EP1310757B1

EP1310757B1 - Stacked-type multi-flow heat exchangers

Info

Publication number: EP1310757B1
Application number: EP02257053A
Authority: EP
Inventors: Tomohiro C/O Sanden Corporation Chiba
Original assignee: Sanden Corp
Current assignee: Sanden Corp
Priority date: 2001-11-08
Filing date: 2002-10-10
Publication date: 2005-12-21
Anticipated expiration: 2022-10-10
Also published as: CN1310006C; EP1310757A3; DE60208146T2; EP1310757A2; CN1417551A; DE60208146D1; KR20030038484A; JP2003148833A

Description

The present invention relates to stacked-type multi-flow heat exchangers for use in an air conditioner for vehicles.
Stacked-type multi-flow heat exchangers for use in an air conditioner for vehicles, which include a plurality of heat transfer tubes and a plurality of fins, stacked alternately, are known in the art. Such known stacked-type multi-flow heat exchangers may be used as evaporators in air conditioners for vehicles. In vehicle air conditioners there has been high demand to decrease the space of installation of the air conditioner. Therefore, thinning the depth dimension, i.e., the dimension of the direction for the passing of air, of a evaporator, and in order to decrease the space of the installation of the evaporator, providing connection portions for introducing or discharging refrigerant on one side surface of the evaporator are desirable. Moreover equalizing the air temperature passing through the evaporator is also desirable to produce a high performance air conditioner.
Therefore, in order to thin the depth dimension of the evaporator, and decrease the space of the installation of the evaporator, heat exchangers are proposed in Japanese Utility Model (Unexamined) Publication No. H7-12778 shown in Fig. 9, and Japanese Patent (Unexamined) Publication No. H9-17850 shown in Fig. 10.
As shown in Fig. 9, a heat exchanger 100 has an upper tank 102 and a lower tank 103. Upper tank 102 and lower tank 103 are communicated by a group of tubes 101. Upper tank 103 includes an upstream tank 104 and a downstream tank 105 with respect to their flow direction A', respectively. Upstream tank 104 has an inner space divided by a partitioning plate 106 into chambers 107 and 108. Likewise, downstream tank 105 has an inner space divided by a partitioning plate 109 into chambers 110 and 111. Chamber 108 of upstream tank 104 and chamber 111 of downstream tank 105 are communicated by a communicating path 112. Lower tank 103 includes an upstream tank 113 and a downstream tank 114 with respect to the air flow direction A', respectively.
In heat exchanger 100, the heat exchange medium introduced through a fluid inlet portion 115 provided at chamber 107 of upstream tank 104 passes through heat exchanger 100 as illustrated in Fig. 9, and is discharged from a fluid outlet portion 116 provided at chamber 110 of downstream tank 105.
In addition, as shown in Fig. 10, a heat exchanger 117 has an upper tank 118 and a lower tank 119. Upper tank 118 and lower tank 119 are communicated by a group of 5 tubes 120. Upper tank 118 includes an upstream tank 121 and a downstream tank 122 with respect to the air flow direction A", respectively. Upstream tank 121 has an inner space divided by a partitioning plate 123 into chambers 124 and 125. Moreover, lower tank 119 includes an upstream tank 126 and a downstream tank 127. Downstream tank 127 has an inner space divided by a partitioning plate 128 into chambers 129 and 130. Chamber 125 of upstream tank 121 and chamber 130 of downstream tank 127 are communicated by a communicating path 131.
In heat exchanger 117, the heat exchange medium introduced through a fluid inlet portion 132 provided at chamber 129 of downstream tank 127 passes through heat exchanger 117 as illustrated in Fig. 10, and is discharged from a fluid outlet portion 133 provided at chamber 124 of upstream tank 121. In heat exchanger 117, communicating path 131 projecting in the direction of the laminated group of tubes 120, and fluid inlet portion 132 and fluid outlet portion 133 are provided at one side surface of heat exchanger 117, so that the space of the installion of heat exchanger 117 is decreased. Moreover, heat exchanger 117 has a structure that does not overlap a part of the group of tubes 120, easily introducing vapor phase refrigerant due to inertial force of a vapor-liquid refrigerant and another part of the group of tubes 120 easily introducing liquid phase refrigerant in the air flow direction A". Therefore, the air temperature passing through heat exchanger 117 is equalized in an entire of the group of tubes 120.
Nevertheless, there is a demand further to achieve a thin-profile, i.e. to decrease the depth dimension of the heat exchangers (for example, decrease the depth dimension to less than or equal to 40mm).
However, if the depth dimension of heat exchanger 100 shown in Fig. 9 or' heat exchanger 117 shown in Fig. 10, both of which have four refrigerant flow paths, is directly decreased, problems may arise. If the depth dimension of heat exchanger 100 or heat exchanger 117 is decreased, the cross-sectional area of a flow path of each tube is also decreased, and pressure loss of refrigerant increases. As a result, quantity of refrigerant in circulation may be reduced or the temperature of refrigerant at the introduction to heat exchanger 100 or heat exchanger 117 may be increased, and the efficiency of heat exchange may be reduced. On the other hand, if one of partitioning plates is removed from heat exchanger 100 or heat exchanger 117 and refrigerant flow paths are reduced to suppress the pressure loss, the air temperature passing through heat exchanger 100 or heat exchanger 117 may not be equalized. For example, referring to Fig. 9, if partitioning plate 109 is removed, refrigerant flowing from communicating path 112 should flow into all tubes equally. Nevertheless, the refrigerant flow path in the width direction of the tanks is lengthened equally, and flow of the refrigerant into all of the tubes is difficult due to a difference between inertial force of a vapor a refrigerant and inertial force of a liquid refrigerant.
In addition, heat exchanger 100 shown in Fig. 9 or heat exchanger 117 shown in Fig. 10 include a communicating path having a smaller cross-sectional area along the refrigerant flow path, and the refrigerant is concentrated into the communicating path. Therefore, pressure loss is more likely to arise. Moreover, the communicating path hardly contributes to the heat exchange. Further, communicating path 131 of heat exchanger 117 shown in Fig. 10 is projected in the width direction. Therefore, in heat exchangers having a side tank for introducing or discharging the heat exchange medium in the width direction, the dimension of the width direction of heat exchangers may increase.
Therefore, a need has arisen for stacked-type multi-flow heat exchangers for use in vehicle air conditioners that overcome these and other shortcomings of the related art. A technical advantage of the present invention is to suppress the pressure loss of refrigerant, to equalize the air temperature passing through the heat exchanger, and to achieve the reduced size, especially the thin-profile of the heat exchanger, in the stacked-type multi flow heat exchangers.
EP-A-769665 discloses a refrigerant evaporator, improved for uniform temperature of air blown out therefrom.
Accordingly, the invention resides in a heat exchanger, the heat exchanger comprising:
a pair of first opposed tank portions, provided at a downstream side of air passing through said heat exchanger;
a pair of final opposed tank portions, provided at an upstream side of the air passing through said heat exchanger;
a first heat exchange portion, said first heat exchange portion being disposed at a downstream side of the air passing through said heat exchanger and having a first group of tubes, said first group of tubes extending between said pair of first opposed tank portions to form a first route of a heat exchange medium; and
a final heat exchange portion, said final heat exchange portion being disposed at an upstream side of the air passing through said heat exchanger and at a back side of said first heat exchange portion, said final heat exchange portion having a final group of tubes, said final group of tubes extending between said pair of final opposed tank portions to form a final route of said heat exchange medium,

said heat exchanger further comprises:
a communicating heat exchange portion, which is disposed at both said upstream side and said downstream side of the air passing through said heat exchanger, said communicating heat exchange portion having a communicating group of tubes; and
a pair of opposed communicating tanks, between which said communicating group of tubes extends to form a communicating route of said heat exchange medium; and
said first heat exchange portion and said final heat exchange portion are provided at a heat exchange medium inlet and outlet side, and said communicating heat exchange portion is provided at a side opposite to said heat exchange medium inlet and outlet side.

The present invention may be more readily understood with reference to the following drawings, in which:
Fig. 1 is a perspective view of a stacked-type multi-flow heat exchanger, according to a first embodiment of the present invention;
Fig. 2 is a front view of the stacked-type multi-flow heat exchanger depicted in Fig. 1;
Fig. 3 is a top view of the stacked-type multi-flow heat exchanger depicted in Fig. 1;
Fig. 4 is a plan view of a first tube plate, a pair of which form a heat transfer tube for a first heat exchange portion and a final heat exchange portion of the stacked-type multi-flow heat exchanger depicted in Fig. 1;
Fig. 5 is a plan view of a second tube plate, a pair of which form a heat transfer tube for a communicating heat exchange portion of the stacked-type multi-flow heat exchanger depicted in Fig. 1;
Fig. 6 is a perspective view showing a flow of a heat exchange medium in the stacked-type multi-flow heat exchanger depicted in Fig. 1; Fig. 7 is a side view of the stacked-type multi-flow heat exchanger depicted in Fig. 1;
Fig. 8 is a perspective view showing flow of a heat exchange medium in a stacked-type multi-flow heat exchanger, which corresponds to Fig. 6, according to a second embodiment of the present invention;
Fig. 9 is a perspective view showing flow of a heat exchange medium in a known stacked-type multi-flow heat exchanger; and
Fig. 10 is a perspective view showing flow of a heat exchange medium in another known stacked-type multi-flow hear exchanger.
Referring to Figs. 1-7, a stacked-type multi-flow heat exchanger according to a first embodiment is described. As shown in Figs. 1-3, a stacked-type multi-flow heat exchanger 1 includes a plurality of heat transfer tubes 2 and a plurality of fins 3 stacked alternately. Stacked heat transfer tubes 2 and fins 3 form heat exchanger core. A side tank 4 is provided on the one side of heat exchanger core, and an end plate 5 is provided on the other side of heat exchanger core.
A set of tubes 6 comprising the plurality of heat transfer tubes 2 includes a first set of tubes 7 and a second set of tubes 8. First set of tubes 7 is stacked by the plurality of heat transfer tubes 2, and each of heat transfer tubes 2 are formed by a pair of tube plates 9 connected to each other. As shown in Fig. 4, tube plate 9 has concave portions 10 and 11 in the longitudinal direction. Concave portions 10 and 11 are partitioned by a wall 12. Projecting hollow portions 13, 14, 1, and 16 are formed on the respective corner portions of tube plate 9. By connecting the pairs of tube plates 9 (to produce first set of tubes 9), a first group of tubes, providing a first refrigerant route 17, and a final group of tubes, providing a final refrigerant route 18, are formed in heat transfer tubes 2, as shown in Fig. 6. In addition, referring again to Fig. 4, a number of bosses 19, which project toward refrigerant flow routes 17 and 18, are formed on concave portion 10 and 11 of tube plate 9. When the pair of tube plates 9 are connected, the bosses 19 abut each other. The number of bosses 19 may increase the heat exchange efficiency and strengthen withstanding of the pressure of refrigerant. In this embodiment of the present invention, the pair of tube plates 9 are connected, and they are stacked alternately. As a result, the set of tubes 7, a first upstream tank 33, a first downstream tank 34, a second upstream tank 37, and a second downstream tank 38 are constituted
In this embodiment, the second downstream tank 38 and first downstream tank 34 constitute a pair of first opposed tank portions.
Moreover, in this embodiment, inner fins having a wave shaped cross-section may be provided in refrigerant flow routes 17 and 18 instead of bosses 19.
A second set of tubes 8, constituting a communicating group of tubes, is stacked by the plurality of heat transfer tubes 2, and each of heat transfer tubes 2 are formed by pairs of tube plates 20 connected to each other. As shown in Fig. 5, tube plate 20 has concave portions 21 and 22 in the longitudinal direction. Concave portions 21 and 22 are partitioned by a wall 23. Projecting hollow portions 24, 25, 26, and 27 are formed on the respective corner portions of tube plate 20. Projecting hollow portions 24 and 26, and projecting hollow portions 25 and 27 communicate with each other respectively. By connecting the pair of tube plates 20, a pair of refrigerant flow routes 28 and 29, constituting a communicating flow route, are formed in heat transfer tubes 2, as shown in Fig. 6. Nevertheless, because projecting hollow portions 24 and 26, and projecting hollow portions 25 and 27 communicate with each other, respectively, the heat exchange medium flows in the same direction in refrigerant flow routes 28 and 29. In addition, referring again to Fig. 5, a number of bosses 30, which project toward refrigerant flow routes 28 and 29, are formed on concave portion 21 and 22 of tube plate 20. When the pair of tube plates 20 are connected, the bosses 30 abut each other. The number of bosses 30 may increase the heat exchange efficiency and strengthen withstanding of the pressure of refrigerant. In this embodiment of the present invention, the pair of tube plates 20 are connected, and they are stacked alternately. As a result, the second set of tubes 8 and a pair of opposed communicating tanks, i.e. an upper communicating tank 35, and a lower communicating tank 39, are constituted. Moreover, in this embodiment, inner fins having a wave shaped cross-section may be provided in refrigerant flow routes 28 and 29 instead of bosses 30.
As shown in Figs 1-3, and 6, an upper tank 31 is provided on an upper portion of the set of tubes 6 and a lower tank 32 is provided on a lower portion of the set of tubes 6. In this specification, "upper" or "lower" is described for the purpose of understanding the invention. Therefore, "upper" or "lower" may be reversed in the present invention. Upper tank 31 includes first upstream tank 33, first downstream tank 34, and upper communicating tank 35. First upstream tank 33 and first downstream tank 34 are provided with respect to the air flow direction A, respectively. Upper communicating tank 35 communicates with first downstream tank 34. A partitioning plate 36 is provided between first upstream tank 33 and upper communicating tank 35.
Lower tank 32, which communicates with upper tank 31 via the set of tubes 6, includes second upstream tank 37, second downstream tank 38, and lower communicating tank 39. Second upstream tank 37 and second downstream tank 38 are provided with respect to the air flow direction A, respectively. Lower communicating tank 39 is communicated with second upstream tank 37. A partitioning plate 40 is provided between second downstream tank 38 and lower communicating tank 39.
In this embodiment, the second upstream tank 37 and first upstream tank 33 constitute a pair of final opposed tank portions.
A heat exchange medium introducing route 41 and a heat exchange medium discharging route 42 are formed in side tank 4, which is provided on one side of heat exchanger 1. Introducing route 41 is communicated with second downstream tank 38. Discharging route 42 communicates with first upstream tank 33. As shown in Figs. 1 and 7, a flange 43 is attached to side tank 4 and is connected to an expansion valve (not shown). A heat exchange medium inlet port 44 and a heat exchange medium outlet port 45 are provided at flange 43.
Referring to Fig. 6, a heat exchange medium route in heat exchanger 1 is described. A heat exchange medium, for example refrigerant, is introduced into introducing route 41 from inlet port 44, and flows into second downstream tank 38. Subsequently, the heat exchange medium flows into first downstream tank 34 via refrigerant flow route 17 of the first set of tubes 7. Refrigerant flow route 17 between second downstream tank 38 and first downstream tank 34 constitutes a first heat exchange portion 46. The heat exchange medium flowing out of first downstream tank 34 flows into upper communicating tank 35, and flows into lower communicating tank 39 via refrigerant flow routes 28 and 29 of the second set of tubes 8. Refrigerant flow routes 28 and 29 between upper communicating tank 35 and lower communicating tank 39 constitute a communicating heat exchange portion 47. Moreover, the heat exchange medium flowing out of lower communicating tank 39 flows into second upstream tank 37, and flows into first upstream tank 33 via refrigerant flow route 18 of the first set of tubes 7. Refrigerant flow route 18 between second upstream tank 37 and first upstream tank 33 constitutes a final heat exchange portion 48. The heat exchange medium flowing out of first upstream tank 33 is discharged from outlet port 45 via discharging route 42. Specifically, in heat exchanger 1, first heat exchange portion 46 is provided at the downstream side of the air flow direction A, and final heat exchange portion 48 is provided at the upstream side of the air flow direction A. Moreover, communicating heat exchange portion 47 communicating between first heat exchange portion 46 and final heat exchange portion 48 is provided at a side opposite to inlet port 44 and outlet port 45 and adjacent to first heat exchange portion 46 and final heat exchange portion 48.
In the first embodiment of the present invention, refrigerant flow route 17 provided at the downstream side of the air flow direction A constitutes first heat exchange portion 46, and refrigerant flow route 18 provided at the upstream side of the air flow direction A constitutes final heat exchange portion 48. Moreover, refrigerant flow routes 28 and 29 constitute communicating heat exchange portion 47. In this embodiment, even if heat exchanger 1 is of thin-profile, at least three heat exchange portions are provided. Therefore, while a cross-sectional area of the refrigerant route per one heat exchanger portion is ensured, the length of the refrigerant route in each tank in the longitudinal direction is reduced. Consequently, the pressure loss of the heat exchange medium flowing in heat exchanger 1 may be reduced or eliminated, and occurrence of the temperature differential of the heat exchange medium between each tube constituting each heat exchanger portion may be reduced or eliminated. In addition, in heat exchanger 1, communicating heat exchange portion 47 functions as a communicating portion between final heat exchange portion 48 at the upstream side of the air flow direction A and first heat exchange portion 46 at the downstream side of the air flow direction A. As a result, reduction of the pressure loss at the communicating heat exchange portion 47 may be achieved, and the dimension of the width direction of heat exchanger 1 may be reduced without decreasing the heat exchange performance.
In addition, the refrigerant flow route in heat exchanger 1 is formed of first heat exchange portion 46, communicating heat exchange portion 47, and final heat exchange portion 48, and is arranged in this order. Therefore, the heat exchange medium having a higher temperature may flow into final heat exchange portion 48 compared with that flowing into other heat exchange portions. Nevertheless, the heat exchange medium having a lower temperature flows into first heat exchange portion 46 and first heat exchange portion 46 is provided at the downstream side of the air flow direction A, at the back side of final heat exchange portion 48. Therefore, if the air passing through final heat exchange portion 48 is not sufficiently heat-exchanged, the air may pass through first heat exchange portion 46, and the air may be sufficiently heat-exchanged at first heat exchange portion 46. Consequently, the occurrence of the temperature differential of the air passing through heat exchanger 1 may be reduced or eliminated.
Moreover, in heat exchanger 1, if the heat exchange medium is introduced from upper tank 31, the heat exchange medium is discharged from lower tank 32, as a necessity. On the contrary, if the heat exchange medium is introduced from lower tank 32, the heat exchange medium is discharged from upper tank 31. Specifically, heat exchange medium introducing route 41 and heat exchange medium discharging route 42 at side tank 4 may be disposed in relation to the vertical position. Therefore, if heat exchanger 1 is of thin profile, each cross-sectional area of introducing route 41 and discharging route 42 at side tank 4 may be sufficiently ensured, and the pressure loss of the heat exchange medium in side tank 4 may be reduced or eliminated.
Referring to Fig. 8, a stacked-type multi-flow heat exchanger 50 according to a second embodiment is described. In the following explanation, the same reference numbers are used to represent the same parts of stacked-type multi-flow heat exchanger 1 as shown in Figs. 1-7, and the explanation of the same parts is omitted. As shown in Fig. 8, in the second embodiment of the present invention, a partitioning plate 51 is disposed in first downstream tank 34 and a partitioning plate 52 is disposed in second upstream tank 37.
Therefore, a refrigerant flow route is formed in heat exchanger 50, as follows. In heat exchanger 50, the heat exchange medium introducing heat exchange medium introducing route 41 flows into second downstream tank 38, and flows into first downstream tank 34 via a refrigerant flow route 17a of the first set of tubes 7. Refrigerant flow route 17a between a portion of second downstream tank 38 (disposed to one side of partition 40) and a portion of first downstream tank 34 positioned thereabove (which together constitute a pair of first opposed tank portions) constitutes first heat exchange portion 53. Moreover, because a partitioning plate 51 is disposed in first downstream tank 34 and partitions upper communicating tank 35 and first downstream tank 34, the heat exchange medium flowing out of first downstream tank 34 flows into second downstream tank 38 via refrigerant flow route 17b. Refrigerant flow route 17b, which is between another portion of first downstream tank 34 and another portion of second downstream tank 38 (disposed to the other side of partition 40) positioned therebelow (together constituting a pair of second opposed tank portions), constitutes a second heat exchange portion 54. Subsequently, the heat exchange medium flowing out of lower tank 32 flows into lower communicating tank 39, and flows into upper communicating tank 35 via refrigerant flow routes 28 and 29. Refrigerant flow routes 28 and 29 between lower communicating tank 39 and upper communicating tank 35 constitute a communicating heat exchange portion 55.
Subsequently, the heat exchange medium flows out of upper communicating tank 35. The heat exchange medium then flows into a portion of first upstream tank 33 (disposed to one side of partition 36, i.e. at a side opposite to inlet port 44 and outlet port 45), and then flows into a portion of second upstream tank 37 positioned below that portion, via a refrigerant flow route 18a, the said portions together constituting a pair of penultimate opposed tank portions. Refrigerant flow route 18a constitutes a penultimate heat exchange portion 56. Moreover, the heat exchange medium flowing out of another portion of second upstream tank 37 flows into another portion of first upstream tank 33 (disposed to one side of partition 36, i.e. to the same side as inlet port 44 and outlet port 45) positioned above that portion, via a refrigerant flow route 18b the said portions together constituting a pair of final opposed tank portions. Refrigerant flow route 18b constitutes a final heat exchange portion 57. The heat exchange medium flowing out of first upstream tank 33 discharged from heat exchanger 50 through discharging route 42.
In the second embodiment of the present invention, similar to the function of the first embodiment, the pressure loss of the heat exchange medium in heat exchanger may be reduced or eliminated, and the occurrence of temperature differential of the air between heat transfer tubes constituting each heat exchange portion of heat exchanger 1 may be reduced or eliminated, In addition, heat exchange medium having a higher temperature flows into penultimate heat exchange portion 56 and final heat exchange portion 57. Nevertheless, the heat exchange medium having a lower temperature flows into second heat exchange portion 54 and first heat exchange portion 53 relatively adjacent to inlet port 44 is provided at the downstream side of the air flow direction A, i.e. at the back side of penultimate heat exchange portion 56 and final heat exchange portion 57. Consequently, the occurrence of temperature differential of the air passing through heat exchanger 1 may be suppressed or eliminated.
As described above, according to the embodiments of the present invention, if the heat exchanger is of thin profile, at least three heat exchange portions are provided. Therefore, while a cross-sectional area of the refrigerant route per one heat exchanger portion is ensured, the length of the refrigerant route in each tank in the longitudinal direction is reduced. Consequently, the pressure loss of the heat exchange medium flowing in the heat exchanger may be reduced or eliminated, and occurrence of the different temperature of the heat exchange medium between each heat transfer tube constituting each heat exchanger portion may be reduced or eliminated.

Claims

A heat exchanger (1, 50), the heat exchanger comprising:

a pair of first opposed tank portions, provided at a downstream side of air passing through said heat exchanger;

a pair of final opposed tank portions, provided at an upstream side of the air passing through said heat exchanger;

a first heat exchange portion (46), said first heat exchange portion being disposed at a downstream side of the air passing through said heat exchanger and having a first group of tubes, said first group of tubes extending between said pair of first opposed tank portions to form a first route (17, 17a) of a heat exchange medium; and

a final heat exchange portion (48), said final heat exchange portion being disposed at an upstream side of the air passing through said heat exchanger and at a back side of said first heat exchange portion, said final heat exchange portion having a final group of tubes, said final group of tubes extending between said pair of final opposed tank portions to form a final route (18, 18b) of said heat exchange medium,

characterised in that:

said heat exchanger further comprises:

a communicating heat exchange portion (47), which is disposed at both said upstream side and said downstream side of the air passing through said heat exchanger, said communicating heat exchange portion having a communicating group of tubes; and

a pair of opposed communicating tanks (35, 39), between which said communicating group of tubes extends to form a communicating route (28, 29) of said heat exchange medium; and

said first heat exchange portion (46) and said final heat exchange portion (48) are provided at a heat exchange medium inlet and outlet side, and said communicating heat exchange portion (47) is provided at a side opposite to said heat exchange medium inlet and outlet side.
A heat exchanger (1) according to claim 1, wherein:

said communicating heat exchange portion (47) is disposed adjacent to said first heat exchange portion (46) and said final heat exchange portion (48); and

the heat exchange flow route of said heat exchanger is formed of said first route (17) of said first heat exchange portion, said communicating route (28, 29) of said communicating heat exchange portion, and said final route (18) of said final heat exchange portion, in that order.
A heat exchanger (50) according to claim 1, the heat exchanger further comprising:

a pair of second opposed tank portions, provided at a downstream side of the air passing through said heat exchanger;

a pair of penultimate opposed tank portions, provided at an upstream side of the air passing through said heat exchanger;

a second heat exchange portion (54), said second heat exchange portion being disposed at a downstream side of the air passing through said heat exchanger and adjacent to said first heat exchange portion (46), said second heat exchange portion having a second group of tubes extending between said pair of second opposed tank portions to form a second route (17b) of said heat exchange medium; and

a penultimate heat exchange portion (56), said penultimate heat exchange portion being disposed at an upstream side of the air passing through said heat exchanger and at a back side of said second heat exchange portion, said penultimate heat exchange portion having a penultimate group of tubes extending between said pair of penultimate opposed tank portions to form a penultimate route (18a) of said heat exchange medium.
A heat exchanger (50) according to claim 3, wherein:

said communicating heat exchange portion (47) is disposed adjacent to said second heat exchange portion (54) and said penultimate heat exchange portion (56); and

the heat exchange flow route of said heat exchanger is formed of said first route (17a) of said first heat exchange portion (46), said second route (17b) of said second heat exchange portion, said communicating route (28, 29) of said communicating heat exchange portion, said penultimate route (18a) of said penultimate heat exchange portion, and said final route (18b) of said final heat exchange portion (48), in that order.