EP1167910B1

EP1167910B1 - Condenser

Info

Publication number: EP1167910B1
Application number: EP01115028A
Authority: EP
Inventors: Manaka Oyama Regional Office Hideaki
Original assignee: Showa Denko KK
Current assignee: Resonac Holdings Corp
Priority date: 2000-06-20
Filing date: 2001-06-20
Publication date: 2006-02-01
Anticipated expiration: 2021-06-20
Also published as: ES2257360T3; ATE317100T1; EP1167910A3; EP1167910A2; US20020007646A1; DE60116922D1; DE60116922T2

Abstract

A condenser includes a pair of headers (11) and a plurality of heat exchanging tubes (12) disposed between the headers (11) with their opposite ends connected to the headers (11). The plurality of heat exchanging tubes (12) are grouped into three paths P1-P3 by partitions (16). A refrigerant introduced from a refrigerant inlet 11a provided at the lower portion of one of headers passes upwardly through the paths P1-P3 in sequence, and flows out of a refrigerant outlet 11b provided at an upper portion of one of headers. The cross-sectional area of each path decreases stepwise towards a downstream side path, and the reduction rate of the cross-sectional are of the downstream side path of the adjacent two paths to the cross-sectional area of the upstream side path thereof is set to 20%. Thereby, the cooling performance can be achieved. <IMAGE>

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a use of a condenser and to a refrigeration System for, for example, car air-conditioners.

2. Description of Related Art

As shown in Fig. 8, a conventional multi-flow type condenser for use in car air-conditioners includes a pair of vertical headers 1 and 1 disposed apart from each other and a plurality of horizontal flat tubes 2 as heat exchanging tubes disposed between the headers at certain intervals in the direction of up-and-down with their opposite ends connected with the headers. One of the headers 1 is provided with a refrigerant inlet 1a at the upper end portion thereof, and the other header 1 is provided with a refrigerant outlet 1b at the lower portion thereof. Furthermore, the headers 1 are provided with partitions 5 each disposed at a predetermined portion for dividing the inside of the header to thereby group the aforementioned plurality of flat tubes 2 into a plurality of paths P1 to P3.
Thus, in this condenser, the refrigerant introduced from the refrigerant inlet 1a passes downwardly through each path P1 to P3 in sequence in a meandering manner, and then flows out of the refrigerant outlet 1b. During passing through these paths, the refrigerant exchanges heat with the ambient air to be condensed into a liquefied refrigerant.
The inventors of the present application analyzed the stagnation of the liquefied refrigerant in the aforementioned condenser by using a thermography. According to the results of the analysis, as shown in Figs. 9 and 10, the liquefied refrigerant RL tends to stagnate at the downstream lower portion in each path P1-P3. In detail, in the conventional condenser, the liquefaction of refrigerant has already started at the end portion in the first path P1. Therefore, the liquefied refrigerant RL stays at the bottom of the header portion connecting the first and second paths P1 and P2, which may cause the so-called liquid stagnation. Since this stagnated liquefied refrigerant RL blockades the tube-inlets of the lower portion of the second path P2, only the liquefied refrigerant RL flows into the lower tubes 2 of the second path P2. Similarly, only the liquefied refrigerant RL flows into the lower tubes 2 of the third path P3. Since those portions through which only the liquefied refrigerant RL flows cannot perform efficient heat exchanging, an effective heat transfer area decreases, which causes deterioration in the refrigeration performance.
Furthermore, the liquefied refrigerant RL impedes the refrigerant circulation, resulting in an increased refrigerant flow resistance.
US 6,021,846 discloses a duplex heat exchanger comprising: a plurality of unit heat exchangers; each of the unit heat exchangers having a circuit formed therethrough for a heat exchanging medium; and a connecting means for connecting the circuits in fluid communication with each other, each of the unit heat exchangers comprising: a plurality of tubes arranged in parallel with each other; and a pair of hollow headers to which both ends of each tube are connected in fluid communication, wherein the unit heat exchangers are arranged fore and aft in a direction of air flow so that one of said unit heat exchangers faces windward, with the other said unit exchangers lying leeward, wherein the circuits formed through the unit heat exchangers for the heat exchanging medium are connected in parallel with one another.
US 5,730,212 discloses a refrigerant condenser for use in a vehicle air-conditioner, comprising a pair of headers which form an inlet and an outlet for refrigerant and which are connected by a plurality of tubes, wherein the number of turns may be set to 2 by means of separators, wherein the tubes may be set to a combination of 11, 11, and 10 or 16, 12, and 4.
US 6,062,303 discloses a multiflow type condenser comprising a pair of header pipes disposed in parallel with each other and arranged to have an inlet and an outlet; a plurality of tubes each connected to said header pipes at opposite ends thereof, at least a pair of baffles disposed in said header pipes; and an area of a pass on the inlet side defined by the chamber on the inlet side of the chambers divided by the baffles, into which the refrigerant is introduced through said inlet and formed in one of the header pipes, the opposed chamber formed in the other of the header pipes, and a plurality of tubes extending between the chambers is about 30% to 65% of an overall area of all of the passes.
US 5,482,112 discloses a condenser comprising a plurality of tubular elements defining flow paths, and a pair of headers disposed at opposite ends of the tubular elements, the one/or the other header defining a coolant inlet and a coolant outlet, wherein both headers are divided in two sections by means of a partition to divide the whole coolant path into an inlet side group, an intermediate group and an outlet side group, and wherein the intermediate group has a cross-sectional area smaller that that of the inlet side group and greater than that of the outlet side group.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a condenser use and refrigeration system, having a decreased refrigerant flow resistance and an improved cooling performance.
This is achieved by the subject matters having the features in claim 1 and claim 3, respectively.
With this condenser, the gaseous refrigerant flowed out of the heat exchanging tubes constituting the upstream side path (lower side path) goes up vigorously in the refrigerant turning portion of the header connecting the adjacent paths, and the rising refrigerant flows into the heat exchanging tubes constituting the downstream side path (upper side path). Thus, the liquefied refrigerant is pushed up by the blow-up effect of this rising refrigerant, and flows into the heat exchanging tubes constituting the downstream side path (upper side path) smoothly. This prevents a stagnation of the liquefied refrigerant, which keeps a large effective heat transferring area of the heat exchanging portion and enables an equally distributed smooth refrigerant flow in each path.
According to the invention, the plurality of paths includes three or more paths including a first path, a second path and a third path through which the refrigerant introduced from the refrigerant inlet passes in sequence, a reduction rate of a cross-sectional area of the second path to a cross-sectional area of the first path is 50% or more, and a reduction rate of a cross-sectional area of the third path to a cross-sectional area of the second path is 40% or more. This has the effect that the aforementioned refrigerant blow-up effect by the refrigerant turning portion connecting the adjacent paths can fully be obtained, which can assuredly prevent the stagnation of the liquefied refrigerant in the refrigerant turning portion.
Further embodiments of the invention are described in dependent claims 2 and 4.
Other objects and the features will be apparent from the following detailed description of the present invention with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more fully described and better understood from the following description, taken with the appended drawings, in which:
Fig. 1 is a front view showing a condenser for use in car air-conditioners according to an embodiment of the present invention;
Fig. 2 is a schematic front view showing a refrigerant circuit arrangement of the condenser according to the embodiment:
Fig. 3 is an enlarged cross-sectional view showing a first refrigerant turning portion and therearound of the condenser according to the embodiment;
Fig. 4 is a schematic cross-sectional view showing a refrigerant circuit arrangement of a condenser for use in car air-conditioners according to a second embodiment of the present invention;
Fig. 5 is a schematic cross-sectional view showing a refrigerant circuit arrangement of a condenser for use in car air-conditioners according to a third embodiment of the present invention;
Fig. 6 is a schematic cross-sectional view showing a refrigerant circuit arrangement of a condenser for use in car air-conditioners according to a comparative example;
Fig. 7 is a graph showing a relationship between a refrigerant flow resistance and a refrigerant circulation amount of the inventive and comparative condensers;
Fig. 8 is a partially omitted front view showing a conventional condenser for use in car air-conditioners;
Fig. 9 is a schematic front view showing a refrigerant circuit arrangement of the conventional condenser; and
Fig. 10 is a schematic cross-sectional view showing a first refrigerant turning portion and therearound of the conventional condenser.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figs. 1 and 2 show a multi-flow type condenser for use in car air-conditioners according to an embodiment of the present invention.
As shown in these figures, this condenser has a pair of right and left headers 11 and 11 disposed at a certain distance. Between these headers 11 and 11, a plurality of flat tubes 12 as heat exchanging tubes are horizontally disposed at certain intervals in the vertical direction with their opposites ends connected to the headers 11 and 11. Furthermore, corrugated fins 13 are arranged between adjacent flat tubes 12 and disposed on the outermost flat tubes 12. Furthermore, on the outside of each outermost corrugated fin 13, a belt-shaped side plate 14 is disposed for protecting the outermost corrugated fin 13.
At the lower side of one of headers 11 (right header), a refrigerant inlet 11a is provided. On the other hand, at the upper side of the other header 11 (left header), a refrigerant outlet 11b is provided.
Furthermore, at a predetermined portion of each header 11, a partition 16 which divides the interior of the header 11 in the longitudinal direction thereof is provided, to thereby group the aforementioned plurality of flat tubes 12 into three paths, the first path P1 (lowermost path), the second path P2 (middle path) and the third path P3 (uppermost path).
The header portion of the left header 11 which connects the first path P1 with the second paths P1 and P2 constitutes a first refrigerant turning portion T1, and the header portion of the right header 11 which connects the second P2 with the third paths P3 constitutes a second refrigerant turning portion T2.
In the aforementioned embodiment, although the header portion constituting the turning portion T1 or T2 is formed by dividing a single cylindrical header 11 with partition 16, the present invention is not limited to this. For example, each header portion constituting the turning portion T1 and T2 may be formed by a separate individual header pipe.
In this embodiment, each path P1-P3 is decreased in cross-sectional area stepwise towards the downstream side path (upper side path) for each path. In the present invention, the reduction rate of the cross-sectional area of the downstream side path (upper side path) of the two adjacent paths to the upstream side path (lower side path) thereof should be set to 20% or more, and it is preferable that the reduction rate is set to 30% or more. The aforementioned reduction rate (%) can be obtained by the following formula: (1-PL/PU)×100(%), where "PU" is a cross-sectional area of the upstream side path and "PL" is that of the downstream side path. If the aforementioned reduction rate is smaller than 20%, an enough flow velocity (vigor) of the refrigerant cannot fully be secured in the refrigerant turning portion T1 and T2 in the header 11 between the adjacent paths, resulting in an inefficient refrigerant blow-up effect, which in turn may cause a liquefied refrigerant stagnation.
In the present invention, it is preferably that the aforementioned reduction rate is set to 25% or more in any two adjacent paths. It is more preferable that the reduction rate of the cross-sectional area of the second path to the cross-sectional area of the first path is 50% or more and that the reduction rate of the cross-sectional area of the third path to the cross-sectional area of the second path is 40% or more.
In the condenser of this embodiment, all of the flat tubes 12 have the same structure, and therefore the cross-sectional area of each path P1-P3 is in proportion to the number of tubes of each path P1-P3. Therefore, the reduction rate of the cross-sectional area between adjacent paths corresponds to the reduction rate of the number of tubes between the adjacent paths. In the condenser of this embodiment, as shown in Fig. 2, the first path P1 includes 22 flat tubes, the second path P2 includes 9 flat tubes and the third path P3 includes 5 flat tubes. Accordingly, the reduction rate of the cross-sectional areas between the first and second paths P1 and P2 is 59.1%, and that between the second and third paths P2 and P3 is 44.4%.
In the present invention, however, the reduction rate of the cross-sectional areas between adjacent paths may be set such that each path is constituted by the same number of tubes having different cross-sectional area.
In the present invention, although the total number of the paths is not especially limited, it is preferable that the total number is set to 2 to 5, more preferably 3 or 4. The most suitable total number is 3. If the total number of paths is set too much, the reduction rate of the cross-sectional areas between adjacent paths, i.e., the reduction rate of the tube number between the adjacent paths in the aforementioned embodiment, becomes too small, which causes a trouble in securing the aforementioned reduction rate. Thus, an effective refrigerant blow-up effect may not be obtained.
Furthermore, in the present invention, it is preferable that the cross-sectional area of each path is decreased stepwise for every path towards the downstream side (upper side). However, the heat exchange core may include adjacent paths each having the same cross-sectional area. Therefore, it should be understood that the present invention covers such a condenser including adjacent paths each having the same cross-sectional area, unless otherwise clearly defined.
Returning to the condenser of the aforementioned embodiment, the refrigerant introduced from the refrigerant inlet 11a passes upwardly through the first to third paths P1-P3 in sequence in a meandering manner, and flows out of the refrigerant outlet 11b. While passing through these paths, the refrigerant exchanges heat with the ambient air to be gradually condensed and liquefied.
At this time, the liquefaction of the gaseous refrigerant introduced from the refrigerant inlet 11a starts at the end portion of the first path P1, for example, and the liquefied refrigerant RL flows out of the tube-outlets of the first path P1 and tends to flow downwards in the first refrigerant turning portion T1, as shown in Fig 3. On the other hand, the gaseous refrigerant RG flows out of the tube-outlets of the first path P1, and goes up vigorously in the first turning portion T1. This rising gaseous refrigerant RG pushes up the aforementioned liquefied refrigerant RL. Thus, the liquefied refrigerant RL goes up in the first refrigerant turning portion T1 together with the gaseous refrigerant RG, and this rising mixture of refrigerant will be evenly distributed into each flat tube 12 constituting the second path P2 smoothly.
In this embodiment, since the cross-sectional area of the second path P2 is set to the aforementioned specific reduction rate to that of the first path P1, the flow velocity of the gaseous refrigerant rising in the first refrigerant turning portion T1 between the first and second paths P1 and P2 can be secured enough. Therefore, a sufficient blow-up effect in the refrigerant turning portion T1 can be obtained by the rising refrigerant, which in turn can prevent assuredly the stagnation of the liquefied refrigerant RL in the bottom portion of the refrigerant turning portion T1.
Regarding the refrigerant which will flow into the third path P3 through the second refrigerant turning portion T2 from the second path P2, a similar phenomenon can be observed. The gaseous refrigerant RG which goes up vigorously in the second refrigerant turning portion T2 will push up the liquefied refrigerant RL which tends to flow down, and therefore this rising refrigerant can flow into each flat tube 12 constituting the third path P3 smoothly. As a result, a liquid stagnation by the liquefied refrigerant can be prevented.
Thus according to the condenser of this embodiment, since a stagnation of the liquefied refrigerant can be prevented, the whole core surface can be used effectively as a heat exchanging portion, resulting in an improved cooling performance.
Furthermore, since the refrigerant will not stagnate and will pass through the whole region of each path in an evenly distributed manner, the refrigerant flow resistance can be reduced, resulting in a further enhanced heat exchanging performance.
Next, examples according to the present invention and a comparative example will be explained.

A condenser was manufactured in accordance with the aforementioned embodiment shown in Figs. 1 and 2. This condenser has three paths, i.e., the lowermost first path P1, the middle second path P2 and the uppermost third path P3. The first, second and third paths P1, P2 and P3 include twenty-two (22) tubes, nine (9) tubes and five (5) tubes, respectively. In this condenser, the reduction rate of the cross-sectional area of the second path P2 to that of the first path P1 is 59.1%, and the reduction rate of the cross-sectional area of the third path P3 to that of the second path P2 is 44.4%

As shown in Fig. 4, a condenser having three paths, i.e., the lowermost first path P1, the middle second path P2 and the uppermost third path P3, was manufactured. The first, second and third paths P1, P2 and P3 include eighteen (18) tubes, nine (9) tubes and five (5) tubes, respectively. Another structure is the same as the condenser of the first example. In this condenser, the reduction rate of the cross-sectional area of the second path P2 to that of the first path P1 is 50%, and the reduction rate of the cross-sectional area of the third path P3 to that of the second path P2 is 44.4%
In the second embodiment shown in Fig. 4, the same or corresponding reference numeral as in the first example are allotted to the same portion or corresponding portion (Similarly, the same or corresponding reference numeral will be allotted in the following third example shown in Fig. 5 and the following comparative example shown in Fig. 6).

As shown in Fig. 5, a condenser having four paths, i.e., the lowermost first path P1, the lower middle second path P2, the upper middle third path P3 and the uppermost fourth path P4, was manufactured. The first, second, third and fourth paths P1, P2, P3 and P4 include thirteen (13) tubes, nine (9) tubes, six (6) tubes and four (4) tubes, respectively. Another structure is the same as the condenser of the first example. In this condenser, the reduction rate of the cross-sectional area of the second path P2 to that of the first path P1 is 30.8%, the reduction rate of the cross-sectional area of the third path P3 to that of the second path P2 is 33.3% and the reduction rate of the cross-sectional area of the fourth path P4 to that of the third path P3 is 33.3%. In Fig. 5, the reference numeral T4 denotes a fourth refrigerant turning portion (the same numeral will be used in Fig. 6)

As shown in Fig. 6, a condenser having four paths, i.e., the uppermost first path P1, the upper middle second path P2, the lower middle third path P3 and the lowermost fourth path P4, was manufactured. The first, second, third and fourth paths P1, P2, P3 and P4 include thirteen (13) tubes, nine (9) tubes, six (6) tubes and four (4) tubes, respectively. Another structure is the same as the condenser of the first example. This condenser according to the comparative example has a symmetrical configuration rotated by 180 degrees to the aforementioned condenser according to the third example. Accordingly, in this condenser, the reduction rate of the cross-sectional area of the second path P2 to that of the first path P1 is 30.8%, the reduction rate of the cross-sectional area of the third path P3 to that of the second path P2 is 33.3% and the reduction rate of the cross-sectional area of the fourth path P4 to that of the third path P3 is 33.3%.

In the aforementioned examples and comparative example, it was observed whether or not a liquefied refrigerant (low-temperature refrigerant) stagnates based on the temperature distribution of a thermography image. According to the observation, in the condensers of the first to third examples, the refrigerant temperature decreased gradually towards the downstream portion in each path, there was no variation in temperature distribution, and no stagnation of a liquefied refrigerant was observed. Furthermore, in the condenser according to the comparative example, a low-temperature region existed in the lower portion in each path, and a stagnation of the liquefied refrigerant was observed in the lower portion.

The relation between the refrigerant flow resistance (kPa) and the refrigerant circulation amount (kg/h) in each condenser of the aforementioned examples and comparative example were measured. The measured results are shown in the graph of Fig. 7. In this graph, "A1," "A2," and "A3" denote the first, second and third examples, respectively, and "B" denotes the comparative example.
As will be apparent from this graph, in the condenser according to the first to third examples A1-A3, the refrigerant flow resistance to a predetermined refrigerant circulation amount was decreased as compared with the condenser according to the comparative example.
Among these three examples, especially the first and second examples A1 and A2 were able to reduce flow resistance remarkably. The reason is considered as follows: since the reduction rate of the cross-sectional area of the second path P2 to the cross-sectional area of the first path P1 is set to 50% or more and the reduction rate of the cross-sectional area of the third path P3 to the cross-sectional area of the second path P2 is set to 40% or more, the refrigerant blow-up effect between adjacent paths could fully be obtained and therefore the circulation of the refrigerant could be performed much more smoothly.
Therefore, between adjacent paths, when the refrigerant flowed out of the upstream side path (lower side path) goes up and flows into the downstream side path (upper side path), the liquefied refrigerant is pushed up by the blow-up effect of the rising refrigerant and introduced into the downstream side path (upper side path). As a result, a stagnation of the liquid refrigerant can be prevented, securing an enough effective area of the heat exchanging portion, which enables an enhanced cooling performance. Furthermore, since the liquefied refrigerant passes through the entire region of each path without stagnating therein, the refrigerant flow resistance can be reduced, resulting in an enhanced performance. In cases where the reduction rate of the cross-sectional area between the predetermined adjacent paths is specified, the aforementioned effects can be obtained assuredly.
This application claims priority to Japanese Patent Application No. 2000-183966 filed on June 20, 2000.
The terms and descriptions in this specification are used only for explanatory purposes and the present invention is not limited to these terms and descriptions. It should be appreciated that there are many modifications and substitutions without departing from the scope of the present invention which is defined by the appended claims. The present invention permits any design-change if it is within the limits by which the claim was performed.

Claims

Use of a condenser, which comprises:
a pair of right and left headers (11,11);

a plurality of heat exchanging tubes (12) disposed at predetermined intervals between said headers with opposite ends thereof connected with said headers;

at least one partition (16) provided in a respective one of said headers (11) to group said plurality of heat exchanging tubes (12) into a plurality of paths (P1, P2, P3); and

a refrigerant inlet (11a) provided at an end portion of one of said headers (11), and a refrigerant outlet (11b) provided at an opposite end portion of one of said headers (11),

wherein said plurality of paths includes three or more paths including a first path (P1), a second path (P2) and a third path (P3) through which said refrigerant introduced from said refrigerant inlet (11a) passes in sequence, wherein a cross-sectional area of each of said paths (P1, P2, P3) decreases stepwise towards a downstream side of said paths (P1, P2, P3) for each path, wherein a reduction rate of a cross-sectional area of said second path (P2) to a cross-sectional area of said first path (P1) is 50% or more, and wherein a reduction rate of a cross-sectional area of said third path (P3) to a cross-sectional area of said second path (P2) is 40% or more,

in a manner that

the condenser is provided with its headers (11,11) extending vertically and with the heat exchanging tubes (12) extending horizontally, wherein said refrigerant inlet (11a) is provided at a lower position, and said refrigerant outlet (11b) is provided at an upper position so that a refrigerant introduced from said refrigerant inlet (11a) passes upwardly through said plurality of paths (P1, P2, P3) in sequence in a meandering manner, and flows out of said refrigerant outlet (11b).
Use of the condenser as recited in claim 1, wherein each of said reduction rates is attained by decreasing the number of said heat exchanging tubes (12) constituting each of said paths (P1, P2, P3).
A refrigeration system having a condenser which itself comprises a pair of right and left headers (11,11); a plurality of heat exchanging tubes (12) at predetermined intervals between said headers with opposite ends thereof connected with said headers, at least one partition (16) provided in a respective one of said headers (11) to group said plurality of heat exchanging tubes (12) into a plurality of paths (P1, P2, P3); a refrigerant inlet (11a) provided at an end portion of one of said headers (11); and a refrigerant outlet (11b) provided at an opposite end portion of one of said headers (11), wherein said plurality of paths includes three or more paths including a first path (P1), a second path (P2) and a third path (P3) through which said refrigerant introduced from said refrigerant inlet (11a) passes in sequence, wherein a cross-sectional area of each of said paths (P1, P2, P3) decreases stepwise towards a downstream side of said paths (P1, P2, P3) for each path, wherein a reduction rate of a cross-sectional area of said second path (P2) to a cross-sectional area of said first path (P1) is 50% or more, wherein a reduction rate of a cross-sectional area of said third path (P3) to a cross-sectional area of said second path (P2) is 40% or more, and
wherein the condenser is arranged such that its headers (11,11) extend vertically with the heat exchanging tubes (12) extending horizontally, wherein the refrigerant inlet (11a) is provided at a lower position, and said refrigerant outlet (11b) is provided at an upper position, so that a refrigerant introduced from said refrigerant inlet (11a) passes upwardly through said plurality of paths (P1, P2, P3) in sequence in a meandering manner, and flows out of said refrigerant outlet (11b).
The refrigerator system as recited in claim 3, wherein each of said reduction rates is attained by decreasing the number of said heat exchanging tubes (12) constituting each of said paths (P1, P2, P3).