Abstract:
This invention is directed to a heat exchanger that exchanges heat between a first fluid, a second fluid, and a phase change material (PCM). Both tubes and header tanks contain phase change material. The phase change material header tanks are advantageously located outside of the first fluid&#39;s header tanks.

Description:
FIELD OF THE INVENTION 
     The invention relates to a climate control system for a vehicle and more particularly to a thermal energy exchanger for a heating, ventilating, and air conditioning system. 
     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 main housing having a hollow interior; a plurality of first tubes disposed in the housing forming open areas therebetween, wherein at least one of the first tubes receives a first fluid therein; and a plurality of second tubes disposed in the housing, the second tubes interleaved with the first tubes, wherein at least a portion of at least one of the second tubes includes a phase change material disposed therein. 
     In another embodiment, the thermal energy exchanger for a heating, ventilating, and air conditioning system comprises a hollow main housing including a first inlet and a first outlet, wherein the first inlet and the first outlet are in fluid communication with a source of cooled fluid, the housing further including a second inlet and a second outlet, wherein the second inlet and the second outlet are in fluid communication with a heat exchanger disposed in a control module of a heating, ventilating, and air conditioning system; a plurality of first tubes disposed in the housing forming open areas therebetween, wherein at least one of the first tubes receives a first fluid from the source of cooled fluid therein and the open areas receive a second fluid from the heat exchanger therein; and a plurality of second tubes disposed in the housing, wherein at least one of the second tubes includes a phase change material disposed therein. 
     In another embodiment, the thermal energy exchanger for a heating, ventilating, and air conditioning system comprises a hollow main housing including a first inlet and a first outlet, wherein the first inlet and the first outlet are in fluid communication with a source of cooled fluid, the housing further including a second inlet and a second outlet, wherein the second inlet and the second outlet are in fluid communication with a heat exchanger disposed in a control module of the heating, ventilating, and air conditioning system; a plurality of first tubes disposed in the housing fluidly connecting the first inlet and the first outlet, wherein the first tubes form open areas therebetween, the open areas fluidly connecting the second inlet and the second outlet, wherein at least one of the first tubes receives a first fluid from the source of cooled fluid therein and the open areas receive a second fluid from the heat exchanger therein; and a plurality of second tubes disposed in the housing, wherein at least one of the second tubes surrounds alternating first tubes forming a space therebetween, wherein the space 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 fragmentary schematic flow diagram of an HVAC system including a schematic cross-sectional view of a thermal energy exchanger having a phase change material disposed therein according to an embodiment of the invention; 
         FIG. 2  is a fragmentary schematic cross-sectional elevational view of a thermal energy exchanger having a phase change material disposed therein according to another embodiment of the invention; and 
         FIG. 3  is a fragmentary schematic cross-sectional elevational view of a thermal energy exchanger having a phase change material disposed therein according to another embodiment of the invention. 
     
    
    
     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 , and at least one of a heat exchanger  26  and a heater core  28  therein. In the embodiment shown, the heat exchanger  26  and the heater core  28  are disposed downstream of a blend door  29 . The blend door  29  is adapted to selectively permit a flow of air through the heat exchanger  26  and the heater core  28  when the HVAC system  10  is not operating in a pull-down mode. 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 evaporator core  24  is adapted to absorb thermal energy and cool the air flowing therethrough when a fuel-powered engine of the vehicle is in operation. 
     The heat exchanger  26  is in fluid communication with a thermal energy exchanger  38  through a conduit  40 . The conduit  40  includes a pump  42  and a valve  44  disposed therein. The pump  42  is adapted to cause a fluid (not shown) disposed therein to circulate through the conduit  40 . The valve  44  selectively militates against a flow of the fluid therethrough. It is understood that the fluid can be any conventional fluid such as an engine coolant, for example. The fluid is adapted to absorb thermal energy and cool the air flowing through the heat exchanger  26  when the fuel-powered engine of the vehicle is not in operation. 
     The thermal energy exchanger  38  is also in fluid communication with the source of cooled fluid  30  through a conduit  46 . The conduit  46  can include a valve  48  disposed therein to selectively militate against a flow of the cooled fluid therethrough. 
     The heater core  28  is in fluid communication with a source of heated fluid  50  through a conduit  52 . The source of heated fluid  50  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  54  may be disposed in the conduit  52  to selectively militate against a flow of the 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. It is understood that the source of heated fluid  50  can be in fluid communication with the heat exchanger  26  as desired without departing from the scope and spirit of the invention. 
     In the embodiment shown, the thermal energy exchanger  38  has a cross-flow configuration and includes a main housing  60  having a hollow interior. The main housing  60  may be made of conventional materials such as polypropylene, for example. In the embodiment shown, the main housing  60  is generally rectangular in shape. It is understood that the main housing  60  can have other shapes as desired such as cylindrical, for example. The main housing  60  includes a first inlet  64 , a second inlet  66 , a first outlet  68 , and a second outlet  70  formed therein. The inlets  64 ,  66  and the outlets  68 ,  70  are formed to extend laterally outwardly from the main housing  60 . The first inlet  64  and the first outlet  68  are in fluid communication with the source of cooled fluid  30  through the conduit  46 . The second inlet  66  and the second outlet  70  are in fluid communication with the heat exchanger  26  through the conduit  40 . An insulating material (not shown) can be disposed on an outer surface of the main housing  60  to militate against a dissipation of thermal energy therefrom. 
     The first inlet  64  and the first outlet  68  are fluidly connected by an inlet first manifold  72 , an outlet second manifold  73 , and a plurality of first tubes  74  extending therebetween. The manifolds  72 ,  73  and the first tubes  74  are disposed in the hollow interior of the thermal energy exchanger  38  and receive the fluid from the source of cooled fluid  30  therethrough. The manifolds  72 ,  73  are formed on opposite sides of the housing  60  substantially parallel to a flow of the fluid from the source of the cooled fluid  30  into the first inlet  64  and from the first outlet  68 . 
     The first tubes  74  are substantially parallel in relation to each other and are spaced apart to define a series of open areas  78  therebetween. The flow of the fluid through the first tubes  74  is substantially perpendicular to the flow of the fluid from the source of the cooled fluid  30  through the first inlet  64 , the first outlet  68 , and the manifolds  72 ,  73 . The first tubes  74  may include a plurality of spaced apart fins (not shown) extending radially outwardly therefrom and/or a plurality of space apart fins (not shown) extending radially inwardly therein to enhance a transfer of thermal energy between the fluid from the source of cooled fluid  30  and the fluid from the heat exchanger  26 . The first tubes  74  and the fins are produced from a thermally conductive material such as copper, for example. The second inlet  66  and the second outlet  70  are fluidly connected by the open areas  78  defined by the first tubes  74 . The open areas  78  receive the fluid from the heat exchanger  26  therethrough. The flow of the fluid through the open areas  78  is substantially parallel to the flow of the fluid from the heat exchanger  26  through the second inlet  66  and the second outlet  70  and substantially perpendicular to the flow of fluid from the source of cooled fluid  30  through the first tubes  74 . 
     As illustrated in  FIG. 1 , the thermal energy exchanger  38  further includes a third manifold  80 , a fourth manifold  82 , and a plurality of second tubes  84  extending between the manifolds  80 ,  82  and through the manifolds  72 ,  73 . Each of the manifolds  80 ,  82  and the second tubes  84  includes a phase change material  86  disposed therein. The phase change material  86  can be any material that melts and solidifies at predetermined temperatures such as a paraffin wax, an alcohol, water, and any combination thereof, for example, and is capable of storing and releasing thermal energy. In the embodiment shown, the phase change material  86  is adapted to absorb thermal energy of the fluid flowing through the open areas  78  when the fuel-powered engine is not in operation, and release thermal energy to the fluid from the source of cooled fluid  30  flowing through the first tubes  74  when the fuel-powered engine is in operation. 
     As shown, the manifolds  80 ,  82  are formed on opposite sides of the housing  60  adjacent an outer surface of the manifolds  72 ,  73 , respectively, to enhance a transfer of thermal energy among the fluid from the source of cooled fluid  30 , the fluid from the heat exchanger  26 , and the phase change material  86 . At least one of the manifolds  80 ,  82  can include an opening (not shown) formed therein to facilitate a filling of the manifolds  80 ,  82  and the second tubes  84 . In certain embodiments, the phase change material  86  is heated above a melting point thereof to liquefy the phase change material  86 . The liquid phase change material  86  is then poured into the opening, filling the manifolds  80 ,  82  and the second tubes  84 . A cover (not shown) can be disposed over the opening to militate against a leakage of the phase change material  86  therefrom. 
     The second tubes  84  are substantially parallel in relation to each other and disposed in the open areas  78  defined by the first tubes  74 . As shown, the second tubes  84  are interleaved with the first tubes  74  to further enhance the transfer of thermal energy between the fluids and the phase change material  86 , if desired. It is understood that the second tubes  84  may include a plurality of spaced apart fins (not shown) extending radially outwardly therefrom and/or a plurality of space apart fins (not shown) extending radially inwardly therein to enhance a transfer of thermal energy among the fluid from the source of cooled fluid  30 , the fluid from the heat exchanger  26 , and the phase change material  86 . 
     In use, when the fuel-powered engine of the vehicle is in operation, the fluid from the source of cooled fluid  30  circulates through the conduits  36 ,  46 . Accordingly, the fluid from the source of cooled fluid  30  circulates through the evaporator core  24  and the thermal energy exchanger  38 . 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  29  to flow through the heat exchanger  26  and the heater core  28 , and into the outlet and distribution section. The fluid circulating through the conduit  46  flows into and through the first tubes  74  of the thermal energy exchanger  38 . The fluid circulating through the conduit  46  absorbs thermal energy from the phase change material  86  disposed in the manifolds  80 ,  82  and the second tubes  84 . The transfer of thermal energy cools and solidifies the phase change material  86 . Additionally, the phase change material  86  cools the fluid circulating through conduit  40  and the heat exchanger  26  by absorbing thermal energy therefrom. The thermal energy absorbed by the phase change material  86  is then transferred to the fluid from the source of cooled fluid  30 . 
     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 ,  46 . Accordingly, the fluid does not circulate through the evaporator core  24  or the thermal energy exchanger  38 . The pump  42  causes the fluid disposed in the heat exchanger  26  to circulate through the conduit  40  and the thermal energy exchanger  38 . The fluid flows into and through the open areas  78  of the thermal energy exchanger  38 , releasing thermal energy to the phase change material  86  disposed in the manifolds  80 ,  82  and the second tubes  84  thereof. Accordingly, the fluid is cooled by the phase change material  86 . The air from the inlet section  16  flows into and through the evaporator core  24  where a temperature thereof is unchanged. The air then exits the evaporator core  24  and is selectively permitted to flow through the heat exchanger  26  and the heater core  28 . 
     In the heat exchanger  26 , the air is cooled to a desired temperature by a transfer of thermal energy from the air to the fluid circulating therethrough. The fluid absorbs and transfers the thermal energy from the air to the phase change material  86  disposed in the manifolds  80 ,  82  and the second tubes  84  of the thermal energy exchanger  38 . Thus, the phase change material  86  is caused to melt. The conditioned cooled air then exits the heat exchanger  26  and flows through the heater core  28  and into the outlet and distribution section. 
       FIG. 2  shows a thermal energy exchanger  138  for use in the HVAC system  10  according to another embodiment of the invention. The thermal energy exchanger  138  has a cross-counter flow configuration and includes a main housing  160  having a hollow interior. The main housing  160  may be made of conventional materials such as polypropylene, for example. In the embodiment shown, the main housing  160  is generally rectangular in shape. It is understood that the main housing  160  can have other shapes as desired such as cylindrical, for example. The main housing  160  includes a first inlet  164 , a second inlet  166 , a first outlet  168 , and a second outlet  170  formed thereon. The inlets  164 ,  166  and the outlets  168 ,  170  are formed to extend laterally outwardly from the main housing  160 . The first inlet  164  and the first outlet  168  are in fluid communication with the source of cooled fluid  30 , shown in  FIG. 1 . The second inlet  166  and the second outlet  170  are in fluid communication with the heat exchanger  26 , shown in  FIG. 1 . An insulating material (not shown) can be disposed on an outer surface of the main housing  160  to militate against a dissipation of thermal energy therefrom. 
     The first inlet  164  and the first outlet  168  are fluidly connected by an inlet first manifold  172 , an outlet second manifold  173 , and a plurality of first tubes  174  extending therebetween. The manifolds  172 ,  173  and the first tubes  174  are disposed in the hollow interior of the thermal energy exchanger  138  and receive the fluid from the source of cooled fluid  30  therethrough. The manifolds  172 ,  173  are formed on opposite sides of the main housing  160  substantially parallel to a flow of the fluid from the source of the cooled fluid  30  into the first inlet  164  and from the first outlet  168 . As shown, each of the manifolds  172 ,  173  perform as a diffuser so as to gradually decrease a rate of flow of the fluid from the source of cooled fluid  30  into the thermal energy exchanger  138  and gradually increase a rate of flow of the fluid from the source of cooled fluid  30  from the thermal energy exchanger  138 . It is understood, however, that the manifolds  172 ,  173  can have any shape as desired. 
     The first tubes  174  are substantially parallel in relation to each other and are spaced apart to define a series of open areas  178  therebetween. The flow of the fluid through the first tubes  174  is substantially parallel to the flow of the fluid from the source of the cooled fluid  30  through the first inlet  164 , the first outlet  168 , and the manifolds  172 ,  173 . The first tubes  174  may include a plurality of spaced apart fins (not shown) extending radially outwardly therefrom and/or a plurality of space apart fins (not shown) extending radially inwardly therein to enhance a transfer of thermal energy between the fluid from the source of cooled fluid  30  and the fluid from the heat exchanger  26 . The first tubes  174  and the fins are produced from a thermally conductive material such as copper, for example. The second inlet  166  and the second outlet  170  are fluidly connected by the open areas  178  defined by the main housing  160  and the first tubes  174 . The open areas  178  receive the fluid from the heat exchanger  26  therethrough. The flow of the fluid through the open areas  178  is substantially parallel to the flow of the fluid from the heat exchanger  26  through the second inlet  166  and the second outlet  170  and substantially perpendicular to the flow of fluid from the source of cooled fluid through the first tubes  174 . 
     The thermal energy exchanger  138  further includes a third manifold  180 , a fourth manifold  182 , and a plurality of second tubes  184  extending between the manifolds  180 ,  182 . Each of the manifolds  180 ,  182  and the second tubes  184  includes a phase change material  186  disposed therein. The phase change material  186  can be any material that melts and solidifies at predetermined temperatures such as a paraffin wax, an alcohol, water, and any combination thereof, for example, and is capable of storing and releasing thermal energy. In the embodiment shown, the phase change material  186  is adapted to absorb thermal energy of the fluid flowing through the open areas  178  when the fuel-powered engine is not in operation, and release thermal energy to the fluid from the source of cooled fluid  30  flowing through the first tubes  174  when the fuel-powered engine is in operation. 
     The manifold  180  shown includes an opening  187  formed therein to facilitate a filling of the manifolds  180 ,  182  and the second tubes  184 . It is understood that the opening  187  can be formed in the manifold  182  if desired. In certain embodiments, the phase change material  186  is heated above a melting point thereof to liquefy the phase change material  186 . The liquid phase change material  186  is then poured into the opening  187 , filling the manifolds  180 ,  182  and the second tubes  184 . A cover  188  is disposed over the opening  187  to militate against a leakage of the phase change material  186  therefrom. 
     As shown, the manifolds  180 ,  182  are formed on opposite sides of the main housing  160  adjacent an inner surface of the manifolds  172 ,  173 , respectively, to enhance a transfer of thermal energy among the fluid from the source of cooled fluid  30 , the fluid from the heat exchanger  26 , and the phase change material  186 . The second tubes  184  are substantially parallel in relation to each other and disposed in the open areas  178  defined by the first tubes  174 . As shown, the second tubes  184  are interleaved with the first tubes  174  to further enhance the transfer of thermal energy between the fluids and the phase change material  186 , if desired. It is understood that the second tubes  184  may include a plurality of spaced apart fins (not shown) extending radially outwardly therefrom and/or a plurality of space apart fins (not shown) extending radially inwardly therein to enhance a transfer of thermal energy among the fluid from the source of cooled fluid  30 , the fluid from the heat exchanger  26 , and the phase change material  186 . 
     In use, when the fuel-powered engine of the vehicle is in operation, the fluid from the source of cooled fluid  30  circulates through the evaporator core  24  and the thermal energy exchanger  138 . 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  29  to flow through the heat exchanger  26  and the heater core  28 , and into the outlet and distribution section. The fluid circulating through the conduit  46  flows into and through the first tubes  174  of the thermal energy exchanger  138 . The fluid circulating through the first tubes  174  absorbs thermal energy from the phase change material  186  disposed in the manifolds  180 ,  182  and the second tubes  184 . The transfer of thermal energy cools and solidifies the phase change material  186 . Additionally, the phase change material  186  cools the fluid circulating through the heat exchanger  26  by absorbing thermal energy therefrom. The thermal energy absorbed by the phase change material  186  is then transferred to the fluid from the source of cooled fluid  30 . 
     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 evaporator core  24  or the thermal energy exchanger  138 . The pump  42 , shown in  FIG. 1 , causes the fluid disposed in the heat exchanger  26  to circulate through the thermal energy exchanger  138 . The fluid flows into and through the open areas  178  of the thermal energy exchanger  138 , releasing thermal energy to the phase change material  186  disposed in the manifolds  180 ,  182  and the second tubes  184  thereof. Accordingly, the fluid is cooled by the phase change material  186 . The air from the inlet section  16  flows into and through the evaporator core  24  where a temperature thereof is unchanged. The air then exits the evaporator core  24  and is selectively permitted to flow through the heat exchanger  26  and the heater core  28 . 
     In the heat exchanger  26 , the air is cooled to a desired temperature by a transfer of thermal energy from the air to the fluid circulating therethrough. The fluid absorbs and transfers the thermal energy from the air to the phase change material  186  disposed in the manifolds  180 ,  182  and the second tubes  184  of the thermal energy exchanger  138 . Thus, the phase change material  186  is caused to melt. The conditioned cooled air then exits the heat exchanger  26  and flows through the heater core  28  and into the outlet and distribution section. 
       FIG. 3  shows a thermal energy exchanger  238  for use in the HVAC system  10  according to another embodiment of the invention. The thermal energy exchanger  238  has a cross-counter flow configuration and includes a main housing  260  having a hollow interior. The main housing  260  may be made of conventional materials such as polypropylene, for example. In the embodiment shown, the main housing  260  is generally rectangular in shape. It is understood that the main housing  260  can have other shapes as desired such as cylindrical, for example. The main housing  260  includes a first inlet  264 , a second inlet  266 , a first outlet  268 , and a second outlet  270  formed thereon. The inlets  264 ,  266  and the outlets  268 ,  270  are formed to extend laterally outwardly from the main housing  260 . The first inlet  264  and the first outlet  268  are in fluid communication with the source of cooled fluid  30 , shown in  FIG. 1 . The second inlet  266  and the second outlet  270  are in fluid communication with the heat exchanger  26 , shown in  FIG. 1 . An insulating material (not shown) can be disposed on an outer surface of the main housing  260  to militate against a dissipation of thermal energy therefrom. 
     The first inlet  264  and the first outlet  268  are fluidly connected by an inlet first manifold  272 , an outlet second manifold  273 , and a plurality of first tubes  274  extending therebetween. The manifolds  272 ,  273  and the first tubes  274  are disposed in the hollow interior of the thermal energy exchanger  238  and receive the fluid from the source of cooled fluid  30  therethrough. The manifolds  272 ,  273  are formed on opposite sides of the housing  260  substantially parallel to a flow of the fluid from the source of the cooled fluid  30  into the first inlet  264  and from the first outlet  268 . As shown, each of the manifolds  272 ,  273  perform as a diffuser so as to gradually decrease a rate of flow of the fluid from the source of cooled fluid  30  into the thermal energy exchanger  238  and gradually increase a rate of flow of the fluid from the source of cooled fluid  30  from the thermal energy exchanger  238 . It is understood, however, that the manifolds  272 ,  273  can have any shape as desired. 
     The first tubes  274  are substantially parallel in relation to each other and are spaced apart to define a series of open areas  278  therebetween. The flow of the fluid through the first tubes  274  is substantially parallel to the flow of the fluid from the source of the cooled fluid  30  through the first inlet  264 , the first outlet  268 , and the manifolds  272 ,  273 . The first tubes  274  may include a plurality of spaced apart fins (not shown) extending radially outwardly therefrom and/or a plurality of space apart fins (not shown) extending radially inwardly therein to enhance a transfer of thermal energy between the fluid from the source of cooled fluid  30  and the fluid from the heat exchanger  26 . The first tubes  274  and the fins are produced from a thermally conductive material such as copper, for example. The second inlet  266  and the second outlet  270  are fluidly connected by the open areas  278  defined by the main housing  260  and the first tubes  274 . The open areas  278  receive the fluid from the heat exchanger  26  therethrough. The flow of the fluid through the open areas  278  is substantially parallel to the flow of the fluid from the heat exchanger  26  through the second inlet  266  and the second outlet  270  and substantially perpendicular to the flow of fluid from the source of cooled fluid through the first tubes  274 . 
     The thermal energy exchanger  238  further includes a third manifold  280 , a fourth manifold  282 , and a plurality of second tubes  284  extending between the manifolds  280 ,  282 . Each of the second tubes  284  surrounds alternating first tubes  274 , forming a substantially cylindrical space  285  therebetween. Each of the manifolds  280 ,  282  and the space  285  between the tubes  274 ,  284  includes a phase change material  286  disposed therein. The phase change material  286  can be any material that melts and solidifies at predetermined temperatures such as a paraffin wax, an alcohol, water, and any combination thereof, for example, and is capable of storing and releasing thermal energy. In the embodiment shown, the phase change material  286  is adapted to absorb thermal energy of the fluid flowing through the open areas  278  when the fuel-powered engine is not in operation, and release thermal energy to the fluid from the source of cooled fluid  30  flowing through the first tubes  274  when the fuel-powered engine is in operation. 
     The manifold  282  shown includes an opening  287  formed therein to facilitate a filling of the manifolds  280 ,  282  and the space  285  between the tubes  274 ,  284 . It is understood that the opening  287  can be formed in the manifold  280  if desired. In certain embodiments, the phase change material  286  is heated above a melting point thereof to liquefy the phase change material  286 . The liquid phase change material  286  is then poured into the opening  287 , filling the manifolds  280 ,  282  and the space  285  between the tubes  274 ,  284 . A cover  288  is disposed over the opening  287  to militate against a leakage of the phase change material  286  therefrom. 
     As shown, the manifolds  280 ,  282  are formed on opposite sides of the main housing  260  adjacent an inner surface of the manifolds  272 ,  273 , respectively, to enhance a transfer of thermal energy among the fluid from the source of cooled fluid  30 , the fluid from the heat exchanger  26 , and the phase change material  286 . The second tubes  284  are substantially parallel in relation to each other and disposed in the open areas  278  defined by the first tubes  274 . As shown, the first tubes  274  surrounded by the second tubes  284  are interleaved with the remaining first tubes  274  to further enhance the transfer of thermal energy between the fluids and the phase change material  286 , if desired. It is understood that the second tubes  284  may include a plurality of spaced apart fins (not shown) extending radially outwardly therefrom and/or a plurality of space apart fins (not shown) extending radially inwardly therein to enhance a transfer of thermal energy among the fluid from the source of cooled fluid  30 , the fluid from the heat exchanger  26 , and the phase change material  286 . 
     In use, when the fuel-powered engine of the vehicle is in operation, the fluid from the source of cooled fluid  30  circulates through the evaporator core  24  and the thermal energy exchanger  238 . 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  29  to flow through the heat exchanger  26  and the heater core  28 , and into the outlet and distribution section. The fluid circulating through the conduit  46  flows into and through the first tubes  274  of the thermal energy exchanger  238 . The fluid circulating through the first tubes  274  absorbs thermal energy from the phase change material  286  disposed in the manifolds  280 ,  282  and the space  285  formed between the tubes  274 ,  284 . The transfer of thermal energy cools and solidifies the phase change material  286 . Additionally, the phase change material  286  cools the fluid circulating through the heat exchanger  26  by absorbing thermal energy therefrom. The thermal energy absorbed by the phase change material  286  is then transferred to the fluid from the source of cooled fluid  30 . 
     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 evaporator core  24  or the thermal energy exchanger  238 . The pump  42 , shown in  FIG. 1 , causes the fluid disposed in the heat exchanger  26  to circulate through the thermal energy exchanger  238 . The fluid flows into and through the open areas  278  of the thermal energy exchanger  238 , releasing thermal energy to the phase change material  286  disposed in the manifolds  280 ,  282  and the space  285  formed between the tubes  274 ,  284  thereof. Accordingly, the fluid is cooled by the phase change material  286 . The air from the inlet section  16  flows into and through the evaporator core  24  where a temperature thereof is unchanged. The air then exits the evaporator core  24  and is selectively permitted to flow through the heat exchanger  26  and the heater core  28 . 
     In the heat exchanger  26 , the air is cooled to a desired temperature by a transfer of thermal energy from the air to the fluid circulating therethrough. The fluid absorbs and transfers the thermal energy from the air to the phase change material  286  disposed in the manifolds  280 ,  282  and the space  285  formed between the tubes  274 ,  284  of the thermal energy exchanger  238 . Thus, the phase change material  286  is caused to melt. The conditioned cooled air then exits the heat 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.