WO2005073655A1

WO2005073655A1 - Heat exchanger and air-conditioning system employing same

Info

Publication number: WO2005073655A1
Application number: PCT/JP2005/001243
Authority: WO
Inventors: Shiro Ikuta; Syouzou Hataya; Nobuhide Kasagi; Yuji Suzuki; Naoki Shikazono; Daisuke Ookawa
Original assignee: Calsonic Kansei Corporation; The University Of Tokyo; Iwamoto Co., Ltd.
Priority date: 2004-01-29
Filing date: 2005-01-28
Publication date: 2005-08-11
Also published as: JPWO2005073655A1

Abstract

Disclosed is a heat exchanger comprising first and second tubes (2) respectively having a refrigerant channel for flowing a refrigerant. The heat exchanger further comprises tanks (3, 4) respectively attached to either ends of the first and second tubes (2) for distributing the refrigerant to the first and second tubes (2). The first and second tubes (2) respectively have an outer surface which serves as a heat transfer surface and exchanges heat with the refrigerant. The pitch (P) between the first and second tubes (2) is two to four times as wide as the thickness of the first and second tubes (2).

Description

Specification

Heat exchanger and air conditioner including the same

Technical field

The present invention relates to, for example, an evaporator / condenser heat exchanger and an air conditioner including the same. More specifically, the present invention relates to a technology for further improving the heat exchange efficiency, reducing the size, and reducing the weight.

Background art

[0002] For example, a heat exchanger used in a vehicle air conditioner includes a plurality of tubes for circulating a refrigerant, a tank for distributing the refrigerant to each of the tubes, and a cooling fin provided between the tubes. (See, for example, JP-A-2001-167782).

[0003] The heat exchanger having this configuration includes cooling fins that are in contact with each tube in order to increase the area of the heat transfer surface in order to supplement the heat transfer performance on the air side with a small heat transfer coefficient.

[0004] The tube defines a plurality of refrigerant flow paths through which the refrigerant flows in order to improve the heat transfer performance on the refrigerant side and to have mechanical strength capable of withstanding high refrigerant pressure in the tube. This tube is manufactured, for example, by extrusion or by brazing these three plates with an inner fin sandwiched between two plates.

[0005] By the way, since this type of heat exchanger has a small heat transfer coefficient and a large thermal resistance on the air side, the fin pitch is reduced, or the cooling fins are provided with fine cut-and-raised slits. Improve thermal performance. However, as the air side heat transfer coefficient is improved, the heat transfer performance is reduced due to the heat conduction in the cooling fins, the so-called fin efficiency.

[0006] The fine cut and raised slits on the surface of the cooling fins cause flow separation at the ends. This delamination increases ventilation resistance beyond improving heat transfer. Furthermore, the cut-and-raised portions and slits have the problem that the durability of the cooling fins is liable to be reduced due to clogging due to dust, dew condensation, or frost formation, or the retained condensate being splashed or corroded from the ends. generate. Insufficient brazing at the junction between the tube and the cooling fins also increases the contact thermal resistance. For these reasons, it is difficult for conventional heat exchangers to achieve higher performance, smaller size, and lighter weight. Disclosure of the invention

[0007] An object of the present invention is to provide a heat exchanger that achieves higher performance, smaller size, and lighter weight of the heat exchange efficiency of the heat exchanger, and an air conditioner including the same.

[0008] A feature of the invention provides the following heat exchanger. The heat exchanger includes first and second tubes having a refrigerant passage through which the refrigerant flows. The heat exchanger includes tanks attached to both ends of the first and second tubes, respectively, for distributing the refrigerant to the first and second tubes. The first and second tubes have outer surfaces that act as heat transfer surfaces and exchange heat with the refrigerant. The pitch between the first and second tubes is two to four times the thickness of each of the first and second tubes.

[0009] Each thickness of the first and second tubes may be 1 mm or less.

[0010] At least one of the first and second tubes may have an outer peripheral surface having an uneven portion.

[0011] The convex portion of the concave-convex portion may have a coolant channel.

[0012] The concave portion of the concave-convex portion may have a coolant channel.

[0013] The refrigerant flow path may be similar in cross section to the convex portion.

The pitch of the uneven portions may be three times or less the thickness of each of the first and second tubes.

[0014] A ratio of a length of the concave portion of the uneven portion to a length of the convex portion of the uneven portion may be W2 / W1≤2.

[0015] The heat exchanger may be applied to an air conditioner.

According to the heat exchanger of the present invention, the heat transfer surface that exchanges heat with the refrigerant without using the cooling fins is formed by the outer surface of the tube. This eliminates the problems of heat exchangers using cooling fins, such as fin efficiency, increased contact heat resistance, increased ventilation resistance, clogging due to dust, dew, and frost, and fin corrosion. . In addition, by optimizing the pitch between tubes, the heat transfer coefficient on the air side is further improved, and extremely high heat exchange efficiency is exhibited. Therefore, the heat exchanger of the present invention achieves higher performance, smaller size, and lighter weight because no cooling fin is used.

[0017] Since the thickness of each tube is set to lmm or less, the thickness of the tube becomes larger than when the thickness exceeds 1mm. The number of buses increases. Due to this increase, the total cross-sectional area of the refrigerant flow path formed in this tube is sufficiently ensured, and the flow path resistance of the refrigerant is greatly reduced.

[0018] Since the tube has an uneven portion on the outer peripheral surface, the concave portion enlarges the flow path, reduces the wind speed, and reduces the ventilation resistance. Further, in the heat exchanger of the invention, since the uneven portion slightly reduces the heat transfer on the air side, the ratio of the heat transfer coefficient on the air side to the pressure coefficient is larger in a tube having unevenness than in a tube having no unevenness. This enables the heat exchanger to have higher performance, smaller size and lighter weight. When the heat exchanger of the invention is used as an evaporator, the condensed water is drawn into the recess and easily drained. This suppresses an increase in ventilation resistance, and does not cause a problem that water droplets scatter due to an increase in wind speed. Further, since this heat exchanger has a tube having an uneven outer surface, the mechanical strength is also greatly improved.

[0019] In the heat exchanger, since the refrigerant flow path is formed in accordance with the concave and convex portions formed on the outer peripheral surface of the tube, the cross section of the refrigerant flow path is made sufficiently large. As a result, the total cross-sectional area of the refrigerant flow path is secured to such an extent that an increase in pressure loss in the pipe can be saved.

[0020] If the tube has an outer peripheral surface having an uneven portion with a pitch (Wl + W2) that is three times or more the thickness (T), the flow separated from the upstream convex portion adheres to the downstream convex portion again. Weakens the effect of As a result, the rate of improvement in the heat transfer performance at the point of reattachment of the downstream convex portion where the heat transfer coefficient is improved is reduced. Pitches less than three times eliminate those problems.

[0021] Since the length of the concave portion and the length of the convex portion are not more than twice, the cross-sectional area inside the pipe is sufficiently ensured, and the pressure loss on the refrigerant side is suppressed.

[0022] A high-performance, small-sized and lightweight heat exchanger is used as an air conditioner for vehicles such as an evaporator, a radiator, an oil cooler, and a heater core. This will reduce the weight and energy consumption of the vehicle and increase the passenger's living space.

Brief Description of Drawings

FIG. 1 is a perspective view showing a heat exchanger according to a first embodiment.

FIG. 2 is a sectional view taken along the line II-II in FIG. 1.

FIG. 3 is an enlarged sectional view of a main part of the tube shown in FIG. 2.

[Fig. 4] Fig. 4 shows the heat release and power (PT) obtained by dividing the tube spacing by the tube thickness (PT). FIG. 4 is a characteristic diagram showing a change in the ratio with respect to (fan power).

FIG. 5 is a perspective view showing a heat exchanger according to a second embodiment.

FIG. 6 is a sectional view taken along the line VI-VI in FIG. 5.

FIG. 7 is an enlarged sectional view of a main part of the tube shown in FIG. 6.

FIG. 8 is a characteristic diagram showing a change in a ratio between a heat release amount and power (fan power) with respect to a value (PL) obtained by dividing a distance between uneven portions formed on a tube surface by a tube thickness (PL).

FIG. 9 is a diagram showing an example in which a heat exchanger to which the invention is applied is applied to an air conditioner.

FIG. 10 is a cross-sectional view of a tube showing another example of the tube of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

[0025] First embodiment

As shown in FIG. 1, heat exchanger 1 of the embodiment includes a plurality of tubes 2 and a pair of tanks 3 and 4 for distributing a refrigerant to each tube 2. The tanks 3 and 4 are arranged at predetermined intervals in parallel and facing each other. Both ends of each tube 2 are inserted, brazed, and integrally joined to the tanks 3 and 4 at a predetermined pitch interval. The heat exchanger 1 has no cooling fins between the tubes 2, but has an air-side heat transfer surface that exchanges heat with the refrigerant on the outer surface of the tubes 2. That is, the heat exchanger 1 forms the air-side heat transfer surface on the outer surface of the tube 2.

As shown in FIG. 2, the tube 2 functions as a long heat transfer tube having a flat cross section. The tube 2 has a plurality of refrigerant flow paths 5 through which the refrigerant flows. In order to improve the heat transfer performance on the refrigerant side and to have mechanical strength capable of withstanding the high refrigerant pressure in the tube, each refrigerant flow path 5 has holes penetrating at the upper and lower ends in the longitudinal direction of the tube 2. The plurality of refrigerant channels 5 are positioned at predetermined pitch intervals in the lateral direction of the tube 2.

[0027] The tank 3 functions as a supply tank that supplies a refrigerant. The tank 4 functions as a collection tank that collects the refrigerant that has passed through the tubes 2 and has undergone heat exchange. The tanks 3 and 4 are closed at both ends in the longitudinal direction and formed as cylindrical bodies. Tanks 3 and 4 are The tube 2 has a tube insertion hole (not shown) for inserting the end of the tube 2 into the tank. The tank 3 is attached to a refrigerant introduction pipe (not shown) for supplying the refrigerant into the tank 3. The tank 4 is attached to a refrigerant discharge pipe (not shown) for collecting the refrigerant flowing through each tube 2.

In particular, in the heat exchanger 1, the heat transfer surface that exchanges heat with the refrigerant without using cooling fins is constituted by the outer surface 2 a of the tube 2. This outer surface 2a exchanges heat with the air flows Fl, F2.

[0029] This structure has problems with a heat exchanger using cooling fins, such as increased fin efficiency, contact heat resistance, increased ventilation resistance, clogging due to dust, dew, and frost, and fin corrosion. To eliminate.

[0030] In the heat exchanger 1, in addition to the heat transfer surface being constituted by the outer surface 2a of the tube 2, as shown in Fig. 3, a pitch interval (hereinafter simply referred to as a pitch P) for disposing each tube 2 is provided. The thickness is set to 2 to 4 times the thickness T of the tube 2. When the pitch P at which the tubes 2 are arranged is set to be 2 to 4 times the thickness T of the tubes 2, the air-side heat transfer coefficient is further improved, and extremely high heat exchange efficiency is exhibited.

[0031] FIG. 4 is a characteristic showing a change in a ratio of heat release amount to power (fan power) (heat release amount / power) with respect to a value (PT) obtained by dividing a tube interval (pitch P) by a thickness T of the tube 2 (PT). FIG. The vertical axis shows the ratio of heat release to power, and the larger the number, the better the heat exchange rate. The horizontal axis shows PT. As can be seen from this characteristic diagram, setting PT between 2 and 4 greatly increases the heat exchange efficiency.

[0032] In the heat exchanger 1, the thickness T of the tube 2 is set to lmm or less. Tubes 2 having a thickness T of 1 mm or less have more tubes 2 than those having a thickness of more than 1 mm. As a result, the total cross-sectional area of the refrigerant flow path 5 formed in the tube 2 can be sufficiently ensured, and the flow resistance of the refrigerant is greatly reduced.

[0033] Therefore, the heat exchanger 1 of the present embodiment does not use cooling fins, so that higher performance, smaller size, and lighter weight can be realized.

[0034] Second embodiment

As shown in FIG. 5, the heat exchanger 10 of this embodiment basically has a plurality of tubes 20 and a refrigerant distributed to each tube 20, similarly to the heat exchanger 1 of the first embodiment. one It consists of a pair of tanks 30, 40. The air-side heat transfer surface that exchanges heat with the refrigerant is constituted by the outer surface 20a of the tube 20 (see FIG. 6).

The heat exchanger 10 has the same configuration as the heat exchanger 1 of the first embodiment, except for a tube 20 having a different shape, and a description of the same components will be omitted. . In this heat exchanger 10, the pitch P at which the tubes are arranged is set to be two to four times the thickness of the tubes, similarly to the heat exchanger 1 of the first embodiment.

As shown in FIG. 6, each tube 20 of the heat exchanger 10 has undulations 60a and 60b formed on its outer peripheral surface 20a. That is, the outer peripheral surface 20a of the tube 20 has a raised portion 60a and a recessed portion 60b formed on the front surface and the rear surface, respectively, and the concave portion 60b is formed between the adjacent refrigerant passages 50. Formed. As a result, the tube 20 becomes corrugated, and the irregular shape of the outer peripheral surface 20a matches each refrigerant flow path 50. The coolant channels 50 are respectively positioned inside the convex portions 60a. The coolant channel 50 is similar in cross section to the convex portion 60a.

In this embodiment, the uneven portions 60a and 60b have a pitch (W1 + W2) that is three times or less the thickness T of the tube 20. The thickness T of the tube 20 is defined as the maximum thickness of the tube. The pitch (Wl + W2) of the uneven portions 60a and 60b, which is three times or less the thickness T of the tube 20, increases the heat exchange efficiency. On the other hand, the pitch W of the uneven portions 60a and 60b more than three times the thickness T weakens the effect of the flow separated from the upstream convex portion to re-attach to the downstream convex portion, and improves the heat transfer coefficient. Reduce the rate of improvement in heat transfer performance at the point of side protrusion reattachment

[0038] Fig. 8 shows the ratio of the amount of heat radiation to the power (fan power) to the value (PL) obtained by dividing the pitch W of the uneven portions 60a and 60b formed on the surface of the tube 20 by the thickness T of the tube 20 (heat radiation). FIG. 6 is a characteristic diagram showing a change in (/ power). The vertical axis is the ratio of heat release to power, the larger the number, the better the horizontal axis is PL. As can be seen from this characteristic diagram, a PL of 3 or less increases the heat exchange efficiency.

[0039] According to the heat exchanger 10 configured as described above, the concave and convex portions 60a and 60b formed on the outer peripheral surface 20a of the tube 20 expand the flow path by the concave portion 60b, reduce the wind speed, and reduce the ventilation resistance. . In the heat exchanger 10, the unevenness 60a, 60b slightly reduces the heat transfer on the air side. The ratio of the air-side heat transfer coefficient to the pressure coefficient is larger for a tube with irregularities than for a tube without irregularities. As a result, the performance, size, and weight of the heat exchanger 10 can be improved.

[0040] In particular, if the heat exchanger 10 is used as an evaporator, condensed water is drawn into the recess 60b and easily drained. As a result, an increase in ventilation resistance can be suppressed, and the problem of water droplets scattering when the wind speed is increased is eliminated. Furthermore, in the heat exchanger 10, the mechanical strength of the tube 20 is greatly increased by making the outer shape of the tube 20 uneven.

[0041] In the heat exchanger 10, the refrigerant flow path 50 was formed in accordance with the concave and convex portions 60a and 60b formed on the outer peripheral surface 20a of the tube 20. That is, the positions of the refrigerant passage 50 and the protrusion 60a coincide with each other, and are similar in cross section. Thereby, the cross section of the refrigerant flow path 50 can be made sufficiently large, and the total cross-sectional area of the refrigerant flow path 50 is set to such an extent that the heat exchange performance is enhanced.

Further, in the heat exchanger 10 of the embodiment, since the ratio of the length W1 of the convex portion 60a to the length W2 of the concave portion 60b is set to W2ZW1 ≦ 2, a sufficient cross-sectional area inside the tube is ensured. In addition, the refrigerant side pressure loss is suppressed.

FIG. 9 shows an example in which the heat exchangers 1 and 10 to which the present invention is applied are applied to an air conditioner. Here, the heat exchangers 1 and 10 of the present embodiment were applied to the radiator 71, the evaporator 72, the heater core 73, and the like. In addition, the heat exchangers 1 and 10 of the present invention may be applied to an oil cooler. The heat exchanger of the present invention is not limited to a vehicle air conditioner, and may be applied to a home, business or portable air conditioner to achieve a significant compactness.

As described above, a high-performance, small-sized, and lightweight heat exchanger may be used as an air conditioner used for a vehicle such as an evaporator, a radiator, an oil cooler, and a heater core. This achieves weight reduction and energy saving of the vehicle and expansion of the passenger's living space.

As described above, specific embodiments to which the present invention is applied have been described. However, the present invention may be variously modified without being limited to the above-described embodiments.

For example, in the above-described embodiment, the coolant channel 50 is formed in accordance with the concave and convex portions 60a and 60b formed on the outer peripheral surface 20a of the tube 20. On the other hand, the air-side heat transfer performance is basically irrelevant to the coolant channel 50, and therefore, as shown in FIG. 10, the coolant channel 50 does not have to be formed in accordance with the uneven portions 60a and 60b. That is, the refrigerant passage 50 having a circular cross section is positioned in both the convex portion 60a and the concave portion 60b. This structure is the same as the heat exchanger 10 of the second embodiment. The same effect is obtained.

Industrial potential

INDUSTRIAL APPLICABILITY The heat exchanger or air conditioner of the present invention is used, for example, in vehicles and homes, and is useful in achieving higher performance, smaller size, and lighter weight.

Claims

The scope of the claims

A heat exchanger (1),

First and second tubes (2) having a refrigerant flow path (5) through which a refrigerant flows, and first and second tubes (2) attached to both ends of the first and second tubes (2), respectively. 2) a tank (3, 4) for distributing the refrigerant to the

The first and second tubes (2) have outer surfaces that act as heat transfer surfaces and exchange heat with the refrigerant,

A heat exchanger, wherein a pitch (P) between the first and second tubes (2) is two to four times a thickness of each of the first and second tubes (2).

Claim 1 of the heat exchanger (1),

The heat exchanger wherein each of the first and second tubes (1) has a thickness of 1 mm or less.

Claim 1 of the heat exchanger (10),

A heat exchanger in which at least one of the first and second tubes (20) has an outer peripheral surface on which uneven portions (60a, 60b) are formed.

Claim 3 of the heat exchanger (10),

The protrusion (60a) of the uneven portion (60a, 60b) is a heat exchanger having a refrigerant flow path (50). Claim 4 wherein the heat exchanger is

A concave part (60b) of the concave-convex part (60a, 60b) is a heat exchanger having a refrigerant flow path (50). Claim 4 of the heat exchanger (10),

The refrigerant flow path (50) is a heat exchanger (10) of the heat exchange claim 3, which is similar in cross section to the projection (60a),

A heat exchanger wherein a pitch (W1 + W2) of the uneven portions (60a, 60b) is three times or less of each thickness (T) of the first and second tubes (20).

Claim 3 of the heat exchanger (10),

A heat exchanger, wherein the ratio of the length (W2) of the concave portion (60b) of the uneven portion to the length (W1) of the convex portion (60a) of the uneven portion is W2 / W1≤2.

An air conditioner to which the heat exchanger (1, 10) of claim 1 is applied.