EP1519133A2

EP1519133A2 - Heat exchanging apparatus

Info

Publication number: EP1519133A2
Application number: EP04255603A
Authority: EP
Inventors: Takenori Sakamoto; Yusuke Iino
Original assignee: Sanden Corp
Current assignee: Sanden Corp
Priority date: 2003-09-29
Filing date: 2004-09-16
Publication date: 2005-03-30
Also published as: EP1519133A3; JP2005106328A; CN1629590A

Abstract

In a heat exchanging apparatus (1) disposing two heat exchangers (3,4) in a form of two rows of upstream downstream sides in an air flow direction (2), each heat exchanger (3,4) comprising a pair of header pipes (5a,6a,5b,6b), a plurality of heat transfer tubes (7a,7b) and corrugated-type fins (8a,8b) disposed between respective adjacent heat transfer tubes, an inlet (9) for a heat exchange medium is provided on the heat exchanger of the downstream side, an outlet (10) for the heat exchange medium is provided on the heat exchanger of the upstream side, and a pitch of the fins (8a) of the upstream-side heat exchanger (3) is set larger than a pitch of the fins (8b) of the downstream-side heat exchanger (4). A resistance against air passage as a whole of the apparatus can be reduced, while maintaining a desirable maximum amount of heat exchange as the total of the two rows.

Description

The present invention relates to a heat exchanging apparatus in which two heat exchangers are disposed in a form of two rows of an upstream side and a downstream side in an air flow direction and a heat exchange medium is flown between both heat exchangers in series, and more specifically to a heat exchanging apparatus suitable for a case requiring performances where, while a good heat exchange ability can be ensured as a whole of the apparatus, a resistance against air passing can be reduced, and the apparatus can be installed in a limited space such as a space for an air conditioner for vehicles.
A heat exchanging apparatus is known wherein two heat exchangers are disposed in a form of two rows of an upstream side and a downstream side in an air flow direction, and the flow of a heat exchange medium is divided into a form of two rows by flowing the heat exchange medium between both heat exchangers in series (for example, Japanese Patent 3,371,071). In the structure described in this Japanese Patent, two flat-tube type heat exchangers dividing the flow of heat exchange medium are disposed in a form of two rows of an upstream side and a downstream side in an air flow direction, although the flow area of a hole for passing the heat exchange medium of one heat transfer tube is set to be the same for both the upstream-side and downstream-side heat exchangers, the width of the heat transfer tube of the upstream-side heat exchanger is set larger than that of the downstream-side heat exchanger, and the number of the holes for passing the heat exchange medium in the upstream-side heat exchanger is set to be an even number and that in the downstream-side heat exchanger is set to be the number of the upstream-side heat exchanger minus 2. In this structure, paying attention to a fact in that, in a heat exchanging apparatus dividing a flow of heat exchange medium into a form of two rows, the heat exchange in the upstream-side heat transfer tubes in an air flow direction is performed more actively than that in the downstream-side heat transfer tubes, the amount of circulated heat exchange medium in the upstream-side heat transfer tubes is increased, thereby increasing the ability of the heat exchange as a whole of the apparatus.
On the other hand, a structure is disclosed in JP-A-4-73599, wherein, in a flat-tube type heat exchanger, the inside of a heat transfer tube is divided in an air flow direction into a flow path of an upstream side and a flow path of a downstream side different from each other, and on the contrary to the structure of the above-described Japanese Patent, the flow area of the downstream-side flow path is set larger than the flow area of the upstream-side flow path, the amounts of heat exchange of two-row flow paths are balanced by increasing the amount of the heat exchange medium circulated in the downstream-side flow path.
However, in such heat exchanging apparatuses dividing the flow of heat exchange medium into a form of two rows in an air flow direction, generally, as compared with a heat exchanger having a heat exchange medium flow in a form of a single row in an air flow direction, the thickness in the air flow direction increases, and the pressure loss against passing air increases. Further, in the structure of Japanese Patent 3,371,071, because the shapes of the heat transfer tubes become two types, the cost of molds, the administrative expenses and the number of manufacturing processes increase, thereby increasing the cost for manufacture.
Recently, the requirement for making a heat exchanger used in an air conditioner for vehicles smaller increases more and more, and at the same time, increase of the performance and efficiency of the air conditioning is required. For increase of the performance and efficiency of air conditioning, it is most desirable to increase the efficiency of a heat exchanger, but there is a limit therefor. Therefore, it is considered to increase the size of a heat exchanger in order to satisfy the requirements, but it is not so easy from the viewpoint of layout in vehicle. Accordingly, as the next best way, it may be considered to increase the thickness of a heat exchanger. In this case, considered are two methods of a method for merely increasing the thickness of a heat exchanger and a method for disposing two thin heat exchangers in a form of two rows in an air flow direction, and the latter method is considered to be more effective. In a case where two thin heat exchangers are merely disposed in a form of two rows, however, as compared with a case of a single row, the resistance against passing air increases two times. If the air passage resistance increases, for example, in a case of a condenser, there may be the following problems particularly at the time of a low vehicle speed (at the time during operation of a cooling fan, in particular, at the time of idling).
(1) A thermal damage may be given to a radiator generally disposed rearward a condenser.
(2) A thermal damage may be given to a condenser itself.
Accordingly, it would be desirable to, on the premise of a structure wherein two heat exchangers are disposed in a form of two rows in an air flow direction and a flow of heat exchange medium is divided in a form of two rows, provide a heat exchanging apparatus which can reduce the resistance in air passage against passing air as a whole of the apparatus, while maintaining a desirable maximum amount of heat exchange as the total of the two rows.
To accomplish the above-described subject, a heat exchanging apparatus according to the present invention disposing two heat exchangers in a form of two rows of an upstream side and a downstream side in an air flow direction, each heat exchanger comprising a pair of header pipes disposed to face each other, a plurality of heat transfer tubes respective ends of which communicate with respective corresponding header pipes and which are arranged in an axial direction of the header pipes at a predetermined interval, and corrugated-type fins disposed between respective adjacent heat transfer tubes each formed so as to have a predetermined pitch in a heat transfer tube extending direction, a heat exchange medium being flown between both heat exchangers in series, is characterized in that an inlet for the heat exchange medium is provided on the heat exchanger of the downstream side in the air flow direction, an outlet for the heat exchange medium is provided on the heat exchanger of the upstream side in the air flow direction, and a pitch of the fins of the heat exchanger of the upstream side in the air flow direction is set larger than a pitch of the fins of the heat exchanger of the downstream side in the air flow direction (the first aspect of the present invention). Namely, the pitches of the corrugated-type fins of the heat exchangers disposed in a form of two rows are differentiated from each other, the fin pitch of the upstream side is made larger (made coarse), and the fin pitch of the downstream side is made smaller (made dense).
In this heat exchanging apparatus, it is preferred that the ratio of the fin pitch of the heat exchanger of the upstream side in the air flow direction to the fin pitch of the heat exchanger of the downstream side in the air flow direction is set within a range of 1.1 to 1.3.
Further, another heat exchanging apparatus according to the present invention disposing two heat exchangers in a form of two rows of an upstream side and a downstream side in an air flow direction, each heat exchanger comprising a pair of header pipes disposed to face each other, a plurality of heat transfer tubes respective ends of which communicate with respective corresponding header pipes and which are arranged in an axial direction of the header pipes at a predetermined interval, corrugated-type fins disposed between respective adjacent heat transfer tubes each formed so as to have a predetermined pitch in a heat transfer tube extending direction, and a plurality of louvers arranged on each of the fins so as to have a predetermined pitch in the air flow direction, a heat exchange medium being flown between both heat exchangers in series, is characterized in that an inlet for the heat exchange medium is provided on the heat exchanger of the downstream side in the air flow direction, an outlet for the heat exchange medium is provided on the heat exchanger of the upstream side in the air flow direction, and a pitch of the louvers provided on the fins of the heat exchanger of the upstream side in the air flow direction is set larger than a pitch of the louvers provided on the fins of the heat exchanger of the downstream side in the air flow direction (the second aspect of the present invention). Namely, the pitches of the louvers provided on the fins of the heat exchangers disposed in a form of two rows are differentiated from each other, the louver pitch of the upstream side is made larger (made coarse), and the louver pitch of the downstream side is made smaller (made dense).
A further heat exchanging apparatus according to the present invention disposing two heat exchangers in a form of two rows of an upstream side and a downstream side in an air flow direction, each heat exchanger comprising a pair of header pipes disposed to face each other, a plurality of heat transfer tubes respective ends of which communicate with respective corresponding header pipes and which are arranged in an axial direction of the header pipes at a predetermined interval, corrugated-type fins disposed between respective adjacent heat transfer tubes each formed so as to have a predetermined pitch in a heat transfer tube extending direction, and a plurality of louvers arranged on each of said fins so as to have a predetermined pitch in the air flow direction, a heat exchange medium being flown between both heat exchangers in series, is characterized in that an inlet for the heat exchange medium is provided on the heat exchanger of the downstream side in the air flow direction, an outlet for the heat exchange medium is provided on the heat exchanger of the upstream side in the air flow direction, and a rise angle of the louvers provided on the fins of the heat exchanger of the upstream side in the air flow direction is set smaller than a rise angle of the louvers provided on the fins of the heat exchanger of the downstream side in the air flow direction (the third aspect of the present invention). Namely, the rise angle of the louvers provided on the fins of the heat exchangers disposed in a form of two rows are differentiated from each other, the louver rise angle of the upstream side is made smaller, and the louver rise angle of the downstream side is made larger.
A still further heat exchanging apparatus according to the present invention disposing two heat exchangers in a form of two rows of an upstream side and a downstream side in an air flow direction, each heat exchanger comprising a pair of header pipes disposed to face each other, a plurality of heat transfer tubes respective ends of which communicate with respective corresponding header pipes and which are arranged in an axial direction of said header pipes at a predetermined interval, corrugated-type fins disposed between respective adjacent heat transfer tubes each formed so as to have a predetermined pitch in a heat transfer tube extending direction, and a plurality of louvers arranged on each of the fins so as to have a predetermined pitch in the air flow direction, a heat exchange medium being flown between both heat exchangers in series, is characterized in that an inlet for the heat exchange medium is provided on the heat exchanger of the downstream side in the air flow direction, an outlet for the heat exchange medium is provided on the heat exchanger of the upstream side in the air flow direction, and at least two structures among the following structures (A) to (C) are provided;
(A) a structure wherein a pitch of the fins of the heat exchanger of the upstream side in the air flow direction is set larger than a pitch of the fins of the heat exchanger of the downstream side in the air flow direction,
(B) a structure wherein a pitch of the louvers provided on the fins of the heat exchanger of the upstream side in the air flow direction is set larger than a pitch of the louvers provided on said fins of the heat exchanger of the downstream side in the air flow direction, and
(C) a structure wherein a rise angle of the louvers provided on the fins of the heat exchanger of the upstream side in the air flow direction is set smaller than a rise angle of the louvers provided on the fins of the heat exchanger of the downstream side in the air flow direction.
In such heat exchanging apparatuses according to the present invention, by providing an inlet for the heat exchange medium on the heat exchanger of the downstream side in the air flow direction, providing an outlet for the heat exchange medium on the heat exchanger of the upstream side in the air flow direction and flowing the heat exchange medium between both heat exchangers in series, it becomes possible to obtain a desirable amount of heat exchange as the total of the two rows. Then, in the first aspect of the present invention, by making the fin pitch of the upstream side in the air flow direction coarse and making the fin pitch of the downstream side dense, it becomes possible to reduce the resistance against air passage (the pressure loss at the time of passing air) as a whole of the apparatus, while maintaining the desirable amount of heat exchange as the total of the two rows. In particular, at the time of a low vehicle speed, as shown in a comparison in performance described later, it becomes possible to reduce the resistance against air passage, while maintaining a heat exchange performance equal to that of a case where the fin pitch ratio of the upstream side to the downstream side in the air flow direction is 1:1.
Further, in the second aspect of the present invention, by making the louver pitch of the upstream side in the air flow direction coarse and making the louver pitch of the downstream side dense, it becomes possible to reduce the resistance against air passage as a whole of the apparatus, while maintaining the desirable amount of heat exchange as the total of the two rows. Furthermore, in the third aspect of the present invention, by making the louver rise angle of the upstream side in the air flow direction smaller and making the louver rise angle of the downstream side larger, it becomes possible to reduce the resistance against air passage as a whole of the apparatus, while maintaining the desirable amount of heat exchange as the total of the two rows. Moreover, for example, in a case where any of these first, second and third aspects of the present invention is restricted in design, it is possible to appropriately combine two or more of these aspects. Even in such a combination aspect, it becomes possible to reduce the resistance against air passage as a whole of the apparatus, while maintaining the desirable amount of heat exchange as the total of the two rows.
Thus, in the heat exchanging apparatus according to the present invention, in the formation where two heat exchangers are disposed in a form of two rows in an air flow direction, while maintaining a desirable amount of heat exchange as the total of the two rows, reduction of a resistance against air passage as a whole of the apparatus can be achieved. In particular, in a case where the present invention is applied to an air conditioner for vehicles, it is possible to effectively exhibit this improved performance at the time of a low vehicle speed. Especially, in a case where the present invention is applied to a condenser, it becomes possible to solve the aforementioned problems of a thermal damage to a radiator and a thermal damage to the condenser itself.
Further objects, features, and advantages of the present invention will be understood from the following detailed description of the preferred embodiments of the present invention with reference to the accompanying figures.
Embodiments of the invention are now described with reference to the accompanying figures, which are given by way of example only, and are not intended to limit the present invention.
Fig. 1 is a perspective view of a heat exchanging apparatus according to a first embodiment of the present invention.
Fig. 2 is a schematic diagram showing a flow of a heat exchange medium in the heat exchanging apparatus depicted in Fig. 1.
Fig. 3 is a graph showing a relationship between a front wind speed Vc and a resistance against air passage Pa in a case where a fin pitch of a heat exchanger of the upstream side is changed relative to a fin pitch of a heat exchanger of the downstream side in the heat exchanging apparatus depicted in Fig. 1.
Fig. 4 is a graph showing a relationship between a front wind speed Vc and a heat exchange performance Qc in a case where a fin pitch of a heat exchanger of the upstream side is changed relative to a fin pitch of a heat exchanger of the downstream side in the heat exchanging apparatus depicted in Fig. 1.
Fig. 5 is a graph showing a relationship between a resistance against air passage Pa and a heat exchange performance Qc in a case where a fin pitch of a heat exchanger of the upstream side is changed relative to a fin pitch of a heat exchanger of the downstream side in the heat exchanging apparatus depicted in Fig. 1.
Fig. 6 is a side view of a heat exchanging apparatus according to a second embodiment of the present invention, showing a state for providing louvers on fins of a heat exchanger of the upstream side and on fins of a heat exchanger of the downstream side.
Fig. 7 is a partial, enlarged sectional view of a heat exchanging apparatus according to a third embodiment of the present invention.
Figs. 1 and 2 show a heat exchanging apparatus 1 according to a first embodiment of the present invention. This first embodiment corresponds to the aforementioned first aspect of the present invention. Heat exchanging apparatus 1 has two heat exchangers disposed in a form of two rows of an upstream side and a downstream side in a direction of an air flow 2, which comprise an upstream-side heat exchanger 3 and a downstream-side heat exchanger 4. Respective heat exchangers 3 and 4 comprise a pair of header pipes 5a, 6a and 5b, 6b disposed to face each other, a plurality of heat transfer tubes 7a, 7b respective ends of which communicate with respective corresponding header pipes 5a, 6a and 5b, 6b and which are arranged in an axial direction of the header pipes 5a, 6a and 5b, 6b at a predetermined interval, and corrugated-type fins 8a, 8b disposed between respective adjacent heat transfer tubes 7a, 7b each formed so as to have a predetermined pitch in an extending direction of the adjacent heat transfer tubes 7a, 7b. In heat exchangers 3, 4 disposed in a form of two rows, an inlet 9 for heat exchange medium is provided on header pipe 6b of heat exchanger 4 of the downstream side in the air flow direction, and an outlet 10 for the heat exchange medium is provided on header pipe 6a of heat exchanger 3 of the upstream side in the air flow direction. The heat exchange medium having passed through the inside of heat exchanger 4 flows into header pipe 5a of heat exchanger 3 of the upstream side from header pipe 5b through a connection pipe 11, and flows from heat exchanger 4 to heat exchanger 3 in series.
In such a heat exchanging apparatus 1, in this embodiment, a pitch of fins 8a of heat exchanger 3 of the upstream side in the air flow direction is set larger than a pitch of fins 8b of heat exchanger 4 of the downstream side in the air flow direction. Namely, the pitch of fins 8a ofthe upstream side is made relatively coarse, and the pitch of fins 8b of the downstream side is made relatively dense.
In the above-described heat exchanging apparatus 1, by disposing heat exchangers 3, 4 in a form of two rows of upstream and downstream sides in the air flow direction and flowing the heat exchange medium from heat exchanger 4 to heat exchanger 3 in series, a desirable amount of heat exchange can be ensured as a whole of the apparatus. Further, while this desirable amount of heat exchange is ensured, the resistance against air passage as a whole of the apparatus can be suppressed small.
The performance of this heat exchanging apparatus 1 will be explained in reference to Figs. 3 to 5, comparing with a case where a fin pitch of the upstream side (front row) and a fin pitch of the downstream side (rear row) are set as a same pitch (that is, 1:1). Fig. 3 shows a diagram of resistance against air passage, and shows a relationship between a front wind speed Vc (that is, a speed of air flowing into heat exchanger 3) and a resistance against air passage Pa in heat exchanging apparatus 1 with respect to cases of the ratios of front-side fin pitch to rear-side fin pitch of 1:1, 1.15:1, and 1.25:1.
Further, Figs 4 and 5 show diagrams of heat exchange performance. Fig. 4 shows a relationship between a front wind speed Vc and a heat exchange performance Qc, and Fig. 5 shows a relationship between a resistance against air passage Pa and a heat exchange performance Qc, with respect to cases of the ratios of front-side fin pitch to rear-side fin pitch of 1:1, 1.15: 1, and 1.25:1, respectively.
As is evident from Fig. 3, in the cases in fin pitch of 1.15: 1 and 1.25:1, as compared with a case of fin pitch of 1:1, the resistance against air passage Pa is reduced in the entire front-wind speed region (that is, the entire vehicle-speed range). Further, as is evident from Fig. 4, in the cases in fin pitch of 1.15: 1 and 1.25:1, as compared with a case of fin pitch of 1:1, when the front wind speed Vc becomes great, although the heat exchange performance Qc per the front wind speed is slightly poor, when the front wind speed is small (for example, at the time of idling), almost the same level of heat exchange performance Qc can be exhibited. Moreover, as is evident from Fig. 5, in the cases in fin pitch of 1.15: 1 and 1.25:1, as compared with a case of fin pitch of 1:1, the heat exchange performance Qc per the resistance against air passage can be increased over the entire region of resistance against air passage.
Namely, in the heat exchanging apparatus 1 according to the first embodiment, while a desirable maximum amount of heat exchange as the total of the two rows of heat exchangers 3 and 4 is maintained, the resistance against air passage as a whole of the apparatus 1 can be reduced. Further, when the heat exchanging apparatus 1 is applied to an air conditioner for vehicles, the improved performance can be exhibited at the time of a low-speed running, at the time of idling, etc. In particular, if the present invention is applied to a condenser, the aforementioned problems such as a thermal damage to a radiator or a thermal damage to the condenser itself can be solved.
Fig. 6 shows a heat exchanging apparatus 12 according to a second embodiment of the present invention, and this second embodiment corresponds to the aforementioned second aspect of the present invention. Heat exchanging apparatus 12 has a heat exchanger 13 disposed at an upstream side in the direction of air flow 2 and a heat exchanger 14 disposed at a downstream side. Respective heat exchangers 13 and 14 comprise a plurality of heat transfer tubes 15a, 15b arranged in an axial direction of header pipes (not shown) at a predetermined interval, and corrugated- type fins 16a, 16b disposed between respective adjacent heat transfer tubes 15a, 15b. The other structures such as the inlet and outlet for heat exchange medium are substantially the same as those shown in Figs. 1 and 2.
A plurality of louvers 17a, 17b are disposed on respective fins 16a, 16b at a predetermined interval along the direction of air flow 2. Further, in this embodiment, a pitch of louvers 17a of heat exchanger 13 of the upstream side in the air flow direction is set larger than a pitch of louvers 17b of heat exchanger 14 of the downstream side in the air flow direction. Namely, the pitch of louvers 17a of the upstream side is made relatively coarse, and the pitch of louvers 17b of the downstream side is made relatively dense.
Also in this embodiment, by disposing heat exchangers 13, 14 in a form of two rows of upstream and downstream sides in the direction of air flow 2 and flowing the heat exchange medium from heat exchanger 14 to heat exchanger 13 in series, a desirable amount of heat exchange can be ensured as a whole of the apparatus 12. Further, in this embodiment, since the pitch of louvers 17a of the upstream side is set coarse and the pitch of louvers 17b of the downstream side is set dense, a pressure loss at an entrance for air of the apparatus 12 is reduced, and a resistance against air passage as a whole of the apparatus 12 can be reduced. Furthermore, when the heat exchanging apparatus 12 is applied to an air conditioner for vehicles, the improved performance can be exhibited at the time of a low-speed running, at the time of idling, etc. In particular, if the present invention is applied to a condenser, the aforementioned problems such as a thermal damage to a radiator or a thermal damage to the condenser itself can be solved.
Fig. 7 shows sections of a fin 18a of an upstream side and a fin 18b of a downstream side in the direction of air flow 2 according to a third embodiment of the present invention. This embodiment corresponds to the aforementioned third aspect of the present invention. Louvers 19a, 19b are provided on fins 18a and 18b, respectively. The other structures are substantially the same as those shown in Figs. 1 and 2.
Although the number of upstream-side louvers 19a is the same as that of downstream-side louvers 19b, in this embodiment, the rise angles of both louvers are different from each other. Namely, as shown in Fig. 7, a rise angle α of louvers 19a provided on upstream-side fin 18a in the direction of air flow 2 is set smaller than a rise angle β of louvers 19b provided on downstream-side fin 18b in the direction of air flow 2 (that is, α < β).
Also in this embodiment, by disposing two heat exchangers in a form of two rows of upstream and downstream sides in the direction of air flow 2 and flowing the heat exchange medium from the downstream-side heat exchanger to the upstream-side heat exchanger in series, a desirable amount of heat exchange can be ensured as a whole of the apparatus. Further, in this embodiment, since the rise angle α of upstream-side louvers 19a is set smaller than a rise angle β of downstream-side louvers 19b, a resistance against air passage as a whole of the apparatus can be reduced.
In the above-described first through third embodiments, although the object of the present invention, namely, to reduce a resistance against air passage as a whole of an apparatus while maintaining a desirable amount of heat exchange of the total of the two rows, can be achieved even when a sole embodiment is applied, it is possible to appropriately combine two or more embodiments, and in such a combination, the object of the present invention can be achieved more effectively. Further, even in a case where any embodiment cannot be carried out from a reason such as restriction in design, by appropriately combining the other embodiments, the object of the present invention can be surely achieved.
The present invention can be applied to a heat exchanging apparatus disposing heat exchangers in a form of two rows in an air flow direction and flowing a heat exchange medium in series, and in particular, the present invention is suitable as a heat exchanging apparatus for a refrigeration system used in an air conditioner for vehicles.

Claims

A heat exchanging apparatus disposing two heat exchangers in a form of two rows of an upstream side and a downstream side in an air flow direction, each heat exchanger comprising a pair of header pipes disposed to face each other, a plurality of heat transfer tubes respective ends of which communicate with respective corresponding header pipes and which are arranged in an axial direction of said header pipes at a predetermined interval, and corrugated-type fins disposed between respective adjacent heat transfer tubes each formed so as to have a predetermined pitch in a heat transfer tube extending direction, a heat exchange medium being flown between both heat exchangers in series, characterized in that an inlet for said heat exchange medium is provided on said heat exchanger of the downstream side in said air flow direction, an outlet for said heat exchange medium is provided on said heat exchanger of the upstream side in said air flow direction, and a pitch of said fins of said heat exchanger of the upstream side in said air flow direction is set larger than a pitch of said fins of said heat exchanger of the downstream side in said air flow direction.
A heat exchanging apparatus disposing two heat exchangers in a form of two rows of an upstream side and a downstream side in an air flow direction, each heat exchanger comprising a pair of header pipes disposed to face each other, a plurality of heat transfer tubes respective ends of which communicate with respective corresponding header pipes and which are arranged in an axial direction of said header pipes at a predetermined interval, corrugated-type fins disposed between respective adjacent heat transfer tubes each formed so as to have a predetermined pitch in a heat transfer tube extending direction, and a plurality of louvers arranged on each of said fins so as to have a predetermined pitch in said air flow direction, a heat exchange medium being flown between both heat exchangers in series, characterized in that an inlet for said heat exchange medium is provided on said heat exchanger of the downstream side in said air flow direction, an outlet for said heat exchange medium is provided on said heat exchanger of the upstream side in said air flow direction, and a pitch of said louvers provided on said fins of said heat exchanger of the upstream side in said air flow direction is set larger than a pitch of said louvers provided on said fins of said he at exchanger of the downstream side in said air flow direction.
A heat exchanging apparatus disposing two heat exchangers in a form of two rows of an upstream side and a downstream side in an air flow direction, each heat exchanger comprising a pair of header pipes disposed to face each other, a plurality of heat transfer tubes respective ends of which communicate with respective corresponding header pipes and which are arranged in an axial direction of said header pipes at a predetermined interval, corrugated-type fins disposed between respective adjacent heat transfer tubes each formed so as to have a predetermined pitch in a heat transfer tube extending direction, and a plurality of louvers arranged on each of said fins so as to have a predetermined pitch in said air flow direction, a heat exchange medium being flown between both heat exchangers in series, characterized in that an inlet for said heat exchange medium is provided on said heat exchanger of the downstream side in said air flow direction, an outlet for said heat exchange medium is provided on said heat exchanger of the upstream side in said air flow direction, and a rise angle of said louvers provided on said fins of said heat exchanger of the upstream side in said air flow direction is set smaller than a rise angle of said louvers provided on said fins of said heat exchanger of the downstream side in said air flow direction.
A heat exchanging apparatus disposing two heat exchangers in a form of two rows of an upstream side and a downstream side in an air flow direction, each heat exchanger comprising a pair of header pipes disposed to face each other, a plurality of heat transfer tubes respective ends of which communicate with respective corresponding header pipes and which are arranged in an axial direction of said header pipes at a predetermined interval, corrugated-type fins disposed between respective adjacent heat transfer tubes each formed so as to have a predetermined pitch in a heat transfer tube extending direction, and a plurality of louvers arranged on each of said fins so as to have a predetermined pitch in said air flow direction, a heat exchange medium being flown between both heat exchangers in series, characterized in that an inlet for said heat exchange medium is provided on said heat exchanger of the downstream side in said air flow direction, an outlet for said heat exchange medium is provided on said heat exchanger of the upstream side in said air flow direction, and at least two structures among the following structures (A) to (C) are provided;

(A) a structure wherein a pitch of said fins of said heat exchanger of the upstream side in said air flow direction is set larger than a pitch of said fins of said heat exchanger of the downstream side in said air flow direction,

(B) a structure wherein a pitch of said louvers provided on said fins of said heat exchanger of the upstream side in said air flow direction is set larger than a pitch of said louvers provided on said fins of said heat exchanger of the downstream side in said air flow direction, and

(C) a structure wherein a rise angle of said louvers provided on said fins of said heat exchanger of the upstream side in said air flow direction is set smaller than a rise angle of said louvers provided on said fins of said heat exchanger of the downstream side in said air flow direction.