Abstract:
A heat exchanger for coupling to a device is described. The heat exchanger includes an inner layer configured for placement against at least one surface of the device, an outer layer opposite the inner layer, a fluid chamber defined between the outer layer and the inner layer, an inlet for directing a thermal transfer fluid into the fluid chamber, an outlet for receiving the thermal transfer fluid from the fluid chamber, and at least one filler within the fluid chamber. The filler is coupled to the outer layer and the inner layer and configured to control a flow of the thermal transfer fluid between the inlet and the outlet.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application No. 61/737,582 filed Dec. 14, 2012 and U.S. Provisional Application No. 61/759,109 filed Jan. 31, 2013, the entire disclosures of which are hereby incorporated by reference in their entireties. 
     
    
     FIELD 
       [0002]    This disclosure generally relates to temperature regulation, and more specifically, to methods and systems for regulating temperature using a multilayered heat exchanger. 
       BACKGROUND 
       [0003]    Various devices can benefit from temperature regulation. In particular, many electronic and/or electrical devices benefit from temperature reduction and/or limiting temperature increases. For example, photovoltaic (PV) modules are devices which convert solar energy into electricity. Some known PV modules convert around 85% of incoming sunlight into heat. During peak conditions, this can result in a heat-generation of 850 W/m 2  and PV module temperatures as high as 70° C. The electrical power produced by PV modules decreases linearly with increase in module temperature. For example, in bright sunlight, crystalline silicon PV modules may heat up to 20-30° C. above ambient temperature, resulting in a 10-15% reduction in power output relative to the rated power output for the PV module. Moreover, higher PV module temperatures may increase material degradation, such as thermal fatigue failure of interconnections between PV cells in the PV module. Accordingly, PV modules may benefit from reduced temperatures and/or from reducing a rate of increase in temperature. 
         [0004]    This Background section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
       BRIEF SUMMARY 
       [0005]    According to one aspect of this disclosure, a photovoltaic (PV) module includes a solar panel having a top surface and a bottom surface, and a heat exchanger in thermal communication with the bottom surface of the solar panel. The heat exchanger includes an outer layer, a fluid chamber defined between the outer layer and the bottom surface of the solar panel, an inlet for directing a thermal transfer fluid into the fluid chamber, an outlet for receiving the thermal transfer fluid from the fluid chamber, and at least one spacer within the fluid chamber. The spacer is configured to control a flow of the thermal transfer fluid between the inlet and the outlet. 
         [0006]    In another aspect, a PV system includes a fluid pump, a fluid heat exchanger configured to thermally alter a thermal transfer fluid and provide the thermal transfer fluid to the fluid pump, and a PV module coupled to the fluid pump and the fluid heat exchanger. The PV module is configured to receive the thermal transfer fluid from the pump. The PV module includes a solar panel having a top surface and a bottom surface, and a heat exchanger in thermal communication with the bottom surface of the solar panel. The heat exchanger includes a fluid chamber having at least one spacer within the fluid chamber. The heat exchanger is configured to receive the thermal transfer fluid from the fluid pump into the fluid chamber and output the thermal transfer fluid to the fluid heat exchanger after the thermal transfer fluid has passed through the fluid chamber. 
         [0007]    Yet another aspect is a heat exchanger for coupling to a device to regulate a temperature of the device. The heat exchanger includes an inner layer configured for placement against at least one surface of the device, an outer layer opposite the inner layer, a fluid chamber defined between the outer layer and the inner layer, an inlet for directing a thermal transfer fluid into the fluid chamber, an outlet for receiving the thermal transfer fluid from the fluid chamber, and at least one spacer within the fluid chamber. The spacer is coupled to the outer layer and the inner layer and configured to control a flow of the thermal transfer fluid between the inlet and the outlet. 
         [0008]    Various refinements exist of the features noted in relation to the above-mentioned aspects. Further features may also be incorporated in the above-mentioned aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated embodiments may be incorporated into any of the above-described aspects, alone or in any combination. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective view of an example PV module; 
           [0010]      FIG. 2  is a cross-sectional view of the PV module shown in  FIG. 1  taken along the line A-A; 
           [0011]      FIG. 3  is a cross-sectional view of an exemplary heat exchanger; 
           [0012]      FIG. 4  is a temperature regulation system including the heat exchanger shown in  FIG. 3 ; 
           [0013]      FIG. 5  is a cross-sectional illustration of an assembly including a heat exchanger attached to a PV module; 
           [0014]      FIG. 6  is a top view of an assembly including a heat exchanger integrated into a PV module; 
           [0015]      FIG. 7  is a cross sectional view of the assembly shown in  FIG. 6  taken along the line A-A in  FIG. 6 ; 
           [0016]      FIG. 8  is a top view of an exemplary stand-alone heat exchanger; 
           [0017]      FIG. 9  is a cross sectional view of heat exchanger shown in  FIG. 8  taken along the line B-B in  FIG. 8 ; 
           [0018]      FIG. 10  is a top view of a heat exchanger including a plurality of plastic spacers; 
           [0019]      FIG. 11  is a cross sectional view of heat exchanger shown in  FIG. 10  taken along the line C-C in  FIG. 10 ; 
           [0020]      FIG. 12  is a cross sectional view of an exemplary connection assembly for use as an inlet and/or outlet for a heat exchanger; and 
           [0021]      FIG. 13  is a heat exchanger coupled to a device. 
       
    
    
       [0022]    Like reference symbols in the various drawings indicate like elements. 
       DETAILED DESCRIPTION 
       [0023]    The embodiments described herein generally relate to temperature regulation and control. More specifically, embodiments described herein relate to methods and systems for regulating and controlling temperature using a multilayered heat exchanger. Specific embodiments are described herein with reference to photovoltaic (PV) modules. However, the teachings of the present disclosure may be applied to any device that may benefit from enhanced temperature regulation. Moreover, although various embodiments will be discussed with respect to cooling a device, it should be understood that the embodiments described herein may additionally, or alternatively, be used to heat a device with which they are used. 
         [0024]    Referring initially to  FIGS. 1 and 2 , a PV module is indicated generally at  100 . A perspective view of PV module  100  is shown in  FIG. 1 .  FIG. 2  is a cross sectional view of PV module  100  taken at line A-A shown in  FIG. 1 . PV module  100  includes a solar panel  102  and a frame  104  circumscribing solar panel  102 . 
         [0025]    Solar panel  102  includes a top surface  106  and a bottom surface  108  (shown in  FIG. 2 ). Edges  109  extend between top surface  106  and bottom surface  108 . In this embodiment, solar panel  102  is rectangular shaped. In other embodiments, solar panel  102  may have any suitable shape. 
         [0026]    As shown in  FIG. 2 , this solar panel  102  has a laminate structure that includes several layers  118 . Layers  118  may include for example glass layers, non-reflective layers, electrical connection layers, n-type silicon layers, p-type silicon layers, and/or backing layers. In other embodiments, solar panel  102  may have more or fewer, including one, layers  118 , may have different layers  118 , and/or may have different types of layers  118 . 
         [0027]    As shown in  FIG. 1 , frame  104  circumscribes solar panel  102 . Frame  104  is coupled to solar panel  102 , as best seen in  FIG. 2 . Frame  104  assists in protecting edges  109  of solar panel  102 . In this embodiment, frame  104  is constructed of four frame members  120 . In other embodiments frame  104  may include more or fewer frame members  120 . 
         [0028]    Exemplary frame  104  includes an outer surface  130  spaced apart from solar panel  102  and an inner surface  132  adjacent solar panel  102 . Outer surface  130  is spaced apart from and substantially parallel to inner surface  132 . In this embodiment, frame  104  is made of aluminum. More particularly, in some embodiments frame  104  is made of 6000 series anodized aluminum. In other embodiments, frame  104  may be made of any other suitable material providing sufficient rigidity including, for example, rolled or stamped stainless steel, plastic, or carbon fiber. 
         [0029]      FIG. 3  is a simplified cross-sectional view of an exemplary heat exchanger  300  according to the present disclosure. Heat exchanger  300  includes an inner layer  302 , a fluid layer  304 , and an outer layer  306 . In this embodiment, fluid layer  304  includes a chamber  305  and one or more spacers or spacing material (not shown in  FIG. 3 ) to maintain a substantially consistent separation between inner and outer layers  302  and  306 . The spacers are connected to inner layer  302  and outer layer  306  to, among other things, prevent bulging of inner or outer layer  302  or  306  when fluid is pumped into chamber  305  of fluid layer  304 . Seals  308  connect inner and outer layers  302  and  306  to provide a substantially water tight seal around fluid layer  304 , and more specifically around chamber  305 . Thus, a heat transfer fluid, such as water, oil, etc., may flow through fluid layer  304  to extract heat from a device with which heat exchanger  300  is used, without the fluid contacting the device. In some embodiments, seals  308  may be, additionally or alternatively, spacers or spacing material. Moreover, in some embodiments, seals  308  may be integrally formed with inner layer  302  and/or outer layer  306 . 
         [0030]    Inner layer  302  is the portion of heat exchanger  300  that will be in contact with the device to be temperature regulated by heat exchanger  300 . Accordingly, inner layer  302  is made from a material having relatively high thermal conductivity. Moreover, the material for inner layer  302  is selected to conform reasonably well to the surface of the device with which it will be used in order to provide sufficient thermal contact or thermal communication with the surface of the device. In this embodiment, inner layer  302  comprises a sheet that is suitably made of metal. In other embodiments, inner layer  302  may be an aluminum sheet. 
         [0031]    The thickness of inner layer  302  may be varied to suit different uses. Thicker sheets may be used to provide increased rigidity and thermal transfer, but with a corresponding decrease in flexibility and/or conformability. In some embodiments, inner layer  302  is a thin, metal foil. In one exemplary embodiment, inner layer  302  is a metal foil having a thickness of about 0.1 millimeter. Other embodiments may use thicker or thinner metal foils. The use of thinner materials for inner layer  302  may increase the flexibility of heat exchanger  300 , reduce the weight of heat exchanger  300 , and/or permit it to conform to more irregular shaped devices. In general, inner layer  302  may be constructed from any thermally conductive material of sufficient strength and impermeability to retain a heat transfer fluid within heat exchanger  300 . 
         [0032]    Outer layer  306  is the portion of heat exchanger  300  opposite the side of heat exchanger  300  that will be in contact with the device to be temperature regulated by heat exchanger  300  (i.e., opposite inner layer  302 ). In some embodiments, outer layer  306  is made of a material having relatively high thermal conductivity, such as a metal sheet or a metal foil, to permit heat to radiate from fluid layer  304  through outer layer  306 . In other embodiments, outer layer is fabricated from a material that is not particularly thermally conductive, such as a plastic sheet or film. The thickness of outer layer  306  may be varied to suit different uses. Thicker sheets may be used to provide increased rigidity and thermal transfer, but with a corresponding decrease in flexibility and/or conformability. In some embodiments, outer layer  306  is a thin, metal foil. In other embodiments, outer layer  306  is a thin sheet that is suitably made of plastic. The use of thinner materials for outer layer  306  may increase the flexibility of heat exchanger  300 , reduce the weight of heat exchanger  300 , and/or permit it to conform to more irregular shaped devices. In general, outer layer  306  may be made of any material of sufficient strength and impermeability to retain a heat transfer fluid within heat exchanger  300 . 
         [0033]      FIG. 4  is a simplified diagram of a closed loop temperature control or regulation system  400  including heat exchanger  300  (heat exchanger may alternatively be referred to as a meshplate). Heat exchanger  300  is coupled to a device  402  that may benefit from temperature regulation provided by heat exchanger. In this embodiment, device  402  is a device, such as PV module  100 , that generates heat and heat exchanger  300  is used to reduce the temperature and/or slow the rise in temperature of device  402 . In other embodiments, heat exchanger  300  may be used to increase the temperature of device  402  and/or slow the decrease in temperature of device. 
         [0034]    In this embodiment, a pump  404  pumps a thermal transfer fluid (e.g., a coolant) to an inlet (not shown in  FIG. 4 ) of heat exchanger  300 . The transfer fluid passes into chamber  305  of fluid layer  304  through the inlet. Within chamber  305 , the thermal transfer fluid draws off heat from device  402 , via thermal conduction through connection of inner layer  302  to device  402 . The thermal transfer fluid exits heat exchanger  300  via an outlet (not shown in  FIG. 4 ) and is directed to a fluid heat exchanger  406 . Fluid heat exchanger  406  may be any heat exchange device suitable for extracting the heat carried by the thermal transfer fluid. For example, fluid heat exchanger may be a radiator, an extended length of thermally conductive conduit, a condenser, etc. Moreover, in some embodiments fluid heat exchanger  406  may be part of another system, such that heat extracted from thermal transfer fluid may be used by the other system. In one example embodiment fluid heat exchanger  406  is a radiator used to warm the air inside a structure. In another embodiment fluid heat exchanger  406  is used to heat water. 
         [0035]    As will be readily understood by those of ordinary skill in the art, system  400  may, additionally or alternatively, be used to heat device  402 . In such embodiments, thermal transfer fluid having a temperature greater than device  402  is pumped by pump  404  to heat exchanger  300 . Within chamber  305 , the thermal transfer fluid loses its heat to device  402 , via conduction through inner layer  302 . Fluid heat exchanger  406  then increases the temperature of the heat transfer fluid before pump  404  returns the fluid to heat exchange device  300 . A single system  400  may be used to selectively heat or cool device  402  through use of a dual purpose fluid heat exchanger  406  or separate, selectable, fluid heat exchangers  406 : one for heating the thermal fluid and another for cooling the thermal fluid. Thus, device  402  may be cooled by system  400  when temperatures are relatively high, and warmed by system  400  when temperatures are relatively cool. 
         [0036]    A controller  408  controls operation of system  400 . More specifically, controller  408  controls operation of system  400  to obtain a desired amount of cooling and/or heating of device  402 . In some embodiments, controller  408  may monitor a temperature of device  402  with a sensor (not shown). Other embodiments do not include controller  408 . In this embodiment, controller  408  is configured to control operation of pump  404 . Controller  408  may operate pump  404  continuously, intermittently, and/or may pulse pump  404  to achieve a desired heating/cooling of device  402 . In some embodiments, controller  408  may additionally, or alternatively, control operation of fluid heat exchanger  406  and/or heat exchanger  300 . In still other embodiments, controller  408  may also control operation of device  402 . For example, controller  408  may be a PV system controller that controls operation of a direct current (DC) to alternating current (AC) power converter extracting power from a PV module device  402 . 
         [0037]    Controller  408  may be any suitable controller, including any suitable analog controller, digital controller, or combination of analog and digital controllers. In some embodiments, controller  408  includes a processor (not shown) that executes instructions for software that may be loaded into a memory device. The processor may be a set of one or more processors or may include multiple processor cores, depending on the particular implementation. Further, the processor may be implemented using one or more heterogeneous processor systems in which a main processor is present with secondary processors on a single chip. In another embodiment, the processor may be a homogeneous processor system containing multiple processors of the same type. In some embodiments, controller  408  includes a memory device (not shown). As used herein, a memory device is any tangible piece of hardware that is capable of storing information either on a temporary basis and/or a permanent basis. The memory device may be, for example, without limitation, a random access memory and/or any other suitable volatile or non-volatile storage device. The memory device may take various forms depending on the particular implementation, and may contain one or more components or devices. For example, the memory device may be a hard drive, a flash memory, a rewritable optical disk, a rewritable magnetic tape, and/or some combination of the above. The media used by memory device also may be removable. For example, without limitation, a removable hard drive may be used for the memory device. 
         [0038]      FIG. 5  is a cross-sectional illustration of an exemplary assembly including heat exchanger  300  attached to PV module  100 . 
         [0039]    In this embodiment, solar panel  102  includes a front glass  500 , solar cells  502  surrounded by an encapsulant  504 , and a back sheet  506 . In this embodiment, the encapsulant  504  comprises ethylene vinyl acetate (EVA). In other embodiments, any other suitable encapsulant may be used. In this embodiment, back sheet  506  is a polyvinyl fluoride (PVF) material. In other embodiments, back sheet  506  may be any other suitable back sheet material or a laminate of materials, including, for example a laminate of PVF surrounding a polyester material. 
         [0040]    Thermal transfer fluid enters heat exchanger  300  via inlet  508  and passes through chamber  305  to outlet  510 . A spacer  512  is contained within chamber  305 . Spacer  512  separates inner and outer layers  302  and  306  and slows the flow of the thermal transfer fluid through chamber  305  to permit the thermal transfer fluid to absorb heat from solar panel  102 . In this embodiment, spacer  512  includes a mesh. More specifically, spacer  512  is a woven mesh. In other embodiments, spacer  512  may include a non-woven mesh, a sponge, spacer strips, capillary tubes, or some combination of the above. In this embodiment, mesh  512  is attached to inner and outer layers  302  and  306  and substantially fills chamber  305 . 
         [0041]    Heat exchanger  300  may be permanently or semi-permanently integrated into PV module  102 , or may be a standalone component that may be removably attached to a device. A standalone heat exchanger  300  may be coupled to device  402  by any suitable means to provide a thermally connection between inner layer  302  and a surface of device  402 . In some embodiments, heat exchanger  300  is connected to device  402  using a thermally conductive adhesive, including for example a double-sided, thermally conductive tape. 
         [0042]      FIG. 6  is a top view of an exemplary assembly  600  including heat exchanger  300  integrated into PV module  100 .  FIG. 7  is a cross sectional view of assembly  600  taken along the line A-A in  FIG. 6 . 
         [0043]    In assembly  600 , heat exchanger  300  is integrally formed with PV module  100  and does not need to be separately adhered to PV module  100 . Moreover, heat exchanger  300  uses backsheet  506  of PV module  100  as inner layer  302 . Spacer strips  602  extend between inner layer  302  (i.e., backsheet  506 ) and outer layer  306  to define cavity  305 . Although not shown in  FIGS. 6 and 7 , cavity  305  also includes spacer  512 . In this embodiment, spacer  512  is a metallic mesh  512  capable of withstanding the heat and pressure of lamination with PV module  100 . In other embodiments, cavity  305  may include any other suitable filler and/or spacer. Outer layer  306  extends around spacer strips  602  to adhere heat exchanger  300  to PV module  100  and facilitate sealing cavity  305 . 
         [0044]      FIG. 8  is a top view of a stand-alone heat exchanger  300  of one embodiment.  FIG. 9  is a cross sectional view of heat exchanger  300  taken along the line B-B in  FIG. 8 . The embodiment of heat exchanger  300  shown in  FIGS. 8 and 9  is not integrally formed with any device and may be attached to any device, such as PV module  100 , by any suitable type of attachment. In this embodiment, two sets of seals  308  are included around spacer  512 . 
         [0045]      FIGS. 10 and 11  show an example heat exchanger  300  in which spacer  512  includes a parallel arrangement of plastic spacers.  FIG. 10  is a top view, and  FIG. 11  is a cross sectional view taken along the line C-C in  FIG. 10 . Heat exchanger  300  shown in  FIGS. 10 and 11  may be integrated into a device or may be a standalone heat exchanger  300 . The gap between adjacent spacers may be any suitable distance that ensures good fluid flow within the system to improve heat transfer and reduce bloating issues. 
         [0046]      FIG. 12  is a partially schematic cross section of a suitable connection assembly  1200  for use at inlet  508  and/or outlet  510  of any embodiment of heat exchanger  300 . Assembly  1200  includes a male component  1202  positioned inside exchanger  300  and extending through outer layer  306 . A female component  1204  is positioned outside of heat exchanger  300  adjacent outer layer  306 . Female component  1204  receives and surrounds the portion of male component  1202  that extends outside of heat exchanger  300 . A portion of outer layer  306  is trapped between female component  1204  and male component  1202 . Tubing  1206 , used to transport thermal transfer fluid to and from heat exchanger  300 , is inserted into female component  1204  to couple tubing  1206  to male component  1202 . Assembly  1200  forms a liquid tight connection to heat exchanger  300 . Thermal transfer fluid (e.g., a suitable coolant) may be transferred, via tubing  1206  and assembly  1200 , from outside of heat exchanger  300  to the interior of heat exchanger  300 , and vice versa. 
         [0047]      FIG. 13  is a partially schematic view of heat exchanger  300  coupled to a device  1300 . The device may be any suitable device that may benefit from temperature regulation provided by heat exchanger  300 . 
         [0048]    The heat exchangers and systems described herein generally provide inexpensive and effective ways to regulate temperature of a device, such as a PV module. Some embodiments of the heat exchangers disclosed herein can be integrated into the backsheet structure of a PV module using only an encapsulant and, thereby, can capitalize on existing manufacturing infrastructure and its economy of scale. Some embodiments of the heat exchangers can be used with a simple attachment mechanism to be affixed to nearly any PV modules, thereby making it field-retrofittable and easy to clean and/or replace. These heat exchangers are thus usable convert a conventional PV system or module into a PV-thermal system. 
         [0049]    Moreover, coolant losses in the exemplary heat exchangers and systems will be negligible in a properly constructed system because coolant is retained within the system, i.e., it is a closed loop system, and there is no provision to allow coolant to intentionally escape. When used to cool PV modules, some heat exchangers of this disclosure have produced a decrease in PV module temperature of 18-20° C., and increased power output of the PV modules by about 10% at peak operating conditions. Other implementations may result in greater or lesser temperature reductions and/or greater or lesser increases in PV module efficiency. 
         [0050]    When introducing elements of the present invention or the embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 
         [0051]    As various changes could be made in the above without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.