Abstract:
A heat exchanger, such as a radiator, may transfer heat from a liquid and employ a first header tank, a second header tank, a plurality of tubes fluidly joining the first and second header tanks, and a baffle within one of the first or second header tanks. The baffle may be located in a header tank positioned substantially parallel or perpendicular to a surface upon which a vehicle employing the hear exchanger rests. The baffle may be a wall defining only one slot, a wall defining only one slot that is open through one side of the wall, a wall that defines a plurality of slots, or a wall that defines a plurality of holes. The heat exchanger may further employ fluidly isolated first and second tube and fin sections each defining a self-contained flow path for cooling different liquids. The baffle may slow coolant flow in a flow path.

Description:
FIELD 
     The present disclosure relates to a baffle within a heat exchanger. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. With reference to  FIG. 1 , current vehicles may employ one or more heat exchangers  2 ,  4 , such as radiator  2  and condenser  4 , to cool liquids that are continuously circulated through heat generating devices on the vehicle. Regarding a radiator  2 , liquid coolant may first be passed through an internal combustion engine before the coolant is circulated through radiator  2  to be cooled. Similarly, a vehicle air-conditioning system may compress a refrigerant that is then cooled by being passed through condenser  4 . Airflow  6  and a fan  8  may assist in delivering air through each of radiator  2  and condenser  4 . A shroud  10  may further assist in directing airflow. However, such an arrangement may be subject to improvement. For instance, when heated liquids are introduced into a heat exchanger, thermal strain may develop at specific locations of the heat exchanger. Area  12  depicts an area of radiator  2  that is blocked by airflow  6  and thus may experience thermal strain. Thermal strain occurs during expansion and contraction created during heating and cooling of the material that forms the rigid and connected coolant channels of heat exchanger  2 . The rate at which heating and cooling occurs depends upon the temperature, flow rate and quantity of heat of incoming liquid supplied into and through material of heat exchanger  2  relative to the temperature and rate of change of the temperature of material of the heat exchanger at the location at which the incoming liquid is received. 
       FIG. 2  depicts a cross-flow heat exchanger  16  that exhibits thermal strain within a material of heat exchanger  16 . More specifically, a liquid  18  flows into inlet  14  and horizontally across a bottom portion  20  of heat exchanger  16  before flowing into a top portion  22  of heat exchanger  16  and out outlet  17 . Liquid  18  flow transitions from flowing horizontally across bottom portion  20  to top portion  22  at header tank  26 . Because liquid  18  cools while passing across and through a bottom portion  20  and also while passing across a top portion  22 , thermal strain may occur at the juncture or adjacent portions of bottom portion  20  and top portion  22 . As an example, at area  28  is a location that experiences simultaneous contact with the highest temperature of liquid  18  and the lowest temperature of liquid  24 .  FIG. 2  also graphically presents a representative heat differential within heat exchanger  16 . With mean temperature increasing from left to right on temperature distribution graph  30 , one may see that the mean temperature  32  of liquid  18  in bottom portion  20  is higher than the mean temperature  34  of liquid  24  in top portion  22 . Thus, across a juncture of lower portion  20  and upper portion  22 , such as at area  28 , greatest expansion and contraction of the material of heat exchanger  16  may occur. Such a heat differential may cause cracks and hasten leaks from heat exchanger  16 . What is needed then is a structure and method for controlling thermal strain on a heat exchanger. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. A heat exchanger for transferring heat from a liquid may employ a first header tank, a second header tank, a plurality of tubes fluidly joining the first header tank and the second header tank, and a baffle within one of the first header tank and the second header tank. 
     In another arrangement, a heat exchanger for transferring heat from a liquid may employ a first header tank, a second header tank, a plurality of tubes fluidly joining the first header tank and the second header tank, and a baffle within one of the first header tank and the second header tank. The heat exchanger may further employ a first tube and fin section defining a first flow path for cooling a first liquid, and a second tube and fin section defining a second flow path for cooling a second liquid, wherein the first and second tube and fin sections are fluidly isolated from each other and the baffle slows coolant flow in the first tube and fin section. The heat exchanger may be a radiator within a vehicle, such as an automobile, and the baffle may be located in a header tank positioned substantially parallel to a surface of ground upon which the vehicle rests. The heat exchanger may be a radiator within a vehicle and the baffle may be located in a header tank positioned substantially perpendicular to a surface of ground upon which the vehicle rests. The baffle may be a wall that defines only one slot, or the baffle may be a wall that defines only one slot that is open through one side of the wall. Still yet, the baffle may be a wall that defines a plurality of slots that are open through a same side of the wall or the baffle may be a wall that defines a plurality of holes. 
     A heat exchanger for transferring heat from a liquid may employ a first header tank, a second header tank, a plurality of tubes fluidly joining the first header tank and the second header tank, and a baffle within one of the first header tank and the second header tank. The heat exchanger may further employ a first tube and fin section defining a first flow path for cooling a first liquid, and a second tube and fin section defining a second flow path for cooling a second liquid, wherein the first and second tube and fin sections are fluidly isolated from each other and the baffle slows coolant flow in the first tube and fin section. The heat exchanger may be a radiator within a vehicle and the baffle may be located in a header tank positioned substantially parallel or perpendicular to a surface of ground upon which the vehicle rests. The baffle may be a wall that defines only one slot, a wall that defines a single through hole through the wall to permit passage of fluid or a wall that defines a plurality of slots that may be open through a same side of the wall. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a top view of a heat exchanger with a condenser situated in front of the heat exchanger according to the prior art; 
         FIG. 2  is a diagram of a cross-flow heat exchanger and associated heat exchanger according to the prior art; 
         FIG. 3  is a side view of a vehicle depicting the location of an engine and heat exchanger in accordance with the present disclosure; 
         FIG. 4  is a front view of a heat exchanger depicting a location of an interior baffle in accordance with the present disclosure; 
         FIG. 5  is a perspective view of a tube and fin arrangement in accordance with the present disclosure; 
         FIG. 6  is a perspective interior view of a radiator header tank depicting a location of an interior baffle in accordance with the present disclosure; 
         FIG. 7  is a perspective view of an interior of a header tank depicting an interior baffle in accordance with the present disclosure; 
         FIG. 8  is a perspective view of an interior of a header tank depicting an interior baffle in accordance with the present disclosure; 
         FIG. 9  is a perspective view of an interior of a header tank depicting an interior baffle in accordance with the present disclosure; 
         FIG. 10  is a diagram of a cross-flow heat exchanger and associated temperature distribution in accordance with the present disclosure; and 
         FIG. 11  is a perspective view of a multi-cooler heat exchanger equipped with a baffle in accordance with the present disclosure. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to  FIGS. 3-11  of the accompanying drawings. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. Beginning with  FIG. 3 , a vehicle  50 , such as an automobile for example, may be equipped with a device such as an engine  52  and a heat exchanger  54 , which may be a radiator for cooling a liquid coolant that flows through engine  52  and heat exchanger  54 . It should be understood that the teachings of the present disclosure may be applicable to many different types of heat exchangers, whether such heat exchangers are made of metal or plastic. Examples of heat exchangers to which the present disclosure may be applicable to include transmission cooler heat exchangers, such as those used to cool transmission fluid of another device such as an automatic transmission, heater core heat exchangers, such as those used to transfer heat to a passenger compartment of a vehicle, and heat exchangers employed in another device such as vehicle air conditioning systems. Heat exchangers employed in vehicle air conditioning systems include a condenser and an evaporator, both of which are employed to reduce the temperature of an internal refrigerant, whether in a liquid or gaseous phase, or both. 
     Turning now to  FIG. 4 , heat exchanger  54  may have an upper tank  56  and a lower tank  58 , both also known as header tanks, a fluid inlet  60  in upper tank  56  and a fluid outlet  62  in lower tank  58 . Heat exchanger  54  in some aspects may be similar to existing heat exchangers. For instance, as depicted in  FIG. 5 , heat exchanger  54  may be equipped with metal or plastic hollow tubes  66 , arranged in a parallel fashion, such as horizontally or vertically for example, through which a coolant in either a liquid or gaseous phase may flow. Hollow tubes  66  may then be connected to each other with a corrugated, relatively thin metal or plastic fin  68 . As an example, fins  68  may be made of aluminum and conduct or transfer heat from tubes  66 . Heat transferred to fins  68  may then again be transferred to air  71  that flows over exterior surfaces of fins  68  as air  71  flows through a core portion  70 ,  94  of heat exchanger  54 . Core portions  70 ,  94  may employ tubes  66  and fins  68  and may be considered part of core portions  70 ,  94 . Generally, throughout the description, tube and fin portions may collectively be considered a core portion. Continuing,  FIG. 4  depicts vertically arranged tubes  66  of core portion  70 ; however, tubes  66  of core portion  70  may also be arranged horizontally. Tubes  66  arranged horizontally and vertically are determined to be oriented as such relative to a surface upon which vehicle  50  may be parked when tubes  66  are resident in heat exchanger  54  when heat exchanger  54  is used as a radiator of engine  52 , for example. Heat exchanger  54  may also be equipped with an internal baffle  64  in a header tank, such as upper tank  56 . Baffles in header tanks, will now be explained in greater detail. 
       FIG. 4  depicts a location of baffle  64 , which may be located at any position along a longitudinal length of any header tank  56 ,  58 , for example, of heater exchanger  54 .  FIGS. 6 and 7  depict header tank  56  removed from core portion  70 ,  94  of heat exchanger  54  and reveal an internal surface  72 , which may be curved or concave. Header tank  56 , which may be an upper header tank, may be equipped with an internal baffle  64 , which may be a wall  74  having two flat, parallel sides or surfaces, for example. Continuing, wall  74  may have only a single slot  76 , acting as a communication portion, in it to permit the flow of liquid from one side of wall  74  to another side of wall  74 , that is between a chamber on each side of wall  74 . More specifically, slot  76  may permit liquid coolant  78  to pass from chamber  80  to chamber  82  of header tank  56 . Wall  74  with slot  76  will reduce the volume flow rate (volume of liquid per unit time) of liquid coolant that is able to enter chamber  82  of header tank  56  as compared to a structure in which baffle  64  is absent. By reducing the volume flow rate of liquid coolant  78  entering chamber  82 , the quantity of heat entering chamber  82  will also be reduced. With reference again to  FIG. 4 , when header tank  56  is installed as part of heat exchanger  54 , baffle  64  may be located anywhere along header tank  56  depending upon the particular mechanical design of a heat exchanger, including the number of tubes, orientation of tubes, number of liquids cooled by the heat exchanger, etc. The heat transfer characteristics as revealed by a heat transfer analysis using finite element analysis (“FEA”) on the particular mechanical design may also dictate a particular location of baffle  64  within header tank  54 . Regarding  FIG. 4 , core portion  70  of heat exchanger  54  has vertically oriented tubes  66 , and thus, liquid coolant generally flows downward from upper tank  56  to lower tank  58  in a vertical fashion as indicated with arrow  84 . 
       FIG. 8  depicts another embodiment. Baffle  86  is similar to baffle  64  in that a wall  88  having parallel and flat surfaces may have multiple through slots  90 , acting as a communication portion, passing entirely though a thickness dimension of wall  88  and through an edge or side of wall  88 . A complete longitudinal edge or longitudinal surface  92 , which may span between opposing longitudinal sides of upper tank  56 , of wall  88  may abut against an end of tubes  66  so that flowing liquid flowing in upper tank from chamber  80  to chamber  82  must flow through slots  90 , which may be considered a through slot  90  because such slot passes completely through a side and peripheral edge of wall  88  and slots  90  are not completely surrounded by material of wall  88 . Because the cross-sectional area of slots  90  within wall  88  presents less area for liquid coolant to pass through than if wall  88  were not in place, the volume of liquid flowing from chamber  80  to chamber  82  of upper tank  56  may be reduced. Because the flow rate of liquid flowing into chamber  82  is reduced, the quantity of heat in the liquid is reduced, and thus, the temperature of the radiator tubes and fins beyond and below baffle  86 , for example, may be reduced. “Beyond” baffle  86  means the volume of space that is chamber  82 . Below baffle  86  means the volume of space that is below chamber  82 , relative to when heat exchanger  54  is installed in vehicle  10  that is parked on a level surface. For instance, with reference again to  FIG. 4 , “beyond and below” baffle  64  or baffle  86 , depending upon which particular baffle is installed, is indicated as area  94 . The area beyond and below a baffle within a header tank may change as the location of the baffle changes in a top-mounted header tank, such as header tank  56 . 
       FIG. 9  depicts another embodiment. Baffle  95  is similar to baffles  64 ,  86  in that a wall  88  having parallel and flat surfaces may have through holes  96 , acting as communication portions, passing entirely though a thickness dimension of wall  98 . A longitudinal surface or longitudinal edge  100  of wall  98  may abut against an end of tubes  66  so that flowing liquid flowing in upper tank from chamber  80  to chamber  82  must flow through holes  96 . Because the cross-sectional area of holes  96  within wall  98  presents less area for liquid coolant to pass through than if wall  98  were not in place at all, the volume of liquid flowing from chamber  80  to chamber  82  of upper tank  56  is reduced. Because the flow rate of liquid flowing into chamber  82  is reduced, compared to if wall  98  were not in place at all, the quantity of heat passing to chamber  82  is reduced, and thus, the temperature of the radiator tubes and fins beyond and below baffle  95 , for example, may be reduced, as explained above. 
     Turning now to  FIG. 10 , a cross-flow heat exchanger  102  is depicted in which baffle  64 ,  86 ,  95  may be resident within end tank  104 . Because heat exchanger  102  is a cross-flow heat exchanger, liquid coolant flows horizontally through tube and fin portions  108 ,  110 ,  112  between end tanks  104 ,  106 . More specifically, liquid coolant may enter cross-flow heat exchanger  102  at an inlet  114  located near a bottom of end tank  104 . Upon entering, some liquid coolant  109  will begin to flow horizontally through tube and fin portion  108  while some liquid coolant  111  will continue to flow vertically through end tank  104 , through an internal baffle within end tank  104 , and then horizontally through tube and fin portion  110 . Baffle within end tank  104  may be any of baffles  64 ,  86 ,  95  previously presented, for example. Tube and fin portions  108 ,  110 ,  112  may be of a similar construction to tubes  66  and fins  68  explained in conjunction with  FIG. 5 , although oriented with tubes  66  horizontally instead of vertically. 
     Continuing, baffle  64 ,  86 ,  95  may restrict the flow of fluid through end tank  104  and thus also restrict the quantity of heat (i.e. heat rate) resulting in a temperature of liquid coolant  113  within tube and fin portion  110  that is less than that of tube and fin portion  108 . Upon liquid coolant flowing through tube and fin portions  108 ,  110 , liquid coolant flows vertically again within end tank  106  at an opposite end of cross-flow heat exchanger  102  as end tank  104 . Tube and fin portion  112  then receives liquid coolant  115  from end tank  106 . Tube and fin portion  112  may be the uppermost tube and fin portion of cross-flow heat exchanger  102 . Upon flowing through tube and fin portion  112 , liquid coolant  115  then exits cross-flow heat exchanger  102  at outlet  103 . 
     Temperature distribution graph  116  of  FIG. 10  graphically depicts a representative temperature distribution through cross-flow heat exchanger  102 . More specifically, at any given time of steady state flow, at tube and fin portion  108  the material of the cross-flow heat exchanger  102  may be at a mean temperature  118 , at tube and fin portion  110  the material of the cross-flow heat exchanger  102  may be at a mean temperature  120 , and at tube and fin portion  112  the material of the cross-flow heat exchanger  102  may be at a mean temperature  122 . As depicted, and considering that temperature distribution graph  116  is to the same scale as temperature distribution graph  30  of  FIG. 2 , and that heat exchangers  16 ,  102  are the same overall dimensions and specifications, except for the directional flow characteristics and baffle  64 ,  86 ,  95 , area  124  represents less of a temperature variation than area  28  of  FIG. 2 , thus illustrating an advantage of the present disclosure. Stated differently, with less of a temperature variation between tube and fin portion  110  and tube and fin portion  112  of  FIG. 10 , mechanical strain on the material of the cross-flow heat exchanger  102  is less than that of area  28  of  FIG. 2 . 
       FIG. 11  depicts a multi-cooler heat exchanger  126  to which an internal baffle within a header tank may be applied. More specifically, multi-cooler heat exchanger  126  may be equipped with a header tank  128  and a header tank  130 , either of which may contain a baffle such as any of baffles  64 ,  86 ,  95  as explained above in area  132 . Multi-cooler heat exchanger  126  is one overall structure with separate internal, and fluidly separate cooling locations such that two different liquids may be separately cooled at the same time, yet not experience any mixing between the two liquids. More specifically, multi-cooler heat exchanger  126  may be equipped with tube and fin section  134  and tube and fin section  136  that each may contain a different fluid to cool. For instance, tube and fin section  134  may contain a liquid engine coolant while tube and fin section  136  may contain a liquid transmission coolant. Regardless of what devices tube and fin sections  134 ,  136  cool, header tanks  128 ,  130  may be equipped with a baffle  64 ,  86 ,  95  in baffle area  132  of header tank  128  to limit coolant flow and heat transfer to thereby lessen thermal strain in, for example, area  138 , which is a boundary between the two tube and fin sections  134 ,  136 . More specifically, partition  140  may be a dividing point between tube and fin section  134  and tube and fin section  136 . An engine coolant may enter heat exchanger  126  at inlet  142  and traverse a path indicated with fluid  144  and exit at outlet  143 . During passage through header tank  128 , baffle within baffle area  132  may restrict the volume of fluid that passes into the lowest chamber of tube and fin section  134  that abuts the highest chamber of tube and fin section  136 , thus reducing thermal strain along area of partition  140  of the heat exchanger  126  because fluid  144  may be at it coolest in the lowest chamber of tube and fin section  134 . Fluid  146  entering inlet  148  is cooled before passing into the upper chamber of tube and fin section  136  and subsequently exiting from outlet  150 . Tube and fin sections  134 ,  136  may be equipped with tubes  66  and fins  68  depicted in  FIG. 5 . If so equipped, tubes  66  may run horizontally across heat exchanger  126  to fluidly link header tanks  126 ,  130 . 
     When an element or layer is referred to as being “on”, “engaged to”, “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to”, “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Spatially relative terms, such as “inner,” “outer,” “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.