Abstract:
An air-handling system selectively heats and/or cools a target space by circulating ambient air from the target space across a heat exchanger. The system operates along an air flow path having an inlet from the target space and an outlet back into the target space. Air-handling turbines or pumps are located near the inlet and outlet. The heat exchanger is placed in the flow path between the turbines or pumps. The heat exchanger transfers heat into or out of the air, causing a natural pressure increase or decrease in the air. The turbines or pumps are configured to harvest work from the induced pressure differential in order to conserve energy. A combustion chamber may be included directly in the flow path upstream of the heat exchanger for combusting a fuel in the air during a high heating mode.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Continuation of U.S. Ser. No. 12/917,064 filed Nov. 1, 2010, now US 2011/0100011 published May 5, 2011, which claims priority to Provisional Patent Application No. 61/256,559 filed Oct. 30, 2009, the entire disclosures of which are hereby incorporated by reference and relied upon. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    A thermodynamic system for selectively heating and/or cooling a target space, and more particularly such a thermodynamic system in which ambient air comprises the working fluid therefor. 
         [0004]    2. Description of Related Art 
         [0005]    Thermodynamic systems in the form of heat pumps are used in the prior art to alternatively heat or cool a target space in standard heating/cooling modes. Heat pumps generally include a compressor, two heat exchangers, and an expander all disposed in a common fluid flow path. Most heat pump systems are of the closed loop type in which the working fluid, typically a two-phase refrigerant, is circulated through the system so as to absorb heat through one of the heat exchangers and to reject heat from the other heat exchanger. When the target space is to be heated, the system is configured so that the heat exchanger that rejects heat will be stationed in the target space or in thermodynamic communication therewith such as via suitable plumping or ducting. Alternatively, when the target space is to be cooled, the system is configured so that the heat exchanger that rejects heat will be stationed in (or ducted to) the ambient environment or other suitable heat sink. Both configurations are considered within a standard heating/cooling mode. Not all heat pump systems are of the closed loop type; some heat pump systems have been proposed in an open-loop arrangement using ambient air as the working fluid. 
         [0006]    A target space may be any enclosed or localized space. The target space may be a human environment, such as a building or the passenger compartment in an automobile. Alternatively, the target space may be a relatively small or large area for objects like a personal computer enclosure or a server room. 
         [0007]    While such known heat pump systems are adequate in many climates, they are frequently unable to provide adequate heating during extremely cold conditions. This is because a typically sized system is not capable of cooling the working fluid (even in the case of a hazardous refrigerant) to a cold enough temperature so that it has capacity to absorb heat from an exceptionally cold ambient atmosphere. In these conditions, it may be necessary to supplement the heat pump with a secondary furnace, stove, or other heating apparatus to adequately heat the target space. 
         [0008]    U.S. Pat. No. 3,686,893, issued to Thomas C. Edwards on Aug. 29, 1972 and U.S. Pat. No. 4,008,426, issued to Thomas C. Edwards on May 9, 1978 (hereinafter referred to as “the Edwards patents”), show a positive displacement rotating vane-type device that operates a thermodynamic cycle for simultaneously compressing and expanding a working fluid which may be air. The devices shown in the Edwards patents each have a stator housing and a rotor disposed in the stator housing defining an interstitial space therebetween. A plurality of vanes are operatively disposed between the rotor and the stator housing for dividing the interstitial space into revolving compression and expansion chambers. The vanes are spring loaded to slidably engage the inner wall of the stator housing. The rotor is rotatably disposed within the stator housing for rotating in a first direction. While the rotor is rotating, the vanes slide along the inner wall of the stator housing and simultaneously compress the working fluid in the compression chambers and expand the fluid in the expansion chambers. 
         [0009]    The stator housing of the Edwards patents further define several ports for conducting the working fluid into and out of the device. These ports include a compression chamber inlet, a compression chamber outlet, an expansion chamber inlet, and an expansion chamber outlet. Additionally, the stator housing of the Edwards patents defines an expansion chamber inlet and an expansion chamber outlet. The compression chamber inlet and the expansion chamber outlet are both disposed on the side of the stator housing and communicate with different chambers. Thus, the working fluid enters and exits the device of the Edwards patents through various ports in a carefully arranged radial direction. 
         [0010]    The Edwards patents are typical of prior art positive displacement rotating vane-type devices where the transfer of working fluid into and out of the device via ports is accomplished though localized piping that is arranged to prevent inadvertent mixing of high and low pressure fluids. Elaborate seals and other measures are sometimes taken to ensure the high and low pressure fluids never mix, and thereby reduce operating efficiencies. Such measures add considerably to the complexity and cost of positive displacement rotating vane-type devices. 
         [0011]    There exists a need for further efficiency improvements in the field of heat pump systems, and more particularly for air-aspirated systems in which ambient air serves as the working fluid. There exists a need for a heat pump system that can fully meet the heating needs of a target space during very cold conditions. Furthermore, there exists a need for a heat pump system that is capable of efficiently transferring a working fluid (be it air or otherwise) between high and low pressure ports of a positive displacement rotating vane-type device without unnecessary complexity or cost. 
       BRIEF SUMMARY OF THE INVENTION 
       [0012]    The invention comprises a high-efficiency air moving system for circulating ambient air in a target space across a heat exchanger. A confined flow path is established for routing ambient air as a working fluid from an inlet to an outlet. In this configuration, the inlet is disposed to receive ambient air from the target space as the working fluid and the outlet is disposed for expelling the air out of the flow path and back into the ambient air in the target space. A first turbine or pump is disposed in the flow path adjacent the inlet. The first turbine or pump is configured to control substantially all of the movement of air entering the flow path through the inlet. A second turbine or pump is disposed in the flow path adjacent the outlet. The second turbine or pump is configured to control substantially all of the movement of air exiting the flow path through the outlet. A heat exchanger is located in the flow path between the first and second turbines or pumps. The heat exchanger is configured to move heat into or out of the air in the flow path and thereby heat or cool the air in the target space when the air is subsequently discharged from the outlet. The addition or subtraction of heat in the flow path via the heat exchanger causes a corresponding pressure increase or pressure decrease, respectively, in the air between the first and second turbines or pumps relative to the ambient air. The improvement of this invention comprises at least one of the first turbine or pump and the second turbine or pump being configured to harvest work from the differentiated pressure of the air between the first and second turbines. 
         [0013]    The system of the present invention enables a more efficient air moving system than air moving systems of the prior art because it utilizes at least two turbines or pumps on opposite sides (i.e., upstream and downstream) of a heat exchanger that are configured to reclaim available pressure energy from the working fluid caused by the addition or subtraction of heat. As a result, the system is more readily adapted to heat or cool a target space while concurrently conserving energy by harvesting at least some of the residual energy in the working fluid that exists in the form of a pressure differential above the ambient atmospheric conditions. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0014]    These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description and appended drawings, wherein: 
           [0015]      FIG. 1  is a view showing an air aspirated hybrid heat pump and heat engine system according to an embodiment of this invention; 
           [0016]      FIG. 2  is a simplified, partially exploded view of a positive displacement rotating vane-type device as in  FIG. 1  but configured in a closed-loop arrangement; 
           [0017]      FIG. 3  shows an alternative embodiment of the invention wherein the positive displacement rotating vane-type device of  FIG. 1  is configured in a cooling mode; 
           [0018]      FIG. 4  is a view as in  FIG. 3  but where the device is configured in a heating mode; and 
           [0019]      FIG. 5  is yet another alternative embodiment of the air aspirated hybrid heat pump and heat engine system utilizing independent compressor and expander devices to achieve either a fixed or variable asymmetric compression/expansion ratio. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, one embodiment of the invention is shown in  FIG. 1  as an open loop air aspirated hybrid heat pump and heat engine system  20  for selectively heating and cooling a target space  22 . The target space  22  can be an interior room in a building, the passenger compartment of an automobile, a computer enclosure, or any other localized space to be heated and/or cooled. The working fluid of the system  20  in this embodiment is most preferably air, however in general the principles of this invention will permit other substances to be used for the working fluid including multi-phase refrigerants in suitable closed-loop configurations. 
         [0021]    The hybrid heat pump and heat engine system  20  includes a working fluid (e.g., air) flow path  24 , generally indicated in  FIG. 1 , extending from an inlet  26  to an outlet  28 . The inlet  26  receives working fluid (air in this example) from an ambient source  30 , while the outlet  28  discharges air from the system  20  back to the ambient environment  30 . Preferably, the inlet  26  and outlet  28  are both disposed outside of the target space  22  and in the atmosphere  30  when atmospheric air is used as the working fluid. 
         [0022]    A heat exchanger  32  is disposed in the flow path  24  between the inlet  26  and the outlet  28 . In the exemplary embodiment of  FIG. 1 , the heat exchanger  32  is disposed in the target space  22  for transferring heat between the target space  22  and the working fluid in the flow path  24 . In a standard heating/cooling mode of operation, the system  20  is configured to either transfer heat from the working fluid to the target space  22  to heat the target space  22  or alternatively to transfer heat from the target space  22  to the working fluid to cool the target space  22 . The heat exchanger  32  is preferably a high efficiency heat exchanger  32  having a large surface area, such as by plurality of fins, for convectively transferring heat between air in the target space  22  and the working fluid in the flow path  24 . Preferably, a fan  34  or a blower is disposed adjacent to the heat exchanger  32  for propelling the air in the target space  22  through the heat exchanger  32  to assist in the heat exchange between the air in the target space  22  and the air in the heat exchanger  32 . Of course, conductive methods of heat transfer can also be used instead of or in addition to convective methods suggested by the fan  34  in the target space  22  in  FIG. 1 . 
         [0023]    In the exemplary embodiment of  FIG. 1 , a positive displacement rotating vane-type device  36  is disposed in the flow path  24  for simultaneously compressing and expanding the air. While a positive displacement type device  36  is preferred for all implementations of this invention, some alternative embodiments of the invention as applied to the hybrid heat pump principles described below may substitute a blower that is not of the positive displacement variety in place of the positive displacement rotating vane-type device  36 . Such substitution is enabled by the heat pump principles of this invention which deal with what can be considered a very low pressure ratio Brayton Cycle. As such, those of skill in the art will appreciate that a common fan or blower could be effective at maintaining a suitable pressure differential, namely on the order of Atmospheric plus or minus 20-30%. Of course, efficiently losses would be expected to be greater with common fan or blower devices, but such may be acceptable in certain applications. 
         [0024]    The vane-type device  36  includes a generally cylindrical stator housing  38  longitudinally between spaced and opposite ends  40 . A rotor  42  is disposed within the stator housing  38  and establishes an interstitial space  22  between the rotor  42  and the inner wall  44  of the stator housing  38 . A plurality of vanes  46  are operatively disposed between the rotor  42  and the stator housing  38  for dividing the interstitial space  22  into intermittent compression and expansion chambers  48 ,  50 . The vanes  46  are spring loaded to slidably engage the inner wall  44  of the stator housing  38 . Accordingly, the plurality of compression  48  and expansion  50  chambers are each defined by a space between two adjacent vanes  46 . As the rotor  42  rotates relative to the stator housing  38 , the chambers  48 ,  50  defined between adjacent vanes  46  sequentially and progressively transition between compression and expansion stages in a continuum so that the working fluid is simultaneously compressed in compression chambers and expanded in expansion chambers. That is to say, at any time during rotation of the rotor  42 , working fluid is being compressed in one portion of the device  36  and expanded in another portion of the device  36 . 
         [0025]    Two arcuately spaced transition points correspond with maximum compression and maximum expansion of the working fluid. In the particular embodiment illustrated in  FIG. 1 , these transition points occur at the 12 o&#39;clock and 6 o&#39;clock positions of the stator housing  38 , with the 12 o&#39;clock position being the point of maximum expansion and the 6 o&#39;clock position being the point of maximum compression. In alternative configurations of the rotary device  36 , there may be only one transition point corresponding to either maximum compression or maximum expansion, such as in systems like that shown in  FIG. 5  were the compression and expansion functions are carried out in separate devices. Or, there may be three or more transition points where a rotary device incorporates multiple lobes as shown for example in U.S. Pat. No. 7,556,015 to Staffend, issued Jul. 7, 2009, the entire disclosure of which is hereby incorporated by reference. In any case, therefore, the transition points may be defined as the rotary positions where the chambers  48 ,  50  between adjacent vanes  46  transition between the compression and expansion stages, respectively. 
         [0026]    Working fluid ports are provided to move the working fluid into and out of the device  36 . In the embodiment illustrated in  FIG. 1 , the ports include a compression chamber inlet  52 , a compression chamber outlet  54 , an expansion chamber inlet  56 , and an expansion chamber outlet  58 . The compression chamber inlet  52  and expansion chamber outlet  58  are located adjacent to the 12 o&#39;clock position transition point corresponding to maximum expansion. By contrast, the expansion chamber inlet  56  and compression chamber outlet  54  are located adjacent to the 6 o&#39;clock position transition point corresponding to maximum expansion. The compression chamber inlet  52  is in fluid communication with the inlet  26  for receiving the atmospheric air, and the expansion chamber outlet  58  is in fluid communication with the outlet  28  for discharging the air out of the flow path  24  to the atmosphere  30 . The heat exchanger  32  is in fluid communication with the vane-type device  36  through the compression chamber outlet  54  and the expansion chamber inlet  56 . 
         [0027]    The compression chamber inlet  52  and the expansion chamber outlet  58  are generally longitudinally aligned with one another relative to the stator housing  38  for simultaneously communicating with the same chamber  48 ,  50 . In other words, the compression chamber inlet  52  and the expansion chamber outlet  58  may be located on opposite longitudinal ends of the stator housing  38  so as to communicate simultaneously with a common chamber or chambers  48 ,  50 . Thus a compression chamber port (inlet  52  in this example) and an expansion chamber port (outlet  58  in this example) are continuously in communication with at least one common chamber at or near a transition point. A pump  60  may be disposed in the flow path  24  between inlet  26  and the compression chamber inlet  52  for propelling the working fluid into the stator housing  38  through the compression chamber inlet  52 . The arrangement of the ports according to this invention enable a greater fractional use of the swept volume of the rotating vane-type device. Furthermore, the flow of working fluid through the device  36  is improved. 
         [0028]    The rotor  42  is rotatably disposed within the stator housing  38  for rotating in a first direction. While the rotor  42  is rotating, the vanes  46  slide along the inner wall  44  of the stator housing  38  and simultaneously reduce the volume of the compression chambers  48  and increase the volume of the expansion chambers  50 . In the exemplary embodiment, vane-type device  36  accomplishes the simultaneous compression and expansion because the cross-section of the inner wall  44  of the stator housing  38  is circular and the rotor  42  rotates about an axis A that is off-set from the center of the circular inner wall  44 . Alternatively, the stator housing  38  could be elliptically shaped and the rotor  42  could rotate about the center of the elliptical stator housing  38 . Other configurations are of course possible, including those described in U.S. Pat. No. 7,556,015 as well as those described in priority document U.S. Provisional Application Ser. No. 61/256,559 filed Oct. 30, 2009, the entire disclosure of which is hereby incorporated by reference and relied upon. 
         [0029]    The embodiment of  FIG. 1  can operate in a standard heating/cooling mode or in an optional high heating mode. In the standard heating/cooling mode, the pump  60  propels atmospheric air into the vane-type device  36  through the compression chamber inlet  52 . The temperature and pressure of the air both increase as the air is compressed in the compression chambers  48  before exiting the device  36  through the compression chamber outlet  54 . The pressurized and warmed air flows passively through a dormant combustion chamber  62  and then to the heat exchanger  32  where it dispenses heat to warm the target space  22 . Exiting the heat exchanger  32 , the cooled but still pressurized air then flows back to the device  36  and enters the stator housing  38  via the expansion chamber inlet  56  at or near the 6 o&#39;clock transition point. The air is directed into the next available expansion chamber  50  where is carried and swept in an expanding volume to depressurize, preferably back to the atmospheric pressure. Available pressure energy in the working fluid is thus released from the working fluid to act on the rotor  42  as a torque and thereby directly offset the energy required on the compression side of the rotor  42  working to simultaneously compress the working fluid in chambers  48 . 
         [0030]    Next, the air is pushed out of the vane-type device  36  through the expansion chamber outlet  58  by the air entering the vane-type device  36  through the compression chamber inlet  52 . Finally, the air is discharged to the atmosphere  30  through the outlet  28 . The difference in the pressure of the air entering the expansion chambers  50  and the atmospheric pressure represents potential energy. The expansion chambers  50  of the vane-type device  36  harness that potential energy and use it to provide power to the rotor  42 . 
         [0031]    The system includes a combustion chamber  62  in the flow path  24  between the compression chamber outlet  54  of the vane-type device  36  and the heat exchanger  32 . During the standard heating/cooling mode, described above, the combustion chamber  62  remains dormant. However, during an optional high heating mode, a fuel introduced into the combustion chamber  62  is combusted, or burned, in the working fluid to greatly increase both its temperature and pressure within the flow path  24 . The fuel may be any suitable type including for examples natural gas, propane, gasoline, methanol, grains, particulates or other combustible materials. 
         [0032]    The compression chambers  48  of the vane-type device  36  compress the air by a first predetermined ratio, and the expansion chambers  50  of the vane-type device  36  expand the air by a second predetermined ratio. In the  FIG. 1  embodiment, the first and second predetermined ratios are approximately equal to one another. When accounting for heat transfers and losses, the equal expansion/compression ratios are adequate to extract all available work energy from the fluid during the standard heating/cooling modes of operation. However, following the combustion of air in the combustion chamber  62  during the high heating mode, the pressure of the air in the flow path  24  is substantially elevated such that the vane-type device  36  cannot be expected to fully (or nearly fully) depressurize all of the air in the flow path  24  back to the atmospheric pressure. Therefore, a secondary expander  66  may be provided to receive surplus working fluid. The secondary expander  66  may be located downstream of a valve  64  disposed in a spur flow path adjoining the main flow path  24  extending between the heat exchanger  32  and the expansion chamber inlet  56 . During the standard heating/cooling mode, the valve  64  may be closed to direct all of the working fluid in the flow path  24  from the heat exchanger  32  to the expansion chamber inlet  56 . Although not shown, a pressure regulator may be included in the flow path  24  leading to the expansion chamber inlet  56 , and the valve  64  may operate in conjunction with the pressure regulator to open when the pressure regulator reaches a maximum pressure threshold. During the high heating mode when excesses of pressure are generated in the working fluid, the valve  64  is manipulated (either automatically or manually) to direct a portion of the working fluid from the heat exchanger  32  to a secondary expander  66 . The remaining portion of the working fluid travels to the expansion chamber inlet  56  as described above. Thus, in order to improve the energy efficiency of the system, it is advantageous to redirect at least some of the pressurized air from the heat exchanger  32  to the secondary expander  66 , which is mechanically connected to an energy receiving device, here an electric generator  68 , and there reclaimed. Preferably, all of the surplus working fluid, i.e., that portion of the working fluid that cannot be fully expanded to ambient pressure in the expansion chambers  50 , is directed to the secondary expander  66  where potential energy in the working fluid is converted into another useful form of energy. The vane-type device  36  and the electric generator  68  work together to capture and convert any residual pressure energy remaining in the working fluid before it is discharged to ambient  30 . 
         [0033]    In operation, during the high heating mode, the pump  60  propels atmospheric air into the vane-type device  36  through the compression chamber inlet  52 . The temperature and pressure of the air both increase as the air is compressed in the compression chambers  48 . The pressurized and warmed air then exits the vane-type device  36  through the compression chamber outlet  54  and flows into the combustion chamber  62 . In the combustion chamber  62 , the fuel is mixed with the air and combusted to greatly increase the pressure and temperature of the air. The air then flows through the heat exchanger  32  where it dispenses heat to warm the target space  22 . Next, the valve  64  directs a predetermined amount of the air to the expansion chamber inlet  56  of the vane-type device  36  and the remaining air to the secondary expander  66 . In the vane-type device  36 , the pressurized air is expanded, preferably to or nearly to the atmospheric pressure, before it is discharged out of the flow path  24  and to the atmosphere  30  through the outlet  28 . A secondary heat exchanger (not shown) may be incorporated into the flow path  24  between the expansion chamber outlet  58  and the flow path outlet  28  to scavenge any remaining heat in the working fluid and thereby further increase thermodynamic efficiencies. Ideally, the temperature of the working fluid as it emerges from the outlet  28  is at or only very slightly greater than the ambient air temperature. The air in the secondary expander  66  is also expanded, preferably to or nearly to atmospheric pressure, while powering the generator  68  to produce electricity. After the air is expanded by the secondary expander  66 , it is also directed to the outlet  28  to be discharged to the atmosphere  30 . 
         [0034]    Through reconfiguration, the embodiment of  FIG. 1  can also work in a cooling capacity in its standard heating/cooling mode. There are many ways to reconfigure the system. One way to switch the system to the cooling operating mode is to rotate the vane-type device  36  by one hundred and eighty degrees (180°). In another technique, the rotor  42  could be moved in a radially upward direction (i.e., shifted upward) while the stator housing  38  remains stationary. Both of these reconfiguration methods effectively transform the compression chambers  48  into the expansion chambers  50  and vice versa. When operating in the cooling operating mode, the pump  60  first propels the atmospheric air into the expansion chambers  50  of the vane-type device  36  to reduce the pressure and temperature of the air. The combustion chamber  62  is dormant. The cooled air receives heat from the heat exchanger  32  to cool the target space  22 . The air is then re-pressurized in the compression chambers  48  of the vane-type device  36 , preferably to atmospheric pressure, before being dispensed to the atmosphere  30  through the outlet  28 . 
         [0035]    The vane-type device  36  can also work in a closed loop system  70 , as generally shown in  FIG. 2 . In the closed loop system  70 , the working fluid may be air or a refrigerant. Like the open-loop system of  FIG. 1 , the compression chamber inlet  52  and expansion chamber outlet  58  are generally longitudinally aligned with one another for simultaneously communicating with the same chamber  48 ,  50 . A high-pressure side heat exchanger  72  is fluidly connected to the vane-type device  36  through the compression chamber outlet  54  and the expansion chamber inlet  56 . A low-pressure side heat exchanger  74  is fluidly connected to the vane-type device  36  through the expansion chamber outlet  58  and the compression chamber inlet  52 . 
         [0036]    The closed loop system  70   FIG. 2  has two operating modes: a first operating mode and a second operating mode. Either the high pressure side heat exchanger  72  or the low-pressure side heat exchanger  74  may be disposed in a target space to be selectively heated or cooled or outside of the target space in the atmosphere. 
         [0037]    In the first operating mode, the rotor  42  rotates in a first direction, causing the pressure and temperature of the working fluid in the compression chambers  48  to increase as the volume of those compression chambers  48  decreases. That working fluid then flows into the high-pressure side heat exchanger  72  where it dissipates heat to either the target space or the atmosphere. The pressurized and cooled working fluid then flows into the expansion chambers  50  through the expansion chamber inlet  56 . In the expansion chambers  50 , the temperature and the pressure of the working fluid decrease as the volume of the expansion chambers  50  increases. The working fluid leaves the expansion chambers  50  through the expansion chamber outlet  58  and flows to the low-pressure side heat exchanger  74 . In the low-pressure side heat exchanger  74 , the working fluid receives heat from either the target space or the atmosphere before flowing back into the compression chambers  48 . 
         [0038]    Similar to the open loop embodiment of  FIG. 1 , the vane-type device  36  of  FIG. 2  can be switched to the second operating mode through reconfiguring. Specifically, the vane-type device  36  can be rotated by one hundred and eighty degrees (180°), or the rotor  42  could be moved radially within the stator housing  38 . This reconfiguring effectively reverses the functionality of the high-pressure side heat exchanger  72  and the low-pressure side heat exchanger  74 . In other words, the low-pressure side heat exchanger  74  becomes the high-pressure side heat exchanger  72  and dissipates heat, and the high-pressure side heat exchanger  32 ,  72  becomes the low-pressure side heat exchanger  74  and receives heat. 
         [0039]      FIG. 3  shows the vane-type device  36  in a cooling open-loop system. Similar to the embodiment of  FIG. 1 , air is used as the working fluid in the embodiment of  FIG. 3 . Unlike the embodiment of  FIG. 1 , the inlet  26  and the outlet  28  are disposed in the target space  22  for using air from the target space  22  as the working fluid. In the embodiment of  FIG. 3 , the compression chamber inlet  52  of the stator housing  38  is generally longitudinally aligned with the expansion chamber outlet  58  of the stator housing  38 . A heat exchanger  32  disposed in the atmosphere  30  is fluidly connected to the vane-type device  36  through the compression chamber outlet  54  and the expansion chamber inlet  56 . In operation, the air in the target space  22  enters the flow path  24  through the inlet  26 , and the blower propels the air into the vane-type device  36  through the compression chamber inlet  52 . The pressure and temperature of the air increase as the volume of the compression chambers  48  decreases. The air leaves the vane-type device  36  through the compression chamber outlet  54  and flows to the heat exchanger  32 . In the heat exchanger  32 , the warmed and pressurized air dispenses heat to the atmosphere  30  before flowing back into the vane-type device  36  through the expansion chamber inlet  56 . In the vane-type device  36 , the pressure and temperature of the air decrease as the volume of the expansion chambers  50  increases. The air entering the vane-type device  36  then pushes the cooled and depressurized air out of the vane-type device  36  through the expansion chamber outlet  58 . The air then exits the flow path  24  through the outlet  28  at a cooler temperature than it was when entering the flow path  24 , thereby cooling the target space  22 . 
         [0040]      FIG. 4  shows the vane-type device  36  in a heating open loop system. Similar to the embodiment of  FIG. 3 , the inlet  26  and the outlet  28  are disposed in the target space  22  for using the air in the target space  22  as the working fluid. In the embodiment of  FIG. 4 , the expansion chamber inlet  56  of the stator housing  38  is generally longitudinally aligned with the compression chamber outlet  54  of the stator housing  38 , and the compression chamber inlet  52  of the stator housing  38  is generally longitudinally aligned with the expansion chamber outlet  58  of the stator housing  38 . A heat exchanger  32  disposed in the atmosphere  30  is fluidly connected to the expansion chamber outlet  58  and the compression chamber inlet  52 . In operation, the air of the target space  22  enters the flow path  24  through the inlet  26 , and the blower propels the air into the vane-type device  36  through the expansion chamber inlet  56 . The pressure and temperature of the air decrease as the volume of the expansion chambers  50  increases. The air leaves the vane-type device  36  through the expansion chamber outlet  58  and flows to the heat exchanger  32 . In the heat exchanger  32 , the cooled and depressurized air receives heat from the atmosphere  30  before being propelled back into the vane-type device  36  through the compression chamber inlet  52  by another pump  60 . The warmed and still depressurized air entering the vane-type device  36  through the compression chamber inlet  52  also pushes the cooled and depressurized air out of the vane-type device  36  through the expansion chamber outlet  58 . In the vane-type device  36 , the pressure and temperature of the air increase as the volume of the compression chambers  48  decreases. The air entering the vane-type device  36  through the expansion chamber inlet  56  then pushes the warmed and re-pressurized air out of the vane-type device  36  through the compression chamber outlet  54 . The air then exits the flow path  24  through the outlet  28  at a warmer temperature than it was when entering the flow path  24 , thereby warming the target space  22 . 
         [0041]    An open-loop air aspirated hybrid heat pump and heat engine system  20  having a compressor  76  separated from the expander  78  is generally shown in  FIG. 5 . Similar to the embodiment of  FIG. 1 , atmospheric air is used as the working fluid in the embodiment of  FIG. 5 . In the embodiment of  FIG. 5 , the heat exchanger  32  is disposed in the target space  22  for transferring heat between the air in the flow path  24  and the target space  22 , and the inlet  26  and the outlet  28  are disposed outside of the target space  22  in the atmosphere  30 . A compressor  76  is disposed in the flow path  24  between the inlet  26  and the heat exchanger  32  for compressing and delivering the air from the inlet  26  to the heat exchanger  32 . An expander  78  is disposed in the flow path  24  between the heat exchanger  32  and the outlet  28  for expanding (i.e. depressurizing) and delivering the air from the heat exchanger  32  to the outlet  28 . In the exemplary embodiment, the compressor  76  and expander  78  are both vane-type pumps having a cylindrically shaped stator  38  and a rotor  42  rotatably disposed within the stator  38 . A plurality of spring-loaded vanes  46  project outwardly from the rotor  42  to slidably engage the inner wall  44  of the stator  38 . However, it should be appreciated that the compressor  76  and the expander  78  could be any type of pumps. 
         [0042]    An energy receiving device is mechanically connected to the expander  78  for harnessing potential energy from the air in the flow path  24  as will be discussed in further detail below. In the exemplary embodiment, the energy receiving device is a generator  68  for generating electricity. The electricity can then be used immediately, stored in batteries or inserted into the power grid. Alternatively or additionally, the energy receiving device could be a mechanical connection between the expander  78  and the compressor  76  for powering the compressor  76  with the energy reclaimed from the air in the flow path  24 . The energy receiving device could also be any other device for harnessing the energy produced by the expander  78 . 
         [0043]    A controller  82  is in communication with the compressor  76  and the expander  78  for controlling the hybrid heat pump and heat engine system  20 . The controller  82  manipulates or switches the system  20  between different operating modes: a standard heating/cooling mode (in which the target space  22  can be either heated or cooled), and a high heating mode (in which the target space  22  is heated). The operating mode may be selected by a person, or the controller  82  can be coupled to a thermostat for automatically keeping the target space  22  at a desired temperature. 
         [0044]    In reference to  FIG. 5 , the working fluid (e.g., air) travels through the flow path  24  in a clockwise direction. In the standard cooling operating mode, the controller  82  directs the compressor  76  to operate at a low speed and the expander  78  to operate at a higher speed. What follows is that the compressor  76  functions similarly to a valve separating the air downstream of the compressor  76  from the air at the inlet  26  of the flow path  24 . The expander  78  then pulls the air along the flow path  24  by reducing the pressure of the air from the compressor  76  to the expander  78 . Persons skilled in the art will appreciate that the temperature of the air leaving the compressor  76  will decrease as the pressure decreases. In other words, both the pressure and temperature of the air on the downstream side of the compressor  76  are reduced when compared to the pressure and temperature of the air at the inlet. The depressurized and cooled air then flows through the heat exchanger  32 , which transfers heat from the target space  22  to the air in the flow path  24  to cool the target space  22 . After leaving the heat exchanger  32 , the expander  78  propels the air out of the flow path  24  through the outlet  28 . Alternatively, the direction of the air may be reversed to flow in a counter-clockwise direction if this makes better use of the devices chosen with the final engineering targets in mind. In the cooling operating mode, the energy receiving device may be mechanically connected to the compressor  76  for harnessing the potential pressure energy from the air flowing through the compressor  76 . 
         [0045]    In the standard heating mode, the controller  82  directs the compressor  76  to compress the air from the inlet to increase the pressure and the temperature of the air, as will be understood by those skilled in the art. The pressurized and warmed air then flows through the flow path  24  to the heat exchanger  32 . The heat exchanger  32  dispenses heat to the target space  22  to warm the target space  22 . Although the air in the flow path  24  is cooled by the heat exchanger  32 , the air remains pressurized when compared to the air entering the flow path  24 . This difference in pressure represents potential energy, which can be harnessed. The generator  68 , which is coupled to the expander  78 , harnesses this potential energy while the expander  78  expands the pressurized air to reduce the pressure of the air. Preferably, the air is expanded back to the same pressure at which it entered the flow path  24 . Following the expansion, the air is discharged from the flow path  24  through the outlet  28 . 
         [0046]    In the high heating mode, the compressor  76  receives air aspirated from the inlet  26  and then compresses the air to increase its pressure and also its temperature (in compliance with relevant thermodynamic gas laws). The pressurized and high temperature air then flows through the flow path  24  to the combustion chamber  62 , which mixes a suitable fuel with the air and then combusts the mixture. The combustion of the fuel and air mixture further increases both the pressure and the temperature of the air in the flow path  24 . The pressurized and heated air then flows through the heat exchanger  32  and dispenses heat to the target space  22 . Air leaving the heat exchanger  32  in the high heating mode remains substantially highly pressurized relative to the ambient air pressure, and therefore represents a valuable amount of potential energy. The generator  68  maybe of any suitable type that is effective to convert this potential energy into another form, such as electricity and/or mechanical energy. This potential energy may be harnessed while the expander  78  expands the air to reduce the pressure of the air, or accumulated for conversion at a later time. In other words, any residual pressure energy put into the air through the initial compression and combustion processed is subsequently re-claimed by the generator  68 . Once the potential energy has been reclaimed, the low pressure air is then discharged from the flow path  24  through the outlet  28  back into the environment  30 . 
         [0047]    Obviously, many modifications and variations of the present invention are possible in light of the above teachings and may be practiced otherwise than as specifically described while within the scope of the appended claims. These antecedent recitations should be interpreted to cover any combination in which the inventive novelty exercises its utility. The use of the word “said” in the apparatus claims refers to an antecedent that is a positive recitation meant to be included in the coverage of the claims whereas the word “the” precedes a word not meant to be included in the coverage of the claims. In addition, the reference numerals in the claims are merely for convenience and are not to be read in any way as limiting.