Abstract:
A thermophotovoltaic electricity generating system having a heat source generating a thermal emission having a plurality of wavelengths. There is an optical filter filtering the thermal emission into a filtered emission. There is also a thermophotovoltaic device receiving the filtered emission. The thermophotovoltaic device is configured to absorb the thermal emission converting the thermal emission into electricity.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present disclosure is related to electrical generation systems. More particularly, the present disclosure is related to thermophotovoltaic (TPV) electrical generation systems. 
         [0003]    2. Description of Related Art 
         [0004]    Many vehicles require a primary mover and an electrical generating system. A typical electrical generating system, such as an alternator or generator, has the disadvantage of being a parasitic system wherein the electrical generation system utilizes the primary mover in operation. Consequently, the electrical generation system is a power drain on the primary mover, resulting in an inefficient system. 
         [0005]    Due to environmental concerns and the rising costs of fuel, there is an intrinsic desire to operate vehicles as efficiently as possible. Thus, there is a need for an electrical generating system that is non-parasitic. Even better, there is a need for an electrical generating system that can utilize by-products from the primary mover in operation. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    It is an object of the present invention to provide thermophotovoltaic electricity generating systems. 
         [0007]    These and other objects and advantages of the present invention are provided by a thermophotovoltaic electricity generating system having a heat source generating a thermal emission having a plurality of wavelengths. There is an optical filter filtering the thermal emission into a filtered emission. There is also a thermophotovoltaic device receiving the filtered emission. The thermophotovoltaic device is configured to absorb the thermal emission converting the thermal emission into electricity. 
         [0008]    A method for generating electricity is also provided. The method includes filtering a thermal emission to generate a filtered emission, directing the filtered emission to a thermophotovoltaic device, and operating the thermophotovoltaic device so that the filtered emission is converted into electricity. 
         [0009]    The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0010]      FIG. 1  is an exemplary embodiment of a TPV electrical generation system according to the present disclosure. 
           [0011]      FIG. 2  is an exemplary embodiment of a TPV electrical generation system according to the present disclosure further comprising an optical concentrator. 
           [0012]      FIG. 3  is an exemplary embodiment of a method of generating electricity according to the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    Referring to the drawings and in particular to  FIG. 1 , an exemplary embodiment of a thermophotovoltaic (TPV) electrical generation system  10  according to the present disclosure is shown. Advantageously, system  10  converts radiant heat energy into electricity and since system  10  has few moving parts, the system is relatively quiet and requires low maintenance. 
         [0014]    System  10  includes a heat source  12 , an optical filter  16 , and a themmophotovoltaic device  20 . 
         [0015]    Thermophotovoltaic (TPV) device  20  can be any device capable of generating electricity from the heat radiated from heat source  12 . For example, TPV device  20  can be a photovoltaic diode cell that generates electricity when exposed to radiant heat of one or more particular wavelengths. In this manner, the photovoltaic diode absorbs radiation of the one or more particular wavelengths and converts the radiated photons into electricity. 
         [0016]    For purposes of discussion, heat source  12  is described herein as a jet engine of a vehicle such as an airplane (not shown). However, it is contemplated by the present disclosure for system  10  to find use in various applications in a wide-array of industries, including nuclear operations, coal operations, internal combustion engines, waste heat from petrochemical, cement, agro and other industrial sources and with a wide array of heat sources  12 . 
         [0017]    In use, heat source  12  generates a thermal emission  14 . Thermal emission  14  comprises radiant heat emissions having a plurality of varying wavelengths. Thus, it has been determined by the present disclosure that much of the energy within thermal emission  14  is simply not useable by TPV device  20  for generating electricity. Further, it has also been determined by the present disclosure that, in some instances, the plurality of wavelengths of thermal emission  14  can interfere with the particular wavelength or wavelengths that is/are useable by TPV device  20 . 
         [0018]    Accordingly, system  10  includes optical filter  16  positioned between heat source  12  and TPV device  20  so that thermal emission  14  flows through the optical filter to form filtered emission  18 . 
         [0019]    Advantageously, optical filter  16  is selected so that most, and preferably all, of the wavelengths of thermal emission  14  that interfere with the operation of TPV device  20  have been removed from filtered emission  18 . Further, optical filter  16  is, in some embodiments, selected so that the resultant filtered emission is matched to the useable wavelength or wavelengths of TPV device  20 . 
         [0020]    In some embodiments, optical filter  16  is a type of photonic crystal that can convert a broad wavelength of thermal emission  14  into one or a plurality of sharp wavelengths of filtered emission  18 . It is contemplated by the present disclosure that optical filter  16  can be composed of any known type of material suitable for filtering thermal emission  14 , including but not limited to, bulk crystals, quantum dots, and nanoparticles comprised of typical semiconductor materials such as silicon, germanium, and gallium arsenide. It is also contemplated herein that optical filter  16  can comprise mixed metal oxides, including but not limited to, titanium dioxide, zirconium oxide, cerium oxide, or combinations thereof. The filtering capacity of optical filter  16  may be generated utilizing structural and morphological changes. 
         [0021]    TPV device  20  absorbs and converts filtered emission  18  into electricity  22  in a known manner. Accordingly, system  10 , due to the incorporation of optical filter  16  in the energy path between heat source  12  and TPV device  20  ensures that the TPV device is exposed to filtered emission  18 , which minimizes wavelengths that negatively effect the performance of the TPV device while maximizing the wavelength and/or wavelengths that are useable by the TPV device for the generation of electricity  22 . As such, system  10  maximizes the efficiency of TPV device  20 . 
         [0022]    Referring now to  FIG. 2 , system  10  is shown having an optical concentrator  24  between optical filter  16  and TPV device  20  so that filtered emission  18  leaving the optical filter  16  passes through the optical concentrator. Optical concentrator  24  enhances the intensity of filtered emission  18  impinging on TPV device  20  so as to enhance the amount of electrons that are generated and collected. As filtered emission  18  passes through optical filter  16 , it is concentrated into a concentrated thermal emission  26  and directed to TPV device  20 . Concentrated thermal emission  26  is then absorbed by TPV device  20  and converted into electricity  22 . 
         [0023]    In  FIG. 2 , optical concentrator  24  is positioned after optical filter  16  and before TPV device  20 . It should be recognized, however, that optical concentrator  24  may be placed anywhere in the path of energy radiating from heat source  12 . 
         [0024]    Additionally, optical concentrator  24  is shown in  FIG. 2  as a separate component of system  10 . However, it is also contemplated for optical concentrator  24  to be integral with optical filter  16 . For example, optical filter  16  can be coated so as to form optical concentrator  24  on the optical filter. 
         [0025]    Advantageously, system  10  may be used for low temperature heat sources, e.g. sources emitting thermal emission  14  at temperatures of less than 500 degrees Celsius, because none of the materials will undergo significant degradation. It is contemplated herein that system  10  may be used in conjunction with industrial waste heat, stationary or mobile internal combustion engines, and stationary or mobile turbine engines. 
         [0026]    Referring now to  FIG. 3 , an exemplary embodiment of a method according to the present disclosure of generating electricity is generally illustrated as reference numeral  50 . Advantageously, method  50  converts thermal emissions  14  from heat source  12  into electricity  22 . 
         [0027]    Method  50  includes an operating step  52 , a filtering step  54 , a directing step  58 , and a controlling step  60 . During operating step  52 , heat source  12  is running and generating thermal emission  14 . Thermal emission  14  then passes through optical filter  16  in filtering step  54  and thermal emission  14  is converted into filtered emission  18 . During directing step  58 , filtered emission  18  exiting optical filter  16  is directed onto TPV device  20 . During controlling step  60 , TPV device  20  is optionally turned either on or off such that the TPV device  20  can selectively convert filtered emission  18  into electricity as desired. 
         [0028]    It is also contemplated herein, that method  50  may include concentrating step  56 . As discussed above with respect to  FIG. 2 , concentrating step  56  may occur before, during, or after filtering step  54 . During concentrating step  56 , optical concentrator  24  generates concentrated emission  26  and directs the concentrated emission towards TPV device  20 . 
         [0029]    It should also be noted that the terms “first”, “second”, “third”, “upper”, “lower”, and the like may be used herein to modify various elements. These modifiers do not imply a spatial, sequential, or hierarchical order to the modified elements unless specifically stated. 
         [0030]    While the present disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated, but that the disclosure will include all embodiments falling within the scope of the appended claims.