Patent Publication Number: US-9895953-B2

Title: Vehicle heat exchanger air flow control system

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to vehicles and, more particularly, to a vehicle radiator and condenser airflow system. 
     BACKGROUND OF THE INVENTION 
     In response to the demands of consumers who are driven both by ever-escalating fuel prices and the dire consequences of global warming, the automobile industry is slowly starting to embrace the need for ultra-low emission, high efficiency cars. While some within the industry are attempting to achieve these goals by engineering more efficient internal combustion engines, others are incorporating hybrid or all-electric drive trains into their vehicle line-ups. To meet consumer expectations, however, the automobile industry must not only achieve a greener drive train, but must do so while maintaining reasonable levels of performance, range, reliability, and cost. 
     In order to achieve the desired levels of performance and reliability in an electric vehicle, it is critical that the temperatures of the battery pack, power electronics, traction motor and related drive train components each remain within their respective operating temperature ranges regardless of ambient conditions or how hard the vehicle is being driven. Furthermore, in addition to controlling battery and drive train temperatures, the thermal management system must also be capable of heating and cooling the passenger cabin while not unduly affecting the vehicle&#39;s overall operating efficiency. In the past, thermal management systems have been configured in a variety of ways in order to meet these design goals. Regardless of the configuration, however, common to each of these approaches is the reliance on at least one, and typically more than one, heat exchanger. 
     Heat exchangers are designed to transfer heat between two similar or dissimilar fluids, where the fluids may be comprised of water or water with an additive, refrigerant, air, oil or other fluid. The performance associated with such a heat exchanger is based on a variety of factors including (i) the flow rate associated with each of the fluids through the heat exchanger, (ii) the surface area allotted for heat transfer between the two fluids, (iii) the thermal characteristics of the two fluids, and (iv) the temperature difference between the two fluids. 
     While not required, in a typical vehicle&#39;s thermal management system multiple heat exchangers are stacked together, i.e., positioned one in front of the other. A fan, either located in front or behind the stack, may be used to augment air flow through the stack, assuming that air is one of the fluids used by the heat exchanger(s). However while heat exchanger stacking is quite common, given the increased hydraulic losses in such an arrangement (e.g., fan power, aerodynamic drag, etc.) as well as the decrease in thermal efficiency and performance, it is not a preferred configuration when efficiency is a key design goal, such as in an electric vehicle. 
     U.S. Patent Publication 2012/0168125 discloses a thermal management system in which multiple heat exchangers are used in a non-stacking arrangement. Using multiple sets of louvers, the disclosed system allows air to be channeled in several different configurations, including (i) bypassing all heat exchangers, (ii) passing only through the side-mounted heat exchangers, (iii) serially passing through the central heat exchanger and then the side-mounted heat exchangers, or (iv) passing a portion of the intake air only through the side-mounted heat exchangers and a second portion of the intake air serially through the central heat exchanger and then the side-mounted heat exchangers. U.S. Patent Publication 2012/0168125 also discloses locating fans behind the side-mounted heat exchangers in order to augment air flow. 
     Although the prior art discloses numerous techniques for mounting and configuring the heat exchangers in a vehicle&#39;s thermal management system, an improved configuration is needed that allows the efficiencies associated with a non-stacking heat exchanger arrangement to be achieved while still providing a system that allows individual air flow control for each of the heat exchangers. The present invention provides such a heat exchanger configuration and control system. 
     SUMMARY OF THE INVENTION 
     The present invention provides an air flow control system for use with three non-stacked heat exchangers, the system comprising: (i) a first air inlet that corresponds to the first heat exchanger, where air flowing into the first air inlet passes directly into the first heat exchanger without passing through either the second or third heat exchangers; (ii) a second air inlet that corresponds to the second heat exchanger, where air flowing into the second air inlet passes directly into the second heat exchanger without passing through either the first or third heat exchangers; (iii) a third air inlet that corresponds to the third heat exchanger, where air flowing into the third air inlet passes directly into the third heat exchanger without passing through either the first or second heat exchangers; (iv) a first air duct that couples the first air outlet corresponding to the first heat exchanger to the second air inlet corresponding to the second heat exchanger; (v) a second air duct that couples the first air outlet corresponding to the first heat exchanger to the third air inlet corresponding to the third heat exchanger; (vi) a third air duct that couples the first air outlet corresponding to the first heat exchanger to the second air outlet corresponding to the second heat exchanger; and (vii) a fourth air duct that couples the first air outlet corresponding to the first heat exchanger to the third air outlet corresponding to the third heat exchanger. 
     In one aspect, the system may further include a first fan positioned adjacent to the second air outlet and configured to: (i) draw air through the second heat exchanger via a first pathway, where air following the first pathway passes through the second air inlet, the second heat exchanger, and through the second air outlet; (ii) draw air through the second heat exchanger via a second pathway, where air following the second pathway passes through the first air inlet, the first heat exchanger, the first air duct, the second heat exchanger, and through the second air outlet; and (iii) draw air around the second heat exchanger and bypass the second heat exchanger via a third pathway, where air following the third pathway passes through the first air inlet, the first heat exchanger, the third air duct, and through the second air outlet. The system may further include a second fan positioned adjacent to the third air outlet and configured to: (i) draw air through the third heat exchanger via a fourth pathway, where air following the fourth pathway passes through the third air inlet, the third heat exchanger, and through the third air outlet; (ii) draw air through the third heat exchanger via a fifth pathway, where air following the fifth pathway passes through the first air inlet, the first heat exchanger, the second air duct, the third heat exchanger, and through the third air outlet; and (iii) draw air around the third heat exchanger and bypass the third heat exchanger via a sixth pathway, where air following the sixth pathway passes through the first air inlet, the first heat exchanger, the fourth air duct, and through the third air outlet. 
     In another aspect, the system may further include a first air control surface incorporated into the first air duct and a second air control surface incorporated into the second air duct. The first air control surface is adjustable between a first air control surface closed position and a first air control surface open position, where air flowing through the first heat exchanger flows through the first air duct and into the second heat exchanger via the second air inlet when the first air control surface is in the first air control surface open position, and where air flow between the first air outlet and the second air inlet is terminated when the first air control surface is in the first air control surface closed position. Preferably the first air control surface is adjustable over a first range of positions between and including the first air control surface open and closed positions. The second air control surface is adjustable between a second air control surface closed position and a second air control surface open position, where air flowing through the first heat exchanger flows through the second air duct and into the third heat exchanger via the third air inlet when the second air control surface is in the second air control surface open position, and where air flow between the first air outlet and the third air inlet is terminated when the second air control surface is in the second air control surface closed position. Preferably the second air control surface is adjustable over a second range of positions between and including the second air control surface open and closed positions. 
     In another aspect, the system may further include a third air control surface incorporated into the third air duct and a fourth air control surface incorporated into the fourth air duct. The third air control surface is adjustable between a third air control surface closed position and a third air control surface open position, where air flowing through the first heat exchanger flows through the third air duct and through the second air outlet and bypasses the second heat exchanger when the third air control surface is in the third air control surface open position, and where air flow between the first air outlet and the second air outlet is terminated when the third air control surface is in the third air control surface closed position. Preferably the third air control surface is adjustable over a third range of positions between and including the third air control surface open and closed positions. The fourth air control surface is adjustable between a fourth air control surface closed position and a fourth air control surface open position, where air flowing through the first heat exchanger flows through the fourth air duct and through the third air outlet and bypasses the third heat exchanger when the fourth air control surface is in the fourth air control surface open position, and wherein air flow between the first air outlet and the third air outlet is terminated when the fourth air control surface is in the fourth air control surface closed position. Preferably the fourth air control surface is adjustable over a fourth range of positions between and including the fourth air control surface open and closed positions. The third air duct may be coupled to the first air duct at a first juncture and the third air control surface may be integrated into the first juncture. The fourth air duct may be coupled to the second air duct at a second juncture and the fourth air control surface may be integrated into the second juncture. 
     In another aspect, the system may further include a fifth air control surface integrated into the second air inlet and a sixth air control surface integrated into the third air inlet. The fifth air control surface is adjustable between a fifth air control surface closed position and a fifth air control surface open position, such that air is permitted to flow into the second heat exchanger via the second air inlet when the fifth air control surface is in the fifth air control surface open position, and air is not permitted to flow into the second heat exchanger via the second air inlet when the fifth air control surface is in the fifth air control surface closed position. Preferably the fifth air control surface is adjustable over a fifth range of positions between and including the fifth air control surface open and closed positions. The sixth air control surface is adjustable between a sixth air control surface closed position and a sixth air control surface open position, such that air is permitted to flow into the third heat exchanger via the third air inlet when the sixth air control surface is in the sixth air control surface open position, and air is not permitted to flow into the third heat exchanger via the third air inlet when the sixth air control surface is in the sixth air control surface closed position. Preferably the sixth air control surface is adjustable over a sixth range of positions between and including the sixth air control surface open and closed positions. 
     In another aspect, the first heat exchanger may be comprised of a pair of side-by-side heat exchangers. The first air inlet corresponding to the first heat exchanger may be comprised of a pair of side-by-side air inlets that correspond to the pair of side-by-side heat exchangers. 
     A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       It should be understood that the accompanying figures are only meant to illustrate, not limit, the scope of the invention and should not be considered to be to scale. Additionally, the same reference label on different figures should be understood to refer to the same component or a component of similar functionality. 
         FIG. 1  provides a schematic illustration of a preferred embodiment of the heat exchanger air flow control system of the invention; 
         FIG. 2  provides an illustration of the embodiment shown in  FIG. 1  with the air duct flaps set such that air flows directly through the central heat exchanger and does not flow through either side-mounted heat exchanger; 
         FIG. 3  provides an illustration of the embodiment shown in  FIG. 1  with the air duct flaps set such that air flows directly through both side-mounted heat exchangers and indirectly through the central heat exchanger; 
         FIG. 4  provides an illustration of the embodiment shown in  FIG. 1  with the air duct flaps set such that air flows directly through both side-mounted heat exchangers and bypasses the central heat exchanger; 
         FIG. 5  provides an illustration of the embodiment shown in  FIG. 1  with the air duct flaps set such that air flows directly through both side-mounted heat exchangers and both directly and indirectly through the central heat exchanger; 
         FIG. 6  provides an illustration of the embodiment shown in  FIG. 1  with the air duct flaps set such that air flows directly through both side-mounted heat exchangers as well as the central heat exchanger; 
         FIG. 7  provides an illustration of the embodiment shown in  FIG. 1  with the air duct flaps set such that air flows directly through both side-mounted heat exchangers and both directly and indirectly through the central heat exchanger; 
         FIG. 8  provides an illustration of the embodiment shown in  FIG. 1  with the air duct flaps set such that air flows directly through the central heat exchanger and one of the side-mounted heat exchangers; 
         FIG. 9  provides a schematic illustration of an alternate heat exchanger air flow control system in accordance with the invention; 
         FIG. 10  provides an illustration of the embodiment shown in  FIG. 9  with the air duct flaps set such that air flows directly through both side-mounted heat exchangers and does not flow through the central heat exchanger; 
         FIG. 11  provides an illustration of the embodiment shown in  FIG. 9  with the air duct flaps set such that air flows directly through the central heat exchanger and then through both side-mounted heat exchangers; 
         FIG. 12  provides an illustration of the embodiment shown in  FIG. 9  with the air duct flaps set such that air flows directly through the central heat exchanger and then through air outlets, bypassing both side-mounted heat exchangers; 
         FIG. 13  provides an illustration of the embodiment shown in  FIG. 9  with the air duct flaps set such that air flows directly through all three heat exchangers as well as indirectly through both side-mounted heat exchangers after passing through the central heat exchanger; 
         FIG. 14  provides an illustration of the embodiment shown in  FIG. 9  with the air duct flaps set such that air only flows directly through the three heat exchangers; 
         FIG. 15  provides an illustration of the embodiment shown in  FIG. 9  with all of the air duct flaps open, thus allowing air to flow through all three air inlets and follow all six possible air flow pathways; 
         FIG. 16  provides an illustration of the embodiment shown in  FIG. 9  with the air duct flaps set such that air flows through the central heat exchanger and one of the side-mounted heat exchangers; 
         FIG. 17  provides a schematic illustration of a modification of the heat exchanger air flow control system shown in  FIG. 9 , the modified system replacing the central heat exchanger with a pair of side-by-side mounted heat exchangers; 
         FIG. 18  provides a schematic illustration of a modification of the heat exchanger air flow control system shown in  FIG. 9 , the modified system replacing the central heat exchanger with a pair of side-by-side mounted heat exchangers and the central air duct with a pair of side-by-side air ducts; and 
         FIG. 19  provides a block diagram of an exemplary control system for use with a heat exchanger air flow control system such as those shown in  FIGS. 1-18 . 
     
    
    
     DESCRIPTION OF THE SPECIFIC EMBODIMENTS 
     As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises”, “comprising”, “includes”, and/or “including”, as used herein, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” and the symbol “/” are meant to include any and all combinations of one or more of the associated listed items. Additionally, while the terms first, second, etc. may be used herein to describe various steps or calculations, these steps or calculations should not be limited by these terms, rather these terms are only used to distinguish one step or calculation from another. For example, a first calculation could be termed a second calculation, and, similarly, a first step could be termed a second step, without departing from the scope of this disclosure. The terms “electric vehicle” and “EV” may be used interchangeably and may refer to an all-electric vehicle, a plug-in hybrid vehicle, also referred to as a PHEV, or a hybrid vehicle, also referred to as a HEV, where a hybrid vehicle utilizes multiple sources of propulsion including an electric drive system. The terms “thermal control circuit” and “thermal control loop” may be used interchangeably. 
       FIG. 1  provides a schematic illustration of a preferred embodiment of a heat exchanger air control system  100  in accordance with the invention. System  100  includes a central heat exchanger  101  and a pair of side-mounted heat exchangers  102  and  103 , where the side-mounted heat exchangers  102 / 103  are positioned forward of the central heat exchanger  101 . While the approach used in system  100  may be used with a single side-mounted heat exchanger, in a vehicle there are numerous advantages to using a symmetrical approach. It will be understood that heat exchangers  101 - 103 , as well as the heat exchangers described relative to the other configurations of the invention, may be coupled to any of a variety of vehicle components associated with the vehicle&#39;s thermal management system (e.g., refrigeration system, passenger HVAC system, drive train components, battery pack, power electronics, etc.). Similarly, the heat exchangers of the invention are not limited to use with a specific thermal management system configuration. 
     In system  100  there are three air inlets  105 - 107  associated with heat exchangers  101 - 103 , respectively. When the car moves forward in a direction  109 , air is directed into each of these air inlets. The outlet from each of the side-mounted heat exchangers, i.e., outlet  111  corresponding to heat exchanger  102  and outlet  112  corresponding to heat exchanger  103 , is split into two outlet ducts. One of the two outlet ducts associated with each side-mounted heat exchanger, i.e., duct  113  associated with outlet  111  and duct  114  associated with outlet  112 , are coupled to central intake  105 . As such, air passing through one or both of the side-mounted heat exchangers and flowing through one or both of the air ducts  111 / 112  will be directed into the intake of heat exchanger  101 . The second of the two outlet ducts associated with each side-mounted heat exchanger, i.e., duct  115  associated with outlet  111  and duct  116  associated with outlet  112 , are coupled to the central outlet duct  117 . Preferably a single fan  119  is located at the outlet of central duct  117 . It will be appreciated that fan  119  may augment air flow through any or all of the heat exchangers, depending upon the settings associated with the various duct flaps described below. 
     In order to provide air flow control throughout heat exchanger system  100 , multiple flaps are incorporated throughout the air duct system. Each of these flaps may be fabricated as a single flap, or door, that can be varied between a fully open position that provides minimal air flow restriction through the corresponding air duct, and a fully closed position that substantially eliminates air flow through the corresponding air duct. Alternately, these flaps may be fabricated to incorporate a plurality of smaller flaps, or vanes, which can be varied between the fully open and fully closed positions. It should be understood that the terms “flap”, “vane”, “air vane”, “air control surface”, “louver” and “door” may be used interchangeably and as used herein refer to one or more air control surfaces incorporated into an air duct and which may be rotated, or whose position may be otherwise altered, in order to vary the flow of air through the corresponding air duct between an open position in which air flow is minimally affected to a closed position in which air flow is substantially terminated. Preferably the air duct flaps are adjustable within a range of positions between and including the open and closed positions. 
     In system  100 , five flaps are incorporated into the air ducts, thereby allowing complete control over the five air flow pathways associated with this configuration. A central flap  123  is incorporated into central air inlet  105 , flap  123  controlling air flow passing directly into central heat exchanger  101 . Flaps  125  and  126  are incorporated into air ducts  113  and  114 , respectively, and control the air that flows first through a side-mounted heat exchanger (e.g., exchangers  102  and  103 ) and then through the central heat exchanger  101 . Flaps  127  and  128 , incorporated into air ducts  115  and  116 , respectively, permit air to flow only through a side-mounted heat exchanger before being exhausted via central outlet duct  117 . 
       FIGS. 2-8  illustrate seven different air duct control flap set-ups for system  100 , these views showing a variety of exemplary air flow configurations. As flaps  123 ,  125 / 126 , and  127 / 128  are preferably independently operable, it will be appreciated that  FIGS. 2-8  only illustrate some of the possible air flow patterns. For example, due to independent flap control, one of the side-mounted heat exchangers could be active while the other side-mounted heat exchanger is not. Briefly,  FIGS. 2-8  illustrate the following air flow patterns:
         In  FIG. 2 , flap  123  is open and flaps  125 ,  126 ,  127  and  128  are closed. As such, air follows pathway  201  and passes only through inlet  105  and the central heat exchanger  101  before being expelled through outlet air duct  117 .   In  FIG. 3 , flaps  125  and  126  are open and flaps  123 ,  127  and  128  are closed. As such, air following pathway  301  passes through inlet  106 , side-mounted heat exchanger  102 , and then through central heat exchanger  101  before being expelled through outlet air duct  117 . Similarly, air following pathway  303  passes through inlet  107 , side-mounted heat exchanger  103 , and then through central heat exchanger  101  before being expelled through outlet air duct  117 .   In  FIG. 4 , flaps  127  and  128  are open and flaps  123 ,  125  and  126  are closed. As such, air follows pathway  401  through inlet  106  and then through side-mounted heat exchanger  102  before being expelled through outlet air duct  117 . Similarly, air follows pathway  403  through inlet  107  and then through side-mounted heat exchanger  103  before being expelled through outlet air duct  117 . In this flap configuration there is no air flow through central heat exchanger  101 .   In  FIG. 5 , flaps  123 ,  125  and  126  are open and flaps  127  and  128  are closed. As such, air flows into and through the heat exchangers following three pathways, i.e., pathways  201 ,  301  and  303 . Therefore in this configuration air flows through central heat exchanger  101  both directly via inlet  105 , and indirectly via inlets  106 / 107  and side-mounted heat exchangers  102 / 103 .   In  FIG. 6 , flaps  123 ,  127  and  128  are open and flaps  125  and  126  are closed. As such, air flows into and through the heat exchangers following three pathways, i.e., pathways  201 ,  401  and  403 . Therefore in this configuration air flows through central heat exchanger  101  only directly through inlet  105  since the air passing through the side-mounted heat exchangers bypasses the central heat exchanger, instead flowing out through outlet air duct  117  via air ducts  115  and  116 .   In  FIG. 7 , all flaps are open and as such, air flows into and through the heat exchangers following five pathways, i.e., pathways  201 ,  301 ,  303 ,  401  and  403 .     FIG. 8  illustrates a configuration in which only one of the side-mounted heat exchangers is in use. As shown, flaps  123  and  128  are open and flaps  125 ,  126  and  127  are closed. As a result of this configuration, air flows directly through central heat exchanger  101  via air inlet  105  (i.e., pathway  201 ) and directly through side-mounted heat exchanger  103  via air inlet  107  (i.e., pathway  403 ). Since flaps  125  and  126  are closed, air does not flow indirectly through the central heat exchanger  101 . Additionally since flaps  125  and  127  are closed, air does not flow through side-mounted heat exchanger  102 .       

       FIG. 9  provides a schematic illustration of a second preferred embodiment of the invention. In system  900 , the central heat exchanger  901  is mounted forward of the side-mounted heat exchangers  902  and  903 . As in the prior embodiment, associated with each heat exchanger is an air inlet, i.e., inlets  905 - 907  correspond to heat exchangers  901 - 903 , respectively. The outlet from the central heat exchanger  901  is split into four ducts  909 - 912 , with two of the air ducts (i.e., ducts  909  and  910 ) associated with side-mounted heat exchanger  902  and two of the air ducts (i.e., ducts  911  and  912 ) associated with side-mounted heat exchanger  903 . One of each pair of ducts couples the output of the central heat exchanger to the inlet of one of the side-mounted heat exchangers. Accordingly, air duct  909  couples the output of central heat exchanger  901  to inlet  906  of heat exchanger  902  and air duct  911  couples the output of central heat exchanger  901  to inlet  907  of heat exchanger  903 . The second duct of each pair of ducts couples the output of the central heat exchanger to the outlet of one of the side-mounted heat exchangers, thereby bypassing the associated side-mounted heat exchanger. Accordingly, air duct  910  couples the output of central heat exchanger  901  to outlet  913  of heat exchanger  902  and air duct  912  couples the output of central heat exchanger  901  to outlet  914  of heat exchanger  903 . Preferably a pair of fans  915 / 916  is used to augment air flow through the heat exchangers. As shown in  FIG. 9 , depending upon the duct flap settings, fan  915  may be used to augment air flow through either, or both, heat exchangers  901  and  902  while fan  916  may be used to augment air flow through either, or both, heat exchangers  901  and  903 . 
     In order to provide air flow control in heat exchanger system  900 , three sets of flaps are incorporated throughout the air duct system. Preferably the flaps incorporated into system  900 , as are those incorporated into system  100 , are independently operable, thus maximizing thermal management system flexibility. Each of these flaps may be fabricated as a single flap, or door, or a plurality of smaller flaps, or vanes, that can be varied between a fully open position that provides minimal air flow restriction through the corresponding air duct, and a fully closed position that substantially eliminates air flow through the corresponding air duct. 
     In system  900 , six flaps are incorporated into the air ducts, thereby allowing complete control over the six air flow pathways associated with this configuration. Flaps  917  and  918  are incorporated into the air inlets associated with side-mounted heat exchangers  902  and  903 , respectively, and control the flow of air entering directly into the side-mounted heat exchangers. A second set of flaps  919  and  920  are incorporated into ducts  909  and  911 , respectively, and control the flow of air entering the air inlets of the side-mounted heat exchangers from the outlet of the central heat exchanger. A third set of flaps  921  and  922  are incorporated into ducts  910  and  912 , respectively, and control the flow of air entering the air outlets of the side-mounted heat exchangers from the outlet of the central heat exchanger, thus bypassing the side-mounted heat exchangers. 
       FIGS. 10-16  illustrate seven different air duct control flap set-ups for system  900 , these views showing a variety of exemplary air flow configurations. It should be understood that  FIGS. 10-16  only illustrate some of the possible air flow patterns through the heat exchangers of system  900 , and other configurations are clearly possible using flaps  917 - 922 . Briefly,  FIGS. 10-16  illustrate the following air flow patterns:
         In  FIG. 10 , flaps  917  and  918  are open and flaps  919 - 922  are closed. As such, air follows pathway  1001  and passes through inlet  906  and side-mounted heat exchanger  902  before being expelled through outlet air duct  913 . Similarly, air follows pathway  1003  and passes through inlet  907  and side-mounted heat exchanger  903  before being expelled through outlet air duct  914 .   In  FIG. 11 , flaps  919  and  920  are open and flaps  917 ,  918 ,  921  and  922  are closed. As such, air follows pathway  1101  through inlet  905 , through central heat exchanger  901 , and then through side-mounted heat exchanger  902  before being expelled through outlet air duct  913 . Similarly, air follows pathway  1103  through inlet  905 , through central heat exchanger  901 , and then through side-mounted heat exchanger  903  before being expelled through outlet air duct  914 .   In  FIG. 12 , flaps  921  and  922  are open and flaps  917 - 920  are closed. As such, air follows pathway  1201  through inlet  905 , central heat exchanger  901  and then through outlet air duct  913 , bypassing side-mounted heat exchanger  902 . Similarly, air follows pathway  1203  through inlet  905 , central heat exchanger  901  and then through outlet air duct  914 , bypassing side-mounted heat exchanger  903 .   In  FIG. 13 , flaps  917 - 920  are open and flaps  921  and  922  are closed. As such, air follows pathways  1001 ,  1003 ,  1101  and  1103  and flows directly into all three heat exchangers and indirectly through the side-mounted heat exchangers after passing through central heat exchanger  901 .   In  FIG. 14 , flaps  917 ,  918 ,  921  and  922  are open and flaps  919  and  920  are closed. As such, air follows pathways  1001 ,  1003 ,  1201  and  1203  and flows directly into all three heat exchangers. In this configuration there is not indirect air flow through the side-mounted heat exchangers.   In  FIG. 15 , all flaps are open and as such, air flows into and through the heat exchangers following six pathways, i.e., pathways  1001 ,  1003 ,  1101 ,  1103 ,  1201  and  1203 .   In  FIG. 16 , flaps  917 ,  919  and  922  are open and flaps  918 ,  920  and  921  are closed. As such, air flows directly through side-mounted heat exchanger  902  following pathway  1001  and through central heat exchanger  901  following pathways  1101  and  1203 . The air flowing through the central heat exchanger passes through side-mounted heat exchanger  902  and through air outlet  914 , thereby bypassing side-mounted heat exchanger  903 .       

       FIG. 17  provides a schematic illustration of a modification of the embodiment shown in  FIGS. 9-16 . In system  1700 , central heat exchanger  901  is replaced by a pair of side-by-side heat exchangers  1701  and  1702 . In a further modification of system  900  shown in  FIG. 18 , in addition to replacing central heat exchanger  901  by a pair of side-by-side heat exchangers  1701 / 1702 , central air duct  905  is replaced by a pair of side-by-side, centrally located, air ducts  1801  and  1802  that correspond to heat exchangers  1701  and  1702 , thereby allowing separation of the air flow pathways on the left and right side of the vehicle. 
       FIG. 19  is a block diagram of an exemplary control system  1900  for use with a thermal management system utilizing the heat exchanger system shown in anyone of  FIGS. 1-18 . Control system  1900  includes a system controller  1901 . System controller  1901  may be the same controller used to perform other vehicle functions, e.g., system controller  1901  may be a vehicle system controller that may be used to control any of a variety of vehicle subsystems, e.g., navigation system, entertainment system, suspension (e.g., air suspension), battery charging, vehicle performance monitors, etc. Alternately, system controller  1901  may be separate from the vehicle&#39;s system controller. System controller  1901  includes a central processing unit (CPU)  1903  and a memory  1905 . Memory  1905  may be comprised of EPROM, EEPROM, flash memory, RAM, a solid state disk drive, a hard disk drive, or any other memory type or combination of memory types. Memory  1905  may be used to store preset operating temperature ranges for the vehicle&#39;s battery pack, drive train, power system, etc. If the vehicle uses a touch-screen or similar display means  1907  as a user interface, controller  1901  may also include a graphical processing unit (GPU)  1909 . CPU  1903  and GPU  1909  may be separate or contained on a single chip set. 
     Preferably coupled to controller  1901  are a variety of temperature sensors that monitor the temperatures of various components and subsystems under the control of the thermal control system, thereby allowing the system controller to determine optimal heat exchanger door flap settings. Exemplary temperature sensors may include one or more temperature sensors  1911  that monitor battery pack temperature; one or more temperature sensors  1913  that monitor the drive train; one or more temperature sensors  1915  that monitor the temperature of the heat transfer fluid within the thermal control loops including those thermal control loops utilizing the heat exchangers of the invention; one or more temperature sensors  1917  that monitor the state of the refrigerant in a thermal control loop utilizing a heat exchanger of the invention; one or more temperature sensors  1919  that monitor passenger cabin temperature; one or more temperature sensors  1921  that monitor ambient temperature; and one or more temperature sensors  1923  that monitor the sun load. Typically a HVAC system interface  1925  is also coupled to controller  1901  in order to allow the desired passenger cabin temperature to be set by the driver and/or passengers, where the desired temperature may be configured to either be set by zone or a single temperature for the entire cabin. HVAC system interface  1925  may be a HVAC dedicated interface, e.g., temperature control switches mounted within the passenger cabin, or may utilize a common user interface such as display interface  1907 . 
     Also coupled to the thermal management system, and in particular controller  1901 , are a variety of components that are used to maintain each of the vehicle&#39;s subsystems (e.g., battery pack, drive train components, passenger cabin, etc.) within their desired temperature range while optimizing overall system efficiency. Accordingly, coupled to and controlled by controller  1901  may be heat transfer flow control valves  1927 ; refrigerant expansion valves  1929 ; refrigeration system compressor  1931 ; heat transfer fluid circulating pumps  1933 ; blower fans  119 ,  915  and  916 ; and air duct control flaps  123 ,  125 ,  126 ,  127 ,  128  and  917 - 922 . 
     Systems and methods have been described in general terms as an aid to understanding details of the invention. In some instances, well-known structures, materials, and/or operations have not been specifically shown or described in detail to avoid obscuring aspects of the invention. In other instances, specific details have been given in order to provide a thorough understanding of the invention. One skilled in the relevant art will recognize that the invention may be embodied in other specific forms, for example to adapt to a particular system or apparatus or situation or material or component, without departing from the spirit or essential characteristics thereof. Therefore the disclosures and descriptions herein are intended to be illustrative, but not limiting, of the scope of the invention.