Abstract:
A thermal energy heat exchanger for an air conditioning system includes a row of first tubes, a row of second tubes, and a row of third tubes. Inside, heat is exchanged between air, refrigerant, and phase change material, also known as PCM, cool storage material, cold storage material, and latent heat storage material. The first row of tubes carries refrigerant. A portion of the second row of tubes and a portion of the third row of tubes carry refrigerant. The remainder of the second and third rows of tubes carry phase change material. The phase change material can be associated with a phase change material manifold. Advantageously, the melting point of phase change material in the second tubes can be different from the melting point of the phase change material in the third tubes.

Description:
FIELD OF THE INVENTION 
     The invention relates to a climate control system for a vehicle and more particularly to a heating, ventilating, and air conditioning system of a vehicle having a thermal energy exchanger disposed therein. 
     BACKGROUND OF THE INVENTION 
     A vehicle typically includes a climate control system which maintains a temperature within a passenger compartment of the vehicle at a comfortable level by providing heating, cooling, and ventilation. Comfort is maintained in the passenger compartment by an integrated mechanism referred to in the art as a heating, ventilating and air conditioning (HVAC) system. The HVAC system conditions air flowing therethrough and distributes the conditioned air throughout the passenger compartment. 
     Typically, a compressor of a refrigeration system provides a flow of a fluid having a desired temperature to an evaporator disposed in the HVAC system to condition the air. The compressor is generally driven by a fuel-powered engine of the vehicle. However, in recent years, vehicles having improved fuel economy over the fuel-powered engine and other vehicles are quickly becoming more popular as a cost of traditional fuel increases. The improved fuel economy is due to known technologies such as regenerative braking, electric motor assist, and engine-off operation. Although the technologies improve fuel economy, accessories powered by the fuel-powered engine no longer operate when the fuel-powered engine is not in operation. One major accessory that does not operate is the compressor of the refrigeration system. Therefore, without the use of the compressor, the evaporator disposed in the HVAC system does not condition the air flowing therethrough and the temperature of the passenger compartment increases to a point above a desired temperature. 
     Accordingly, vehicle manufacturers have used a thermal energy exchanger disposed in the HVAC system to condition the air flowing therethrough when the fuel-powered engine is not in operation. One such thermal energy exchanger, also referred to as a cold accumulator, is described in U.S. Pat. No. 6,854,513 entitled VEHICLE AIR CONDITIONING SYSTEM WITH COLD ACCUMULATOR, hereby incorporated herein by reference in its entirety. The cold accumulator includes a phase change material, also referred to as a cold accumulating material, disposed therein. The cold accumulating material absorbs heat from the air when the fuel-powered engine is not in operation. The cold accumulating material is then recharged by the conditioned air flowing from the cooling heat exchanger when the fuel-powered engine is in operation. 
     In U.S. Pat. No. 6,691,527 entitled AIR-CONDITIONER FOR A MOTOR VEHICLE, hereby incorporated herein by reference in its entirety, a thermal energy exchanger is disclosed having a phase change material disposed therein. The phase change material of the thermal energy exchanger conditions a flow of air through the HVAC system when the fuel-powered engine of the vehicle is not in operation. The phase change material is charged by a flow of a fluid from the refrigeration system therethrough. 
     While the prior art HVAC systems perform adequately, it is desirable to produce a thermal energy exchanger having a phase change material disposed therein for an HVAC system, wherein an effectiveness and efficiency thereof are maximized. 
     SUMMARY OF THE INVENTION 
     In concordance and agreement with the present invention, a thermal energy exchanger having a phase change material disposed therein for an HVAC system, wherein an effectiveness and efficiency thereof are maximized, has surprisingly been discovered. 
     In one embodiment, the thermal energy exchanger for a heating, ventilating, and air conditioning system comprises: a plurality of first tubes, wherein at least one of the first tubes receives a fluid therein; and a plurality of second tubes disposed downstream of the first tubes, wherein at least one of the second tubes receives the fluid therein and at least one of the tubes includes a phase change material disposed therein, and wherein the at least one of the second tubes receiving the fluid therein and the at least one of the second tubes including the phase change material disposed therein are alternatingly arranged. 
     In another embodiment, the thermal energy exchanger for a heating, ventilating, and air conditioning system comprises: a plurality of first tubes, wherein the first tubes receive a fluid therein; a plurality of second tubes disposed downstream of the first tubes, wherein at least one of the second tubes receives the fluid therein and at least one of the second tubes includes a phase change material disposed therein; and a plurality of third tubes disposed downstream of the second tubes, wherein at least one of the third tubes receives the fluid therein and at least one of the third tubes includes a phase change material disposed therein, the at least one of the third tubes having the phase change material disposed therein is laterally offset in respect of the at least one of the second tubes having the phase change material disposed therein. 
     In yet another embodiment, the thermal energy exchanger for a heating, ventilating, and air conditioning system comprises: a plurality of first tubes, wherein at least a portion of the first tubes receives a fluid therein; and a plurality of second tubes disposed downstream of the first tubes, wherein a first portion of at least one of the second tubes receives the fluid therein and a second portion of the at least one of the second tubes includes a phase change material disposed therein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above, as well as other objects and advantages of the invention, will become readily apparent to those skilled in the art from reading the following detailed description of various embodiments of the invention when considered in the light of the accompanying drawings in which: 
         FIG. 1  is a schematic flow diagram of an HVAC system including a fragmentary sectional view of an HVAC module having a thermal energy exchanger disposed therein according to an embodiment of the invention; 
         FIG. 2  is a schematic perspective view of the thermal energy exchanger according to an embodiment of the present invention showing a portion of two layers of the thermal energy exchanger cutaway; 
         FIG. 3  is a cross-sectional view of the thermal energy exchanger illustrated in  FIG. 2  taken along section line  3 - 3 , wherein a plurality of tubes includes an internal web formed therein; 
         FIG. 4  is a schematic perspective view of the thermal energy exchanger according to another embodiment of the present invention showing a portion of two layers of the thermal energy exchanger cutaway; 
         FIG. 5  is an cross-sectional elevational view of a thermal energy exchanger according to another embodiment of the invention, the section taken along a plane substantially parallel to a direction of air flow through the thermal energy exchanger, wherein the thermal energy exchanger includes a plurality of divided tubes having a phase change material disposed in a portion thereof; 
         FIG. 6  is an cross-sectional elevational view of a thermal energy exchanger according to another embodiment of the invention, the section taken along a plane substantially parallel to a direction of air flow through the thermal energy exchanger, wherein the thermal energy exchanger includes a plurality of divided tubes having a phase change material disposed in a portion thereof; 
         FIG. 7  is an cross-sectional elevational view of a thermal energy exchanger according to another embodiment of the invention, the section taken along a plane substantially parallel to a direction of air flow through the thermal energy exchanger, wherein the thermal energy exchanger includes a plurality of divided tubes having a phase change material disposed in a portion thereof; 
         FIG. 8  is an cross-sectional elevational view of a thermal energy exchanger according to another embodiment of the invention, the section taken along a plane substantially parallel to a direction of air flow through the thermal energy exchanger, wherein the thermal energy exchanger includes a plurality of divided tubes having a phase change material disposed in a portion thereof, and wherein at least one of the tubes has a substantially U-shaped flow path; 
         FIG. 9  is an cross-sectional elevational view of a thermal energy exchanger according to another embodiment of the invention, the section taken along a plane substantially parallel to a direction of air flow through the thermal energy exchanger, wherein the thermal energy exchanger includes a plurality of divided tubes having a phase change material disposed in a portion thereof, and wherein at least one of the tubes has a pair of substantially parallel flow paths; 
         FIG. 10  is an cross-sectional elevational view of a thermal energy exchanger according to another embodiment of the invention, the section taken along a plane substantially parallel to a direction of air flow through the thermal energy exchanger, wherein the thermal energy exchanger includes a plurality of divided tubes having a phase change material disposed in a portion thereof, and wherein at least one of the tubes having the phase change material disposed therein is closed by a cover; 
         FIG. 11  is an cross-sectional elevational view of a thermal energy exchanger according to another embodiment of the invention, the section taken along a plane substantially parallel to a direction of air flow through the thermal energy exchanger, wherein the thermal energy exchanger includes a plurality of divided tubes having a phase change material disposed in a portion thereof, and wherein at least one of the tubes has a substantially serpentine shaped flow path; 
         FIG. 12  is a fragmentary cross-sectional elevational view of a thermal energy exchanger according to another embodiment of the invention, the section taken along a plane substantially perpendicular to a direction of air flow through the thermal energy exchanger, wherein the thermal energy exchanger includes a plurality of tubes in fluid communication with an upper fluid manifold, a phase change material manifold formed around at least a portion of the tubes, and a secondary phase change material manifold disposed in the upper fluid manifold; 
         FIG. 13  is a fragmentary cross-sectional elevational view of a thermal energy exchanger according to another embodiment of the invention, the section taken along a plane substantially perpendicular to a direction of air flow through the thermal energy exchanger, wherein the thermal energy exchanger includes a plurality of tubes in fluid communication with an upper fluid manifold, a phase change material manifold formed around at least a portion of the tubes, and a secondary phase change material manifold disposed adjacent an outer surface of the upper fluid manifold; 
         FIG. 14  is a fragmentary cross-sectional elevational view of a thermal energy exchanger according to another embodiment of the invention, the section taken along a plane substantially perpendicular to a direction of air flow through the thermal energy exchanger, wherein the thermal energy exchanger includes a plurality of tubes in fluid communication with an upper fluid manifold, a phase change material manifold formed around at least a portion of the tubes, and a secondary phase change material manifold disposed around at least a portion of an outer periphery of the thermal energy exchanger; and 
         FIG. 15  is a fragmentary cross-sectional elevational view of a thermal energy exchanger according to another embodiment of the invention, the section taken along a plane substantially perpendicular to a direction of air flow through the thermal energy exchanger, wherein the thermal energy exchanger includes a plurality of first tubes in fluid communication with an upper fluid manifold, a plurality of second tubes in fluid communication with a plurality of phase change material manifolds, and a secondary phase change material manifold disposed around at least a portion of an outer periphery of the thermal energy exchanger. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     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. 
       FIG. 1  shows a heating, ventilating, and air conditioning (HVAC) system  10  according to an embodiment of the invention. The HVAC system  10  typically provides heating, ventilation, and air conditioning for a passenger compartment of a vehicle (not shown). The HVAC system  10  includes a control module  12  to control at least a temperature of the passenger compartment. 
     The module  12  illustrated includes a hollow main housing  14  with an air flow conduit  15  formed therein. The housing  14  includes an inlet section  16 , a mixing and conditioning section  18 , and an outlet and distribution section (not shown). In the embodiment shown, an air inlet  22  is formed in the inlet section  16 . The air inlet  22  is in fluid communication with a supply of air (not shown). The supply of air can be provided from outside of the vehicle, recirculated from the passenger compartment of the vehicle, or a mixture of the two, for example. The inlet section  16  is adapted to receive a blower wheel (not shown) therein to cause air to flow through the air inlet  22 . A filter (not shown) can be provided upstream or downstream of the inlet section  16  if desired. 
     The mixing and conditioning section  18  of the housing  14  is adapted to receive an evaporator core  24 , a thermal energy exchanger  26 , and a heater core  28  therein. A filter (not shown) can also be provided upstream of the evaporator core  24 , if desired. The evaporator core  24  is in fluid communication with a source of cooled fluid  30  such as a refrigeration system, for example, through a conduit  36 . The source of cooled fluid  30  includes a fluid circulating therein. The fluid absorbs thermal energy and conditions the air flowing through the HVAC module  12 . 
     The thermal energy exchanger  26  can also be in fluid communication with the source of cooled fluid  30  through a conduit  38 . A valve  39  can be disposed in the conduit  38  to selectively militate against a flow of the fluid therethrough. The thermal energy exchanger  26  is adapted to absorb thermal energy and cool the air flowing therethrough when a fuel-powered engine of the vehicle is not in operation. The thermal energy exchanger  26  is adapted to receive the fluid from the source of cooled fluid  30  therethrough. 
     As shown, the heater core  28  is fluidly connected to a source of heated fluid  40  by a conduit  42 . The source of heated fluid  40  can be any conventional source of heated fluid such as the fuel-powered engine of the vehicle, for example, and the heated fluid can be any conventional fluid such as an engine coolant, for example. A valve  44  can be disposed in the conduit  42  to selectively militate against a flow of heated fluid therethrough. The heater core  28  is adapted to release thermal energy and heat the air flowing therethrough when the fuel-powered engine of the vehicle is in operation. 
     In particular embodiments, the thermal energy exchanger  26  and the heater core  28  are disposed in a first passage  29  downstream of a selectively positionable blend door  50 . In an engine-off cooling mode of the HVAC system  10 , the blend door  50  is positioned in a first position permitting air from the evaporator  24  to only flow into the first passage  29  and through the thermal energy exchanger  26  and the heater core  28 . In a pull-down mode of the HVAC system  10 , the blend door  50  is positioned in a second position permitting air from the evaporator  24  to only flow into a second passage  52  to bypass the thermal energy exchanger  26  and the heater core  28 . In a thermal energy exchanger charge mode of the HVAC system  10 , the blend door  50  is positioned in an intermediate position between the first and second positions permitting air from the evaporator  24  to flow into both the first and second passages  29 ,  52  and through the thermal energy exchanger  26  and the heater core  28 . 
     As illustrated in  FIG. 2 , the thermal energy exchanger  26  of the embodiment shown is a multi-layer louvered-fin heat exchanger. It is understood that the thermal energy exchanger  26  can be any conventional thermal energy exchanger as desired. In a non-limiting example, the thermal energy exchanger  26  has a first layer  60 , a second layer  62 , and a third layer  64  arranged substantially perpendicular to an air-flowing direction. Additional or fewer layers than shown can be employed as desired. The layers  60 ,  62 ,  64  are arranged so the second layer  62  is disposed downstream of the first layer  60  and upstream of the third layer  64 . It is understood, however, that the layers  60 ,  62 ,  64  can be arranged as desired. The layers  60 ,  62 ,  64  can be bonded together by any suitable method as desired such as brazing and welding, for example. 
     Each of the layers  60 ,  62 ,  64  of the thermal energy exchanger  26  includes an upper first fluid manifold  66 ,  68 ,  70  and a lower second fluid manifold  72 ,  74 ,  76 , respectively. A plurality of first tubes  78  extends between the fluid manifolds  66 ,  72  of the first layer  60 . A plurality of second tubes  80  extends between the fluid manifolds  68 ,  74  of the second layer  62 . A plurality of third tubes  82  extends between the fluid manifolds  70 ,  76  of the third layer  64 . In particular embodiments, each of the first upper fluid manifolds  66 ,  68 ,  70  is an inlet manifold which distributes the fluid into at least a portion of the tubes  78 ,  80 ,  82  and each of the second lower fluid manifolds  72 ,  74 ,  76  is an outlet manifold which collects the fluid from at least a portion of the tubes  78 ,  80 ,  82 . 
     Each of the tubes  78 ,  80 ,  82  is provided with louvered fins  84  formed thereon. The fins  84  abut an outer surface of the tubes  78 ,  80 ,  82  for enhancing thermal energy transfer of the thermal energy exchanger  26 . The fins  84  include a plurality of crests  86  formed thereon. The crests  86  are formed substantially parallel to each other and at a substantially 90 degree angle to the tubes  78 ,  80 ,  82 . It is understood that the crests  86  can be formed at any angle to the tubes  78 ,  80 ,  82  if desired. Each of the crests  86  defines an air space  88  extending between the tubes  78 ,  80 ,  82  and the fins  84 . The tubes  78 ,  80 ,  82  of the thermal energy exchanger  26  can further include a plurality of internal fins  89  formed on an inner surface thereof. The internal fins further enhance the transfer of thermal energy of the thermal energy exchanger  26 . It is understood, however, that the thermal energy exchanger  26  can be constructed as a finless heat exchanger if desired. 
       FIGS. 1-3  show a configuration of the thermal energy exchanger  26  according to one embodiment of the invention. Each of the tubes  78  of the first layer  60  includes a passage  90  formed therein. The passage  90  fluidly connects the fluid manifolds  66 ,  72  and receives the fluid therein. As illustrated in  FIG. 3 , the second layer  62  includes two sets A, B of the tubes  80 , each set A, B having a passage  92  formed therein. The tubes  80  of set A and the tubes  80  of set B are arranged in an alternating pattern. The passage  92  formed in the tubes  80  of set A fluidly connects the fluid manifolds  68 ,  74  and receives the fluid therein. The passage  92  formed in the tubes  80  of set B includes a phase change material (PCM)  94  disposed therein and is in fluid communication with a PCM manifold  96  shown in  FIG. 2 . Each of the PCM manifolds  96  extends between a pair of tubes  80  of set A and includes the PCM  94  disposed therein. The PCM manifolds  96  are sealed to militate against leakage of the PCM  94  into the fluid. In certain embodiments, the tubes  80  of set B and the PCM manifolds  96  are filled by heating the PCM  94  above a melting point thereof until the PCM  94  is a liquid which can be easily poured into an opening (not shown) of the PCM manifolds  96 . The PCM  94  absorbs thermal energy from the air flowing through the thermal energy exchanger  26  when the fuel-powered engine is not in operation. Accordingly, when the fuel-powered engine of the vehicle is in operation, the PCM  94  releases thermal energy into conditioned air from the evaporator  24  flowing therethrough. 
     Similarly, the third layer  64  includes two sets C, D of the tubes  82 , each set C, D having a passage  98  formed therein. The tubes  82  of set C and the tubes  82  of set D are arranged in an alternating pattern. The passage  98  formed in the tubes  82  of set C fluidly connects the fluid manifolds  70 ,  76  and receives the fluid therein. The passage  98  formed in the tubes  82  of set D includes a PCM  100  disposed therein and is in fluid communication with a PCM manifold  102 . Each of the PCM manifolds  102  extends between a pair of tubes  82  of set C and includes the PCM  100  disposed therein. The PCM manifolds  102  are sealed to militate against leakage of the PCM  100  into the fluid. In certain embodiments, the tubes  82  of set D and the PCM manifolds  102  are filled by heating the PCM  100  above a melting point thereof until the PCM  100  is a liquid which can be easily poured into an opening (not shown) of the PCM manifolds  102 . 
     The PCM  100  absorbs thermal energy from the air flowing through the thermal energy exchanger  26  when the fuel-powered engine is not in operation. Accordingly, when the fuel-powered engine of the vehicle is in operation, the PCM  100  releases thermal energy into conditioned air from the evaporator  24  flowing therethrough. As shown in  FIGS. 2 and 3 , the tubes  80  of set B are laterally offset with respect of the tubes  82  of set D so the PCM  100  cools to a lower temperature during the thermal energy exchanger charge mode of the HVAC system  10 . 
     Each of the PCMs  94 ,  100  is any material that melts and solidifies at predetermined temperatures and is capable of storing and releasing thermal energy such as a paraffin wax, an alcohol, water, and any combination thereof, for example. In particular embodiments, the PCMs  94 ,  100  are different materials of which the melting point of the PCM  94  is higher than the melting point of the PCM  100 . For example, the PCM  94  can have a melting point in a range of about 12° C. to about 14° C. and the PCM  100  can have a melting point in a range of about 6° C. to about 9° C. so the third layer  64  can further cool the air which has passed through the second layer  62 . It is understood, however, that the PCMs  94 ,  100  can be the same material if desired. The PCMs  94 ,  100  can also be impregnated with a thermally conductive material such as graphite powder, for example, to further enhance the transfer of thermal energy. 
     As shown in  FIG. 3 , an internal web  104  may be formed in at least one of the tubes  80  of set B and the tubes  82  of set D. The web  104  is formed between opposing walls  106 ,  108  of the tubes  80 ,  82  of the respective sets B, D, substantially parallel to a longitudinal axis thereof. The web  104  shown has a substantially hourglass-shaped cross-section arranged substantially perpendicular to the air-flowing direction through the thermal energy exchanger  26 . The web  104  enhances thermal energy conduction from the air flowing through the thermal energy exchanger  26  to the PCM  94  disposed in the tubes  80  of set B and the PCM  100  disposed in the tubes  82  of set D. 
       FIG. 4  illustrates an alternative configuration of the thermal energy exchanger  26 . In  FIG. 4 , the thermal energy exchanger  126  has a first layer  130 , a second layer  132 , and a third layer  134  arranged substantially perpendicular to an air-flowing direction. Additional or fewer layers than shown can be employed as desired. The layers  130 ,  132 ,  134  are arranged so the second layer  132  is disposed downstream of the first layer  130  and upstream of the third layer  134 . It is understood, however, that the layers  130 ,  132 ,  134  can be arranged as desired. The layers  130 ,  132 ,  134  can be bonded together by any suitable method as desired such as brazing and welding, for example. 
     Each of the layers  130 ,  132 ,  134  of the thermal energy exchanger  126  includes an upper first fluid manifold  136 ,  138 ,  140  and a lower second fluid manifold  142 ,  144 ,  146 , respectively. A plurality of first tubes  148  extends between the fluid manifolds  136 ,  142  of the first layer  130 . A plurality of second tubes  150  extends between the fluid manifolds  138 ,  144  of the second layer  132 . A plurality of third tubes  152  extends between the fluid manifolds  140 ,  146  of the third layer  134 . In particular embodiments, each of the upper first fluid manifolds  136 ,  138 ,  140  is an inlet manifold which distributes the fluid into at least a portion of the tubes  148 ,  150 ,  152  and each of the lower second fluid manifolds  142 ,  144 ,  146  is an outlet manifold which collects the fluid from at least a portion of the tubes  148 ,  150 ,  152 . 
     Each of the tubes  148 ,  150 ,  152  is provided with louvered fins  154  formed thereon. The fins  154  abut an outer surface of the tubes  148 ,  150 ,  152  for enhancing thermal energy transfer of the thermal energy exchanger  126 . The fins  154  include a plurality of crests  156  formed thereon. The crests  156  are formed substantially parallel to each other and at a substantially 90 degree angle to the tubes  148 ,  150 ,  152 . It is understood that the crests  156  can be formed at any angle to the tubes  148 ,  150 ,  152  if desired. Each of the crests  156  defines an air space  158  extending between the tubes  148 ,  150 ,  152  and the fins  154 . 
     Each of the tubes  148  of the first layer  130  includes a passage (not shown) formed therein. The passage fluidly connects the fluid manifolds  136 ,  142  and receives the fluid therein. Similar to  FIG. 3 , the second layer  132  includes two sets A, B of the tubes  150 , each set A, B of the tubes  150  having a passage  159  formed therein. The tubes  150  of set A and the tubes  150  of set B are arranged in an alternating pattern. Each of the tubes  150  of set B of the second layer  132  are in fluid communication with an outer PCM manifold  160  through a conduit  162 . The conduits  162  shown have a circular cross-sectional shape and a diameter smaller than a diameter of the tubes  150  of set B. As illustrated, the tubes  150  of set B and the PCM manifold  160  includes a PCM  164  disposed therein. The PCM manifold  160  is sealed to militate against leakage of the PCM  164  into the fluid. The tubes  150  of set B are filled by heating the PCM  164  above a melting point thereof until the PCM  164  is a liquid which can be easily poured into an opening (not shown) of the PCM manifold  160 . The liquid PCM  164  flows from the PCM manifold  160  through the conduits  162  into the tubes  150  of set B. The PCM  164  absorbs thermal energy from the air flowing through the thermal energy exchanger  126  when the fuel-powered engine is not in operation. Accordingly, when the fuel-powered engine of the vehicle is in operation, the PCM  164  releases thermal energy into conditioned air from the evaporator  24  flowing therethrough. 
     The third layer  134  includes two sets C, D of the tubes  152 , each set C, D of the tubes  152  having a passage  166  formed therein. The tubes  152  of set C and the tubes  152  of set D are arranged in an alternating pattern. Each of the tubes  152  of set D of the third layer  134  are in fluid communication with an outer PCM manifold  170  through a conduit  172 . The conduits  172  shown have a substantially oval cross-sectional shape and a diameter smaller than a diameter of the tubes  152  of set D. It is understood, however, that the conduits  172  can have any shape and size as desired. As illustrated, the tubes  152  of set D and the PCM manifold  170  includes a PCM  174  disposed therein. The PCM manifold  170  is sealed to militate against leakage of the PCM  174  into the fluid. The tubes  152  of set D are filled by heating the PCM  174  above a melting point thereof until the PCM  174  is a liquid which can be easily poured into an opening (not shown) of the PCM manifold  170 . The liquid PCM  174  flows from the PCM manifold  170  through the conduits  172  into the tubes  152  of set D. It is understood that the PCM manifold  170  and the PCM manifold  160  can be integrally formed if desired. 
     The PCM  174  absorbs thermal energy from the air flowing through the thermal energy exchanger  126  when the fuel-powered engine is not in operation. Accordingly, when the fuel-powered engine of the vehicle is in operation, the PCM  174  releases thermal energy into conditioned air from the evaporator flowing therethrough. As shown, the tubes  150  of set B are laterally offset with respect of the tubes  152  of set D so the PCM  174  cools to a lower temperature during the thermal energy exchanger charge mode of the HVAC system  10 . 
     Each of the PCMs  164 ,  174  is any material that melts and solidifies at predetermined temperatures and is capable of storing and releasing thermal energy such as a paraffin wax, an alcohol, water, and any combination thereof, for example. In particular embodiments, the PCMs  164 ,  174  are different materials of which the melting point of the PCM  164  is higher than the melting point of the PCM  174 . For example, the PCM  164  can have a melting point in a range of about 12° C. to about 14° C. and the PCM  174  can have a melting point in a range of about 6° C. to about 9° C. so the third layer  134  can further cool the air which has passed through the second layer  132 . It is understood, however, that the PCMs  164 ,  174  can be the same material if desired. The PCMs  164 ,  174  can also be impregnated with a thermally conductive material such as graphite powder, for example, to further enhance the transfer of thermal energy. 
     An internal web (not shown) similar to the web  104  in  FIG. 3  may be formed in at least one of the tubes  150  of set B and the tubes  152  of set D to enhance thermal energy conduction from the air flowing through the thermal energy exchanger  126  to the PCM  164  disposed in the tubes  150  of set B and the PCM  174  disposed in the tubes  152  of set D. 
     Alternatively, at least one of the tubes  148 ,  150 ,  152  of the thermal energy exchanger  126  can further include a plurality of internal fins (not shown) similar to the fins  89  in  FIG. 2  formed on an inner surface thereof. The internal fins further enhance the transfer of thermal energy of the thermal energy exchanger  126 . It is understood, however, that the thermal energy exchanger  126  can be constructed as a finless heat exchanger if desired. 
     The remaining structure of the HVAC system  10  is substantially the same as described above for the embodiment illustrated in  FIGS. 1-3 . 
       FIG. 5  illustrates an alternative configuration of the thermal energy exchanger  26 . In  FIG. 5 , the thermal energy exchanger  226  has a first layer  230 , a second layer  232 , and a third layer  234  arranged substantially perpendicular to an air-flowing direction. Additional or fewer layers than shown can be employed as desired. The layers  230 ,  232 ,  234  are arranged so the second layer  232  is disposed downstream of the first layer  230  and upstream of the third layer  234 . It is understood, however, that the layers  230 ,  232 ,  234  can be arranged as desired. The layers  230 ,  232 ,  234  can be bonded together by any suitable method as desired such as brazing and welding, for example. 
     Each of the layers  230 ,  232 ,  234  of the thermal energy exchanger  226  includes an upper divided manifold  236 ,  238 ,  240  and a lower fluid manifold  242 ,  244 ,  246 , respectively. A plurality of first tubes  248  extends between the manifolds  236 ,  242  of the first layer  230 . A plurality of second tubes  250  extends between the manifolds  238 ,  244  of the second layer  232 . A plurality of third tubes  252  extends between the manifolds  240 ,  246  of the third layer  234 . In certain embodiments, each of the tubes  248 ,  250 ,  252  is provided with louvered fins (not shown) formed thereon. The fins abut an outer surface of the tubes  248 ,  250 ,  252  for enhancing thermal energy transfer of the thermal energy exchanger  226 . 
     As shown, each of the tubes  248  of the first layer  230  is a divided tube having a first portion  260  and a second portion  262 . The portions  260 ,  262  are formed substantially parallel to a longitudinal axis of the tubes  248  and arranged so the first portion  260  is positioned upstream of the second portion  262  in respect of the air-flowing direction. Each of the portions  260 ,  262  includes a passage  264  formed therein. The passage  264  formed in the first portion  260  of the tubes  248  fluidly connects a first portion  266  of the divided manifold  236  and the fluid manifold  242 . The first portion  266  of the divided manifold  236 , the first portion  260  of the tubes  248 , and the fluid manifold  242  receive the fluid therein. In particular embodiments, the first portion  266  of the divided manifold  236  is an inlet manifold which distributes the fluid into the first portion  260  of the tubes  248  and the fluid manifold  242  is an outlet manifold which collects the fluid from the first portion  266  of the tubes  248 . The passage  264  formed in the second portion  262  of the tubes  248  is in fluid communication with a second portion  268  of the divided manifold  236 . The second portion  262  of the tubes  248  and the second portion  268  of the divided manifold  236  include a PCM  269  disposed therein. 
     Each of the tubes  250  of the second layer  232  is a divided tube having a first portion  270  and a second portion  272 . The portions  270 ,  272  are formed substantially parallel to a longitudinal axis of the tubes  250  and arranged so the first portion  270  is positioned upstream of the second portion  272  in respect of the air-flowing direction. Each of the portions  270 ,  272  includes a passage  274  formed therein. The passage  274  formed in the first portion  270  of the tubes  250  fluidly connects a first portion  276  of the divided manifold  238  and the fluid manifold  244 . The first portion  276  of the divided manifold  238 , the first portion  270  of the tubes  250 , and the fluid manifold  244  receive the fluid therein. In particular embodiments, the first portion  276  of the divided manifold  238  is an inlet manifold which distributes the fluid into the first portion  270  of the tubes  250  and the fluid manifold  244  is an outlet manifold which collects the fluid from the first portion  276  of the tubes  250 . The passage  274  formed in the second portion  272  of the tubes  250  is in fluid communication with a second portion  278  of the divided manifold  238 . The second portion  272  of the tubes  250  and the second portion  278  of the divided manifold  238  include a PCM  279  disposed therein. 
     Each of the tubes  252  of the third layer  234  is a divided tube having a first portion  280  and a second portion  282 . The portions  280 ,  282  are formed substantially parallel to a longitudinal axis of the tubes  252  and arranged so the first portion  280  is positioned upstream of the second portion  282  in respect of the air-flowing direction. Each of the portions  280 ,  282  includes a passage  284  formed therein. The passage  284  formed in the first portion  280  of the tubes  252  fluidly connects a first portion  286  of the divided manifold  240  and the fluid manifold  246 . The first portion  286  of the divided manifold  240 , the first portion  280  of the tubes  252 , and the fluid manifold  246  receive the fluid therein. In particular embodiments, the first portion  286  of the divided manifold  240  is an inlet manifold which distributes the fluid into the first portion  280  of the tubes  252  and the fluid manifold  246  is an outlet manifold which collects the fluid from the first portion  286  of the tubes  252 . The passage  284  formed in the second portion  282  of the tubes  252  is in fluid communication with a second portion  288  of the divided manifold  240 . The second portion  282  of the tubes  252  and the second portion  288  of the divided manifold  240  include a PCM  289  disposed therein. 
     Each of the PCMs  269 ,  279 ,  289  is any material that melts and solidifies at predetermined temperatures and is capable of storing and releasing thermal energy such as a paraffin wax, an alcohol, water, and any combination thereof, for example. In particular embodiments, the PCMs  269 ,  279 ,  289  are different materials of which the melting point of the PCM  279  is higher than the melting point of the PCM  269  and the melting point of the PCM  289  is higher than the melting points of the PCMs  269 ,  279  so the second layer  232  can further cool the air which has pass through the first layer  230  and the third layer  234  can further cool the air which has passed through the first and second layers  230 ,  232 . It is understood, however, that the PCMs  269 ,  279 ,  289  can be the same material if desired. The PCMs  269 ,  279 ,  289  can also be impregnated with a thermally conductive material such as graphite powder, for example, to further enhance the transfer of thermal energy. 
     An internal web (not shown) similar to the web  104  in  FIG. 3  may be formed in at least one of the second portions  262 ,  272 ,  282  of the tubes  248 ,  250 ,  252 , respectively, to enhance thermal energy conduction from the air flowing through the thermal energy exchanger  226 . Alternatively, at least one of the second portions  262 ,  272 ,  282  of the tubes  248 ,  250 ,  252  can further include a plurality of internal fins (not shown) similar to the fins  89  in  FIG. 2  formed on an inner surface thereof. The internal fins further enhance the transfer of thermal energy of the thermal energy exchanger  226 . 
     The remaining structure of the HVAC system  10  is substantially the same as described above for the embodiments illustrated in  FIGS. 1-4 . 
       FIG. 6  illustrates an alternative configuration of the thermal energy exchanger  26 . In  FIG. 6 , the thermal energy exchanger  326  has a first layer  330 , a second layer  332 , and a third layer  334  arranged substantially perpendicular to an air-flowing direction. Additional or fewer layers than shown can be employed as desired. The layers  330 ,  332 ,  334  are arranged so the second layer  332  is disposed downstream of the first layer  330  and upstream of the third layer  334 . It is understood, however, that the layers  330 ,  332 ,  334  can be arranged as desired. The layers  330 ,  332 ,  334  can be bonded together by any suitable method as desired such as brazing and welding, for example. 
     The first layer  330  of the thermal energy exchanger  326  includes an upper first divided manifold  336  and a lower fluid manifold  342 . Each of the second layer  332  and the third layer  334  of the thermal energy exchanger  326  includes an upper first divided manifold  338 ,  340  and a lower second divided manifold  344 ,  346 , respectively. A plurality of first tubes  348  extends between the manifolds  336 ,  342  of the first layer  330 . A plurality of second tubes  350  extends between the manifolds  338 ,  344  of the second layer  332 . A plurality of third tubes  352  extends between the manifolds  340 ,  346  of the third layer  334 . In certain embodiments, each of the tubes  348 ,  350 ,  352  is provided with louvered fins (not shown) formed thereon. The fins abut an outer surface of the tubes  348 ,  350 ,  352  for enhancing thermal energy transfer of the thermal energy exchanger  326 . 
     As shown, each of the tubes  348  of the first layer  330  is a divided tube having a first portion  360  and a second portion  362 . The portions  360 ,  362  are formed substantially parallel to a longitudinal axis of the tubes  348  and arranged so the first portion  360  is positioned upstream of the second portion  362  in respect of the air-flowing direction. Each of the portions  360 ,  362  includes a passage  364  formed therein. The passage  364  formed in the first portion  360  of the tubes  348  fluidly connects a first portion  366  of the divided manifold  336  and the fluid manifold  342 . The first portion  366  of the divided manifold  336 , the first portion  360  of the tubes  348 , and the fluid manifold  342  receive the fluid therein. In particular embodiments, the first portion  366  of the divided manifold  336  is an inlet manifold which distributes the fluid into the first portion  360  of the tubes  348  and the fluid manifold  342  is an outlet manifold which collects the fluid from the first portion  360  of the tubes  348 . The passage  364  formed in the second portion  362  of the tubes  348  is in fluid communication with a second portion  368  of the divided manifold  336 . The second portion  362  of the tubes  348  and the second portion  368  of the divided manifold  336  include a PCM  369  disposed therein. As shown, a volume of the second portion  368  of the divided manifold  336  is about one-fourth a volume of the first portion  366  of the divided manifold  336 . 
     Each of the tubes  350  of the second layer  332  is a divided tube having a first portion  370  and a second portion  372 . The portions  370 ,  372  are formed substantially parallel to a longitudinal axis of the tubes  350  and arranged so the first portion  370  is positioned upstream of the second portion  372  in respect of the air-flowing direction. Each of the portions  370 ,  372  includes a passage  374  formed therein. The passage  374  formed in the first portion  370  of the tubes  350  fluidly connects a first portion  376  of the first divided manifold  338  and a first portion  377  of the second divided manifold  344 . The first portions  376 ,  377  of the divided manifolds  338 ,  344  and the first portion  370  of the tubes  350  receive the fluid therein. In particular embodiments, the first portion  376  of the first divided manifold  338  is an inlet manifold which distributes the fluid into the first portion  370  of the tubes  350  and the first portion  377  of the second divided manifold  344  is an outlet manifold which collects the fluid from the first portion  370  of the tubes  350 . The passage  374  formed in the second portion  372  of the tubes  350  fluidly connects a second portion  378  of the first divided manifold  338  and a second portion  379  of the second divided manifold  344 . The second portions  378 ,  379  of the divided manifolds  338 ,  344  and the second portion  372  of the tubes  350  include a PCM  380  disposed therein. As shown, a volume of the second portion  378  of the first divided manifold  338  is about one-half a volume of the first portion  376  of the first divided manifold  338 . A volume of the second portion  379  of the second divided manifold  344  is about one-fourth a volume of the first portion  377  of the second divided manifold  344 . 
     Each of the tubes  352  of the third layer  334  is a divided tube having a first portion  381  and a second portion  382 . The portions  381 ,  382  are formed substantially parallel to a longitudinal axis of the tubes  352  and arranged so the first portion  381  is positioned upstream of the second portion  382  in respect of the air-flowing direction. Each of the portions  381 ,  382  includes a passage  384  formed therein. The passage  384  formed in the first portion  381  of the tubes  352  fluidly connects a first portion  386  of the first divided manifold  340  and a first portion  387  of the second divided manifold  346 . The first portions  386 ,  387  of the divided manifolds  340 ,  346  and the first portion  381  of the tubes  352  receive the fluid therein. In particular embodiments, the first portion  386  of the first divided manifold  340  is an inlet manifold which distributes the fluid into the first portion  381  of the tubes  352  and the first portion  387  of the second divided manifold  346  is an outlet manifold which collects the fluid from the first portion  381  of the tubes  352 . The passage  384  formed in the second portion  382  of the tubes  352  fluidly connects a second portion  388  of the first divided manifold  340  and a second portion  389  of the second divided manifold  346 . The second portions  388 ,  389  of the divided manifolds  340 ,  346  and the second portion  382  of the tubes  352  include a PCM  390  disposed therein. As shown, a volume of the second portion  388  of the first divided manifold  340  is about one-half a volume of the first portion  386  of the first divided manifold  340 . A volume of the second portion  389  of the second divided manifold  346  is about one-half a volume of the first portion  387  of the second divided manifold  346 . 
     Each of the PCMs  369 ,  380 ,  390  is any material that melts and solidifies at predetermined temperatures and is capable of storing and releasing thermal energy such as a paraffin wax, an alcohol, water, and any combination thereof, for example. In particular embodiments, the PCMs  369 ,  380 ,  390  are different materials of which the melting point of the PCM  380  is higher than the melting point of the PCM  369  and the melting point of the PCM  390  is higher than the melting points of the PCMs  369 ,  380  so the second layer  332  can further cool the air which has passed through the first layer  330  and the third layer  334  can further cool the air which has passed through the first and second layers  330 ,  332 . It is understood, however, that the PCMs  369 ,  380 ,  390  can be the same material if desired. The PCMs  369 ,  380 ,  390  can also be impregnated with a thermally conductive material such as graphite powder, for example, to further enhance the transfer of thermal energy. 
     An internal web (not shown) similar to the web  104  in  FIG. 3  may be formed in at least one of the second portions  362 ,  372 ,  382  of the tubes  348 ,  350 ,  352 , respectively, to enhance thermal energy conduction from the air flowing through the thermal energy exchanger  326 . Alternatively, at least one of the second portions  362 ,  372 ,  382  of the tubes  348 ,  350 ,  352  can further include a plurality of internal fins (not shown) similar to the fins  89  in  FIG. 2  formed on an inner surface thereof. The internal fins further enhance the transfer of thermal energy of the thermal energy exchanger  326 . 
     The remaining structure of the HVAC system  10  is substantially the same as described above for the embodiments illustrated in  FIGS. 1-5 . 
       FIG. 7  illustrates an alternative configuration of the thermal energy exchanger  426 . In  FIG. 7 , the thermal energy exchanger  426  has a first layer  430 , a second layer  432 , and a third layer  434  arranged substantially perpendicular to an air-flowing direction. Additional or fewer layers than shown can be employed as desired. The layers  430 ,  432 ,  434  are arranged so the second layer  432  is disposed downstream of the first layer  430  and upstream of the third layer  434 . It is understood, however, that the layers  430 ,  432 ,  434  can be arranged as desired. The layers  430 ,  432 ,  434  can be bonded together by any suitable method as desired such as brazing and welding, for example. 
     Each of the layers  430 ,  432 ,  434  of the thermal energy exchanger  426  includes an upper first fluid manifold  436 ,  438 ,  440  and a lower second fluid manifold  442 ,  444 ,  446 , respectively. A plurality of first tubes  448  extends between the fluid manifolds  436 ,  442  of the first layer  430 . A plurality of second tubes  450  extends between the fluid manifolds  438 ,  444  of the second layer  432 . A plurality of third tubes  452  extends between the fluid manifolds  440 ,  446  of the third layer  434 . In certain embodiments, each of the tubes  448 ,  450 ,  452  is provided with louvered fins (not shown) formed thereon. The fins abut an outer surface of the tubes  448 ,  450 ,  452  for enhancing thermal energy transfer of the thermal energy exchanger  426 . 
     As shown, each of the tubes  448  of the first layer  430  is a divided tube having a first portion  460  and a second portion  462 . The portions  460 ,  462  are formed substantially parallel to a longitudinal axis of the tubes  448  and arranged so the first portion  460  is positioned upstream of the second portion  462  in respect of the air-flowing direction. Each of the portions  460 ,  462  includes a passage  464  formed therein. The passage  464  formed in the first portion  460  of the tubes  448  fluidly connects the first fluid manifold  436  and the second fluid manifold  442 . The first portion  460  of the tubes  448  and the fluid manifolds  436 ,  442  receive the fluid therein. In particular embodiments, the first fluid manifold  436  is an inlet manifold which distributes the fluid into the first portion  460  of the tubes  448  and the second fluid manifold  442  is an outlet manifold which collects the fluid from the first portion  460  of the tubes  448 . The passage  464  formed in the second portion  462  of the tubes  448  is closed by a cover  465 . As shown, the second portion  462  of the tubes  448  includes a PCM  469  disposed therein. 
     Each of the tubes  450  of the second layer  432  is a divided tube having a first portion  470  and a second portion  472 . The portions  470 ,  472  are formed substantially parallel to a longitudinal axis of the tubes  450  and arranged so the first portion  470  is positioned upstream of the second portion  472  in respect of the air-flowing direction. Each of the portions  470 ,  472  includes a passage  474  formed therein. The passage  474  formed in the first portion  470  of the tubes  450  fluidly connects the first fluid manifold  438  and the second fluid manifold  444 . The first portion  470  of the tubes  450  and the fluid manifolds  438 ,  444  receive the fluid therein. In particular embodiments, the first fluid manifold  438  is an inlet manifold which distributes the fluid into the first portion  470  of the tubes  450  and the second fluid manifold  444  is an outlet manifold which collects the fluid from the first portion  470  of the tubes  450 . The passage  474  formed in the second portion  472  of the tubes  450  is closed by a cover  475 . The second portion  472  of the tubes  450  include a PCM  479  disposed therein. 
     Each of the tubes  452  of the third layer  434  is a divided tube having a first portion  480  and a second portion  482 . The portions  480 ,  482  are formed substantially parallel to a longitudinal axis of the tubes  452  and arranged so the first portion  480  is positioned upstream of the second portion  482  in respect of the air-flowing direction. Each of the portions  480 ,  482  includes a passage  484  formed therein. The passage  484  formed in the first portion  480  of the tubes  452  fluidly connects the first fluid manifold  440  and the second fluid manifold  446 . The first portion  480  of the tubes  452  and the fluid manifolds  440 ,  446  receive the fluid therein. In particular embodiments, the first fluid manifold  440  is an inlet manifold which distributes the fluid into the first portion  480  of the tubes  452  and the second fluid manifold  446  is an outlet manifold which collects the fluid from the first portion  480  of the tubes  452 . The passage  484  formed in the second portion  482  of the tubes  452  is closed by a cover  485 . The second portion  482  of the tubes  452  include a PCM  489  disposed therein. 
     Each of the PCMs  469 ,  479 ,  489  is any material that melts and solidifies at predetermined temperatures and is capable of storing and releasing thermal energy such as a paraffin wax, an alcohol, water, and any combination thereof, for example. In particular embodiments, the PCMs  469 ,  479 ,  489  are different materials of which the melting point of the PCM  479  is higher than the melting point of the PCM  469  and the melting point of the PCM  489  is higher than the melting points of the PCMs  469 ,  479  so the second layer  432  can further cool the air which has pass through the first layer  430  and the third layer  434  can further cool the air which has passed through the first and second layers  430 ,  432 . It is understood, however, that the PCMs  469 ,  479 ,  489  can be the same material if desired. The PCMs  469 ,  479 ,  489  can also be impregnated with a thermally conductive material such as graphite powder, for example, to further enhance the transfer of thermal energy. 
     An internal web (not shown) similar to the web  104  in  FIG. 3  may be formed in at least one of the second portions  462 ,  472 ,  482  of the tubes  448 ,  450 ,  452 , respectively, to enhance thermal energy conduction from the air flowing through the thermal energy exchanger  426 . Alternatively, at least one of the second portions  462 ,  472 ,  482  of the tubes  448 ,  450 ,  452  can further include a plurality of internal fins (not shown) similar to the fins  89  in  FIG. 2  formed on an inner surface thereof. The internal fins further enhance the transfer of thermal energy of the thermal energy exchanger  426 . 
     The remaining structure of the HVAC system  10  is substantially the same as described above for the embodiments illustrated in  FIGS. 1-6 . 
       FIG. 8  illustrates an alternative configuration of the thermal energy exchanger  26 . In  FIG. 8 , the thermal energy exchanger  526  has a first layer  530 , a second layer  532 , and a third layer  534  arranged substantially perpendicular to an air-flowing direction. Additional or fewer layers than shown can be employed as desired. The layers  530 ,  532 ,  534  are arranged so the second layer  532  is disposed downstream of the first layer  530  and upstream of the third layer  534 . It is understood, however, that the layers  530 ,  532 ,  534  can be arranged as desired. The layers  530 ,  532 ,  534  can be bonded together by any suitable method as desired such as brazing and welding, for example. 
     The first layer  530  of the thermal energy exchanger  526  includes an upper first fluid manifold  536  and a lower second fluid manifold  542 . Each of the layers  532 ,  534  of the thermal energy exchanger  526  includes an upper divided manifold  538 ,  540  and a lower fluid manifold  544 ,  546 , respectively. A plurality of first tubes  548  extends between the manifolds  536 ,  542  of the first layer  530 . A plurality of second tubes  550  extends between the manifolds  538 ,  544  of the second layer  532 . A plurality of third tubes  552  extends between the manifolds  540 ,  546  of the third layer  534 . In certain embodiments, each of the tubes  548 ,  550 ,  552  is provided with louvered fins (not shown) formed thereon. The fins abut an outer surface of the tubes  548 ,  550 ,  552  for enhancing thermal energy transfer of the thermal energy exchanger  526 . 
     As shown, each of the tubes  548  of the first layer  530  includes a passage  564  formed therein. The passage  564  of the tubes  548  fluidly connects the fluid manifolds  536 ,  542  for receiving the fluid therein. In particular embodiments, the first fluid manifold  536  is an inlet manifold which distributes the fluid into the tubes  548  and the second fluid manifold  542  is an outlet manifold which collects the fluid from the tubes  548 . 
     Each of the tubes  550  of the second layer  532  is a divided tube having a first portion  570 , a second portion  572 , and a third portion  573 . The portions  570 ,  572 ,  573  are formed substantially parallel to a longitudinal axis of the tubes  550  and arranged so the second portion  572  is positioned downstream of the first portion  570  and upstream of the third portion  573  in respect of the air-flowing direction. Each of the portions  570 ,  572 ,  573  includes a passage  574  formed therein. The passage  574  formed in the first and third portions  570 ,  573  of the tubes  550  fluidly connects a first and a second portion  576 ,  578 , respectively, of the divided manifold  538  and the fluid manifold  544  to form a U-shaped flow path. The first and second portions  576 ,  578  of the divided manifold  538 , the first and third portions  570 ,  573  of the tubes  550 , and the fluid manifold  544  receive the fluid therein. In particular embodiments, the first portion  576  of the divided manifold  538  is an inlet manifold which distributes the fluid into the first and third portions  570 ,  573  of the tubes  550  and the second portion  578  of the divided manifold  538  is an outlet manifold which collects the fluid from the first and third portions  570 ,  573  of the tubes  550 . The passage  574  formed in the second portion  572  of the tubes  550  is in fluid communication with a third portion  577  of the divided manifold  538 . The second portion  572  of the tubes  550  and the third portion  577  of the divided manifold  538  include a PCM  579  disposed therein. As shown, a volume of the third portion  577  of the first divided manifold  538  is about one-half a combined volume of the first and second portions  576 ,  578  of the first divided manifold  538 . 
     Each of the tubes  552  of the third layer  534  is a divided tube having a first portion  580 , a second portion  582 , and a third portion  583 . The portions  580 ,  582 ,  583  are formed substantially parallel to a longitudinal axis of the tubes  552  and arranged so the second portion  582  is positioned downstream of the first portion  580  and upstream of the third portion  583  in respect of the air-flowing direction. Each of the portions  580 ,  582 ,  583  includes a passage  584  formed therein. The passage  584  formed in the first and third portions  580 ,  583  of the tubes  552  fluidly connects a first and a second portion  586 ,  588 , respectively, of the divided manifold  540  and the fluid manifold  546  to form a U-shaped flow path. The first and second portions  586 ,  588  of the divided manifold  540 , the first and third portions  580 ,  583  of the tubes  552 , and the fluid manifold  546  receive the fluid therein. In particular embodiments, the first portion  586  of the divided manifold  540  is an inlet manifold which distributes the fluid into the first and third portions  580 ,  583  of the tubes  552  and the second portion  588  of the divided manifold  540  is an outlet manifold which collects the fluid from the first and third portions  580 ,  583  of the tubes  552 . The passage  584  formed in the second portion  582  of the tubes  552  is in fluid communication with a third portion  587  of the divided manifold  540 . The second portion  582  of the tubes  552  and the third portion  587  of the divided manifold  540  include a PCM  589  disposed therein. As shown, a volume of the third portion  587  of the first divided manifold  540  is about one-half a combined volume of the first and second portions  586 ,  588  of the first divided manifold  540 . 
     Each of the PCMs  579 ,  589  is any material that melts and solidifies at predetermined temperatures and is capable of storing and releasing thermal energy such as a paraffin wax, an alcohol, water, and any combination thereof, for example. In particular embodiments, the PCMs  579 ,  589  are different materials of which the melting point of the PCM  589  is higher than the melting point of the PCM  579  so the third layer  534  can further cool the air which has passed through the second layer  532 . It is understood, however, that the PCMs  579 ,  589  can be the same material if desired. The PCMs  579 ,  589  can also be impregnated with a thermally conductive material such as graphite powder, for example, to further enhance the transfer of thermal energy. 
     An internal web (not shown) similar to the web  104  in  FIG. 3  may be formed in at least one of the second portions  572 ,  582  of the tubes  550 ,  552 , respectively, to enhance thermal energy conduction from the air flowing through the thermal energy exchanger  526 . Alternatively, at least one of the second portions  572 ,  582  of the tubes  550 ,  552  can further include a plurality of internal fins (not shown) similar to the fins  89  in  FIG. 2  formed on an inner surface thereof. The internal fins further enhance the transfer of thermal energy of the thermal energy exchanger  526 . 
     The remaining structure of the HVAC system  10  is substantially the same as described above for the embodiments illustrated in  FIGS. 1-7 . 
       FIG. 9  illustrates an alternative configuration of the thermal energy exchanger  26 . In  FIG. 9 , the thermal energy exchanger  626  has a first layer  630 , a second layer  632 , and a third layer  634  arranged substantially perpendicular to an air-flowing direction. Additional or fewer layers than shown can be employed as desired. The layers  630 ,  632 ,  634  are arranged so the second layer  632  is disposed downstream of the first layer  630  and upstream of the third layer  634 . It is understood, however, that the layers  630 ,  632 ,  634  can be arranged as desired. The layers  630 ,  632 ,  634  can be bonded together by any suitable method as desired such as brazing and welding, for example. 
     The first layer  630  of the thermal energy exchanger  626  includes an upper fluid manifold  636  and a lower fluid manifold  642 . The second layer  632  of the thermal energy exchanger  626  includes an upper first divided manifold  638  and a lower second divided manifold  644 . The third layer  634  of the thermal energy exchanger  626  includes an upper divided manifold  640  and a lower fluid manifold  646 . A plurality of first tubes  648  extends between the manifolds  636 ,  642  of the first layer  630 . A plurality of second tubes  650  extends between the manifolds  638 ,  644  of the second layer  632 . A plurality of third tubes  652  extends between the manifolds  640 ,  646  of the third layer  634 . In certain embodiments, each of the tubes  648 ,  650 ,  652  is provided with louvered fins (not shown) formed thereon. The fins abut an outer surface of the tubes  648 ,  650 ,  652  for enhancing thermal energy transfer of the thermal energy exchanger  626 . 
     As shown, each of the tubes  648  of the first layer  630  includes a passage  664  formed therein. The passage  664  of the tubes  648  fluidly connects the fluid manifolds  636 ,  642  for receiving the fluid therein. In particular embodiments, the fluid manifold  636  is an inlet manifold which distributes the fluid into the tubes  648  and the fluid manifold  642  is an outlet manifold which collects the fluid from the tubes  648 . 
     Each of the tubes  650  of the second layer  632  is a divided tube having a first portion  670 , a second portion  672 , and a third portion  673 . The portions  670 ,  672 ,  673  are formed substantially parallel to a longitudinal axis of the tubes  650  and arranged so the second portion  672  is positioned downstream of the first portion  670  and upstream of the third portion  673  in respect of the air-flowing direction. Each of the portions  670 ,  672 ,  673  includes a passage  674  formed therein. The passage  674  formed in the first and third portions  670 ,  673  of the tubes  650  fluidly connects a first portion  675  of the first divided manifold  638  and a first portion  676  of the second divided manifold  644  to form a pair of parallel flow paths. The first portions  675 ,  676  of the divided manifolds  638 ,  644  and the first and third portions  670 ,  673  of the tubes  650  receive the fluid therein. In particular embodiments, the first portion  675  of the first divided manifold  638  is an inlet manifold which distributes the fluid into the first and third portions  670 ,  673  of the tubes  650  and the first portion  676  of the second divided manifold  644  is an outlet manifold which collects the fluid from the first and third portions  670 ,  673  of the tubes  650 . The passage  674  formed in the second portion  672  of the tubes  650  fluidly connects a second portion  677  of the first divided manifold  638  and a first portion  678  of the second divided manifold  644 . The second portion  672  of the tubes  650  and the second portions  677 ,  678  of the divided manifolds  638 ,  644  include a PCM  679  disposed therein. As shown, a volume of the second portion  677  of the first divided manifold  638  is about one-half a volume of the first portion  675  of the first divided manifold  638 . A volume of the second portion  678  of the second divided manifold  644  is about one-half a volume of the first portion  676  of the second divided manifold  644 . 
     Each of the tubes  652  of the third layer  634  is a divided tube having a first portion  680 , a second portion  682 , and a third portion  683 . The portions  680 ,  682 ,  683  are formed substantially parallel to a longitudinal axis of the tubes  652  and arranged so the second portion  682  is positioned downstream of the first portion  680  and upstream of the third portion  683  in respect of the air-flowing direction. Each of the portions  680 ,  682 ,  683  includes a passage  684  formed therein. The passage  684  formed in the first and third portions  680 ,  683  of the tubes  652  fluidly connects a first and a second portion  686 ,  688 , respectively, of the divided manifold  640  and the fluid manifold  646  to form a U-shaped flow path. The first and second portions  686 ,  688  of the divided manifold  640 , the first and third portions  680 ,  683  of the tubes  652 , and the fluid manifold  646  receive the fluid therein. In particular embodiments, the first portion  686  of the divided manifold  640  is an inlet manifold which distributes the fluid into the first and third portions  680 ,  683  of the tubes  652  and the second portion  688  of the divided manifold  640  is an outlet manifold which collects the fluid from the first and third portions  680 ,  683  of the tubes  652 . The passage  684  formed in the second portion  682  of the tubes  652  is in fluid communication with a third portion  687  of the divided manifold  640 . The second portion  682  of the tubes  652  and the third portion  687  of the divided manifold  640  include a PCM  689  disposed therein. 
     Each of the PCMs  679 ,  689  is any material that melts and solidifies at predetermined temperatures and is capable of storing and releasing thermal energy such as a paraffin wax, an alcohol, water, and any combination thereof, for example. In particular embodiments, the PCMs  679 ,  689  are different materials of which the melting point of the PCM  689  is higher than the melting point of the PCM  679  so the third layer  634  can further cool the air which has passed through the second layer  632 . It is understood, however, that the PCMs  679 ,  689  can be the same material if desired. The PCMs  679 ,  689  can also be impregnated with a thermally conductive material such as graphite powder, for example, to further enhance the transfer of thermal energy. 
     An internal web (not shown) similar to the web  104  in  FIG. 3  may be formed in at least one of the second portions  672 ,  682  of the tubes  650 ,  652 , respectively, to enhance thermal energy conduction from the air flowing through the thermal energy exchanger  626 . Alternatively, at least one of the second portions  672 ,  682  of the tubes  650 ,  652  can further include a plurality of internal fins (not shown) similar to the fins  89  in  FIG. 2  formed on an inner surface thereof. The internal fins further enhance the transfer of thermal energy of the thermal energy exchanger  626 . 
     The remaining structure of the HVAC system  10  is substantially the same as described above for the embodiments illustrated in  FIGS. 1-8 . 
       FIG. 10  illustrates an alternative configuration of the thermal energy exchanger  26 . In  FIG. 10 , the thermal energy exchanger  726  has a first layer  730 , a second layer  732 , and a third layer  734  arranged substantially perpendicular to an air-flowing direction. Additional or fewer layers than shown can be employed as desired. The layers  730 ,  732 ,  734  are arranged so the second layer  732  is disposed downstream of the first layer  730  and upstream of the third layer  734 . It is understood, however, that the layers  730 ,  732 ,  734  can be arranged as desired. The layers  730 ,  732 ,  734  can be bonded together by any suitable method as desired such as brazing and welding, for example. 
     The first layer  730  of the thermal energy exchanger  726  includes an upper fluid manifold  738  and a lower fluid manifold  739 . The second layer  732  of the thermal energy exchanger  726  includes an upper divided manifold  740  and a lower divided manifold  741 . The third layer  734  of the thermal energy exchanger  726  includes a pair of upper fluid manifolds  742 ,  743  and a lower fluid manifold  744 . A plurality of first tubes  746  extends between the manifolds  738 ,  739  of the first layer  730 . A plurality of second tubes  748  extends between the manifolds  740 ,  741  of the second layer  732 . A plurality of third tubes  750  extends between the manifolds  742 ,  743 ,  744  of the third layer  734 . In certain embodiments, each of the tubes  746 ,  748 ,  750  is provided with louvered fins (not shown) formed thereon. The fins abut an outer surface of the tubes  746 ,  748 ,  750  for enhancing thermal energy transfer of the thermal energy exchanger  726 . 
     As shown, each of the tubes  746  of the first layer  730  includes a passage  757  formed therein. The passage  757  formed in the tubes  746  fluidly connects the fluid manifolds  738 ,  739  for receiving the fluid therein. In particular embodiments, the fluid manifold  738  is an inlet manifold which distributes the fluid into the tubes  746 , and the fluid manifold  739  is an outlet manifold which collects the fluid from the tubes  746 . 
     Each of the tubes  748  of the second layer  732  is a divided tube having a first portion  770 , a second portion  772 , and a third portion  773 . The portions  770 ,  772 ,  773  are formed substantially parallel to a longitudinal axis of the tubes  748  and arranged so the second portion  772  is positioned downstream of the first portion  770  and upstream of the third portion  773  in respect of the air-flowing direction. Each of the portions  770 ,  772 ,  773  includes a passage  774  formed therein. The passage  774  formed in the first and third portions  770 ,  773  of the tubes  748  fluidly connects a first portion  775  of the first divided manifold  740  and a first portion  776  of the second divided manifold  741  to form a pair of parallel flow paths. The first portions  775 ,  776  of the divided manifolds  740 ,  741  and the first and third portions  770 ,  773  of the tubes  748  receive the fluid therein. In particular embodiments, the first portion  775  of the first divided manifold  740  is an inlet manifold which distributes the fluid into the first and third portions  770 ,  773  of the tubes  748  and the first portion  776  of the second divided manifold  741  is an outlet manifold which collects the fluid from the first and third portions  770 ,  773  of the tubes  748 . The passage  774  formed in the second portion  772  of the tubes  748  fluidly connects a second portion  777  of the first divided manifold  740  and a first portion  778  of the second divided manifold  741 . The second portion  772  of the tubes  748  and the second portions  777 ,  778  of the divided manifolds  740 ,  741  include a PCM  779  disposed therein. As shown, a volume of the second portion  777  of the first divided manifold  740  is about one-half a volume of the first portion  775  of the first divided manifold  740 . A volume of the second portion  778  of the second divided manifold  741  is about one-half a volume of the first portion  776  of the second divided manifold  741 . 
     Each of the tubes  750  of the third layer  734  is a divided tube having a first portion  780 , a second portion  782 , and a third portion  783 . The portions  780 ,  782 ,  783  are formed substantially parallel to a longitudinal axis of the tubes  750  and arranged so the second portion  782  is positioned downstream of the first portion  780  and upstream of the third portion  783  in respect of the air-flowing direction. Each of the portions  780 ,  782 ,  783  includes a passage  784  formed therein. The passage  784  formed in the first and third portions  780 ,  783  of the tubes  750  fluidly connects the fluid manifolds  742 ,  743 ,  744  to form a U-shaped flow path. The fluid manifolds  742 ,  743 ,  744  and the first and third portions  780 ,  783  of the tubes  750  receive the fluid therein. In particular embodiments, the fluid manifold  742  is an inlet manifold which distributes the fluid into the first and third portions  780 ,  783  of the tubes  750 , and the fluid manifold  743  is an outlet manifold which collects the fluid from the first and third portions  780 ,  783  of the tubes  750 . The passage  784  formed in the second portion  782  of the tubes  750  is closed by a cover  785 . The second portion  782  of the tubes  750  include a PCM  787  disposed therein. 
     Each of the PCMs  779 ,  787  is any material that melts and solidifies at predetermined temperatures and is capable of storing and releasing thermal energy such as a paraffin wax, an alcohol, water, and any combination thereof, for example. In particular embodiments, the PCMs  779 ,  787  are different materials of which the melting point of the PCM  787  is higher than the melting point of the PCM  779  so the third layer  734  can further cool the air which has passed through the second layer  732 . It is understood, however, that the PCMs  779 ,  787  can be the same material if desired. The PCMs  779 ,  787  can also be impregnated with a thermally conductive material such as graphite powder, for example, to further enhance the transfer of thermal energy. 
     An internal web (not shown) similar to the web  104  in  FIG. 3  may be formed in at least one of the second portions  772 ,  782  of the tubes  748 ,  750 , respectively, to enhance thermal energy conduction from the air flowing through the thermal energy exchanger  726 . Alternatively, at least one of the second portions  772 ,  782  of the tubes  748 ,  750 , can further include a plurality of internal fins (not shown) similar to the fins  89  in  FIG. 2  formed on an inner surface thereof. The internal fins further enhance the transfer of thermal energy of the thermal energy exchanger  726 . 
     The remaining structure of the HVAC system  10  is substantially the same as described above for the embodiments illustrated in  FIGS. 1-9   
       FIG. 11  illustrates an alternative configuration of the thermal energy exchanger  26 . In  FIG. 11 , the thermal energy exchanger  826  has a first layer  830 , a second layer  832 , and a third layer  834  arranged substantially perpendicular to an air-flowing direction. Additional or fewer layers than shown can be employed as desired. The layers  830 ,  832 ,  834  are arranged so the second layer  832  is disposed downstream of the first layer  830  and upstream of the third layer  834 . It is understood, however, that the layers  830 ,  832 ,  834  can be arranged as desired. The layers  830 ,  832 ,  834  can be bonded together by any suitable method as desired such as brazing and welding, for example. 
     The first layer  830  includes an upper first fluid manifold  836  and a lower second fluid manifold  842 . Each of the layers  832 ,  834  of the thermal energy exchanger  826  includes a divided manifold  838 ,  840  and a fluid manifold  844 ,  846 , respectively. A plurality of first tubes  848  extends between the manifolds  836 ,  842  of the first layer  830 . A plurality of second tubes  850  extends between the manifolds  838 ,  844  of the second layer  832 . A plurality of third tubes  852  extends between the manifolds  840 ,  846  of the third layer  834 . In certain embodiments, each of the tubes  848 ,  850 ,  852  is provided with louvered fins (not shown) formed thereon. The fins abut an outer surface of the tubes  848 ,  850 ,  852  for enhancing thermal energy transfer of the thermal energy exchanger  826 . 
     As shown, each of the tubes  848  of the first layer  830  includes a passage  858  formed therein. The passage  858  formed in the tubes  848  fluidly connects the fluid manifolds  836 ,  842  for receiving the fluid therein. In particular embodiments, the first fluid manifold  836  is an inlet manifold which distributes the fluid into the tubes  848  and the second fluid manifold  842  is an outlet manifold which collects the fluid from the tubes  848 . 
     Each of the tubes  850  of the second layer  832  is a divided tube having a first portion  873 , a second portion  874 , a third portion  875 , a fourth portion  876 , and a fifth portion  877 . The portions  873 ,  874 ,  875 ,  876 ,  877  are formed substantially parallel to a longitudinal axis of the tubes  850  and arranged so the second portion  874  is positioned downstream of the first portion  873 , the third portion  875  is positioned downstream of the second portion  874 , the fourth portion  876  is disposed downstream of the third portion  875 , and the fifth portion  877  is disposed downstream of the fourth portion  876  in respect of the air-flowing direction. 
     Each of the portions  873 ,  874 ,  875 ,  876 ,  877  includes a passage  878  formed therein. The passage  878  formed in the first, third, and fifth portions  873 ,  875 ,  877  of the tubes  850  fluidly connects a first and a second portion  880 ,  881 , respectively, of the divided manifold  838  and the fluid manifold  844  to form a flow path having a substantially serpentine-like shape. The first and second portions  880 ,  881  of the divided manifold  838 , the first, third, and fifth portions  873 ,  875 ,  877  of the tubes  850 , and the fluid manifold  844  receive the fluid therein. In particular embodiments, the first portion  880  of the divided manifold  838  is an inlet manifold which distributes the fluid into the first, third, and fifth portions  873 ,  875 ,  877  of the tubes  850  and the fluid manifold  844  is an outlet manifold which collects the fluid from the first, third, and fifth portions  873 ,  875 ,  877  of the tubes  850 . The passage  878  formed in the second and fourth portions  874 ,  876  of the tubes  850  is in fluid communication with a third and a fourth portion  882 ,  884  of the divided manifold  838 . The second and fourth portions  874 ,  876  of the tubes  850  and the second and fourth portions  882 ,  884  of the divided manifold  838  include a PCM  885  disposed therein. As shown, a volume of the second and fourth portions  882 ,  884  of the divided manifold  838  is about two-thirds a combined volume of the first and second portions  880 ,  881  of the divided manifold  838 . 
     Each of the tubes  852  of the third layer  834  is a divided tube having a first portion  888 , a second portion  889 , a third portion  890 , a fourth portion  891 , and a fifth portion  892 . The portions  888 ,  889 ,  890 ,  891 ,  892  are formed substantially parallel to a longitudinal axis of the tubes  852  and arranged so the second portion  889  is positioned downstream of the first portion  888 , the third portion  890  is positioned downstream of the second portion  889 , the fourth portion  891  is disposed downstream of the third portion  890 , and the fifth portion  892  is disposed downstream of the fourth portion  891  in respect of the air-flowing direction. 
     Each of the portions  888 ,  889 ,  890 ,  891 ,  892  includes a passage  893  formed therein. The passage  893  formed in the first, third, and fifth portions  888 ,  890 ,  892  of the tubes  852  fluidly connects a first and a second portion  894 ,  895 , respectively, of the divided manifold  840  and the fluid manifold  846  to form a flow path having a substantially serpentine-like shape. The first and second portions  894 ,  895  of the divided manifold  840 , the first, third, and fifth portions  888 ,  890 ,  892  of the tubes  852 , and the fluid manifold  846  receive the fluid therein. In particular embodiments, the first portion  894  of the divided manifold  840  is an inlet manifold which distributes the fluid into the first, third, and fifth portions  888 ,  890 ,  892  of the tubes  852  and the fluid manifold  846  is an outlet manifold which collects the fluid from the first, third, and fifth portions  888 ,  890 ,  892  of the tubes  852 . The passage  893  formed in the second and fourth portions  889 ,  891  of the tubes  852  is in fluid communication with a third and a fourth portion  896 ,  897  of the divided manifold  840 . The second and fourth portions  889 ,  891  of the tubes  852  and the second and fourth portions  896 ,  897  of the divided manifold  840  include a PCM  899  disposed therein. As shown, a volume of the second and fourth portions  896 ,  897  of the divided manifold  840  is about two-thirds a combined volume of the first and second portions  894 ,  895  of the divided manifold  840 . 
     Each of the PCMs  885 ,  899  is any material that melts and solidifies at predetermined temperatures and is capable of storing and releasing thermal energy such as a paraffin wax, an alcohol, water, and any combination thereof, for example. In particular embodiments, the PCMs  885 ,  899  are different materials of which the melting point of the PCM  899  is higher than the melting point of the PCM  885  so the third layer  834  can further cool the air which has passed through the second layer  832 . It is understood, however, that the PCMs  885 ,  899  can be the same material if desired. The PCMs  885 ,  899  can also be impregnated with a thermally conductive material such as graphite powder, for example, to further enhance the transfer of thermal energy. 
     An internal web (not shown) similar to the web  104  in  FIG. 3  may be formed in at least one of the second portions  874 ,  889  and the fourth portions  876 ,  891  of the tubes  850 ,  852 , respectively, to enhance thermal energy conduction from the air flowing through the thermal energy exchanger  826 . Alternatively, at least one of the second portions  874 ,  889  and the fourth portions  876 ,  891  of the tubes  850 ,  852 , respectively, can further include a plurality of internal fins (not shown) similar to the fins  89  in  FIG. 2  formed on an inner surface thereof. The internal fins further enhance the transfer of thermal energy of the thermal energy exchanger  826 . 
     The remaining structure of the HVAC system  10  is substantially the same as described above for the embodiments illustrated in  FIGS. 1-10 . 
       FIG. 12  illustrates an alternative configuration of the thermal energy exchanger  26 . In  FIG. 12 , the thermal energy exchanger  926  includes at least one layer  928  maximizing thermal energy storage capacity. The layer  928  of the thermal energy exchanger  926  includes a plurality of tubes  930 . Each of the tubes  930  is provided with louvered fins  932  formed thereon. The fins  932  abut an outer surface of the tubes  930  for enhancing thermal energy transfer of the thermal energy exchanger  926 . The fins  932  include a plurality of crests  934  formed thereon. The crests  934  are formed substantially parallel to each other and at a substantially 90 degree angle to the tubes  930 . It is understood that the crests  934  can be formed at any angle to the tubes  930  if desired. Each of the crests  934  defines an air space  936  extending between the tubes  930  and the fins  932 . It is understood that the thermal energy exchanger  926  can be constructed as a finless heat exchanger if desired. 
     Each of the tubes  930  further includes a passage  938  formed therein. The passage  938  fluidly connects the tubes  930  with an upper fluid manifold  940  and a lower fluid manifold (not shown). The tubes  930 , the upper fluid manifold  940 , and the lower fluid manifold receive the fluid therein. As illustrated, a PCM manifold  942  is formed around at least a portion of an outer periphery of the tubes  930  and the fins  932 . The tubes  930  extend through the PCM manifold  942  and between the upper fluid manifold  940  and the lower fluid manifold. A secondary PCM manifold  944  can be formed in at least one of the upper fluid manifold  940  and the lower fluid manifold if desired. The PCM manifolds  942 ,  944  include a PCM  946  disposed therein. The PCM manifolds  942 ,  944  are sealed to militate against leakage of the PCM  946  in the fluid. The PCM manifolds  942 ,  944  are filled by heating the PCM  946  above a melting point thereof until the PCM  946  is a liquid which can be easily poured into an opening (not shown) of the PCM manifolds  942 ,  944 . The PCM  946  absorbs thermal energy from the air flowing through the thermal energy exchanger  926  when the fuel-powered engine is not in operation. Accordingly, when the fuel-powered engine of the vehicle is in operation, the PCM  946  releases thermal energy into conditioned air from the evaporator  24  flowing therethrough. 
     The remaining structure of the thermal energy exchanger  926  and the HVAC system  10  is substantially the same as described above for the embodiments illustrated in  FIGS. 1-11 . 
       FIG. 13  illustrates an alternative configuration of the thermal energy exchanger  26 . In  FIG. 13 , the thermal energy exchanger  1026  includes at least one layer  1028  maximizing thermal energy storage capacity. The layer  1028  of the thermal energy exchanger  1026  includes a plurality of tubes  1030 . Each of the tubes  1030  is provided with louvered fins  1032  formed thereon. The fins  1032  abut an outer surface of the tubes  1030  for enhancing thermal energy transfer of the thermal energy exchanger  1026 . The fins  1032  include a plurality of crests  1034  formed thereon. The crests  1034  are formed substantially parallel to each other and at a substantially 90 degree angle to the tubes  1030 . It is understood that the crests  1034  can be formed at any angle to the tubes  1030  if desired. Each of the crests  1034  defines an air space  1036  extending between the tubes  1030  and the fins  1032 . It is understood that the thermal energy exchanger  1026  can be constructed as a finless heat exchanger if desired. 
     Each of the tubes  1030  further includes a passage  1038  formed therein. The passage  1038  fluidly connects the tubes  1030  with an upper fluid manifold  1040  and a lower fluid manifold (not shown). The tubes  1030 , the upper fluid manifold  1040 , and the lower fluid manifold receive the fluid therein. As illustrated, a PCM manifold  1042  is formed around at least a portion of an outer periphery of the tubes  1030  and the fins  1032 . The tubes  1030  extend through the PCM manifold  1042  and between the upper fluid manifold  1040  and the lower fluid manifold. A secondary PCM manifold  1044  can be formed adjacent an outer surface  1045  of at least one of the upper fluid manifold  1040  and the lower fluid manifold if desired. The PCM manifolds  1042 ,  1044  include a PCM  1046  disposed therein. The PCM manifolds  1042 ,  1044  are sealed to militate against leakage of the PCM  1046  in the fluid. The PCM manifolds  1042 ,  1044  are filled by heating the PCM  1046  above a melting point thereof until the PCM  1046  is a liquid which can be easily poured into an opening (not shown) of the PCM manifolds  1042 ,  1044 . The PCM  1046  absorbs thermal energy from the air flowing through the thermal energy exchanger  1026  when the fuel-powered engine is not in operation. Accordingly, when the fuel-powered engine of the vehicle is in operation, the PCM  1046  releases thermal energy into conditioned air from the evaporator  24  flowing therethrough. 
     The remaining structure of the thermal energy exchanger  1026  and the HVAC system  10  is substantially the same as described above for the embodiments illustrated in  FIGS. 1-12 . 
       FIG. 14  illustrates an alternative configuration of the thermal energy exchanger  26 . In  FIG. 14 , the thermal energy exchanger  1126  includes at least one layer  1128  maximizing thermal energy storage capacity. The layer  1128  of the thermal energy exchanger  1126  includes a plurality of tubes  1130 . Each of the tubes  1130  is provided with louvered fins  1132  formed thereon. The fins  1132  abut an outer surface of the tubes  1130  for enhancing thermal energy transfer of the thermal energy exchanger  1126 . The fins  1132  include a plurality of crests  1134  formed thereon. The crests  1134  are formed substantially parallel to each other and at substantially 90 degree angle to the tubes  1130 . It is understood that the crests  1134  can be formed at any angle to the tubes  1130  if desired. Each of the crests  1134  defines an air space  1136  extending between the tubes  1130  and the fins  1132 . It is understood that the thermal energy exchanger  1126  can be constructed as a finless heat exchanger if desired. 
     Each of the tubes  1130  further includes a passage  1138  formed therein. The passage  1138  fluidly connects the tubes  1130  with an upper fluid manifold  1140  and a lower fluid manifold (not shown). The tubes  1130 , the upper fluid manifold  1140 , and the lower fluid manifold receive the fluid therein. As illustrated, a PCM manifold  1142  is formed around at least a portion of an outer periphery of the tubes  1130  and the fins  1132 . The tubes  1130  extend through the PCM manifold  1142  and between the upper fluid manifold  1140  and the lower fluid manifold. A secondary PCM manifold  1144  is formed around an outer periphery of the thermal energy exchanger  1126 . As shown, the PCM manifolds  1142 ,  1144  can be integrally formed if desired. The PCM manifolds  1142 ,  1144  include a PCM  1146  disposed therein. The PCM manifolds  1142 ,  1144  are sealed to militate against leakage of the PCM  1146  into the fluid of from the thermal energy exchanger  1126 . The PCM manifolds  1142 ,  1144  are filled by heating the PCM  1146  above a melting point thereof until the PCM  1146  is a liquid which can be easily poured into an opening (not shown) of the PCM manifolds  1142 ,  1144 . The PCM  1146  absorbs thermal energy from the air flowing through the thermal energy exchanger  1126  when the fuel-powered engine is not in operation. Accordingly, when the fuel-powered engine of the vehicle is in operation, the PCM  1146  releases thermal energy into conditioned air from the evaporator  24  flowing therethrough. 
     The remaining structure of the thermal energy exchanger  1126  and the HVAC system  10  is substantially the same as described above for the embodiments illustrated in  FIGS. 1-13 . 
       FIG. 15  illustrates an alternative configuration of the thermal energy exchanger  26 . In  FIG. 15 , the thermal energy exchanger  1226  includes at least one layer  1228  maximizing thermal energy storage capacity. The layer  1228  of the thermal energy exchanger  1226  includes a plurality of first tubes  1230  a plurality of second tubes  1231 . Each of the tubes  1230  is provided with louvered fins  1232  formed thereon. The fins  1232  abut an outer surface of the tubes  1230  for enhancing thermal energy transfer of the thermal energy exchanger  1226 . The fins  1232  include a plurality of crests  1234  formed thereon. The crests  1234  are formed substantially parallel to each other and at a substantially 90 degree angle to the tubes  1230 . It is understood that the crests  1234  can be formed at any angle to the tubes  1230  if desired. Each of the crests  1234  defines an air space  1236  extending between the tubes  1230  and the fins  1232 . It is understood that the thermal energy exchanger  1226  can be constructed as a finless heat exchanger if desired. 
     Each of the tubes  1230 ,  1231  further include a passage  1238  formed therein. The tubes  1230  and the tubes  1231  are arranged in an alternating pattern. The passage  1238  of the tubes  1230  fluidly connects the tubes  1230  with an upper fluid manifold  1240  and a lower fluid manifold (not shown). The tubes  1230 , the upper fluid manifold  1240 , and the lower fluid manifold receive the fluid therein. The passage  1238  formed in each of the tubes  1231  is in fluid communication with a respective PCM manifold  1242 . Each of the PCM manifolds  1242  extends between a pair of the tubes  1230 . A secondary PCM manifold  1244  is formed around at least a portion of an outer periphery of the thermal energy exchanger  1226 . In certain embodiments, the PCM manifold  1244  is formed around an entire outer periphery of the thermal energy exchanger  1226  if desired. As shown, at least one of the PCM manifolds  1242  and the PCM manifold  1244  can be integrally formed if desired. The tubes  1231  and the PCM manifolds  1242 ,  1244  include a PCM  1246  disposed therein. The PCM manifolds  1242 ,  1244  are sealed to militate against leakage of the PCM  1246  into the fluid or from the thermal energy exchanger  1226 . The PCM manifolds  1242 ,  1244  are filled by heating the PCM  1246  above a melting point thereof until the PCM  1246  is a liquid which can be easily poured into an opening (not shown) of the PCM manifolds  1242 ,  1244 . The PCM  1246  absorbs thermal energy from the air flowing through the thermal energy exchanger  1226  when the fuel-powered engine is not in operation. Accordingly, when the fuel-powered engine of the vehicle is in operation, the PCM  1246  releases thermal energy into conditioned air from the evaporator  24  flowing therethrough. 
     The remaining structure of the thermal energy exchanger  1226  and the HVAC system  10  is substantially the same as described above for the embodiments illustrated in  FIGS. 1-14 . 
     It is understood that the operation of the HVAC system  10  including the thermal energy exchanger  26  is substantially similar to the operation of the HVAC system  10  including the alternate configurations of the thermal energy exchangers  126 ,  226 ,  326 ,  426 ,  526 ,  626 ,  726 ,  826 ,  926 ,  1026 ,  1126 ,  1226 . Accordingly, for simplicity, only the operation of the HVAC system  10  including the thermal energy exchanger  26  is described hereinafter. 
     In operation, the HVAC system  10  conditions air by heating or cooling the air, and providing the conditioned air to the passenger compartment of the vehicle. Air flows through the housing  14  of the module  12 . Air from the supply of air is received in the inlet section  16  of the housing  14  in the air inlet  22 . 
     When the fuel-powered engine of the vehicle is in operation, the fluid from the source of cooled fluid  30  circulates through the conduit  36 . Accordingly, the fluid circulates through the evaporator core  24 , as shown in  FIG. 1 . The air from the inlet section  16  flows into the evaporator core  24  where the air is cooled to a desired temperature by a transfer of thermal energy from the air to the fluid from the source of cooled fluid  30 . The conditioned air stream then exits the evaporator core  24 . When the HVAC system  10  is not operating in the pull-down mode, the air from the evaporator core  24  is selectively permitted by the blend door  50  to flow into the thermal energy exchanger  26 . 
     In the thermal energy exchanger  26 , the conditioned air flows through the air spaces  88  defined by the louvered fins  84  and the tubes  78 ,  80 ,  82  of the thermal energy exchanger  26 . The conditioned air absorbs thermal energy from the PCM  94  disposed in the tubes  80  and the PCM  100  disposed in the tubes  82 . The transfer of thermal energy from the PCMs  94 ,  100  to the conditioned air cools and solidifies the PCMs  94 ,  100 . It is understood that the fluid from the source of cooled fluid  30  can also circulate through the conduit  38  and the thermal energy exchanger  26 . The fluid flows from the source of cooled fluid  30  through the tubes  78 , set A of tubes  80 , and set C of tubes  82  to absorb thermal energy from the PCMs  94 ,  100  disposed in set B of tubes  80  and set C of tubes  82 , respectively. Accordingly, the transfer of thermal energy to the fluid further cools and solidifies the PCMs  94 ,  100 . 
     When the fuel-powered engine of the vehicle is not in operation, the fluid from the source of cooled fluid  30  does not circulate through the conduits  36 ,  38 . Accordingly, the fluid does not circulate through the evaporator core  24  or the thermal energy exchanger  26 . The air from the inlet section  16  flows into and through the evaporator core  24  where a temperature thereof is unchanged. The air stream then exits the evaporator core  24  and is selectively permitted by the blend door  50  to flow into the thermal energy exchanger  26 . 
     In the thermal energy exchanger  26 , the air flows through the air spaces  88  defined by the louvered fins  84  and the tubes  78 ,  80 ,  82  of the thermal energy exchanger  26 . The air is cooled to a desired temperature by a transfer of thermal energy from the PCMs  94 ,  100  disposed in set B of tubes  80  and set C of tubes  82 , respectively, to the air. Accordingly, the PCMs  94 ,  100  are caused to melt. The conditioned cooled air then exits the thermal energy exchanger  26  and flows through the heater core  28  and into the outlet and distribution section. 
     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.