Abstract:
A heating, ventilating and air conditioning (HVAC) system for a hybrid vehicle is disclosed, the HVAC system including at least one thermoelectric device for providing supplemental heating and cooling for air supplied to a passenger compartment of the vehicle to maximize an efficiency of operation of the hybrid vehicle during operation of the HVAC system.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a heating, ventilating and air conditioning (HVAC) system for a vehicle and more particularly to a HVAC system for a hybrid vehicle, the HVAC system including at least one thermoelectric device for providing supplemental heating and cooling for air supplied to a passenger compartment of the vehicle. 
       BACKGROUND OF THE INVENTION 
       [0002]    A passenger compartment of a vehicle is typically heated and cooled by a heating, ventilating, and air conditioning (HVAC) system. The HVAC system directs a flow of air through a heat exchanger to heat or cool the air prior to flowing into the passenger compartment. In the heat exchanger, energy is transferred between the air and a coolant such as a water-glycol coolant, for example. The air is normally supplied from ambient air or a mixture of air re-circulated from the passenger compartment and ambient air. Energy for heating and cooling of the passenger compartment of the vehicle is typically supplied from a fuel fed engine such as an internal combustion engine, for example. 
         [0003]    In a hybrid vehicle, both a fuel fed engine and an electric motor are used to power a drive system for the vehicle. Thus, at times the fuel fed engine may be operating, the electric motor may be operating, and both the fuel fed engine and the electric motor may be operating. Therefore, the HVAC system in the hybrid vehicle must be capable of heating and cooling air during each of these operating modes. Examples of such systems are shown and described in commonly owned U.S. patent application Ser. No. 11/101,871 filed Apr. 8, 2005, hereby incorporated herein by reference in its entirety, and U.S. patent application Ser. No. 11/184,447 filed Jul. 19, 2005, hereby incorporated herein by reference in its entirety. If the fuel fed engine must be operating in order to operate the HVAC system in the hybrid vehicle, an efficiency thereof is reduced. 
         [0004]    It would be desirable to produce a heating, ventilating, and air conditioning system for a hybrid vehicle, wherein an efficiency of operation of the hybrid vehicle during operation of the HVAC system is maximized. 
       SUMMARY OF THE INVENTION 
       [0005]    Consistent and consonant with the present invention, a heating, ventilating, and air conditioning system for a hybrid vehicle, wherein an efficiency of operation of the hybrid vehicle during operation of the HVAC system is maximized, has surprisingly been discovered. 
         [0006]    In one embodiment, the heating, ventilating, and air conditioning system for a hybrid vehicle comprises a first fluid circuit including a first conduit for conveying a first fluid therein, the first circuit in thermal communication with an electric side of the hybrid vehicle; a second fluid circuit including a second conduit for conveying the first fluid therein, the second circuit in thermal communication with a fuel fed side of the hybrid vehicle; a first thermoelectric device having a first heat transfer surface and a second heat transfer surface, the first heat transfer surface in thermal communication with at least one of the first circuit and the second circuit, the second heat transfer surface adapted to be in thermal communication with an air stream; and a first heat exchanger disposed in the air stream and in thermal communication with the second fluid circuit, wherein the first circuit, the second circuit, the first thermoelectric device, and the first heat exchanger cooperate to condition the air stream. 
         [0007]    In another embodiment, the heating, ventilating, and air conditioning system for a hybrid vehicle comprises a first conduit forming a first circuit for conveying a first fluid therein; a second conduit forming a second circuit for conveying the first fluid therein; a third conduit for conveying a second fluid therein; a first thermoelectric device having a first heat transfer surface and a second heat transfer surface, the first heat transfer surface in thermal communication with one of the first conduit and the second conduit, the second heat transfer surface in thermal communication with the third conduit; a first heat exchanger disposed in an air stream and in thermal communication with the second conduit; and a second heat exchanger disposed in the air stream downstream of the first heat exchanger and in thermal communication with the third conduit, wherein the first conduit, the second conduit, the third conduit, the first thermoelectric device, the first heat exchanger, and the second heat exchanger cooperate to condition the air stream. 
         [0008]    In another embodiment, the heating, ventilating, and air conditioning system for a hybrid vehicle comprises a first conduit for conveying a first fluid; a second conduit for conveying the first fluid; a third conduit for conveying a second fluid; a first thermoelectric device having a first heat transfer surface and a second heat transfer surface, the first heat transfer surface of the first thermoelectric device in thermal communication with one of the first conduit and the second conduit, the second heat transfer surface of the first thermoelectric device in thermal communication with the third conduit; a first heat exchanger disposed in an air stream and in thermal communication with the second conduit, the first heat exchanger providing a selective heating of the air stream; a second heat exchanger disposed in the air stream downstream of the first heat exchanger and in thermal communication with the third conduit, the second heat exchanger providing selective heating and cooling of the air stream; and a third heat exchanger disposed in the air stream downstream of the second heat exchanger adapted to be in thermal communication with a source of heat to provide selective heating of the air stream, wherein the first conduit, the second conduit, the third conduit, the first thermoelectric device, the first heat exchanger, the second heat exchanger, and the third heat exchanger cooperate to condition the air stream. 
     
     
       DESCRIPTION OF THE DRAWINGS 
         [0009]    The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which: 
           [0010]      FIG. 1  is a schematic flow diagram of a heating, ventilating, and air conditioning (HVAC) system according to an embodiment of the invention; 
           [0011]      FIG. 2  is a schematic flow diagram of a HVAC system according to another embodiment of the invention; 
           [0012]      FIG. 3  is a schematic flow diagram of a HVAC system according to another embodiment of the invention; 
           [0013]      FIG. 4  is a schematic flow diagram of a HVAC system according to another embodiment of the invention; 
           [0014]      FIG. 5  is a schematic flow diagram of a HVAC system according to another embodiment of the invention; 
           [0015]      FIG. 6  is a schematic flow diagram of a HVAC system according to another embodiment of the invention; 
           [0016]      FIG. 7  is a schematic flow diagram of a HVAC system according to another embodiment of the invention; and 
           [0017]      FIG. 8  is a schematic flow diagram of a HVAC system according to another embodiment of the invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0018]    The following detailed description and appended drawings describe and illustrate various exemplary embodiments of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner. In respect of the methods disclosed, the steps presented are exemplary in nature, and thus, the order of the steps is not necessary or critical. 
         [0019]      FIG. 1  shows a heating ventilating, and air conditioning (HVAC) system  10  for supplying conditioned air to a passenger compartment of a vehicle according to an embodiment of the invention. The system  10  includes a first fluid circuit  12  and a second fluid circuit  14 . In the embodiment shown, the first circuit  12  communicates with components of an electric side of a hybrid vehicle (not shown) and the second circuit  14  communicates with components of a fuel fed side of the hybrid vehicle. As used herein, electric side is meant to include components relating to an electric motor for powering the hybrid vehicle such as a battery compartment, for example. Fuel fed side is meant to include components relating to a fuel fed engine for powering the hybrid vehicle such as an internal combustion engine, for example. A first fluid (not shown) is circulated in the first circuit  12  and the second circuit  14  and can be any conventional fluid such as air or a coolant such as a water-glycol coolant, for example. 
         [0020]    The first circuit  12  includes a first conduit  16  for conveying the first fluid through the first circuit  12 . A pump  18  is disposed in the first conduit  16  to circulate the first fluid therethrough. A pump as used herein is meant to include any conventional pump such as a centrifugal pump, for example, a fan, and the like. The first conduit  16  includes a heat exchanger  20  disposed therein. The heat exchanger  20  can be any conventional heat exchanger such as a low temperature core, for example. The first fluid is also circulated through a battery compartment or other source of heat  22  from the electric side of the hybrid vehicle to remove heat therefrom. In the embodiment shown, the battery compartment  22  is disposed in parallel with the heat exchanger  20 . However, it is understood that other configurations can be used as desired such as in series or a separate conduit, for example. A flow valve  24  and a diverter valve  26  are also disposed in the first conduit  16 . It is understood that more or fewer valves may be used as desired to control flow of the first fluid through the first conduit  16 . The flow valve  24  can be any conventional type such as a gate valve, a ball valve, a flap type valve, and the like, for example. The diverter valve  26  can be any conventional diverter valve such as a three way valve used to selectively permit flow between conduit branches, for example. 
         [0021]    Crossover conduits  28 ,  30  are provided between the first circuit  12  and the second circuit  14 . Flow valves  32 ,  34  are provided in respective crossover conduits  28 ,  30  to selectively permit flow of the first fluid therethrough. A pump  36  is also provided in the crossover conduit  28  to assist with circulation of the first fluid, if necessary. 
         [0022]    A second conduit  38  is included in the second circuit  14 . The second conduit  38  is in fluid communication with an engine  40  of the hybrid vehicle to circulate the first fluid therethrough and remove heat therefrom. A heat exchanger  42  is disposed in the second conduit  38  downstream of the engine  40 . The heat exchanger  42  can be any conventional heat exchanger such as a radiator for the vehicle, for example. A first bypass conduit  44  is provided to permit bypassing of the heat exchanger  42  and a second bypass conduit  46  is provided to create a recirculation circuit. A diverter valve  48  selectively permits flow between the heat exchanger  42  and the first bypass conduit  44 . Selective flow for the second bypass conduit  46  is facilitated by a diverter valve  50 . It is understood that more or fewer valves may be used as desired to control flow of the first fluid through the second conduit  38 . A pump  52  is disposed in the second conduit  38  to circulate the first fluid therethrough. 
         [0023]    A first thermoelectric device (TED)  54  is disposed adjacent the first conduit  16  and between the crossover conduits  28 ,  30 . The first TED  54  includes a first heat transfer surface  55  and a second heat transfer surface  56 . The first heat transfer surface  55  is in thermal communication with the first conduit  16  of the first circuit  12 . The first TED  54  is in electrical communication with a control system (not shown). The control system controls an electric current sent to the first TED  54 . When the current is delivered in one direction, one of the first heat transfer surface  55  and the second heat transfer surface  56  generates thermal energy or heat and the other of the first heat transfer surface  55  and the second heat transfer surface  56  absorbs thermal energy or heat. When the current is reversed, the one of the first heat transfer surface  55  and the second heat transfer surface  56  which was generating heat now absorbs heat and the other of the first heat transfer surface  55  and the second heat transfer surface  56  now generates heat. Additionally, when the current is increased, a heating and cooling capacity of the TED is increased. Likewise, when the current is decreased, the heating and cooling capacity of the TED is decreased. 
         [0024]    The TED  54  may be any conventional device such as: those produced by Marlow Industries, Inc. of Dallas, Tex.; the thermoelectric systems described in U.S. Pat. No. 6,539,725 to Bell; a quantum tunneling converter; a Peltier device; a thermoionic module; a magneto caloric module; an acoustic heating mechanism; a solid state heat pumping device; and the like; for example; or any combination of the devices listed above. Although a single thermoelectric device is shown, it is understood that additional thermoelectric devices can be used, as desired. 
         [0025]    A third conduit  57  is in thermal communication with the second heat transfer surface  56  of the first TED  54 . The third conduit  57  conveys a second fluid (not shown). The second fluid can be any conventional fluid such as air or a coolant such as a water-glycol coolant, for example. A pump  58  is disposed in the third conduit  57  to circulate the second fluid therethrough. 
         [0026]    An air conduit  60  in fluid communication with a source of air (not shown) is provided to supply the conditioned air to the passenger compartment of the vehicle. The air conduit  60  includes a first heat exchanger  62 , a second heat exchanger  64 , and a third heat exchanger  66  disposed therein. The heat exchangers  62 ,  64 ,  66  can be any conventional type of heat exchanger. 
         [0027]    The first heat exchanger  62  and the third heat exchanger  66  are in fluid communication with the second circuit  14 . A diverter valve  68  is disposed in a supply side of the second conduit  38  to selectively control flow of the first fluid to the first heat exchanger  62  and the third heat exchanger  66 . A diverter valve  70  is disposed in the second conduit  38  on a return side thereof to selectively control flow of the first fluid from the first heat exchanger  62  and the third heat exchanger  66 . 
         [0028]    The second heat exchanger  64  is in fluid communication with the third conduit  57 . The third conduit  57  circulates the second fluid between the first TED  54  and the second heat exchanger  64 . 
         [0029]    In operation, the system  10  conditions the air flowing from the source of air for supply of the conditioned air to the passenger compartment of the vehicle. A flow direction of the air from the source of air is indicated by the arrow in the air conduit  60 . The system  10  can operate in a heating mode, a demisting mode, and a cooling mode. 
         [0030]    In a first heating mode where the engine  40  is operating and the electric motor is not operating, the first heat exchanger  62  and the second heat exchanger  64  transfer heat into the air stream, and the third heat exchanger  66  is idle. Thus, the diverter valves  68 ,  70  are positioned to militate against flow of the first fluid to the third heat exchanger  66  and permit flow to the first heat exchanger  62 . The pump  52  of the second circuit  14  is operating to circulate the first fluid through the second conduit  38 . Heat is transferred into the first fluid by the engine  40 . 
         [0031]    The diverter valve  48  is positioned to militate against flow through the heat exchanger  42  and permit flow through the first bypass conduit  44 . Thus, heat is not removed from the first fluid in the heat exchanger  42  and the first fluid flows through the first bypass conduit  44 . The diverter valve  50  is in a position to militate against flow of the first fluid through the second bypass conduit  46 . Therefore, the first fluid flows through the second conduit  38  to the first heat exchanger  62  where heat is transferred from the first fluid to the air flowing in the air conduit  60 . 
         [0032]    The pump  18  of the first circuit  12  is not operating to circulate the first fluid through the first conduit  16 . In order to supply the first fluid to the first TED  54 , the pump  36  is operating and the valves  32 ,  34  of the crossover conduits  28 ,  30  are open to permit flow therethrough. A portion of the flow of the first fluid in the second conduit  38  is directed through the crossover conduit  28  and into thermal communication with the first heat transfer surface  55  of the first TED  54 . The controller causes the current to the first TED  54  to flow to cause the first heat transfer surface  55  to absorb heat and remove heat from the first fluid. The first fluid then flows through the crossover conduit  30  to re-enter the second conduit  38  and flow to the first heat exchanger  62 . 
         [0033]    The pump  58  is operating to circulate the second fluid through the third conduit  57 . The second fluid is in thermal communication with the second heat transfer surface  56  of the first TED  54 . The second heat transfer surface  56  generates heat which is transferred to the second fluid. Thus, the second fluid flows to the second heat exchanger  64  where heat is transferred from the second fluid to the air flowing in the air conduit  60 . Therefore, heated air is delivered to the passenger compartment of the vehicle from the first heat exchanger  62  and the second heat exchanger  64 . It is understood that this mode can be used with only the first heat exchanger  62  transferring heat into the air stream and the second heat exchanger  64  idle. 
         [0034]    In a second heating mode where the engine  40  is operating and the electric motor is operating, the first heat exchanger  62  and the second heat exchanger  64  transfer heat into the air stream, and the third heat exchanger  66  is idle. Thus, the diverter valves  68 ,  70  are positioned to militate against flow of the first fluid to the third heat exchanger  66  and permit flow to the first heat exchanger  62 . The pump  52  of the second circuit  14  is operating to circulate the first fluid through the second conduit  38 . Heat is transferred into the first fluid by the engine  40 . 
         [0035]    The diverter valve  48  is positioned to militate against flow through the heat exchanger  42  and permit flow through the first bypass conduit  44 . Thus, heat is not removed from the first fluid in the heat exchanger  42  and the first fluid flows through the first bypass conduit  44 . The diverter valve  50  is in a position to militate against flow of the first fluid through the second bypass conduit  46 . Therefore, the first fluid flows through the second conduit  38  to the first heat exchanger  62  where heat is transferred from the first fluid to the air flowing in the air conduit  60 . 
         [0036]    The pump  18  of the first circuit  12  is operating to circulate the first fluid through the first conduit  16  to supply the first fluid to the first TED  54 . The pump  36  is not operating and the valves  32 ,  34  of the crossover conduits  28 ,  30  are closed to militate against flow therethrough. The first fluid flows through the battery compartment  22  where heat is transferred into the first fluid, then through the first conduit  16 , and into thermal communication with the first heat transfer surface  55  of the first TED  54 . The diverter valve  26  is positioned to militate against flow through the heat exchanger  20  and permit flow to the battery compartment  22 . Thus, heat is not removed from the first fluid in the heat exchanger  20 . The controller causes the current to the first TED  54  to flow to cause the first heat transfer surface  55  to absorb heat and remove heat from the first fluid. The first fluid then returns to the pump  18  for recirculation. 
         [0037]    The pump  58  is operating to circulate the second fluid through the third conduit  57 . The second fluid is in thermal communication with the second heat transfer surface  56  of the first TED  54 . The second heat transfer surface  56  generates heat which is transferred to the second fluid. Thus, the second fluid flows to the second heat exchanger  64  where heat is transferred from the second fluid to the air flowing in the air conduit  60 . Therefore, heated air is delivered to the passenger compartment of the vehicle from the first heat exchanger  62  and the second heat exchanger  64 . 
         [0038]    In a third heating mode where the engine  40  is not operating and the electric motor is operating, the second heat exchanger  64  transfers heat into the air stream, and the first heat exchanger  62  and the third heat exchanger  66  are idle. Initially, it is presumed that the engine  40  was previously running and requires cooling. The pump  52  of the second circuit  14  is operating to circulate the first fluid through the second conduit  38 . Heat is transferred into the first fluid by the engine  40 . 
         [0039]    The diverter valve  48  is positioned to militate against flow through the first bypass conduit  44  and permit flow through the heat exchanger  42 . Thus, heat is removed from the first fluid in the heat exchanger  42 . The diverter valve  50  is in a position to permit flow of the first fluid through the second bypass conduit  46  and militate against flow through the second conduit  38  to the first heat exchanger  62  and the third heat exchanger  66 . Once the engine  40  has sufficiently cooled, the pump  52  can be switched to the off position until the engine  40  requires additional cooling. 
         [0040]    The pump  18  of the first circuit  12  is operating to circulate the first fluid through the first conduit  16  to supply the first fluid to the first TED  54 . The pump  36  is not operating and the valves  32 ,  34  of the crossover conduits  28 ,  30  are closed to militate against flow therethrough. The first fluid flows through the battery compartment  22  where heat is transferred into the first fluid, then through the first conduit  16 , and into thermal communication with the first heat transfer surface  55  of the first TED  54 . The diverter valve  26  is positioned to militate against flow through the heat exchanger  20  and permit flow to the battery compartment  22 . Thus, heat is not removed from the first fluid in the heat exchanger  20 . The controller causes the current to the first TED  54  to flow to cause the first heat transfer surface  55  to absorb heat and remove heat from the first fluid. The first fluid then returns to the pump  18  for recirculation. 
         [0041]    The pump  58  is operating to circulate the second fluid through the third conduit  57 . The second fluid is in thermal communication with the second heat transfer surface  56  of the first TED  54 . The second heat transfer surface  56  generates heat which is transferred to the second fluid. Thus, the second fluid flows to the second heat exchanger  64  where heat is transferred from the second fluid to the air flowing in the air conduit  60 . Therefore, heated air is delivered to the passenger compartment of the vehicle from the second heat exchanger  64 . It is also understood that this mode can be used when both the engine  40  and the electric motor are operating, but where the amount heat required to be delivered to the passenger compartment of the vehicle is low. 
         [0042]    In a demisting mode, the engine  40  is operating and the electric motor is operating. The first heat exchanger  62  is idle, the second heat exchanger  64  removes heat from the air stream, and the third heat exchanger  66  transfers heat into the air stream. It is understood that the engine  40  may have also been previously running and has residual heat stored therein. The diverter valves  68 ,  70  are positioned to militate against flow of the first fluid to the first heat exchanger  62  and permit flow to the third heat exchanger  66 . The pump  52  of the second circuit  14  is operating to circulate the first fluid through the second conduit  38 . Heat is transferred into the first fluid by the engine  40 . 
         [0043]    The diverter valve  48  is positioned to militate against flow through the heat exchanger  42  and permit flow through the first bypass conduit  44 . Thus, heat is not removed from the first fluid in the heat exchanger  42  and the first fluid flows through the first bypass conduit  44 . The diverter valve  50  is in a position to militate against flow of the first fluid through the second bypass conduit  46 . Therefore, the first fluid flows through the second conduit  38  to the third heat exchanger  66  where heat is transferred from the first fluid to the air flowing in the air conduit  60 . 
         [0044]    The pump  18  of the first circuit  12  is operating to circulate the first fluid through the first conduit  16  to supply the first fluid to the first TED  54 . The pump  36  is not operating and the valves  32 ,  34  of the crossover conduits  28 ,  30  are closed to militate against flow therethrough. The diverter valve  26  is positioned to permit flow through the heat exchanger  20  and militate against flow to the battery compartment  22 . Thus, heat is removed from the first fluid in the heat exchanger  20 . The controller causes the current to the first TED  54  to flow to cause the first heat transfer surface  55  to generate heat which is absorbed by the first fluid. The first fluid then returns to the pump  18  for recirculation. 
         [0045]    The pump  58  is operating to circulate the second fluid through the third conduit  57 . The second fluid is in thermal communication with the second heat transfer surface  56  of the first TED  54 . The second heat transfer surface  56  removes heat from the second fluid. Thus, the second fluid flows to the second heat exchanger  64  where heat is transferred from the air flowing in the air conduit  60  to the second fluid. Therefore, air is cooled in the second heat exchanger  64 , heated by the third heat exchanger  66 , and delivered to the passenger compartment of the vehicle for demisting. By initially cooling the air, moisture is caused to be removed from the air by condensation. 
         [0046]    In a cooling mode, where the engine  40  is not operating and the electric motor is operating, the second heat exchanger  64  removes heat from the air stream, and the first heat exchanger  62  and the third heat exchanger  66  are idle. Initially, it is presumed that the engine  40  was previously running and requires cooling. The pump  52  of the second circuit  14  is operating to circulate the first fluid through the second conduit  38 . Heat is transferred into the first fluid by the engine  40 . 
         [0047]    The diverter valve  48  is positioned to militate against flow through the first bypass conduit  44  and permit flow through the heat exchanger  42 . Thus, heat is removed from the first fluid in the heat exchanger  42 . The diverter valve  50  is in a position to permit flow of the first fluid through the second bypass conduit  46  and militate against flow through the second conduit  38  to the first heat exchanger  62  and the third heat exchanger  66 . Once the engine  40  has sufficiently cooled, the pump  52  can be switched to the off position until the engine  40  requires additional cooling. 
         [0048]    The pump  18  of the first circuit  12  is operating to circulate the first fluid through the first conduit  16  to supply the first fluid to the first TED  54 . The pump  36  is not operating and the valves  32 ,  34  of the crossover conduits  28 ,  30  are closed to militate against flow therethrough. The diverter valve  26  is positioned to permit flow through the heat exchanger  20  and militate against flow to the battery compartment  22 . Thus, heat is removed from the first fluid in the heat exchanger  20 . The controller causes the current to the first TED  54  to flow to cause the first heat transfer surface  55  to generate heat which is absorbed by the first fluid. The first fluid then returns to the pump  18  for recirculation. 
         [0049]    The pump  58  is operating to circulate the second fluid through the third conduit  57 . The second fluid is in thermal communication with the second heat transfer surface  56  of the first TED  54 . The second heat transfer surface  56  removes heat from the second fluid. Thus, the second fluid flows to the second heat exchanger  64  where heat is transferred from the air flowing in the air conduit  60  to the second fluid. Therefore, air is cooled in the second heat exchanger  64  and delivered to the passenger compartment of the vehicle. 
         [0050]      FIG. 2  shows a heating ventilating, and air conditioning (HVAC) system  100  for supplying conditioned air to a passenger compartment of a vehicle according to another embodiment of the invention. Structure included from  FIG. 1  has the same reference numeral for clarity and a description thereof is not repeated. 
         [0051]    In the embodiment shown, a second thermoelectric device (TED)  102  is disposed adjacent the first conduit  16  and the first TED  54 , and between the crossover conduits  28 ,  30 . The second TED  102  includes a first heat transfer surface  104  and a second heat transfer surface  106 . The first heat transfer surface  104  is in thermal communication with the first conduit  16  of the first circuit  12 . The second TED  102  is in electrical communication with a control system (not shown). The control system controls an electric current sent to the second TED  102  in the same way as described for the first TED  54 . The second thermoelectric device  102  may be any conventional device such as those listed for the first TED  54 . Although a single thermoelectric device is shown, it is understood that additional thermoelectric devices can be used, as desired. 
         [0052]    A fourth conduit  108  is in thermal communication with the second heat transfer surface  106  of the second TED  102 . The fourth conduit  108  conveys a third fluid (not shown). The third fluid can be any conventional fluid such as air or a coolant such as a water-glycol coolant, for example. A pump  110  is disposed in the fourth conduit  108  to circulate the third fluid therethrough. 
         [0053]    The first heat exchanger  62  is in fluid communication with the second circuit  14  and the third heat exchanger  66  is in fluid communication with the fourth conduit  108 . The fourth conduit  108  circulates the third fluid between the second TED  102  and the third heat exchanger  66 . 
         [0054]    In operation, the system  100  conditions the air flowing from the source of air for supply of the conditioned air to the passenger compartment of the vehicle. A flow direction of the air from the source of air is indicated by the arrow in the air conduit  60 . Similar to the operation described for the system  10 , the system  100  can operate in a heating mode, a demisting mode, and a cooling mode. 
         [0055]    In a first heating mode where the engine  40  is operating and the electric motor is not operating, the first heat exchanger  62 , the second heat exchanger  64 , and the third heat exchanger  66  transfer heat into the air stream. The pump  52  of the second circuit  14  is operating to circulate the first fluid through the second conduit  38 . Heat is transferred into the first fluid by the engine  40 . 
         [0056]    The diverter valve  48  is positioned to militate against flow through the heat exchanger  42  and permit flow through the first bypass conduit  44 . Thus, heat is not removed from the first fluid in the heat exchanger  42  and the first fluid flows through the first bypass conduit  44 . The diverter valve  50  is in a position to militate against flow of the first fluid through the second bypass conduit  46 . Therefore, the first fluid flows through the second conduit  38  to the first heat exchanger  62  where heat is transferred from the first fluid to the air flowing in the air conduit  60 . 
         [0057]    The pump  18  of the first circuit  12  is not operating to circulate the first fluid through the first conduit  16 . In order to supply the first fluid to the first TED  54  and the second TED  102 , the pump  36  is operating and the valves  32 ,  34  of the crossover conduits  28 ,  30  are open to permit flow therethrough. A portion of the flow of the first fluid in the second conduit  38  is directed through the crossover conduit  28  and into thermal communication with the first heat transfer surface  55  of the first TED  54  and the first heat transfer surface  104  of the second TED  102 . The controller causes the current to the first TED  54  and the second TED  102  to flow to cause the first heat transfer surface  55  and the first heat transfer surface  104  to absorb heat and remove heat from the first fluid. The first fluid then flows through the crossover conduit  30  to re-enter the second conduit  38  and flow to the first heat exchanger  62 . 
         [0058]    The pump  58  is operating to circulate the second fluid through the third conduit  57 . The second fluid is in thermal communication with the second heat transfer surface  56  of the first TED  54 . The second heat transfer surface  56  generates heat which is transferred to the second fluid. Thus, the second fluid flows to the second heat exchanger  64  where heat is transferred from the second fluid to the air flowing in the air conduit  60 . 
         [0059]    The pump  110  is operating to circulate the third fluid through the fourth conduit  108 . The third fluid is in thermal communication with the second heat transfer surface  106  of the second TED  102 . The second heat transfer surface  106  generates heat which is transferred to the third fluid. Thus, the third fluid flows to the third heat exchanger  66  where heat is transferred from the third fluid to the air flowing in the air conduit  60 . Therefore, heated air is delivered to the passenger compartment of the vehicle from the first heat exchanger  62 , the second heat exchanger  64 , and the third heat exchanger  66 . It is understood that this mode can be used with the first heat exchanger  62  and the second heat exchanger  64  transferring heat into the air stream, and the third heat exchanger  66  idle. It is also understood that this mode can be used with only the first heat exchanger  62  transferring heat into the air stream, and the second heat exchanger  64  and the third heat exchanger  66  idle. 
         [0060]    In a second heating mode where the engine  40  is operating and the electric motor is operating, the first heat exchanger  62 , the second heat exchanger  64 , and the third heat exchanger  66  transfer heat into the air stream. The pump  52  of the second circuit  14  is operating to circulate the first fluid through the second conduit  38 . Heat is transferred into the first fluid by the engine  40 . 
         [0061]    The diverter valve  48  is positioned to militate against flow through the heat exchanger  42  and permit flow through the first bypass conduit  44 . Thus, heat is not removed from the first fluid in the heat exchanger  42  and the first fluid flows through the first bypass conduit  44 . The diverter valve  50  is in a position to militate against flow of the first fluid through the second bypass conduit  46 . Therefore, the first fluid flows through the second conduit  38  to the first heat exchanger  62  where heat is transferred from the first fluid to the air flowing in the air conduit  60 . 
         [0062]    The pump  18  of the first circuit  12  is operating to circulate the first fluid through the first conduit  16  to supply the first fluid to the first TED  54  and the second TED  102 . The pump  36  is not operating and the valves  32 ,  34  of the crossover conduits  28 ,  30  are closed to militate against flow therethrough. The first fluid flows through the battery compartment  22  where heat is transferred into the first fluid, then through the first conduit  16 , and into thermal communication with the first heat transfer surface  55  of the first TED  54  and the first heat transfer surface  104  of the second TED  102 . The diverter valve  26  is positioned to militate against flow through the heat exchanger  20  and permit flow to the battery compartment  22 . Thus, heat is not removed from the first fluid in the heat exchanger  20 . The controller causes the current to the first TED  54  and the second TED  102  to flow to cause the first heat transfer surface  55  and the first heat transfer surface  104  to absorb heat to and remove heat from the first fluid. The first fluid then returns to the pump  18  for recirculation. 
         [0063]    The pump  58  is operating to circulate the second fluid through the third conduit  57 . The second fluid is in thermal communication with the second heat transfer surface  56  of the first TED  54 . The second heat transfer surface  56  generates heat which is transferred to the second fluid. Thus, the second fluid flows to the second heat exchanger  64  where heat is transferred from the second fluid to the air flowing in the air conduit  60 . 
         [0064]    The pump  110  is operating to circulate the third fluid through the fourth conduit  108 . The third fluid is in thermal communication with the second heat transfer surface  106  of the second TED  102 . The second heat transfer surface  106  generates heat which is transferred to the third fluid. Thus, the third fluid flows to the third heat exchanger  66  where heat is transferred from the third fluid to the air flowing in the air conduit  60 . Therefore, heated air is delivered to the passenger compartment of the vehicle from the first heat exchanger  62 , the second heat exchanger  64 , and the third heat exchanger  66 . It is understood that this mode can be used with the first heat exchanger  62  and the second heat exchanger  64  transferring heat into the air stream, and the third heat exchanger  66  idle. It is also understood that this mode can be used with only the first heat exchanger  62  transferring heat into the air stream, and the second heat exchanger  64  and the third heat exchanger  66  idle. It is understood that a third heating mode as described above for  FIG. 1  can be used with the first TED  54  and the second heat exchanger  64 , or the first TED  54  and the second heat exchanger  64  and the second TED  102  and the third heat exchanger  66  with the first heat exchanger  62  being idle. 
         [0065]    In a demisting mode, the engine  40  is not operating and the electric motor is operating. The first heat exchanger  62  is idle, the second heat exchanger  64  removes heat from the air stream, and the third heat exchanger  66  transfers heat into the air stream. It is understood that the engine  40  may have also been previously running and has residual heat stored therein, and that the second circuit  14  is operated as described for  FIG. 1  to remove heat from the engine  40 . Additionally, it is understood that the engine  40  could be operating, and that the second circuit  14  is operated as described for  FIG. 1  to remove heat from the engine  40 . 
         [0066]    The pump  18  of the first circuit  12  is operating to circulate the first fluid through the first conduit  16  to supply the first fluid to the first TED  54  and the second TED  102 . The pump  36  is not operating and the valves  32 ,  34  of the crossover conduits  28 ,  30  are closed to militate against flow therethrough. The diverter valve  26  is positioned to permit flow through the heat exchanger  20  and militate against flow to the battery compartment  22 . Thus, heat is removed from the first fluid in the heat exchanger  20 . The controller causes the current in the second TED  102  to flow to cause the first heat transfer surface  104  to absorb heat and remove heat from the first fluid. The controller causes the current to the first TED  54  to flow to cause the first heat transfer surface  55  to generate heat which is absorbed by the first fluid. The first fluid then returns to the pump  18  for recirculation. 
         [0067]    The pump  58  is operating to circulate the second fluid through the third conduit  57 . The second fluid is in thermal communication with the second heat transfer surface  56  of the first TED  54 . The second heat transfer surface  56  removes heat from the second fluid. Thus, the second fluid flows to the second heat exchanger  64  where heat is transferred from the air flowing in the air conduit  60  to the second fluid. 
         [0068]    The pump  110  is operating to circulate the third fluid through the fourth conduit  108 . The third fluid is in thermal communication with the second heat transfer surface  106  of the second TED  102 . The second heat transfer surface  106  generates heat which is absorbed by the third fluid. Thus, the third fluid flows to the third heat exchanger  66  where heat is transferred to the air flowing in the air conduit  60  from the third fluid. 
         [0069]    Therefore, air is cooled in the second heat exchanger  64 , heated by the third heat exchanger  66 , and delivered to the passenger compartment of the vehicle for demisting. By initially cooling the air, moisture is caused to be removed from the air by condensation. 
         [0070]    In a cooling mode, where the engine  40  is not operating and the electric motor is operating, the second heat exchanger  64  and the third heat exchanger  66  remove heat from the air stream, and the first heat exchanger  62  is idle. It is understood that the engine  40  may have also been previously running and has residual heat stored therein, and that the second circuit  14  is operated as described for  FIG. 1  to remove heat from the engine  40 . Additionally, it is understood that the engine  40  could be operating, and that the second circuit  14  is operated as described for  FIG. 1  to remove heat from the engine  40 . 
         [0071]    The pump  18  of the first circuit  12  is operating to circulate the first fluid through the first conduit  16  to supply the first fluid to the first TED  54  and the second TED  102 . The pump  36  is not operating and the valves  32 ,  34  of the crossover conduits  28 ,  30  are closed to militate against flow therethrough. The diverter valve  26  is positioned to permit flow through the heat exchanger  20  and militate against flow to the battery compartment  22 . Thus, heat is removed from the first fluid in the heat exchanger  20 . The controller causes the current to the first TED  54  and the second TED  102  to flow to cause the first heat transfer surface  55  and the first heat transfer surface  104  to generate heat which is absorbed by the first fluid. The first fluid then returns to the pump  18  for recirculation. 
         [0072]    The pump  58  is operating to circulate the second fluid through the third conduit  57 . The second fluid is in thermal communication with the second heat transfer surface  56  of the first TED  54 . The second heat transfer surface  56  removes heat from the first fluid. Thus, the second fluid flows to the second heat exchanger  64  where heat is transferred from the air flowing in the air conduit  60  to the second fluid. 
         [0073]    The pump  110  is operating to circulate the third fluid through the fourth conduit  108 . The third fluid is in thermal communication with the second heat transfer surface  106  of the second TED  102 . The second heat transfer surface  106  removes heat from the third fluid. Thus, the third fluid flows to the third heat exchanger  66  where heat is transferred from the air flowing in the air conduit  60  to the third fluid. Therefore, air is cooled in the second heat exchanger  64  and the third heat exchanger  66 , and delivered to the passenger compartment of the vehicle. It is understood that this mode can be used with one of the second heat exchanger  64  and the third heat exchanger  66  transferring heat from the air stream, and the other of the second heat exchanger  64  and the third heat exchanger  66  idle. 
         [0074]      FIG. 3  shows a heating ventilating, and air conditioning (HVAC) system  120  for supplying conditioned air to a passenger compartment of a vehicle according to another embodiment of the invention. Structure included from  FIGS. 1 and 2  has the same reference numeral for clarity and a description thereof is not repeated. 
         [0075]    In the embodiment shown, the first TED  54  and the second TED  102  include a third conduit  122  in thermal communication with both the second heat transfer surface  56  of the first TED  54  and the second heat transfer surface  106  of the second TED  102 . The third conduit  122  conveys a second fluid (not shown). The second fluid can be any conventional fluid such as air or a coolant such as a water-glycol coolant, for example. A pump  124  is disposed in the third conduit  122  to circulate the second fluid therethrough. 
         [0076]    The first heat exchanger  62  is in fluid communication with the second circuit  14 . The second heat exchanger  64  has an outlet  126  in fluid communication with the first TED  54  and an inlet  128  in fluid communication with the second TED  102 . The third heat exchanger  66  has an outlet  130  in fluid communication with the second TED  102  and an inlet  132  in fluid communication with the first TED  54 . The third conduit  122  circulates the second fluid between the first TED  54 , the third heat exchanger  66 , the second TED  102  and the second heat exchanger  64 . 
         [0077]    In operation, the system  120  conditions the air flowing from the source of air for supply of the conditioned air to the passenger compartment of the vehicle. A flow direction of the air from the source of air is indicated by the arrow in the air conduit  60 . Similar to the operation described for the systems  10 ,  100 , the system  120  can operate in a heating mode, a demisting mode, and a cooling mode. 
         [0078]    In a first heating mode where the engine  40  is operating and the electric motor is not operating, the first heat exchanger  62 , the second heat exchanger  64 , and the third heat exchanger  66  transfer heat into the air stream. The pump  52  of the second circuit  14  is operating to circulate the first fluid through the second conduit  38 . Heat is transferred into the first fluid by the engine  40 . 
         [0079]    The diverter valve  48  is positioned to militate against flow through the heat exchanger  42  and permit flow through the first bypass conduit  44 . Thus, heat is not removed from the first fluid in the heat exchanger  42  and the first fluid flows through the first bypass conduit  44 . The diverter valve  50  is in a position to militate against flow of the first fluid through the second bypass conduit  46 . Therefore, the first fluid flows through the second conduit  38  to the first heat exchanger  62  where heat is transferred from the first fluid to the air flowing in the air conduit  60 . 
         [0080]    The pump  18  of the first circuit  12  is not operating to circulate the first fluid through the first conduit  16 . In order to supply the first fluid to the first TED  54  and the second TED  102 , the pump  36  is operating and the valves  32 ,  34  of the crossover conduits  28 ,  30  are open to permit flow therethrough. A portion of the flow of the first fluid in the second conduit  38  is directed through the crossover conduit  28  and into thermal communication with the first heat transfer surface  55  of the first TED  54  and the first heat transfer surface  104  of the second TED  102 . The controller causes the current to the first TED  54  and the second TED  102  to flow to cause the first heat transfer surface  55  and the first heat transfer surface  104  to absorb heat and remove heat from the first fluid. The first fluid then flows through the crossover conduit  30  to re-enter the second conduit  38  and flow to the first heat exchanger  62 . 
         [0081]    The pump  124  is operating to circulate the second fluid through the third conduit  122 . The second fluid is in thermal communication with the second heat transfer surface  56  of the first TED  54  and the second heat transfer surface  106  of the second TED  102 . The second heat transfer surface  56  and the second heat transfer surface  106  generate heat which is transferred to the second fluid. Thus, the second fluid flows to the second heat exchanger  64  and the third heat exchanger  66  where heat is transferred from the second fluid to the air flowing in the air conduit  60 . Therefore, heated air is delivered to the passenger compartment of the vehicle from the first heat exchanger  62 , the second heat exchanger  64 , and the third heat exchanger  66 . It is understood that this mode can be used with only the first heat exchanger  62  transferring heat into the air stream, and the second heat exchanger  64  and the third heat exchanger  66  idle. 
         [0082]    In a second heating mode where the engine  40  is operating and the electric motor is operating, the first heat exchanger  62 , the second heat exchanger  64 , and the third heat exchanger  66  transfer heat into the air stream. The pump  52  of the second circuit  14  is operating to circulate the first fluid through the second conduit  38 . Heat is transferred into the first fluid by the engine  40 . 
         [0083]    The diverter valve  48  is positioned to militate against flow through the heat exchanger  42  and permit flow through the first bypass conduit  44 . Thus, heat is not removed from the first fluid in the heat exchanger  42  and the first fluid flows through the first bypass conduit  44 . The diverter valve  50  is in a position to militate against flow of the first fluid through the second bypass conduit  46 . Therefore, the first fluid flows through the second conduit  38  to the first heat exchanger  62  where heat is transferred from the first fluid to the air flowing in the air conduit  60 . 
         [0084]    The pump  18  of the first circuit  12  is operating to circulate the first fluid through the first conduit  16  to supply the first fluid to the first TED  54  and the second TED  102 . The pump  36  is not operating and the valves  32 ,  34  of the crossover conduits  28 ,  30  are closed to militate against flow therethrough. The first fluid flows through the battery compartment  22  where heat is transferred into the first fluid, flows through the first conduit  16 , and into thermal communication with the first heat transfer surface  55  of the first TED  54  and the first heat transfer surface  104  of the second TED  102 . The diverter valve  26  is positioned to militate against flow through the heat exchanger  20  and permit flow to the battery compartment  22 . Thus, heat is not removed from the first fluid in the heat exchanger  20 . The controller causes the current to the first TED  54  and the second TED  102  to flow to cause the first heat transfer surface  55  and the first heat transfer surface  104  to absorb heat to and remove heat from the first fluid. The first fluid then returns to the pump  18  for recirculation. 
         [0085]    The pump  124  is operating to circulate the second fluid through the third conduit  122 . The second fluid is in thermal communication with the second heat transfer surface  56  of the first TED  54  and the second heat transfer surface  106  of the second TED  102 . The second heat transfer surface  56  and the second heat transfer surface  106  generate heat which is transferred to the second fluid. Thus, the second fluid flows to the second heat exchanger  64  and the third heat exchanger  66  where heat is transferred from the second fluid to the air flowing in the air conduit  60 . 
         [0086]    Therefore, heated air is delivered to the passenger compartment of the vehicle from the first heat exchanger  62 , the second heat exchanger  64 , and the third heat exchanger  66 . It is understood that this mode can be used with only the first heat exchanger  62  transferring heat into the air stream, and the second heat exchanger  64  and the third heat exchanger  66  idle. It is understood that a third heating mode as described above for  FIG. 1  can be used with the first TED  54 , the second TED  102 , the second heat exchanger  64 , and the third heat exchanger  66  with the first heat exchanger  62  being idle. 
         [0087]    In a demisting mode, the engine  40  is not operating and the electric motor is operating. The first heat exchanger  62  is idle, the second heat exchanger  64  removes heat from the air stream, and the third heat exchanger  66  transfers heat into the air stream. It is understood that the engine  40  may have also been previously running and has residual heat stored therein, and that the second circuit  14  is operated as described for  FIG. 1  to remove heat from the engine  40 . Additionally, it is understood that the engine  40  could be operating, and that the second circuit  14  is operated as described for  FIG. 1  to remove heat from the engine  40 . 
         [0088]    The pump  18  of the first circuit  12  is operating to circulate the first fluid through the first conduit  16  to supply the first fluid to the first TED  54  and the second TED  102 . The pump  36  is not operating and the valves  32 ,  34  of the crossover conduits  28 ,  30  are closed to militate against flow therethrough. The diverter valve  26  is positioned to permit flow through the heat exchanger  20  and militate against flow to the battery compartment  22 . Thus, heat is removed from the first fluid in the heat exchanger  20 . The controller causes the current in the second TED  102  to flow to cause the first heat transfer surface  104  to generate heat which is absorbed by the first fluid. The controller causes the current to the first TED  54  to flow to cause the first heat transfer surface  55  to absorb heat which removes heat from the first fluid. The first fluid then returns to the pump  18  for recirculation. 
         [0089]    The pump  124  is operating to circulate the second fluid through the third conduit  122 . The second fluid is in thermal communication with the second heat transfer surface  56  of the first TED  54 . The second heat transfer surface  56  generates heat which is transferred to the second fluid. The second fluid flows to the third heat exchanger  66  where heat is transferred to the air flowing in the air conduit  60  to the second fluid. The second fluid flows to the second heat transfer surface  106  and is in thermal communication with the second heat transfer surface  106 . The second heat transfer surface  106  absorbs heat and removes heat from the second fluid. The second fluid flows to the second heat exchanger  64  where heat is removed from the air flowing in the air conduit  60  to the second fluid. 
         [0090]    Therefore, air is cooled in the second heat exchanger  64 , heated by the third heat exchanger  66 , and delivered to the passenger compartment of the vehicle for demisting. By initially cooling the air, moisture is caused to be removed from the air by condensation. 
         [0091]    In a cooling mode, where the engine  40  is not operating and the electric motor is operating, the second heat exchanger  64  and the third heat exchanger  66  remove heat from the air stream, and the first heat exchanger  62  is idle. It is understood that the engine  40  may have also been previously running and has residual heat stored therein, and that the second circuit  14  is operated as described for  FIG. 1  to remove heat from the engine  40 . Additionally, it is understood that the engine  40  could be operating, and that the second circuit  14  is operated as described for  FIG. 1  to remove heat from the engine  40 . 
         [0092]    The pump  18  of the first circuit  12  is operating to circulate the first fluid through the first conduit  16  to supply the first fluid to the first TED  54  and the second TED  102 . The pump  36  is not operating and the valves  32 ,  34  of the crossover conduits  28 ,  30  are closed to militate against flow therethrough. The diverter valve  26  is positioned to permit flow through the heat exchanger  20  and militate against flow to the battery compartment  22 . Thus, heat is removed from the first fluid in the heat exchanger  20 . The controller causes the current to the first TED  54  and the second TED  102  to flow to cause the first heat transfer surface  55  and the first heat transfer surface  104  to generate heat which is absorbed by the first fluid. The first fluid then returns to the pump  18  for recirculation. 
         [0093]    The pump  124  is operating to circulate the second fluid through the third conduit  122 . The second fluid is in thermal communication with the second heat transfer surface  56  of the first TED  54  and the second heat transfer surface  106  of the second TED  102 . The second heat transfer surface  56  and the second heat transfer surface  106  remove heat from the first fluid. Thus, the second fluid flows to the second heat exchanger  64  and the third heat exchanger  66  where heat is transferred from the air flowing in the air conduit  60  to the second fluid. Therefore, air is cooled in the second heat exchanger  64  and the third heat exchanger  66 , and delivered to the passenger compartment of the vehicle. 
         [0094]      FIG. 4  shows a heating ventilating, and air conditioning (HVAC) system  140  for supplying conditioned air to a passenger compartment of a vehicle according to another embodiment of the invention. Structure included from  FIGS. 1 and 2  has the same reference numeral for clarity and a description thereof is not repeated. 
         [0095]    In the embodiment shown, the first TED  54  and the second TED  102  include a third conduit  142  in thermal communication with both the second heat transfer surface  56  of the first TED  54  and the second heat transfer surface  106  of the second TED  102 . The third conduit  142  conveys a second fluid (not shown). The second fluid can be any conventional fluid such as air or a coolant such as a water-glycol coolant, for example. A pump  144  is disposed in the third conduit  142  to circulate the second fluid therethrough. 
         [0096]    The first heat exchanger  62  is in fluid communication with the second circuit  14 . The second heat exchanger  64  has an outlet  146  in fluid communication with the first TED  54  and an inlet  148  in fluid communication with the second TED  102 . The third heat exchanger  66  has an outlet  150  in fluid communication with the second TED  102  and an inlet  152  in fluid communication with the first TED  54 . The third conduit  142  circulates the second fluid between the first TED  54 , the third heat exchanger  66 , the second TED  102  and the second heat exchanger  64 . However, a diverter valve  154  is disposed in the third conduit  142  to selectively control flow of the second fluid from the first TED  54 . In a first position, the diverter valve  154  directs flow as described for  FIG. 3 . In a second position, the diverter valve  154  directs flow from the first TED  54 , to the second TED  102 , and back to the second heat exchanger  64 . Therefore, the third heat exchanger  66  is bypassed and the flow is similar to the flow of the second fluid described for  FIG. 1 . 
         [0097]    In operation, the system  140  conditions the air flowing from the source of air for supply of the conditioned air to the passenger compartment of the vehicle. A flow direction of the air from the source of air is indicated by the arrow in the air conduit  60 . Similar to the operation described for the systems  10 ,  100 ,  120  the system  140  can operate in a heating mode, a demisting mode, and a cooling mode. 
         [0098]    In a first heating mode where the engine  40  is operating and the electric motor is not operating, the first heat exchanger  62  and the second heat exchanger  64 , transfer heat into the air stream. The third heat exchanger  66  is idle. The pump  52  of the second circuit  14  is operating to circulate the first fluid through the second conduit  38 . Heat is transferred into the first fluid by the engine  40 . 
         [0099]    The diverter valve  48  is positioned to militate against flow through the heat exchanger  42  and permit flow through the first bypass conduit  44 . Thus, heat is not removed from the first fluid in the heat exchanger  42  and the first fluid flows through the first bypass conduit  44 . The diverter valve  50  is in a position to militate against flow of the first fluid through the second bypass conduit  46 . Therefore, the first fluid flows through the second conduit  38  to the first heat exchanger  62  where heat is transferred from the first fluid to the air flowing in the air conduit  60 . 
         [0100]    The pump  18  of the first circuit  12  is not operating to circulate the first fluid through the first conduit  16 . In order to supply the first fluid to the first TED  54  and the second TED  102 , the pump  36  is operating and the valves  32 ,  34  of the crossover conduits  28 ,  30  are open to permit flow therethrough. A portion of the flow of the first fluid in the second conduit  38  is directed through the crossover conduit  28  and into thermal communication with the first heat transfer surface  55  of the first TED  54  and the first heat transfer surface  104  of the second TED  102 . The controller causes the current to the first TED  54  and the second TED  102  to flow to cause the first heat transfer surface  55  and the first heat transfer surface  104  to absorb heat and remove heat from the first fluid. The first fluid then flows through the crossover conduit  30  to re-enter the second conduit  38  and flow to the first heat exchanger  62 . 
         [0101]    The pump  144  is operating to circulate the second fluid through the third conduit  142  and bypassing the third heat exchanger  66 . The diverter valve  154  is in a position to militate against flow of the second fluid to the third heat exchanger  66 . The second fluid is in thermal communication with the second heat transfer surface  56  of the first TED  54  and the second heat transfer surface  106  of the second TED  102 . The second heat transfer surface  56  and the second heat transfer surface  106  generate heat which is transferred to the second fluid. Thus, the second fluid flows to the second heat exchanger  64  where heat is transferred from the second fluid to the air flowing in the air conduit  60 . Therefore, heated air is delivered to the passenger compartment of the vehicle from the first heat exchanger  62  and the second heat exchanger  64 . It is understood that this mode can be used with only the first heat exchanger  62  transferring heat into the air stream, and the second heat exchanger  64  and the third heat exchanger  66  idle. It is further understood that this mode can be used as described above for  FIG. 3  to transfer heat into the air stream using the first heat exchanger  62 , the second heat exchanger  64  and the third heat exchanger  66 . 
         [0102]    In a second heating mode where the engine  40  is operating and the electric motor is operating, the first heat exchanger  62  and the second heat exchanger  64  transfer heat into the air stream. The pump  52  of the second circuit  14  is operating to circulate the first fluid through the second conduit  38 . Heat is transferred into the first fluid by the engine  40 . 
         [0103]    The diverter valve  48  is positioned to militate against flow through the heat exchanger  42  and permit flow through the first bypass conduit  44 . Thus, heat is not removed from the first fluid in the heat exchanger  42  and the first fluid flows through the first bypass conduit  44 . The diverter valve  50  is in a position to militate against flow of the first fluid through the second bypass conduit  46 . Therefore, the first fluid flows through the second conduit  38  to the first heat exchanger  62  where heat is transferred from the first fluid to the air flowing in the air conduit  60 . 
         [0104]    The pump  18  of the first circuit  12  is operating to circulate the first fluid through the first conduit  16  to supply the first fluid to the first TED  54  and the second TED  102 . The pump  36  is not operating and the valves  32 ,  34  of the crossover conduits  28 ,  30  are closed to militate against flow therethrough. The first fluid flows through the battery compartment  22  where heat is transferred into the first fluid, flows through the first conduit  16 , and into thermal communication with the first heat transfer surface  55  of the first TED  54  and the first heat transfer surface  104  of the second TED  102 . The diverter valve  26  is positioned to militate against flow through the heat exchanger  20  and permit flow to the battery compartment  22 . Thus, heat is not removed from the first fluid in the heat exchanger  20 . The controller causes the current to the first TED  54  and the second TED  102  to flow to cause the first heat transfer surface  55  and the first heat transfer surface  104  to absorb heat to and remove heat from the first fluid. The first fluid then returns to the pump  18  for recirculation. 
         [0105]    The pump  144  is operating to circulate the second fluid through the third conduit  142  and bypassing the third heat exchanger  66 . The diverter valve  154  is in a position to militate against flow of the second fluid to the third heat exchanger  66 . The second fluid is in thermal communication with the second heat transfer surface  56  of the first TED  54  and the second heat transfer surface  106  of the second TED  102 . The second heat transfer surface  56  and the second heat transfer surface  106  generate heat which is transferred to the second fluid. Thus, the second fluid flows to the second heat exchanger  64  where heat is transferred from the second fluid to the air flowing in the air conduit  60 . Therefore, heated air is delivered to the passenger compartment of the vehicle from the first heat exchanger  62  and the second heat exchanger  64 . It is understood that this mode can be used with only the first heat exchanger  62  transferring heat into the air stream, and the second heat exchanger  64  and the third heat exchanger  66  idle. It is further understood that this mode can be used as described above for  FIG. 3  to transfer heat into the air stream using the first heat exchanger  62 , the second heat exchanger  64  and the third heat exchanger  66 . 
         [0106]    In a demisting mode, the system  140  is used as described above for  FIG. 3   
         [0107]    In a cooling mode, where the engine  40  is not operating and the electric motor is operating, the second heat exchanger  64  removes heat from the air stream, and the first heat exchanger  62  and the third heat exchanger  66  are idle. It is understood that the engine  40  may have also been previously running and has residual heat stored therein, and that the second circuit  14  is operated as described for  FIG. 1  to remove heat from the engine  40 . Additionally, it is understood that the engine  40  could be operating, and that the second circuit  14  is operated as described for  FIG. 1  to remove heat from the engine  40 . 
         [0108]    The pump  18  of the first circuit  12  is operating to circulate the first fluid through the first conduit  16  to supply the first fluid to the first TED  54  and the second TED  102 . The pump  36  is not operating and the valves  32 ,  34  of the crossover conduits  28 ,  30  are closed to militate against flow therethrough. The diverter valve  26  is positioned to permit flow through the heat exchanger  20  and militate against flow to the battery compartment  22 . Thus, heat is removed from the first fluid in the heat exchanger  20 . The controller causes the current to the first TED  54  and the second TED  102  to flow to cause the first heat transfer surface  55  and the first heat transfer surface  104  to generate heat which is absorbed by the first fluid. The first fluid then returns to the pump  18  for recirculation. 
         [0109]    The pump  144  is operating to circulate the second fluid through the third conduit  142  and bypassing the third heat exchanger  66 . The diverter valve  154  is in a position to militate against flow of the second fluid to the third heat exchanger  66 . The second fluid is in thermal communication with the second heat transfer surface  56  of the first TED  54  and the second heat transfer surface  106  of the second TED  102 . The second heat transfer surface  56  and the second heat transfer surface  106  remove heat from the first fluid. Thus, the second fluid flows to the second heat exchanger  64  where heat is transferred from the air flowing in the air conduit  60  to the second fluid. Thus, the second fluid flows to the second heat exchanger  64  where heat is transferred from the second fluid to the air flowing in the air conduit  60 . Therefore, air is cooled in the second heat exchanger  64  and delivered to the passenger compartment of the vehicle. It is understood that this mode can be used as described above for  FIG. 3  to transfer heat from the air stream using the second heat exchanger  64  and the third heat exchanger  66 . 
         [0110]      FIG. 5  shows a heating ventilating, and air conditioning (HVAC) system  160  for supplying conditioned air to a passenger compartment of a vehicle according to another embodiment of the invention. The system  160  includes a first fluid circuit  162  and a second fluid circuit  164 . In the embodiment shown, the first circuit  162  communicates with components of an electric side of a hybrid vehicle (not shown) and the second circuit  164  communicates with components of a fuel fed side of the hybrid vehicle. A first fluid (not shown) is circulated in the first circuit  162  and the second circuit  164  and can be any conventional fluid such as air or a coolant such as a water-glycol coolant, for example. 
         [0111]    The first circuit  162  includes a first conduit  166  for conveying the first fluid through the first circuit  162 . A pump  168  is disposed in the first conduit  166  to circulate the first fluid therethrough. The first conduit  166  includes a heat exchanger  170  disposed therein. The heat exchanger  170  can be any conventional heat exchanger such as a low temperature core, for example. The first fluid is also circulated through a battery compartment or other source of heat  172  from the electric side of the hybrid vehicle to remove heat therefrom. In the embodiment shown, the battery compartment  172  is disposed in parallel with the heat exchanger  170 . However, it is understood that other configurations can be used as desired such as in series or a separate conduit, for example. A flow valve  174  and a diverter valve  176  are also disposed in the first conduit  166 . It is understood that more or fewer valves may be used as desired to control flow of the first fluid through the first conduit  166 . 
         [0112]    Crossover conduits  178 ,  180  are provided between the first circuit  162  and the second circuit  164 . Flow valves  182 ,  184  are provided in respective crossover conduits  178 ,  180  to selectively permit flow of the first fluid therethrough. 
         [0113]    A second conduit  186  is included in the second circuit  164 . The second conduit  186  is in fluid communication with an engine  188  of the hybrid vehicle to circulate the first fluid therethrough and remove heat therefrom. A heat exchanger  190  is disposed in the second conduit  186  downstream of the engine  188 . The heat exchanger  190  can be any conventional heat exchanger such as a radiator for the vehicle, for example. A first bypass conduit  192  is provided to permit bypassing of the heat exchanger  190  and a second bypass conduit  194  is provided to create a recirculation circuit. Flow through the second bypass conduit  194  is controlled by a flow valve  196 . It is understood that more or fewer valves may be used as desired to control flow of the first fluid through the second conduit  186 . A pump  198  is disposed in the second conduit  186  to circulate the first fluid therethrough. An expansion tank  200  is provided to account for expansion of the first fluid during operation of the system  160 . An exhaust gas heat recovery device  202  is provided to permit heat recovery from exhaust gases. 
         [0114]    A first thermoelectric device (TED)  204  is disposed adjacent the first conduit  166 . The first TED  204  includes a first heat transfer surface  206  and a second heat transfer surface  208 . The first heat transfer surface  206  is in thermal communication with the first conduit  166  of the first circuit  162 . The first TED  204  is in electrical communication with a control system (not shown). The control system controls an electric current sent to the first TED  204 . When the current is delivered in one direction, one of the first heat transfer surface  206  and the second heat transfer surface  208  generates thermal energy or heat, and the other of the first heat transfer surface  206  and the second heat transfer surface  208  absorbs thermal energy or heat. When the current is reversed, the one of the first heat transfer surface  206  and the second heat transfer surface  208  which was generating heat now absorbs heat and the other of the first heat transfer surface  206  and the second heat transfer surface  208  now generates heat. Additionally, when the current is increased, a heating and cooling capacity of the TED is increased. Likewise, when the current is decreased, the heating and cooling capacity of the TED is decreased. Although a single thermoelectric device is shown, it is understood that additional thermoelectric devices can be used, as desired. 
         [0115]    An air conduit  210  in fluid communication with a source of air (not shown) is provided to supply the conditioned air to the passenger compartment of the vehicle. The air conduit  210  includes a first heat exchanger  212  disposed therein. The heat exchanger  212  can be any conventional type of heat exchanger. The air conduit  210  is in thermal communication with the second heat transfer surface  208  of the first TED  204 . 
         [0116]    In operation, the system  160  conditions the air flowing from the source of air for supply of the conditioned air to the passenger compartment of the vehicle. A flow direction of the air from the source of air is indicated by the arrow in the air conduit  210 . The system  160  can operate in a heating mode and a cooling mode. Additionally, if a second TED is added as discussed for  FIGS. 2-4 , or if the first TED  204  is disposed upstream of the first heat exchanger  190 , the system  160  can operate in a demisting mode. 
         [0117]    In a first heating mode where the engine  188  is operating and the electric motor is not operating, the first heat exchanger  212  and the first TED  204  transfer heat into the air stream. The pump  168  of the first circuit  162  is not operating to circulate the first fluid through the first conduit  166 . The pump  198  of the second circuit  164  is operating to circulate the first fluid through the second conduit  186 . A portion of the flow of the first fluid may be permitted to flow through the heat exchanger  190 , or if additional valves are use, flow through the heat exchanger  190  can be militated against. Heat is transferred into the first fluid by the engine  188 . 
         [0118]    The valve  182  is positioned to permit flow of the first fluid from the engine  188  into thermal communication with the first heat transfer surface  206  of the first TED  204 . The controller causes the current to the first TED  204  to flow to cause the first heat transfer surface  206  to absorb heat and remove some heat from the first fluid. The first fluid then flows to the first heat exchanger  212 . The air flowing in the air conduit  210  is in thermal communication with the second heat transfer surface  208  of the first TED  204 . The second heat transfer surface  208  generates heat which is transferred to the air flowing in the air conduit  210 . 
         [0119]    The valve  184  is positioned to permit flow through the first heat exchanger  212 . In the first fluid flowing through the first heat exchanger  212 , heat is removed therefrom and transferred to the air flowing in the air conduit  210 . Therefore, heated air is delivered to the passenger compartment of the vehicle from the first heat exchanger  212  and the first TED  204 . 
         [0120]    In a second heating mode, where the engine  188  is not operating and the electric motor is operating, the first TED  204  transfers heat into the air stream. The pump  168  of the first circuit  162  is operating to circulate the first fluid through the first conduit  166 . The diverter valve  176  is positioned to militate against flow of the first fluid to the heat exchanger  170  and permit flow to the battery compartment  172 . Heat is transferred into the first fluid by the battery compartment  172 . The pump  198  of the second circuit  164  is not operating to circulate the first fluid through the second conduit  186 . It is understood that if the engine  188  is operating, or if there is residual heat in the engine  188  requiring removal, the pump  198  can be operated to cause the first fluid to flow through the heat exchanger  190  and recirculate back to the pump  198 . If this is necessary, the valve  196  is positioned to permit flow therethrough to recirculate the flow of the first fluid back to the pump  198 . 
         [0121]    The valve  182  is positioned to militate against flow of the first fluid from the engine  188  into thermal communication with the first heat transfer surface  206  of the first TED  204 . The valve  184  is positioned to militate against flow through the first heat exchanger  212 . 
         [0122]    The valve  174  is positioned to permit flow of the first fluid from the battery compartment  172  to the first heat transfer surface  206  of the first TED  204 . The controller causes the current to the first TED  204  to flow to cause the first heat transfer surface  206  to absorb heat and remove heat from the first fluid. The first fluid then flows back to the pump  168  for recirculation. The air flowing in the air conduit  210  is in thermal communication with the second heat transfer surface  208  of the first TED  204 . The second heat transfer surface  208  generates heat which is transferred to the air flowing in the air conduit  210 . Therefore, heated air is delivered to the passenger compartment of the vehicle from the first TED  204 . 
         [0123]    In a cooling mode, where the engine  188  is not operating and the electric motor is operating, the first TED  204  removes heat from the air stream. The pump  168  of the first circuit  162  is operating to circulate the first fluid through the first conduit  166 . The diverter valve  176  is positioned to militate against flow of the first fluid to the battery compartment  172  and permit flow to the heat exchanger  170 . Heat is removed from the first fluid by the heat exchanger  170 . The pump  198  of the second circuit  164  is not operating to circulate the first fluid through the second conduit  186 . It is understood that if the engine  188  is operating, or if there is residual heat in the engine  188  requiring removal, the pump  198  can be operated to cause the first fluid to flow through the heat exchanger  190  and recirculate back to the pump  198 . If this is necessary, the valve  196  is positioned to permit flow therethrough to recirculate the flow of the first fluid back to the pump  198 . 
         [0124]    The valve  182  is positioned to militate against flow of the first fluid from the engine  188  into thermal communication with the first heat transfer surface  206  of the first TED  204 . The valve  184  is positioned to militate against flow through the first heat exchanger  212 . 
         [0125]    The valve  174  is positioned to permit flow of the first fluid from the heat exchanger  170  to the first heat transfer surface  206  of the first TED  204 . The controller causes the current to the first TED  204  to flow to cause the first heat transfer surface  206  to generate heat which is absorbed by the first fluid. The first fluid then flows back to the pump  168  for recirculation. The air flowing in the air conduit  210  is in thermal communication with the second heat transfer surface  208  of the first TED  204 . The second heat transfer surface  208  absorbs heat from the air flowing in the air conduit  210 . Therefore, cooled air is delivered to the passenger compartment of the vehicle from the first TED  204 . 
         [0126]      FIG. 6  shows a heating ventilating, and air conditioning (HVAC) system  220  for supplying conditioned air to a passenger compartment of a vehicle according to another embodiment of the invention. Structure included from  FIG. 5  has the same reference numeral for clarity and a description thereof is not repeated. 
         [0127]    In the embodiment shown, a pump  222  is provided to selectively circulate the first fluid through the first conduit  166  and a crossover conduit  224 . A flow valve  226  is disposed in the crossover conduit  224  to selectively permit flow of the first fluid therethrough. It is understood that more or fewer valves may be used as desired. 
         [0128]    In operation, the system  220  conditions the air flowing from the source of air for supply of the conditioned air to the passenger compartment of the vehicle. A flow direction of the air from the source of air is indicated by the arrow in the air conduit  210 . The system  220  can operate in a heating mode and a cooling mode. Additionally, if a second TED is added as discussed for  FIGS. 2-4 , or if the first TED  204  is disposed upstream of the first heat exchanger  190 , the system  220  can operate in a demisting mode. 
         [0129]    In a first heating mode where the engine  188  is operating and the electric motor is not operating, the first heat exchanger  212  and the first TED  204  transfer heat into the air stream. The pump  222  is operating to circulate the first fluid through the crossover conduit  224 . The pump  198  of the second circuit  164  is operating to circulate the first fluid through the second conduit  186 . A portion of the flow of the first fluid may be permitted to flow through the heat exchanger  190 , or if additional valves are use, flow through the heat exchanger  190  can be militated against. Heat is transferred into the first fluid by the engine  188 . 
         [0130]    The valve  182  is positioned to permit flow of the first fluid from the engine  188  into thermal communication with the first heat transfer surface  206  of the first TED  204 . The controller causes the current to the first TED  204  to flow to cause the first heat transfer surface  206  to absorb heat and remove some heat from the first fluid. The first fluid then flows through to the pump  222 . The air flowing in the air conduit  210  is in thermal communication with the second heat transfer surface  208  of the first TED  204 . The second heat transfer surface  208  generates heat which is transferred to the air flowing in the air conduit  210 . 
         [0131]    The valve  226  is positioned to permit flow through the first heat exchanger  212 . In the first fluid flowing through the first heat exchanger  212 , heat is removed therefrom and transferred to the air flowing in the air conduit  210 . Therefore, heated air is delivered to the passenger compartment of the vehicle from the first heat exchanger  212  and the first TED  204 . 
         [0132]    In a second heating mode, where the engine  188  is not operating and the electric motor is operating, the first TED  204  transfers heat into the air stream. The pump  222  is operating to circulate the first fluid through the first conduit  166 . The diverter valve  176  is positioned to militate against flow of the first fluid to the heat exchanger  170  and permit flow to the battery compartment  172 . Heat is transferred into the first fluid by the battery compartment  172 . The pump  198  of the second circuit  164  is not operating to circulate the first fluid through the second conduit  186 . It is understood that if the engine  188  is operating, or if there is residual heat in the engine  188  requiring removal, the pump  198  can be operated to cause the first fluid to flow through the heat exchanger  190  and recirculate back to the pump  198 . If this is necessary, the valve  196  is positioned to permit flow therethrough to recirculate the flow of the first fluid back to the pump  198 . 
         [0133]    The valve  182  is positioned to militate against flow of the first fluid from the engine  188  into thermal communication with the first heat transfer surface  206  of the first TED  204 . The valve  226  is positioned to militate against flow through the first heat exchanger  212 . 
         [0134]    The valve  174  is positioned to permit flow of the first fluid from the battery compartment  172  to the first heat transfer surface  206  of the first TED  204 . The controller causes the current to the first TED  204  to flow to cause the first heat transfer surface  206  to absorb heat and remove heat from the first fluid. The first fluid then flows back to the pump  222  for recirculation. The air flowing in the air conduit  210  is in thermal communication with the second heat transfer surface  208  of the first TED  204 . The second heat transfer surface  208  generates heat which is transferred to the air flowing in the air conduit  210 . Therefore, heated air is delivered to the passenger compartment of the vehicle from the first TED  204 . 
         [0135]    In a cooling mode, where the engine  188  is not operating and the electric motor is operating, the first TED  204  removes heat from the air stream. The pump  222  is operating to circulate the first fluid through the first conduit  166 . The diverter valve  176  is positioned to militate against flow of the first fluid to the battery compartment  172  and permit flow to the heat exchanger  170 . Heat is removed from the first fluid by the heat exchanger  170 . The pump  198  of the second circuit  164  is not operating to circulate the first fluid through the second conduit  186 . It is understood that if the engine  188  is operating, or if there is residual heat in the engine  188  requiring removal, the pump  198  can be operated to cause the first fluid to flow through the heat exchanger  190  and recirculate back to the pump  198 . If this is necessary, the valve  196  is positioned to permit flow therethrough to recirculate the flow of the first fluid back to the pump  198 . 
         [0136]    The valve  182  is positioned to militate against flow of the first fluid from the engine  188  into thermal communication with the first heat transfer surface  206  of the first TED  204 . The valve  226  is positioned to militate against flow through the first heat exchanger  212 . 
         [0137]    The valve  174  is positioned to permit flow of the first fluid from the heat exchanger  170  to the first heat transfer surface  206  of the first TED  204 . The controller causes the current to the first TED  204  to flow to cause the first heat transfer surface  206  to generate heat which is absorbed by the first fluid. The first fluid then flows back to the pump  222  for recirculation. The air flowing in the air conduit  210  is in thermal communication with the second heat transfer surface  208  of the first TED  204 . The second heat transfer surface  208  absorbs heat from the air flowing in the air conduit  210 . Therefore, cooled air is delivered to the passenger compartment of the vehicle from the first TED  204 . 
         [0138]      FIG. 7  shows a heating ventilating, and air conditioning (HVAC) system  230  for supplying conditioned air to a passenger compartment of a vehicle according to another embodiment of the invention. Structure included from  FIGS. 5 and 6  has the same reference numeral for clarity and a description thereof is not repeated. 
         [0139]    In the embodiment shown, the valve  196  has been removed from the system. It is understood that more or fewer valves may be used as desired. 
         [0140]    In operation, the system  230  conditions the air flowing from the source of air for supply of the conditioned air to the passenger compartment of the vehicle. A flow direction of the air from the source of air is indicated by the arrow in the air conduit  210 . The system  230  can operate in a heating mode and a cooling mode. Additionally, if a second TED is added as discussed for  FIGS. 2-4 , or if the first TED  204  is disposed upstream of the first heat exchanger  190 , the system  230  can operate in a demisting mode. 
         [0141]    The operation of the system  230  is the same as described above for  FIG. 6 , except for the valve  196 . The valve  196  has been removed in the system  230 . Thus, it is not necessary to open a valve to permit recirculation of the flow of the first fluid through the second circuit  164 . 
         [0142]      FIG. 8  shows a heating ventilating, and air conditioning (HVAC) system  240  for supplying conditioned air to a passenger compartment of a vehicle according to another embodiment of the invention. Structure included from  FIGS. 5 ,  6 , and  7  has the same reference numeral for clarity and a description thereof is not repeated. 
         [0143]    In the embodiment shown, a point at which a return conduit  242  connects to the second conduit  186  has been changed. The return conduit  242  connects directly into the second conduit  186 , where the previous connection was made upstream of the exhaust gas heat recovery device  202 . The operation of the system  240  is the same as described above for  FIG. 7 . 
         [0144]    From the foregoing description, one ordinarily skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications to the invention to adapt it to various usages and conditions.