Abstract:
An improved thermoelectric power generation system utilizes rotary thermoelectric configurations to improve and increase thermal power throughput. These systems are further enhanced by the use of hetrostructure thermoelectric materials, very thin plated materials, and deposited thermoelectric materials, which operate at substantially higher power densities than typical of the previous bulk materials. Several configurations are disclosed.

Description:
PRIOR RELATED PROVISIONAL AND PATENT APPLICATIONS  
       [0001]    This Application is related to and claims the benefit of the filing date of prior filed U.S. Provisional Patent Application No. 60/267,657, file Feb. 9, 2001. This application is a continuation-in-part of U.S. patent application Ser. No. 10/074,543, filed Feb. 11, 2002, and a continuation-in-part of U.S. patent application Ser. No. 09/971,539 filed Oct. 2, 2001, and a continuation-in-part of U.S. patent application Ser. No. 09/918,999, filed Jul. 31, 2001 and a continuation-in-part of U.S. patent application Ser. No. 09/844,818 filed Apr. 27, 2001. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to the field of power generation using thermoelectric devices.  
           [0004]    2. Description of the Related Art  
           [0005]    Although it has long been understood that thermoelectric devices can be used to generate power, thermoelectric power generation has been little utilized because the efficiency of present generator design and the power density of such generators are too low.  
           [0006]    Historically, solid-state electrical power generating systems are constructed from TE Modules or stand-alone TE elements placed between a source of heat and a heat sink. The parts are designed with no moving parts in the power generator its self. Generally, systems that use hot and cold working fluids as the hot and cold sources employ fans to transport the fluids to the assembly.  
           [0007]    In other applications, pressurized air and fuel are combusted within the generator. Still in other applications, such as automotive exhaust waste power converters, heat is transported to the generator by the exhaust system. In these devices, the waste heat is removed either by external fans supplying coolant or by free convection through finned radiators.  
           [0008]    In applications such as generators that employ nuclear isotopes as the heat source, individual TE elements are configured to produce electrical power. Each TE element is attached to an isotope heat source on the hot side, and to a waste heat radiator on the cold side. No parts move during operation.  
         SUMMARY OF THE INVENTION  
         [0009]    New hetrostructure thermoelectric, quantum tunneling, very thin plated, and deposited thermoelectric materials operate at substantially higher power densities than typical of the previous bulk materials and offer the potential for higher system efficiency.  
           [0010]    Successful operation of thermoelectric devices with high power density requires high heat transfer rates both on the cold and hot side of TE Modules. One way to achieve this is through rotary designs that lend themselves to high fluid flow rates, and hence, high thermal power throughput. In one preferred embodiment, rotary systems in which a portion of the heat exchanger acts as fan blades, and thereby contributes to working fluid flow, can reduce power into the fan, simplify system design and reduce size.  
           [0011]    Further, the heat transfer rate in many systems can be increased by employing heat pipes, as is well known to the art. Such devices use two-phase (liquid and vapor) flow to transport heat content from one surface to another. Where heat is to be removed at a heat source surface, the fluids&#39; heat of vaporization is utilized to extract thermal power. The vapor flows to a surface at a lower temperature at the heat sink side where it condenses and thus gives up its heat of vaporization. The condensed fluid returns to the heat source side by capillary action and/or gravity.  
           [0012]    Properly designed heat pipes are very efficient and transport large thermal fluxes with very low temperature differential. Some keys to efficient operation are that the liquid return process be efficient and that the entire heat source side be wetted at all times, to make liquid always available to evaporate and carry away thermal power. Similarly, it is important that the cool, sink side does not accumulate liquid since heat pipe working fluids are usually relatively poor thermal conductors. Thus, the sink side should shed liquid efficiently, to maintain effective thermal conductance surface.  
           [0013]    In one embodiment, discussed herein, properly oriented heat pipes are combined with rotating heat exchange members, to utilize the centrifugal forces induced by rotation of the heat exchangers to improve performance. Rotary acceleration produced by fans and pumps can be up to several thousand Gs, so that with proper design, the liquid phase can be transported from the heat sink side to the heat source side very efficiently. Designs in which the colder end is closer to the axis of rotation than the hotter end, can exhibit very desirable heat transport properties because the centrifugal forces advantageously increase liquid phase flow when. As a result, such designs have increased power density, and reduced losses.  
           [0014]    Finally, power generators that are combined with thermal isolation as described in U.S. patent application Ser. No. 09/844,818, entitled Improved Efficiency Thermoelectrics Utilizing Thermal Isolation can further increase performance.  
           [0015]    One aspect described involves a thermoelectric power generator having at least one rotary thermoelectric assembly that has at least one thermoelectric module. The at least one rotary thermoelectric assembly accepts at least one working fluid and converts heat from the working fluid into electricity. Advantageously, the at least one rotary thermoelectric assembly comprises at least one hotter side heat exchanger and at least one cooler side heat exchanger. In one embodiment, the at least one hotter side heat exchanger has at least one hotter side heat pipe in thermal communication with the at least one thermoelectric module and a plurality of heat exchanger fins in thermal communication with the at least one hotter side heat pipe. In one embodiment, the at least one cooler side heat exchanger has at least one cooler side heat pipe in thermal communication with the at least one thermoelectric module and a plurality of heat exchanger fins in thermal communication with the at least one cooler side heat pipe. In one embodiment, the least one working fluid is at least one hotter and at least one cooler working fluid.  
           [0016]    Preferably, the heat pipes contain a fluid, and the heat pipes are oriented such that centrifugal force from the rotation of the rotary thermoelectric assembly causes a liquid phase of the fluid to gather in a portion in said heat pipes. For example, the fluid in the cooler side heat pipes is in a liquid phase at at least a portion of an interface to the at least one thermoelectric module, and the fluid in the hotter side heat pipes is in a vapor phase at at least a portion of an interface to the at least one thermoelectric module.  
           [0017]    In one embodiment, a motor coupled to the at least one rotary thermoelectric assembly spins the at least one rotary thermoelectric assembly. In another embodiment, the least one working fluid spins the at least one thermoelectric assembly. Preferably, the spinning pumps the working fluid through or across the heat exchangers, or both through and across the beat exchangers.  
           [0018]    In one preferred embodiment, the at least one rotary thermoelectric assembly has a plurality of thermoelectric modules, at least some of the thermoelectric modules thermally isolated from at least some other of the thermoelectric modules. In another embodiment, the at least one hotter side heat exchanger has a plurality of portions substantially thermally isolated from other portions of the hotter side heat exchanger.  
           [0019]    Another aspect described herein involves a method of generating power with at least one thermoelectric assembly having at least one thermoelectric module. The method involves rotating the at least one thermoelectric assembly, passing at least one first working fluid through and/or past a first side of the at least one thermoelectric assembly to create a temperature gradient across the at least one thermoelectric module to generate electricity, and communicating the electricity from the at least one thermoelectric module. In one embodiment, the method also involves passing at least one second working fluid through and/or past a second side of the at least one thermoelectric assembly. The rotation may be obtained in any number of ways, such as with a motor, with the working fluid itself, and in any other feasible manner to spin the thermoelectric assembly.  
           [0020]    Preferably, the at least one thermoelectric assembly has at least one first side heat exchanger and at least one second side heat exchanger, and the step of passing the at least one first working fluid involves passing the at least one first working fluid through and/or past the first and/or second side heat exchanger.  
           [0021]    As with the apparatus, in one embodiment, the at least the at least one first side heat exchanger has at least one first side heat pipe in thermal communication with the at least one thermoelectric module and a plurality of heat exchanger fins in thermal communication with the at least one first side heat pipe. Advantageously, the heat pipes contain a fluid and are oriented such that centrifugal force from the rotation of the at least one thermoelectric assembly causes a liquid phase of said fluid to gather in a portion in said heat pipes. The configurations for this method are as with the apparatus.  
           [0022]    Another aspect described involves a thermoelectric power generation system having a source of at least one hotter working fluid, a source of at least one cooler working fluid, and at least one rotary thermoelectric assembly having at least one thermoelectric module, wherein the rotary thermoelectric assembly accepts the at least one hotter working fluid and converts heat from the hotter working fluid into electricity. Preferably, the system also has an exhaust for the at least one hotter and the at least one cooler working fluids, and at least one electrical communication system to transfer electricity from the rotary thermoelectric assembly.  
           [0023]    In one embodiment, the at least one rotary thermoelectric assembly comprises at least one hotter side heat exchanger and at least one cooler side heat exchanger. As with the previous method and apparatus discussion, in one embodiment, at least the at least one hotter side heat exchanger has at least one hotter side heat pipe in thermal communication with the at least one thermoelectric module and a plurality of heat exchanger fins in thermal communication with the at least one hotter side heat pipe. Similarly, in one embodiment, at least the at least one cooler side heat exchanger may have at least one cooler side heat pipe in thermal communication with the at least one thermoelectric module and a plurality of heat exchanger fins in thermal communication with the at least one cooler side heat pipe. Thermal isolation may also be utilized.  
           [0024]    These and other aspects and benefits of the present description will be apparent from the more detailed description of the preferred embodiments below. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    FIGS.  1 A- 1 C depict a general arrangement of a thermoelectric generator that hot and cold fluids a motor and heat exchanger fins to create a temperature differential across a TE Module. Electrical power is produced from the thermal power within the hot side fluid stream.  
         [0026]    [0026]FIG. 1G further depicts a general arrangement of a thermoelectric generator in which the flow and pressure of a working fluid spins the generator assembly, thus eliminating the need for the electric motor shown in FIGS. 1C and 1D  
         [0027]    [0027]FIG. 2A depicts a TE Module, heat pipes and heat exchanger assembly for generally axial fluid flow in a rotary solid-state power generator.  
         [0028]    [0028]FIG. 2B gives a detailed cross sectional view of the assembly of FIG. 2A  
         [0029]    [0029]FIG. 2C gives a second view of a segment of the assembly of FIG. 2A.  
         [0030]    [0030]FIG. 3A depicts a sectional view of a TE Module, heat pipes and heat exchanger assembly for generally radial fluid flow in a rotary power generator.  
         [0031]    [0031]FIG. 3B shows a detailed, cross-sectional view of the assembly of FIG. 3A.  
         [0032]    [0032]FIG. 4 depicts an axial flow power generator wherein the hot and cold fluids flow generally parallel to one another in the same general direction. The generator utilizes thermal isolation and heat pipes to improve energy conversion efficiency.  
         [0033]    [0033]FIG. 5 depicts a radial flow power generator wherein the hot and cold fluids flow generally parallel to each other in the same direction. The generator utilizes thermal isolation and heat pipes to improve efficiency.  
         [0034]    [0034]FIG. 6 depicts an axial flow generator with hot and cold fluids flowing in generally opposite directions to one another. Advantageously, the TE Modules and heat exchangers are thermally isolated to improve efficiency and increase power density.  
         [0035]    [0035]FIG. 7 depicts a radial flow generator with the hot and cold fluids flowing generally in opposite directions. Advantageously, the TE Modules are thermally isolated. Heat pipes are employed to both increase efficiency and power density.  
         [0036]    [0036]FIG. 8 depicts a power generator with both generally radial and axial flows. A solid conductive heat transfer member is utilized to transfer heat between the TE Module and the hot side fin.  
         [0037]    [0037]FIG. 9 depicts a portion of an axial flow power generator in which current flows through TE elements or modules and heat pipes in a circular direction about the axis of rotor rotation.  
         [0038]    [0038]FIG. 10 depicts a system block diagram of a thermoelectric power generator. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0039]    In the context of this description, the term Thermoelectric Module or TE Module are used in the broad sense of their ordinary and customary meaning, which is (1) conventional thermoelectric modules, such as those produced by Hi Z Technologies, Inc. of San Diego, Calif., (2) quantum tunneling converters (3) thermoionic modules, (4) magneto caloric modules, (5) elements utilizing one, or any by combination of, thermoelectric, magneto caloric, quantum, tunneling and thermoionic effects, (6),) any combination, array, assembly and other structure of (1) through (6) above.  
         [0040]    In this description, the words cold, hot, cooler, hotter and the like are relative terms, and do not signify a temperature range. For instance, the cold side heat exchanger may actually be very hot to the human touch, but still cooler than the hot side. These terms are merely used to signify that a temperature gradient exists across the TE Module.  
         [0041]    In addition, the embodiments described in this application are merely examples, and are not restrictive to the invention, which is as defined in the claims.  
         [0042]    FIGS.  1 A- 1 F depict a general arrangements for a rotary thermoelectric power generator  100 . FIG. 1A is a perspective view. FIG. 1B is a view of a rotor assembly  135  as visible through the slots  126  of FIG. 1A. FIG. 1C is a cross section through the rotary thermoelectric power generator  100 . FIGS.  1 D- 1 F provide additional detail for various portions of the generator. A rotor assembly  135  (best seen in FIGS. 1B and 1C) is comprised of TE Module  101 , in good thermal contact with hot side heat exchanger  102 , such as heat transfer fins, on one side and a cold side heat exchanger  103 , such as heat transfer fins, on the other. Insulation  109  separate hot and cold sides. Insulation  109  rigidly connects the rotor parts to a motor rotor  110 . The TE Module  101  is depicted here for explanatory purposes and is comprised of TE elements  104  and circuitry  129 . At contact points  124 ,  125 , wires  123  electrically connect TE Module  101  to portions  117 ,  119  of shaft assembly  130  that are electrically isolated from each other, TE Module  101 , hot side heat exchanger  102 , cold side heat exchanger  103 , insulation  107 ,  109 , wiring  123 , circuitry  129  and shaft portions  117 ,  119  all form a rigid rotatable unit.  
         [0043]    Motor assembly  111  is connected to motor rotor  110  by bearings  144  (FIG. 1F). Slip ring contact  118  is in electrical communication with shaft member  119 , and slip ring contact  120  is in electrical communication with shaft member  117 . Wiring  122  connects to slip ring contacts  118  and  120  through circuitry  132  and other circuitry not shown, such as traces on a circuit board or other conventional circuit connections. Wiring  122  also connects to motor assembly  111 , through a circuit board  112  and other circuitry not shown.  
         [0044]    Spokes  113  (best seen in FIG. 1A) mechanically attach inner wall  114  (of FIG. 1 C) to motor base  116  and thereby to the motor assembly  111 . Hot side fluid filter  128  is attached to outer housing  131 , and cold side fluid filter  127  is supported by vanes  115  and attached to an extension  133  of outer housing  131 . Openings  126  in the outer housing, such as slots, allow fluid  106 ,  108  passage through outer housing  131 . A hot working fluid  105 ,  106  (FIGS. 1C and 1D) is confined to a chamber defined by outer wall  131 , openings  126 , insulation  109 , filter  128  and TE Module  101 . Cold working fluid  107 ,  108  is confined by inner wall  114 , vanes  115 , outer housing extension  133 , motor base  116  and filter  127 .  
         [0045]    Hot fluid  105  passes through the hot side filter  128  and transfers heat to the hot side heat exchanger  102 . The interface between the hot side heat exchanger  102  and TE Module  101  is thus heated. Similarly, cold fluid  107  passes through cold side filter  127  and absorbs heat from cold side heat exchanger  103 . Thus, the interface between the cold side heat exchanger  103  and TE Module  101  is cooled. The temperature gradient (heat flow) across the TE Module  101  generates electrical power. The electrical power is transferred through wires  123 , to conduct points  124 ,  125 , to shaft portions  117 ,  118  and through slip ring contacts  118 ,  120  and to wires  122  (best seen in FIG. 1F).  
         [0046]    Motor assembly  111  acting on motor rotor  110  spins the rotor assembly. In one embodiment, the heat exchangers  102 ,  103  are configured as fins oriented longitudinally away from the axis of rotation of the rotor assembly. In this configuration, the heat exchangers  102 ,  103  advantageously act as fan blades of a centrifugal fan or blower and thereby continuously pump working fluids  105 ,  107  in order to maintain a temperature differential across TE Module  101 . A portion of the heat flow across TE Module  101  is continuously converted to electrical power. Hot working fluid  105  is cooled as it passes through the hot side heat exchanger  102  and exits as waste fluid  106  through openings  126 . Similarly, cold working fluid  107  is heated as it passes through cold side heat exchanger  103  and exits as waste fluid  108  through openings  126 .  
         [0047]    The benefits of this rotational thermoelectric power generator will be explained in detail with specific configurations for the rotary assembly  135  in the following figures. The rotation of the heat exchanger thermoelectric module as a unit allows one or more heat exchangers to be used as fan blades for pumping the working fluid. In addition, other benefits and uses for rotation may be obtained in increasing the efficiency of the power generation system and increasing power density, as further explained below.  
         [0048]    [0048]FIG. 1D depicts a closer view of cold and hot side working fluid movements for the power generator  100 . The TE Module  101  is in good thermal communication with the hot side heat exchanger  102  and a cold side heat exchanger  103 . The two sides are separated by insulation  109 . Hot side fluid  105  and  106  is contained by an outer wall  131  and insulation  109 . Similarly, cold side fluid  107 ,  108  is contained by the inner wall duct  114  and insulation  109 . Motor rotor  110  is rigidly attached to insulation  109  so that insulation  109 , TE Module  101  and heat exchangers  102 ,  103  move as a unit. Wires  123  connect TE Module  101  to rotary slip rings  118 ,  120  as described in more detail in the discussion of FIG. 1F. Motor rotor  110  is connected through bearings  144  (FIG. 1F) to motor driver  140  and shaft  130  (shown in detail in FIG. 1F). Electrical wires  123  connect to TE Module  101  and shaft  130 .  
         [0049]    A temperature gradient is produced across TE Module  101  by hot fluid  105  heating heat exchanger  102  and cool fluid  107 , cooling heat exchanger  103 . Hot fluid  105  cools and exits and cool fluid  107  is heated and exits. The movement of hot fluid  105  is created by the rotation of heat exchanger  102  componentry which act as vanes of a blower or radial fan. Motor rotor  110  and motor driver  140  produce the rotation. Fluid flow is guided by the outer housings and the insulation.  
         [0050]    [0050]FIG. 1E shows a cross section of TE Module  101  and heat exchangers  102 ,  103 . Heat exchangers  102 ,  103  are shown as folded fins as is known to the art, but may be of any other suitable heat exchanger design, as an example, any advantageous designs found in Kays, William M., and London, Alexander L.,  Compact Heat Exchangers,  3 rd Edition,  1984, McGraw-Hill, Inc. Heat pipes and any other technology may be incorporated to enhance heat transfer.  
         [0051]    [0051]FIG. 1F illustrates additional details of an embodiment of a slip ring assembly for transferring the electric power created TE Module  101  to external systems. The assembly consists of wires  123  in insulation  109 , one of which is electrically connected to inner shaft  119 , and a second to outer shaft  117 . Electrical insulation  142  mechanically connects inner and outer shafts  117 ,  119 . Advantageously, outer shaft  119  is mechanically connected to motor rotor  110  and bearing  144 . Slip ring contact  118  is electrically connected to inner shaft  119  and slip ring contact  120  is electrically connected to outer shaft  117 .  
         [0052]    [0052]FIG. 1G depicts an alternate configuration of a thermoelectric generator that uses flow and pressure of a working fluid to spin the generator assembly, thus eliminating the need for the electric motor shown in FIGS. 1C and 1D.  
         [0053]    As depicted in FIG. 1G, the TE  101 , heat exchangers  102 ,  103  and related parts comprising the rotatable parts of the thermoelectric generator are as identified in FIG. 1D, except that a fan  150  and insulation  109  are attached to form a rotatable unit. Bearings  152 , shaft  130 , and spokes  116 ,  151  form the suspension for the rotatable parts.  
         [0054]    In operation, working fluid  105  propels fan  150 . Power from the fan spins the rotatable parts. In this embodiment, the rotation acts to draw in cold working fluid  107 , as well as provide other benefits from rotation discussed in the description of FIGS.  2  to  7  and  9 .  
         [0055]    The fan  150  is shown as a separate part. The same function can be achieved by using other designs that have heat exchangers or yet other parts shaped and positioned as to utilize power available in the hotter, colder and/or exhaust fluid streams to cause rotation. For Example, such a system could be used in the exhaust stream of a combustion engine, such as with an automobile. In such an example, what would otherwise simply be waste heat, is converted to electricity, and the exhaust flow spins the rotary thermoelectric assembly.  
         [0056]    Motor rotor  110 , insulators  109 ,  142 , and shafts  117 ,  119  rotate as a unit and are supported by bearing  144 . Slip rings  118 ,  120  transmit the electrical power produced within the rotating unit to an external electrical circuit. The slip rings  118 ,  120  can be of any design known to the art, and the shafts  117 ,  119  can be of any viable configuration that are conductive or contain conductive wires or members. The electrical power transmission parts and configuration can be of any design that conveys power from the rotating unit to external circuitry.  
         [0057]    It should be understood that although FIG. 1 depicts a single rotary assembly, multiple rotary assemblies are also contemplated.  
         [0058]    [0058]FIG. 2A depicts a cross-sectional view of rotor assembly  200  for a thermoelectric power generator of the form illustrated generally in FIG. 1. The rotor assembly  200  consists of a ring-shaped TE Module  201  in good thermal contact with a circular array of outer heat pipes  202  and a circular array of inner heat pipes  203 . A hot side heat exchanger  204  is in good thermal contact with outer heat pipes  202 , and a cold side heat exchanger  205  is in good thermal contact with inner heat pipes  203 . The rotor assembly  200  is generally symmetrical about its axis of rotation  211 .  
         [0059]    In operation, the rotor assembly  200  spins about its axis of rotation  211 . Hot fluid (not shown) is in contact with the hot side heat exchanger  204 , which transfers heat flux to the outer heat pipes  202 , and to the outer surface of the TE Module  201 . A portion of the heat flux is converted to electrical power by the TE Module  201 . The waste heat flux passes through the inner heat pipes  203 , then to the cool side heat exchanger  205  and finally to a cooling fluid (not shown) in contact with the cool side heat exchanger  205 .  
         [0060]    [0060]FIG. 2B presents a more detailed view of a cross-section of rotor assembly  200  through a heat pipe. As in FIG. 2A, the heat pipes  202  and  203  are in thermal contact with TE Module  201 . The TE elements  208  and electrical circuitry  209  complete the TE Module  201 . In one preferred embodiment, the heat pipes  202 ,  203  are comprised of sealed shells  214 ,  215  containing a heat transfer fluid. In operation, while the rotor assembly  200  spins about the axis  211 , the rotational forces push a liquid phase of heat transfer fluid away from the axis of rotation of the particular heat pipes  202 ,  203 . The direction of the outward force induced by rotation is shown by arrow  210 . For example, in the heat pipe  202 , a liquid phase  206  forms an interface  212  with the vapor phase. The hot side heat exchanger  204  is in good thermal contact with the hot side heat pipe shell  214 . Similarly, the cool side heat pipes  203 ,  215 , have heat transfer fluid  207  in a liquid phase and an interface  213  with the vapor phase. The cooler side heat exchanger  205  is in good thermal communication with the cool side heat pipe shells  215 .  
         [0061]    The outward force  210  induced by rotor assembly  200  rotation acts to force the liquid phases  206  and  207  to the positions shown in FIG. 2B. Hot gas (not shown) transfers heat from the outer heat exchanger fins  204  to outer heat pipe shells  214 . The heat flux causes a portion of the liquid phase  206  on the hot side to vaporize. The vapor moves inward in the opposite direction to that indicated by arrow  210 , since it is displaced by denser liquid phase  206 . Vapor phase fluid in heat pipes  202  in contact with the interface of TE Module  201  and hot side heat pipe shells  214  transfers a portion of its heat content to the TE Module  201 , and condenses to the liquid phase. The rotation-induced force drives the dense liquid-phase in the direction indicated by the arrow  210 . The fluid cycle repeats as more heat is absorbed by the hot side heat exchanger  204 , transferred to the outer heat pipe shells  214 , and then to the outer surface of TE Module  201 .  
         [0062]    Similarly, waste heat from the inner side of TE Module  201  causes the liquid phase  207  of the inner heat pipe fluid to boil and be convected inward to the inner portions of the inner heat pipe shells  215 . The cold working fluid (not shown) removes heat from the cooler side heat exchanger  205 , and adjacent portions of cooler side heat pipe shells  215 . This causes condensation of the fluid  207 . The liquid phase is driven by centrifugal force in the direction indicated by the arrow  210 , and accumulates against the TE Module  201  and the inner heat pipe shells  215  interface. This cycle constantly repeats, with the fluid constantly evaporating at one location, condensing at another, and being transported back to the first by centrifugal force.  
         [0063]    The forces produced by the rotor assembly  201  rotation can be several times to thousands of times that of gravity, depending on rotor dimensions and rotational speed. Such centrifugal forces can enhance heat pipe heat transfer, thus allowing the rotor assembly  200  to operate with less heat transfer losses and at higher heat fluxes.  
         [0064]    [0064]FIG. 2C shows a sectional view of the rotor assembly  200  of FIG. 2A viewed along the axis of rotation  211 . The TE Module  201  is in good thermal contact with the outer heat pipes  202  and the inner heat pipes  203 . The heat exchangers  204 , 205 , such as fins as shown, are in good thermal contact with the heat pipes  202 ,  203 .  
         [0065]    [0065]FIG. 2C shows individual heat pipe segments  202 ,  203  and the TE Module  201 . The hot working fluid (not shown) flows through passages  216  between the outer heat exchanger fins  204  and the outer heat pipes  202 . Similarly, the cold working fluid (not shown) flows through the inner passages  217  between the inner heat exchanger fins  205  and the inner heat pipes  203 .  
         [0066]    [0066]FIG. 3 depicts an alternative thermoelectric power generator rotor assembly  300 , in which, working fluids flow in a generally radial direction. The cross section view shows a disk-shaped TE Module  301  in good thermal contact with hot side heat pipes  302  and cold side heat pipes  303 . In good thermal contact with the hot side heat pipes  302  is a heat exchanger  304 , and with the cooler side heat pipes  303  is a cool side heat exchanger  305 . The rotor assembly  300  rotates about and is generally symmetrical about a centerline  310 .  
         [0067]    In operation, the rotor assembly  300  spins about the centerline  310 , driven by a motor such as in FIG. 1. Hot working fluid (not shown) passing generally radially outward between the hot side heat exchanger  304  (fins in this depiction) and the hot side heat pipes  302 , transfers heat to the heat exchanger  304  and the outer heat pipes  302  and then to the TE Module  301 . Similarly, cold working fluid (not shown) passing generally radially outward through the center side heat exchanger  303  and the cooler side heat pipes  305  removes heat convected by the cooler side heat pipes  303  from the TE Module  301 . A portion of the thermal flux passing from the hotter side heat pipes  304  to the TE Module  301  and out through the cooler side heat pipes  305  is converted by TE Module  301  to electric power.  
         [0068]    Rotation of the heat pipes  302 ,  303  (configured as flattened tubular sections in this embodiment) advantageously act as fan blades that pump hot and cold working fluids (not shown) outward. Advantageously, the heat exchangers  304 ,  305  and the heat pipes  302 ,  303  are configured to maximize both heat transfer and fan fluid pumping action. Thus, the rotor assembly  300  functions both as the power generator and working fluid pump.  
         [0069]    [0069]FIG. 3B shows a more detailed, cross-sectional view  311  through a heat pipe of the rotor assembly  300  depicted in FIG. 3A. The TE Module  301  is comprised of TE elements  309  and circuitry  310 . The TE Module  301  is in good thermal contact with heat pipes  302 ,  303 . As with the FIG. 2 configuration, the hotter side heat pipes  302  are comprised of sealed shells  312  with a fluid having a liquid phase  306  and vapor phase, with an interface  314 . Similarly, the cooler side heat pipes  303  are comprised of sealed shells  313 , containing fluid with liquid phase  307  and vapor phase, with an interface  315 . The heat exchanger fins  304 ,  305  are in good thermal communication with the heat pipes  302 ,  303 . An arrow  308  points in the direction of an outward force generated as the rotary assembly rotates about the axis  310 .  
         [0070]    In operation, the outward forces push the liquid phases  306 ,  307  of the heat transfer fluids within the heat pipes  302 ,  303  outward, forming the liquid phases  306 ,  307  and the interfaces  314  and  315 . Heat flux from the hot side working fluid (not shown) flowing past the hot side heat exchanger  304  evaporates portions of the fluid  306 , which condenses at the hotter side heat pipe shells  312  at the TE Module  301  interface. Similarly, a portion of the heat flux passes through the TE Module  301  to its interface with cooler side heat pipe shells  313 , and into the cooler side heat pipe fluid  307 , causing the fluid  307  to boil. The vapor phase condenses on the inner portion of the cool side heat pipe shell  313  as heat is removed by transfer to the cooler side heat exchanger  305 , and to the cooler side working fluid (not shown). This heat transfer process is analogous to that described in more detail in the descriptions of FIGS. 2A, 2B and  2 C.  
         [0071]    [0071]FIG. 4 depicts one side of another rotating power generator  400  in cross-section. A TE Module  401  is connected thermally to a cooler side heat exchanger  402  and a hotter side heat exchanger  403 . In the depicted embodiment, the cooler side heat exchanger  402  has segments of heat pipes  404  and fins  406 . Similarly, hotter side heat exchanger  403  has segments of heat pipes  405  and fins  407 . A cooler working fluid  408 ,  410  is confined to a chamber formed by insulators  416 ,  423 , 424  and a duct  412 . Similarly, a hotter working fluid  414  and  415  is confined by the insulators  423 , 424  and an outer duct  411 . Rotor insulation  416  is connected rigidly to a motor rotor  417 , the inner portion of the exchanger  402 , and thereby to the TE Module  401  and heat exchanger  403 . Wires  420  and a shroud  425  are connected rigidly to the TE Module  401 . Similarly, a fan blade assembly  413  is rigidly attached to the TE Module  401 . A shaft assembly  419  is attached to the motor rotor  417 , and to bearings  418 . A slip ring assembly  421  is in electrical communication to a shaft assembly  419 . The insulators  423  and  424  are configured to form a labyrinth seal  422 . Spokes  409  connect the left most bearing  418  to insulation  424  and to duct  411 .  
         [0072]    The assembly formed by the motor rotor  417 , the insulators  416 , 423 , the heat pipes  402 ,  403 , the TE Module  401 , the fan blades  413 , the wires  420 , the shaft  419  and the shroud  425  rotate as a unit. Rotation of the fan blades  413  provides motive force for the hot and the cold working fluids  408 ,  410 ,  414 ,  415 .  
         [0073]    The hot working fluid  414  enters from the left and transfers thermal energy to the hot side heat exchanger  402  and then, to TE Module  401 . The flow of the hot working fluid  414  is driven by the rotation of the fan blades  413 . Similarly, the cooler working fluid  408  enters from the left and extracts waste thermal energy from the cooler side heat exchanger  403  and the TE Module  401 . The electrical power created passes through the wires  420  and out of the rotating portion through the shaft assembly  419  and the slip ring assembly  421 , as was described in more detail in the discussion of FIG. 1F.  
         [0074]    The heat pipes  402 , 403  are segmented to thermally isolate one portion from another for the purposes taught in U.S. patent application Ser. No. 09/844,818 filed Apr. 27, 2001, entitled Improved Efficiency Thermoelectrics Utilizing Thermal Isolation, which application is incorporated by reference herein. Heat transfer within the heat pipes  402 ,  403  is enhanced by the centrifugal acceleration as discussed above, and thereby, increases efficiency of thermal power transport and the allowable power density at which the system can operate. By utilizing centrifugal force to enhance the heat transfer, the overall device can be more compact and employ thermoelectric materials that advantageously operate at high thermal power densities.  
         [0075]    The seal  422  is representative of any seal configuration that suitably separates hot fluid  414  from cold fluid  408  with a moving to stationary boundary. In some configurations, the pumping power of the fan  413  in combination with the inlet geometry may negate the need for the seal  422 . Alternately, seal  422  may serve the function of providing separation of the hotter and cooler working fluids  408 ,  422  if an external, alternate mechanism (not shown) to fan blades  413  provides the force to pump the working fluids  408 ,  422  through the heat exchangers  402 ,  403 . In such an embodiment, the fan  413  may be omitted or its function supplemented by an alternate fluid pump mechanism.  
         [0076]    [0076]FIG. 5 depicts a power generator configuration in which the heat exchangers act as fan blades. The TE Module and heat exchanger are similar in concept to the configuration depicted in FIG. 3. The rotor assembly  500  consists of TE Modules  501 , cooler fluid heat exchanger  502 , a hotter fluid heat exchanger  503 , insulation  515 , 517 , spokes  508  and a motor rotor  509 , all of which are connected rigidly to one another to form a rigid unit that rotates about a shaft  510 . The cooler fluid heat exchanger  502  has heat pipes in good thermal contact with fins  504 . Similarly, the hotter fluids heat exchanger  503  has heat pipes in good thermal contact with fins  505 . Insulation  515 ,  517  and a duct  507  form a chamber that confines a hotter working fluid  511 , 512 . Similarly, insulation  515 ,  517  and a duct  506  form a chamber, which confines a cooler working fluid  513 ,  514 . A seal  516  is formed in the insulation  515 ,  517  to separate the hotter  511  and the colder working  513  fluids.  
         [0077]    The assembly  500  operates by the motor rotor  509  providing motive force to rotate the heat exchangers  502 ,  503 , which, in turn, creates a pumping action to pull hot and cold fluid through the heat exchangers  502 ,  503  to produce a temperature gradient across the TE Module  501 . Electrical power generated thereby is extracted and transferred to external circuitry by the design shown in FIGS.  1 A- 1 E, or by any other transfer method acceptable in the environment.  
         [0078]    Advantageously, several working fluids may be used within a single assembly. A generator such as that of FIG. 4 may have several sources of hot side working fluids each with a different composition and/or temperature. This condition can arise, for example, with waste electrical power generation systems that have several sources of exhaust gas to be processed with waste heated fluid from a boiler, dryer or the like. Such multiple sources of working fluids may be introduced through wall  411  at a position along the axis of rotation where the hot side working fluid  422  has been cooled to a temperature that when combined with an added working fluid, advantageously generates electrical power. In this circumstance, the heat flux may vary in some of the heat pipes  402 ,  407  and fins  405 ,  409  so that TE Modules  101 , heat pipes  402 ,  207  and fins  405 ,  409  may differ in their construction, size, shape, and/or materials from one section to the next in the direction of fluid flow. Also, insulation and fin structure can be used to separate different fluids. Finally, more than one cold side working fluid  409 ,  410  can be utilized in combination with at least one hot side working fluid.  
         [0079]    The design of FIG. 6 also utilizes heat pipes as described in FIG. 4. The assembly  600  of FIG. 6 utilizes counter-flow as taught in U.S. patent application Ser. No. 09/844,818, which is incorporated by reference herein. FIG. 6 depicts a cross-section of yet another rotary thermoelectric power generator. Advantageously, this embodiment also utilizes thermal isolation. The generator assembly  600  has a rotating assembly formed of a TE Module  601 , pairs of thermally isolated heat exchangers  602 ,  603 , fan assemblies  610 ,  613  with shrouds  607 ,  614 , insulation  615 ,  616 ,  619 ,  620 ,  624 , a motor rotor  617  and a shaft assembly  618 .  
         [0080]    Hotter side working fluid  611 , 612  is confined by insulation  609 ,  615 ,  619 ,  620 ,  621 . Cooler side working fluid  604 , 606  is confined by insulation  609 ,  615 ,  616 ,  619 ,  621 , and a duct  608 . Spokes  605  connect a bearing  622  to the insulation  615 .  
         [0081]    Cooler side working fluid  604  enters from the left, absorbs thermal power from heat exchangers  602 , thereby cooling them, and is pumped radially outward by the centrifugal action of fan blades  610 . The fan blades  610  may or may not contain an inner shroud  607  which can be employed to provide structural support and act as a partial seal to keep hotter working fluid  611  separate from the cooler working fluid  606 , and help guide the cooler working fluid&#39;s  606  flow. The hotter working fluid  611  enters in a radially inward direction, conveys thermal power to hotter side heat exchangers  603  and then is pumped radially outward by the action of the rotating fan blades  613 . The shroud  614  may be employed to add structural rigidity to the fan blades  613 , act as a partial seal to separate cooler working fluid  604  from the exiting hotter working fluid  612 , and help guide the hotter working fluid&#39;s  612  flow.  
         [0082]    [0082]FIG. 7 depicts a cross-section of yet another rotary thermoelectric power generator. The design of FIG. 7 is configured to operate in counter flow. The heat exchangers may or may not contain heat pipes to enhance heat transfer.  
         [0083]    [0083]FIG. 7 depicts a radial flow power generator  700 . A rotating assembly consists of a TE Module  701 , heat exchangers  702 , 703 , with fins  704 ,  705 , insulation  720 , fan blades  723 , a motor rotor  718  and a shaft  719 . Bearings  721  attach the shaft assembly  719  to a non-rotating duct  717  inner support  707 , spokes  722  and a duct  710 . The hotter working fluid  706 , 709  is confined by an inner support  707 , the duct  710 , insulation  720 , the TE Module  701  and an exhaust duct  711 . The cooler working fluid  712 ,  713 ,  714  is confined by exhaust ducts  711 , 716 , insulation  720 . the TE Module  701  and a duct  717 . A seal  715  separates the hotter working fluid  709  from the cooler working fluid  712 .  
         [0084]    The assembly  700  operates using counter-flow of the same general type discussed in the description of FIG. 6. It operates in a generally radial direction with the hot side heat exchanger  702  with its fins  704  acting as rotating fan blades to pump hotter working fluid  706 , 709 . Cooler working fluid  712 ,  713 ,  714  responds to the net effect of a radially outward force produced by heat exchanger heat pipes  703  and fins  704  and a larger radially outward force produced by the rotation of fan blades  723  acting on the cooler side working fluid  713 , 714 . The net effect of the counteracting forces is to cause fluid  712 ,  713 , 714  to flow in the directions shown in FIG. 7. Since, the larger blade force is generated by the position of fan blades  723 , being longer than, and extending radially outward farther than the heat exchangers  703  with its fins  705 . Alternately, any portion of the fluids&#39;  706 ,  709 ,  712 ,  713 ,  714  motion could be generated by external fans or pumps. In such configurations, the fan  723  may be, but need not be, deleted.  
         [0085]    Electrical power is generated and transmitted by methods and design described in FIGS. 1 and 5- 6 , or any other advantageous way.  
         [0086]    [0086]FIG. 8 depicts a power generator that combines radial and axial geometries. The general arrangement  800  has a rotational portion consisting of a TE Module  801 , heat exchangers  802 , 803 , a thermal shunt  804 , insulation  811 , a fan assembly  808  and  809 , a duct  807 , a motor rotor  817  and a shaft assembly  818 . Cooler working fluid  805 , 815  is confined by a shroud  807 , insulation  811 , a fan duct  808 , and a wall  810 . Hotter working fluid  812 , 813  is confined by a shunt  804 , a shroud  807 , insulation  811 ,  816  and a wall  814 . A bearing  819  connects rotating shaft assembly  818  to spokes  806  and wall  810 .  
         [0087]    Operation is similar to that previously described in FIG. 7, except that the cooler working fluid  805  flows through heat exchanger  802  in a generally axial direction. As depicted herein, the thermal shunt  804  and the heat exchangers  802 , 803  may or may not contain heat pipes. Further, the heat exchangers  802 ,  803 , the TE Module  801  and the thermal shunt  804  may or may not be constructed so as to be made up of thermally isolated elements as taught in U.S. patent application Ser. No. 09/844,818, entitled Improved Thermoelectrics Utilizing Thermal Isolation, filed Apr. 27, 2001, which patent application is incorporated by reference herein.  
         [0088]    [0088]FIG. 9 depicts an integrated TE Module and heat exchanger. An assembly  900  is a segment of a ring-shaped array of TE Modules  901  with a center of rotation  909  a heat exchanger  902  with fins  904 , heat exchanger  903  with fins  905  and thermal insulation  908 . Gaps  906 ,  907  electrically isolate sections of the fins  904 ,  905  that are connected to the individual heat exchanger parts  902 ,  903 . When operating, one heat exchanger  903 , for example, is cooled and the other heat exchanger  902  is heated creating a thermal gradient across TE Modules  901 . Electrical power is produced by the resultant heat flow.  
         [0089]    In this configuration, the TE Modules  901  may be individual TE elements  901  with a current  910  flowing in a generally circular direction around the ring of which assembly  900  is a portion. In a portion where the TE Modules  901  are individual thermoelectric elements, for the current  910  to flow as shown, the elements  901  are alternately of N-and P-type. Advantageously, heat exchangers  902 ,  903  are electrically conductive in that portion between the adjacent TE elements  901 . If the fins  904 ,  905  are electrically conductive and in electric contact with heat exchangers  902 , 903 , adjacent fins must be electrically isolated from on another as indicated by gaps  906 ,  907 . Electric power can be extracted by breaking the circular current flow at one or more locations and connecting, at the breaks, to electrical circuitry as discussed in FIG. 7.  
         [0090]    Alternately, groups of elements can be between adjacent heat exchangers  903 ,  902 , thus forming TE Modules  901 . Such TE Modules  901  can be connected electrically in series and/or parallel and may have internal provisions for electrical isolation so that gaps  906 ,  907  are not needed. Thermal isolation between hot and cold sides may be maintained by insulation  1008 .  
         [0091]    If the heat exchangers  902 , 903  contain heat pipes, advantageously, working fluids cool the inner heat exchangers  903  and heat the outer heat exchangers  902 .  
         [0092]    [0092]FIG. 10 illustrates a block diagram of a thermoelectric power generator system  1000 . As illustrated, the system has a hotter working fluid source  1002 , a colder working fluid source  1004 , a generator assembly  1006 , exhaust fluid outputs  1008 , and electrical power output  1010 . The generator assembly  1006  is configured with any of the embodiments disclosed above, or any similar embodiment using the principals taught herein. A source of hotter fluid  1002  provide a heat source for the generator assembly  1006 . A source of colder fluid  1004  provide a source of working fluid sufficiently cooler in temperature to create an advantageous temperature gradient across the thermoelectric in the generator assembly  1006 . The waste working fluid exits the generator assembly at an output  1008 . Electrical power from the generator assembly  1006  is provided at a power output  1010 . This system  1000  is merely a generally exemplary system, and is not restrictive of the manner in which the generator assemblies of the present invention would be incorporated into a power generation system.  
         [0093]    The individual teachings in this application may be combined in any advantageous way. Such combinations are part of this invention. Similarly, the teachings of U.S. application Ser. No. 09/844,818 entitled Improved Efficiency Thermoelectrics Utilizing Thermal Isolation, and U.S. application Ser. No. 09/971,539, entitled Thermoelectric Heat Exchanger related to rotary heat exchangers can be used in combination with this application to create variations on the teachings herein, and are part of this invention. For example, the heat exchangers of the hot and/or cold sides, in one embodiment, are configured in portions that are substantially thermally isolated from other portions of the heat exchanger. Similarly, portions of the thermoelectric module, in one embodiment, are thermally isolation from other portions of the thermoelectric module.  
         [0094]    Accordingly, the inventions are not limited to any particular embodiment, or specific disclosure. Rather, the inventions are defined by the appended claims, in which terms are presented to have their ordinary and customary meaning.