EP1757869A2

EP1757869A2 - Heat exchanger for air conditioner having different circuit pattern depending on distance from fan

Info

Publication number: EP1757869A2
Application number: EP06017726A
Authority: EP
Inventors: Woo-Ho Cha
Original assignee: LS Cable Ltd
Current assignee: LS Mtron Ltd
Priority date: 2005-08-26
Filing date: 2006-08-25
Publication date: 2007-02-28
Also published as: EP1757869A3; AU2006203362A1; KR100631273B1; CN1940398A

Abstract

Disclosed is a heat exchanger for an air conditioner. The heat exchanger of the invention comprises a plurality of circuits. The circuits are formed into different patterns to have path lengths different from each other, and have a shorter path length as the circuits are closer to a fan generating an air flow. According to the heat exchanger, the areas of heat contact of the circuits are different correspondingly to the differences of the flow rate and velocity of the air depending on the distances from the fan, so that the efficiency of the air conditioner can be improved.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims all benefits of Korean Patent Application No. 10-2005-78570 filed on August 26, 2005 in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a heat exchanger for an air conditioner, and more particularly to a heat exchanger comprising a plurality of circuits having different path lengths depending on distances from a fan.

Description of the prior art

In general, an air conditioner maintains a temperature in a room to be a proper temperature irrespective of external temperatures through a refrigeration cycle or heat pump cycle, and is provided with a heat exchanger allowing the refrigerant to pass through therein to exchange the heat with the ambient air.
In recent years, as the refrigeration cycle and the heat pump cycle are implemented in a single air conditioner, it is increased the propagation of an air conditioner having a combined heating/cooling function capable of selectively performing the heating/cooling in the room.
Typically, the air conditioner consists of an indoor heat exchanger, a compressor, an outdoor heat exchanger and an expansion valve. In the cooling operation, the indoor heat exchanger serves as an evaporator and the outdoor heat exchanger serves as a condenser, so that as the refrigerant under liquid state of low temperature and pressure passes through the indoor heat exchanger, it absorbs the heat in the room and is thus evaporated, thereby implementing the cooling effect. To the contrary, in the heating operation, the indoor heat exchanger serves as the condenser and the outdoor heat exchanger serves as the evaporator, so that as the refrigerant under gas state of high temperature and pressure discharged from the compressor passes through the indoor heat exchanger, it radiates the heat into the room, thereby implementing the heating effect.
In the mean time, the heat exchanger is typically comprised of plural circuits through which the refrigerant passes. Each of the circuits consists of straight tubes and bended connection tubes connecting the straight tubes. An end of the respective circuits is connected to a header and the other end is connected to a distributor, so that the refrigerant is circulated in the circuits to carry out the heat exchange.
Fig. 1 is a perspective view showing a prior heat exchanger. As shown in Fig. 1, the heat exchanger 100 has an arrangement in which plural tubes 110 are arranged in a line with two rows. The tubes 110 are connected via connection tubes 115. In the mean time, the arrangement of the tubes 110 is divided into plural circuits 120a - 120f. The refrigerant is circulated in the circuits 120a~120f through the tubes 110 constituting both ends of the respective circuits 120a~120f. In such heat exchanger, the tubes 110 of the respective circuits 120a~120f are arranged in same number and pattern. In other words, in the prior heat exchanger, the path lengths of the respective circuits 120a~120f are same, so that areas of heat contact between the respective circuits 120a~120f and the ambient air are also same.
However, in the air conditioner, the distributions of the air volume and the wind speed at the respective parts of the heat exchanger are different depending on the positions of the fan. Accordingly, if the respective circuits are formed into the same pattern (same path lengths) without considering the differences of the air volume and the wind speed depending on the positions of the fan, as the prior heat exchanger, an efficiency of the heat exchange is decreased.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made to solve the above problems. An object of the invention is to provide a heat exchanger capable of increasing an efficiency of the heat exchange by making tube patterns of plural circuits constituting a heat exchanger different, correspondingly to the difference of the air volume and the wind speed depending on distances from the fan.
In order to achieve the above object, there is provided a heat exchanger for an air conditioner having plural circuits through which refrigerant passes, wherein the circuits are formed into different patterns to have path lengths different from each other and have a shorter path length as the circuits are closer to a fan generating an air flow.
In one embodiment of the invention, each of the circuits may consist of plural straight tubes and bended return bands connecting the straight tubes. In this case, the circuits have smaller number of the straight tubes as they are closer to the fan.
In one embodiment, the circuits of the heat exchanger may form 2 to 4 circuit groups depending on the patterns thereof. Each of the circuit groups may consist of circuits of one or two patterns.
In one embodiment of the invention, the circuits of the heat exchanger may be formed with two circuit groups and a ratio of the number of the tubes in the two circuit groups may be 7:10 to 9:10.
In addition, in one embodiment of the invention, the circuits may be vertically arranged, the fan may be placed at an upper part of the heat exchanger so that the air passing through the heat exchanger flows upwardly, and the number of the tubes arranged at the upper part of the heat exchanger is smaller than that of the circuits arranged in a lower part of the heat exchanger.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view showing a heat exchanger according to the prior art;
FIG. 2 is a view schematically showing an air conditioner provided with a heat exchanger according to an embodiment of the invention;
FIGs. 3A to 3C are perspective views showing circuits of a heat exchanger according to an embodiment of the invention; and
FIG. 4 is a graph comparing temperature distributions in heat exchangers according to the prior art and an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.
Fig. 2 is a view schematically showing an air conditioner provided with a heat exchanger according to an embodiment of the invention. Figs. 3A to 3C are perspective views showing circuits of a heat exchanger according to an embodiment of the invention.
The air conditioner shown in Fig. 2 is an air conditioner having a combined heating/cooling function capable of selectively performing the heating/cooling in a room. Hereinafter, it is described a structure of the air conditioner, based on the cooling operation.
As shown in Fig. 2, the air conditioner comprises an outdoor unit 10 and an indoor unit 20. The indoor unit 20 comprises an indoor heat exchanger 21 for a heat exchange between the refrigerant and the indoor air, a compressor 40 for compressing the refrigerant, and an expansion valve 70 for expanding the refrigerant so as to decrease pressure and temperature thereof. The outdoor unit 10 comprises a plurality of outdoor heat exchangers 11 for a heat exchange between the refrigerant and the outdoor air, headers 60, 60 for supplying the refrigerant to the outdoor heat exchangers 11, a distributor 30 for recovering the refrigerant flowing from the outdoor heat exchangers 11 to circulate it into the indoor unit 20 and a fan 80 for assisting the heat exchange in the outdoor heat exchangers 11. In addition, in order to implement the cooling or heating operation, the indoor unit 20 is provided with a 4-way valve 30 for selectively changing the refrigerant flowing direction from an inlet and an outlet of the compressor 40 to the outdoor heat exchangers 11 and the indoor heat exchanger 21. In the mean time, although not shown in the drawings, a separate fan may be also provided to the indoor unit 10 for the heat exchange in the indoor heat exchanger 21 .
Each of the outdoor heat exchangers 11 is provided with plural circuits 50 which are vertically arranged in a line. Each of the circuits 50 consists of plural straight tubes and bended return bands for connecting the straight tubes, thereby forming a single refrigerant passage. In the cooling operation, the refrigerant is distributed from the header 60 and introduced into the respective circuits 50. The refrigerant having passed through the respective circuits 50 is collected through the distributor 40 and flows toward the expansion valve 70.
In the outdoor unit 10 of the embodiment, the pair of the outdoor heat exchangers 11 is symmetrically arranged at the right and left sides about any vertical axis. The fan 80 is placed at an upper part of the outdoor unit 10 between the outdoor heat exchangers 11 to discharge the circulating air in the outdoor unit 10 to the exterior. However, the arrangements of the fan 80 and the outdoor heat exchangers 11 are not limited to the embodiment and can be modified into a variety of types.
In the air conditioner described above, during the cooling operation, the indoor heat exchanger 21 serves as an evaporator and the outdoor heat exchanger 11 serves as a condenser. The refrigerant, which is compressed to high temperature and pressure by the compressor 40, is delivered to the outdoor heat exchanger 11 through a conduit 5 under gas state. The gas refrigerant under high temperature and pressure is cooled and condensed by the heat exchange with the outdoor air in the outdoor heat exchanger 11, so that it becomes liquid under low temperature and high pressure. After that, the liquid refrigerant is decompressed to be the liquid under low temperature and pressure while passing through the expansion valve 70 and is delivered to the indoor heat exchanger 21. The refrigerant delivered to the indoor heat exchanger 21 is evaporated through the heat exchange with the indoor air to cool the room, converted into the gas refrigerant under medium temperature and low pressure and then flows in the compressor 40.
In the mean time, during the heating operation, the outdoor heat exchanger 11 serves as an evaporator, the indoor heat exchanger 12 serves as a condenser and the flow of the refrigerant is opposite to that of the cooling operation.
As shown in Fig. 2, in this embodiment, each of the outdoor heat exchangers 11 is provided with fourteen circuits 50. The structures of the two upper circuits and the 12 lower circuits 52, 53 are designed to be different from each other, thereby forming a circuit group.
The fan 80 of the embodiment is placed at the upper part of the outdoor unit 10 above the outdoor heat exchangers 11, thereby blowing the circulating air in the outdoor unit 10 to the exterior. The amount and velocity of the flowing air are increased, as it is closer to the fan 80 in the outdoor unit 10. In other words, the amounts and velocity of the air flowing at the lower and upper parts of the outdoor heat exchangers 11 are different depending on the distances from the fan 80.
Considering the differences of the amounts and velocity of the air depending on the distances from the fan 80, the two circuits 51 having a pattern of a small area of heat contact due to the short flow path length of the refrigerant are placed at the upper part of the outdoor heat exchangers 11, and the circuits 52, 53 having a pattern of a large area of heat contact due to the relatively long flow path length of the refrigerant are placed at the lower part thereof.
The two upper circuits 51 has a structure as shown in Fig. 3A and the twelve lower circuits 52, 53 have structures as shown in Figs. 3B and 3C. In other words, the twelve lower circuits form a circuit group in which the two circuits 52, 53 thereof are repeated with a pair (i.e., total 6 pairs). Such arrangement of the circuits 50 is an example for patterning the circuits 50 and thus facilitating the mass production and the invention is not limited thereto.
The shapes of the circuits 51, 52, 53 shown in Fig. 2 are sectional shapes taken along a line d-d' in Figs. 3A to 3C. As shown in Fig. 2, the two upper circuits 51 consist of eight straight tubes. The lower circuits 52, 53 consist of 10 straight tubes and the circuit 52 and the circuit 53 form a pattern symmetrical to each other. Since the straight tubes constituting the respective circuits 51, 52, 53 have a same length, a whole path length of the upper circuit 51 is smaller than that of the lower circuits 52, 53. Accordingly, the area of heat contact at the circuit 51 is smaller than that of the circuits 52, 53.
In the invention, the circuits 50 of the outdoor heat exchanger 11 can be divided into 2 to 4 circuit groups depending on the patterns. In the above embodiment, it can be divided into two circuit groups, i.e., a first circuit group comprising the two circuits 51 arranged at the upper part of the outdoor heat exchangers 11 close to the fan 80 and a second circuit group comprising the two types of circuits 52, 53 arranged at the lower part of the outdoor heat exchangers 11. The respective circuit groups are arranged into a pattern of one circuit 51 and a pattern of the two circuits 52, 53. In addition, a ratio of the number of the straight tubes in the two circuit groups may be 7:10 to 9:10. As described above, in the embodiment, the ratio of the number of the straight tubes in the first and second circuit groups is 8:10.
Theoretically, the entire area of heat contact of the heat exchangers 11, 21 should be large so as to efficiently exchange the heat. However, since the path length of the circuit 50 of the heat exchangers 11, 21 should be large so as to increase the area of heat contact, the sizes of the heat exchangers 11, 21 become large. As a result, the air flow space in the indoor unit 20 or outdoor unit 10 is decreased. Accordingly, it is not desirable, regarding the general efficiency improvement of the air conditioner.
As in the embodiment, in case that the fan 80 is placed at the upper part of the outdoor unit 10 and thus the flow rate and velocity of the air are larger at the upper part of the outdoor heat exchangers 11, it is obtained the sufficient ability of the heat exchange even when the circuit 51 is used whose area of heat contact is narrow because the number of straight tubes having the short path length is small. In other words, since the amount of the flowing air adjacent to the fan 80 is large, even when the circuit 51 having the pattern in which the area of heat contact is narrow is used, it is possible to obtain the ability of heat exchange equivalent to the circuits 52, 53 having the large area of heat contact.
Fig. 4 is a graph comparing temperature distributions in the outdoor heat exchanger 11 of the invention and the prior heat exchanger. As can be seen from Fig. 4, when it is used the outdoor heat exchanger having the circuit patterns (different patterns) according to the invention, it is possible to lower the temperature distribution at the respective parts of the heat exchanger by 1 °C, as compared to the prior heat exchanger having an equal circuit pattern (i.e., pattern consisting of the same number of tubes per a circuit). Like this, when the temperature of the heat exchanger is lowered, the condensing temperature is dropped during the cooling operation, so that the overall efficiency of the air conditioner is increased.
In the above embodiment, although the descriptions are provided on the basis of the outdoor heat exchanger 11, the invention can be applied to the indoor heat exchanger 21.
As described above, according to the invention, the path lengths of the circuits constituting the heat exchanger are made to be different depending on the distances from the fan. Accordingly, it is possible to improve the efficiency of the heat exchange of the heat exchanger and the overall efficiency of the air conditioner.
While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made thereto without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

A heat exchanger(11) for an air conditioner having plural circuits(51, 52, 53) through which refrigerant passes, wherein the circuits(51, 52, 53) are formed into different patterns to have path lengths different from each other and have a shorter path length as the circuits(51, 52, 53) are closer to a fan(80) generating an air flow.
The heat exchanger(11) according to claim 1, wherein each of the circuits(51, 52, 53) consists of plural straight tubes and bended return bands connecting the straight tubes, and the circuits(51, 52, 53) have smaller number of the straight tubes as they are closer to the fan.
The heat exchanger(11) according to claim 2, wherein the circuits(51, 52, 53) of the heat exchanger(11) form 2 to 4 circuit groups depending on the patterns thereof.
The heat exchanger(11) according to claim 3, wherein each of the circuit groups consists of circuits(51, 52, 53) of one or two patterns.
The heat exchanger(11) according to claim 3, wherein the circuits(51, 52, 53) of the heat exchanger(11) form two circuit groups and a ratio of the number of the tubes in the two circuit groups is 7:10 to 9:10.
The heat exchanger(11) according to claim 2, wherein the circuits(51, 52, 53) are vertically arranged, the fan(80) is placed at an upper part of the heat exchanger(11) so that the air passing through the heat exchanger(11) flows upwardly, and the number of the tubes of the circuit(51) arranged at the upper part of the heat exchanger(11) is smaller than that of the circuits(52, 53) arranged in a lower part of the heat exchanger(11).