Abstract:
Techniques for the removal of waste heat from solid state, semiconductor devices (such as cooking or heating devices) are provided. In particular, techniques for conducting waste heat away from the device through a heat sink in contact with a cooling system are provided. In addition, a multi-head cooling system applicable to multiple solid state, semiconductor sources is provided.

Description:
[0001]    This application is based on and claims priority to U.S. Provisional Application No. 61/350,352, filed Jun. 1, 2010, which is incorporated herein by reference in its entirety. 
     
    
     FIELD 
       [0002]    The presently described embodiments relate, in general, to a novel system configuration(s) and associated methods for the removal of waste heat from solid state, semi-conductor array cooking systems and, in particular, to the conduction of the waste heat away from the devices array through a heat sink in contact with a cooling system. In addition, this application includes a design of a multi-head cooling system applicable to cool multiple solid state, semi-conductor array irradiation sources. 
       BACKGROUND 
       [0003]    The advantages of heating and cooking with irradiation produced by arrays of semi-conductor devices have been well documented. For example, a prior patent, U.S. Pat. No. 7,425,296, discloses such advantages. Increased device lifetime, greater output energy control, improved energy efficiency, compact size and improved repeatability are all desirable characteristics in heating, curing, and cooking processes intended for residential, commercial or industrial applications. The efficiency and lifetime of these devices, however, is closely related to the ability to successfully remove the waste heat produced during the conversion of electricity to electromagnetic or other irradiation energy. Indeed, the primary failure mode of any semi-conductor devices is the damage that can occur during overheating. 
         [0004]    Current cooling methodologies for semi-conductor of devices include metal heat sinks, forced air systems and closed and open pumped liquid heat exchanger systems. Metal heat sinks and forced air systems have the disadvantage of low cooling capacity, with the best possible temperature set at the local ambient temperature while pumped liquid systems require large reservoirs, bulky pumps and provide only low relative efficiency when maintaining the coolant temperature near or below ambient. The utility of vapor phase cooling for electronic circuit components and other power electronics that require removal of large amounts of waste heat have been around since the 1960s. 
         [0005]    The previous systems deal primarily with the design and implementation of two-phase cooling circuits, with at least one going so far as to specify the use of the cooling system for solid state circuit components. In addition, two-phase systems that are current commercially available are typically sized for industrial applications with typical capacities in the 10s of kilowatts. 
       BRIEF DESCRIPTION 
       [0006]    In one aspect of the presently described embodiments, the system comprises a mounting substrate to which the array of semi-conductor based radiation emitting devices is mounted on a first surface thereof, the mounting substrate including at least one of a first material having high thermal conductivity and a second material having electrical insulating features, a heat exchange body connected to a second surface of the mounting substrate, heat exchange fluid cavity within the heat exchange body operative to maintain a flow of heat exchange fluid in the heat exchange body, and, fluid connections provided to an inlet and an outlet of the heat exchange fluid cavity. 
         [0007]    In another aspect of the presently described embodiments, the system comprises a cooling system connected to the fluid connections. 
         [0008]    In another aspect of the presently described embodiments, the cooling system is at least one of a vapor phase cooling system, water-based cooling system, air based cooling system or refrigerant-based cooling system. 
         [0009]    In another aspect of the presently described embodiments, the semi-conductor based radiation emitting devices emit energy in narrow band in one of the infrared, ultraviolet and visible ranges. 
         [0010]    In another aspect of the presently described embodiments, the narrow band is less than 300 nm, full width half max. 
         [0011]    In another aspect of the presently described embodiments, the semi-conductor based radiation emitting devices emit energy in the microwave range. 
         [0012]    In another aspect of the presently described embodiments, the mounting substrate is formed of or contains at least one of copper material, diamond material, nano-conductor composite material or alloys thereof. 
         [0013]    In another aspect of the presently described embodiments, the mounting substrate and the heat exchange body are integral. 
         [0014]    In another aspect of the presently described embodiments, the system further comprises a controller operative to control a flow of fluid to the heat exchange fluid cavity. 
         [0015]    In another aspect of the presently described embodiments, the system further comprises at least one of a fluid regulator and a temperature sensor. 
         [0016]    In another aspect of the presently described embodiments, the array is two-dimensional. 
         [0017]    In another aspect of the presently described embodiments, the array is an X-by-Y array wherein both X and Y are greater than 1. 
         [0018]    In another aspect of the presently described embodiments, the system comprises a first array cooling subassembly including a first mounting substrate to which a first array of semi-conductor based radiation emitting devices is mounted on a first surface thereof, the mounting substrate including at least one of a first material having high thermal conductivity and a second material having electrical insulating features, a first heat exchange body connected to a second surface of the mounting substrate, a first heat exchange fluid cavity within the first heat exchange body operative to maintain a flow of heat exchange fluid in the first heat exchange body, and first fluid connections provided to an inlet and an outlet of the first heat exchange fluid cavity, and, a second array cooling subassembly including a second mounting substrate to which a second array of semi-conductor based radiation emitting devices is mounted on a first surface thereof, a second heat exchange body connected to a second surface of the mounting substrate, a second heat exchange fluid cavity within the second heat exchange body operative to maintain a flow of heat exchange fluid in the second heat exchange body, and second fluid connections provided to an inlet and an outlet of the second heat exchange fluid cavity. 
         [0019]    In another aspect of the presently described embodiments, the system further comprises a cooling system connected to the first array cooling subassembly and the second array cooling subassembly. 
         [0020]    In another aspect of the presently described embodiments, the first array cooling subassembly and the second array cooling subassembly are connected in parallel to the cooling system. 
         [0021]    In another aspect of the presently described embodiments, the first array cooling subassembly and the second array cooling subassembly are connected in series with the cooling system. 
         [0022]    In another aspect of the presently described embodiments, the first array cooling subassembly and the second array cooling subassembly are arranged relative to a work area to perform heating and cooking functions. 
         [0023]    In another aspect of the presently described embodiments, the work area is an oven cavity. 
         [0024]    In another aspect of the presently described embodiments, the work area is a heating zone. 
         [0025]    In another aspect of the presently described embodiments, the radiation emitting devices of the first array cooling subassembly and the second array cooling subassembly are of the same type. 
         [0026]    In another aspect of the presently described embodiments, the radiation emitting devices of the first array cooling subassembly and the second array cooling subassembly are of different types. 
         [0027]    In another aspect of the presently described embodiments, the first array cooling subassembly is connected to a first cooling system and the second array cooling subassembly is connected to a second cooling system. 
         [0028]    In another aspect of the presently described embodiments, the system further comprises a controller operative to control a flow of fluid to the first array cooling subassembly and the second array cooling subassembly. 
         [0029]    In another aspect of the presently described embodiments, the system further comprises at least one of a fluid regulator and a temperature sensor. 
         [0030]    In another aspect of the presently described embodiments, a method for providing cooling to an array of semi-conductor based radiation emitting devices disposed on an array cooling subassembly including a mounting substrate to which the array of radiation emitting devices is mounted on a first surface thereof, the mounting substrate including at least one of a first material having high thermal conductivity and a second material having electrical insulating features, a heat exchange body connected to a second surface of the mounting substrate, a heat exchange fluid cavity within the heat exchange body operative to maintain a flow of heat exchange fluid in the heat exchange body, fluid connections provided to an inlet and an outlet of the heat exchange fluid cavity, comprises receiving data at a controller, determining fluid flow parameters for the flow of heat exchange fluid in the heat exchange cavity based on the data, and, controlling the flow to the inlet of the heat exchange cavity based on the determined fluid flow parameters. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]      FIG. 1  is a system according to the presently described embodiments; 
           [0032]      FIG. 2  is a system according to the presently described embodiments; 
           [0033]      FIG. 3  is a system according to the presently described embodiments; 
           [0034]      FIG. 4  is a system according to the presently described embodiments; 
           [0035]      FIG. 5  is a system according to the presently described embodiments; 
           [0036]      FIG. 6  is a system according to the presently described embodiments; 
           [0037]      FIG. 7  is a system according to the presently described embodiments; and, 
           [0038]      FIG. 8  is a method according to the presently described embodiments. 
       
    
    
     DETAILED DESCRIPTION 
       [0039]    A purpose of the presently described embodiments is to apply a properly sized cooling system to solid state, semi-conductor based electromagnetic irradiation device arrays used in heating and curing applications. One such application involves systems for cooking food. Another application of the presently described embodiments is to systems using narrowband semi-conductor based radiant heating of plastic components, such as PET bottle preforms in a bottle blowing process. 
         [0040]    The contemplated cooling system may take a variety of forms including heat transfer fluid systems such as state change cooling systems (including vapor phase (or two phase) cooling systems), water based cooling systems (including systems using water mixtures including, e.g. ethylene glycol), air cooling systems or common refrigerant cooling systems (e.g. systems using chlorofluorocarbons (CFCs), hydro chlorofluorocarbons (HCFCs), butane, or propane). 
         [0041]    With reference to  FIG. 1 , a system  10  includes solid state, semi-conductor array radiation sources  12 . The sources  12  can be comprised of any one or combination of a variety of types of devices including laser diodes, solid state lasers, or other types of laser devices, LED&#39;s including power LED&#39;s, surface emitting devices including surface emitting laser devices, micro-wave semi-conductors, light emitting transistors (LET&#39;s) or other electromagnetic or RF producing semi-conductors. These devices or sources are arranged in arrays in at least one form. The arrays may take a variety of suitable configurations; however, in at least one configuration, the arrays are two-dimensional. Still further, the arrays may be configured as X-by-Y arrays, where both X and Y are greater than 1. The arrays may include devices (either within an array or in separate arrays) having center wavelengths separated by at least 150 nanometers. In at least one form, the sources may be semi-conductor irradiation emitting devices emitting energy or irradiation in a narrow band in the infrared, visible or ultraviolet ranges. These narrow bands, for example, may be less than 300 nanometers, full width half max. Also, in at least one form, the radiation sources are narrowband sources wherein the radiation emitted at narrow wavelength bands is selected to enhance the heating/cooking process, as described in, for example, U.S. Pat. No. 7,425,296, U.S. Ser. No. 11/448,630 (filed Jun. 7, 2006), U.S. Ser. No. 12/135,739 (filed Jun. 9, 2008), U.S. Ser. No. 12/718,919 (filed Mar. 5, 2010) and U.S. Ser. No. 12/718,899 (filed Mar. 5, 2010), all of which are incorporated herein by reference in their entirety, and others. 
         [0042]    As shown, the sources  12  may be mounted directly to a conductive or heat sink surface, or mounting substrate,  14 —with the opposite side directly in contact with a heat exchange body  16 . For ease of reference, the sources (or arrays of sources)  12 , the conductive surface or mounting substrate  14  and the heat exchange body  16  form an array cooling subassembly  11 . 
         [0043]    The sources  12  may be connected to the substrate  14  in any of a variety of manners. In one form, the arrays of the sources  12  are soldered to the substrate  14 . The substrate  14  may also then be soldered to the heat exchange body. Also, it should be appreciated that the heat exchange body and the mounting substrates (or conductive surfaces) may be separate elements or formed as a homogeneous unit. 
         [0044]    The mounting substrate  14  will, in at least one form, be made of material with high thermal conductivity (such as, but not limited to, copper, diamond, nano-conductor composites or alloys thereof, or materials having these components included therein) to reduce the thermal resistance between the temperature sensitive semi-conductor junction and the cooling elements. This substrate may also function as an electrical circuit for the solid state, semi-conductor emitters. In this way, the substrate may include an electrical insulation material (such as a diamond composite or ceramic material) or a heat spreader of suitable material (such as a diamond composite or nanomaterial composite) to improve performance. The substrate may be formed of a single layer or multiple layers to accomplish the above recited functionality. Accordingly, a layer may be provided to provide thermal conductivity and another layer may be provided to provide electrical insulation. Or, a material that is able to provide both features may be used. Also, it should be understood that the mounting substrate may, in some cases, include an electrically conductive layer or circuit board components or materials to facilitate proper circuit or electrical connections (e.g. for the sources). The mounting substrate will be sized to suit its functionality and the environment of its use. However, in one form, the mounting substrate is relatively thin, e.g. having a thickness in the range of hundreds of microns, or having layers wherein each layer has a thickness in the range of hundreds of microns. 
         [0045]    As shown, a cooling system  20  is, in one form, located remotely from the arrays to provide for improved, and possibly optimum, management of the removed waste heat. As noted above, the cooling system  20  may take a variety of forms. 
         [0046]    With reference now to  FIG. 2 , another view of the subassembly  11  of system  10  is shown. In this regard, the subassembly  11  includes sources  12 , which are shown as being positioned on a first surface of a mounting substrate  14  in an array fashion. The mounting substrate  14  is also connected via a second surface to the heat exchange body  16 . The heat exchange body  16  has a heat exchange fluid cavity  15  configured to maintain a flow of heat exchange fluid  19  therein. In this view, the plumbing or fluid connections  17  to the cooling system  20  are also illustrated, although, the cooling system  20  is not illustrated in  FIG. 2  for ease of illustration. The fluid connections  17  may take a variety of appropriate forms (e.g. may be formed of a variety of suitable material and have a variety of configurations and features) and are provided to an inlet and an outlet of the heat exchange fluid cavity  15 . As noted above, emitters or sources  12  may be attached to the mounting substrate  14  in a variety of manners, including soldering. It should also be appreciated that the emitters  12  may be connected or soldered to electrical traces (not shown) on the mounting substrate  14 . Also, as noted above, the mounting substrate  14  may be connected to the heat exchange body  16  in a variety of manners, including soldering. It should be understood that other connection techniques such as deposition (e.g. vapor deposition, sputtering, . . . etc.) or adhesive techniques may also be used. 
         [0047]    With reference to  FIG. 3 , a system  10 ′ shows that a properly sized cooling system  20 ′ is distributed across multiple arrays of solid state sources  12 ′ organized on corresponding mounting substrates or conductive surfaces  14 ′—which connect to corresponding heat exchange bodies  16 ′. Two (2) subassemblies  11 ′ are shown, but the number may vary according to the implementation. It should be appreciated that like numerals (differing only by a prime designation (′)) in  FIGS. 3 and 4  generally correspond to like elements of  FIGS. 1 and 2 . 
         [0048]    With reference more specifically to  FIG. 4 , the system  10 ′ shows that the multiple subassemblies  11 ′ are distributed relative to, e.g. around, a work area or cavity  18 ′ to perform, for example, suitable heating or cooking functions. The work area or cavity  18 ′ may correspond to a variety of different work environments including oven cavities, heating zones, . . . etc. Also, it should be understood that the number of subassemblies and their orientation relative to the work area may vary. For example, in another form, all subassemblies may be positioned on one side of the work area. The plumbing or fluid connections  17 ′ connect the subassemblies  11 ′ to a single heat exchanger or cooling system  20 ′. 
         [0049]    Furthermore, as noted above, the arrays could comprise multiple different types of solid state radiation sources such as those described in connection with  FIG. 1  (such as infrared and microwave emitters). With reference to  FIG. 5 , it will be appreciated that various radiation sources may be packaged in subassemblies such as subassemblies  511  and  513 —which, in at least one form, have a configuration which resembles the subassembly  11  of  FIG. 2 . As shown, subassembly  511  is connected back to the cooling system  520  via plumbing or fluid connection lines  517 . In this configuration, the subassembly  511  has sources of a first type TYPE 1 (e.g. infrared sources such as those described above that may emit in a narrow band) positioned thereon in an array. Likewise, subassembly  513  connects to cooling system  521  by way of plumbing or fluid connection line  517 . In this configuration, the subassembly  513  has sources of a second type TYPE 2 (e.g. microwave sources such as those described above that emit in the microwave range) positioned thereon in an array. These various radiation sources surround work area or cavity  518  as shown. To clarify, the cooling systems  520  and  521  may take a variety of forms, as described above. Also, the work area  518  generally corresponds to the work area  18 ′ described above. 
         [0050]    In a still further embodiment, the radiation sources  12  or arrays thereof may be arranged in series in the contemplated cooling system. In one form, such a series arrangement is advantageously implemented for vapor phase cooling systems, but has less advantages with other cooling systems where a parallel arrangement (e.g. such as that shown in  FIGS. 4 and 5 ) has more advantages. In this regard, with reference to  FIG. 6 , a system  610  is shown. The system  610  includes arrays cooling subassemblies  611  that resemble the subassemblies  11  described above and surround a work area or cavity  618  (which corresponds to work cavity  18 ′ described above). The subassemblies  611  are connected to the heat exchanger or cooling system  620  via plumbing or fluid connections  617 . As shown, the fluid connections or plumbing  617  is connected to the device arrays  611  in series fashion—e.g. where the outlet of one subassembly  611  is connected the inlet of a second subassembly  611 . 
         [0051]    It should also be appreciated that systems according to the presently described embodiments, such as the systems described in connection with  FIGS. 1  through  6 , may also include feedback features. Such feedback features may provide improved performance, particularly since the loads of different devices are unlikely to be the same. In this regard, the system may be provided with a monitoring system (e.g. temperature sensors, thermo-couples or the like, and a controller) to monitor the heat load of the radiation sources. The monitoring system may then redirect coolant based on the determined load. As an alternative, the monitoring system may redirect the coolant based on a predetermined or known duty cycle. 
         [0052]    In this regard, with reference now to  FIG. 7 , an example system  710  is illustrated. Although the system  710  generally resembles the system of  FIG. 4 , a feedback system as described may be implemented on any of the systems described in  FIGS. 1 through 6 . The system  710  includes subassemblies  711  that correspond to the subassemblies  11  described above and surround a work area or cavity  718  (that generally resembles work cavity or area  18 ′). The subassemblies  711  are connected to the cooling system  720  by way of plumbing or fluid connection  717 . Fluid regulators  722  are provided between the respective subassemblies  711  and the heat exchanger  720 . Also shown are sensors or thermo-couples  723  positioned, in one example configuration, at the outlet of the subassemblies  711 . The sensors or thermo-couples  723  may take a variety of forms. Also, a controller  724  is illustrated as being operatively connected to the cooling system  720  (which, as above, may take a variety of forms). The sensors  723  and the controller  724 , in one form, comprise the monitoring system as described above. It should be appreciated that the controller  724  may take a variety of forms, including a substantially dedicated controller for the cooling system or a controller for a heating or cooking system to which the presently described embodiments are applied. The controller may be implemented as hardware such as a computer or processor that executes routines using a variety of software techniques. In this way, methods according to the presently described embodiments (including the example method described in connection with  FIG. 8  below), may be implemented using a variety of hardware configurations, including storage media that is computer readable or machine readable (e.g. in a controller  724  using related sensors  723  and fluid regulators  722 , and appropriate memory devices and/or locations such as digital, magnetic or optical memories or drives), executing various routines to achieve functionality and/or execute steps or instructions of the methods contemplated by the presently described embodiments. 
         [0053]    In operation, with reference now to  FIG. 8 , an example flowchart for an example method  800  according to the presently described embodiments is shown. As illustrated, the controller  724  receives data (at  802 ). It should be appreciated that, in one form, the data may be obtained by reading sensors or thermocouples that measures any of a variety of temperature levels such as the temperature of the fluid exiting the subassemblies  711 , the temperature of the heat exchange body, and/or the temperatures of the arrays of sources. It should be appreciated that, in some cases, the sensors may not be required where prior knowledge of the heating or duty cycles may be used to regulate fluid flow. Such knowledge may also be used in conjunction with the data obtained by sensors to provide enhanced performance. 
         [0054]    In any case, the controller  724  uses the data available to it to determine fluid flow parameters (at  804 ). In at least one form, the fluid flow parameters include an amount of fluid that should be fed to the subassemblies  711  and/or a rate of flow of such fluid. These parameters may be calculated using a variety of techniques including using look-up tables or executing routines to calculate such parameters. The form of the tables and the routine and/or the calculation will vary from application to application. 
         [0055]    Once the parameters are determined, the controller  724  then sends signals to the fluid regulators  722  to control an amount or rate of fluid that is fed through the plumbing  717  to the sub-portions  711  (at  806 ). Such control of the fluid regulators may be accomplished using a variety of techniques, including through the cooling system or by way of more direct electronic control (e.g. wired or wireless) from the controller. 
         [0056]    The exemplary embodiment has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiment be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.