Patent Publication Number: US-2021167269-A1

Title: Power generating apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0159249, filed on Dec. 3, 2019, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates to a power generating apparatus, and more specifically, to a power generating apparatus which generates electricity using a temperature difference between a low temperature portion and a high temperature portion of a thermoelectric device. 
     2. Discussion of Related Art 
     A thermoelectric effect is a phenomenon occurring due to the movement of electrons and holes in a material and means direct energy conversion between heat and electricity. 
     A thermoelectric device is a generic term of devices in which the thermoelectric effect is used and has a structure in which a P-type thermoelectric material and an N-type thermoelectric material are disposed between and bonded to metal electrodes to form a PN junction pair. 
     Thermoelectric devices may be divided into devices which use a change in electrical resistance according to a change in temperature, devices which use the Seebeck effect in which an electromotive force is generated due to a temperature difference, and devices which use the Peltier effect in which heating or heat absorption occurs due to current. 
     The thermoelectric devices have been variously applied to home appliances, electronic components, communication components, and the like. For example, the thermoelectric devices may be applied to cooling apparatuses, heating apparatuses, power generating apparatuses, and the like. Therefore, the demand for thermoelectric performance of the thermoelectric devices is gradually increasing. 
     Recently, there are needs to generate electricity using high temperate waste heat generated from engines of vehicles, vessels, and the like and thermoelectric devices. In this case, a duct through which a first fluid passes may be disposed at a side of a low temperature portion of the thermoelectric device, a radiation fin may be disposed at a side of a high temperature portion of the thermoelectric device, and a second fluid may pass through the radiation fin. Accordingly, electricity may be generated due to a temperature difference between the low temperature portion and the high temperature portion of the thermoelectric device, and electricity generation performance may depend on a structure of a power generating apparatus. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to providing a power generating apparatus which generates electricity using a temperature difference between a low temperature portion and a high temperature portion of a thermoelectric device. 
     According to an aspect of the present invention, there is provided a power generating apparatus including a duct through which a first fluid passes, a first thermoelectric module and a second thermoelectric module disposed on a first surface of the duct to be spaced apart from each other, a connector disposed between the first thermoelectric module and the second thermoelectric module on the first surface of the duct, and a shield member disposed on the connector on the first surface of the duct, wherein the shield member includes a first face and a second face having a height higher than a height of the first face. 
     Each of the first thermoelectric module and the second thermoelectric module may include a thermoelectric device disposed on the first surface and a radiation fin disposed on the thermoelectric device, and an upper surface of the first face may be disposed at a height lower than or equal to a height of a lower surface of the radiation fin. 
     An electrical wire drawn out from at least one of the thermoelectric device of the first thermoelectric module and the thermoelectric device of the second thermoelectric module may be connected to the connector, and a lower surface of the second face may be disposed at a height higher than a height of the electrical wire and a height of the connector. 
     The shield member may further include a third face disposed between the first face and the second face and having a height higher than the height of the first face and lower than the height of the second face. 
     The third face may be disposed at the height higher than the height of the electrical wire, and the second face may be disposed at the height higher than the height of the connector. 
     The shield member may further include a first connecting face connecting the upper surface of the first face and an upper surface of the third face and a second connecting face connecting the upper surface of the third face and an upper surface of the second face, and the first connecting face may be inclined at an angle greater than 0° and less than 90° with respect to the upper surface of the first face. 
     The first face of the shield member may be symmetrically disposed between the first thermoelectric module and the second thermoelectric module. 
     An area of the third face may be greater than an area of the second face. 
     The shield member may include a plurality of second faces which are identical to the second face and spaced apart from each other. 
     The third face may be disposed between two second faces spaced apart from each other, and the second connecting face may be symmetrically disposed to connect the upper surface of the second face and the upper surface of the third face. 
     The power generating apparatus may further include an insulating member disposed between the first surface and a lower surface of the shield member. 
     The insulating member may be disposed on side surfaces of the electrical wire and the connector on the first surface. 
     The insulating member may not be disposed on at least a portion between the electrical wire and the lower surface of the shield member and between the connector and the lower surface of the shield member. 
     An upper surface of the second face may be disposed to have a maximum height, which is 0.25 times a height difference between the lower surface of the radiation fin and an upper surface of the radiation fin, from the lower surface of the radiation fin. 
     A temperature of a second fluid sequentially passing through the radiation fin of the first thermoelectric module, an upper surface of the shield member, and the radiation fin of the second thermoelectric module may be different from a temperature of the first fluid. 
     A flow direction of the first fluid may be different from a flow direction of the second fluid. 
     The flow direction of the first fluid may be perpendicular to the flow direction of the second fluid. 
     The duct may include a first duct and a second duct adjacent to the first duct, and the shield member may be disposed between the first thermoelectric module disposed on the first surface of the first duct and the first thermoelectric module disposed on the first surface of the second duct. 
     According to another aspect of the present invention, there is provided a power generating apparatus including a duct through which a first fluid passes, a first thermoelectric module and a second thermoelectric module disposed on a first surface of the duct to be spaced apart from each other, a first connector disposed between the first thermoelectric module and the second thermoelectric module on the first surface of the duct, a first shield member disposed on the first connector on the first surface of the duct, a third thermoelectric module and a fourth thermoelectric module disposed on a second surface facing the first surface of the duct to be spaced apart from each other, a second connector disposed between the third thermoelectric module and the fourth thermoelectric module on the second surface of the duct, and a second shield member disposed on the second connector on the second surface of the duct, wherein each of the first shield member and the second shield member includes a first face and a second face having a height higher than a height of the first face. 
     Each of the first to fourth thermoelectric modules may include a thermoelectric device disposed on the corresponding surface of the duct and a radiation fin disposed on the thermoelectric device, and a distance between the surface of the duct and the first face may be less than or equal to a minimum distance between the surface of the duct and the radiation fin. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing exemplary embodiments thereof in detail with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view illustrating a power generating apparatus according to one embodiment of the present invention; 
         FIG. 2  is one cross-sectional view illustrating the power generating apparatus of  FIG. 1 ; 
         FIG. 3  is another cross-sectional view illustrating the power generating apparatus of  FIG. 1 ; 
         FIG. 4  is an exploded perspective view illustrating the power generating apparatus of  FIG. 1 ; 
         FIG. 5  is a partially enlarged view illustrating the power generating apparatus of  FIG. 1 ; 
         FIG. 6  is a cross-sectional view illustrating a thermoelectric device; 
         FIG. 7  is a perspective view illustrating the thermoelectric device; 
         FIG. 8  is a partial perspective view illustrating the power generating apparatus including a shield member according to one embodiment of the present invention; 
         FIG. 9  is a cross-sectional view illustrating the power generating apparatus of  FIG. 8 ; 
         FIG. 10  is an enlarged view illustrating a vicinity of the shield member of the power generating apparatus of  FIG. 8 ; 
         FIG. 11  is a perspective view illustrating the shield member according to one embodiment of the present invention; 
         FIG. 12  is a cross-sectional view illustrating the shield member according to one embodiment of the present invention; 
         FIGS. 13A and 13B  are a set of a top view and a cross-sectional view illustrating a shield member according to a comparative example; 
         FIG. 14  is a view illustrating a height difference between the shield member and a radiation fin according to the comparative example of  FIG. 13 ; 
         FIGS. 15A to 15C  are views illustrating a flow of a gas passing through the shield member according to the comparative example; 
         FIGS. 16A and 16B  are a set of a top view and a cross-sectional view illustrating the shield member according to the embodiment of the present invention; 
         FIG. 17  is a view illustrating a height difference between the shield member and a radiation fin according to the embodiment of  FIG. 16 ; and 
         FIGS. 18A to 18C  are views illustrating a flow of a fluid passing through the shield member according to the embodiment of  FIG. 16 . 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings. 
     However, the technical spirit of the present invention is not limited to some embodiments which will be described and may be realized using various other embodiments, and at least one component of the embodiments may be selectively coupled, substituted, and used to realize the technical spirit within the range of the technical spirit. 
     In addition, unless clearly and specifically defined otherwise by context, all terms (including technical and scientific terms) used herein can be interpreted as having customary meanings to those skilled in the art, and meanings of generally used terms, such as those defined in commonly used dictionaries, will be interpreted in consideration of contextual meanings of the related technology. 
     In addition, the terms used in the embodiments of the present invention are considered in a descriptive sense and not to limit the present invention. 
     In the present specification, unless clearly indicated otherwise by the context, singular forms include the plural forms thereof, and in a case in which “at least one (or one or more) among A, B, and C” is described, this may include one or more of all combinations which can be combined with A, B, and C. 
     In descriptions of the components of the present invention, terms such as “first,” “second,” “A,” “B,” “a,” and “b” can be used. 
     The terms are only to distinguish one element from another element, and an essence, order, and the like of the element are not limited by the terms. 
     It should be understood that, when an element is referred to as being “connected or coupled” to another element, such a description may include both a case in which the element is directly connected or coupled to another element, and a case in which the element is connected or coupled to another element with still another element disposed therebetween. 
     In a case in which any one element is described as being formed or disposed “on or under” another element, such a description includes both a case in which the two elements are formed or disposed to be in direct contact with each other and a case in which one or more other elements are disposed between the two elements. In addition, when one element is described as being formed “on or under” another element, such a description may include a case in which the one element is formed at an upper side or a lower side with respect to another element. 
       FIG. 1  is a perspective view illustrating a power generating apparatus according to one embodiment of the present invention,  FIG. 2  is one cross-sectional view illustrating the power generating apparatus of  FIG. 1 ,  FIG. 3  is another cross-sectional view illustrating the power generating apparatus of  FIG. 1 ,  FIG. 4  is an exploded perspective view illustrating the power generating apparatus of  FIG. 1 , and  FIG. 5  is a partially enlarged view illustrating the power generating apparatus of  FIG. 1 . 
     Referring to  FIGS. 1 to 4 , a power generating apparatus  1000  includes a duct  1100 , a first thermoelectric module  1200 , a second thermoelectric module  1300 , and a gas guide member  1400 . A plurality of power generating apparatuses  1000  may be disposed in parallel at predetermined intervals to form an electricity generation system. Although not illustrated in the drawings, a second fluid may pass between two power generating apparatuses  1000  disposed to be spaced apart from each other at the predetermined interval. For example, the second thermoelectric module  1300  of one power generating apparatus  1000  and the first thermoelectric module  1200  of another adjacent power generating apparatus  1000  are disposed in parallel to be spaced apart from each other at the predetermined interval, and the second fluid may pass therebetween. 
     The power generating apparatus  1000  according to the embodiment of the present invention may generate electricity using a temperature difference between a first fluid flowing in the duct  1100  and the second fluid passing outside the duct  1100 . In the present specification, a temperature of the first fluid flowing in the duct  1100  may be lower than a temperature of the second fluid passing radiation fins of the thermoelectric modules  1200  and  1300  disposed outside the duct  1100 . In the present specification, the first fluid may also be referred as a cooling fluid, and the second fluid may also be referred as a gas or high temperature fluid. 
     To this end, the first thermoelectric module  1200  may be disposed on one surface of the duct  1100  and the second thermoelectric module  1300  may be disposed on the other surface of the duct  1100 . In this case, among both surfaces of each of the first thermoelectric module  1200  and the second thermoelectric module  1300 , a surface facing the duct  1100  may become a low temperature portion thereof, and power may be generated using a temperature difference between the low temperature portion and a high temperature portion. 
     The first fluid introduced into the duct  1100  may be water but is not limited thereto and may be one of various fluids having cooling performance. A temperature of the first fluid introduced into the duct  1100  may be less than 100° C., preferably less than 50° C., and more preferably less than 40° C., but is not limited thereto. A temperature of the first fluid passing through and discharged from the duct  1100  may be higher than a temperature of the first fluid introduced into the duct  1100 . The duct  1100  includes a first surface  1110 , a second surface  1120  disposed to face the first surface  1110  in parallel, a third surface  1130  disposed between the first surface  1110  and the second surface  1120 , and a fourth surface  1140  disposed between the first surface  1110  and the second surface  1120  and facing the third surface  1130 , and the first fluid passes through the duct formed by the first surface  1110 , the second surface  1120 , the third surface  1130 , and the fourth surface  1140 . The first fluid is introduced through a first fluid inlet of the duct  1100  and discharged through a first fluid outlet thereof. An inlet flange (not shown) and an outlet flange (not shown) may be further respectively disposed at a side of the first fluid inlet of the duct  1100  and a side of the first fluid outlet thereof to facilitate introduction and discharge of the first fluid and support the duct  1100 . Alternatively, a plurality of first fluid inlets  1152  may be formed in a fifth surface  1150  which is one surface of two surfaces between the first surface  1110 , the second surface  1120 , the third surface  1130 , and the fourth surface  1140  of the duct  1100  and a plurality of first fluid outlets  1162  may be formed in a sixth surface  1160  which is the other surface of two surfaces between the first surface  1110 , the second surface  1120 , the third surface  1130 , and the fourth surface  1140  thereof. The plurality of first fluid inlets  1152  and the plurality of first fluid outlets  1162  may be connected to a plurality of first fluid passing pipes  1170  in the duct  1100 . Accordingly, the first fluid introduced through the first fluid inlets  1152  may pass through the first fluid passing pipes  1170  and be discharged through the first fluid outlets  1162 . In this case, since the first fluid may be uniformly dispersed in the duct  1100  even when a flow rate of the first fluid is not sufficient to fully fill the duct  1100 , or a surface area of the duct  1100  is large, uniform thermoelectric conversion efficiency may be obtained over the entire surface of the duct  1100 , and the inlet flange and the outlet flange may be omitted. 
     In this case, the first fluid inlets  1152  may be connected to first fluid inlet pipes  1182  through first fitting members  1180 , and the first fluid outlets  1162  may be connected to first fluid outlet pipes  1192  through second fitting members  1190 . 
     In this case, the first fluid inlet pipes  1182  and the first fluid outlet pipes  1192  may be disposed to protrude from the fifth surface  1150  and the sixth surface  1160  of the duct  1100 . 
     Although not illustrated in the drawings, radiation fins may be disposed on an inner wall of the duct  1100 . The number, a shape, and an area, which occupies the inner wall of the duct  1100 , of radiation fins may be variously changed according to a temperature of the first fluid, a temperature of waste heat, a required electricity generation capacity, and the like. For example, an area of the radiation fins occupying the inner wall of the duct  1100  may be in the range of 1 to 40% of a cross sectional area of the duct  1100 . Accordingly, high thermoelectric conversion efficiency can be obtained even without interfering with a flow of the first fluid. In this case, the radiation fins may have a shape which does not interfere with the flow of the first fluid. For example, the radiation fins may be formed in a direction in which the first fluid flows. That is, the radiation fin may have a plate shape extending from the first fluid inlet in a direction toward the first fluid outlet, and the plurality of radiation fins may be disposed to be spaced apart from each other at predetermined intervals. The radiation fins may be integrally formed with the inner wall of the duct  1100 . 
     According to the embodiment of the present invention, the duct  1100  may be provided as a plurality of ducts  1100 . For example, the ducts  1100  may include a first duct  1100 - 1  and a second duct  1100 - 2  adjacent to the first duct  1100 - 1 . Accordingly, since the first fluid may be uniformly dispersed in the first duct  1100 - 1  and the second duct  1100 - 2  even when a flow rate of the first fluid is not sufficient to fully fill the ducts  1100 , uniform thermoelectric conversion efficiency can be obtained over the entire surface of the ducts  1100 . 
     Meanwhile, the first thermoelectric module  1200  is disposed on the first surface  1110  of the duct  1100 , the second thermoelectric module  1300  is disposed on the second surface  1120  of the duct  1100 , and the first thermoelectric module  1200  and the second thermoelectric module  1300  are symmetrically disposed. 
     The first thermoelectric module  1200  and the second thermoelectric module  1300  may be coupled to the duct  1100  using screws. Accordingly, the first thermoelectric module  1200  and the second thermoelectric module  1300  may be stably coupled to the surfaces of the duct  1100 . Alternatively, at least one of the first thermoelectric module  1200  and the second thermoelectric module  1300  may also be bonded to the surface of the duct  1100  using a thermal interface material (TIM)  1212  or  1312 . 
     Meanwhile, the first thermoelectric module  1200  and the second thermoelectric module  1300  respectively include thermoelectric devices  1210  and  1310  disposed on the first surface  1110  and the second surface  1120  and radiation fins  1220  and  1320  disposed on the thermoelectric devices  1210  and  1310 . In this case, a distance between the first surface  1110  and the first radiation fin  1220  may be greater than a distance between the first surface  1110  and the thermoelectric device  1210 , and a distance between the second surface  1120  and the second radiation fin  1320  may be greater than a distance between the second surface  1120  and the thermoelectric device  1310 . As described above, the duct  1100  in which the first fluid flows is disposed on one surface of both surfaces of each of the thermoelectric devices  1210  and  1310 , the radiation fins  1220  and  1320  are disposed on the other surface of each thereof, and when the second fluid passes through the radiation fins  1220  and  1320 , a temperature difference between heat absorbing surfaces and radiation surfaces of the thermoelectric devices  1210  and  1310  may be increased and thus thermoelectric conversion efficiency may be improved. In this case, the direction in which the first fluid flows and a direction in which the second fluid flows may be different. For example, the direction in which the first fluid flows is substantially perpendicular to the direction in which the second fluid flows. 
     In this case, referring to  FIG. 5 , the radiation fins  1220  and  1320  and the thermoelectric devices  1210  and  1310  may be coupled by a plurality of coupling members  1230  and  1330 . To this end, through holes S, through which the coupling members  1230  and  1330  pass, may be formed in at least some of the radiation fins  1220  and  1320  and the thermoelectric devices  1210  and  1310 . In this case, separate insulators  1240  and  1340  may be further disposed between the through holes S and the coupling members  1230  and  1330 . The separate insulators  1240  and  1340  may be insulators surrounding outer circumferential surfaces of the coupling members  1230  and  1330  or insulators surrounding inner walls of the through holes S. Accordingly, insulation distances of the thermoelectric modules can be increased. 
     In this case, a structure of each of the thermoelectric devices  1210  and  1310  may have a structure of a thermoelectric device  100  illustrated in  FIGS. 6 and 7 . Referring to  FIGS. 6 and 7 , the thermoelectric device  100  includes a lower substrate  110 , lower electrodes  120 , P-type thermoelectric legs  130 , N-type thermoelectric legs  140 , upper electrodes  150 , and an upper substrate  160 . 
     The lower electrodes  120  are disposed between the lower substrate  110  and lower surfaces of the P-type thermoelectric legs  130  and the N-type thermoelectric legs  140 , and the upper electrodes  150  are disposed between the upper substrate  160  and upper surfaces of the P-type thermoelectric legs  130  and the N-type thermoelectric legs  140 . Accordingly, the plurality of P-type thermoelectric legs  130  and the plurality of N-type thermoelectric legs  140  are electrically connected through the lower electrodes  120  and the upper electrodes  150 . A pair of the P-type thermoelectric leg  130  and the N-type thermoelectric leg  140  disposed between the lower electrodes  120  and the upper electrode  150  and electrically connected to each other may form a unit cell. 
     For example, when a voltage is applied to the lower electrodes  120  and the upper electrodes  150  through lead wires  181  and  182 , the substrate, through which a current flows from the P-type thermoelectric leg  130  to the N-type thermoelectric leg  140 , may absorb heat to serve as a cooling portion due to the Peltier effect, and the substrate, through which a current flows from the N-type thermoelectric leg  140  to the P-type thermoelectric leg  130 , may be heated to serve as a heating portion due to the Peltier effect. Alternatively, when a temperature difference is applied between the lower electrodes  120  and the upper electrodes  150 , electric charges in the P-type thermoelectric leg  130  and the N-type thermoelectric leg  140  move to generate electricity due to the Seebeck effect. 
     In this case, the P-type thermoelectric leg  130  and the N-type thermoelectric leg  140  may be bismuth-telluride (Bi—Te)-based thermoelectric legs mainly containing Bi and Te. The P-type thermoelectric leg  130  may be a Bi—Te-based thermoelectric leg containing at least one among antimony (Sb), nickel (Ni), aluminum (Al), copper (Cu), silver (Ag), lead (Pb), boron (B), gallium (Ga), Te, Bi, and indium (In). For example, the P-type thermoelectric leg  130  may contain Bi—Sb—Te at 99 to 99.999 wt % which is a main material and at least one at 0.001 to 1 wt % among Ni, Al, Cu, Ag, Pb, B, Ga, and In with respect to a total weight of 100 wt %. The N-type thermoelectric leg  140  may be a Bi—Te-based thermoelectric leg containing at least one among Se, Ni, Al, Cu, Ag, Pb, B, Ga, Te, Bi, and In. For example, the N-type thermoelectric leg  140  may include Bi—Se—Te at 99 to 99.999 wt % which is the main material and at least one at 0.001 to 1 wt % among Ni, Al, Cu, Ag, Pb, B, Ga, and In with respect to a total weight of 100 wt %. Accordingly, in the present specification, the thermoelectric leg may also be referred to as a semiconductor structure, a semiconductor device, a semiconductor material layer, a conductive semiconductor structure, a thermoelectric structure, a thermoelectric material layer, and the like. 
     The P-type thermoelectric leg  130  and the N-type thermoelectric leg  140  may be formed as bulk type or stack type thermoelectric legs. Generally, the bulk type P-type thermoelectric leg  130  or bulk type N-type thermoelectric leg  140  may be formed through a process in which a thermoelectric material is heat-treated to manufacture an ingot, the ingot is grinded and screened to obtain a powder for a thermoelectric leg, the powder is sintered, and a sintered pellet is cut. In this case, the P-type thermoelectric leg  130  and the N-type thermoelectric leg  140  may be polycrystalline thermoelectric legs. When the powder for the thermoelectric leg is sintered to form the polycrystalline thermoelectric leg, the powder may be compressed by a pressure ranging from 100 MPa to 200 MPa. For example, when the sintering is performed for the P-type thermoelectric leg  130 , the powder for the thermoelectric leg may be sintered at 100 to 150 MPa, preferably at 110 to 140 MPa, and more preferably at 120 to 130 MPa. In addition, when the powder for the N-type thermoelectric leg  140  is sintered, the powder for the thermoelectric leg may be sintered at 150 to 200 MPa, preferably at 160 to 195 MPa, and more preferably at 70 to 190 MPa. As described above, in the case in which the P-type thermoelectric leg  130  and the N-type thermoelectric leg  140  are the polycrystalline thermoelectric legs, strengths of the P-type thermoelectric leg  130  and the N-type thermoelectric leg  140  may be increased. The stack type P-type thermoelectric leg  130  or stack type N-type thermoelectric leg  140  may be formed in a process of coating a sheet-shaped base with a paste including a thermoelectric material to form unit members and a process of stacking and cutting the unit members. 
     In this case, the pair of the P-type thermoelectric leg  130  and the N-type thermoelectric leg  140  may have the same shape and volume or may have different shapes and volumes. For example, since electrical conduction properties of the P-type thermoelectric leg  130  and the N-type thermoelectric leg  140  are different, a height or cross sectional area of the N-type thermoelectric leg  140  may be different from that of the P-type thermoelectric leg  130 . 
     In this case, the P-type thermoelectric leg  130  or N-type thermoelectric leg  140  may have a cylindrical shape, a polygonal column shape, an elliptical column shape, or the like. 
     Performance of the thermoelectric device according to one embodiment of the present invention may be expressed as a figure of merit (ZT). The figure of merit (ZT) may be expressed by Equation  1 . 
       [Equation 1] 
         ZT =α2 ·σ·T/k  
 
     Here, α is the Seebeck coefficient [V/K], σ is electric conductivity [S/m], and α2·σ is power factor [W/mK2]. In addition, T is temperature, and k is thermal conductivity [W/mK]. k may be expressed as a·cp·ρ, and a is thermal diffusivity [cm2/S], cp is specific heat [J/gK], and ρ is density [g/cm3]. 
     In order to obtain a figure of merit of a thermoelectric element, a Z value [V/K] is measured using a Z meter, and thus the figure of merit (ZT) may be calculated using the measured Z value. 
     Here, each of the lower electrodes  120  disposed between the lower substrate  110  and the P-type and N-type thermoelectric legs  130  and  140  and the upper electrode  150  disposed between the upper substrate  160  and the P-type and N-type thermoelectric legs  130  and  140  may include at least one among Cu, Ag, Al, and Ni, and may have thicknesses of 0.01 mm to 0.3 mm. In a case in which the thickness of the lower electrode  120  or upper electrode  150  is less than 0.01 mm, an electrode function thereof is degraded, and thus electric conductivity performance thereof may be lowered, and in a case in which the thickness thereof is greater than 0.3 mm, resistance thereof increases, and thus conduction efficiency thereof may be lowered. 
     In addition, each of the lower substrate  110  and the upper substrate  160 , which face each other, may be a metal substrate, and the thickness thereof may be 0.1 mm to 1.5 mm. In a case in which the thickness of the metal substrate is less than 0.1 mm or greater than 1.5 mm, since a radiation or thermal conductivity thereof may become excessively high, the reliability of the thermoelectric element may be degraded. In addition, in the case in which the lower substrate  110  and the upper substrate  160  are the metal substrates, insulating layers  170  may be further formed between the lower substrate  110  and the lower electrodes  120  and between the upper substrate  160  and the upper electrode  150 . The insulating layer  170  may include a material having a thermal conductivity of 1 to 20 W/K. 
     In this case, sizes of the lower substrate  110  and the upper substrate  160  may also be different. For example, a volume, thickness, or area of one of the lower substrate  110  and the upper substrate  160  may be greater than that of the other thereof. Accordingly, the heat absorption or radiation performance of the thermoelectric element can be enhanced. Preferably, at least one among the volume, the thickness, and the area of the lower substrate  110  may be greater than that of the upper substrate  160 . In this case, in a case in which the lower substrate  110  is disposed in a high temperature region for the Seebeck effect or applied as a heating region for the Peltier effect, or in a case in which a sealing member for protecting the thermoelectric device, which will be described below, from the external environment is disposed on the lower substrate  110 , at least one among the volume, the thickness, and the area of the lower substrate  110  may be greater than that of the upper substrate  160 . In this case, the area of the lower substrate  110  may be greater than 1.2 to 5 times that of the upper substrate  160 . In a case in which the area of the lower substrate  110  is less than 1.2 times that of the upper substrate  160 , an effect on improving heat conduction efficiency is not high, and in a case in which the area of the lower substrate  110  is greater than 5 times that of the upper substrate  160 , the heat conduction efficiency may be significantly lowered, and it may be difficult to maintain a basic shape of the thermoelectric module. 
     In addition, a radiation pattern, for example, an irregular pattern, may also be formed on at least one surface of the lower substrate  110  and the upper substrate  160 . Accordingly, the radiation performance of the thermoelectric element can be enhanced. In a case in which the irregular pattern is formed on a surface in contact with the P-type thermoelectric leg  130  or N-type thermoelectric leg  140 , a bonding property between the thermoelectric leg and the substrate can also be improved. The thermoelectric device  100  includes the lower substrate  110 , the lower electrodes  120 , the P-type thermoelectric leg  130 , the N-type thermoelectric leg  140 , the upper electrodes  150 , and the upper substrate  160 . 
     Although not illustrated in the drawings, the sealing member may be further disposed between the lower substrate  110  and the upper substrate  160 . The sealing member may be disposed between the lower substrate  110  and the upper substrate  160  and disposed on side surfaces of the lower electrodes  120 , the P-type thermoelectric leg  130 , the N-type thermoelectric leg  140 , and the upper electrodes  150 . Accordingly, the lower electrodes  120 , the P-type thermoelectric leg  130 , the N-type thermoelectric leg  140 , and the upper electrodes  150  can be sealed from external moisture, heat, contamination, and the like. 
     In this case, the lower substrate  110  disposed on the duct  1100  may be an aluminum substrate, and the aluminum substrate may be bonded to each of the first surface  1110  and the second surface  1120  by a TIM. Since the aluminum substrate has high thermal conduction performance, heat may be easily transferred between one surface of both surfaces of each of the thermoelectric devices  1210  and  1310  and the duct  1100  in which the first fluid flows. In addition, when the aluminum substrate and the duct  1100  in which the first fluid flows are bonded by the TIM, thermal conduction between the aluminum substrate and the duct  110  in which the first fluid flows may not be interfered with. 
     Referring to  FIGS. 1 to 4  again, the first fluid passes through the duct  1100  in a first direction, and a gas may branch off in directions perpendicular to the first direction and parallel to the first surface  1110  and the second surface  1120 . To this end, one gas guide member  1400  may be disposed on each duct  1100  or a plurality of gas guide members may be disposed on each duct  1100  in a direction in which the second fluid is introduced. For example, in a case in which the third surface  1130  of the duct  1100  is formed to face the direction in which the second fluid is introduced and the fourth surface  1140  thereof is formed to face a direction in which the second fluid is discharged, the gas guide member  1400  may be disposed at a side of the third surface  1130  of the duct  1100 . Alternatively, the gas guide member  1400  may also be disposed at a side of the fourth surface  1140  of the duct  1100  according to an aerodynamic principle. 
     In this case, a temperature of a gas introduced into the power generating apparatus is higher than a temperature of the gas discharged after passing through the radiation fin included in the thermoelectric module of the power generating apparatus. For example, the gas introduced into the power generating apparatus may be a gas having waste heat generated by an engine of a vehicle, vessel, or the like but is not limited thereto. For example, a temperature of the gas introduced into the power generating apparatus may be 100° C. or more, preferably 200° C. or more, and more preferably 220° C. to 250° C. but is not limited thereto. 
     The gas guide member  1400  may be disposed above the third surface  1130  of the duct  1100  and have a shape of which a distance from the third surface  1130  is increased in a direction toward a center between both ends of the third surface  1130 . For example, the gas guide member  1400  may have an umbrella or roof shape. Accordingly, the second fluid, for example, waste heat, may branch off due to the gas guide member  1400  and may be guided to come into contact with the first thermoelectric module  1200  and the second thermoelectric module  1300  disposed on both surfaces of the power generating apparatus. 
     Meanwhile, in one power generating apparatus  1000 , a width W 1  between an outer side of the first radiation fin  1220  of the first thermoelectric module  1200  and an outer side of the second radiation fin  1320  of the second thermoelectric module  1300  may be greater than a width W 2  of the gas guide member  1400 . In this case, the outer side of each of the first radiation fin  1220  and the outer side of the second radiation fin  1320  may mean a side opposite to a side facing the duct  1100 . In this case, the first radiation fin  1220  and the second radiation fin  1320  may be formed in directions not to interfere with a gas flow. For example, each of the first radiation fin  1220  and the second radiation fin  1320  may have a plate shape extending in a second direction. Alternatively, each of the first radiation fin  1220  and the second radiation fin  1320  may also have a folded shape to form a flow passage in the second direction in which the gas flows. In this case, a maximum width W 1  between the first radiation fin  1220  of the first thermoelectric module  1200  and the second radiation fin  1320  of the second thermoelectric module  1300  may mean a distance between a furthest point of the first radiation fin  1220  from the duct  1100  and a furthest point of the second radiation fin  1320  from the duct  1100 , and a maximum width W 2  of the gas guide member  1400  may mean a width of the gas guide member  1400  in a region closest to the third surface  1132  of the duct  1100 . Accordingly, a flow of a gas introduced in the second direction may not be interfered with by the gas guide member  1400  and may be directly transferred to the first radiation fin  1220  and the second radiation fin  1320 . Accordingly, since contact areas between the gas and the first radiation fin  1220  and the second radiation fin  1320  are increased, amounts of heat absorbed by the first radiation fin  1220  and the second radiation fin  1320  from the gas can be increased and electricity generation efficiency can be improved. 
     Meanwhile, a thermal insulating member  1700  and a shield member  1800  may be further disposed between the third surface  1130  of the duct  1100  and the gas guide member  1400  to increase a sealing effect and a thermal insulating effect between the first thermoelectric module  1200 , the duct  1100 , and the second thermoelectric module  1300 . 
     Meanwhile, the gas guide member  1400 , the shield member  1800 , the thermal insulating member  1700 , and the third surface  1130  of the duct  1100  may be coupled together, and accordingly, an air layer may be formed between gas guide member  1400  and the shield member  1800 . Due to the air layer between the gas guide member  1400  and the shield member  1800 , thermal insulating performance may be further improved. 
     Alternatively, in order to further improve the thermal insulating performance, an additional insulating member  1740  may also be further disposed between the thermal insulating member  1700  and the shield member  1800 . 
     Alternatively, although not illustrated in the drawings, one surface of the gas guide member  1400  may also extend to have a hollow triangular shape, and accordingly, the gas guide member  1400  may be bonded to the shield member  1800 . 
     Meanwhile, according to the embodiment of the present invention, the first thermoelectric module  1200  disposed on the first surface  1110  of the duct  1100  may be provided as a plurality of first thermoelectric modules  1200 , and the second thermoelectric module  1300  disposed on the second surface  1120  of the duct  1100  may be provided as a plurality of second thermoelectric modules  1300 . Sizes and the number of the thermoelectric modules may be adjusted according to a required amount of generated electricity. 
     In this case, at least some of the plurality of first thermoelectric modules  1200  disposed on the first surface  1110  of the duct  1100  may be electrically connected, and at least some of the plurality of second thermoelectric modules  1300  disposed on the second surface  1120  of the duct  1100  may be electrically connected. To this end, electrical wires are connected to some of the plurality of electrodes included in the thermoelectric devices and drawn out to the outside of the thermoelectric devices and the withdrawn wires may be connected to connectors disposed outside the thermoelectric devices. 
     Meanwhile, the electrical wires and the connectors are weak to external heat or moisture, and in a case in which the second fluid passing through the radiation fin comes into direct contact with the electrical wires and the connectors, the electrical wires and the connectors may be damaged. Accordingly, the power generating apparatus according to the embodiment of the present invention may further include a shield member for covering the electrical wires and the connectors. However, in a case in which the shield member is disposed between the thermoelectric modules, the shield member may interfere with the flow passage of the second fluid. In the embodiment of the present invention, a structure of the shield member is intended to be provided that is capable of covering the electrical wire and the connector even without interfering with the flow passage of the second fluid. 
     The power generating apparatus according to the embodiment of the present invention may include a first shield member  2100  disposed between two adjacent first thermoelectric modules  1200 - 1  and  1200 - 2  of the plurality of first thermoelectric modules  1200  and a second shield member (not shown) disposed between two adjacent second thermoelectric modules  1300 - 1  and  1300 - 2  of the plurality of second thermoelectric modules  1300 . 
       FIG. 8  is a partial perspective view illustrating the power generating apparatus including the shield member according to one embodiment of the present invention,  FIG. 9  is a cross-sectional view illustrating the power generating apparatus of  FIG. 8 ,  FIG. 10  is an enlarged view illustrating a vicinity of the shield member of the power generating apparatus of  FIG. 8 ,  FIG. 11  is a perspective view illustrating the shield member according to one embodiment of the present invention, and  FIG. 12  is a cross-sectional view illustrating the shield member according to one embodiment of the present invention. Repeated contents which are the same as those of  FIGS. 1 to 7  will be omitted. For the sake of convenience in the description, an example of only the plurality of first thermoelectric modules disposed on the first surface of the duct will be described, but the present invention is not limited thereto, and a structure, which is the same as that of the plurality of first thermoelectric modules, may also be applied to the plurality of second thermoelectric modules disposed on the second surface of the duct. 
     Referring to  FIGS. 8 to 12 , the plurality of first thermoelectric modules  1200  are disposed on the first surface  1110  of the duct  1100 . Each of the plurality of first thermoelectric modules  1200  includes the thermoelectric device  1210  disposed on the first surface  1110  and the radiation fin  1220  disposed on the thermoelectric device  1210 . In addition, each of the first thermoelectric modules  1200  includes electrical wires  300  drawn out from the thermoelectric device  1210  and connectors  400  connected to the electrical wires  300 . In this case, the electrical wires  300  may correspond to the lead wires  181  and  182  of  FIG. 6 . 
     The electrical wires  300  drawn out from one thermoelectric device  1210 - 1  included in one first thermoelectric module  1200 - 1  and the electrical wires  300  drawn out from a thermoelectric device  1210 - 2  of the other first thermoelectric module  1200 - 2  adjacent thereto may be connected to the connectors  400 . 
     According to the embodiment of the present invention, the first shield member  2100  may be disposed between one first thermoelectric module  1200 - 1  and the other first thermoelectric module  1200 - 2  adjacent thereto and may cover the electrical wires  300  and the connectors  400  disposed between the one first thermoelectric module  1200 - 1  and the other first thermoelectric module  1200 - 2  adjacent thereto. Accordingly, the electrical wires  300  and the connectors  400  may be disposed between the first surface  1110  of the duct  1100  and the first shield member  2100 . 
     In this case, an insulating member  3000  may be further disposed between the first surface  1110  of the duct  1100  and the first shield member  2100 . Accordingly, since insulation between the first fluid in the duct  1100  and the second fluid on the first shield member  2100  can be maintained, the electricity generation performance of the power generating apparatus can be maximized. 
     For example, the insulating member  3000  may be disposed between the first surface  1110  and the electrical wires  300  and the connectors  400 . Alternatively, the insulating member  3000  may be disposed on the first surface  1110  and side surfaces of the electrical wires  300  and the connectors  400 . In this case, the insulating member  3000  may not be disposed between the electrical wires  300  and the connector  400  and the first shield member  2100 . That is, holes through which the electrical wires  300  and the connectors  400  pass may also be formed in the insulating member  3000 . Accordingly, since a height of the first shield member  2100  due to the insulating member  3000  is not increased, an effect of the insulating member  3000  on a flow of the second fluid can be removed. 
     Accordingly, the second fluid passing through the power generating apparatus according to the embodiment of the present invention may flow to sequentially pass through the first radiation fin  1220 - 1  of one first thermoelectric module  1200 - 1  of two adjacent first thermoelectric modules  1200 - 1  and  1200 - 2 , the first shield member  2100 , and the second radiation fin  1220 - 2  of the other first thermoelectric module  1200 - 2  of two adjacent first thermoelectric modules  1200 - 1  and  1200 - 2 . The direction in which the second fluid flows may be the second direction perpendicular to the first direction in which the first fluid is introduced and discharged from the duct  1100 . 
     Similarly, a second shield member  2200  may be disposed between one second thermoelectric module  1300  and the other second thermoelectric module  1300  adjacent thereto and may cover the electrical wires and the connectors between one second thermoelectric module  1300  and the other second thermoelectric module  1300  adjacent thereto. Accordingly, the electrical wires and the connectors may be disposed between the second surface  1120  of the duct  1100  and the second shield member. In the present specification, for the sake of convenience in the description, the first shield member  2100  is mainly described, but a structure which is the same as a structure of the first shield member  2100  may also be applied to the second shield member  2200 . 
     In this case, the first shield member  2100  according to the embodiment of the present invention includes a first face  2110  and a second face  2120  having a height higher than a height of the first face  2110 . In addition, the first shield member  2100  may further include a third face  2130  having a height higher than the height of the first face  2110  and lower than the height of the second face  2120 . In this case, the first face  2110  may be disposed at the height which is lower than or equal to that of a lower surface  1222  of the radiation fin  1220 . In the present specification, the height may mean a distance in a direction perpendicular to the surface of the duct  1100  with respect to the surface of the duct  1100 . In the case in which the first shield member  2100  is disposed between two adjacent first thermoelectric modules  1200 - 1  and  1200 - 2 , the first face  2110  of the first shield member  2100  may be symmetrically formed between two first thermoelectric modules  1200 - 1  and  1200 - 2 . Accordingly, the second fluid passing through the first radiation fin  1220 - 1  can be introduced into the second radiation fin  1220 - 2  along the first shield member  2100  in a state in which a flow thereof is not interfered with. 
     In addition, the third face  2130  may be disposed at the height higher than that of the electrical wire  300 , and the second face  2120  may be disposed at the height higher than those of electrical wire  300  and the connector  400 . For example, the second face  2120  may be disposed at a maximum height, which is less than 0.25 times, preferably less than 0.2 times, and more preferably less than 0.18 times a height difference H between the lower surface  1222  and an upper surface  1224  of the radiation fin  1220 , from the lower surface  1222  of the radiation fin  1220 . Accordingly, since an area, which is covered by the second face  2120 , of each of the first radiation fin  1220 - 1  and the second radiation fin  1220 - 2  may be minimized, the flow of the second fluid may not be interfered with. 
     In this case, an area of the third face  2130  may be greater than an area of the second face  2120 . That is, the second face  2120  may be formed to cover the connector  400 , and an entire region excluding the first face  2110  and the second face  2120  may be the third face  2130 . As illustrated in the drawings, the first face  2110  may be formed along the first radiation fin  1220 - 1  and the second radiation fin  1220 - 2 . In addition, the second face  2120 - 1  may be formed to cover a first connector connected to the electrical wire, which is drawn out from one first thermoelectric module  1200 - 1  and has one polarity of a first polarity and a second polarity, and a second connector connected to the electrical wire drawn out from the other first thermoelectric module  1200 - 2  and having one polarity of the first polarity and the second polarity. In addition, the second face  2120 - 2  may be formed to cover a third connector connected to the electrical wire, which is drawn out from one first thermoelectric module  1200 - 1  and having the other polarity of the first polarity and the second polarity, and a fourth connector connected to the electrical wire drawn out from the other first thermoelectric module  1200 - 2  and having the other polarity of the first polarity and the second polarity. As described above, the second face  2120  may include a plurality of second faces  2120 - 1  and  2120 - 2  spaced apart from each other. In this case, the first connector and the second connector may be one connector or separate connectors, and the third connector and the fourth connector may be one connector or separate connectors. 
     In addition, an entire region excluding the first face  2110  and the second face  2120  of the first shield member  2100  may be the third face  2130 . In the case in which the second face  2120  includes the plurality of second faces spaced apart from each other, the third face  2130  may be disposed between two spaced second faces  2120 - 1  and  2120 - 2 . Accordingly, since an area of the second face  2120  may be minimized, the first shield member  2100  may not interfere with a gas passage from the first radiation fin  1220 - 1  to the second radiation fin  1220 - 2 . 
     Meanwhile, according to the embodiment of the present invention, the first shield member  2100  includes a first connecting face  2140  connecting the first face  2110  and the third face  2130  and a second connecting face  2150  connecting the third face  2130  and the second face  2120 . 
     In this case, the first connecting face  2140  may be inclined at an angle θ 1  greater than 0° and less than 90° , preferably greater than 10° and less than 75°, and more preferably greater than 20° and less than 60° with respect to the first face  2110 . Similarly, the second connecting face  2150  may be inclined at an angle θ 2  greater than 0° and less than 90°, preferably greater than 10° and less than 75°, and more preferably greater than 20° and less than 60° with respect to the second face  2120 . Accordingly, a gas passing through the first radiation fin  1220 - 1  may be introduced into the second radiation fin  1220 - 2  along the first shield member  2100  without great resistance. 
     Meanwhile, in the case in which the third face  2130  is disposed between two adjacent second faces  2120 - 1  and  2120 - 2 , a second connecting face  2150 - 1  and a second connecting face  2150 - 2  may be symmetrically disposed to connect the third face  2130  to the second face  2120 - 1  and the third face  2130  to the second face  2120 - 2 , respectively. 
     Hereinafter, a simulation result of a gas flow when the shield member according to the embodiment of the present invention is used will be described. 
       FIG. 13  is a set of a top view and a cross-sectional view illustrating a shield member according to a comparative example,  FIG. 14  is a view illustrating a height difference between the shield member and a radiation fin according to the comparative example of  FIG. 13 , and  FIGS. 15A to 15C  are views illustrating a flow of a gas passing through the shield member according to the comparative example; 
       FIG. 16  is a set of a top view and a cross-sectional view illustrating the shield member according to the embodiment of the present invention,  FIG. 17  is a view illustrating a height difference between the shield member and the radiation fin according to the embodiment of  FIG. 16 , and  FIGS. 18A to 18C  are views illustrating a flow of a gas passing through the shield member according to the embodiment of  FIG. 16 . 
     In this case, a simulation was performed under conditions in which, on the basis of the first surface  1110  of the duct  1100 , a height difference between a lower surface and an upper surface of the radiation fin is 6.5 mm, and a height of a connector  400  is 3 mm, and a height of an electrical wire  300  is 2.6 mm, and a height of an insulating member is 1.4 mm, and a thickness of the shield member is 0.5 mm. 
     According to the comparative example of  FIGS. 13 to 15 , a gap between the shield member and the connector was set as 2 mm, a gap between the shield member and the electrical wire was set as 2.4 mm, and accordingly, it was seen that a fin open height of the radiation fin, that is, a height difference between an upper surface of the shield member and the upper surface of the radiation fin was 3.6 mm, a fin open area of the radiation fin, that is, an area of the open radiation fin from the upper surface of the shield member to the upper surface of the radiation fin was 55.4% of a maxim fin open area of the radiation fin, that is, an open area from the lower surface to the upper surface of the radiation fin. 
     According to the embodiment of  FIGS. 16 to 18 , a gap between the shield member and the connector was set as 1 mm, a gap between the shield member and the electrical wire was set as 0.6 mm, and accordingly it was seen that a pin open height of radiation fin from the third face was 5.4 mm, a pin open height of the radiation fin from the second face is 4.6 mm, and a fin open area of the radiation fin is 79.4% of a maximum fin open area of the radiation fin. 
     Accordingly, when the shield member according to the embodiment of the present invention is used, since the fin open area of the radiation fin is increased, a problem in that a gas flow is interfered with by the shield member can be minimized. 
     Particularly, a gas flow in a structure illustrated in  FIG. 13  was simulated,  FIG. 15B  is an enlarged view illustrating a pressure vector of a gas flowing in a region A of  FIG. 15A , and  FIG. 15C  is an enlarged view illustrating a pressure streamline of the gas flowing in the region A. In addition, a gas flow in a structure illustrated in  FIG. 16  was simulated,  FIG. 18B  is an enlarged view illustrating a pressure vector of a gas flowing in a region A of  FIG. 18A , and  FIG. 18C  is an enlarged view illustrating a pressure streamline of the gas flowing in the region A of  18 A. 
     In  FIG. 15B , a distribution of pressure vectors in a region A 1  (in which the gas passes through the radiation fin) was 1.493e+005 to 1.495e+005 Pa, a distribution of pressure vectors in a region A 2  (in which the gas passes through the shield member) was about 1.488e+005 Pa, and a distribution of pressure vectors in a region A 3  (in which the gas passes through the radiation fin) was about 1.490e+005 Pa. In addition, in  FIG. 15C , a distribution of pressure streamlines in the region A 1  (in which the gas passes through the radiation fin) was 1.493e+005 to 1.495e+005 Pa, a distribution of pressure streamlines in the region A 2  (in which the gas passes through the shield member) was about 1.488e+005 Pa, and a distribution of pressure streamlines in the region A 3  (in which the gas passes through the radiation fin) was about 1.490e+005 Pa. 
     In addition, in  FIG. 18B , a distribution of pressure vectors in a region A 1  (in which the gas passes through the radiation fin) was 1.493e+005 to 1.495e+005 Pa, a distribution of pressure vectors in a region A 2  (in which the gas passes through the shield member) was about 1.490e+005 Pa, and a distribution of pressure vectors in a region A 3  (in which the gas passes through the radiation fin) was about 1.490e+005 Pa. 
     In addition, in  FIG. 18C , a distribution of pressure streamlines in the region A 1  (in which the gas passes through the radiation fin) was 1.493e+005 to 1.495e+005 Pa, a distribution of pressure streamlines in the region A 2  (in which the gas passes through the shield member) was about 1.490e+005 Pa, and a distribution of pressure streamlines in the region A 3  (in which the gas passes through the radiation fin) was about 1.490e+005 Pa. 
     Accordingly, in the case in which the shield member according to the embodiment of the present invention is used, a gas passing through two adjacent thermoelectric modules can flow more smoothly. 
     According to the embodiments of the present invention, a power generating apparatus with high electricity generation performance can be obtained. Particularly, according to the embodiments of the present invention, the power generating apparatus of which assembly is simple and the electricity generation performance is high can be obtained by reducing the number of using components and an occupying volume. 
     In addition, according to the embodiments of the present invention, the power generating apparatus of which heat conduction efficiency to a thermoelectric device is improved can be obtained. In addition, according to the embodiments of the present invention, an electricity generation capacity can be adjusted by adjusting the number of power generating apparatuses. 
     In addition, according to the embodiments of the present invention, an area at which a second fluid comes into contact with a radiation fin of a thermoelectric module can be maximized, and thus, electricity generation efficiency can be maximized. 
     While the invention has been described with reference to the exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.