Abstract:
The plate-fin heat exchanger includes a first fluid pathway running along a first axis, a second fluid pathway running along a second axis perpendicular to the first axis, and a blocker bar having an inlet face and an outlet face. The blocker bar inlet face coincides with a heat exchanger face. The blocker bar is at an inlet of the second fluid pathway and receives a second fluid. The outlet face of the blocker bar is at the inlet of the second fluid pathway. The blocker bar includes a set of spaced apart pores that extend from the inlet face to the outlet face.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention generally relates to high-temperature plate-fin heat exchangers. Such heat exchangers may include a cold fluid pathway and a hot fluid pathway. The heat exchanger may be used to heat cold fluid (e.g., outside air) and/or cool hot fluid (e.g., cooling fluid from an engine). Plate-fin heat exchangers may operate with any combination of fluids (gas, liquid, or two-phase fluid). The hot fluid may include transient changes in temperature due to various operating conditions (e.g., increased heat from engine throttling). 
     Such transient changes in temperature create gradients throughout the heat exchanger that may cause degraded performance and/or operating life due to thermal fatigue of tube sheets with the heat exchanger. High-temperature heat exchangers may be especially susceptible to fatigue at the hot/hot corner (the corner at the hot inlet and cold outlet) and the hot/cold corner (the corner at the hot inlet and the cold inlet). 
     Accordingly, there is a need for a heat exchanger with improved resistance to thermal fatigue. 
     In one aspect of the present invention, a plate-fin heat exchanger adapted to reduce thermal fatigue, includes a cold fluid pathway running along a first axis, a hot fluid pathway running along a second axis perpendicular to the first axis, and at least one porous blocker bar running along the first axis, where the porous blocker bar includes a set of pores adapted to control flow along the hot fluid pathway and coupled to an inlet of the hot fluid pathway. 
     In another aspect of the present invention, a porous blocker bar adapted for use in a plate-fin heat exchanger includes a front face, a rear face, and multiple pores, each of the pores spanning from the front face to the rear face. 
     In yet another aspect of the present invention, a method of configuring a porous blocker bar for use in a plate-fin heat exchanger includes: receiving dimensional parameters, evaluating the received parameters, calculating design parameters at least partly based on the received parameters, and storing the calculated design parameters. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a perspective view of a section of a plate-fin heat exchanger; 
         FIG. 2  illustrates a perspective view of a section of a plate-fin heat exchanger including a porous blocker bar according to an exemplary embodiment of the present invention; 
         FIG. 3  illustrates a detailed perspective view of the porous blocker bar of  FIG. 2 ; 
         FIG. 4  illustrates a top view of a section of the porous blocker bar of  FIG. 2 , specifically highlighting the size and spacing of pores along the porous blocker bar; 
         FIG. 5  illustrates a flow chart of a conceptual process used in some embodiments to configure various physical parameters of the porous blocker bar of  FIG. 2 ; and 
         FIG. 6  illustrates a schematic diagram of a conceptual system used in some embodiments to implement the process of  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
     Various inventive features are described below that can each be used independently of one another or in combination with other features. Broadly, embodiments of the present invention generally provide a way to reduce fatigue experienced by components of a heat exchanger and improve temperature gradients within the heat exchanger. The porous blocker bars of the present invention may be configured such that structural integrity of the heat exchanger may be improved and hot flow may be reduced and/or dampened. In this manner, the operating life and performance of the heat exchanger may be improved. 
       FIG. 1  illustrates a perspective view of a section of a plate-fin heat exchanger  100 . Specifically, this figure shows the various components of the heat exchanger  100 , which may include a cold fluid pathway  110 , a hot fluid pathway  120 , cold bars  130 , cold fins  140 , hot bars  150 , hot fins  160 , side plate  170 , and/or tube sheets  180 . In addition,  FIG. 1  shows the hot-cold corner  190  and the hot-hot corner  195  of the heat exchanger  100 . Such a heat exchanger may further include a second side plate (omitted for clarity) at the opposite side of the heat exchanger  100  from the first side plate  170 . 
       FIG. 2  illustrates a perspective view of a section of a plate-fin heat exchanger  200  including porous blocker bars  210  according to an exemplary embodiment of the present invention. The blocker bars may be placed at each inlet and/or outlet to each flow passageway. 
     Such porous blocker bars may provide improved structural integrity, reinforcing the tube sheets  180  and more evenly distributing loads across the passage width of the hot inlet face. In addition, the blocker bars may reduce global and local temperature gradients within the passages of the heat exchanger by increasing local capacitance, thus slowing down metal temperature reaction rates in critical areas. The temperature gradients may also be improved by restricting the amount of hot fluid flow that can enter the passages. 
     As shown in  FIG. 2 , each porous blocker bar  210  may include multiple “pores”  220  (i.e., enclosed passageways or openings that may allow fluid to flow through the porous blocker bar). The pores  220  may be round through-holes oriented along one axis of the blocker bar  210 . In some embodiments, the heat exchanger  200  may be sealed and connected in such a way that the operating parameters of the hot fluid pathway  120  may be determined by the pores  220 . In this manner, the pores may be used to control hot flow through the heat exchanger (e.g., by configuring the pores to have an appropriate size and/or spacing for the desired flow). The porous blocker bars  210  and/or the pores  220  may utilize application-specific configurations, as described in more detail below. 
     The cold fluid pathway  110  may allow cold fluid to pass through the heat exchanger  200  in a first direction (indicated by arrow  110 ). The cold bars  130  may be arranged such that the bars seal the edges of the cold fluid pathway  110  along the direction of flow. The cold fins  140  may be arranged such that the fins allow fluid to flow along the cold fluid pathway  110 . The hot fluid pathway  120  may allow hot fluid to pass through the heat exchanger in a second direction (indicated by arrow  120 ). The hot bars  150  may be arranged such that the bars seal the edges of the hot fluid pathway  120  along the direction of flow. The hot fins  160  may be arranged such that the fins allow fluid to flow along the hot fluid pathway  120 . The side plate (or plates)  170  and tube sheets  180  may be arranged such that the pathways  110 - 120  each allow flow along a single axis. Each fluid pathway may include a number of flow passages (i.e., flow paths at each level of the pathway). 
     Although the pores  220  are represented as round through-holes in the example of  FIG. 2 , one of ordinary skill in the art will recognize that different embodiments may include different pores, as appropriate. For example, some embodiments may include pores that have non-round shapes (e.g., square, triangular, octagonal, etc.) or are otherwise irregularly-shaped (e.g., ellipses, non-symmetrical polygons, etc.). In addition, some embodiments may include different pores (e.g., a single embodiment may include round and non-round pores). Furthermore, some embodiments may include non-uniformly sized pores (e.g., the pores may be sized to be smaller at the ends of the blocker bar and larger near the center of the blocker bar, or vice-versa). 
     The various components of the heat exchanger  200  may be made from various appropriate materials (e.g., steel, aluminum, titanium, etc.) and/or combinations of materials. In addition, the heat exchanger may include different numbers of various components, as appropriate (e.g., based on the size of the heat exchanger, operating temperatures, flow requirements, etc.). Such components may be arranged in various appropriate ways. For example, different embodiments may include different numbers of flow passages. As another example, different embodiments may include different numbers of hot and/or cold bars (and interceding hot and/or cold fins) at each passage. 
       FIG. 3  illustrates a perspective view of the porous blocker bar  210 . As shown, in some embodiments, the blocker bar may have a generally rectangular shape, where the shape may be defined by a width  310 , depth  320 , and height  330 . Different embodiments may utilize different blocker bars, as appropriate (e.g., bars of varying size, shape, etc.). The pores  220  may run from a front face  340  of the blocker bar to a rear face. The front face may be situated to face toward the direction of the hot fluid pathway  120  (i.e., the inlet end of the pathway) while the rear face may be situated to face toward the outlet end of the pathway. In this example, the pores are arranged at constant spacing along the middle of the front face  340 , however, the pores may be arranged in various appropriate ways (e.g., a grid of offset pores, sets of pores at various locations along the face, etc.). 
       FIG. 4  illustrates a top view of a section of the porous blocker bar  210 , specifically highlighting the size  410  and spacing  420  of pores  220  along the porous blocker bar. In this example, the pores run from the front face  340  to the rear face  430 . The size  410  of the pores  220  is defined by a diameter of the through-hole, while the spacing  420  is defined by a distance along a second axis of the blocker bar. Although the pores  220  are shown in this example as having a constant diameter through the entire depth  320  of the blocker bar  210 , different embodiments may have differently-shaped pores (e.g., the pores may taper from a larger diameter at the inlet side of the blocker bar to a smaller diameter at the outlet side of the blocker bar, or vice-versa). 
       FIG. 5  illustrates a flow chart of a conceptual process  500  used in some embodiments to configure various physical parameters of the porous blocker bar  210 . Such application-specific configurations may allow the porous blocker bars to be optimized for use in a variety of heat exchangers that may correspond to a variety of applications. The process may be performed by a system such as the system  600  described below. 
     Process  500  may begin when a user begins design of a porous blocker bar. As shown, the process may receive (at  510 ) dimensional parameters. Such dimensional parameters may include the size and/or shape of the blocker bar, desired pore size, etc. Next, the process may receive (at  520 ) various operating parameters for the blocker bar. Such operating parameters may include minimum and/or maximum flow rates, operating temperatures, etc. In addition, the operating parameters may include various user-desired performance of the heat exchanger (e.g., temperature gradients, heat exchange, operating life, etc.). 
     The process may then evaluate (at  530 ) the parameters received at  510  and  520 . Such evaluation may include comparing the received parameters to various thresholds or tolerances, any limitations of the manufacturing facility, etc. The process may then calculate (at  540 ) various design parameters. Such calculation may involve performing a set of mathematical operations, optimizing results for a particular manufacturing facility, etc. The design parameters may include the size, shape, and/or spacing of pores to be included in the blocker bar. Finally, the process may store (at  550 ) the calculated design parameters and then end. The stored design parameters may then be available for use in designing and manufacturing the blocker bars. 
     Although process  500  has been described with reference to various details, one of ordinary skill in the art will recognize that the process may be performed in various appropriate ways without departing from the spirit of the invention. For instance, the operations of the process may be performed in various different orders. As another example, only a subset of operations may be performed in some embodiments, or the process may be performed as a set of sub-processes. As yet another example, the process may be performed as a sub-process of another process. 
       FIG. 6  illustrates a schematic diagram of a conceptual system  600  used in some embodiments to implement process  500 . As shown, the system  600  may include a bus  610 , one or more processors  620 , one or more input/output devices  630 , one or more storages  640 , and/or one or more network interface(s). The system may be implemented using a variety of specific devices, either alone or in conjunction (e.g., a mobile device, a personal computer, a tablet device, a Smartphone, a server, etc.) and/or a variety of communication pathways, either alone or in conjunction (e.g., physical pathways such as wires and cables, wireless pathways, etc.). 
     The bus  610  conceptually represents all communication pathways available to the system  600 . The processor(s)  620  may include various computing devices (e.g., microprocessors, digital signal processors, application-specific integrated circuits, etc.). The input/output device(s)  630  may include input devices such as mice, keyboards, etc., and/or output devices such as monitors, printers, etc. The storage(s)  640  may include various transitory and/or non-transitory storage(s) (e.g., RAM storage, ROM storage, “cloud” storage, etc.). The network interface(s)  650  may include various circuitry and/or software that allow the system  600  to connect to one or more networks (e.g., a local-area network, a wide-area network, etc.) or one or more networks of networks (e.g., the Internet). 
     System  600  may be used to execute the operations of, for instance, process  500 . In some embodiments, process  500  may be implemented using sets of software instructions. Such sets of software instructions may be stored in storage  640  such that they may be retrieved and executed by processor  620 . In addition, data such as dimensional parameters and/or operating parameters may be stored in storage  640 . Processor  620  may retrieve and use the data when executing the software instructions to evaluate the received parameters and calculate the design parameters. The processor  620  may send the calculated design parameters to the storage  640 . In this manner, the calculated design parameters may be made available to various appropriate manufacturing entities (e.g., the design parameters may be used to generate technical drawings that are supplied to a machine shop that will fabricate the porous blocker bars). 
     It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.