Patent Application
20100186936
The present invention relates to a heat exchanger such as a condenser for use in a refrigeration cycle for car air-conditioners, household air-conditioners or cooling devices for electronics devices and a heat exchanger tube to be applied to such a heat exchanger.
Conventionally, as a condenser for use in a refrigeration cycle of car air-conditioners, a heat exchanger 50 as shown in
This heat exchanger 50 includes a pair of vertically disposed headers 52 and 52, a plurality of heat exchanger tubes 53 disposed in parallel each other with the opposite ends communicated with the headers 52 and 52, fins 54 disposed between the adjacent tubes 53 and at the outside of the outermost tube 53 and side plates 55 disposed at the outside of the outermost fin 54. The heat exchanger tubes 53 are grouped into a plurality of passes C1 to C3 by partitioning members 56 provided in the headers 52 and 52. A gaseous refrigerant introduced via the refrigerant inlet 57 provided at the upper portion of one of the headers 52 passes through each of the passes C1 to C3 in turn, and is condensed by exchanging heat with the ambient air while passing through the passes. The condensed refrigerant flows out through the refrigerant outlet 58 provided at the lower portion of the other header 52.
As a tube 53 used for such a heat exchanger 50, an aluminum extruded tube of a flat shape having a thickness smaller than a width and a plurality of refrigerant flow passages 53a each having a rectangular cross-sectional shape and extending in the tube longitudinal direction is widely used.
The aforementioned heat exchanger 50 is usually installed in a vehicle such as a car or a truck. In recent years, such a vehicle is required to be small in size and light in weight for the purpose of increasing the fuel economy, decreasing the harmful emission gas (CO2, NOx), decreasing the amount of refrigerant. Accordingly, all of the automobile parts are also required to be high in performance as well as small in size and light in weight. This requirement is also applied to the heat exchanger 50 without exception.
In order to decrease the weight of the heat exchanger tube 53, it is considered to decrease the tube height or the thickness of the peripheral wall of the tube 53.
However, the passage cross-sectional area of the refrigerant flow passage 53a decreases as the tube height decreases, causing increased passage flow resistance and increased pressure loss, which in turn may sometimes cause deterioration of the condenser performance.
Further, if the thickness of the exterior peripheral wall of the tube 53 is simply formed into a thin wall, the pressure resistance deteriorates and it becomes difficult to form an enough sacrifice corrosion resistance layer, which in turn causes deterioration of corrosion resistance.
The present invention aims to solve the aforementioned prior art problems and provide a heat exchanger tube and a heat exchanger capable of improving the heat exchanging performance while decreasing the size and weight.
Another objects of the present invention will be apparent from the following explanation.
The inventors have analyzed a structure of a heat exchanger such as a condenser, especially a heat exchanger tube adapted to such a heat exchanger, from all angles in detail, and then repeatedly performed detailed experiments/studies based on the analyzed results. As a result, they have found the optimal conditions of a heat exchanger and its tube capable of attaining the aforementioned objects, and completed the present invention.
According to the first invention, a heat exchanger tube is provided with a flat tube main body with a certain length having a plurality of refrigerant flow passages each extending in a tube longitudinal direction and disposed in parallel with each other in a tube widthwise direction, wherein the following relations are established:
Ac/At×100=30 to 55; and
P/L×100=150 to 325,
wherein a total cross-sectional area of the tube main body (including the refrigerant flow passage portion) is “At”, a total cross-sectional area of the refrigerant flow passages is “Ac”, an external peripheral length of the tube main body is “L”, and a total internal peripheral length of the refrigerant flow passages is “P”.
An example of the structure of the heat exchanger tube according to the present invention will be explained in detail with reference to the drawings. As shown in
This heat exchanger tube 1 has a flat tube main body 2 having the height H smaller than the width W.
The tube main body 2 is provided with a plurality of refrigerant flow passages 5 rectangular in cross-section extending in the tube longitudinal direction and arranged in the tube widthwise direction.
Here, as mentioned above, in the heat exchanger tube 1 according to the present invention, it is necessary to set “Ac/At×100” and “P/L×100” to be “30 to 55” and “150 to 325”, respectively, as shown in
That is, in cases where Ac/At is less than 30%, the refrigerant flow resistance and the pressure loss increase, which may cause an increased tube weight. To the contrary, in cases where Ac/At exceeds 55%, the flow passage cross-sectional area increases, the flow velocity of the refrigerant in the tube decreases and the heat transfer rate deteriorates. In cases where Ac/At is not larger than 55%, even if the flow velocity in the tube is low, excellent heat performance can be obtained by keeping enough tube interior peripheral length “P”.
Furthermore, in cases where P/L is less than 150%, the heat transfer performance deteriorates, resulting in insufficient heat performance as a heat exchanger. In other words, in cases where P/L is 150% or more, if Ac/At is less than 30%, the refrigerant pressure loss increases remarkably. However, this increase of refrigerant pressure loss can be suppressed by setting Ac/At to be 30% or more.
Furthermore, if P/L is larger than 325%, in case of an aluminum extruded tube, the extrusion die becomes a minute configuration, which may cause a problem in manufacturing the tube. Even if a three-dimensional configuration processing method or a method of forming communication apertures (refrigerant flow passages) by roll forming is employed, the die becomes a minute configuration, which also may cause a problem in manufacturing the tube.
Furthermore, in the first invention, in order to obtain the aforementioned characteristics, it is preferable to employ the following structure.
That is, in the first invention, it is preferable to employ the structure in which Ac/At is set to be 45% or less and P/L is set to be 200% or more. Furthermore, it is more preferable to employ the structure in which Ac/At is set to be 35% or more and 40% or less and P/L is set to be 250% or more.
The specific range of the aforementioned numerals can be obtained from the graphs shown in
As will be apparent from these graphs, in cases where Ac/At and P/L fall within the aforementioned essential range or preferable range, the heat transfer quantity Q is large, which reveals that the tube falling within the range shown in
On the other hand, in the first invention, it is preferable to employ the structure in which the following relation is established: H=0.5 to 1.5 mm, wherein the height H of the tube main body 2 is “H”.
That is, as shown in
Furthermore, in the first invention, it is preferable to employ the structure in which the relation of W=10 to 20 mm is established, wherein the width of the aforementioned tube main body is “W”.
That is, if the width “W” of the tube main body 2 is too large, the size of the apparatus becomes large. To the contrary, if the width “W” is too small, there is a fear that it becomes difficult to keep enough heat transferring characteristic.
Furthermore, in the present invention, in the refrigerant flow passage 5 formed in the tube, the heat transfer characteristic can be increased as the interior peripheral length P increases and the passage flow resistance can be decreased as the cross-sectional increases. Accordingly, it is preferable to form the cross-sectional configuration of the refrigerant flow passage 5 not into a circular shape but into a rectangular shape (quadrangular shape) in order to increase the interior peripheral length “P” and the cross-sectional area.
As mentioned above, in the present invention, it is necessary to set the total interior peripheral length of the refrigerant flow passages to the total tube peripheral length “P/L” to be larger than a specific value as mentioned above.
In order to increase “P/L” or to set “P/L” to be 150% or more, it is considered to employ a method for increasing the number of refrigerant flow passages 5 to the unit tube width “N/W” and a method for forming protruded micro fins 5a on the interior surface of the refrigerant flow pass 5 as shown in
Furthermore, in the first invention, if the number of the refrigerant flow passages 5 to the tube width “N/W” decreases too much, the number of partition walls 4 decreases, which in turn may cause deterioration of the pressure resistance. Therefore, it is necessary to set “N/W” to be larger than ⅝.
That is, in the first invention, it is preferable to employ the structure in which the relation of ⅝<N/W is established, wherein the number of the aforementioned refrigerant flow passages is “N” and the tube width is “W”.
Furthermore, in the first invention, although the refrigerant flow passage 5 has a rectangular cross-section as mentioned above, in cases where the passage height “H−2Tb” is very small, even if the curvature radius of the portion of the tube forming die corresponding to the corner portion of the refrigerant flow passage 5 is set to be “0 (zero)”, the corner portion of the refrigerant flow passage 5 is formed into a gentle arc-shape due to the influence of the metal flow at the time of extrusion. This may sometimes cause an excessive radius “R” relative to the passage 5. Concretely, as shown in
That is, in the first invention, it is more preferable to employ the structure in which the relation of R<(H−2Tb)×⅓ is established, wherein the curvature radius of the corner portion in the cross-section of the refrigerant flow passage is “R”, the height of the aforementioned tube main body is “H” and the thickness of the external peripheral wall of the tube main body is “Tb”.
Furthermore, in the first invention, it is more preferable to employ the structure in which the relation of Tb×⅛<Ta<Tb×⅔ is established, wherein the thickness of the partition wall between the adjacent refrigerant flow passages in the tube main body is “Ta”, and the thickness of the external peripheral wall of the tube main body is “Tb”.
That is, as shown in
Furthermore, in cases where the partition wall thickness Ta is too thin, the strength of the partition wall 4 may deteriorates, which in turn may deteriorate the pressure resistance of the tube. Therefore, it is preferable that the partition wall thickness Ta is set to be larger than one eighth (⅛) of the external peripheral wall thickness Tb.
Accordingly, in the present invention, it is preferable that the relation of “Tb×⅛<Ta<Tb×⅔” is established as mentioned above.
Furthermore, in the present invention, it is more preferable to employ the structure in which the mass velocity of the refrigerant passing through the refrigerant flow passage is set to be 50 to 800 kg/m2 sec.
That is, in cases where this structure is employed, the heat transfer rate can be improved, resulting in excellent heat exchanging performance.
In the present invention, it is possible to employ the structure in which the tube main body is composed of a tube external peripheral wall member constituting the external peripheral wall and an inner plate inserted in the external peripheral wall member to form refrigerant flow passages.
For example, the heat exchanger tube 11 as shown in
Furthermore,
Furthermore, in the present invention, it is possible to employ the structure in which the tube main body includes a tube upper side member constituting the upper side of the tube main body, a tube lower side member constituting the lower side thereof and a partition plate disposed between the upper and lower side members, wherein the partitioning plate partitions each refrigerant flow passage into upper and lower portions to thereby form a multi layer structure.
For example, as shown in
Furthermore, in the present invention, it is also possible to employ a heat exchanger tube whose tube main body is made of a press formed article.
As shown
In the heat exchanger tubes according to modified embodiments shown in
On the other hand, the second invention specifies the heat exchanger such as a condenser using the heat exchanger tube of the first invention.
That is, according to the second invention, a heat exchanger includes a pair of headers disposed in parallel and a plurality of flat tubes with opposite ends thereof communicated with the headers, wherein refrigerant introduced via an refrigerant inlet of the header passes through the flat tubes while being exchanged heat and flows out of a refrigerant outlet of the header, wherein the flat tube has a flat tube main body having a predetermined length and a plurality of refrigerant flow passages each extending in the tube longitudinal direction and arranged in parallel in the tube widthwise direction, and wherein the relations of “Ac/At×100=30 to 55” and “P/L×100=150 to 325” are established, wherein the total cross-sectional area of the tube main body (including the refrigerant flow passages) is “At”; the total cross-sectional area of the refrigerant flow passages is “Ac”; the external peripheral length of the tube main body is “L” and the total peripheral length of the refrigerant flow passages is “P”.
Since the heat exchanger of the second invention specifies the heat exchanger using the heat exchanger tube of the first invention, the same functions and effects as mentioned above can be obtained.
On the other hand, the present inventors eagerly conducted detailed experiences and studies based on the aforementioned first invention and further found appropriate constitutional elements.
As a result, according to the third invention, a heat exchanger tube includes a flat tube main body having a predetermined length provided with a plurality of refrigerant flow passages of a rectangular cross-section extending in the tube longitudinal direction and arranged in parallel in the tube widthwise direction, wherein the following formulas are established:
0.5 mm<H<1.5 mm (f1)
⅝<N/W (f2)
R<(H−2Tb)×⅓ (f3)
Tb×⅛<Ta<Tb×⅔ (f4)
wherein the height of tube main body is “H”; the width of tube main body is “W”; the number of the refrigerant flow passages is “N”; the curvature radius of the corner portion in the cross-section of the refrigerant flow passage is “R”; the thickness of the external peripheral wall of the tube main body is “Tb”; and the thickness of the partition wall between the adjacent refrigerant flow passages in the tube main body is “Ta”.
These formulas (f1) to (f4) have been explained in the first invention, and the heat exchanger tube of the third invention satisfying all of these formulas (f1) to (f4) is excellent in heat exchanging performance because of the reasons mentioned above.
Furthermore, in the third invention, in order to improve the heat transfer rate, it is preferable to employ the structure in which the mass velocity of the refrigerant passing through the refrigerant flow passage is set to be 50 to 800 kg/m2 sec.
On the other hand, the fourth invention specifies the heat exchanger such as a condenser using the heat exchanger tube of the third invention.
That is, according to the fourth invention, a heat exchanger includes a pair of headers disposed in parallel and a plurality of flat tubes with opposite ends thereof communicated with the headers, wherein refrigerant introduced via an refrigerant inlet of the header passes through the flat tubes while being exchanged heat and flows out of a refrigerant outlet of the header, wherein the flat tube has a flat tube main body having a predetermined length and a plurality of refrigerant flow passages each extending in the tube longitudinal direction and arranged in parallel in the tube widthwise direction, and wherein the following formulas are established:
0.5 mm<H<1.5 mm (f1)
⅝<N/W (f2)
R<(H−2Tb)×⅓ (f3)
Tb×⅛<Ta<Tb×⅔ (f4)
wherein the height of tube main body is “H”; the width of tube main body is “W”; the number of the refrigerant flow passages is “N”; the curvature radius of the corner portion in the cross-section of the refrigerant flow passage is “R”; the thickness of the external peripheral wall of the tube main body is “Tb”; and the thickness of the partition wall between the adjacent refrigerant flow passages in the tube main body is “Ta”.
Since this fourth invention specifies the heat exchanger using the heat exchanger tubes of the third invention, the same functions and effects as mentioned above can be obtained.
Furthermore, in the fourth invention, in order to improve the heat transfer rate, it is preferable to employ the structure in which the mass velocity of the refrigerant passing through the refrigerant flow passage is set to be 50 to 800 kg/m2 sec.
Hereinafter, examples and comparative examples related to the invention will be detailed.
As shown in Table 1, a heat exchanger tube in which the total cross-sectional area of the refrigerant flow passages Ac was 6.5 mm2, the total cross-sectional area of the tube main body was 18.1 mm2, Ac/At was 35.8%, P/L was 325%, the total interior peripheral length of the refrigerant flow passages P was 104 mm, the external peripheral length of the tube main body was 32.1 mm, the number of refrigerant flow passages was 35, the tube main body height H was 1.15 mm, the tube main body width W was 16 mm, the partition wall thickness Ta was 0.06 mm, the thickness of the external peripheral wall Tb was 0.25 mm and the curvature radius R of the refrigerant flow passage was 0.05 mm, was prepared.
A multi-flow type condenser shown in
In the same manner as in the aforementioned Example, Condensers were formed by using the heat exchangers shown in Tables 1 and 2, and measurements were performed in the same manner.
As shown in Tables 1 and 2, in the heat exchanger related to the present invention, they are excellent in heat transfer and in heat performance.
In each condenser of the aforementioned Examples 1-3 and Comparative Examples 1 and 2, the relation between P/W and the heat transfer ha is shown in the graph shown in
Inner pressure was applied to each condenser of Examples 4-6 and Comparative Examples 3 and 4, and the burst pressure [MPa] was measured. In each heat exchanger tube, the aforementioned measurement was performed in the state in which zinc diffusion layer (sacrifice corrosion layer) was removed.
The measured results were shown in the graph in
This application claims priority to Japanese Patent Application No. 2000-356968 filed on Nov. 24, 2000, the disclosure of which is incorporated by reference in its entirety.
The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intent, in the use of such terms and expressions, of excluding any of the equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.
As mentioned above, according to the heat exchanger tube of the present invention and the heat exchanger using the tubes, it is possible to reduce the weight and improve the heat exchanging performance. Therefore, they are preferably used for a refrigeration system especially as a car air-conditioning refrigeration system.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2000-356968 | Nov 2000 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10432439 | Oct 2003 | US |
| Child | 12752663 | US |
