Yet another method is disclosed, involving the steps of flowing current through a thermoelectric device having opposing surfaces to generate a temperature gradient between a first surface and a second surface of the thermoelectric device, flowing a fluid along a first heat exchanger formed and rotational about an axis, the first heat exchanger in thermal communication with the first surface. The flowing is at least partially provided via an auxiliary fan configured to rotate about the axis and to generate fluid flow along the first heat exchanger. In one embodiment, the first heat exchanger is oriented such that fluid from the auxiliary fan flows through the heat exchanger along the rotational axis. Generating fluid flow along a second heat exchanger in a direction away from the rotational axis with rotation about the rotational axis may also be provided. The second heat exchanger may at least partially generate the fluid flow along the second heat exchanger. The method may also involve thermally isolating portions or segments of the heat exchanger in the direction of fluid flow. 
   Another method of conditioning flowing fluid involves the steps of generating a temperature gradient in a thermoelectric device between one surface and an opposing surface and flowing fluid along first and second heat exchangers formed about an axis and configured such that the fluid flows along the first heat exchanger and along the second heat exchanger generally away from the axis, the first heat exchanger in thermal communication with the one surface, and the second heat exchanger in thermal communication with the opposing surface. At least one of the first and second heat exchangers is formed to provide thermal isolation in the direction of fluid flow, such as by using a plurality of segments to form the at least one heat exchanger. 
   The method may further involve rotating the heat exchangers and thermoelectric device about the axis during operation, the heat exchangers operating to induce fluid flow through the heat exchangers. The heat exchangers and thermoelectric device may also be stationary, wherein fluid flow is generated along at least one of the first and second heat exchangers by rotating an auxiliary fan about the axis. 
   These and other features are disclosed in further detail below. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features of the inventions will now be described with reference to the drawings of an embodiment in which like number indicate like parts throughout, and which are intended to illustrate and not to limit the inventions, and in which: 
       FIG. 1  is a perspective view of the heat exchanger of the present invention; 
       FIG. 2  is a perspective view of a rotary assembly of the heat exchanger of  FIG. 1 ; 
       FIG. 3  is a cross-sectional view of the heat exchanger along line  3 — 3  of  FIG. 1 ; 
       FIG. 4  is an enlarged cross-sectional view of a portion of the heat exchanger; 
       FIG. 5  is a top view of a rotor used with the heat exchanger; 
       FIG. 6  is a side view of the rotor of  FIG. 4 ; 
       FIG. 7  is a schematic view of a seat temperature control system incorporating the heat exchanger of the present invention; 
       FIG. 8  is a perspective view of a cooler box that incorporates the heat exchanger; 
       FIG. 9  is a cross-sectional side view of a lid of the cooler box of  FIG. 8 ; 
       FIG. 10  is a side view of a fan unit incorporating the heat exchanger of the present invention; 
       FIG. 11  is a side cross-sectional view of the fan unit of  FIG. 10 ; 
       FIG. 12  is a perspective view of another embodiment of the heat exchanger; 
       FIG. 13  illustrates an embodiment of a rotary thermoelectric heat exchanger; 
       FIG. 14  depicts the embodiment of a rotary thermoelectric heat exchanger of  FIG. 13  in a housing; 
       FIG. 15  depicts one portion of the rotary thermoelectric heat exchanger in the housing; 
       FIG. 16  depicts a cutaway of another embodiment of a rotary thermoelectric heat exchanger; 
       FIG. 17  depicts a cross-section of a portion of a thermoelectric heat exchanger; and 
       FIG. 18  depicts a portion of a thermoelectric heat exchanger, in which the heat exchangers are generally pancake-shaped, are stationary and attached to an insulator. 
   

   DETAILED DESCRIPTION 
   A variety of examples described below illustrate various configurations that may be employed to achieve desired improvements. The particular embodiments and examples are only illustrative and not intended in any way to restrict the general inventions presented and the various aspects and features of these inventions. In addition, it should be understood that the terms cooling side, heating side, cold side, hot side, cooler side and hotter side and the like do not indicate any particular temperature, but are relative terms. For examples, the “hot,” “heating” or “hotter” side of a thermoelectric element or array may be at ambient temperature, with the “cold,” “cooling” or “cooler” side at a cooler temperature than ambient. Conversely, the “cold,” “cooling” or “cooler” side may be at ambient with the “hot,” “heating” or “hotter” side at a higher temperature than ambient. Thus, the terms are relative to each other to indicate that one side of the thermoelectric is at a higher or lower temperature than the counter-designed side. In addition, fluid flow is referenced in the discussion below as having directions. When such references are made, they generally refer to the direction as depicted in the two dimensional figures. For example, fluid flow for the heat exchanger depicted in  FIG. 13  may be described as away from or along an axis about which these heat exchangers are formed. However, it will be understood from the discussion that the flow when the device is rotating is not just away from the axis or along the axis but may actually take the form of a spiral or have a circular motion or other turbulent flow patterns. The terminology indicating “away” from the axis or “along” the axis or any other fluid flow direction described in the application is meant to be an illustrative generalization of the direction of flow as considered from the perspective of two dimensional figures. 
   As shown in  FIG. 1 , a heat exchanger unit  28  includes an outer housing  32  that defines an interior cavity  29  ( FIG. 3 ) in which a rotor assembly  30  ( FIGS. 2 and 3 ) is rotatably mounted for producing a conditioned airflow into and out of the outer housing  32 . While other shapes are suitable, the outer housing  32  is shown as resembling a generally flat disc with a first surface or first wall  31  that corresponds to an upper or top surface if the housing  32  is placed in a seat bottom generally parallel to the ground. As used herein, up or upper will refer to a direction away from the ground. Down, lower or bottom will refer to a direction toward the ground. The relative direction of parts would alter if the entire orientation of housing  32  were changed, as may occur in actual use. A second wall  33 , corresponding to a bottom surface, is opposite the first wall  31 . The generally circular peripheries of walls  31 ,  33  are joined by side wall  35  to form an enclosure. 
   A first outlet  34  extends outwardly from the side wall  35  adjacent the first or upper wall  31  of the outer housing  32 . A second outlet  36  extends outwardly from the side wall  35  adjacent the second, or lower wall  33 . Advantageously the outlets  34 ,  36  extend generally tangential from the periphery of the housing  32 . The outlets  34 ,  36  are shown extending in generally opposite directions, about 180° relative to each other. But depending on the particular direction the air needs to flow, the outlets  34 ,  36  could be located at other angles relative to each other, with 60°, 90° on either side of the housing  32 , being the most likely relative positions. The outlets  34 ,  36  could exit in the same direction if desired, but then it would be advantageous to have insulation between the outlets to help maintain the temperature differential between the outlets. 
   A set of apertures  38  are centrally formed in the first or top wall  31  of the outer housing  32  to form a first inlet  38  that communicates with the interior cavity  29  formed and enclosed by the outer housing  32 . Although not necessary, a second inlet  40  ( FIG. 3 ) may also be located on the second or bottom wall  33  of the outer housing  32  opposite the first inlet  38 . 
   As illustrated in  FIGS. 2 and 3 , the rotor assembly  30  generally comprises a plurality of components including an annular first rotor  42 , an annular second rotor  44  disposed below the first rotor  42 , and at least one annular thermoelectric device  46  interposed between, and in thermal communication with, the first rotor  42  and the second rotor  44 . The thermoelectric device depicted is preferably a Peltier device which comprises at least one pair of dissimilar materials connected electrically in series and thermally in parallel, and typically comprises a series of n-type and p-type semiconductor elements connected electrically in series and thermally in parallel. Depending on the direction of current passing through the thermoelectric device  46 , one surface will be heated and the opposing surface will be cooled. The thermoelectric device  46  generates a temperature differential that causes heat to transfer by conduction through the rotors  42 ,  44 . The greater the temperature differential, the greater the rate of heat transfer. The temperature differentials and efficiencies are expected to increase as the technology improves. 
   The rotors  42 ,  44  comprise annular heat exchangers in direct thermal communication with the thermoelectric device  46  to conduct heat throughout the rotors  42 ,  44 , primarily by thermal conduction to thereby form a short thermal path length between the rotors  42 ,  44  and the thermoelectric device  46 . Depending on the material and construction of the rotors  42 ,  44 , the rate of thermal conduction will vary. The rotors  42 ,  44  also allow air to pass outward, such as in a radial direction, through the heat exchanger, and further comprise blades of fans that cause the air to pass outward through the rotors  42 ,  44 . The heat exchanger thus forms the fan that causes the air to flow through the heat exchanger. Alternatively phrased, the fan that generates the air flow also forms the heat exchanger. In one embodiment, the fins of the heat exchanger comprise the blades or airfoils of the fan generating the air flow. Alternately, the heat exchanger could comprise a series of heat exchange surfaces that are configured to generate an airflow when the surfaces are rotated. 
   The rotors  42 ,  44  are advantageously formed by taking a length of heat exchanger of aluminum or copper that is formed from a flat strip of metal having corrugated or accordion-like pleats folded so heat sinks and sources can be connected at the ends of the pleats where the metal folds to change direction. The pleats are orientated so air can flow along the corrugations of the heat exchanger. The opposing ends of that length of heat exchanger are curved toward each other, and then overlapped and fastened together either mechanically or by thermal or adhesive bonding. This bending forms the previously straight length into a circle so the air flows radially through what is now a circular heat exchanger. In this annular configuration the heat exchanger can effectively act as the blades of a squirrel cage fan or a circular fan. This method is advantageously, but not necessarily, used to form both the first rotor  42  and the second rotor  44 . 
   In the illustrated embodiment, the first rotor  42  is located on the supply side of the heat exchanger that supplies conditioned air to a user, and has an outer diameter that is smaller than the diameter of the second rotor  44 . The second rotor  44  is located on the waste side of the system and exhausts conditioned air, advantageously to a location that does not direct air to the supply side or that otherwise directs air to a location that could affect the user. Each of the components are axially aligned to rotate about a central axis aligned with a drive shaft or axle  52  of motor  50 . A disc-shaped connector  51  having a central aperture is disposed on top of the first rotor  42  and the motor  50 . The motor  50  may be directly coupled to the axle  52  or could be indirectly coupled, such as via a gear assembly. 
   The connector  51  mechanically couples at least one of the shaft  52  or motor  50  to the first rotor  42  so that the motor  50  is configured to rotatably drive the first rotor  42 , the thermoelectric device  46 , and the second rotor  44  about a common axis, as described in more detail below. The interior diameter of rotors  42 ,  44  is advantageously large enough to allow motor  50  to be inserted inside the space formed inside the annular rotors  42 ,  44 , to minimize the height of the unit along the longitudinal axis about which rotors  42 ,  44  rotate. 
   As shown in  FIG. 3 , the rotor assembly  30  is mounted within the outer housing  32  on a drive axle  52  that, in the illustrated embodiment, is journaled at opposing ends of the axle on shaft bearings  54  which are advantageously mounted to walls  31 ,  33 . The drive axle  52  of the rotor assembly  30  is axially aligned with the first and second inlets  38  and  40  of the outer housing  32 . The outer housing  32  could also be equipped with only a single inlet or with more than two inlets. 
   The plane of the thermoelectric device  46  defines a boundary line  56  that divides the interior cavity  29  into an upper portion or supply side  58  and a lower portion or waste side  60 . The first rotor  42  is located within the upper portion or supply side  58  and the second rotor  44  is located within the lower portion or waste side  60 . 
   As shown in  FIG. 3 , the rotor assembly  30  further includes a first annular plate  63  that is disposed between a top edge of the thermoelectric device  46  and a bottom edge of the first rotor  42 . A second annular plate  65  is disposed between a bottom edge of the thermoelectric device  46  and the top of the second rotor  44  so that the thermoelectric device  46  is interposed between the first and second plates  63  and  65 . The first and second plates  63  and  65  are preferably manufactured of a material that is thermally conductive but is electrically insulative, such as, for example, alumina. In one embodiment, a heatresistant, thermally-conductive adhesive, such as silver-filled silicon adhesive, is used to mount the first rotor  42  to the first plate  63  and the second rotor  44  to the second plate  65 . Alternately, plates  63  and  65  may be omitted and the first and second rotors  42  and  44  may be directly attached to the thermoelectric device  46 . 
   An annular, disc-like insulation member  64  of thermally insulated material extends from between the rotors  42 ,  44 , radially outward and ends before it hits the inside of the side walls  35 . Advantageously the member  64  is positioned on top of the second annular plate  65  adjacent the inner and outer periphery of the thermoelectric device  46  and is placed generally in the plane containing boundary line  56 . The insulation member  64  is dimensioned to extend radially inward and outward from the thermoelectric device toward the motor  50  along the boundary line  56 . A gap  66  is defined between the outer periphery of the insulation disc  64  and the interior surface of the outer housing  32 , with the gap  66  forming an air bearing to reduce the passage of air across the gap  66 . 
   As shown in  FIGS. 3 and 4 , a thin and flexible annular seal  70  of thermally insulated material is positioned so as to extend radially inward from the interior surface of the outer housing  32  generally along the boundary line  56 . The annular seal  70  is preferably sized so that it overlaps, but does not contact the adjacent surface of the insulation member  64 . The annular seal  70  cooperates with the insulation member  64  to define a labyrinth seal around the outer periphery of the member  64  that thermally insulates the upper portion or supply side  58  of the interior cavity  29  from the lower portion or waste side  60  of the interior cavity  29 . The insulation member  64  and annular seal  70  prevent significant heat convection between the waste and main sides. The annular seal  70  can be in the form of an air bearing that facilitates rotation of the rotor assembly  30 . The insulation member  64  may comprise any of a wide variety of heat resistant, thermally-insulative materials, such as expanded polypropylene. 
   As illustrated in  FIG. 4 , at least a portion of the interior surface of the housing  32  advantageously is coated with a wicking material  78  that is adapted to absorb and conduct moisture. The wicking material  78  extends between the upper and lower portions  58 ,  60 , and advantageously comprises a woven cotton fabric that has been texture coated to prevent microbe growth. The wicking material  78  absorbs condensed moisture expelled by centrifugal force from whichever rotor  42 ,  44  produces the condensation, and conducts the moisture to the other rotor where it is evaporated by the heated air—in order to avoid accumulation in the interior cavity  33  and in passages distributing the cooled air. Advantageously the wicking material  78  absorbs enough moisture to prevent accumulation in the downstream passages in fluid communication with whichever rotor  42 ,  44  is cooled prompting a potential for condensation. 
   The annular seal  70  must allow the wicking material  78  to pass. Thus, the seal  70  may be connected to an exterior surface of the material  78 , may extend through the material  78  at intermittent locations, or may connect to side walls  35  at locations where the material  78  is absent. The material  70  could also extend outside of the interior cavity  33 . 
   As seen in  FIG. 3 , electrically-conductive wires  80  are electrically coupled to the thermoelectric device  46  to provide an electrical potential thereto in a well known manner through brushes  84  that are in electrical communication with the rotating drive axle  52 . Because electrical current must be provided to the thermoelectric device  46  in a closed circuit, two brushes  84  are in electrical communication with the axle  52  and thermoelectric  46  through brush and slip-ring assemblies known in the art. Other electrical connections, such as, for example, an inductive coupling, can be devised given the present disclosure. 
     FIGS. 5 and 6  are top and side views, respectively, of the first rotor  42 . The structure of the second rotor  44  may be identical to that of the first rotor  42 , although the respective dimensions may differ. The following more detailed description of the first rotor  42  is therefore equally applicable to that of the second rotor  44 . The first rotor  42  comprises a strip of corrugated metal having two connected ends so that the first rotor  42  is annular in shape. The corrugations or accordion-like pleats in the first rotor  42  form a series of radially-extending fins or blades  91  that define a series of radially-extending chambers or spaces  92  therebetween. As seen in  FIG. 4 , the width (i.e., the circumferential distance between adjacent fins  91 ) of the chambers  92  gradually increases moving radially outward from a center point  90  of the first rotor  42 . Each rotor  42  and  44  has an inner radius R 1  and an outer radius R 2 . The spacing between adjacent fins  91  is sufficiently wide at the inner radius R 1  to allow air flow radially outward through the rotor  42 . 
   In the illustrated embodiment, the blades  91  comprise generally flat walls that are connected and extend radially outward from a center point  90  on the rotational axis of the rotor  42 . This design is not believed optimum from the aerodynamic viewpoint of moving the maximum volume of air through the rotor  42  for a given rotational speed or rotor size. The blades  91  may also be more aerodynamically configured to provide various airflow profiles. For example, the blades  91  may be s-shaped, c-shaped, etc. Alternately, the blades  91  may comprise any type of straight or curved surface that produces an airflow when the surfaces are rotated. 
   The outer radius R 2  preferably ranges from approximately 12-75 mm when incorporated into a temperature control system for a motor vehicle seat. The radial length of the blade  91 , the difference between the inner radius R 1  and outer radius R 2 , is approximately 10-40 mm when the heat exchanger  28  is incorporated into a temperature control system for a motor vehicle seat, as described below with reference to FIG.  7 . The blades  91  may have a height measured along the rotational axis, in the range of approximately 6-15 mm when used with car seats. Adjacent blades  91  are preferably spaced apart a distance of approximately 0.5-2 mm for a temperature control system for a seat. The thickness of the blades  91  when made of copper or aluminum is preferably in the range of approximately 0.05-0.2 mm when incorporated into a car seat. 
   In an alternative embodiment, the thermoelectric device  46  is replaced by a resistive heating element which converts electrical energy into heat energy. This resistive heating element does not have the cooling capability of the thermoelectric device  46 , but it does provided heated air which may have wider applicability in certain climates. As illustrated in  FIG. 3 , in operation, the motor  50  rotates the axle  52  by activating the power source through a control, such as a manual switch or a thermostatically controlled switch. The motor is in driving communication with the first rotor  42 , the second rotor  44 , and the thermoelectric device  46  so as to rotate those components about the rotational axis of drive axle  52 . The rotation of the first rotor  42  creates a pressure differential that draws air into the supply side  58  of the interior cavity  29  through the first inlet  38 . The air flows into the spaces  92  and radially outward across the blades  91  of the first rotor  42 . The rotation of the rotor  42  imparts centrifugal force to the air that propels the air radially outward from rotor  42  so that the air travels out of the supply side  58  of the interior cavity  29  through the first outlet  34 . 
   In a similar manner, the second rotor  44  also rotates and draws are into the lower portion or waste side  60  of the interior cavity  29  through the second inlet  40  (or through either inlet  38  or  40  if only one inlet is provided). The air passes through the spaces  92  between the blades  91  of the second rotor  44 , radially outward across blades  91 , and is propelled out of the waste side  60  through the second outlet  36 . The divider  64  keeps the air flows from intermingling, and because it is thermally insulated, maintains a temperature differential between the supply side  58  and waste side  60 . 
   The electrical wires  80  also supply an electrical-current to the thermoelectric device  46 , advantageously through shaft  52 , so that the thermoelectric device  46  heats the rotor  42  and cools rotor  44 , or cools rotor  42  and heats rotor  44 , depending on which direction the electrical current flows through the thermoelectric divide  46 . As the air flows across the blades  91  of the first rotor  42  and the second rotor  44 , the air is either heated or cooled. That is, on the hot side of the thermoelectric device  46 , heat is transferred to the air from the heated fins of the rotor as the air flows thereover. On the cooled side of the thermoelectric device, heat is absorbed from the air as the air passes over the cooled rotor to thereby cool the air. The heat exchanger thus produces heated air through one outlet and cooled air through the other outlet. The heated or cooled air is then directed to the appropriate location in the seat for heating or cooling the passenger seat. The air with the undesired temperature is vented to a location where it will not noticeably affect the vehicle passengers. Preferably, the waste air is vented to a location such that the waste air is not drawn back into the outer housing  32 . 
   The first rotor  42  and the second rotor  44  simultaneously function as fan units for generating an airflow at a predetermined pressure and also as heat exchangers for transferring heat to and from the airflow and maintaining the airflow at the desired temperature. By combining the heat exchanger function into the fan that generates the air flow, several advantages are achieved. By forming the heat exchanger into an annular fan and nesting the motor inside the heat exchanger/fan, space and weight savings are achieved. 
   Current systems are about 45 mm in height, which is too big for many motor vehicles and other applications requiring a small size. Newly designed systems are about 30 mm in height, but a great number of motor vehicles still have seats too small to accommodate such fans underneath or around the seat, and few can accommodate that size within the seat. Fan and heat exchanger units  28  with a height below about 20-30 mm will accommodate a majority of automotive seats, and the present invention can allow such construction. But systems  28  of the present invention having a height of about 16 mm are believed possible, which is about half the height of the smallest systems currently available, and small enough to allow the use of the heating/cooling system inside a significant majority of seat bottoms and seat backs currently used in motor vehicles. The smaller size also benefits any application where size constraints are an issue. 
   This height reduction represents the distance between walls  31 ,  33  and associated ducting to carry the air to the location within the seat. The design of rotors  42 ,  44  can be used to vary the dimensions, with the heat exchanger surface area of blades  91  being a compromise between blade height, blade length, and diameter, and that area must be offset by the change in performance and rotational speed of the fan. Also, shorter rotors  42 ,  44  can be achieved by increasing the diameter of the rotors or by operating the rotors at higher speeds, which may increase noise. 
   Further, the design eliminates the interconnecting ducting between the fan and the heat exchanger, saving weight, size and pressure losses in the transmitted air. The small size also allows placement of heating and cooling systems directly in the seat bottoms and backs, further reducing the need for ducting, and especially reducing the need for ducting across the pivoted joints between seat bottoms and backs. The reduced ducting and its associated pressure losses and performance degradation, also allows the use of smaller fans, which use less energy and generate less noise. 
   Moreover, the consolidation of several parts and functions allows a reduced manufacturing cost and an increase in efficiency of the system. The drag normally caused by passing the air over the heat exchanger is significantly reduced because the heat exchanger forms the fan blades that generate the air flow. Further, adequate heating and cooling of a motor vehicle seat are believed to use about 1000 watts less than the power needed to provide the same comfort level to a passenger using the heating and cooling system of a motor vehicle—which must heat and cool the entire passenger compartment rather than the localized environment of the seat on which the passenger sits. 
   A further advantage is the reduction of noise because two small fans can be used. The rotors  42  and  44  preferably operate at a rotational speed in the range of approximately 2,000-5,000 revolutions per minute, although speeds of about 1000 rpm may be desirable in some applications, and higher speeds of up to 10,000 revolutions per minute in others. The rate of airflow of the main side of the heat exchanger is in the range of approximately 2-6 cubic feet per minute at a pressure of about 0.2-1 inches of water, with a flow rate of about 3-4 cfm being preferred. The rate of airflow of the waste side of the heat exchanger is in the range of approximately 2-10 cubic feet per minute, at a pressure of about 0.3-0.4 inches of water. The rotors  42 ,  44  with the blades acting as conductive heat exchanger as well as fan blades to move air, provide these needed air flows. In typical automobile use, 12 volt motors drive the rotors  42 ,  44 . This fan flow rate and pressure are smaller than in prior seat systems where the fan had to generate enough pressure and air flow to provide air to both the bottom and backrest portions of the seat. 
   To further enhance the above advantages, in a further embodiment the blades  91  may comprise a series of independent walls mounted on an annular plate where the blades  91  are contoured or curved to provide a preselected airflow profile when the first rotor  42  rotates, advantageously a profile that is more efficient than the straight blades  91  described above while still conducting heat well and maintaining a low manufacturing cost. Further, the blades  91  as illustrated and described above are not optimized for minimizing noise, and noise reduction is an important consideration for equipment operating inside the passenger compartment of motor vehicles. A more refined design of the blades  91  could advantageously reduce noise. It is believed that the level of noise generated by rotation of the rotors  42  and  44  generally decreases as the number of blades  91  increases. To accommodate the thermal transfer use of the rotor blades  91 , more blades are likely to be required than may be desirable for optimum performance if the rotors  42 ,  44  were designed solely for use as fans to move air—without regard to the heat transfer function and noise of the rotors  42 ,  44 . 
   The compact design also reduces the weight of the unit. As mentioned, the blades  91  are preferably manufactured of a thermally conductive material, such as pure annealed aluminum, carbon, and copper, which are known to be highly thermally conductive materials. Other material may be used as scientific advances in conductive material are made. While copper is heavier than aluminum, its increased thermal conduction properties offer advantages and design options in configuring the rotor blades  91  to perform both heat transfer and air movement functions. The blades preferably have a thermal conductivity rate of greater than about 12 w/m·°K. 
   The conditioned air that flows out of the first and second outlets  34  and  36  may be put to any of a wide variety of uses. In one embodiment, the heat exchanger  28  is incorporated into a ventilation system for vehicle seats, such as for automobiles, as described below with reference to FIG.  7 . It will be appreciated that the heat exchanger  28  could also be used in other applications as well. 
   As illustrated in  FIG. 7 , an automobile seat temperature control system  112  comprises at least one seat  114  and a pair of heat exchangers  28   a  and  28   b  (referred to collectively as “heat exchangers  28 ”) mounted therein. The heat exchangers  28  are of the type described above with reference to  FIGS. 1-6 . In the illustrated embodiment, the first heat exchanger  28   a  is mounted within a seat bottom  118  and the second heat exchanger  28   b  is mounted within a seat back  120 . The heat exchangers may also be mounted adjacent any portion of the seat  114 , such as below or on the side of the seat  114 . 
   The seat  114  has a series of channels  116  for the passage of air. An outer covering  117  of the seat  114  surrounds a padding layer  119  through which the channels  116  extend. The outer covering  117  is desirably perforated or air-permeable to allow air to flow therethrough from the channels  116 . The seat  114  also includes seat bottom  118  and seat back  120  extending upwardly therefrom for supporting a human body in a sitting position. The outer covering  117  may comprise any well known material for covering seats, such as perforated vinyl, cloth, perforated leather, etc. The padding layer of the seat  114  may comprise any well-known material for enhancing user comfort, such as reticulated foam. 
   As illustrated in  FIG. 7 , the first outlet  34  ( FIG. 1 ) of the first heat exchanger  28   a  is attached to channels  116  that extend through the seat back  114 . The first outlet  34  of the second heat exchanger  28  is attached to the channels  116  that extend through the seat bottom  118 . Each of the heat exchangers  28  is electrically coupled to a power source via a control switch so that a user may selectively power the heat exchangers via the power switch. A control switch is also coupled to the heat exchangers  28  for reversing the polarity of the electrical current applied to the heat exchangers  28  in a well known manner. The control switch is used to switch the heat exchangers  28  between a heating and a cooling mode. In the heating mode, the heat exchangers  28  pump heated air into the seat  114 . In the cooling mode, the heat exchangers pump cooled air into the seat  114 . The heat exchangers  28  may also be coupled to separate power and temperature controllers for providing independently-controlled conditioned airflow to the seat back  114  and the seat bottom  120 . 
   A feedback control system including a temperature sensor, such as a thermocouple, may also be provided. The system  112  may also be equipped with a control system for varying the speed of the rotors  42  and  44  to vary the flow rate. Those skilled in the art will appreciate that any of a wide variety of control devices may also be provided. 
   The channels  116  may comprise a series of plastic ducts or pipes that are coupled to at least one of the first and second outlets  34 ,  36  of the heat exchangers  28  and disposed within the seat  114 . Advantageously, the ducts may be formed by heat sealing the plastic foam of which the seat is made, or by coating the duct with a sealant to reduce air loss through the duct. The channels could also comprise air gaps within a permeable material, such as reticulated foam, that allow air to flow therethrough. Additionally, the channels may comprise any type of passage for the flow of air, such as ducts, pipes, small holes, etc. 
   Preferably, a main duct  137  is connected to the first outlet  34  for routing the cooled or heated air to the seat  114  surface  117  via the channels  116 . A waste duct  138  is connected to at least the second outlet  36  for routing the unwanted “waste” air to the outside environment away from the passenger occupying seat  114 . 
   In operation, the power switch is activated to supply an electrical current to the heat exchangers  28 . As discussed above, the thermoelectric device  46  and the main and second rotors  42  and  44  combine to generate a flow of heated or cooled air which is routed to the main ducts  137  and throughout the seat  114 . The conditioned air flows out of the channels  116  through the permeable outer covering  117  to thereby cool or heat the occupant of the seat  114 . Desirably, the waste air is routed away from the seats  114  through the waste ducts  138 . 
   The waste ducts  138  can advantageously vent below the seat bottom  118  because the heating and cooling system in the passenger compartment can produce typically over 20 times the amount of heat or cool air as is exhausted through waste duct  138 . As long as the waste ducts  138  do not vent directly on a passenger, toward a passenger, or on the inlets  38 ,  40  the environmental heating and cooling equipment will amply dissipate the output from waste ducts  138 . A waste duct  138  connecting unit  28   a  located in the back portion  119  can vent below the seat bottom  118  without having a duct extend across the pivoted joint between the bottom portion  118  and backrest  119 . Because the airflow of waste duct  138  is downward toward the seat bottom  118 , two aligned openings, one at the bottom of back portion  119 , and one in the seat bottom  118 , are sufficient to convey the air to below the seat bottom  118 . 
   As shown in  FIG. 8 , in another embodiment, the heat exchanger  28  is incorporated into a cooler, such as an ice chest  140 . In the illustrated embodiment, the ice chest  140  comprises a rectangular box that includes a base wall  144  and four side walls  146  extending upwardly therefrom. A lid  150  is pivotably mounted on the four side walls  146  in a well known manner to provide access to a storage space  152  defined by the walls of the ice chest  140 . The walls of the ice chest are desirably insulated in a well known manner to maintain the temperature of the storage space  152 . 
     FIG. 9  is a cross-sectional side view of the lid  150  of the ice chest  140 . At least one heat exchangers  28  of the type described above with reference to  FIGS. 1-6  is disposed within the lid  150 . The heat exchanger  28  is connected to a power source (not shown), such as a battery of the proper voltage and power, and is configured to operate in a cooling mode such that it outputs a flow of cold air at the first fan  42 , as described above. The heat exchanger  28  is rotatably mounted within the lid  150  such that the waste side of the heat exchanger  28  is positioned between top and bottom walls  156 ,  158 , respectively, with an insulation member positioned to thermally separate the main and waste sides. The main side of the heat exchanger  28  is disposed immediately below the bottom wall  158 . A cover unit  159  is positioned over the main side of the heat exchanger  28 . The cover unit  159  includes a series of apertures to allow air to flow through the main side of the heat exchanger  28 . The main side of the heat exchanger  28  is positioned within the storage space  152  of the ice chest  140  when the lid  150  is closed. 
   The waste side of the heat exchanger  28  is disposed between the top and bottom walls  156  and  158  of the lid  150 . An inlet  38  extends through the top wall  156  to allow air to flow into and out of the heat exchanger  28 . The lid  150  is preferably filled within insulative material around heat exchanger  28 . 
   In operation, the heat exchanger  28  is powered in the cooling mode so that the first fan  42  generates a flow of cooled air within the storage space  152  when the lid  150  is closed. In this manner, the storage space  152  is maintained at a relatively cool temperature. The heated waste air is routed to the outside environment such as through an outlet in the top wall  156  of the lid  150 . Any of a wide variety of articles, such as food, may be stored within the storage space  152 . 
   With reference to  FIG. 10 , there is shown a fan unit  200  that is configured to be mounted adjacent or within a standard desk. The fan unit  200  includes a housing  202  that is pivotably mounted to base  204 . The housing  202  is substantially cylindrical shaped and includes a conditioned air outlet  206  and one or more waste air outlets  208  around the periphery of the housing  202 . An air inlet  210  is located in the housing  200  opposite the conditioned air outlet  206 . A control switch  212  and a power cord  214  are coupled to the base  204  for selectively powering the fan unit  200  and/or the thermoelectric element  232  in a well known manner. 
     FIG. 11  is a cross-sectional view of the fan unit  200 . An annular duct  216  is disposed within the housing  202  and defines the conditioned air outlet  206 . A second duct  218  defines the waste air outlets  208 . A drive axle  220  is rotatably mounted within the housing so as to be axially-aligned with the conditioned air outlet  206 . In the illustrated embodiment, a motor  222  is drivingly coupled to the drive axle  220  via a drive belt  224 . A rotor assembly  226  is mounted to the drive axle  220  so that the rotor assembly rotates with the drive axle  220 . 
   The rotor assembly  220  comprises a main fan  228  adjacent the conditioned air outlet  206  and an annular waste fan  230  on the side of the main fan  228  opposite the conditioned air outlet  206 . A thermoelectric element  232 , such as a Peltier heat exchanger, is interposed between the main and waste fans  228  and  230 . The main fan  228  has a circumference that is less than or equal to the circumference of the conditioned air outlet  206  so that the main fan is configured to cause air to flow through the conditioned air outlet  206 . The waste fan  230  is positioned so to communicate with the waste outlet  208 . The main and waste fans  228  and  230  may comprise any type of device that is configured to produce an air flow upon rotation. In one embodiment, the fans comprises flat discs having louvers  234  punched therethrough. The fans are preferably manufactured of a highly thermally conductive material. 
   In operation, the motor  22  is powered through a power source (not shown) in a well known manner. The thermoelectric device  232  cools the main fan  228  and heats the waste fan  230  (or vice versa) in the manner described above with respect to the previous embodiments. The fans also rotate to produce a flow of conditioned and waste air through the conditioned air outlet  206  and the waste air outlet  208 , respectively. The air may be routed to cool a desired location, such as beneath a desk. If desired, ducts, hoses and other devices may be connected to the outlets to further direct the flow of air therefrom. 
     FIG. 12  shows another embodiment of a beat exchanger comprising a fan unit  170  having a plurality of air flow generating members, such as blades  172 , that rotate about an drive axle  174 . A motor  176  is drivingly connected to the axle  174 , either directly or indirectly, such as through a gear mechanism. One or more electrical heat generating devices, such as electrical resistors  180 , are mounted on the blades  172 . The resistors may be embedded within the blades  172  or may be painted thereon, such as with adhesive. 
   In operation, the resistors  180  are heated by applying an electrical current thereto and the axle  174  is rotated via the motor  176 . The blades  172  generate an airflow, which is heated by the resistors through a convective process. The fan unit  170  is thereby used to generate a heated airflow. 
   Given the above disclosure, other variations of this invention will be known to those skilled in the art. For example, the rotors  42 ,  44  are shown connected to the rotating shaft  52  by plate  51  located adjacent the first or upper wall  31 . In this configuration the interior cavity formed by the inner diameters of rotors  42 ,  44  are interconnected. It is believed possible to have the plate  51  contoured to the exterior shape of the top portion of motor  50  and then extend radially outward at about the plane containing the thermoelectric  46 . That would place a physical separation between the air flows entering rotors  42  and  44 . It is also believed possible to form the housing of motor  50  with a radial flange extending radially outward at about the plane containing boundary line  56 , with the motor  50  rotating, and thus provide a physical separation between the air flows entering the rotor  42  and  44 . 
   Enhanced embodiments of a thermoelectric heat exchanger which could be used in conditioned air seats and many other localized conditioned air applications are shown in  FIGS. 13-18 . 
   A first embodiment of an enhanced thermoelectric heat exchanger  1300  is shown in FIG.  13 A.  FIG. 13B  depicts a cross-section of the rotary heat exchanger  1300 .  FIG. 13C  depicts an auxiliary fan blade insert  1310  for the heat exchanger  1300 .  FIG. 13D  depicts a top view of the thermoelectric heat exchanger  1300  with the auxiliary fan  1310  in place. A thermoelectric device  1301  is attached so as to be in uniform and good thermal contact with a heat transfer member  1302 . A heat transfer fin array forming a first heat exchanger  1303  is in uniform and good thermal contact with the heat transfer member  1302 . The opposite side of the thermoelectric device  1301  is in uniform and good thermal contact with a second heat exchanger  1304 . In an alternative embodiment, a second heat transfer member (not shown) may be provided to conduct heat to the second heat exchanger  1304 . In the depicted embodiment, the thermoelectric device  1301  is arranged in a cylindrical form. Similarly, the heat transfer member  1302 , and heat exchangers  1303 ,  1304  are cylindrical in form. All are formed about a central axis. The heat exchanger array  1303  is oriented so that as the assembly spins, fluid (not shown) is ducted in a generally outward direction (or away from the central axis). The heat exchanger  1304  is oriented so that fluid passes along the axis of rotation of the assembly. 
   The thermal contacts can be made by any means that provide uniform thermal contact with low thermal resistance. Some Examples are braised, soldered, thermally conductive glue or thermally conductive grease joints. Alternately, the thermoelectric elements and the thermoelectric device may be integral with each other to achieve simplicity of manufacture, lower costs, reduce number of parts, improve thermal heat transfer or to achieve other advantages. For example, the fin array  1303  could be machined from an extension of the heat transfer member  1302  or the thermoelectric elements could be soldered to a suitable circuit pattern formed directly on a high thermal conductivity, electrical insulation layer on the heat transfer member. 
     FIG. 13C  depicts the auxiliary fan  1310  for the heat exchanger  1300 . The mounting hub  1312  of auxiliary fan  1310  may be inserted into the top of the central cylinder  1308  of the heat exchanger  1300 . In this manner, an annular gap or ring  1314  matches up with the upper exits of the heat exchanger  1304  blades. The auxiliary fan  1310  has fan blades  1316  which are configured to operate in conjunction with the heat exchanger fins  1304 . The fan hub&#39;s  1312  outside diameter is sized to be less that the inside diameter of the heat exchanger  1304 . Thus, the auxiliary fan, hub  1312  fits within the heat exchanger  1300 . Preferably, the auxiliary fan blades  1316  extend outward above the heat exchanger  1304 , as depicted in the top view of the auxiliary fan  1310  in place with the heat exchanger  1300  of FIG.  13 D. As assembled, when the assembly rotates, the auxiliary fan blades  1316  act to move fluid outward or away from the axis of rotation. This action draws the fluid through the heat exchanger  1304  along the axis of rotation and outward along the auxiliary fan blades  1316 . An assembly view in a housing will be explained in further detail in FIG.  14 . Preferably, some of the auxiliary fan blades  1316  have cut-outs  1318  to facilitate increased airflow from the heat exchanger  1304  through the open ring  1314  and radially outward along the fan blades  1316 . 
     FIG. 14  depicts a preferred embodiment of the rotary thermoelectric heat exchanger assembly  1400  having a heat exchanger  1300  with auxiliary fan, a motor and a housing. The thermoelectric device  1401 , heat transfer member  1402  and heat exchangers  1403  and  1404  are as described in  FIGS. 13A and 13B , and form the rotating heat exchanger  1300 . The heat exchanger  1304  is attached to an auxiliary fan  1427  and the motor rotor  1414  of an electric motor. The auxiliary fan  1427  corresponds to the auxiliary fan of FIG.  13 C. The motor rotor  1414 , fan assembly  1427  and rotating heat exchanger  1300  rotate as a unit. A filter  1407  surrounds the assembly fluid chamber  1408  formed by an outer wall  1429  and an inner wall  1410 . A flow directing member  1409  attached to the thermoelectric array  1401  guides fluid flow. Fan blades  1433  are part of the rotating auxiliary fan  1427 . A motor rotor  1414  and the thermoelectric array are attached to the auxiliary fan  1427 . A fluid chamber  1405  is formed by a wall  1431  and an insulator  1413 . A second chamber  1406  is formed by the insulator  1413  and the inner wall  1410 . 
   A contact  1424  is attached to the shaft  1415  of the motor rotor  1414  and mates with a stationary contact  1422 . An electrical wire and terminal assembly  1426  is attached to a rivet  1425  thence to a contact leaf  1423  and the contact  1422 . A second contact  1417  is insulated from the shaft  1415  by an electrically insulating sleeve  1416 . The contact  1417  mates with a contact  1418  that is attached to a contact leaf  1419  which, in turn, is in contact with a rivet  1420 , and thence, to a terminal assembly  1421 . 
   The motor rotor  1414  rotates on the motor base  1433  at a suitable velocity to draw fluid  1432  through the filter  1407  and radially inward through the duct  1408 . A first part of the fluid passes around the inner edge of the inner wall  1410  and through the heat exchanger  1403  and into the fluid chamber  1406 . A second portion of the fluid  1432  passes through the second heat exchanger  1404  and thence through the fan blades  1433  and to the fluid chamber  1405 . The fluids in the chambers  1405  and  1406  have been pressurized by the fan assembly  1427 . Electric current passes from the terminal assembly  1421  through the stationary contact  1418  to a contact  1417  that is electrically isolated from the shaft  1415 . The circuit of the thermoelectric array  1401  is connected to the contact  1417  and to the shaft  1415  so that current from the terminal assembly  1421  passes through the rotating thermoelectric assembly  1401  and to the shaft  1415 . The contact  1424  is electrically connected to the shaft  1415  and mates with the stationary contact  1422 . Current from the shaft  1415  passes through the contacts  1424  and  1422  the contact leaf  1423  the rivet  1425  to the terminal assembly  1426  completing the system circuitry. 
   The thermoelectric device circuitry is such that current flow in once direction causes the inner side of the thermoelectric device to become hot and the outer side to become cold. When the current is reversed, the inner side becomes cold and the outer side becomes hot. In the first case, the outer side of the thermoelectric device  1401  cools the heat transfer assembly  1402  due to thermal conduction; thence the heat exchanger fin array  1403  and the fluid  1432  being pumped to the fluid chamber  1406  are cooled. Advantageously, the heat exchanger  1403  comprises a fin array or other blade based heat exchanger. The fluid  1432  collected in the fluid chamber  1406  is thus cooled, and pressurized, and exits through an opening (not shown) where it can be used as a cooling medium. Similarly, the second portion of the fluid is heated by passing through the heat exchanger  1404  that has been heated by the hot side of the thermoelectric device  1401 . Advantageously, the heat exchanger  1304  comprises a fin array or similar blade based heat exchanger. The hot fluid  1423  is pumped to high pressure by the rotating fan blades  1433  and collects in the fluid chamber  1405 . The heated fluid  1432  exits through a port (not shown) as a source of heated fluid. Alternately, it is exhausted as waste heat, if cooling alone is required. 
   By reversing the direction of current flow, hot fluid will collect in the fluid chamber  1405  and cold fluid will collect in the fluid chamber  1406 . The rotational speed of the heat exchanger assembly and the current can be varied to achieve different pressures, fluid flow rates, and chamber temperatures. 
   Preferably, the insulator  1413  is designed to form an effective labyrinth seal where it is in proximity to the heat transfer array  1402  at  1412 . Convective heat transfer from the hot side to the cold side of the thermoelectric array preferably is further reduced by the inclusion of a thermally insulative seal  1411 . Preferably, the flow directing member  1409  is designed to keep fluid  1432  prior to entering the heat exchanger arrays,  1403  and  1404 , from stirring and thereby convectively transporting heat content from one array to the other. 
   The filter  1407  serves to remove particles and other contaminants from the fluid stream. For example, if the fluid is air containing hydrocarbon contaminants, the contaminants can be removed by incorporating activated charcoal or other suitable agent in the filter media. Similarly, the filter can have-layers of various porosity to remove particulates of different sizes at several locations within it, so as to increase capacity, lower pressure drop across the filter and achieve high filtration efficiency. 
     FIG. 15  depicts the left portion of another embodiment of a rotary thermoelectric heat exchanger  1500 . The axis of rotation of this design is about the centerline  1513 . Contacts, electrical connections to the thermoelectric device  1501  and exit ports for fluid  1505  are not shown. The right portion is a mirror image of the left portion, with the exceptions of the areas of the fluid chambers  1509  and  1510  which are portions of fan scrolls well-known to the art. 
   The outer surface of the thermoelectric device  1501  is in good, uniform thermal communication with a heat transfer member  1502 . The heat transfer member  1502  is divided into four sections, each relatively thermally isolated from one another compared with the thermal conductivity in the direction from the thermoelectric array  1501  to the rotary heat exchanger array  1503 . The rotary heat exchanger  1503  is similarly divided into four sections each in good, uniform thermal communication with a section of the heat transfer member  1502 . The thermoelectric device  1501  is attached in its inner surface to a rotary heat exchanger  1504 , which is divided into four sections, each preferably thermally isolated from the other. The above thermal isolation is consistent with the teachings of U.S. patent application Ser. No. 09/844,818, filed Apr. 27, 2001, which is incorporated by reference herein. 
   In general, in any of the embodiments in the description, the heat exchangers may be formed in segments or sections or in other manners to provide thermal isolation from section to section in the direction of fluid flow. 
   The rotary heat exchanger  1504  is mechanically attached to a rotor  1511  and fan blades  1519 . The rotor  1511  is attached to a motor rotor  1512 . The parts so attached rotate as a unit. A fluid chamber  1510  is formed by an outer wall  1514  and an insulator  1515 . A second chamber  1509  is formed by the insulator  1515  and an inner wall  1516 . A third chamber  1507  is formed by the inner wall  1507  and second outer wall  1518 . A filter  1506  surrounds the rotary thermoelectric heat exchanger  1500 . Fluid  1505  is drawn through the filter  1506 , thence through the fluid chamber  1507  where a first portion goes through the heat exchanger  1503  and a second portion through the heat exchanger  1504 . A flow directing member  1508  splits the fluid  1505  so that convective heat transfer is reduced from fluid stirring at the entrance to the rotary heat exchangers  1503  and  1504 . Current is passed through the thermoelectric as described in FIG.  14 . 
   If, for example, the outer side of the thermoelectric array  1501  is cooled, the thermal energy is transferred by the rotary heat exchanger  1502  cooling the first portion of the fluid  1506 . The rotational motion generates centrifugal forces on the fluid  1506  so that the cooled fluid  1506  enters the fluid chamber  1510  and is pressurized. The conditioned fluid exits through a port (not shown). In this example, the inner side transfers heat to the rotary heat exchanger  1504  and thence to a second portion of the fluid  1506 . The fan blades  1519  increase the pressure in the heated fluid  1506  and convey the fluid  1506  to the fluid chamber  1510 . The fluid  1506  exits the fluid chamber  1510  through a port (not shown). A seal  1517  prevents significant convective heat transfer between the cold and hot fluid  1506  streams. 
   This assembly is capable of greater cooling or more efficient operation than the design of  FIG. 14  due to the use of thermal isolation. As depicted, the heat transfer member  1502  and rotary heat exchangers  1503  and  1504  are divided into four sections. Other numbers of sections can be used. Performance increases with more sections and with higher material thermal conductivity. 
   In the preferred embodiment, the heat exchanger array  1503  is not aligned so that the fluid flows radially from the axis of the spin of the fan assembly  1511 . Advantageously, a system incorporates a fan duct  1520  on to the rotary heat exchanger  1503  so as to maintain thermal isolation while directing fluid flow through all sections. 
     FIG. 16  depicts another embodiment of a thermoelectric heat exchanger with thermal isolation . A cutaway portion of a rotary thermoelectric heat exchanger system  1600  is shown with the centerline  1621  to the right as in FIG.  15 . Again, contacts, thermoelectric circuitry, current flow and conditioned fluid exit ports are omitted for clarity. The system consists of a washer-shaped rotary thermoelectric device  1601  with a first rotary heat exchanger  1602  divided into four sections and a second rotary heat exchanger  1603  also divided into four sections, each in good, uniform thermal contact with the rotary thermoelectric array  1601 . These parts are attached to a fan assembly  1620 , which has two sets of fan blades  1608  and  1609 , and in turn is attached to a motor rotor  1619 . All of these parts rotate as a unit driven by the electric motor  1622 . 
   A filter  1606  surrounds the assembly. A first wall  1610  and an inner insulator or wall  1618  form a fluid chamber  1607 . A second fluid chamber  1613  is formed by the inner wall  1618  and an insulator  1611 . A third chamber  1614  is formed by the insulator  1611  and a second wall  1612 . 
   As in  FIG. 14 , by way of example, when suitable current is passed through the rotary thermoelectric device  1601  the side in thermal contact with the rotary heat exchanger  1602  is cooled, and the opposite side is heated. If the current is reversed, the cold side becomes hot, and the hot side becomes cold. 
   Fluid  1606  passes through the filter  1605  and flows along the chamber  1607 . A first portion passes through the rotary heat exchanger  1602  where, for example, it is cooled and then goes into the fluid chamber  1613 . A second portion passes through the rotary heat exchanger  1603  where it is heated and then goes into the fluid chamber  1614 . The rotation of the fan assembly  1620  pressurizes the fluid in the fluid chambers  1613  and  1614 . Advantageously, a flow-directing member  1604  serves to prevent stirring of the fluid  1606  as previously discussed in FIG.  14 . 
   The rotary heat exchangers  1602  and  1603  are formed in sections to increase performance through thermal isolation in the direction of fluid flow as referenced in FIG.  15 . 
     FIG. 17  depicts a section of a rotary thermoelectric heat exchanger assembly  1700  with a centerline  1716  at the right. A rotary thermoelectric device  1701  is in good, uniform thermal contact with a rotary heat transfer member  1703  that is divided into sections and thence, to a rotary heat exchanger  1702 , which is divided into corresponding sections. The other side of the rotary thermoelectric array  1701  is attached to a rotary heat exchanger  1704  that is divided into sections, and is attached to a fan assembly  1719 . As with the prior figures, the division into sections or segments provides thermal isolation in the direction of fluid flow to increase efficiency of the unit. The fan assembly  1719  contains fan blades  1712 . It is attached to a motor rotor  1714 . Preferably, all parts attached to the fan assembly  1719  rotate in unison. 
   A chamber  1708  is formed by an upper wall  1721  and first insulator or wall  1720 . A fluid chamber  1710  is formed by the first insulator  1720  and an insulator  1713 . A chamber  1707  is formed by the insulator  1713  and a second insulator or wall  1709 . A fluid chamber  1711  is formed by the insulator  1709  and a lower outer wall  1718 . A filter  1706  surrounds the assembly. 
   The operation of the rotary thermoelectric heat exchanger  1700 , is similar to that of  FIG. 15 , except that the fluid  1705  flows in a generally upward direction through the heat exchanger  1702  and downward through the heat exchanger  1703 . In accordance with the teachings of patent application Ser. No. 09/844,818, this can further improve efficiency in some circumstances over that of the configuration of FIG.  15 . 
   As in  FIG. 15 , if fluid  1706  flows on one side of the rotary thermoelectric array  1701 , it can be heated and the other side cooled. 
   The system of  FIG. 17  incorporates two walls  1709  and  1715  that separate flows by providing suitable barriers to convective heat transport between the hot and cold side fluids. The wall or flow directing member  1715  plays a similar role, and also acts to direct and smooth the flow of fluid  1705  as it enters the rotary heat exchanger  1704 . It also incorporates a duct  1717  for the same purposes described in FIG.  15 . 
     FIG. 18  depicts a portion of a thermoelectric heat exchanger system  1800 , in which the heat exchangers  1802  and  1803 , and the thermoelectric device  1801  are generally pancake-shaped, are stationary and are attached to an insulator  1813 . The portion shown is generally rotationally symmetrical about the centerline  1816 . The parts can be of the same general structure as those described in FIG.  16 . Omitted for clarity, are details of electrical circuitry current paths and terminals that power the thermoelectric element array  1801 . However, in this configuration, no contacts are required as the thermoelectric array is stationary. 
   A fan assembly  1812  with the fan blades  1809  is attached to a motor rotor  1808 . A filter  1805  is attached to the lower part of the assembly; with its upper most surface positioned by grillwork or radial ribs  1806 . The filter  1805 , an insulated flow directing member  1815  and fan assembly  1812  form a chamber  1807 . A first fluid chamber  1810  is formed by a portion of the insulated flow directing member  1815  and the insulator  1813 . A second fluid chamber  1811  is formed by the insulator  1813  and a wall  1814 . 
   Fluid  1804  passes through the filter  1805  into the chamber  1807 . The fluid  1805  is pressurized as it passes by the fan blades  1809 . A first portion passes through the heat exchanger  1802  where, for example, it is cooled. The cooled fluid  1805  passes into a chamber  1810  from where it exits the assembly through a port (not shown). A second portion of the fluid is heated as it passes through the heat exchanger  1803  and enters the chamber  1811 . It exits the assembly through a port (not shown). 
   As with the previous embodiments of  FIGS. 15 ,  16  and  17 , the heat exchangers  1802 ,  1803  are formed in sections or segments to provide thermal isolation in the direction of fluid flow. As explained above, this improves efficiency of the thermal electric system. 
   The method and apparatus of the present invention are applicable to many uses, such as seats and wheelchairs, but it is not limited to use in seats. The method and apparatus is useful anywhere a localized flow of conditioned air is desired. 
   The present apparatus and method is not limited to the use of air or other gases. Indeed, some gases, such as helium, have greater thermal conductivity than air and are desirable in certain applications, while other gasses such as oxygen, nitrogen or argon may be more desirable in other applications. A variety of gases and gas mixtures can be used as the particular application requires. 
   Further, liquids can be used with the present invention. By applying appropriate liquid seals and insulators known in the art, the liquid circulating through the heat exchanger can be kept from affecting the performance of electrical contacts, the thermoelectric device, and any other electrical components. Thus, liquids such as water and antifreeze are contemplated for use with the present method and apparatus, as are liquid metals such as liquid sodium. Also contemplated are slurries of fluids and solids. The particular fluid used will depend upon the application. The increased thermal conductivity achieved by passing liquids over the rotating heat exchanger offer the possibility of increased heat conduction over that of less dense and less conductive gases. Whether a liquid or gas is most advantageous will vary with the particular application. For ease of reference, the term “fluid” is used to refer to gases, liquids, slurries and combinations thereof. 
   Because the temperature change available from a thermoelectric system can be significant, the rotating heat exchangers of the present invention have potential applicability to a wide variety of uses. The method and apparatus described herein are generally applicable to any situation where there is a desire to pump a thermally conditioned fluid. Such applications include constant temperature devices, as for example devices using a reference temperature as in a thermocouple assembly. Another exemplary application is in componentry for constant temperature baths for laboratory equipment and experiments. The method and apparatus described herein are particularly useful for applications requiring low flow rates and/or small temperature changes, but the invention is not so limited and may find application in situations requiring large flow rates and/or substantial temperature differences. 
   By placing a temperature sensor at a predetermined location, whether on the heat exchanger, the rotating fan, upstream or downstream of the heat exchanger, and electronically controlling the thermoelectric and the fan rotation, a controlled stream of thermally conditioned fluid can be provided to maintain the temperature at a predetermined temperature, or to provide predetermined thermal conditions. Thus, the invention provides advantages where localized thermal control is desired, as in vehicle seats, waterbeds, aquariums, water coolers, and cooling of beverages such as wine and punch. 
   Further, this device and method find particular application in situations where a fluid of differing temperature is desired at various times. The device may be operated as a fan capable of heating and cooling. The thermoelectric aspect can be activated when desired to thermally condition the fluid. Thus a heated, cooled, or neutral temperature fluid can be provided by the same device and method. 
   Although the foregoing description is of several preferred embodiments and has shown, described, and pointed out certain novel features of the inventions, it will be understood that various omissions, substitutions, combinations and changes in the form of the detail of the apparatus as illustrated as well as the uses thereof, may be made by those skilled in the art without departing from the spirit of the present invention. Also, one or more various components of one figure or embodiment may be used in different combinations with components of other figures to produce specific combinations not pictured in any one figure. For example, the fluid flow direction through heat exchanger  1802  of  FIG. 18  could be reversed by adding an insulating wall to the end of the thermoelectric device  1801  so as to create an additional fluid chamber. In this example, the fluid would be pulled toward the rotational axis and then could be pumped outward through a second fan blade attached to fan rotor  1812  and exit in a generally radially outward direction through yet an additional fluid chamber with its lower side formed by the insulated flow directing member  1815 . Thus, in this example,  FIG. 18  is combined with opposing flow as described in  FIG. 17 , has the number of flow passages of  FIG. 17 , and the number of fan blades that are not heat exchangers of FIG.  16 . Consequently, the scope of the present invention should not be limited by the foregoing discussion, which is intended to illustrate rather than limit the scope of the invention. The words used in the attached claims are used in their ordinary meaning sense, with no special or restrictive meaning intended by anything stated in the above description.