This disclosure generally relates to temperature regulation, and more specifically, to methods and systems for regulating temperature using a multilayered heat exchanger.
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/m2 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.
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.
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.
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.
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.
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.
Like reference symbols in the various drawings indicate like elements.
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.
Referring initially to
Solar panel 102 includes a top surface 106 and a bottom surface 108 (shown in
As shown in
As shown in
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.
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.
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.
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.
In this embodiment, a pump 404 pumps a thermal transfer fluid (e.g., a coolant) to an inlet (not shown in
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.
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.
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.
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.
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.
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.
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
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.
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.
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.
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.
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.
Number | Date | Country | |
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61737582 | Dec 2012 | US | |
61759109 | Jan 2013 | US |