Abstract:
A condenser assembly including a plurality of heat-exchanger pipes, which are arranged equidistant from each other having corrugated fins arranged therebetween and lead into deflection regions at both ends and have a free length used for heat exchange and, in connection with the corrugated fins, form a frontal area having a width corresponding to the free length of the heat-exchanger pipes and a height, such that the frontal area results from the product of width and height. The heat-exchanger pipes are connected in parallel in groups and the individual groups are connected in series. The heat-exchanger pipes of the individual groups are arranged adjacent and each group has at least two heat-exchanger pipes. The percentage share of the heat-exchanger pipes of the first group results from 26.162 In (S/dm2)−40.746≦P≦25.49 In (S/dm2)−27.842 for a frontal area.

Description:
[0001]    This nonprovisional application is a continuation of International Application No. PCT/EP2014/054891, which was filed on Mar. 12, 2014, and which claims priority to German Patent Application No. 10 2013 204 294.9, which was filed in Germany on Mar. 12, 2013, and which are both herein incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a condenser assembly. 
         [0004]    2. Description of the Background Art 
         [0005]    Not insignificant drops in performance in the area of the refrigerant circuit result when refrigerant R1234yf is used instead of the current refrigerant R134a in vehicle climate control systems. In order to increase the refrigerant circuit performance, for example, greater supercooling of the already liquefied refrigerant is possible; i.e., the refrigerant is cooled in a supercooling region to a temperature below the condensation temperature of the refrigerant. 
         [0006]    A condenser assembly of a vehicle climate control system for refrigerants with this type of approach for increasing performance is known, for example, from DE 10 2010 039 511 A1, which corresponds to US 2013/0219932, and which is incorporated herein by reference. This known condenser assembly provides a collecting tank on a first longitudinal side of the refrigerant condenser assembly, two headers, heat exchanger tubes in a superheat region for cooling the vaporous refrigerant, a condensation region for condensing the refrigerant, and a supercooling region wherein the supercooling region is formed with three cooling sections, whereby at least two heat exchanger tubes as a first supercooling parallel section are supplied in parallel with the refrigerant in a fluid-conducting manner, the refrigerant flowing out of the first supercooling parallel section flows into a first supercooling intermediate flow channel. This first supercooling intermediate flow channel opens into at least two heat exchanger tubes as the second supercooling parallel section. This second parallel supercooling section opens into a second supercooling intermediate flow channel. The second supercooling intermediate flow channel opens into at least two heat exchanger tubes as the third parallel supercooling section, whereby an outlet opening is disposed on a second longitudinal side of the refrigerant condenser assembly. 
         [0007]    In conventional condenser assemblies, however, an enlarged supercooling section, formed by three regions connected in series, at a comparable overall size of the condenser assembly, results in a reduced condensation region, whereby the high pressure in the refrigerant circuit increases. Such a condenser assembly therefore still leaves much to be desired in regard to cooling performance and efficiency. 
       SUMMARY OF THE INVENTION 
       [0008]    It is therefore the object of the present invention to provide a condenser assembly that has a better cooling performance and a higher efficiency. 
         [0009]    By means of a condenser assembly design in which the percentage share of the heat exchanger tubes of the first group results from 
         [0000]      26.162 In (S/dm 2 )−40.746≦P≦25.49 In (S/dm 2 )-27.842
 
         [0010]    for a frontal area (S) having a width to height ratio in the range from 0.5 to 1.0, a frontal area in the range from 10 to 30 dm 2 , and a specification of the area of the frontal area in dm 2  (in the argument of the natural logarithm), an optimized cooling performance results compared with condenser assemblies that have a greater or lower percentage share of heat exchanger tubes of the first assembly in terms of the aforementioned relationship. 
         [0011]    In particular, the percentage share of the heat exchanger tubes of the first group results from 
         [0000]      26.162 In (S/dm 2 )−35.746≦P≦25.49 In (S/dm 2 )−32.842
 
         [0012]    Such a design can be used in particular for condensers with a supercooling region, which has three cooling sections with at least two tubes in each cooling section. 
         [0013]    Both R134 and R1234yf can be used as refrigerants but other refrigerants as well that have properties approximately comparable to R134 or R1234yf. 
         [0014]    At an Lh to Lv ratio of 0.5, the percentage share results preferably from: 
         [0000]      26.162 In (S/dm 2 )−40.746≦P≦28.162 In (S/dm 2 )−30
 
         [0015]    and at an Lh to Lv ratio of 1.0 from: 
         [0000]      25.49 In (S/dm 2 )−35≦P≦25.49 in (S/dm 2 )−27.842.
 
         [0016]    The condenser assembly can have at least four regions connected in series, whereby the first region of the regions connected in series accounts for the percentage share of an entire frontal area. In this case, the percentage share of the regions connected in series can decrease in the normal flow direction of the refrigerant from the first region to the second region. Further, the percentage share of the regions connected in series can decrease in the normal flow direction of the refrigerant from the second region to the third region. 
         [0017]    The percentage share of the regions connected in series decreases in the normal flow direction of the refrigerant at the beginning of the series and is constant at the end of the series. 
         [0018]    In an exemplary condenser assembly, the percentage share of the first region of six regions, connected in series in the normal flow direction of the refrigerant, is greater than the percentage share of the second region, and the percentage share of the third region in each case is preferably the same as the percentage share of the fourth region, the fifth region, and the sixth region. 
         [0019]    In the case of a square design of the frontal area, the percentage share of the first region of six regions, connected in series in the normal flow direction of the refrigerant, is preferably twice as large as the percentage share of the second region, and the percentage share of the third region in each case is preferably the same as the percentage share of the fourth region, the fifth region, and the sixth regions, whereby the sum of the percentage shares of the third, fourth, fifth, and sixth region is preferably the same as the percentage share of the second region, and the percentage share of the first region is preferably the same as the sum of the percentage shares of the rest of the regions. 
         [0020]    The deflection regions can be disposed within headers, whereby the refrigerant-receiving volume of the headers in the normal flow direction of the refrigerant in a first deflection region between the first region and the second region is preferably greater than in a second deflection region between the second region and the third region, whereby a collecting tank is disposed preferably after the third region. 
         [0021]    The invention is especially suitable for condenser assemblies with a triple-flow supercooling region with in each case at least two heat exchanger tubes, but can also be used for other condenser assemblies, for example, with a single-flow supercooling region and triple-flow condensation region. 
         [0022]    Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein: 
           [0024]      FIG. 1  shows a schematic illustration of a condenser assembly with three cooling sections according to the first exemplary embodiment; 
           [0025]      FIG. 2  shows a partial schematic illustration of a heat exchanger surface of the condenser assembly of  FIG. 1 ; 
           [0026]      FIG. 3  shows a schematic illustration of a condenser assembly with three cooling sections according to the second exemplary embodiment; and 
           [0027]      FIG. 4  shows a diagram of the percentage share of the heat exchanger tubes of a first region versus the heat exchanging frontal area. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    A condenser assembly  1 , which is part of a vehicle climate control system (not shown in greater detail) with an evaporator disposed in a refrigerant circuit and a compressor, has a first and second longitudinal side Lv or Lh, respectively, positioned laterally. Condenser assembly  1  is typically installed in a motor vehicle such that both longitudinal sides Lv, Lh extend substantially in the vertical direction (y-direction) and are arranged spaced apart in the z-direction. The depth of condenser assembly  1  extends in the x-direction, whereby the x-direction corresponds to the air flow direction through condenser assembly  1 , i.e., it runs opposite to the normal direction of travel of the vehicle. Corresponding specifications of directions will be used hereinafter to describe condenser assembly  1 . 
         [0029]    On first longitudinal side Lv at the top on condenser assembly  1 , an inlet opening  2  is disposed, through which the refrigerant, in the present case R1234yf, circulated in the refrigerant circuit, enters condenser assembly  1 . Header  3 , continuous in the present case, is disposed on each longitudinal side Lv, Lh of condenser assembly  1 . Headers  3  are connected to one another in a manner known per se via heat exchanger tubes  4 , formed by flat tubes. Baffles are disposed in headers  3  in order to predefine the flow path (indicated schematically by arrows in the drawing) of the refrigerant through heat exchanger tubes  4  and to separate individual deflection regions from one another. Corrugated fins  5 , which have a thermal and mechanical connection with heat exchanger tubes  4  and increase the heat exchange surface area of heat exchanger tubes  4  and thereby of condenser assembly  1 , are disposed in a known manner between heat exchanger tubes  4 . 
         [0030]    The heat exchanging region of condenser assembly  1  in the present case is flown through in a z-shaped manner in the much larger top region, whereby the height and thereby the number of parallel-arranged heat exchanger tubes  4 , through which refrigerant flows in one direction, decrease greatly downwards before the refrigerant at the bottom end of this top region, obliquely opposite to inlet opening  2 , flows into a collecting tank  6 , which is constructed in a conventional manner parallel to a header  3  disposed on second longitudinal side Lh and in which a dryer and filter (not shown) are disposed. In this case, reference is made to the top group of heat exchanger tubes  4 , with parallel flow in one direction, of this top region as the first flow path (first region A), to the middle group of heat exchanger tubes  4 , with parallel flow opposite to the top group, of this top region as the second flow path (second region B), and to the bottom group of heat exchanger tubes  4 , with parallel flow opposite to the middle group, of this top region as the third flow path (third region C). These individual regions A-C are each connected in series via said deflection regions. Because of the function, namely, that in the corresponding top region of condenser assembly  1  the overheated gaseous refrigerant is cooled to a saturation temperature, the first region A is also called the superheat region. The second and third region B and C together are called the condensation region, because in this region the refrigerant cooled to the saturation temperature is condensed and then enters collecting tank  6  as a fluid. 
         [0031]    A supercooling region  7  as a further part of condenser assembly  1 , to which refrigerant liquefied in the condensation region is supplied, is provided as a smaller bottom region downstream of collecting tank  6 . The flow in said supercooling region  7  in the present case is also z-shaped, proceeding from the bottom end region of collecting tank  6 . In keeping with DE 10 2010 039 511 A1, supercooling region  7  is formed by three cooling sections, in each case by two heat exchanger tubes, running parallel to one another, and deflection regions disposed therebetween in header  3 , whereby at the end the refrigerant enters an outlet opening  8  via header  3  disposed on first longitudinal side Lv. According to the designation of the regions of the larger top region A-C, reference is made to these heat exchanger tubes in the sequence of the normal throughflow with the refrigerant as regions D, E, and F. The deflection of the refrigerant in supercooling region  7  between the individual cooling sections occurs in the present case in headers  3  by baffles, in keeping with the deflection in the larger top region; it can also occur in any other manner, however; i.e., headers  3  can also end, for example, above supercooling region  7  and the deflection can occur by means of separately formed deflection regions. 
         [0032]    Headers  3 , heat exchanger tubes  2 , corrugated fins  5 , and optionally the deflection regions usually are formed of metal, in the present case of aluminum. The individual components in the present case are connected together by material bonding as solder connections but a different fabrication with a suitable structure is also conceivable. 
         [0033]    The design of the flow paths for an optimal cooling performance of condenser assembly  1  will be elaborated upon hereafter. In this regard, reference is made to the area which lies in the yz-plane and is defined as frontal area S below in the z direction by the (free) length Lh of heat exchanger tubes  4  between headers  3  and in the y-direction by the distance Lv between the top and bottom edge of the respective topmost or lowest corrugated fin; i.e., the frontal area S results from Lh×Lv. Reference is made to Lh below also as the width and to Lv also as the height. The (free) length Lh of the individual heat exchanger tubes  4  in the region of frontal area S is the same in each case in the described embodiment. It can also be different, however, in alternative embodiments. Further, all heat exchanger tubes  4  with free flow cross sections, corresponding to one another and constant over the length of heat exchanger tubes  4 , and all heat exchanger tubes  4  are arranged equidistant from each other over the height of condenser assembly  1 . 
         [0034]    The entire flow path of the refrigerant within heat exchanging region A-C and accordingly of supercooling region D-E results based on the deflection in each case approximately as 3×Lh, whereby in each case a plurality of parallel heat exchanger tubes  4  are provided within the individual regions A-F, and the number of parallel-connected heat exchanger tubes  4  in regions A, B, and C decreases in the direction of the flow path. The number of parallel-connected heat exchanger tubes  4  in regions D-E is constant in the present case. It can also correspond to the number of parallel-connected heat exchanger tubes in region C. In the present case, the number of parallel-connected heat exchanger tubes in regions C-F is two in each case. 
         [0035]    Insofar as they are described above, the two exemplary embodiments in  FIGS. 1 and 3  correspond to one another. 
         [0036]    The ratio of the number of heat exchanger tubes (and thereby the area proportion in regard to frontal area S) of first region A, designated below as nA, to the number of heat exchanger tubes nB of second region B is essential for optimizing the cooling performance of condenser assembly  1 . The effect of third region C with nC heat exchanger tubes is of minor importance for the performance of condenser assembly  1 . The number of heat exchanger tubes in the fourth to sixth region nD, nE, and nF is also of minor importance. 
         [0037]    The percentage share of the heat exchange area of first region A in relation to the entire heat exchange area, i.e., to the entire frontal area S, is designated by P hereafter. 
         [0038]    At an Lh to Lv ratio in the range from 0.5 to 1.0 and a specification of the area in dm 2 , at a relation of: 
         [0000]      26.162 In (S/dm 2 )−35.746≦P≦25.49 In (S/dm 2 )−32.842,
 
         [0039]    this results in the share of heat exchanger tubes  4 , associated with the first region, in regard to the total number of heat exchanger tubes  4  as a percentage, which leads to an optimal performance of a climate control system with a condenser assembly  1  designed according to the invention. The bottom limit in this case for an Lh to Lv ratio is 0.5, and the top limit for an Lh to Lv ratio is 1.0. 
         [0040]    In other words, for example, an advantageous share of heat exchanger tubes  4  for a heat exchanging frontal area S of 25 dm 2  in the first region of about 54% results. Thereby, a corresponding ratio P (in %) of the number of heat exchanger tubes  4  of first region A to the total number of heat exchanger tubes  4  of: 
         [0000]      P=nA/[100×(nA+nB+nC+nD+nE+nF)]
 
         [0041]    also results automatically with a “square” design of the frontal area. Accordingly, a condenser assembly  1  with a ratio of Lh/Lv of 1.0 is shown in  FIG. 1  as the first exemplary embodiment. 
         [0042]    At an Lh to Lv ratio of 0.5, therefore in the case of a width that is twice as large as the height of the frontal area, an advantageous share (of heat exchanger tubes  4  in first region A) of about 43% results, as shown schematically in  FIG. 3  as the second exemplary embodiment. It should be mentioned as a precaution that the basic structure of the heat exchanging area with heat exchanger tubes  4  and corrugated fins  5  does not differ. The sole difference is the arrangement of the baffles (not shown in greater detail) in headers  3 , which result in a different throughflow direction in the subsections of the heat exchanging area; that is, the first change in direction is slightly farther above in relation to the total height in condenser assembly  1  according to the second exemplary embodiment. 
         [0043]    Thus, in the case of a square design of frontal area S and a height of the same of about 25 dm 2 , as provided according to the first exemplary embodiment, about half of all heat exchanger tubes  4  are associated with first region A. If frontal area S is enlarged, however, thus the share of heat exchanger tubes  4  to be associated advantageously with first region A increases, and if the size of frontal area S is decreased, thus the share declines to about 30% in the case of an frontal area S of, for example, 10 dm 2 . 
         [0044]    In the case of a rectangular design of frontal area S with an Lh to Lv ratio of 0.5, as provided according to the second exemplary embodiment, the percentage share of first region A is about 10% lower. 
         [0045]    With consideration of a safety margin of 5% upwards and downwards, a relation of 
         [0000]      26.162 In (S/dm 2 )−40.746≦P≦25.49 In (S/dm 2 )−27.842
 
         [0000]    for the share of heat exchanger tubes  4 , associated with the first region, results in relation to the total number of heat exchanger tubes  4  as a percent, which leads to a good performance of a climate control system with a condenser assembly  1  made according to the invention. 
         [0046]    The above relation holds in particular for frontal areas S in the range from 10 to 30 dm 2 , particularly in the range from 15 to 25 dm 2 , whereby the plurality of condensers used in the automotive sector have a suitably large frontal area S. 
         [0047]    According to the first and second exemplary embodiment, second region B is made approximately as large as the third to sixth regions C-F together. 
         [0048]    A suitable relation for the percentage design of first region A in regard to the entire heat exchanging frontal area S can also be used if the supercooling region is made not as a triple-flow region as described above, but as a double-flow or multiflow region, whereby the number of flat tubes in the supercooling region is at least 6 to 16 overall. Therefore, the above equation for P can also be used as equal to zero for nE and/or nF, provided the sum of the heat exchanger tubes in the supercooling region is within the range of 6 to 16. 
         [0049]    Although described as continuous tubes with baffles according to the present exemplary embodiment and in the drawing, headers  3  can also be formed by individual, separately formed deflection regions; in particular, the flow cross sectional area and/or volume thereof can decrease in the flow direction of the refrigerant, as disclosed in DE 10 2011 007 216 A1, which is incorporated herein by reference. A corresponding flow cross section area decrease is advantageous particularly between the first deflection region (area between region A and region B) and the second deflection region (area between region B and region C), but it can be provided advantageously in addition between the following regions. 
         [0050]    The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.