Patent Publication Number: US-11656038-B2

Title: Heat exchanger with enhanced end sheet heat transfer

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a division of U.S. application Ser. No. 16/126,794 filed Sep. 10, 2018, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     The following description relates to heat exchangers and, more specifically, to a heat exchanger with end sheet enhancements that provide for enhanced heat transfer. 
     Heat exchangers are typically devices that bring two physical elements, such as hot and cold fluids, into thermal communication with each other. A heat exchanger in a fan duct stream of an engine, the hot fluid could be hot air and the cold fluid could be a cooler air stream. The hot air is flown through tubes extending throughout the heat exchanger and the air stream is directed through a duct and toward fins of the heat exchanger which are thermally communicative with the tubes. In this way, heat of the hot air is transferred to the material of the tubes, from the tubes to the fins and from the fins to the air stream. The temperature of the hot air is thus reduced while the temperature of the air stream can be increased. 
     Currently, heat exchangers are being manufactured so that they tend to transfer an increasing amount of heat and so that they can be more effective as system loads increase while installation volumes decrease. 
     BRIEF DESCRIPTION 
     According to an aspect of the disclosure, a heat exchanger with increased heat transfer capability is provided. The heat exchanger includes first and second end plates, tubes extending between the first and second end plates and fins disposed between the tubes. The heat exchanger is disposable within and differs in shape from a space defined between first and second walls such that end corners of the first end plate abut the first wall and a point of the second end plate abuts the second wall, the first wall diverges from the end corners of the first end plate to define a first open region and the second wall diverges from the point of the second end plate to define second open regions. At least one of the first end plate and the second end plates includes enhancements fluidly communicative with the at least one corresponding one of the first open region and the second open regions. 
     In accordance with additional or alternative embodiments, the space is annular and the heat exchanger is rectangular. 
     In accordance with additional or alternative embodiments, the first open region is an annular segment and the second open regions have an increasing dimension with increasing distance from the point of the second plate. 
     In accordance with additional or alternative embodiments, the first end plate and the second end plates include enhancements fluidly communicative with the first open region and the second open regions, respectively. 
     In accordance with additional or alternative embodiments, the enhancements comprise external fins. 
     In accordance with additional or alternative embodiments, the enhancements include dimpled features. 
     In accordance with additional or alternative embodiments, the enhancements include surface texturing. 
     According to an aspect of the disclosure, a heat exchanger with increased heat transfer capability is provided and includes first and second end plates, tubes extending between the first and second end plates and fins disposed between the tubes. The heat exchanger is disposable within and differs in shape from a space defined between first and second walls such that end corners of the first end plate abut the first wall and a point of the second end plate abuts the second wall, the first wall diverges from the end corners of the first end plate to define a first open region and the second wall diverges from the point of the second end plate to define second open regions. The first end plate and the second end plates include enhancements fluidly communicative with the first open region and with the second open regions, respectively. 
     In accordance with additional or alternative embodiments, the space is annular and the heat exchanger is rectangular. 
     In accordance with additional or alternative embodiments, the first open region is an annular segment and the second open regions have an increasing dimension with increasing distance from the point of the second plate. 
     In accordance with additional or alternative embodiments, the enhancements include external fins. 
     In accordance with additional or alternative embodiments, the enhancements include dimpled features. 
     In accordance with additional or alternative embodiments, the enhancements include surface texturing. 
     According to another aspect of the disclosure, a duct system is provided and includes a duct defining a space between first and second walls and a heat exchanger with increased heat transfer capability. The heat exchanger includes first and second end plates, tubes extending between the first and second end plates and fins disposed between the tubes. The heat exchanger is disposable within and differs in shape from the space with end corners of the first end plate abutting the first wall, a point of the second end plate abutting the second wall, the first wall diverging from the end corners of the first end plate to define a first open region and the second wall diverging from the point of the second end plate to define second open regions. The first end plate and the second end plates include enhancements fluidly communicative with the first open region and with the second open regions, respectively. 
     In accordance with additional or alternative embodiments, the duct includes a conical duct. 
     In accordance with additional or alternative embodiments, the space is annular and the heat exchanger is rectangular. 
     In accordance with additional or alternative embodiments, the first open region is an annular segment and the second open regions have an increasing dimension with increasing distance from the point of the second plate. 
     In accordance with additional or alternative embodiments, the enhancements include external fins. 
     In accordance with additional or alternative embodiments, the enhancements include dimpled features. 
     In accordance with additional or alternative embodiments, the enhancements include surface texturing. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter, which is regarded as the disclosure, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG.  1    is an axial view of a heat exchanger with end sheets that are capable of providing enhanced heat transfer in a fan duct in accordance with embodiments; 
         FIG.  2    is a side view of the heat exchanger of  FIG.  1    taken along line  2 - 2 ; 
         FIG.  3    is a schematic illustration of an end plate with enhancements in accordance with embodiments; 
         FIG.  4    is a schematic illustration of an end plate with enhancements in accordance with embodiments; and 
         FIG.  5    is a schematic illustration of an end plate with enhancements in accordance with embodiments. 
     
    
    
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     DETAILED DESCRIPTION 
     For heat exchangers with an open, non-ducted inlet (e.g., heat exchangers in a fan duct stream of an engine), heat transfer occurs not only within the heat exchanger, but also along the end sheets. The end sheets can be manufactured to enhance the heat transfer through the end sheet by enhancements including, but not limited to, at least one or more of dimpling, the additional of external fins, chemical etching and knurling of the external surfaces of the end sheets. For a more typical ducted configuration, the end sheets contribute a negligible amount of heat transfer capability despite the fact that these end sheets are likely to see similar flows to that of the finned passages and can be expected to achieve heat transfer performance similar to a flat plate. Adding heat transfer features to the end sheets can therefore provide a significant improvement to heat exchanger thermal performance with minimal increases to heat exchanger volumes. 
     With reference to  FIGS.  1  and  2   , a duct system  101  is provided and may be configured as a duct for an air stream generated by a fan in an engine, for example. 
     The duct system  101  includes a duct  110  in which a space  111  is defined between a first wall  112  and a second wall  113 . The first wall  112  can be an annular wall and the second wall  113  can be an annular wall that is smaller than and disposed within the first wall  112  such that the space  111  is an annular space. In addition, as shown in  FIG.  2   , the duct  110  can be provided as a conical duct  115  (see  FIG.  1   ) in which the first and second walls  112  and  113  are angled relative to a central longitudinal axis A. 
     While the duct  110  could be configured as a duct for an air stream generated by a fan in an engine, for example, the duct  110  could also be configured as another type of duct or manifold for various applications. For purposes of clarity and brevity, however, the following description will relate to the case in which the duct  110  is a conical duct for an air stream generated by a fan in an engine. 
     The duct system  101  further includes a heat exchanger  120  that is disposable within the space  111 . The heat exchanger  120  includes a first end plate  121 , a second end plate  122 , tubes  123  extending between the first and second end plates  121  and  122  and fins  124 . The fins  124  are disposed between the tubes  123  and exposed to the air stream with the heat exchanger  120  installed within the space  111 . The heat exchanger  120  further includes an inlet  125 , such as an inlet duct, and an outlet  126 , such as an outlet duct. During operations of the heat exchanger, fluid is received via the inlet  125 , passes through the tubes  123  and exits via the outlet  126 . In the exemplary case in which the fluid is hot, such as the case in which the fluid is a heated air, and the air stream is relatively cold, heat from the hot air is transferred into the material of the tubes  123 , and then into the fins  124  and finally into the air stream as the air stream flows over and around the fins  124 . 
     While the heat exchanger  120  is disposable within the space  111 , the heat exchanger  120  has a different shape from the space  111 . For example, where the space  111  is annular, the heat exchanger  120  may have a rectangular shape (i.e., the first and second end plates  121  and  122  are parallel, the same length and lined up with one another). As such, when the heat exchanger  120  is disposed in the space  111 , opposite end corners  1211  and  1212  of the first end plate  121  abut the first wall  112  and a point  1221  of the second end plate  122  abuts the second wall  113 . Here, the first wall  112  diverges from the opposite end corners  1211  and  1212  of the first end plate  121  to define a first open region  130  with an annular segment shape between the opposite end corners  1211  and  1212  and the second wall  113  diverges from the point  1221  of the second end plate  122  to define second open regions  131  and  132  on either side of the point  1221 . The second open regions have an increasing dimension (i.e., a geometrically increasing depth from end plate  122 ) with an increasing distance from the point  1221  of the second plate  122 . 
     Normally, with rectangular heat exchangers, flows of the air stream will flow through the first open region  130  and the second open regions  131  and  132  but the first open region  130  and the second open regions  131  and  132  would nevertheless be empty of heat exchanger components. Thus, an opportunity for making use of the flows in those regions for additional heat transfer is lost. As shown in  FIGS.  1  and  2   , however, at least one of the first end plate  121  and the second end plate  122  includes enhancements  140 . The enhancements are fluidly communicative with the corresponding at least one of the first open region  130  and the second open regions  131  and  132  and provide for additional heat transfer capability. 
     With continued reference to  FIGS.  1  and  2    and with additional reference to  FIGS.  3 - 5   , the enhancements  140  may include at least one or more of external fins  141  (see  FIG.  3   ), dimpled features  142  (see  FIG.  4   ) and surface texturing  143  (see  FIG.  5   ) due to chemical etching or knurling. 
     Technical effects and benefits of the present disclosure are the provision of a heat exchanger having end plates that provide for enhanced heat transfer particularly for those cases in which the shape of the heat exchanger differs from a shape of the space in which the heat exchanger is disposed. 
     While the disclosure is provided in detail in connection with only a limited number of embodiments, it should be readily understood that the disclosure is not limited to such disclosed embodiments. Rather, the disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the disclosure. Additionally, while various embodiments of the disclosure have been described, it is to be understood that the exemplary embodiment(s) may include only some of the described exemplary aspects. Accordingly, the disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.