Abstract:
An extruded tube for a heat exchanger is disclosed, the tube including a plurality of deformations formed therein, wherein the deformations of the extruded tube facilitates a maximization of a thermal efficiency of the heat exchanger.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates generally to an extruded tube for use in a heat exchanger, and more particularly to an extruded tube including a plurality of deformations formed on at least one surface thereof for use in a heat exchanger. 
       BACKGROUND OF THE INVENTION 
       [0002]    Heat exchangers are used for changing temperature of various working fluids, such as an engine coolant, an engine lubricating oil, an air conditioning refrigerant, and an automatic transmission fluid, for example. The heat exchanger typically includes a plurality of spaced apart fluid conduits or tubes connected between an inlet tank and an outlet tank, and a plurality of heat exchanging fins disposed between adjacent conduits. Air is directed across the fins of the heat exchanger by a cooling fan or a motion of a vehicle, for example. As the air flows across the fins, heat in a fluid flowing through the tubes is conducted through the walls of the tubes, into the fins, and transferred into the air. 
         [0003]    One of the primary goals in heat exchanger design is to achieve the highest possible thermal efficiency. Thermal efficiency is measured by dividing the amount of heat that is transferred by the heat exchanger under a given set of conditions (amount of air flow, temperature difference between the air and fluid, and the like) by the theoretical maximum possible heat transfer under those conditions. Thus, an increase in the rate of heat transfer under a given set of conditions results in a higher thermal efficiency. 
         [0004]    Typically, to improve thermal efficiency, the air flow must be improved, a pressure drop through the heat exchanger must be reduced, or a surface area of the tubes must be maximized. Prior art attempts to maximize the surface area of the tubes have had a negative affect on pressure drop within the tube, thus decreasing the thermal efficiency of the heat exchanger. 
         [0005]    It would be desirable to produce an extruded tube for a heat exchanger, whereby a thermal efficiency of the heat exchanger is maximized, material usage is minimized, and a durability of the tube is maintained. 
       SUMMARY OF THE INVENTION 
       [0006]    Consistent and consonant with the present invention, an extruded tube for a heat exchanger, whereby a thermal efficiency of the heat exchanger is maximized, material usage is minimized, and a durability of the tube is maintained, has surprisingly been discovered. 
         [0007]    In one embodiment, an extruded tube comprises a top wall, a bottom wall, and a pair of side walls having at least one flow passageway formed therein; at least one web disposed in the flow passageway and extending from at least one of the top wall and the bottom wall; and at least one deformation formed in at least one of the top wall, the bottom wall, and the side walls. 
         [0008]    In another embodiment, an extruded tube for a heat exchanger comprises a top wall, a bottom wall, and a pair of side walls having a plurality of flow passageways formed therein; a web disposed in at least one of the flow passageways and extending from at least one of the top wall and the bottom wall; and a plurality of deformations formed on at least one of the top wall, the bottom wall, and the side walls. 
         [0009]    In another embodiment, an extruded metal tube for a heat exchanger comprises a top wall, a bottom wall, and a pair of side walls having a plurality of flow passageways formed therein; a web disposed in each of the flow passageways and extending from at least one of the top wall and the bottom wall; and a plurality of deformations formed on the top wall, the bottom wall, and the side walls. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The above, as well as other objects and advantages of the invention, will become readily apparent to those skilled in the art from reading the following detailed description of a preferred embodiment of the invention when considered in the light of the accompanying drawings in which: 
           [0011]      FIG. 1  is a perspective view of a heat exchanger in accordance with an embodiment of the invention; 
           [0012]      FIG. 2  is a perspective view of a portion of an extruded tube disposed in the heat exchanger illustrated in  FIG. 1 ; 
           [0013]      FIG. 3  is a perspective view of a portion of an extruded tube in accordance with another embodiment of the invention; 
           [0014]      FIG. 4  is a perspective view of a portion of an extruded tube in accordance with another embodiment of the invention; 
           [0015]      FIG. 5  is a sectional view of an extruded tube in accordance with another embodiment of the invention; and 
           [0016]      FIG. 6  is a sectional view of an extruded tube in accordance with another embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0017]    The following detailed description and appended drawings describe and illustrate various exemplary embodiments of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner. 
         [0018]      FIG. 1  shows a heat exchanger assembly  10  according to an embodiment of the invention. The heat exchanger assembly  10  includes a first manifold  12  and a second manifold  14  disposed on opposing ends thereof. In the embodiment shown, the heat exchanger assembly  10  is a U-flow type heat exchanger assembly. However, it is understood that other types of heat exchanger assemblies can be used such as a serpentine-flow type heat exchanger assembly, a parallel flow type heat exchanger assembly, and a multi-row parallel or counter-flow type heat exchanger assembly, for example. The heat exchanger assembly  10  also includes a plurality of substantially parallel tubes  16  disposed between and in fluid communication with the first manifold  12  and the second manifold  14 . Each of the tubes  16  is connected at a first end  18  to the first manifold  12 , and at a second end  20  to the second manifold  14 . In the embodiment shown, the manifolds  12 ,  14  and the tubes  16  are formed from aluminum. However, any suitable material can be used, as desired. 
         [0019]    The first manifold  12  includes an inlet fitting  22 , a plurality of tube openings (not shown) formed therein for receiving the first ends  18  of the tubes  16 , and an outlet fitting  24 . The inlet fitting  22  is adapted to communicate with a source of coolant (not shown). The tube openings provide fluid communication between the first manifold  12  and the tubes  16 . The outlet fitting  24  provides an exit for the coolant flowing through the heat exchanger assembly  10  and is typically in communication with the source of coolant or other storage system. A baffle (not shown) is sealingly disposed in the first manifold between the inlet fitting  22  and the outlet fitting  24  to create a substantially fluid tight seal therebetween. 
         [0020]    The second manifold  14  includes a plurality of tube openings (not shown) formed therein for receiving the second ends  20  of the tubes  16 . The tube openings provide fluid communication between the tubes  16  and the second manifold  14 . 
         [0021]    As more clearly shown in  FIG. 2 , the tubes  16  are generally rectangular shaped in cross section and include a plurality of flow passageways  26  formed therein. The flow passageways  26  extend longitudinally through the tubes  16  and are divided from one another by a plurality of tube dividers  27 . It is understood that the tubes  16  may have any cross-sectional shape as desired. The tubes  16  have a tube height H defined by a distance between a substantially planar top wall  28  and a substantially planar bottom wall  30 . The tubes  16  also include a tube width W defined by a distance between a first side wall  32  and a second side wall  34 . In the embodiment shown, the side walls  32 ,  34  are generally arcuate in shape, but may have other shapes. The tubes  16  include at least one internal web  36  extending from one or both of the top wall  28  and the bottom wall  30  in each of the flow passageways  26  in the tubes  16 . In the embodiment shown, the webs  36  have a T-shape in cross section or a generally linear cross-sectional shape. It is understood the webs  36  can have other cross-sectional shapes as desired. A tube length (not shown) is defined by a distance between the respective manifolds  12 ,  14 . 
         [0022]    The tubes  16  include a plurality of deformations  38  formed therein. In the embodiment shown, the deformations  38  are formed on the top wall  28  and the bottom wall  30  of the tubes  16 . However, it is understood that the deformations  38  can be formed on only one of the top wall  28  and the bottom wall  30 , and may also be formed on the side walls  32 ,  34  of the tubes  16 . As shown, the deformations  38  are formed as indentations or recesses in exterior surfaces of the top wall  28  and the bottom wall  30  which form corresponding protuberances or ridges on interior surfaces of the top wall  28  and the bottom wall  30 . The deformations  38  are formed on the top wall  28  and the bottom wall  30  in a generally repeating pattern in the embodiment shown, wherein the deformations  38  are formed in alternating flow passageways  26  and are substantially evenly spaced along the length and width W of the tubes  16 . It is understood that other patterns can be formed on the tubes  16  as desired. The deformations  38  cause the webs  36  to protrude toward and abut or nearly abut one another. 
         [0023]    As shown in  FIG. 1 , the tubes  16  are generally evenly spaced and have spaces  40  formed therebetween. A plurality of fins (not shown) may be disposed within the spaces  40  between each adjacent tube  16 . The fins typically have a corrugated shape with a series of convolutes that extend between adjacent tubes  16 , as is known in the art. A series of louvers (not shown) may be provided on each corrugation of the fins to further aid in heat transfer to the air passing therethrough. 
         [0024]    In use, a first fluid (not shown) is caused to flow through the inlet fitting  22  into a first section of the first manifold  12  on a first side of the baffle. The first fluid can be any conventional fluid such as automatic transmission fluid, power steering fluid, or engine oil, for example. The first fluid then flows into the flow passageways  26  of a first set of the tubes  16  through the corresponding tube openings formed in the first section of the first manifold  12 . The first fluid contains thermal energy which is transferred to the interior surfaces of the tubes  16  as the first fluid flows through the flow passageways  26 . A second fluid (not shown) is caused to flow through the spaces  40  between adjacent tubes  16 , and contacts the exterior surfaces of the tubes  16 . The second fluid can be any conventional fluid such as air, for example. The thermal energy transferred to the tubes  16  by the first fluid is transferred to the second fluid as the second fluid contacts the exterior surfaces of the tubes  16 . 
         [0025]    The first fluid then flows into and out of the second manifold  14  in a U-shaped pattern as is known in the art. Upon exiting the second manifold  14 , the first fluid flows through a second set of the tubes  16  corresponding to a second section of the first manifold  12  on a second side of the baffle. The first fluid then enters the second section of the first manifold  12  through the corresponding tube openings formed therein, and out of the first manifold  12  through the outlet fitting  24 . When flowing through the tubes  16  corresponding to the second section of the first manifold  12 , additional heat is transferred from the first fluid to the second fluid as previously described herein. 
         [0026]    The deformations  38  formed in the tubes  16  provide additional surface area for the first fluid to contact within the flow passageways  26  of the tubes  16 . Further, within each of the flow passageways  26 , a fluid boundary layer is caused to detach from the interior surface of the tube  16  at the deformations  38  as the first fluid changes direction. The fluid boundary layer then reestablishes itself and continues to grow downstream of the deformation  38 . The fluid boundary layer is caused to detach repeatedly in a periodic pattern. The periodic detachment of the fluid boundary layer and change in fluid direction maximizes the transfer of thermal energy from the first fluid to the interior surface of the tubes  16  by disrupting a laminar flow pattern of the first fluid. Accordingly, a thermal efficiency of the heat exchanger assembly  10  is maximized. 
         [0027]      FIG. 3  shows a tube  116  according to another embodiment of the invention. The tube  116  is generally rectangular shaped in cross section and includes a plurality of flow passageways  126  extending longitudinally therethrough. The flow passageways  126  are divided from one another by a plurality of tube dividers  127 . It should be appreciated that the tube  116  may have any cross-sectional shape. The tube  116  has a tube height H 2  defined by a distance between a top wall  128  and a bottom wall  130  thereof. The top wall  128  and the bottom wall  130  are generally planar. Additionally, the tube  116  includes a tube width W 2  defined by a distance between a first side wall  132  and a second side wall  134 . In the embodiment shown, the side walls  132 ,  134  are generally planar and have arcuate upper and lower portions  133 ,  135 , but may have any shape. The tube  116  includes at least one internal web  136  extending from at least one of the top wall  128  and the bottom wall  130  in the flow passageways  126 . In the embodiment shown, the webs  136  have a cross-sectional T-shape, but may have other cross-sectional shapes as desired. 
         [0028]    The tube  116  includes a plurality of deformations  138  formed therein. In the embodiment shown, the deformations  138  are formed on the top wall  128  and the bottom wall  130  of the tube  116 . However, it is understood that the deformations  138  can be formed on only one of the top wall  128  and the bottom wall  130 , and may also be formed on the side walls  132 ,  134  of the tubes  16  as desired. The deformations  138  are formed as indentations or recesses in exterior surfaces of the top wall  128  and the bottom wall  130 , and corresponding protuberances on interior surfaces of the top wall  128  and the bottom wall  130 . The deformations  138  are formed on the top wall  128  and the bottom wall  130  in generally repeating patterns in the embodiment shown, wherein the deformations  138  are formed in adjacent flow passageways  126  and are substantially evenly spaced apart along the length and width W 2  of the tube  116 . It is understood that other patterns of deformations  138  can be formed on the tube  116  as desired, such as a random pattern, for example. The deformations  138  cause the webs  136  to protrude toward and abut or nearly abut one another. 
         [0029]    Use of the tube  116  is substantially the same as previously described herein for the tube  16 . Similarly, the deformations  138  formed on the tubes  116  provide for additional surface area for thermal energy transferred from the first fluid to the tubes  116 . Accordingly, a thermal efficiency of the heat exchanger assembly  10  is maximized. 
         [0030]      FIG. 4  shows a tube  216  according to another embodiment of the invention. The tube  216  is generally rectangular shaped in cross section and includes a plurality of flow passageways  226  extending longitudinally therethrough. It should be appreciated that the tube  216  may have any cross-sectional shape. The tube  216  has a tube height H 3  defined by a distance between a top wall  228  and a bottom wall  230  thereof. The top wall  228  and the bottom wall  230  are generally planar. Additionally, the tube  216  includes a tube width W 3  defined by a distance between a first side wall  232  and a second side wall  234 . In the embodiment shown, the side walls  232 ,  234  are generally planar and have arcuate upper and lower portions  233 ,  235 , but may have any suitable shape. The tube  216  includes at least one internal web  236  extending from at least one of the top wall  228  and the bottom wall  230  to divide the flow passageways  226  in the tube  216 . In the embodiment shown, the webs  236  have a cross-sectional T-shape, but may have other cross-sectional shapes as desired. 
         [0031]    The tube  216  includes a plurality of deformations  238  formed therein. In the embodiment shown, the deformations  238  are formed on the top wall  228 , the bottom wall  230 , and the arcuate upper and lower portions  233 ,  235  of the side walls  232 ,  234  of the tube  216 . The deformations  238  are formed as indentations or recesses in exterior surfaces of the top wall  228 , the bottom wall  230 , and the arcuate upper and lower portions  233 ,  235  and corresponding protuberances on interior surfaces of the top wall  228 , the bottom wall  230 , and the arcuate shaped upper and lower portions  233 ,  235 . The deformations  238  are formed on the top wall  228 , the bottom wall  230 , and the arcuate shaped upper and lower portions  233 ,  235  of the side walls  232 ,  234  in generally repeating patterns in the embodiment shown, wherein the deformations  238  are formed in adjacent flow passageways  226  and on the arcuate shaped upper and lower portions  233 ,  235  of the side walls  232 ,  234 , and are substantially evenly spaced apart along the length and width W 3  of the tube  216 . It is understood that other patterns of deformations  238  can be formed on the tube  216  as desired, such as a random pattern, for example. The deformations  238  cause the webs  236  to protrude toward and abut or nearly abut the interior surface of the tube  216 . 
         [0032]    Use of the tube  216  is substantially the same as previously described herein for the tube  16 . Similarly, the deformations  238  formed on the tubes  216  provide for additional surface area for thermal energy transferred from the first fluid to the tubes  216 . Accordingly, a thermal efficiency of the heat exchanger assembly  10  is maximized. 
         [0033]      FIG. 5  shows a tube  316  according to another embodiment of the invention. The tube  316  is generally rectangular shaped in cross section and includes a plurality of flow passageways  326  extending longitudinally therethrough. The flow passageways  326  are divided from one another by a plurality of tube dividers  327 . It should be appreciated that the tube  316  may have any suitable cross-sectional shape. The tube  316  has a tube height H 4  defined by a distance between a top wall  328  and a bottom wall  330  thereof. The top wall  328  and the bottom wall  330  are generally planar. Additionally, the tube  316  includes a tube width W 4  defined by a distance between a first side wall  332  and a second side wall  334 . In the embodiment shown, the side walls  332 ,  334  are generally arcuate, but may have any shape as desired. The tube  316  includes at least one internal web  336  extending from at least one of the top wall  328  and the bottom wall  330  in each of the flow passageways  326 . The webs  336  have one of a T-shaped cross-sectional shape or a linear cross-sectional shape, but may have other cross-sectional shapes as desired. 
         [0034]    The tube  316  includes a plurality of deformations  338  formed thereon. In the embodiment shown, the deformations  338  are formed on the top wall  328  of the tube  316 . However, it is understood that the deformations  338  can be formed on the bottom wall  330  and the side walls  332 ,  334  of the tube  316  as desired. The deformations  338  are formed as indentations or recesses in an exterior surface of the top wall  328  and corresponding protuberances on an interior surface of the top wall  328 . The deformations  338  are formed on the top wall  328  in a generally repeating pattern in the embodiment shown, wherein the deformations  338  are formed in alternating flow passageways  326 , and are substantially evenly spaced apart along the length and width W 4  of the tube  316 . It is understood that other patterns of deformations  338  can be formed on the tube  316  as desired, such as a random pattern, for example. The deformations  338  cause the webs  336  to protrude toward and abut or nearly abut one another. 
         [0035]    Use of the tube  316  is substantially the same as previously described herein for the tube  16 . Similarly, the deformations  338  formed on the tubes  316  provide for additional surface area for thermal energy transferred from the first fluid to the tubes  316 . Accordingly, a thermal efficiency of the heat exchanger assembly  10  is maximized. 
         [0036]      FIG. 6  shows a tube  416  according to another embodiment of the invention. The tube  416  is generally rectangular shaped in cross section and includes a flow passageway  426  extending longitudinally therethrough. It should be appreciated that the tube  416  may have any cross-sectional shape. The tube  416  has a tube height H 5  defined by a distance between a top wall  428  and a bottom wall  430  thereof. The top wall  428  and the bottom wall  430  are generally planar. Additionally, the tube  416  includes a tube width W 5  defined by a distance between a first side wall  432  and a second side wall  434 . In the embodiment shown, the side walls  432 ,  434  are generally planar and have arcuate upper and lower portions  433 ,  435 , but may have any suitable shape. The tube  416  includes at least one internal web  436  extending from at least one of the top wall  428  and the bottom wall  430 . The webs  436  have a T-shaped cross section, but may have other cross-sectional shapes as desired. 
         [0037]    The tube  416  includes a plurality of deformations  438  formed therein. In the embodiment shown, the deformations  438  are formed in the top wall  428  of the tube  416 . However, it is understood that the deformations  438  can be formed in the bottom wall  430  and the side walls  332 ,  334  as desired. The deformations  438  are formed as indentations or recesses in an exterior surface of the top wall  428  and corresponding protuberances on an interior surface of the top wall  428 . The deformations  438  are formed in the top wall  428  in a generally repeating pattern in the embodiment shown, wherein the deformations  438  are formed in the flow passageway  426  and are substantially evenly spaced along the length and width W 5  of the tube  416 . It is understood that other patterns of deformations  438  can be formed in the tube  416  as desired such as a random pattern, for example. The deformations  438  cause the webs  436  to protrude toward and abut or nearly abut the interior surface of the tube  416 . 
         [0038]    Used of the tube  416  is substantially the same as previously described herein for the tube  16 . Similarly, the deformations  438  formed on the tubes  416  provide for additional surface area for thermal energy transferred from the first fluid to the tubes  416 . Accordingly, a thermal efficiency of the heat exchanger assembly  10  is maximized. 
         [0039]    From the foregoing description, one ordinarily skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications to the invention to adapt it to various usages and conditions.