KR20080108620A - Fin-and-tube type heat exchanger, and its return bend pipe - Google Patents

Abstract

Provided is a fin-and-tube type heat exchanger using a return bend pipe capable of improving the evaporation performance of the heat exchanger still better. This heat exchanger comprises a hair pin unit having a multiplicity of hair pin pipes arranged in parallel, a return bend unit having a multiplicity of such return bend pipes arranged in parallel as are jointed to the individual hair pin pipe end portions of the hair pin portions, and a fin portion having a multiplicity of fins arranged in parallel at a constant spacing on the outer surfaces of the hair pin pipes. The pipe insides are fed with a coolant. The heat exchanger has first grooves formed in the inner faces of the return bend pipes. The groove pitch ratio (P1/P2) between a first groove pitch (P1), as taken in the section normal to the pipe axis, of the first grooves, and a second groove pitch (P2), as taken in the section normal to the pipe axis, of second grooves of a helical shape formed in the pipe inner faces of the hair pin pipes satisfies 0.65 to 2.2. At the same time, the groove sectional area ratio (S1/S2) between a first groove sectional area (S1) per groove, as taken in the section normal to the pipe axis, of the first grooves and a second groove sectional area (S2) per groove, as taken in the section normal to the pipe axis, of the second grooves satisfies 0.3 to 3.6. ® KIPO & WIPO 2009

Description

FIN-AND-TUBE TYPE HEAT EXCHANGER, AND ITS RETURN BEND PIPE}

The present invention relates to a fin-end in which, in a heat exchanger such as an air conditioner, a refrigerant such as a freon-based refrigerant or a natural refrigerant flows inside a tube, and a plurality of fins formed of aluminum or the like are installed on the outer surface of the tube in parallel. A fin-and-tube type heat exchanger and a return bend pipe connected to the hairpin pipe thereof.

Conventionally, Patent Document 1 or Patent Document 2 proposes a fin-and-tube heat exchanger using a smooth pipe having a smooth inner tube surface as a return bend tube and a pipe having an inner groove as a hairpin tube. Moreover, in patent document 1, a return bend tube is described as a U bend tube, and a hairpin tube is an electric sealing tube, In patent document 2, a return bend tube is described as a U bend and a hairpin tube are heat-transfer tubes.

In addition, Patent Document 3 also proposes a fin-and-tube heat exchanger for an evaporator using a tube having an inner groove as a return bend tube and a smooth tube as a hairpin tube. In Patent Document 3, the return bend tube is described as a U bend tube, and the hairpin tube is described as a tube. Furthermore, Patent Document 4 discloses a fin-and-tube heat exchanger using a tube having inner grooves in both a return bend tube and a hairpin tube.

On the other hand, hydrochlorofluorocarbon refrigerants such as R22 (chlorodifluoromethane), which have conventionally been used as refrigerants for fin-and-tube heat exchangers, destroy the ozone layer and thus cannot be used in view of global environmental protection. And hydrofluorocarbon refrigerants such as R410A in which all of the chlorine contained is replaced with hydrogen are being adopted in earnest as refrigerants for air conditioning equipment.

Patent Document 1: Japanese Unexamined Utility Model No. 1988-154986 (Examples, FIGS. 1 to 4)

Patent document 2: Unexamined-Japanese-Patent No. 1999-190597 (paragraph 0022-0026, FIG. 1)

Patent Document 3: Japanese Unexamined Utility Model No. 1992-122986 (paragraphs 0007 to 0008, FIG. 1)

Patent Document 4: Japanese Unexamined Patent Publication No. 2006-98033 (claim 1, Fig. 4)

(Tasks to be solved by the invention)

However, in the heat exchangers of Patent Literatures 1 and 2, the refrigerant flowing in the hairpin tube becomes a swirl flow along the groove formed in the inner surface of the tube, flows into the return bend tube, and the swirl flow is maintained for a while. However, since the inner surface of the return bend tube is smooth, it is difficult to maintain the swirl flow on the exit side, and droplets of the droplets (refrigerant liquid film) are generated at the bent portion of the return bend tube, resulting in unstable liquid film flow. . Therefore, after the hairpin tube flows into the next stage, it is consumed to reapply swirl flow to the refrigerant for a while. In this section, the flow of the refrigerant is unstable, and a thick portion of the refrigerant liquid film is formed, so that the heat transfer rate in the tube decreases. It was easy to do it, and there existed a problem that sufficient evaporation performance was not obtained.

Moreover, in the heat exchanger of patent document 3, since a groove | channel is formed in a return bend tube and a groove | channel is not formed in a hairpin tube, both in-tube shapes are largely different. Therefore, since the pressure loss of the refrigerant | coolant circulating inside becomes large and the refrigerant flow volume decreases by this, there existed a problem that the heat transfer performance, especially the evaporation performance of a heat exchanger became remarkable.

Then, as in Patent Literature 3, in consideration of the strength drop caused by the groove formation of the return bend tube, if the tube thickness is made thick, a step that causes a disturbance of the refrigerant flow occurs on the inner surface of the junction portion of the return bend tube and the hairpin tube, resulting in a refrigerant. Pressure loss tends to be large.

Moreover, in the heat exchanger of patent document 4, although the groove lead angle which the groove | channel and tube axis which the groove | channel formed in a return bend tube and a hairpin tube forms is limited to a predetermined thing, since the groove pitch and groove cross-sectional area were not examined, in a pipe | tube, Disturbance occurred in the coolant liquid film of, resulting in uneven cooling of the coolant liquid in the straight portion of the hairpin tube, resulting in a thick portion of the coolant liquid film. As a result, there was a problem that sufficient evaporation performance was not obtained.

In more detail, the non-uniformity of the refrigerant liquid film means that the liquid film thickness becomes nonuniform, and when the liquid film thickness becomes nonuniform, the state difference (a function of the surface tension of the refrigerant liquid film and the curvature of the liquid film) in the thick and thin portions of the liquid film becomes Occurs. When this state difference occurs, in principle, the liquid film with a thinner liquid film thickness is stretched toward the thicker liquid film, and as a result, the thin portion of the coolant liquid film becomes thinner, so that evaporation is promoted in this portion, while the thick portion of the coolant liquid film remains. do. As a result, remaining of the refrigerant liquid film becomes a dry out state other than the remaining portion, and the effective heat transfer area decreases, and the evaporation performance is lowered.

This invention is made | formed in view of the said problem, and an object of this invention is to provide the fin-and-tube type heat exchanger and its return bend tube which can further improve the evaporation performance of a heat exchanger.

(Means to solve the task)

According to a first aspect of the present invention, there is provided a hairpin section in which a plurality of hairpin tubes are parallel, a return bend section in which a plurality of return bend tubes joined to end portions of the hairpin tubes are parallel, and an outer surface of the hairpin tube. A fin-and-tube type heat exchanger having a fin section consisting of a plurality of fins paralleled at regular intervals and supplied with refrigerant inside the tube, the fin groove having a first groove formed on an inner surface of the tube of the return bend tube, wherein the first groove is provided. Groove pitch ratio (P1 /) of the first groove pitch (P1) in the cross section of the tube axis orthogonal to the second groove pitch (P2) in the cross section of the tube axis orthogonal cross section of the spiral second groove formed in the tube inner surface of the hairpin tube. P2) satisfies 0.65 to 2.2, and further includes a first groove cross-sectional area S1 per groove in the tubular orthogonal cross section of the first groove and one groove in the tubular orthogonal cross section of the second groove. The groove cross-sectional area ratio S1 / S2 of the second groove cross-sectional area S2 is 0.3 Pin satisfying if 3.6 is constructed as a tubular heat exchanger-and.

According to the above arrangement, the predetermined first groove is formed on the inner surface of the tube of the return bend tube of the fin-and-tube heat exchanger, whereby the refrigerant liquid film can be planarized at the inlet side of the return bend tube. "Circular flow" can be formed in the refrigerant liquid film inside the pipe, and the disturbance of the refrigerant liquid film in the return bend pipe is reduced. Then, when liquid refrigerant flows into the hairpin tube of the next stage from the return bend tube outlet side, a uniform "annular flow" is formed by the inside of the tube, and the refrigerant liquid film in the straight pipe portion of the hairpin tube becomes uniform, Heat exchange is stabilized, the evaporation performance is improved.

It is preferable that the second groove lead angle θ2 formed between the second groove and the tube axis of the hairpin tube is 15 ° or more.

According to the above structure, when liquid refrigerant flows into the hairpin tube of the next stage from the return bend tube outlet, a uniform "annular flow" is formed by the inside of the tube, and the refrigerant liquid film becomes uniform in the straight pipe portion of the hairpin tube, Heat exchange with the outside is stabilized, and the evaporation performance is further improved.

In addition, it is preferable that at least a portion of the refrigerant passage consisting of the hairpin tube and the return bend tube branch to form a plurality of refrigerant passages.

According to the above configuration, the refrigerant flow path of the fin-and-tube heat exchanger is branched, so that the refrigerant mass velocity per branch is lowered, and in particular, the refrigerant velocity at the inlet side of the return bend tube is lowered, thereby reducing the refrigerant liquid film formed inside the tube. "Circular flow" is stabilized more. Then, when liquid refrigerant flows into the hairpin tube of the next stage from the return bend tube outlet side, a uniform "annular flow" is formed by the inside of the tube, and the refrigerant liquid film becomes uniform in the straight pipe portion of the hairpin tube, Heat exchange is stabilized, and the evaporation performance is further improved.

In addition, it is preferable that the said refrigerant is a non-azeotropic mixed refrigerant of a hydrofluorocarbon system.

According to the above configuration, the evaporation performance of the heat exchanger is further improved, and the pressure loss of the refrigerant is reduced.

The second aspect of the present invention is a return bend tube used in a fin-and-tube type heat exchanger joined to a tube end of a hairpin tube having a plurality of fins parallel to the outer surface at regular intervals, and supplied with refrigerant in the tube. A second groove having a first groove formed on the inner surface of the tube of the return bend tube, the first groove pitch P1 in the cross section perpendicular to the tube axis of the first groove, and the spiral second formed on the inner surface of the tube of the hairpin tube. The groove pitch ratio P1 / P2 of the second groove pitch P2 in the tubular orthogonal cross section of the groove satisfies 0.65 to 2.2, and the first per groove in the tubular orthogonal cross section of the first groove. The groove cross-sectional area S1 and the groove cross-sectional area ratio S1 / S2 of the second groove cross-sectional area S2 per groove in the tubular orthogonal cross section of the second groove constitute a return bend tube satisfying 0.3 to 3.6. will be.

According to the above structure, by setting the groove pitch ratio P1 / P2 and the groove cross-sectional area ratio S1 / S2 within a predetermined range, the "orbital flow" of the liquid refrigerant formed in the hairpin tube is maintained even in the return bend tube. . In addition, when the liquid refrigerant flows into the return bend tube from the hairpin tube, it is possible to planarize the refrigerant liquid film at the inlet side of the return bend tube and to form a "circular flow" in which the refrigerant liquid film inside the tube is uniform. have. As a result, disturbance of the refrigerant liquid film inside the return bend tube is reduced. When the liquid refrigerant flows into the hairpin tube of the next stage from the return bend tube outlet side, a uniform "annular flow" is formed by the inside of the tube, so that the refrigerant liquid film in the straight pipe portion of the hairpin tube becomes uniform, Heat exchange with air) is stabilized, and the evaporation performance is improved.

The angle difference θ1-θ2 between the first groove lead angle θ1 formed by the first groove and the tube axis, and the second groove lead angle θ2 formed by the second groove and the tube axis is -15 ° to + 15 °. And the groove depth ratio h1 of the first groove depth h1 in the tubular orthogonal cross section of the first groove and the second groove depth h2 in the tubular orthogonal cross section of the second groove. h2) preferably satisfies 0.47 to 1.5.

According to the above configuration, by setting the angle difference θ1-θ2 of the groove lead angle to a predetermined range, when the liquid refrigerant flows into the return bend tube from the hairpin tube, the droplet of the refrigerant liquid film can be suppressed. Then, when liquid refrigerant flows into the hairpin tube of the next stage from the return bend tube outlet side, a uniform "annular flow" is formed by the inside of the tube, and the refrigerant liquid film in the straight pipe portion of the hairpin tube becomes uniform, Heat exchange is stabilized, and the evaporation performance is further improved.

In addition, by setting the groove depth ratio h1 / h2 within a predetermined range, separation of the coolant in the tube is unlikely to occur, and the coolant liquid film is less likely to be disturbed. Then, when liquid refrigerant flows into the hairpin tube of the next stage from the return bend tube outlet side, a uniform "annular flow" is formed by the inside of the tube, and the refrigerant liquid film in the straight pipe portion of the hairpin tube becomes uniform, Heat exchange is stabilized, and the evaporation performance is further improved.

Moreover, it is preferable that the chief L of the said return bend tube is 1.0-1.5 times the pitch P.

According to the above configuration, when the straight pipe portion of the hairpin tube and the return bend tube are used together, the length of the chief L of the return bend tube is set to a predetermined multiple of the bending pitch P to the return bend tube inlet to the bent portion. Is sufficiently formed in the refrigerant liquid film of the straight pipe portion of the tube. As a result, disturbances (peel-offs) do not occur in the refrigerant liquid film at the bent portion of the return bend tube. Then, when the liquid refrigerant flows into the hairpin tube of the next stage, it is introduced with the "circular flow" formed, and the refrigerant liquid film in the straight pipe portion of the hairpin tube becomes uniform, so that heat exchange with the outside of the tube is stabilized, and the evaporation performance is further increased. Is improved.

In addition, the material of the return bend tube is preferably made of a material having a lower thermal conductivity than the material of the hairpin tube.

According to the above arrangement, the heat conductivity of the tube body portion (return bend tube) is lower than that of the hairpin tube, whereby the heat loss in the return bend tube is suppressed. By suppressing the heat loss in the return bend tube, the refrigerant evaporation does not occur inside the return bend tube, or the "cyclic flow" of the refrigerant liquid film does not collapse, and the refrigerant liquid film is disturbed due to the splash of the refrigerant liquid film. (Peeling) does not occur. As a result, when liquid refrigerant flows into the hairpin tube of the next stage, it flows in with "cyclic flow" formed, and the refrigerant liquid film in the straight pipe portion of the hairpin tube becomes uniform, and the heat exchange with the outside of the tube is stabilized, and the evaporation performance is improved. Even better.

In addition, the material of the return bend tube is preferably made of a copper alloy having heat resistance than the material of the hairpin tube.

According to the above configuration, since the return bend tube is made of a heat-resistant copper alloy, when the return bend tube and the hairpin tube are joined (soldered), the decrease in the strength of the tube after the soldering of the return bend tube is reduced. The internal pressure does not cause tube breakage at the junction of the return bend tube, such as the temperature affected portion of the solder.

In addition, it is not necessary to increase the thickness of the pipe of the return bend pipe.

Further, it is preferable that the first maximum inner diameter ID1 of the return bend tube is (ID1) ≥ (ID2) in relation to the second maximum inner diameter ID2 of the hairpin tube.

According to the above configuration, when the liquid refrigerant flows into the hairpin tube from the return bend tube, the state of formation of "annular flow" is more uniformly maintained, and the refrigerant liquid film near the inlet side of the hairpin tube spreads in the circumferential direction, whereby the refrigerant liquid film Can be thinned. As a result, the evaporation performance in the straight portion of the hairpin is further improved.

(Effects of the Invention)

According to the fin-and-tube type heat exchanger of the 1st aspect of this invention, it is possible to improve the evaporation performance of a heat exchanger by using said return bend tube. Further, by using a hairpin tube, a branched refrigerant flow path, and a predetermined refrigerant having a groove lead angle in a predetermined range, it is possible to further improve the evaporation performance of the heat exchanger.

According to the return bend tube of the 2nd aspect of this invention, by making the groove pitch and groove cross-sectional area of the 1st groove of a return bend tube into a predetermined range, "annular flow" is formed in the refrigerant liquid film inside a tube, and a hairpin tube The coolant liquid film in the straight pipe portion of the film becomes uniform, which makes it possible to improve the evaporation performance of the heat exchanger. In addition, it is possible to further improve the evaporation performance of the heat exchanger by setting the groove lead angle, groove depth, sheath, thermal conductivity, and maximum internal diameter of the first groove of the return bend tube within a predetermined range. By configuring the return bend tube with a heat resistant copper alloy, the reliability of the junction portion with the hairpin tube can be increased, and the weight can be achieved.

1 is a perspective view showing the configuration of a return bend tube according to the present invention;

2 is a partial broken front view showing an example of a fin-and-tube type heat exchanger assembled with a return bend tube according to the present invention;

Figure 3 (a) is a perspective view of the heat exchanger of Figure 2 seen from the return bend tube, (b) is a perspective view of the heat exchanger from the hairpin tube side, (c) is a schematic diagram schematically showing the flow of the refrigerant in the heat exchanger,

4 is an enlarged cross-sectional view when cut in the tube axis direction showing an example of a junction of a hairpin tube and a return bend tube;

(A) is the orthogonal cross section of the tube axis of a return bend tube, (b) is a partially expanded sectional view of (a),

(A) is the orthogonal cross section of the tube of a hairpin tube, (b) is a partially expanded sectional view of (a),

(A), (b) is a schematic diagram which shows schematically the flow of a refrigerant | coolant in the heat exchanger of other embodiment which concerns on this invention,

(A) is a schematic diagram of the suction type wind tunnel used when measuring the evaporation performance of a heat exchanger, (b) is a schematic diagram of the refrigerant supply apparatus which supplies a refrigerant | coolant to the suction type wind tunnel of (a).

(Explanation of the sign)

1: Return Bend Pipe 1a: Pipe Body

2: first groove 3: first pin

11: hairpin tube 12: second groove

13: second fin 20, 20A, 20B: heat exchanger

21: pin 21a: pin

22: return bend part 23: hairpin part

P1: first groove pitch P2: second groove pitch

S1: first groove cross section S2: second groove cross section

θ1: first groove lead angle θ2: second groove lead angle

h1: first groove depth h2: second groove depth

L: Chieftain P: Pitch

ID1: 1st maximum inner diameter ID2: 2nd maximum inner diameter

OD1: Outer diameter of the first tube OD2: Outer diameter of the second tube

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated concretely with reference to drawings. Fig. 1 is a perspective view showing the configuration of a return bend tube, Fig. 2 is a partially broken front view showing an example of a fin-and-tube type heat exchanger assembled with a return bend tube, and Fig. 3 (a) is a heat exchanger of Fig. 2. Is a perspective view of the return bend tube, (b) is a perspective view of the heat exchanger from the hairpin tube side, (c) is a schematic diagram schematically showing the flow of the refrigerant in the heat exchanger, and FIG. 4 is an example of a junction portion of the hairpin tube and the return bend tube. 5 is an enlarged cross sectional view of the return bend tube, (b) is a partially enlarged cross sectional view of (a), and FIG. 6 (a) is a cutaway view of the hairpin tube. (B) is a partial enlarged sectional view of (a), (a), (b) is a schematic diagram which shows schematically the flow of a refrigerant | coolant in the heat exchanger of another embodiment, (a) of FIG. Is a schematic diagram of a suction type wind tunnel used when measuring the evaporation performance of a heat exchanger, (b) is the suction of (a) It is a schematic diagram of a refrigerant | coolant supply apparatus which supplies a refrigerant | coolant to a doll wind tunnel.

(1) return bend pipe

First, the return bend tube of this invention is demonstrated. As shown in Figs. 1 to 3, the return bend tube 1 of the present invention is used in a fin-and-tube type heat exchanger (hereinafter referred to as a heat exchanger) 20, in which a refrigerant is supplied inside the tube. It is joined to the tube end of the hairpin tube 11. The return bend tube 1 includes a tube body portion 1a formed in a U shape, a tube end portion 1b connected to the hairpin tube 11 at a tube end portion of the tube body portion 1a, and a tube pattern. A plurality of first grooves 2 formed on the inner surface of the body part 1a are provided (refer to FIG. 4 and description of the first grooves in FIG. 1 is omitted). This return bend pipe 1 is interposed between two hairpin pipes 11 and 11, and in order to connect hairpin pipes 11 with each other, as shown in FIG. ) Is connected in series to form a long refrigerant path.

As shown in Figs. 5 and 6, the return bend tube 1 restricts the inner grooves of the first grooves 2 formed on the inner side of the tube as follows, whereby the return bend tube 1 is assembled. Evaporation performance as the heat exchanger 20 (refer FIG. 2, FIG. 3) can be improved. In addition, since 3 mm-10 mm of return bend pipe | tube 1 are used as the pipe outer diameter (2nd pipe outer diameter (OD2)) of the hairpin pipe 11 to join, the pipe outer diameter [1st pipe outer diameter (OD1) is used. It is preferable to use the same 3 mm-10 mm tube as this hairpin tube.

<Inner groove shape>

The first groove 2 of the return bend tube 1 is formed of the first groove pitch P1 in the cross section perpendicular to the tube axis and the spiral second groove 12 formed on the inner surface of the tube of the hairpin tube 11. The groove pitch ratio P1 / P2 of the second groove pitch P2 in the tubular orthogonal cross section satisfies 0.65 to 2.2, and the first per groove in the tubular orthogonal cross section of the first groove 2. The groove cross-sectional area ratio S1 / S2 of the groove cross-sectional area S1 and the second groove cross-sectional area S2 per groove in the tubular orthogonal cross section of the second groove 12 needs to satisfy 0.3 to 3.6. The groove cross-sectional area ratio S1 / S2 is more preferably 0.54 to 2.7. The reason for numerical limitation of the groove pitch ratio P1 / P2 and the groove cross-sectional area ratio S1 / S2 is described below.

[Groove pitch ratio (P1 / P2): 0.65 to 2.2]

When the groove pitch ratio P1 / P2 is less than 0.65, the number of grooves of the return bend tube 1 occupying per groove of the hairpin tube 11 increases, thereby increasing the number of grooves from the hairpin tube 11 to the return bend tube 1. When the liquid refrigerant flows in, axial flow occurs in the refrigerant liquid film inside the tube (first groove 2) on the return bend tube inlet side, and the refrigerant liquid film is disturbed. Then, when the liquid refrigerant flows into the hairpin tube 11 of the next stage, the refrigerant liquid film flows in a state where the refrigerant liquid film is disturbed, and a thick portion is formed in the refrigerant liquid film in the straight pipe portion of the hairpin tube, resulting in unstable heat exchange with the outside of the tube. Evaporation performance is reduced.

When the groove pitch ratio P1 / P2 exceeds 2.2, when the liquid refrigerant flows into the return bend tube 1 from the hairpin tube 11, the return bend tube 1 occupies one groove of the hairpin tube 11. The decrease in the number of grooves in the N) decreases significantly the retention of the refrigerant liquid film in the first grooves 2 of the return bend pipe 1, and the formation of the "annular flow" collapses and the refrigerant liquid film is disturbed. Then, when the liquid refrigerant flows into the hairpin tube 11 of the next stage, the refrigerant liquid film is introduced with disturbance, and a thick portion is formed in the refrigerant liquid film in the straight pipe portion of the hairpin tube 11, so that heat exchange with the outside of the tube is prevented. It becomes unstable and evaporation performance falls.

[Groove cross-sectional area ratio (S1 / S2): 0.3 to 3.6]

When the groove cross-sectional area ratio S1 / S2 is less than 0.3, when the liquid refrigerant flows into the return bend tube 1 from the hairpin tube 11, the cross-sectional area of the first groove 2 is greatly reduced, whereby the return bend tube inlet Axial flow of the coolant liquid film occurs on the side, and the coolant liquid film is disturbed. Then, when the liquid refrigerant flows into the hairpin tube 11 of the next stage, the refrigerant liquid film is introduced while the liquid liquid film is disturbed, and a thick portion is formed in the refrigerant liquid film in the straight pipe portion of the hairpin tube 11, whereby heat exchange with the outside of the tube is performed. It becomes unstable and evaporation performance falls.

When the groove cross-sectional area ratio S1 / S2 exceeds 3.6, when the liquid refrigerant flows from the hairpin tube 11 into the return bend tube 1, the resistance decreases due to the increase in the cross-sectional area of the first groove 2. On the contrary, the retention of the refrigerant liquid film in the first groove 2 is lowered, whereby the formation of the "annular flow" collapses and the refrigerant liquid film is disturbed. Then, when the liquid refrigerant flows into the hairpin tube 11 of the next stage, the refrigerant liquid film flows in a state where the refrigerant liquid film is disturbed, and a thick portion is formed in the refrigerant liquid film in the straight pipe portion of the hairpin tube 11, whereby heat exchange with the outside of the tube is prevented. It becomes unstable and evaporation performance falls.

4 to 6, the first groove 2 of the return bend tube 1 includes the first groove lead angle θ1 formed between the first groove 2 and the tube axis, and the hairpin tube. The angle difference θ1-θ2 between the second groove lead angle θ2 formed between the second groove 12 formed on the inner surface of the tube (11) and the tube axis satisfies -15 ° to + 15 °, and the first groove The groove depth ratio h1 / h2 of the first groove depth h1 in the tubular orthogonal cross section of (2) and the second groove depth h2 in the tubular orthogonal cross section of the second groove 12 is 0.47. It is preferable to satisfy to 1.5. In addition, the 1st groove 2 shall also include the case where the 1st groove lead angle (theta) 1 is 0 degrees, ie, the 1st groove 2 is parallel to a tube axis. The reason for numerical limitation of the angle difference θ1-θ2 and the groove depth ratio h1 / h2 will be described below.

[Angle Difference (θ1-θ2): -15 ° to + 15 °]

When the angle difference θ1-θ2 is less than -15 °, that is, the first groove lead angle θ1 is smaller than the [second groove lead angle θ2) -15 °, the first groove on the return bend tube inlet side Splashes of the coolant liquid film are generated starting from the floor of the first fins 3 formed between (2), and disturbance (peeling) occurs in the coolant liquid film. Then, when the liquid refrigerant flows into the hairpin tube 11 of the next stage, the refrigerant liquid film flows in a state where the refrigerant liquid film is disturbed, and a thick portion is formed in the refrigerant liquid film in the straight pipe portion of the hairpin tube 11, whereby heat exchange with the outside of the tube is prevented. It becomes unstable and evaporation performance tends to fall.

When the angle difference θ1-θ2 exceeds + 15 °, that is, the first groove lead angle θ1 is larger than [the second groove lead angle θ2 + 15 °], the return bend tube from the hairpin tube 11 When the liquid refrigerant flows into (1), the pressure loss on the return bend tube side increases, so that axial flow of the refrigerant liquid film occurs on the return bend tube inlet side, and the refrigerant liquid film is disturbed. Then, when the liquid refrigerant flows into the hairpin tube 11 of the next stage, the refrigerant liquid film flows in a state where the refrigerant liquid film is disturbed, and a thick portion is formed in the refrigerant liquid film in the straight pipe portion of the hairpin tube 11, whereby heat exchange with the outside of the tube is prevented. It becomes unstable and evaporation performance tends to fall.

Further, the direction of the first groove lead angle θ1 formed between the first groove 2 and the tube axis is the second groove lead angle formed between the second groove 12 formed in the tube inner surface of the hairpin tube 11 and the tube axis ( It is preferable that it is formed in the same direction as the direction of (theta) 2). If the direction of the first groove lead angle θ1 and the direction of the second groove lead angle θ2 are different, the pressure loss of the refrigerant in the return bend tube 1 becomes large, and the evaporation performance tends to decrease.

[Groove depth ratio (h1 / h2): 0.47 to 1.5]

When the groove depth ratio h1 / h2 is smaller than 0.47, the refrigerant liquid film of the first groove 2 is easily detached from the inlet side of the return bend pipe, splashes of the refrigerant liquid film, and disturbance of the refrigerant liquid film is caused. Occurs. Then, when the liquid refrigerant flows into the hairpin tube 11 of the next stage, the refrigerant liquid film flows in a state where the refrigerant liquid film is disturbed, and a thick portion is formed in the refrigerant liquid film in the straight pipe portion of the hairpin tube 11, whereby heat exchange with the outside of the tube is prevented. It becomes unstable and evaporation performance tends to fall.

When the groove depth ratio h1 / h2 is larger than 1.5, when the liquid refrigerant flows from the hairpin tube 11 into the return bend tube 1, the first fin 3 of the return bend tube 1 becomes a resistor. As a result, axial flow of the refrigerant liquid film occurs at the return bend pipe inlet side, and the refrigerant liquid film is disturbed. Then, when the liquid refrigerant flows into the hairpin tube of the next stage, the refrigerant liquid film is introduced while the liquid film is disturbed, and a thick portion of the refrigerant liquid film is formed in the straight pipe portion of the hairpin tube 11 so that heat exchange with the outside of the tube becomes unstable and evaporates. It is easy to reduce performance.

Moreover, the 1st groove | channel 2 of the 1st fin 3 of the 1st groove | channel 2 formed between the 1st groove | channel 2, and the 1st groove | channel 2 of the return bend pipe | tube 1 and the 1st bone valley radius r1 It is more preferable to form so that it may become equal to the 2nd fin floor angle (delta) 2 of the 2nd fin 13 formed between the 2nd groove | channel 12 of the hairpin tube 11, and the 2nd fin valley radius r2. Do. Further, it is more preferable that the first fin floor angle δ1 is 4.5 ° to 45 °, and the first fin valley radius r1 is 1/12 to 1/2 of the first groove depth h1. Furthermore, it is appropriate that the first fin floor angle δ1 is 4.5 ° to 28.5 °, and the first fin valley radius r1 is 1/12 to 1/4 of the first groove depth h1. As a result, in the return bend pipe 1, formation of the "annular flow" of the refrigerant liquid film is further maintained.

As a result, the evaporation performance of the heat exchanger 20 (see FIG. 2, FIG. 3) is further improved. In the following, the reason for numerical limitation of the first fin floor angle δ1 and the first fin valley radius r1 will be described.

[First Pin Floor Angle (δ1): 4.5 ° to 45 °]

When the first fin floor angle δ1 is less than 4.5 °, when the liquid refrigerant flows from the hairpin tube 11 into the return bend tube 1, the resistance decreases due to an increase in the cross-sectional area of the first groove 2. On the contrary, since the groove bottom width of the first groove 2 becomes wider, the retainability of the coolant liquid film tends to be lowered, and the formation of the "annular flow" tends to collapse, and the coolant liquid film is disturbed. Then, when the liquid refrigerant flows into the hairpin tube 11 of the next stage, the refrigerant liquid film flows in a state where the refrigerant liquid film is disturbed, and a thick portion is formed in the refrigerant liquid film in the straight pipe portion of the hairpin tube 11, whereby heat exchange with the outside of the tube is prevented. It becomes unstable, and evaporation performance falls easily.

Further, when the first fin floor angle δ1 exceeds 45 °, when the liquid refrigerant flows into the return bend tube 1 from the hairpin tube 11, the cross-sectional area of the first groove 2 decreases. As a result, axial flow of the refrigerant liquid film is likely to occur at the inlet side of the return bend tube, and the refrigerant liquid film is disturbed. Then, when the liquid refrigerant flows into the hairpin tube 11 of the next stage, the refrigerant liquid film tends to flow in a state where the refrigerant liquid is disturbed, and a thick portion is formed in the refrigerant liquid film in the straight pipe portion of the hairpin tube 11. Heat exchange becomes unstable, and evaporation performance falls easily.

[First Pin Bone Radius r1: 1/12 to 1/2 of First Groove Depth h1]

When the first fin valley radius r1 becomes less than 1/12 of the first groove depth h1, when the liquid refrigerant flows from the hairpin tube 11 into the return bend tube 1, the first groove 2 The resistance decreases due to the increase in the cross-sectional area, but on the contrary, the groove bottom width of the first groove 2 becomes wider, so that the retention of the refrigerant liquid film tends to be lowered, and the formation of the "cyclic flow" tends to collapse, resulting in disturbance of the refrigerant liquid film. Then, when the liquid refrigerant flows into the hairpin tube 11 of the next stage, the refrigerant liquid film flows in a state where the refrigerant liquid film is disturbed, and a thick portion is formed in the refrigerant liquid film in the straight pipe portion of the hairpin tube 11, whereby heat exchange with the outside of the tube is prevented. It becomes unstable, and evaporation performance falls easily.

In addition, when the 1st fin valley radius r1 exceeds 1/2 of the 1st groove depth h1, when a liquid refrigerant flows into the return bend tube 1 from the hairpin tube 11, a 1st By reducing the cross-sectional area of the groove 2, the axial flow of the refrigerant liquid film is likely to occur at the inlet side of the return bend tube, and the refrigerant liquid film is disturbed. Then, when the liquid refrigerant flows into the hairpin tube 11 of the next stage, the refrigerant liquid film tends to flow in a state where the refrigerant liquid is disturbed, and a thick portion is formed in the refrigerant liquid film in the straight pipe portion of the hairpin tube 11. Heat exchange becomes unstable, and evaporation performance falls easily.

In addition, as shown in FIG. 1, by restricting the tube main body 1a of the return bend tube 1 as follows, the evaporation performance as a heat exchanger in which the return bend tube 1 is assembled can be improved. have.

<Tube body part>

Chieftain (L): 1.0 to 1.5 times the pitch (P)]

It is preferable that the return bend pipe | tube 1 (pipe main-body part 1a) is 1.0-1.5 times the pitch L of the chieftain L. The chieftain L is the distance between the tube end portion 1b and the tube outer surface of the bend end portion in the U-shaped tube body portion 1a. In addition, pitch P is the distance between the centers of both tube ends in the U-shaped tube main-body part 1a.

When the chief L is smaller than 1.0 times the bending pitch P, the length from the return bend tube inlet side to the bending start portion is short, so that the formation of "annular flow" is not sufficient, and the refrigerant inside the bending inside. Turbulence (peel-off) of the refrigerant liquid film occurs due to the splash of the liquid film. Then, when the liquid refrigerant flows into the hairpin tube of the next stage, the refrigerant liquid film flows in a disturbed state, and a thick portion is formed in the refrigerant liquid film in the straight pipe portion of the hairpin tube, so that heat exchange with the outside of the tube becomes unstable, and the evaporation performance is improved. Easy to degrade

When the chieftain L is larger than 1.5 times the bending pitch P, the length from the return bend pipe inlet side to the bend initiation portion becomes long, so that the formation of "annular flow" is facilitated, while in the return bend pipe 1 By increasing the pressure loss, the evaporation performance tends to decrease.

[material]

It is preferable that the material of the return bend tube 1 (tube main body part 1a) is made of the material whose thermal conductivity is lower than the material of a hairpin tube. When the return bend tube 1 is used for the heat exchanger 20 (refer FIG. 2, FIG. 3), especially an air heat exchanger, the return bend tube 1 is used other than a heat exchange part. Therefore, when the material of the return bend tube 1 is higher in thermal conductivity than the material of the hairpin tube, heat loss occurs in the portion of the return bend tube 1. When heat loss occurs in the portion of the return bend tube 1, evaporation of the refrigerant occurs in the portion of the return bend tube 1, the formation of the "cyclic flow" of the refrigerant liquid film collapses, and splashes of the refrigerant liquid film occur. Disturbance (peel-off) of the refrigerant liquid film occurs. Then, when the liquid refrigerant flows into the hairpin tube of the next stage, the refrigerant liquid film flows in a disturbed state, and a thick portion is formed in the refrigerant liquid film in the straight pipe portion of the hairpin tube, so that heat exchange with the outside of the tube becomes unstable, and the evaporation performance is increased. Easy to degrade

Conventionally, phosphorus copper is used as the material of the hairpin tube and the return bend tube 1 (tube main body portion 1a), and a method by soldering is used to connect both tubes. And, when soldering, the tube ends of both pipes are heated to about 800 ° C to 900 ° C with a gas burner or the like. At that time, when phosphorus copper is used for the return bend tube 1 (pipe main body portion 1a), the strength of the return bend tube 1 (heat affected zone) decreases due to this heating, The pressure is likely to break the tube. In order to avoid this, it is necessary to thicken the 1st pipe | tube thickness T1 (refer FIG. 4) of the return bend pipe | tube 1 (pipe main-body part 1a). However, by using a heat-resistant copper alloy that is more heat resistant than the hairpin tube as the material of the return bend tube 1 (tube main body portion 1a), the strength drop due to heating can be avoided, and the pressure resistance is improved. At the same time, increase in thickness can be suppressed. As a result, the weight of the return bend pipe 1 (pipe main body portion 1a) can be reduced. As the heat-resistant copper alloy, for example, copper alloys such as Cu-Sn-P system and Cu-Sn-Zn-P system having a pressure resistance of 10 MPa or more at room temperature even after heating at 850 ° C are preferable. As the hairpin tube, a heat-resistant copper alloy tube of the same material as that of the return bend tube 1 may be used.

[1st maximum internal diameter (ID1)]

As shown to FIG. 5, FIG. 6, the 1st largest internal diameter ID1 of the return bend tube 1 (tube main body part 1a) is compared with the 2nd largest internal diameter ID2 of the hairpin tube 11. As shown in FIG. It is preferable that (ID1) ≥ (ID2) in a relationship. When (ID1) <(ID2) is set, the "circular flow" of the refrigerant liquid film is formed in the pipe of the return bend pipe 1, and when the liquid refrigerant flows into the hairpin pipe 11, it expands. , The coolant liquid film is accumulated in the lower part of the tube, and the thickness of the coolant liquid film is uneven, and the coolant liquid film is disturbed. Then, when the refrigerant liquid film near the inlet of the hairpin tube in the next stage flows in, the thick portion is formed in the refrigerant liquid film, and heat exchange with the outside of the tube is unstable, and the evaporation performance tends to decrease.

(2) hairpin tube

Next, as shown in FIG. 2, FIG. 3, the hair fin tube 11 which comprises the heat exchanger 20 with the return bend tube 1 of this invention is demonstrated. As shown in FIG. 6, it is preferable that the hairpin tube 11 has a plurality of spiral second grooves 12 formed on the inner surface of the tube, and regulates the inner groove shape of the second groove 12 as follows. Do. In addition, since the hairpin tube 11 is a mainstream tube of 3 mm to 10 mm as the heat transfer tube for air conditioning equipment, the tube outer diameter (second tube outer diameter (OD2)) is 3 mm to 10 mm that is the same as that of the hairpin tube. Preference is given to using tubes. Moreover, as the material of the hairpin tube 11, phosphoric acid copper having excellent molding processability is preferable, and a heat resistant copper alloy having better heat resistance than copper phosphorous acid may be used.

[2nd groove pitch P2, 2nd groove cross-sectional area S2]

It is preferable that 2nd groove pitch P2 is 0.37 mm-0.42 mm, and 2nd groove cross-sectional area S2 is 0.04 mm-0.06 mm. In the case where the second groove pitch P2 is less than 0.37 mm and the second groove cross-sectional area S2 is less than 0.04 mm 2, the groove-forming tool (for example, the grooves) is formed when the second groove 12 is formed in the tube inner surface. Due to the decrease in fluidity of the material in the groove portion of the plug), the pushing force from the outside of the tube increases, and as a result, the groove forming tool is likely to be damaged, so that it is stable on the inner surface of the tube and it is difficult to form the second groove 12. In addition, when the second groove pitch P2 exceeds 0.42 mm and the second groove cross-sectional area S2 exceeds 0.06 mm 2, the liquid film of the refrigerant is thinly formed between the second grooves 12 inside the pipe. It's hard to be. Therefore, the refrigerant liquid film inside the tube becomes heat resistance on the contrary, and the evaporation performance tends to decrease.

[2nd groove lead angle (theta) 2: see FIG. 4]

It is preferable that 2nd groove lead angle (theta) 2 is 15 degrees or more. When the second groove lead angle θ2 is less than 15 °, since the formation of the &quot; swirl flow &quot; of the refrigerant liquid film inside the tube is insufficient, the evaporation performance tends to decrease. When liquid refrigerant flows into the hairpin tube 11 of the next stage from the return bend tube outlet side, the formation of uniform "annular flow" of the refrigerant liquid film in the second groove 12 is reduced, and the hairpin tube 11 The refrigerant liquid film in the straight tube portion of the tube becomes uneven, heat exchange with the outside of the tube becomes unstable, and the evaporation performance tends to decrease. Moreover, when the 2nd groove lead angle (theta) 2 exceeds 45 degrees, the speed at the time of forming the 2nd groove 12 in an inner surface of a pipe | tube by a rolling process tends to fall extremely, and it is long long stably. Since the hairpin tube 11 of i) is difficult to manufacture, the second groove lead angle θ2 is more preferably 45 ° or less.

[2nd groove depth (h2)]

It is preferable that the 2nd groove depth h2 is 0.10 mm-0.28 mm. When the second groove depth h2 is less than 0.10 mm, the second fin 13 formed between the second grooves 12 on the inner surface of the tube is lower than the liquid level of the refrigerant in the tube, and is embedded in the refrigerant liquid film. Therefore, the effective heat transfer area inside the tube is significantly reduced, and the evaporation performance is likely to decrease. Moreover, when the 2nd groove depth h2 exceeds 0.28 mm, when forming the 2nd groove 12 in a tube inner surface, a groove forming tool (for example, a plug with a groove | channel) will break easily, It is difficult to form the second groove 12 stably on the inner surface.

[2nd pin floor angle (δ2)]

It is preferable that 2nd fin floor angle (delta) 2 is 5 degrees-45 degrees. When the second fin floor angle δ2 is less than 5 °, the expansion of the second fin 13 at the time of expansion (not shown) when the hairpin tube 11 is assembled to the heat exchanger 20 for an air conditioner. Falling breaks are likely to occur. In addition, when forming the second grooves 12 on the inner surface of the tube for forming the second fin 13, the groove forming tool is likely to be broken, and it is difficult to form the second grooves 12 stably on the inner surface of the tube. In addition, when the 2nd fin floor angle (delta) 2 exceeds 45 degrees, the cross-sectional area of the 2nd groove | channel 12 will become remarkably small, and heat conduction performance will fall easily. Moreover, the cross-sectional area of the 2nd fin 13 (2nd tube thickness T2 of the hair fin tube 11) becomes large, the mass of the hair fin tube 11 increases, and weight reduction of the heat exchanger 20 becomes difficult.

[Second pin goal radius (r2)]

The second fin valley radius r2 is preferably set to 1/10 to 1/3 of the second groove depth h2. When the second fin valley radius r2 is less than 1/10 of the groove depth h2, the formability of the second fin 13 (the second groove 12) when the second fin 13 is raised is high. It becomes worse, and it becomes difficult to obtain the 2nd pin 13 of a predetermined shape, and it becomes easy to generate | occur | produce damage to the groove-forming tool which contacts the trough of the 2nd groove 12 of a pipe inner surface. In addition, when it exceeds 1/3, the cross-sectional area of the 2nd fin 13 becomes large, the 2nd tube thickness T2 of the hairpin tube 11 increases, and the mass of the hairpin tube 11 increases.

[2nd largest inner diameter (ID2)]

The second maximum inner diameter ID2 of the hairpin tube 11 is preferably 0.80 to 0.96 of the outer diameter OD2 of the hairpin tube 11. When the 2nd largest inner diameter ID2 is less than 0.80 of the outer diameter OD2 of the hairpin tube 11, the 2nd tube thickness T2 becomes thick and the mass of the hairpin tube 11 increases and the heat exchanger 20 ) (Refer to FIG. 2, FIG. 3) becomes difficult. In addition, when the 2nd largest inner diameter ID2 exceeds 0.96 of the outer diameter OD2 of the hairpin tube 11, the 2nd tube thickness T2 becomes thin and the tube strength of the hairpin tube 11 becomes low, Tube breakage tends to occur during use of the heat exchanger 20.

(3) Manufacturing method of return bend pipe and hairpin pipe

Next, the manufacturing method of a return bend tube and a hairpin tube is demonstrated. Both tubes of a return bend tube and a hairpin tube are manufactured, for example by the following well-known manufacturing method. A soft material is usually used for the material pipe to which the following 1st process is applied. In addition, following 1st-3rd process is performed continuously using the rolling apparatus provided with the shaft diameter apparatus in the front end and the rear end. After the third shaft diameter processing of the third process, a tube having an inner surface groove is usually wound up with a level winding coil, and annealed in an annealing furnace to be a soft material. Prepare a hairpin tube.

[Step 1]

The raw material tube is subjected to the first shaft diameter processing by drawing a raw material tube made of a raw material such as phosphoric acid copper or a heat resistant copper alloy to pass between the diameter die and the diameter plug.

Second Process

A second shaft diameter processing is performed on the raw material pipe by inserting a grooved plug into the raw material pipe reduced in the first step and pressing a plug having a groove inserted into the raw material pipe with a plurality of rolled balls or rolling rolls. . At the same time, the groove shape of the plug having the groove is transferred to the tube inner surface of the reduced diameter tube, so that the first groove 2 or the second groove 12 (see Fig. 4) is formed. Here, the grooved plug has a groove shape corresponding to the aforementioned inner surface groove shape (see FIGS. 5 and 6).

[Third process]

In the second step, the raw material tube having the first grooves 2 or the second grooves 12 formed on the inner surface of the tube is drawn out by using a die, and the third shaft diameter processing is performed to perform the first tube outer diameter OD1 or the second tube. A heat transfer tube having an inner groove of the tube outer diameter OD2 was manufactured.

[4th process]

A tube having an inner groove formed in the third step is bent with a predetermined jig to produce a return bend tube 1 and a hairpin tube 11 (see FIGS. 1 and 2) having a predetermined shape.

(4) Fin-and-Tube Heat Exchangers

Next, the heat exchanger of this invention is demonstrated. As shown in Figs. 2 and 3 (a), (b) and (c), the heat exchanger 20 is supplied with a refrigerant inside the tube, and a plurality of hair fin tubes 11, 11... Of the hairpin portions 23 parallel to the bend pitch Pa of the joints and the tube ends 1b and 1b (see FIG. 1) to the tube ends of the hairpin tubes 11, 11... Of each of the hairpin portions 23. A plurality of return bends 22, in which a plurality of return bend tubes 1, 1, ... are paralleled, and a plurality of pins 21a, 21a that are parallel to the outer surface of the hairpin tube 11 at a predetermined interval (pin pitch Pb). ... has a pin portion 21 made up of. With this configuration, a plurality of hair fin tubes 11, 11... Are connected in series to the plurality of stages via return bend tubes 1, 1 .. so that the heat exchanger 20 has a long effective heat transfer tube length (refrigerant flow path). Will have As shown in FIG. 3B, the hairpin tube 11 may be arranged in a plurality of rows at a predetermined column direction pitch Pc. Further, as shown in FIG. 3C, the refrigerant supplied into the tube of the heat exchanger 20 is the same direction and refrigerant at the time of condensation of the refrigerant with respect to the flow of air blown into the heat exchanger 20. On evaporation it flows in the reverse direction.

At least one part of the return bend part 22 is comprised by the return bend pipe | tube 1 in which the many 1st groove | channel 2 (refer FIG. 5) was formed in the above-mentioned inner surface of the pipe | tube. In this way, it becomes possible to reduce the deterioration of the evaporation performance in the heat exchanger 20. In addition, the inner groove shape of the return bend pipe 1, for example, the groove pitch ratio P1 / P2, the groove cross-sectional area ratio S1 / S2, the groove depth ratio h1 / h2 (see FIGS. 5 and 6), the groove The return bend part 22 in consideration of the flow angle (upstream or downstream) of the refrigerant | coolant of the heat exchanger 20, etc., or the 1st largest internal diameter ID1, etc., or the 1st largest internal diameter ID1 of lead angle. You may change according to place of). Further, in consideration of the pressure loss of the refrigerant, a return bend tube composed of a smooth tube may be used for at least part of the return bend portion 22.

In addition, the heat exchanger of the present invention may be formed by branching at least a portion of the refrigerant flow passage composed of the hairpin tube and the return bend tube to form a plurality of refrigerant passages. For example, as shown in Figs. 7A and 7B, a two-pass heat exchanger 20A in which the entire refrigerant flow path is branched, and a partial two-pass heat exchanger 20B in which part of the refrigerant flow path branches. ). Here, in FIGS. 7A and 7B, the refrigerant passage is branched into two passages (the refrigerant passage A and the refrigerant passage B), but is not limited to the two passages, but the three passages. It may be branched above. In addition, the branched refrigerant passages (the refrigerant passage A and the refrigerant passage B) may be further branched into the plurality of refrigerant passages. Furthermore, in the partial two-pass heat exchanger 20B of FIG. 7B, one branch may be used, but two or more portions may be used, that is, one pass in which the refrigerant flow path shown in FIG. 3C does not branch. A plurality of two-pass heat exchangers 20A may be coupled to the heat exchanger 20.

In the heat exchanger 20A (two-pass type heat exchanger) and 20B (partial two-pass type heat exchanger) as shown in FIG. 7, the above-mentioned one-pass type heat exchanger 20 (refer to FIG. 3 (c)) Similarly, the evaporation performance is improved by maintaining the swirl flow of the refrigerant, and in the heat exchangers 20A and 20B where the refrigerant flow path is branched, the refrigerant mass velocity per branch is lowered, and in particular, the refrigerant velocity at the inlet side of the return bend tube is reduced. When the liquid refrigerant flows into the hairpin tube of the next stage from the return bend tube outlet side, the "circular flow" of the refrigerant liquid film formed inside the tube is further stabilized. Is formed, the refrigerant liquid film in the straight pipe portion of the hairpin tube becomes uniform, the heat exchange with the outside of the tube (air side) is stabilized, and the evaporation performance is further improved. Flow path B] is formed, whereby The number of stages of the parallel hairpin tube and return bend tube constituting the furnace (refrigerant flow path A or refrigerant flow path B) decreases when compared with the one-pass heat exchanger 20 described above (Fig. 3 (c)). 7 is reduced from 11 to 6 stages.

As a result, the pressure loss of the refrigerant is reduced, and the evaporation performance is further improved.

In addition, the refrigerant used in the heat exchanger 20 of the present invention is a hydrofluorocarbon (HFC) -based refrigerant, preferably an azeotropic mixed refrigerant, for example, an R410-based refrigerant, and difluoromethane (R32) and pentafluoro. R410A in which ethane (R125) is mixed in 50% increments is more preferable. By using the HFC-based azeotropic mixed refrigerant, the evaporation performance of the heat exchanger 20 is improved, and the pressure loss of the refrigerant is also reduced. Moreover, although the R410 system has excellent heat transfer performance, the compressor is large in size because of high operating pressure. Therefore, although the evaporation performance is slightly lower than that of the R410 system, the R407 system having a lower operating pressure than the R410 system may be used as the refrigerant of the present invention.

(Example)

<Examples 1 to 20 (except Example 9)>

EMBODIMENT OF THE INVENTION Hereinafter, the Example of this invention is described concretely.

First, Examples 1 to 6 and Examples 8 to 20 are phosphorus deoxidized copper of alloy number C1220 or anoxic copper of alloy number C1020 as defined in JIS H 3300, and Example 7 is Cu-Sn-P (0.65 mass% Sn, 0.03 The heat-resistant copper alloy (mass% P and remainder of Cu) was melt | dissolved, cast, hot extrusion, cold rolling, cold compression drawing (drawing process), and the raw material pipe was produced. Next, after annealing the said raw material pipe | tube, 1st shaft diameter processing is performed and a 2nd shaft diameter processing is performed, forming the spiral groove | channel (or parallel groove | channel) of the inner-side groove shape shown in Table 1 and Table 2 in the reduced diameter material pipe | tube. The 3rd shaft diameter processing and annealing were performed to the grooved raw material pipe | tube, and the sample pipe (for a return bend pipe) of 7 mm of 1st pipe | tube outer diameter OD1 was produced. Moreover, using the phosphoric acid copper of alloy No. C1220 prescribed | regulated to JISH3300, the sample tube (for hairpin tube) of 7 mm of 2nd pipe outer diameters (OD2) was produced by the same manufacturing method.

Next, using each said sample tube, the fin-and-tube type heat exchanger (one-pass type heat exchanger) 20 shown to FIG. 2, FIG. 3 (a), (b) was produced. First, the sample tube (for a hairpin tube) was bent into a hairpin shape at the predetermined bending pitch Pa at the center part, and the some hairpin tube 11 was produced. Next, a plurality of lines of hairpin tubes 11 were inserted through a plurality of pins 21a arranged in parallel with each other at a predetermined interval (pin pitch Pb). A bullet having a tube diameter of 105.5% based on the outer diameter of the copper tube (hairpin tube 11) is inserted into the hairpin tube 11, and the tube is expanded by a compression type tube expander, and the pin ( 21a) and the hairpin tube 11 were bonded together. Next, the sample tube (for the return bend tube) was bent to a predetermined length L and the pitch P (see FIG. 1) to produce a plurality of return bend tubes 1. And as shown in FIG. 4, the tube end of the adjacent hairpin tube 11 is further expanded, and the return bend tube 1 with the ring of phosphorus lead (BCuP-2) is attached, and both inside the tube While flowing nitrogen gas for oxidation prevention, both tubes were heat-sold (850 degreeC, 1 minute) by the burner, and the heat exchanger 20 was produced. In addition, the specification of the heat exchanger 20 was as follows.

[Heat exchanger 20]

The external shape was made into length 500 mm x height 250 mm x width 25.4 mm.

[Hairpin Tube (11)]

Two rows of 12 stages (bending pitch Pa 21 mm and column direction pitch Pc 13.4 mm) were arranged (foot length La before expansion was about 535 mm).

[Return bend tube (1)]

Chieftain (L) = 20.0 mm, 21.2 mm, 22.5 mm, 31.4 mm, 33.0 mm

Pitch P = 21.0 mm (refer FIG. 1).

[Pin 21a]

In the board | plate material which consists of aluminum of alloy number 1N30 prescribed | regulated to JISH 4000, the surface of a board | plate material is coat | covered with resin. In addition, the thickness of the pin 21a was 110 micrometers. And 410 pins 21a were arrange | positioned in parallel at 1.25 mm of pin pitch Pb.

In addition, Example 9 uses the same sample tube (hair fin tube, return bend tube) as Example 1, and performs the fin-and-tube type heat exchanger shown in FIG. 20 A of 2 pass heat exchangers were produced. In addition, the number of stages of the hairpin tube 11 of the refrigerant | coolant flow paths A and B was 2 rows and 6 stages.

<Comparative Examples 1 to 5>

As shown in Table 3, Comparative Example 1 was the same as in Example 1 except that a smooth tube in which no groove was formed on the inner surface of the tube was used as the sample tube (return bend tube). Comparative Examples 2 to 5 are the same as in Example 1 except that at least one of the groove pitch ratio P1 / P2 and the groove cross-sectional area ratio S1 / S2 uses a tube having an inner surface groove outside the claims of the present invention. Let it go. And the heat exchanger (1-pass type heat exchanger) 20 was produced like Example 1.

Using the heat exchanger of Examples 1-20 and Comparative Examples 1-5, evaporation performance was measured based on JIS C 9612, and the result was shown to Table 1, Table 2, and Table 3. In addition, the evaporation performance measured the amount of heat transfer of the evaporation of each heat exchanger, and described it as the ratio at the time of making comparative example 1 the 1st.

8A is a schematic diagram of a measuring device for measuring evaporation performance. As shown in FIG. 8A, the measuring device includes a suction type wind tunnel 100 having a constant temperature and humidity function, a refrigerant supply device 110 (see FIG. 8B), and an air conditioner (not shown). Is done. In this suction type wind tunnel 100, a heat exchanger 20 (20A) is disposed in a flow path of air flowing from the air inlet 108 and discharged from the air outlet 109, and the heat exchanger 20 (20A). Air samplers 101 and 102 are arranged on the upstream side and the downstream side of the base plate. Temperature and humidity measurement boxes 103 and 104 are connected to the air samplers 101 and 102, respectively. The temperature-humidity measurement boxes 103 and 104 measure the temperature and humidity of this air by measuring the dry bulb temperature and the wet bulb temperature of the air which were collected by the air sampler 101 and 102, respectively. Further, a draw fan 105 is provided downstream of the air sampler 102 to discharge air to the air discharge port 109. In addition, between the heat exchanger 20 (20A) and the air sampler 102, and between the air sampler 102 and the attraction fan 105, a rectifier for rectifying the air passing through the heat exchanger 20 (20A) ( 106 and 106 are provided.

8B, the schematic diagram of the refrigerant | coolant supply apparatus 110 is shown. In Fig. 8B, reference numeral 107 denotes a refrigerant pipe, 111 denotes a sight glass, 112 denotes a liquid (refrigerant) heat and cooling heat exchanger, 113 denotes a dryer, 114 denotes a liquid (coolant) unit, 115 denotes a solution stopper, 116 It is a silver condenser, 117 is an oil separator, 118 is a compressor, 119 is an accumulator, 120 is an evaporator, 121 is an expansion valve, 122 is a flowmeter. Then, through the refrigerant pipe 107, inside the hair fin tube 11 (see FIG. 2) of the heat exchanger 20 (20A) provided in the suction type wind tunnel 100, a refrigerant whose pressure and temperature are adjusted Supplied. In addition, the inlet and the outlet of the heat exchanger 20 (20A) are provided with a pressure gauge 123 (temperature is a saturation temperature corresponding to the measured pressure) for measuring the temperature and pressure of the refrigerant. Furthermore, an air conditioner (not shown) is one for supplying air of controlled temperature and humidity to the air inlet 108 of the suction type wind tunnel 100.

And the measurement conditions were as follows.

<Refrigerant> R22, R410A

<Air side> Dry bulb temperature 27.0 degrees Celsius, wet bulb temperature 19.0 degrees Celsius

Over wind speed of heat exchanger 0.8m / s

<Refrigerant side> Evaporation temperature (outlet basis) 7.5 degreeC, inlet dryness 0.2 degreeC

Outlet superheat 5.0 ℃

TABLE 1

TABLE 2

TABLE 3

From the results of Table 1, Table 2, and Table 3, it was confirmed that the heat exchanger of Examples 1-20 was excellent in the evaporation performance compared with the heat exchanger of Comparative Example 1 which used the smoothing tube as a return bend tube.

In addition, in the heat exchanger of Comparative Example 2, the groove cross-sectional area ratio S1 / S2 is less than the lower limit, and in the heat exchanger of Comparative Example 3, the groove pitch ratio P1 / P2 and the groove cross-sectional area ratio S1 / S2 exceed the upper limit, and the comparison In the heat exchanger of Example 4, since the groove pitch ratio P1 / P2 exceeds the upper limit, and the heat exchanger of Comparative Example 5 has the groove pitch ratio P1 / P2 less than the lower limit, compared with the heat exchangers of Examples 1 to 20, evaporation is performed. The performance was confirmed to be inferior.

<Examples 21 and 22>

As shown in Table 4, Example 21 is a said 1st sample tube (return bend tube) which consists of material Cu-Sn-P (0.65 mass% Sn, 0.03 mass% P, and the heat-resistant copper alloy whose remainder is Cu). It carried out similarly to Example 1 except having used the tube which has an inner surface groove of tube thickness T1 of 0.20 mm.

Example 22 was the same as that of Example 1 except having used the tube which has an internal surface groove | channel of 1st tube thickness T1 as 0.35 mm of said sample tubes (return bend tube). And the heat exchanger (1-pass type heat exchanger) was produced like Example 1. Next, the pressure resistance test by hydraulic pressure was performed using the heat exchanger of Example 1, Example 21, and Example 22. The pressure at the time of breakage in the return bend portion (return bend tube) of the heat exchanger was measured with a Bourdon tube pressure gauge to set the pressure resistance. The results are shown in Table 4.

TABLE 4

Return bend tube Hairpin tube Withstand strength Example 1 Material: C1220 Tube Outer Diameter (OD1): 7.00mm First Tube Thickness (T1): 0.24mm Other Grooves: Same as Table 1 Material: C1220 Tube Outer Diameter (OD2): 7.00mm Second Tube Thickness (T2): 0.24mm Other Groove Specifications: Same as Table 1  13.0Mpa Example 21 Material: Cu-Sn-P Tube Outer Diameter (OD1): 7.00mm First Tube Thickness (T1): 0.20mm Other Grooves: Same as Example 1 Material: C1220 Tube outer diameter (OD2): 7.00 mm Second tube thickness (T2): 0.24 mm Other groove shapes: same as Example 1  13.5Mpa Example 22 Material: C1220 Tube outer diameter (OD1): 7.00 mm First tube thickness (T1): 0.34 mm Other groove shapes: same as Example 1 Material: C1220 Tube outer diameter (OD2): 7.00 mm Second tube thickness (T2): 0.24 mm Other groove shapes: same as Example 1  13.5Mpa

From the results in Table 4, the heat exchanger of Example 21 has a lower breakdown strength than that of Example 1, even if the first pipe thickness T1 of the return bend tube is thinner than that of Example 1. It was confirmed to be high. In addition, in the heat exchanger of Example 22 whose material of a return bend tube was the same as Example 1, although the pressure-resistant strength was equal to Example 21, the 1st tube thickness T1 of a return bend tube becomes 1.7 times as Example 1, In addition, it was confirmed that the usage amount of the material increases.

Claims (10)

A hairpin section in which a plurality of hairpin tubes are parallel, a return bend section in which a plurality of return bend tubes joined to each end of the hairpin tube, and a plurality of pins parallel to the outer surface of the hairpin tube at regular intervals In a fin-and-tube type heat exchanger having a fin portion consisting of a fin and supplied with a refrigerant inside the tube, It has a first groove formed in the inner surface of the tube of the return bend pipe, Groove pitch of 1st groove pitch P1 in the tube-axis orthogonal cross section of a said 1st groove | channel, and 2nd groove pitch P2 in the tube-axis orthogonal cross section of the spiral 2nd groove formed in the pipe | tube inner surface of the said hairpin tube. The ratio P1 / P2 satisfies 0.65 to 2.2, Furthermore, the groove cross-sectional area of the first groove cross-sectional area S1 per groove in the tubular orthogonal cross section of the first groove and the second groove cross-sectional area S2 per groove in the tubular axis orthogonal cross section of the second groove. Characterized in that the ratio (S1 / S2) satisfy 0.3 to 3.6 Fin-and-tube heat exchanger. The method of claim 1, The second groove lead angle θ2 formed between the second groove and the tube axis of the hairpin tube is 15 ° or more. Fin-and-tube heat exchanger. The method of claim 1, At least a portion of the refrigerant passage consisting of the hairpin tube and the return bend tube is branched to form a plurality of refrigerant passages. Fin-and-tube heat exchanger. The method of claim 1, The refrigerant is a non-azeotropic mixed refrigerant of the hydrofluorocarbon system, characterized in that Fin-and-tube heat exchanger. A return bend tube used in a fin-and-tube type heat exchanger, which is joined to a tube end of a hairpin tube having a plurality of fins paralleled at regular intervals on an outer surface thereof and supplied with refrigerant in the tube, It has a first groove formed in the inner surface of the tube of the return bend pipe, Groove pitch of 1st groove pitch P1 in the tube-axis orthogonal cross section of a said 1st groove | channel, and 2nd groove pitch P2 in the tube-axis orthogonal cross section of the spiral 2nd groove formed in the pipe | tube inner surface of the said hairpin tube. The ratio P1 / P2 satisfies 0.65 to 2.2, Furthermore, the groove cross-sectional area of the first groove cross-sectional area S1 per groove in the tubular orthogonal cross section of the first groove and the second groove cross-sectional area S2 per groove in the tubular axis orthogonal cross section of the second groove. Characterized in that the ratio (S1 / S2) satisfy 0.3 to 3.6 Return bend tube. The method of claim 5, wherein The angle difference θ1-θ2 between the first groove lead angle θ1 formed by the first groove and the tube axis, and the second groove lead angle θ2 formed by the second groove and the tube axis is -15 ° to + 15 °. Satisfy Further, the groove depth ratio h1 / h2 of the first groove depth h1 in the tubular orthogonal cross section of the first groove and the second groove depth h2 in the tubular orthogonal cross section of the second groove is 0.47. To satisfy 1.5 to Return bend tube. The method of claim 5, wherein Chieftain (L) of the return bend pipe is characterized in that 1.0 to 1.5 times the pitch (P) Return bend tube. The method of claim 5, wherein The material of the return bend tube is made of a material having a lower thermal conductivity than the material of the hairpin tube Return bend tube. The method of claim 5, wherein The material of the return bend tube is made of a copper alloy having a heat resistance than the material of the hairpin tube Return bend tube. The method of claim 5, wherein The first maximum inner diameter ID1 of the return bend tube is (ID1) ≥ (ID2) in relation to the second maximum inner diameter ID2 of the hairpin tube. Return bend tube.

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