Patent Publication Number: US-2017356692-A1

Title: Finned Heat Exchanger

Description:
This invention was made with Government support under Contract No. DE-AC09-08SR22470, awarded by the U.S. Department of Energy. The Government has certain rights in the invention. 
    
    
     BACKGROUND OF THE INVENTION 
     Heat exchangers are employed in a variety of applications for transferring heat, such as from one fluid to another or from a device such as a heating element to a fluid. These heat exchangers can be manufactured having various configurations including, but not limited to, tube in tube (or pipe in pipe) heat exchangers, finned heat exchangers, etc. In particular, regarding the latter, the finned heat exchangers typically employ fins which extend radially toward the central axis from an inner surface of a tube or pipe. In addition, some of these finned heat exchangers consist of a single tube or pipe containing fins which extend radially outward from an outer surface of the tube or pipe and into the open environment. While these heat exchangers may have their own benefits, they certainly leave a lot to be desired. For instance, these heat exchangers may not provide the desired heat exchange capacity and heat transfer rate and thus may not be particularly efficient. 
     As a result, there is a need to provide an improved heat exchanger that is capable of providing an improved heat exchange capacity and heat transfer rate. 
     SUMMARY OF THE INVENTION 
     Aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention. 
     In accordance with one embodiment of the present invention, a finned heat exchanger is disclosed. The finned heat exchanger comprises an inner annulus, an outer annulus, a plurality of fins, and an outer chamber. The inner annulus defines an inner chamber and the inner annulus has an inner surface and an outer surface. The outer annulus has an inner diameter that is larger than an outer diameter of the inner annulus and the outer annulus has an inner surface and an outer surface. The plurality of fins extends radially outward from the outer surface of the inner annulus toward the inner surface of the outer annulus. The outer chamber is located between the inner annulus and the outer annulus. The plurality of fins is located within the outer chamber. 
     In accordance with another embodiment of the present invention, a method of heating or cooling a fluid is disclosed. The method comprises a step of transferring a first fluid through the inner chamber and a second fluid through the outer chamber of the finned heat exchanger. 
     In accordance with another embodiment of the present invention, a method of forming a finned heat exchanger is disclosed. The method comprises (a) using a computer-based system to operate upon data that corresponds to a geometric configuration of the finned heat exchanger and configuring a forming device to deposit a material and receive instructions related to the data such that upon receipt of the instructions, the forming device builds up the finned heat exchanger with the material. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
         FIG. 1  provides a cross-section of the heat exchanger as disclosed herein; and 
         FIG. 2  provides an enlarged view of a fin of the heat exchanger disclosed herein. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     Generally speaking, the present invention is directed to a heat exchanger. In particular, the present invention is directed to a finned heat exchanger comprising a plurality of fins as defined and illustrated herein. 
     The present inventors have discovered that a finned heat exchanger as disclosed herein is capable of providing an improved heat exchange capacity and heat transfer rate in comparison to many conventional heat exchangers, such as some conventional finned heat exchangers and/or tube in tube (or pipe in pipe) heat exchangers. To that extent, the finned heat exchanger as disclosed herein is capable of providing a more efficient means of transferring heat between fluids, such as between liquids, gases, or a combination thereof and/or heat between a device or element and a fluid. 
       FIG. 1  illustrates a cross section of the finned heat exchanger  10  disclosed herein. In particular, the finned heat exchanger  10  comprises an inner annulus  20  and an outer annulus  30 . The inner annulus  20  has an inner surface proximal to the center of the finned heat exchanger. The inner annulus  20  also has an opposing outer surface facing the inner surface of the outer annulus  30 . The outer annulus  30  has an inner surface facing the outer surface of the inner annulus  20 . The outer annulus  30  also has an opposing outer surface facing away from the center of the finned heat exchanger. 
     The inner annulus  20  is located closer to the center of the finned heat exchanger  10 . In this regard, the outer annulus  30  has an inner diameter that is larger than the outer diameter of the inner annulus  20 . For instance, the outer diameter of the inner annulus  20  is determined from the position at which the channels  80  between the fins  60  begin. In one embodiment, the inner annulus  20  and the outer annulus  30  are positioned so that they are concentric. 
     The inner annulus  20  defines an inner or central chamber  40 . The chamber  40  is employed for transferring a first working fluid which can be heated and/or cooled while traversing through the finned heat exchanger. In this regard, a first fluid may pass through the chamber  40  defined by the inner annulus  20 . The chamber  40  may have a circular configuration or shape. 
     The space between the outer surface of the inner annulus  20  and the inner surface of the outer annulus  30  defines an outer chamber  50 . The chamber  50  is employed for transferring a second working fluid which can be heated and/or cooled while traversing through the finned heat exchanger. In this regard, a second fluid may pass through the chamber  50  defined by the space between the outer surface of the inner annulus  20  and the inner surface of the outer annulus  30 . 
     As illustrated in  FIG. 1 , the finned heat exchanger includes a plurality of fins  60 . Without intending to be limited by theory, it is believed that the surface area of the fins allows for a desired heat exchange rate and capacity. 
     In general, the fins  60  extend radially outward from the outer surface of the inner annulus  20  and toward the inner surface of the outer annulus  30 . However, the fins  60  do not extend all the way to the outer annulus  30  such that the fins  60  do not directly contact the inner surface of the outer annulus  30 . For instance, the fins  60  may extend 40% or more, such as 50% or more, such as 55% or more, such as 60% or more, such as 65% or more, such as 70% or more, such as 75% or more, such as 80% or more, such as 85% or more, such as 90% or more and less than 100%, such as 95% or less, such as 90% or less, such as 85% or less, such as 80% or less the distance in the radial direction between the outer surface of the inner annulus  20  and the inner surface of the outer annulus  30 . 
     In one embodiment, the fins  60  may extend radially from the inner surface of the inner annulus  20  toward the center of the finned heat exchanger  10 . In one embodiment, the fins  60  may extend radially from the outer surface of the inner annulus  20  as indicated above and a second set of fins may extend radially from the inner surface of the inner annulus  20  toward the center of the finned heat exchanger  10 . 
     In general, allowing the fins to extend in the manner as indicated above can provide certain advantages. For instance, without intending to be limited by theory, a heat exchanger may be less likely to fail during low cycle fatigue, unlike those in which the fins extend and contact both the inner annulus and the outer annulus (i.e., 100% extension). However, it should be understood that various other benefits can be recognized by configuring the fins in a manner as disclosed herein. 
     The configuration of the fins  60  can be better demonstrated by reference to  FIG. 2 . The fins  60  have a first end  100  located proximally to the inner annulus  20  and a second and opposite end  110  located proximally to the outer annulus  30 . The first end  100  may be considered the location at which the fin extends from the outer surface of the inner annulus  20 . The fins  60  have a length (l) which is the length from the outer surface of the inner annulus  20  to the second end  110  of the fins  60 . In addition, the fins also have a thickness (t) which may vary along the length of the fins  60 . 
     In one embodiment, along the length (l) of the fins  60 , the thickness (t) of the fin increases from the point of formation of the arc of the channel  80  up until the formation of the arc at the second end  110 . The channel  80  forms an arc adjacent the inner annulus  20  and the fins form an arc at the second end  110  and proximally to the outer annulus  30 . For instance, at some length along the fins, the arc of the channels begins to form and the arc of the fins begins to form. In one embodiment, the thickness of the fins at the point of formation of the arc of the channels is less than the thickness of the fins at the point of formation of the arc of the fins. 
     For instance, across the entire length (l) of the fins  60  when going from end  100  toward end  110 , the thickness (t) of the fins  60  increases across 50% or more, such as 60% or more, such as 70% or more, such as 80% or more of the length (l) of the fins  60 . 
     In one embodiment, when going from the inner end  100  toward the outer end  110 , the thickness (t) of the fins  60  at ½ of the length of the fins  60  is less than the thickness (t) at ¾ of the length of the fins  60  and greater than the thickness (t) at ¼ of the length (l) of the fins  60 . 
     In one embodiment, when going from the inner end  100  toward the outer end  110 , the average thickness of the first quarter of the length (l) of the fins  60  is less than the average thickness of the second quarter, third quarter, and the fourth quarter of the length (l) of the fins  60 . In this regard, the average thickness of the fourth quarter of the length (l) of the fins  60  is greater than the average thickness of the first quarter, second quarter, and third quarter of the length (l) of the fins  60 . 
     Similarly, in one embodiment, when going from the inner end  100  toward the outer end  110 , the average thickness of the first third of the length (l) of the fins  60  is less than the average thickness of the second third and final third of the length (l) of the fins  60 . In this regard, the average thickness of the final third of the length (l) of the fins  60  is greater than the average thickness of the first third and the second third of the length (l) of the fins  60 . 
     In one embodiment, the thickness (t) of the fins  60  located proximally to the outer annulus  30  is greater than the thickness (t) of the fins  60  at an area located proximally to the inner annulus  20 . In one embodiment, the thickness (t) of the fins  60  increases gradually over the length (l) of the fins  60 . In another embodiment, the thickness (t) of the fins  60  does not increase gradually over the length (l) of the fins  60 . 
     In one embodiment, the fins  60  have a symmetrical cross-section, such as along the radial direction. In one embodiment, the second ends  110  located proximal to the outer annulus  30  may have an arc shaped configuration. However, without intending to be limited, the second ends  100  may have any other configurations employed in the art, such as a beveled edge configuration, a straight edge configuration, etc. 
     In addition, in one embodiment, the fins  60  do not have a convex configuration along the length of the fins  60 . In one embodiment, the fins  60  do not have a concave configuration along the length of the fins  60 . In one embodiment, the fins  60  do not have a convex configuration or a concave configuration along the length of the fins  60 . 
     In one embodiment, the fins  60  are arranged so that their radial lines pass orthogonally through the central axis of the finned heat exchanger. In this regard, the fins  60  are oriented so that they are parallel to the axial direction of the finned heat exchanger. That is the fins  60  extend along the axial direction of the finned heat exchanger and outwardly in the radial direction of the finned heat exchanger. For instance, in on embodiment, the fins  60  do not form a helical path about the central axis of the finned heat exchanger. In this regard, the fins  60  have a 0 degrees twist about the longitudinal or central axis of the finned heat exchanger. Within a chamber, the fins  60  may be uniformly spaced apart from each other. 
     The finned heat exchanger may include 5 or more, such as 10 or more, such as 15 or more, such as 20 or more fins in at least one outer chamber. Overall, the finned heat exchanger may include 10 or more, such as 20 or more, such as 30 or more, such as 40 or more fins. However, it should be understood that the heat exchanger may include any number of fins based on the size of the finned heat exchanger and the desired heat exchange capacity and heat transfer rate. 
     In one embodiment, the finned heat exchanger may contain at least two outer chambers  50  containing fins  60 . For instance, the space between the inner annulus  10  and the outer annulus  30  may be partitioned to create at least 2, such as at least 3, such as at least 4, such as at least 5 chambers. The fins  60  may be present in at least one outer chamber. In one embodiment, the fins  60  may be present in at least two outer chambers, such as at least three outer chambers, such as at least four outer chambers. However, it should be understood that not all of the outer chambers need to contain fins  60 . For instance, it should be understood that at least one outer chamber, such as at least two outer chambers, such as at least three outer chambers, such as at least four outer chambers may not contain any fins  60 . 
     In addition, as illustrated in  FIG. 1 , a connecting body  90  may be utilized to connect or bridge the inner annulus  20  to the outer annulus  30 . In particular, the connecting body  90  may be utilized to connect or bridge the outer surface of the inner annulus  20  to the inner surface of the outer annulus  30 . The connecting body  90  may define a body chamber  70 . In this regard, a body chamber  70  is a chamber that is surrounded by the connecting body  90 . The connecting body  90  may include at least one body chamber  70 , such as at least two body chambers  70 , such as at least three body chambers  70 . When employing at least two body chambers  70 , one body chamber may have a diameter that is smaller than the second body chamber. 
     The body chambers may be utilized to provide various benefits and/or may be equipped to contain certain elements or devices. For instance, at least one body chamber may be utilized to provide a thermocouple probe for measuring the temperature. In particular, when body chambers having different sizes (e.g., diameters) are employed, the smaller chamber may be equipped with a thermocouple probe. 
     At least one body chamber may be utilized to provide a heating element, such as an electrical heating element. The fluid traversing through the heat exchanger may be heated via the heat element employed in the body chamber. In particular, when body chambers having different sizes (e.g., diameters) are employed, the larger chamber may be equipped with a heating element. 
     In addition, the finned heat exchanger may also be configured to include various other components. For instance, the finned heat exchanger may be configured to include a flowmeter to gauge the flow of any of the fluids that pass through the chamber(s). 
     The finned heat exchanger may include at least one connecting body  90 , such as at least two connecting bodies  90 , such as at least three connecting bodies  90 , such as at least four connecting bodies  90 . It should be understood that each or all of the additional connecting bodies may also contain respective body chambers  70  as described herein. For instance, each connecting body may contain more than one body chamber  70 , such as at least two body chambers  70  as described herein. 
     It should be understood that the finned heat exchanger disclosed herein may be manufactured using any method known in the art. 
     In one embodiment, the inner annulus  20 , the outer annulus  30 , the fins  60 , and the connecting body  90  are integrally formed. That is, they consist of a single unitary body. For instance, the components are formed from one process and are integrally connected. That is, in one embodiment, the inner annulus  20 , the outer annulus  30 , the fins  60 , and the connecting body  90  are not manufactured separately and thereafter combined or connected. In this regard, the finned heat exchanger may be comprised of a single body containing the inner annulus  20 , the outer annulus  30 , the fins  60 , and the connecting body  90 . 
     In one embodiment, the finned heat exchanger may be formed via an extrusion process. Such extrusion process may employ a die to allow the components of the finned heat exchanger to be integrally formed and/or connected. 
     In another embodiment, the finned heat exchanger may be formed via a 3-D printing or additive manufacturing process using techniques generally known in the art. When employing additive manufacturing, the finned heat exchanger is built up layer upon layer as part of a printing process. In particular, the printing device reads data pertaining to a model and then lays down successive layers of a material such that it builds up the object from a series of cross sections. The materials are joined or fused so as to create the final object. The various techniques for employing additive manufacturing are disclosed in WO 2013/163398 to Schevets and WO 2015/022527 to Potter, both of which are incorporated herein by reference in their entirety. 
     In particular, without intending to be limited by theory, additive manufacturing can be conducted by using a computer-based system to operate upon data that corresponds to a geometric configuration of the finned heat exchanger and configuring a forming device to deposit a material and receive instructions related to the data such that upon receipt of the instructions, the forming device builds up the finned heat exchanger with the material. The forming device may be a 3-D printer such that the 3-D printer builds up the finned heat exchanger in a layer-by-layer deposition of the material. 
     The material used to form the 3-D printed finned heat exchanger may be any material generally employed in the art. For instance, the material used to form the 3-D printed finned heat exchanger may be a metal powder or a polymer. For instance, the metal powder may be any metal employed in the art for additive manufacturing, such as steel, stainless steel, an iron-based alloy, a cobalt-chrome alloy, a nickel-based alloy, and/or a titanium alloy. The polymer may be any polymer employed in the art for additive manufacturing, such as acrylonitrile butadiene styrene, polycarbonate, and/or nylon. 
     Without intending to be limited, the finned heat exchanger disclosed herein may be employed in various industries and for various applications. For instance, the finned heat exchanger may be employed in any gas process plant, in particular one that may require a more rapid and efficient heat transfer. The finned heat exchanger may also be employed throughout the manufacturing and power industries. In addition, the finned heat exchanger may also be implemented into a thermal cycling absorption process (TCAP), such as in a chromatographic process for hydrogen isotope separation. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.