Patent Application
20110017875
The present disclosure is directed to a concentrated photovoltaic array, and more specifically to such an array providing power to a satellite.
Photovoltaic arrays (also known as Solar Power Generators) are often used where typical stored energy solutions, such as batteries, are unacceptable, and where a device needing power will have access to a steady source of light. As an example, a terrestrial solar power farm utilizes photovoltaic arrays to generate power for supplying power to the power grid. The atmosphere surrounding the arrays typically provides adequate heat convection to remove excess heat and prevent overheating, such that thermal management is not an issue.
An exemplary reflective concentrated photovoltaic array includes a support structure with multiple primary reflectors connected to it. The primary reflectors extend outward from the center structure, and reflect light onto a concentrated photo voltaic array. The concentrated photovoltaic array is connected to the center structure via a heat pipe radiator.
An exemplary embodiment includes a satellite with at least one of the above described concentrated photovoltaic arrays connected to a main body. The concentrated photovoltaic array is used to generate power for the satellite's operations, and uses the described heat pipe radiator to remove heat from the solar panels.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
While the satellite 100 is folded for transport, the primary reflectors 202 are substantially parallel to and adjacent to the heat pipe radiator 206. Once the satellite 100 is deployed, the primary reflectors 202 rotate away from the heat pipe radiator 206 to a desired angle. The desired angle can be any angle which allows the primary reflector 202 to direct reflected light onto the concentrated photovoltaic array 208. By way of example, the primary reflectors 202 can be at a 90° angle relative to the heat pipe radiator 206. When light reflects off of the primary reflectors 202 and onto the concentrated photovoltaic array 208, the light is converted into electrical energy using known photovoltaic energy generation techniques. The energy can then be used to power the satellite 100. The photovoltaic technique produces excess heat as a byproduct of power generation.
The excess heat rejects from the front and the back of the photovoltaic array 208. In terrestrial applications, the surrounding atmosphere absorbs the heat via heat convection, thereby preventing or limiting any overheating. The rate at which the waste heat can be rejected from the concentrated photovoltaic array in any environment is related to the exposed surface area contacting a fluid, into which the excess heat is transferred. In a terrestrial embodiment the fluid would typically be air. Environmental conditions can prevent the excess heat from being adequately rejected away from the CPV. By way of example, a lack of an atmosphere, such as in space, will reduce the rate at which the excess heat can be radiated off of the exposed surface area.
To remove heat, the solar panel array 100, 200 or 300 may include a heat pipe radiator 206. The heat pipe radiator 206 includes heat pipes 220 which connect the concentrated photovoltaic array 208 to the support structure 104. The heat pipe radiator also includes radiating fins 230 mounted on two sides of heat pipes 220, which provide structure continuation and heat radiation surface areas. The radiating fins illustrated in
A heat pipe 220 is a sealed pipe or tube made of a material with high thermal conductivity, such as copper or aluminum. All air is removed from the empty heat pipe and the pipe is partially filled with a working fluid, (or coolant), chosen to match the operating temperature. Some example fluids are water, ethanol, acetone, sodium, or mercury. The partial vacuum inside the tube is near or below the vapor pressure of the fluid, and consequently a portion of the fluid will be in the liquid phase and another portion will be in the gas phase. The heat pipe 220 transfers the heat from a hot end, connected to the concentrated photovoltaic array 208 through a thermally conductive connection, by heating up the liquid portion of the coolant resulting in phase change to gas phase. The heated gas then condenses at the cold end of the heat pipe, releasing the heat into radiator surface areas, which then release the heat into the surrounding environment. The condensed coolant can be transported back to the hot end through wicks inside the heat pipe via capillary force.
The primary reflector 202 is a flat surface Fresnel reflector. It is made of plurality of Fresnel grooves and each groove has a specific slope of inclination. When shining by solar rays it concentrates incoming solar rays to the concentrated photovoltaic array 208 or to the secondary reflector 414.
While the above examples are directed toward applications in space, the disclosed concepts may provide significant benefits in any environment where more rapid heat radiation is desired.
Although two examples of this invention have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
