Abstract:
A power-generating device includes a thermoelectric material contoured to conform to at least a portion of a tubular and at least two conductors in operable communication with the thermoelectric material.

Description:
BACKGROUND 
       [0001]    Tubular systems often employ tools that require electrical power, such as, motors and solenoids, for example, in the case of a downhole completion application. Some systems employ dynamos to supply the electrical power needed. Dynamos are electrical generators that have rotors turned by mud motors or turbines driven by fluid flow. These devices serve their function adequately. However, with the moving parts operating within extreme environments, such as those found downhole including high pressures, high temperatures, fast moving erosive and caustic fluids littered with contaminants, for example, maintenance of such devices can be difficult, time consuming and labor intensive. Devices that lessen some of the foregoing issues are well received in the art. 
       BRIEF DESCRIPTION 
       [0002]    Disclosed herein is a power-generating device that includes a thermoelectric material contoured to conform to at least a portion of a tubular and at least two conductors in operable communication with the thermoelectric material. 
         [0003]    Further disclosed is a method of making a generating device. The method includes, casting a sheet of thermoelectric material, bonding a layer of conductive material to a first surface of the thermoelectric material, and bonding a layer of conductive material to a second surface of the thermoelectric material thereby constructing a layered assembly. The layered assembly is formed to be perimetrically mountable to a tubular surface. 
         [0004]    Further disclosed is a method of making a generating device. The method includes extruding a thermoelectric material, bonding a layer of conductive material to a first surface of the thermoelectric material, and bonding a layer of conductive material to a second surface of the thermoelectric material. The foregoing layered assembly is formed to be perimetrically mountable to a tubular surface. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
           [0006]      FIG. 1  depicts an end view of a power-generating device disclosed herein; 
           [0007]      FIG. 2  depicts a cross sectioned side view of the power-generating device of  FIG. 1  taken at arrows  2 - 2 ; 
           [0008]      FIG. 3  depicts a partially sectioned perspective view of a portion of a layered assembly employed in the construction of the power-generating device of  FIG. 1 ; 
           [0009]      FIG. 4  depicts a sequential representation of steps employed during an embodiment of a construction process for the power-generating device of  FIG. 1 ; and 
           [0010]      FIG. 5  depicts a partial side view of a downhole completion application employing the power-generating device of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
         [0012]    Referring to  FIGS. 1-3 , an embodiment of a power-generating device is disclosed generally at  10 . The power-generating device  10  works on the principle of the Seebeck effect to convert temperature differences across a thermoelectric material directly into electricity, and uses no moving parts in the process. The power-generating device  10  includes, a layered assembly  14 , conformed to a surface  18  (an outer surface in this embodiment) of a tubular  22 . The layered assembly  14  has a core  26  of thermoelectric material  30 , with conductors  34 ,  38 , shown herein as layers of conductive material, electrically bonded to opposing surfaces  44 ,  48  of the thermoelectric material  30 . A protector  50  including layers  54 ,  58  of electrically insulative material electrically insulates the conductors  34 ,  38  while fluidically isolating the conductors  34 ,  38  and the thermoelectric material  30  from an environment that the power-generating device  10  is submerged within. Terminals  64 ,  68  sealably penetrate the protector  50  and are electrically connected to the conductors  34 ,  38  respectively. The foregoing structure generates electrical energy in the thermoelectric material  30  when a radially oriented temperature gradient exists thereacross. Connection to the terminals  64 ,  68  allow the electrical energy generated to be conducted to a load (not shown) such as, an electrical motor, solenoid, heater or battery, for example. 
         [0013]    Referring to  FIG. 3 , the layered assembly  14  is shown in a flat position with portions of each layer removed for illustrative purposes. The thermoelectric material  30  that constitutes the core  26  can be made of solid composite materials as described in the paper, “Thermoelectric Behavior of Segregated-Network Polymer Nanocomposites,” James C. Grunlan, et al.; Nano Letters, 2008 Vol. 8, No. 12, pgs. 4428-4432, incorporated herein by reference in its entirety. Although this thermoelectric material includes both polymeric particles and carbon nano-particles, alternate thermoelectric materials may be employed as long as they meet the requirements outlined herein. The thermoelectric material  30  can be processed by methods, such as, casting or extruding, for example, to form a sheet of the core  26 . After which, in this embodiment, the conductors  34 ,  38  are electrically and optionally mechanically bonded to the surfaces  44 ,  48  respectively. The conductors can be made of conductive materials, such as, copper, gold, silver or aluminum, for example. These materials can be bonded to the core  26  in one of several ways including, vapor deposition, soldering and brazing, for example. The insulative layers  54 ,  58  are bonded to the conductors  34 ,  38  respectively. The insulative layers  54 ,  48  may be sheets of insulative material such as polymeric, elastomeric or glass, for example. The insulative layers  54 ,  58  can be bonded to the conductors  34 ,  48  through chemical and mechanical means such as bonding with an adhesive agent, for example. Portions  74 ,  78  of the layers  54 ,  58  that extend beyond the core  26  and the conductors  34 ,  38  can be sealably attached to one another through adhesive means compatible with the material that the insulative layers  54 ,  58  are constructed of. In alternate embodiments the insulative layers  54 ,  58  can be applied to the core  26  and the conductors  34 ,  38  by conformal coating processes, such as, by dipping or spraying, for example. 
         [0014]    The terminals  64 ,  68  can be electrically connected to the conductors  34 ,  38  either before or after the insulative layers  54 ,  48  are applied. Processes, such as, soldering, welding and brazing of the terminals  64 ,  68  to the conductors  34 ,  48  may be facilitated by doing so prior to application of the layers  54 ,  58  over the conductors  34 ,  38 . Electrical attachment of the terminals  64 ,  68  to the conductors  34 ,  38  after the layers  54 ,  58  are applied can be done by insulation displacement methods. Regardless of the method of electrical attachment of the terminals  64 ,  68  to the conductors  34 ,  38  sealing of the terminals to the layers  54 ,  58  allows the layers  54 ,  58  to protect the conductors  34 ,  38  and the thermoelectric material  30  from fluids and other environmental conditions within which the layered assembly  14  may be submerged. 
         [0015]    Referring to  FIG. 4 , the layered assembly  14  can be heated above a glass transition temperature of the materials employed and then rolled about a perimeter of a die  82  to a desired shape, such, as a cylinder  86 , for example, as illustrated in this embodiment. After this forming operation, the layered assembly  14  can be cooled, to a temperature below the glass transition temperature, after which the die  82  may be removed therefrom. The formed layered assembly  14  can then be assembled about the tubular  22  and attached thereto by adhesive, clamping, or wrapping with another material, for example. Alternately, the layered assembly  14  can be formed directly onto the outer surface  18  of the tubular  22  thereby employing the tubular  22  as the die  82  in the forming process directly. 
         [0016]    Since, as mentioned above, the thermoelectric material  30  may be extruded, as opposed to being cast, for example, it can be extruded directly into a desired shape, (i.e. the cylinder  86  in the example illustrated). Consequently, the shape of the core  26  of the thermoelectric material  30 , as formed, can strongly influence which methods should be employed to bond the conductors  34 ,  38  and the insulative layers  54 ,  58  thereto. Regardless of the methods of assembly employed, however, the functioning of the finished power-generating device  10  should not be significantly altered. 
         [0017]    Referring to  FIG. 5 , although an embodiment of the power-generating device  10  disclosed herein is shown employed in a downhole completion application, it should be understood that the power-generating device  10  disclosed herein is not limited to such application. For example, the power-generating device  10  could be employed above ground on an oil or gas pipeline that have a temperature gradient thereacross. The downhole application illustrated herein shows two of the power-generating devices  10  positioned longitudinally displaced from one another along the tubular  22 , illustrated herein as a drill or other type of string  90  positioned within a casing  92  in a borehole  93 . The power-generating devices  10  are connected to one another through a connecting module  94  that provides electrical continuity from the terminals  64 ,  68  (not shown in this view) of one of the power-generating devices  10  to the terminals  64 ,  68  of the other of the power-generating devices  10 . Although only two of the power-generating devices  10  are illustrated herein any number of the power-generating devices  10  could be connected in the same fashion. The connecting module  94  can connect two of the power-generating devices  10  along a single length of drill string pipe or can be configured to connect two of the power-generating devices  10  that are located on separate pipes of the string  90 . The connecting module  94 , or similar device, could connect power-generating devices  10  that are nested one radially inside of another. Additionally, the connecting module  94  of a similar device could also connect between one of the power-generating devices  10  and a tool  98 , such as, an actuator, heater, motor, sensors, batteries or monitoring circuitry, for example, as illustrated. Since the surface area available along the string  90  for mounting a plurality of the power-generating devices  10  can be very large and the temperature differential across the power-generating devices  10  due to production fluids flowing therethrough can be significant the electrical energy generation potential is great. As such, the power-generating devices  10  disclosed herein can provide power to the tool  98  without having to be connected to surface nor having to generate the power downhole with movable componentry such as mud motors and turbines, for example. 
         [0018]    While the invention has been described with reference to an exemplary embodiment or 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 invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.