Patent Publication Number: US-7896064-B2

Title: Plate-type heat exchanger

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to heat exchangers and more particularly to plate-type heat exchangers. 
     BACKGROUND OF THE INVENTION 
     At least some conventional heat exchangers may be classified into two categories, tubular exchangers and plate exchangers. The conventional plate heat exchangers are manufactured by stacking a plurality of plates, configured in a way so that two fluids, one relatively hot and the other relatively cold, may be passed between alternating channels defined by the plates. 
     Plate heat exchangers may be broken down into two categories, namely gasket containing heat exchangers and welded heat exchangers. Gasketed exchangers can provide accessibility of plates for cleaning, lower thermal stresses, and cost per area. However, some gasket limitations may occur with temperature, pressure and compatibility with fluids used. One problem encountered with existing welded heat exchanger units is the high thermal stresses present which can lead to shorter equipment life. High manufacturing cost of separating the relatively hot and relative cold fluid via common welding procedures is another potential disadvantage. 
     SUMMARY OF THE INVENTION 
     A heat exchanger may include a housing and a core having a shell. The shell may have an upper wall, a lower wall, and a pair of opposed side walls interconnecting the upper and lower walls to define at least part of an enclosure in which a fluid may be received. The housing may have an upper plate adjacent to the upper wall, a lower plate adjacent to the lower wall and a pair of side plates each adjacent to a separate one of the side walls. The upper plate may be connected to the lower plate and the side plates may be connected together to support the upper wall, lower wall and side walls of the shell. The support provided by the housing may, in at least some applications, permit use of a lower strength and less expensive shell. 
     In one presently preferred implementation, the heat exchanger core includes upper and lower walls and a pair of side walls interconnecting the upper and lower walls, and the housing surrounds at least a portion of each of the top and bottom walls and the side walls. The housing may be made of a plurality of plates releasably connected together to permit access to the core, as desired. This implementation allows the walls to be manufactured via flame cutting instead of traditional machining. Of course, other implementations, modifications and/or substitutions may be utilized as desired for a particular application. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects, features, and advantages of the present invention will be apparent from the following detailed description of preferred embodiments and best mode, appended claims, and accompanying drawings in which: 
         FIG. 1  is a perspective view of one presently preferred embodiment of a heat exchanger; 
         FIG. 2  is a plan view of the heat exchanger of  FIG. 1 ; 
         FIG. 3  is a side view of the heat exchanger of  FIG. 1 ; 
         FIG. 4  is an end view of the heat exchanger; 
         FIG. 5  is a perspective view of a welded plate heat exchanger core which may be used in the assembly shown in  FIG. 1 ; and 
         FIG. 6  is a fragmentary perspective sectional view of the core of  FIG. 5  showing a portion of plates within the interior of the core. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring in more detail to the drawings,  FIGS. 1-4  illustrate one exemplary embodiment of a heat exchanger  10  including an outer support housing  12  and an inner core  14 . The heat exchanger  10  is shown as a plate heat exchanger having a basically rectangular core  14 , although other shapes and configurations are possible. It is the intention of the drawings and this description to show exemplary embodiments of the invention and in no way limit the construction, arrangement, or method in which the invention is embodied. 
     As best shown in  FIG. 5 , the core  14  includes an outer shell  16  consisting of a primary inlet header  18 , a primary outlet header  20 , a secondary inlet header  22  forming a portion or all of one sidewall  24  of the shell  16 , a secondary outlet header  26  forming a portion or all of another sidewall  28  of the shell, a top wall  30 , and a bottom wall  32 . The headers  18 ,  20 ,  22 ,  26 , and the walls  30 ,  32  are interconnected to enclose a plate assembly  31  a portion of which is shown in  FIG. 6 . The headers  18 ,  20 ,  22 ,  26  and the walls  30 ,  32  may be welded together to define an at least substantially complete enclosure. The secondary inlet and outlet headers  22  and  26  and the walls  30 ,  32  may be generally flat plates providing a generally box shaped or rectangular parallelepiped shaped shell  16 . 
     As best shown in  FIG. 6 , the internal arrangement and construction of the core  14 , including the plate assembly  31 , can be substantially as disclosed in U.S. Pat. No. 6,516,874, the disclosure of which is incorporated herein by reference in its entirety. In general, located within the shell  16  are a plurality of cassettes, each identified by reference numeral  34  that form a part of the plate pack assembly  31 . Each cassette  34  is constructed from two rectangular heat transfer plates  36  and  36   a  the central body portion of each of which is formed with a plurality of parallel and angled corrugations or depressions. In forming a cassette  34 , one of the heat transfer plates  36 ,  36   a  is rotated 180 degrees and turned over so that one of the plates is superimposed upon the other. As seen in  FIG. 6 , this causes the corrugations of each of the heat transfer plates  36 ,  36   a  to cross each other at a fixed angle and provide plurality of parallel and angled outer ridges  38  and inner ridges  40  for each of the heat transfer plates  33 ,  33   a.    
     As seen in  FIGS. 5 and 6 , the cassettes  34  within the core of the heat exchanger  10  provide primary channels  42  for the flow of a primary fluid and secondary channels  44  for the flow of a secondary fluid. The primary fluid enters the heat exchanger  10  through a primary inlet nozzle  45  which is rigidly connected to an arcuately shaped inlet header  18 . The primary fluid exits through a primary outlet nozzle  46  which is rigidly connected to the arcuately shaped outlet header  20 . Accordingly, primary fluid entering the heat exchanger  10  via the primary inlet nozzle  45 , flows through the primary channels  42 , and exits the heat exchanger  10  through the primary outlet nozzle  46 . The secondary fluid enters the heat exchanger  10  via the secondary inlet nozzle  47 , flows through the secondary channels  44 , and exits through the secondary outlet nozzle  48 . As should be apparent, the inlet nozzle  47  and the outlet nozzle  48  are rigidly connected to the secondary inlet header  22  and the secondary outlet header  26 , respectively. 
     As shown in  FIGS. 1-4 , the support housing  12  includes opposed upper and lower plates,  52 ,  54  and a pair of opposed side plates  56 ,  58  all arranged in close proximity to the outer surface of the shell  16  of the core  14 . The plates  52 - 58  preferably are connected together and are rigid so that the support housing  12  is rigid and resists deformation in assembly and can support at least portions of the shell  16  against undue expansion. The housing  12  preferably supports at least a portion of three sides of the shell  16 , and preferably a substantial portion (e.g. more than half the surface area) of three or more sides of the shell  16 . This may permit the core shell  16  to be formed of thinner, or less robust material. In at least some embodiments, this can reduce the cost of the heat exchanger assembly because, for example, the shell material which is in contact with fluid typically is formed from a relatively expensive material such as stainless steel, and less of that material may be needed. The support housing  12 , on the other hand, does not contact the fluid and can be formed of less expensive carbon steel. Further, a reduction in machining and welding can be realized, and the support plates  52 - 58  can be flame cut (or otherwise) and relatively unfinished thereby further reducing the cost to manufacture and assembly the heat exchanger  10 . 
     The opposed pair of upper and lower plates  52 ,  54  and opposed pair of side plates  56 ,  58  may be connected together to define an at least substantially complete enclosure in which the core  14  is received. In one presently preferred implementation, a plurality of connection features  60  are used to releasably connect adjacent plates together so that the housing  12  may be taken apart and the core  14  removed for repair or replacement with a new core. In the implementation shown, the connection features  60  include fingers spaced along the plates  52 - 58  and connectors  64  that connect together the fingers of adjacent plates. Due to the relatively high number of fingers and connectors in the particular embodiment shown in the drawings, not all of these parts have been labeled on the drawings. Rather, to facilitate viewing and understanding the drawings, only a representative number of such parts have been labeled on the drawings. 
     More specifically, as best shown in  FIGS. 1-3 , the upper and lower plates  52 ,  54  may be of identical construction. The plates  52 ,  54  may be generally planar with fingers  66  that are spaced apart and extend outwardly from opposed sides of each plate  52 ,  54 . The fingers  66  on one side of a plate extend away from the fingers  66  on the other side of that plate, and the plates  52 ,  54  preferably may be arranged so that the fingers  66  on the upper plate  52  are aligned with the fingers  66  of the lower plate  54 . Each finger  66  preferably has at least one opening  68  therethrough. The openings  68  in aligned fingers  66  of the upper and lower plates  52 ,  54  are aligned to receive a connector  64  therethrough so that the aligned fingers  66  can be connected together. As shown, the connector  64  may include a rod  70  having threaded ends  72  and nuts  74  may be tightened on each end  72  of the rod  70 . 
     The side plates  56 ,  58  may be identical and are preferably arranged similarly to the upper and lower plates  52 ,  54  but are located adjacent to the sidewalls  24 ,  28  of the core  14 . The side plates  56 ,  58  include outwardly extending fingers  76  with the fingers  76  on one side plate  56  aligned with the fingers  76  on the other side plate  58 . The fingers  76  of the side plates  56 ,  58  also preferably include at least one opening  78  therethrough with the openings  78  in the fingers  76  of one side plate  56  aligned with the openings  78  in respective fingers  76  of the other side plate  58  to facilitate connecting the fingers  76  of the side plates  56 ,  58  together. The fingers  76  of the side plates  56 ,  58  preferably are received in the gaps between and interspersed with adjacent fingers  66  of the upper and lower plates  52 ,  54 . The fingers  76  of the side plates  56 ,  58  may extend at right angles to the fingers  66  of the upper and lower plates  52 ,  54 . Rods  70  may extend through the openings  78  of aligned fingers  76  of the side plates  56 ,  58  and nuts  74  preferably are tightened on each end  72  of the rods  70 . 
     In this manner, the connectors  64  clamp aligned fingers  66  of the upper and lower plates  52 ,  54  together and against associated walls or surfaces of the core. Likewise, connectors  64  clamp aligned fingers  76  of the side plates  56 ,  58  together and against associated walls of the core. In one presently preferred implementation, the side plates  56 ,  58  do not touch the upper and lower plates  52 ,  54 . A one-quarter inch tolerance may be provided at all plate to plate interfaces so that the clamping force is applied to the shell, not the adjacent panels. By way of one alternate example, the plates  52 ,  54 ,  56 , and  58  may engage each other and be received closely adjacent to the core to prevent undue expansion of or stresses in the core. 
     So all of the plates  52 - 58  are connected together, and may be disconnected by removing the nuts  74  to permit access to the core  14 . The rods  70  connecting together the side plates  56 ,  58  may extend parallel to and outboard of the upper and lower plates  52 ,  54 . The rods  70  connecting together the upper and lower plates  52 ,  54  may extend parallel to and outboard of the side plates  56 ,  58 . The ends  80 ,  82  of the housing  12  may be open to permit one or more inlets  45  and outlets  46  to extend therethrough for connection to suitable conduits or the like. Otherwise one or all of the ends  80 ,  82  could be overlied and supported by separate plates or by portions of the upper, lower or side plates that extend adjacent to the ends. Therefore, the support housing  12  in the implementation shown provides rigid support to four sides of the core  14 . Support may be provided to more or fewer sides, as desired for a particular application, and provision, such as openings through one or more of the plates of the support housing, can be made for the inlets and outlets, or otherwise, as needed. 
     The support housing  12  may be received on one or more brackets  90  to facilitate connecting the heat exchanger  10  to and space it from another structure. The brackets  90  may include outwardly extending feet  92  and preferably are spaced along the length of the heat exchanger  10 . 
     The above description of certain embodiments of the invention is merely exemplary in nature and, thus, variations, modifications and/or substitutions thereof are not to be regarded as a departure from the spirit and scope of the invention. By way of example without limitation, while the support housing  12  in the exemplary embodiment shown and described may be disassembled and removed from the core  14 , the support housing  12  could be welded or otherwise more or less permanently assembled providing limited or no access to the core  14 . Further, while shown and described as including metal plates, a portion or all of the support housing  12  may be formed of other materials, as desired for a particular application. An apparatus or assembly embodying the present invention may have none, some, or all of the noted features and/or advantages. That certain features are included in the presently preferred embodiments set forth herein should not be constructed to mean that all embodiments of the present invention must have such features.