Abstract:
A device ( 301 ) is provided which includes a Peltier device ( 303 ); a heat sink ( 305 ) in thermal contact with the Peltier device; and a synthetic jet ejector ( 307, 309 ) which directs a synthetic jet ( 319, 321 ) onto or adjacent to a surface of the heat sink.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/611,863, filed Mar. 16, 2012, having the same title and the same inventors, and which is incorporated herein in its entirety. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present disclosure relates generally to synthetic jet ejectors, and more particularly to systems and methods for thermal management which utilize synthetic jet ejectors in conjunction with Peltier coolers. 
       BACKGROUND OF THE DISCLOSURE 
       [0003]    A variety of thermal management devices are known to the art, including conventional fan based systems, piezoelectric systems, and synthetic jet ejectors. The latter type of system has emerged as a highly efficient and versatile thermal management solution, especially in applications where thermal management is required at the local level. 
         [0004]    Various examples of synthetic jet ejectors are known to the art. Earlier examples are described in U.S. Pat. No. 5,758,823 (Glezer et al.), entitled “Synthetic Jet Actuator and Applications Thereof”; U.S. Pat. No. 5,894,990 (Glezer et al.), entitled “Synthetic Jet Actuator and Applications Thereof”; U.S. Pat. No. 5,988,522 (Glezer et al.), entitled Synthetic Jet Actuators for Modifying the Direction of Fluid Flows”; U.S. Pat. No. 6,056,204 (Glezer et al.), entitled “Synthetic Jet Actuators for Mixing Applications”; U.S. Pat. No. 6,123,145 (Glezer et al.), entitled Synthetic Jet Actuators for Cooling Heated Bodies and Environments”; and U.S. Pat. No. 6,588,497 (Glezer et al.), entitled “System and Method for Thermal Management by Synthetic Jet Ejector Channel Cooling Techniques”. 
         [0005]    Further advances have been made in the art of synthetic jet ejectors, both with respect to synthetic jet ejector technology in general and with respect to the applications of this technology. Some examples of these advances are described in U.S. 20100263838 (Mahalingam et al.), entitled “Synthetic Jet Ejector for Augmentation of Pumped Liquid Loop Cooling and Enhancement of Pool and Flow Boiling”; U.S. 20100039012 (Grimm), entitled “Advanced Synjet Cooler Design For LED Light Modules”; U.S. 20100033071 (Heffington et al.), entitled “Thermal management of LED Illumination Devices”; U.S. 20090141065 (Darbin et al.), entitled “Method and Apparatus for Controlling Diaphragm Displacement in Synthetic Jet Actuators”; U.S. 20090109625 (Booth et al.), entitled Light Fixture with Multiple LEDs and Synthetic Jet Thermal Management System“; U.S. 20090084866 (Grimm et al.), entitled Vibration Balanced Synthetic Jet Ejector”; U.S. 20080295997 (Heffington et al.), entitled Synthetic Jet Ejector with Viewing Window and Temporal Aliasing”; U.S. 20080219007 (Heffington et al.), entitled “Thermal Management System for LED Array”; U.S. 20080151541 (Heffington et al.), entitled “Thermal Management System for LED Array”; U.S. 20080043061 (Glezer et al.), entitled “Methods for Reducing the Non-Linear Behavior of Actuators Used for Synthetic Jets”; U.S. 20080009187 (Grimm et al.), entitled “Moldable Housing design for Synthetic Jet Ejector”; U.S. 20080006393 (Grimm), entitled Vibration Isolation System for Synthetic Jet Devices”; U.S. 20070272393 (Reichenbach), entitled “Electronics Package for Synthetic Jet Ejectors”; U.S. 20070141453 (Mahalingam et al.), entitled “Thermal Management of Batteries using Synthetic Jets”; U.S. 20070096118 (Mahalingam et al.), entitled “Synthetic Jet Cooling System for LED Module”; U.S. 20070081027 (Beltran et al.), entitled “Acoustic Resonator for Synthetic Jet Generation for Thermal Management”; U.S. 20070023169 (Mahalingam et al.), entitled “Synthetic Jet Ejector for Augmentation of Pumped Liquid Loop Cooling and Enhancement of Pool and Flow Boiling”; U.S. 20070119573 (Mahalingam et al.), entitled “Synthetic Jet Ejector for the Thermal Management of PCI Cards”; U.S. 20070119575 (Glezer et al.), entitled “Synthetic Jet Heat Pipe Thermal Management System”; U.S. 20070127210 (Mahalingam et al.), entitled “Thermal Management System for Distributed Heat Sources”; U.S. 20070141453 (Mahalingam et al.), entitled “Thermal Management of Batteries using Synthetic Jets”; U.S. Pat. No. 7,252,140 (Glezer et al.), entitled “Apparatus and Method for Enhanced Heat Transfer”; U.S. Pat. No. 7,606,029 (Mahalingam et al.), entitled “Thermal Management System for Distributed Heat Sources”; U.S. Pat. No. 7,607,470 (Glezer et al.), entitled “Synthetic Jet Heat Pipe Thermal Management System”; U.S. Pat. No. 7,760,499 (Darbin et al.), entitled “Thermal Management System for Card Cages”; U.S. Pat. No. 7,768,779 (Heffington et al.), entitled “Synthetic Jet Ejector with Viewing Window and Temporal Aliasing”; U.S. Pat. No. 7,784,972 (Heffington et al.), entitled “Thermal Management System for LED Array”; and U.S. Pat. No. 7,819,556 (Heffington et al.), entitled “Thermal Management System for LED Array”. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIGS. 1A-1C  are illustrations depicting the manner in which a synthetic jet actuator operates. 
           [0007]      FIG. 2  is a schematic diagram of a Peltier element. 
           [0008]      FIG. 3  is an illustration of a top view of a first embodiment of a device which utilizes synthetic jets to cool a Peltier cooler. 
           [0009]      FIG. 4  is a side view of  FIG. 3 . 
           [0010]      FIG. 5  is an illustration of a top view of a second embodiment of a device which utilizes synthetic jets to cool a Peltier cooler. 
           [0011]      FIG. 6  is a side view of  FIG. 5 . 
           [0012]      FIG. 7  is an illustration of a top view of a third embodiment of a device which utilizes synthetic jets to cool a Peltier cooler. 
           [0013]      FIG. 8  is a side view of  FIG. 7 . 
           [0014]      FIG. 9  is an illustration of a thermoelectric module which utilizes synthetic jets to cool a heat source. 
           [0015]      FIG. 10  is an illustration of a thermoelectric module which utilizes synthetic jet ejectors powered by waste heat to cool a heat source. 
       
    
    
     SUMMARY OF THE DISCLOSURE 
       [0016]    In one aspect, a thermal management system is provided which comprises (a) a Peltier device; (b) a heat sink in thermal contact with said Peltier device; and (c) a synthetic jet ejector which directs a synthetic jet onto or adjacent to a surface of said heat sink. 
         [0017]    In another aspect, a thermal management system is provided which comprises (a) a Peltier device having first and second surfaces; (b) a heat source disposed on said first surface; and (c) a synthetic jet ejector which directs a synthetic jet onto or adjacent to said second surface. 
         [0018]    In a further aspect, a method for thermally managing a heat source is provided which comprises (a) providing a thermal management system comprising a Peltier device, a heat sink which is disposed on a first surface of said Peltier device, a heat source which is disposed on a second surface of said Peltier device, and a synthetic jet ejector which directs a synthetic jet onto or adjacent to a surface of said heat sink; and (b) operating the Peltier device such that a temperature gradient is established between said first and second surfaces. 
       DETAILED DESCRIPTION 
       [0019]    The systems, devices and methodologies disclosed herein utilize synthetic jet actuators or synthetic jet ejectors. Prior to describing these systems, devices and methodologies, a brief explanation of a typical synthetic jet ejector, and the manner in which it operates to create a synthetic jet, may be useful. 
         [0020]      FIG. 1  illustrates the operation of a typical synthetic jet ejector in forming a synthetic jet. As seen therein, the synthetic jet ejector  101  comprises a housing  103  which defines and encloses an internal chamber  105 . The housing  103  and chamber  105  may take virtually any geometric configuration, but for purposes of discussion and understanding, the housing  103  is shown in cross-section in  FIG. 1  to have a rigid side wall  107 , a rigid front wall  109 , and a rear diaphragm  111  that is flexible to an extent to permit movement of the diaphragm  111  inwardly and outwardly relative to the chamber  105 . The front wall  109  has an orifice  113  therein which may be of various geometric shapes. The orifice  113  diametrically opposes the rear diaphragm  111  and fluidically connects the internal chamber  105  to an external environment having ambient fluid  115 . 
         [0021]    The movement of the flexible diaphragm  111  may be achieved with a voice coil or other suitable actuator, and may be controlled by a suitable control system  117 . The diaphragm  111  may also be equipped with a metal layer, and a metal electrode may be disposed adjacent to, but spaced apart from, the metal layer so that the diaphragm  111  can be moved via an electrical bias imposed between the electrode and the metal layer. Moreover, the generation of the electrical bias can be controlled by any suitable device including, but not limited to, a computer, logic processor, or signal generator. The control system  117  can cause the diaphragm  111  to move periodically or to modulate in time-harmonic motion, thus forcing fluid in and out of the orifice  113 . 
         [0022]    Alternatively, a piezoelectric actuator could be attached to the diaphragm  111 . The control system would, in that case, cause the piezoelectric actuator to vibrate and thereby move the diaphragm  111  in time-harmonic motion. The method of causing the diaphragm  111  to modulate is not particularly limited to any particular means or structure. 
         [0023]    The operation of the synthetic jet ejector  101  will now be described with reference to  FIGS. 1   b - 1   c.    FIG. 1   b  depicts the synthetic jet ejector  101  as the diaphragm  111  is controlled to move inward into the chamber  105 , as depicted by arrow  125 . The inward motion of the diaphragm  111  reduces the volume of the chamber  105 , thus causing fluid to be ejected through the orifice  113 . As the fluid exits the chamber  105  through the orifice  113 , the flow separates at the (preferably sharp) edges of the orifice  113  and creates vortex sheets  121 . These vortex sheets  121  roll into vortices  123  and begin to move away from the edges of the orifice  109  in the direction indicated by arrow  119 . 
         [0024]      FIG. 1   c  depicts the synthetic jet ejector  101  as the diaphragm  111  is controlled to move outward with respect to the chamber  105 , as depicted by arrow  127 . The outward motion of the diaphragm  111  causes the volume of chamber  105  to increase, thus drawing ambient fluid  115  into the chamber  105  as depicted by the set of arrows  129 . The diaphragm  111  is controlled by the control system  117  so that, when the diaphragm  111  moves away from the chamber  105 , the vortices  123  are already removed from the edges of the orifice  113  and thus are not affected by the ambient fluid  115  being drawn into the chamber  105 . Meanwhile, a jet of ambient fluid  115  is synthesized by the vortices  123 , thus creating strong entrainment of ambient fluid drawn from large distances away from the orifice  109 . 
         [0025]    Cooling systems are also known which rely on thermoelectric cooling as implemented by a thermoelectric module. Such systems—which are variously referred to as Peltier coolers, Peltier heaters, Peltier devices, Peltier heat pumps, solid state refrigerators, thermoelectric coolers (TECs), or thermoelectric heat pumps—use the Peltier effect to create a heat flux between the junction formed between two different types of materials. These systems are typically implemented as solid-state active heat pumps which transfer heat from one side of the device to the other side against a temperature gradient (from cold to hot) when direct current runs through the system, and which consequently consume electrical energy as they do so. Although Peltier devices may also be used for heating, most applications of these devices to date have focused on cooling (refrigeration). 
         [0026]      FIG. 2  is a schematic diagram of a typical Peltier cooling device  201 . The device  201  comprises an electrically active layer  203  comprising a plurality of adjacent P-regions  205  and N-regions  207  which are sandwiched between first and second conductive layers  209 . The electrically conductive layers  209  are in electrical contact with first  211  and second  213  terminals and are capped, respectively, with first  215  and second  217  thermally conductive layers. The first  215  and second  217  thermally conductive layers form the cold and hot sides of the device, respectively. 
         [0027]    The thermoelectric legs in the Peltier cooling device  201  are thermally in parallel and electrically in series. In a Peltier cooling device, electric power is used to generate a temperature difference between the two sides (that is, the first  215  and second  217  thermally conductive layers) of the device. The thermoelectric performance of the device is typically a function of ambient temperature, hot and cold side heat exchanger (heat sink) performance, thermal load, Peltier module (thermopile) geometry, and Peltier electrical parameters. 
         [0028]    It has now been found that synthetic jet ejectors may be used in conjunction with Peltier devices to yield a variety of useful thermal management systems. In a preferred embodiment, such systems utilize a heat sink to spread heat from the hot side of a Peltier device, where it may be dissipated through the use of synthetic jets. 
         [0029]      FIGS. 3-4  illustrate a first particular, non-limiting embodiment of a thermal management system which utilizes a Peltier device in conjunction with one or more synthetic jet ejectors. The system  301  depicted therein comprises a Peltier device  303 , a heat sink  305  and first  307  and second  309  synthetic jet ejectors. The heat sink  305  is equipped with a plurality of heat fins  311  which define a plurality of channels  313  such that each channel  313  is formed by a pair of adjacent heat fins  311 . The first  307  and second  309  synthetic jet ejectors in the embodiment depicted are disposed at first  315  and second  317  opposing ends of the heat sink  305 , respectively. 
         [0030]    In operation, the first  307  and second  309  synthetic jet ejectors generate first  319  and second  321  respective sets of synthetic jets which are directed (possibly with the use of nozzles, distributors, manifolds, or other accoutrements) in opposing directions and away from the middle of the heat sink  305 . Typically, each synthetic jet in the first  319  and second  321  sets of synthetic jets is directed into one of the plurality of channels  313 , so that each channel  313  has synthetic jets of opposing orientation formed therein. Consequently, a flow of air is created which moves into, and in a direction generally perpendicular to, the center of the heat sink  305  as depicted in  FIG. 4 . In some embodiments, the heat sink  305  may be encased in a housing, and one or more apertures may be provided in the housing near the center of the heat sink  305  to permit or direct a flow of air into the heat sink  305 . 
         [0031]      FIGS. 5-6  illustrate a second particular, non-limiting embodiment of a thermal management system which utilizes a Peltier device in conjunction with one or more synthetic jet ejectors. The system  401  depicted therein comprises a Peltier device  403 , a heat sink  405  and first  407  and second  409  synthetic jet ejectors. The heat sink  405  is equipped with a plurality of heat fins  411  which define a plurality of channels  413  such that each channel  413  is formed by a pair of adjacent heat fins  411 . The first  407  and second  409  synthetic jet ejectors in the embodiment depicted are disposed at first  415  and second  417  opposing ends of the heat sink  405 , respectively. 
         [0032]    In operation, the first  407  and second  409  synthetic jet ejectors generate first  419  and second  421  respective sets of synthetic jets which are directed (possibly with the use of nozzles, distributors, manifolds, or other accoutrements) in opposing directions and towards the middle of the heat sink  405 . Typically, each synthetic jet in the first  419  and second  421  sets of synthetic jets is directed into one of the plurality of channels  413 , so that each channel  413  has synthetic jets of opposing orientation formed therein. Consequently, a flow of air is created which moves out from, and in a direction generally perpendicular to, the center of the heat sink  405  as depicted in  FIG. 6 . In some embodiments, the heat sink  405  may be encased in a housing, and one or more apertures may be provided in the housing near the center of the heat sink  405  to permit or direct a flow of air away from the heat sink  405 . 
         [0033]      FIGS. 7-8  illustrate a third particular, non-limiting embodiment of a thermal management system which utilizes a Peltier device in conjunction with one or more synthetic jet ejectors. The system  501  depicted therein comprises a Peltier device  503 , a heat sink  505  and a synthetic jet ejector  507 . The heat sink  505  is equipped with a plurality of heat fins  511  which define a plurality of channels  513  such that each channel  513  is formed by a pair of adjacent heat fins  511 . The synthetic jet ejector  507  in the embodiment depicted is disposed at a first  515  end of the heat sink  505 , respectively. 
         [0034]    In operation, the synthetic jet ejector  507  generates a set of synthetic jets which are directed (possibly with the use of nozzles, distributors, manifolds, or other accoutrements) along the longitudinal axes of the channels  513 . Typically, each synthetic jet is directed into one of the plurality of channels  513 . Consequently, a flow of air is created which moves in a direction generally parallel to the longitudinal axes of the channels  513  as depicted in  FIG. 8 . As in the previously described embodiments, the synthetic jets create turbulence in the channels  513  which disrupts the boundary layer around the surfaces of the heat fins  511 , thus facilitating the dissipation of heat from the heat sink  505  to the ambient environment. In some embodiments, the heat sink  505  may be encased in a housing, and one or more apertures may be provided in the housing on the opposite end from the synthetic jet ejector  507  to permit or direct a flow of air away from the heat sink  505 . 
         [0035]      FIG. 9  illustrates a fourth particular, non-limiting embodiment of a thermal management system which utilizes a Peltier device in conjunction with one or more synthetic jet ejectors. The system  601  depicted therein comprises a Peltier device  603 , a heat sink  605  and a synthetic jet ejector  607 . The heat sink  605  may be of various types, including the type described in the previous embodiments. 
         [0036]    In this particular embodiment, the Peltier device  603  is placed in contact with a heat source  604  such that the cold side of the Peltier device  603  is in contact with the heat source  604 . When power is supplied to the Peltier device  603 , a temperature gradient is setup across it. The hot side of the Peltier device  603  is then cooled with the synthetic jet ejector  607 , with or without the heat sink  605  being attached to the Peltier device  603 . 
         [0037]      FIG. 10  illustrates a fifth particular, non-limiting embodiment of a thermal management system which utilizes a Peltier device in conjunction with one or more synthetic jet ejectors. The system  701  depicted therein comprises a Peltier device  703 , a heat sink  705  and a synthetic jet ejector  707 . The heat sink  705  may be of various types, including the type described in the previous embodiments. 
         [0038]    In this particular embodiment, and unlike the previous embodiment, the Peltier device  703  is placed in contact with a heat source  704  such that the warm side of the Peltier device  703  is in contact with the heat source  704 . When power is supplied to the Peltier device  703 , a temperature gradient is setup across it. The cool side of the Peltier device  703  is then exposed to the synthetic jet ejector  707 , with or without the heat sink  705  being attached to the Peltier device  703 . The synthetic jet ejector  707  is used to cool one side of the Peltier device  703  to maintain a constant temperature gradient within the limits of the electronics, and the temperature gradient across the Peltier device  703  creates a voltage which is stored and resupplied to the synthetic jet ejector  707 . 
         [0039]    Various modifications may be made to the above noted devices and methodologies without departing from the teachings herein. For example, various types of synthetic jet ejectors may be utilized, including those with voice coil actuators as well as those with piezoceramic actuators. Moreover, these devices and methodologies may be utilized in various end use applications and in various types of devices. In addition, various heat sinks, nozzles and manifolds having various configurations and geometries may be utilized in these devices and methodologies. 
         [0040]    The above description of the present invention is illustrative, and is not intended to be limiting. It will thus be appreciated that various additions, substitutions and modifications may be made to the above described embodiments without departing from the scope of the present invention. Accordingly, the scope of the present invention should be construed in reference to the appended claims.