JP2008111624A - Heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent degradation of heat exchanging performance of a heat exchanger caused by heat conduction by preventing heat conduction between heat transfer tubes 4 adjacent to each other, in the heat exchanger 1 of a refrigerant circuit in which a refrigerant, changing its temperature in a heat radiation stroke, flows. <P>SOLUTION: Heat transfer fins 5a respectively between the heat transfer tube 4 of a high temperature-side path h1 and the heat transfer tube 4 of a low temperature-side path h2 adjacent to each other, is divided. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a heat exchanger provided in a refrigerant circuit, and more particularly to the shape of heat transfer fins of a heat exchanger provided in a refrigerant circuit through which a refrigerant that changes in temperature in a heat release stroke flows.

  2. Description of the Related Art Conventionally, there has been known a heat exchanger that includes a heat transfer tube group in which a plurality of heat transfer tubes are arranged, and has refrigerant headers at both ends of the heat transfer tube group. A plurality of refrigerant passages (hereinafter referred to as paths) through which the refrigerant travels between the refrigerant headers in the heat transfer tube group. When the refrigerant reciprocates once through the heat transfer tube group, the heat transfer tube group includes: There are some which are divided into two paths on the return path) and provided with a plurality of heat transfer fins between adjacent heat transfer tubes in the heat transfer tube group (for example, see Patent Document 1).

  Specifically, in order to divide the heat transfer tube group into a plurality of paths, a partition plate that divides the inside of at least one refrigerant header in the length direction is provided in the one refrigerant header. Here, by dividing the refrigerant header by this partition plate, the paths are arranged so as to be adjacent to each other, so that a meandering refrigerant path is formed. Thereby, this heat exchanger can be comprised compactly.

  A plurality of the heat transfer fins are provided outside the tube wall of each heat transfer tube. And the front-end | tip of this heat-transfer fin has reached even the tube wall of the adjacent heat-transfer tube. By comprising in this way, the area of a fin can be enlarged as much as possible and the heat-transfer promotion effect can be heightened more.

By the way, in the refrigerant circuit that performs the above-described vapor compression refrigeration cycle, when carbon dioxide is used as the refrigerant, generally, as shown by the thick line in FIG. And a refrigeration cycle (abcd) having an endothermic process (between da) below the critical temperature. As can be seen from FIG. 6, in the case of the endothermic process, carbon dioxide absorbs heat while undergoing a phase change, so that the refrigerant temperature during the endotherm is constant. On the other hand, in the case of the heat dissipation process, since carbon dioxide includes a portion exceeding the critical temperature (e), the carbon dioxide dissipates heat without causing a phase change. During the heat radiation, the refrigerant temperature changes greatly compared to the above-described heat absorption process (in the example of FIG. 6, the temperature difference ΔT≈50 ° C.). And in order to perform this heat radiation process, it is possible to use the heat exchanger mentioned above.
JP 2006-105415 A

  However, when the heat exchanger is used to perform the heat dissipation process, there is a problem that the heat exchange capability of the heat exchanger is reduced.

  That is, the carbon dioxide flowing inside the pipe of the heat exchanger changes the refrigerant temperature as the heat is radiated, so that a temperature difference occurs between the plurality of paths formed in the heat transfer pipe group, and the high temperature side path and the low temperature A side path is formed. Here, the heat exchanger is disposed so that the paths are adjacent to each other, and a plurality of heat transfer fins are installed between the adjacent heat transfer tubes. For this reason, when the high temperature side path and the low temperature side path are formed, the transfer of the high temperature side path is performed via the heat transfer fins provided between the heat transfer tube of the high temperature side path and the heat transfer pipe of the low temperature side path. Heat transfer due to heat conduction occurs from the heat pipe to the heat transfer pipe of the low-temperature side path. As a result, the heat transfer tube of the low temperature side path is heated, and the refrigerant temperature of the heat transfer tube of the low temperature side path is hardly lowered. That is, the heat exchange capability is reduced.

  This invention is made | formed in view of this point, The objective is suppressing the heat conduction which arises between adjacent heat exchanger tubes in the heat exchanger of the refrigerant circuit through which the refrigerant | coolant which changes temperature in a heat radiation process flows. It is to suppress a decrease in heat exchange capacity of the heat exchanger due to the heat conduction.

  The first invention provides a heat transfer tube group (h) in which a plurality of heat transfer tubes (4) are arranged, a first refrigerant header (2) provided on one end side of the heat transfer tube group (h), and the heat transfer tube. Heat transfer fin (5) provided between the second refrigerant header (3) provided on the other end side of the heat tube group (h) and the adjacent heat transfer tube (4) in the heat transfer tube group (h) And the inside of the pipe of at least one refrigerant header (2, 3) is divided in the length direction so that the heat transfer pipe group (h) is divided into a high temperature side path (h1) and a low temperature side path (h2). On the other hand, it is premised on a heat exchanger in which the partition member (8) is provided and the refrigerant flowing inside the heat transfer tube (4) changes its temperature. Examples of the refrigerant include supercritical carbon dioxide.

  The heat transfer fin (5) of the heat exchanger is at least between the heat transfer tube (4) of the high temperature side path (h1) adjacent to the heat transfer tube (4) of the low temperature side path (h2). It is characterized in that a heat conduction inhibiting means for preventing heat conduction is provided.

  In the first invention, heat conduction is inhibited in the heat transfer fin (5a) between the heat transfer tube (4) of the adjacent high temperature side path (h1) and the heat transfer tube (4) of the low temperature side path (h2). By providing the means, heat conduction from the heat transfer tube (4) of the high temperature side path (h1) to the heat transfer tube (4) of the low temperature side path (h2) can be prevented. Thereby, it can prevent that the heat exchanger tube (4) of a low temperature side path (h2) is heated by the heat exchanger tube (4) of a high temperature side path (h1).

  According to a second invention, in the first invention, the heat transfer fin (5) is provided with a heat conduction inhibiting means for preventing heat conduction between all adjacent heat transfer tubes (4). It is said.

  In the second invention, unlike the first invention, the heat transfer fin (4) between the heat transfer tube (4) of the adjacent high temperature side path (h1) and the heat transfer tube (4) of the low temperature side path (h2) Rather than providing heat conduction inhibition means only in 5a), by providing heat conduction inhibition means on the heat transfer fins (5) between all adjacent heat transfer tubes (4), the heat exchanger (1) All the heat transfer fins (5) can be configured with fins having the same shape.

  According to a third aspect of the present invention, in the first or second aspect, the heat conduction inhibiting means cuts the heat transfer fin (5) between the adjacent heat transfer tubes (4) as a whole (10) It is characterized by comprising.

  In 3rd invention, the said heat-transfer fin (5) is divided | segmented entirely and the heat conduction between adjacent heat-transfer tubes (4) can be prevented by isolate | separating adjacent heat-transfer tubes (4). .

  According to a fourth aspect of the present invention, in the first or second aspect, the heat conduction-inhibiting means partially cuts the heat transfer fin (5) between the adjacent heat transfer tubes (4) (20) It is characterized by comprising.

  In the fourth invention, unlike the third invention, the heat transfer fin (5) is not divided entirely but partially. Here, as a structure which partly divides | segments, the structure which leaves a slit-shaped cut | interruption leaving both ends, for example is mentioned. Thereby, the heat conduction between the adjacent heat transfer tubes (4) can be prevented without completely separating the adjacent heat transfer tubes (4).

  A fifth invention is characterized in that, in the first or second invention, the heat conduction inhibiting means is made of a material (30) having a lower thermal conductivity than the heat transfer fin (5). .

  In the fifth invention, unlike the third or fourth invention, the heat transfer fin (5) is not divided entirely or partially but has a lower thermal conductivity than the heat transfer fin (5). By providing the material (30) having the intermediate portion of the heat transfer fin (5), heat conduction between the adjacent heat transfer tubes (4) can be prevented. Thereby, the heat conduction between the adjacent heat transfer tubes (4) can be prevented without the heat transfer fins (5) being partially or partially divided.

  According to the present invention, heat conduction inhibiting means is provided on the heat transfer fin (5a) between the heat transfer tube (4) of the adjacent high temperature side path (h1) and the heat transfer tube (4) of the low temperature side path (h2). By providing, it is possible to prevent the heat transfer tube (4) of the low temperature side path (h2) from being heated by the heat transfer tube (4) of the high temperature side path (h1), so in the heat exchanger (1) A decrease in heat exchange capability can be suppressed. Here, the heat conduction inhibiting means is limited to the heat transfer fin (5a) between the heat transfer tube (4) of the adjacent high temperature side path (h1) and the heat transfer tube (4) of the low temperature side path (h2). The reason is that the heat transfer fin (5a) has the largest temperature difference at both ends of the heat transfer fin (5) of the heat exchanger (1), and the heat transfer due to heat conduction is large. Because it is. Then, by providing the heat transfer fin (5a) with the heat conduction inhibiting means, it is possible to more effectively suppress a decrease in the heat exchange capability in the heat exchanger (1).

  According to the second invention, only the heat transfer fin (5a) between the heat transfer tube (4) of the adjacent high temperature side path (h1) and the heat transfer tube (4) of the low temperature side path (h2) is divided. Instead, all heat transfer fins (5) between adjacent heat transfer tubes (4) in the same path (h1, h2) are also divided. That is, the heat transfer fins (5) constituting the heat exchanger (1) all have the same shape. Thereby, when manufacturing the heat exchanger (1), it is not necessary to select the heat transfer fin (5), so that the manufacturing process can be simplified, and the heat exchanger (1) can be reduced. Cost can be reduced.

  According to 3rd invention, the said heat-transfer fin (5) is divided | segmented entirely, and heat conduction between adjacent heat-transfer tubes (4) is prevented by isolate | separating adjacent heat-transfer tubes (4). Therefore, it is possible to reliably suppress a decrease in heat exchange capacity in the heat exchanger (1).

  According to the fourth invention, since the heat transfer between the adjacent heat transfer tubes (4) can be prevented by partially dividing the heat transfer fin (5), the heat exchanger (1) It can suppress that the heat exchange capability in falls. In addition, since the heat transfer fin (5) is partially divided, a communication portion remains between the heat transfer fin (5) and the heat transfer tube (4), and the heat transfer fin (5) is entirely removed. Compared with the case where it divides automatically, the strength reduction of the heat exchanger (1) can be prevented.

  According to 5th invention, by providing the material (30) which has lower heat conductivity than this heat-transfer fin (5) in the intermediate part of the said heat-transfer fin (5), adjacent heat-transfer pipe | tube (4) Therefore, it is possible to prevent the heat exchange capability of the heat exchanger (1) from decreasing. Further, since the heat transfer fin (5) is not divided in whole or in part, the strength of the heat exchanger (1) can be further prevented from being lowered.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The heat exchanger (1) of this embodiment is connected to a refrigerant circuit that performs a vapor compression refrigeration cycle using carbon dioxide as a refrigerant, and carbon dioxide and air compressed to a supercritical pressure in the refrigerant circuit. And the carbon dioxide is cooled.

-Heat exchanger configuration-
FIG. 1 is a perspective view conceptually showing the external shape of the heat exchanger (1). As shown in the figure, the heat exchanger (1) includes a heat transfer tube group (h) in which a plurality of heat transfer tubes (4) are arranged, and refrigerant headers provided at both ends of the heat transfer tube group (h) ( 2, 3) and a plurality of heat transfer fins (5) arranged between the adjacent heat transfer tubes (4) in the heat transfer tube group (h) and arranged in the tube axis direction of the heat transfer tubes (4) And.

<Heat transfer tube group>
As shown in FIG. 1, the heat transfer tube group (h) has the tube axis directions of the heat transfer tubes (4) parallel to each other, and the heat transfer tubes (4) are arranged in a line in the vertical direction at a predetermined interval. It is configured by arranging. Here, the reason why the predetermined interval is provided between the heat transfer tubes (4) is to allow air to smoothly flow outside the tubes. Further, the heat transfer tube (4) has a flat cross section as shown in an enlarged cross-sectional view of part A of FIG. 1 in FIG. 2, and a plurality of rectangular small tubes for allowing carbon dioxide to flow in the tube. A hole (4a) is provided.

<Refrigerant header>
The refrigerant header (2, 3) includes a first refrigerant header (2) connected to one end side (right side in the figure) of the heat transfer tube group (h), and the other end side of the heat transfer tube group (h) ( It is comprised with the 2nd refrigerant | coolant header (3) connected to the left side of the figure. In addition, openings are provided on the upper and lower surfaces of the first refrigerant header (2). A refrigerant inlet port (6) is connected to the opening on the upper surface, and a refrigerant outlet port (7) is connected to the opening on the lower surface. Furthermore, a partition plate (partition member) (8) that divides the first refrigerant header (2) up and down is provided at an intermediate position in the pipe of the first refrigerant header (2). In this way, by configuring the first and second refrigerant headers (2, 3), the heat transfer tube group (h) is adjacent to both sides of the partition plate (8) as a boundary. Divided into a first path (high temperature side path) (h1) and a second path (low temperature side path) (h2), a two-pass refrigerant flow path in which the refrigerant reciprocates once is formed.

<Heat transfer fin>
As shown in FIG. 1, the heat transfer fin (5) is provided such that both ends of the heat transfer fin (5) are in contact with the tube walls of the heat transfer tubes (4) on both sides. Further, the heat transfer fins (5) are arranged so that the rectangular space between adjacent heat transfer tubes (4) in the heat transfer tube group (h) is divided into a plurality of continuous triangular small spaces. It is arranged at an angle.

  Further, as shown in FIG. 2, the heat transfer fin (5) is a rectangular plate-like fin (5), and an intermediate portion thereof is divided in the longitudinal direction. This divided part constitutes the heat conduction inhibiting means of the present invention. A plurality of slits (9) are also provided in the short direction.

-Heat exchanger operation-
The heat exchanger (1) is used in a refrigerant circuit that performs a vapor compression refrigeration cycle using carbon dioxide as a refrigerant, and performs a heat radiation process (between bc in FIG. 6) of the refrigeration cycle. It is configured.

  First, the flow of carbon dioxide in the heat exchanger (1) will be described. In addition, the arrow of FIG. 1 has shown the flow of the carbon dioxide. High-temperature carbon dioxide compressed to a supercritical pressure by a compressor (not shown) provided in the refrigerant circuit passes through the first refrigerant header (2) of the heat exchanger (1) from the refrigerant inlet port (6). ) Flows into the upper part (2a). A part of the carbon dioxide flowing into the upper part (2a) of the first refrigerant header (2) collides with the partition plate (8) provided in the first refrigerant header (2), and all the carbon dioxide The heat transfer tube group (h) is divided into each heat transfer tube (4) in the first path (h1).

  The carbon dioxide flowing into each heat transfer tube (4) of the first path (h1) exchanges heat with the air flowing outside the tube, radiates heat to the air, and the temperature of the carbon dioxide itself decreases. Carbon dioxide passes through the first path (h1) with heat dissipation, and then flows into and merges with the second refrigerant header (3). The carbon dioxide merged above the second refrigerant header (3) is diverted again below the second refrigerant header (3) and flows into the heat transfer tubes (4) of the second path (h2). The carbon dioxide flowing into each heat transfer tube (4) in the second path (h2) again exchanges heat with the air flowing outside the tube, radiating heat to the air, and the temperature of the carbon dioxide itself also drops. Go. Then, after passing through the second path (h2) with heat dissipation, the carbon dioxide flows into the lower part (2b) of the first refrigerant header (2), joins, and flows out from the refrigerant outlet port (7). .

  On the other hand, the air flow in the heat exchanger (1) passes through a plurality of continuous triangular small spaces provided between adjacent heat transfer tubes (4) of the heat transfer tube group (h). Become a flow. And when passing through this small space, heat exchange is performed with carbon dioxide flowing inside the tube, and the air is heated. Here, since the heat transfer fin (5) is provided with a plurality of slits (first slits) (9) in the short direction, the air flowing through the small space is secondary by the slit (9). This causes a flow and promotes heat transfer on the air side.

-Effect of the embodiment-
In this embodiment, by dividing the heat transfer fin (5a) between the heat transfer tube (4) of the adjacent high temperature side path (h1) and the heat transfer tube (4) of the low temperature side path (h2), It is possible to prevent the heat transfer tube (4) of the low-temperature side path (h2) from being heated by the heat transfer tube (4) of the side path (h1). Thereby, the fall of the heat exchange capability in the said heat exchanger (1) can be suppressed.

-Modification 1 of embodiment-
In the first modification of the embodiment, only the heat transfer fin (5a) between the heat transfer tube (4) of the first pass (h1) and the heat transfer tube (4) of the second pass (h2) is cut off. Instead, as shown in FIG. 3, all the heat transfer fins (5) between adjacent heat transfer tubes (4) in the same path (h1, h2) are also divided. That is, the heat transfer fins (5) constituting the heat exchanger (1) all have the same shape. Thereby, when manufacturing the heat exchanger (1), it is not necessary to select the heat transfer fin (5), so that the manufacturing process can be simplified, and the heat exchanger (1) can be reduced. Cost can be reduced.

-Modification 2 of embodiment-
In the second modification of the embodiment, the heat transfer fin (5) is not divided as a whole, but the second slit (20) is provided in addition to both end portions as shown in FIG. Thereby, since a communication part remains between the both ends of the heat transfer fin (5) and the heat transfer tube (4), compared to the case where the heat transfer fin (5) is entirely divided, Heat conduction between adjacent heat transfer tubes (4) can be suppressed while preventing a decrease in strength of the heat exchanger (1). Further, since the second slit (20) is provided, a secondary flow can be caused in the air flowing outside the tube, so that heat transfer on the air side can be promoted.

—Modification 3 of Embodiment—
In the third modification of the embodiment, the heat transfer fin (5) is not provided with the second slit (20), but as shown in FIG. 5, a low heat conductive member having a lower thermal conductivity than the heat transfer fin (5). (30) is interposed. Thereby, since it is not necessary to cut | disconnect the said heat-transfer fin (5), the heat conduction between adjacent heat-transfer tubes (4) is prevented, further preventing the fall of the intensity | strength of the said heat exchanger (1). be able to.

<< Other Embodiments >>
About the said embodiment, it is good also as the following structures.

  In the above embodiment, the heat transfer tube (4) of the heat exchanger (1) has a flat cross section, and a plurality of small rectangular holes (4a) are provided in the tube (4 However, it is not necessary to use the flat heat transfer tube (4), and it may be a circular tube.

  Moreover, although the heat exchanger (1) of the said embodiment was comprised with the heat exchanger (1) of 2 passes, it does not necessarily need to be 2 passes and may be 3 passes or more. Here, in the case of three passes, a partition plate is also provided in the second refrigerant header (3), and carbon dioxide passes between the two refrigerant headers (2, 3) through the forward path, the backward path, and the forward path. (3) will flow out.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

  As described above, the present invention is useful for the shape of the heat transfer fins of a heat exchanger suitable for use in a refrigerant circuit in which a refrigerant that changes in temperature during a heat release stroke flows.

It is the perspective view which showed the external appearance shape of the heat exchanger in embodiment of this invention. It is an expanded sectional view of the A section in FIG. It is sectional drawing to which some heat exchangers in the modification 1 of embodiment of this invention were expanded. It is sectional drawing which expanded a part of heat exchanger in the modification 2 of embodiment of this invention. It is sectional drawing to which some heat exchangers in the modification 3 of embodiment of this invention were expanded. It is the figure which represented the refrigerating cycle on the TS diagram of a carbon dioxide.

Explanation of symbols

1 Heat exchanger
2 First refrigerant header
3 Second refrigerant header
4 Heat transfer tube
5 Heat transfer fin
6 Refrigerant inlet port
7 Refrigerant outlet port
8 Partition plate (partition member)
10 Dividing part
20 Second slit
30 Low thermal conductivity member
h Heat transfer tube group
h1 1st pass (High temperature side pass)
h2 Second pass (low temperature side pass)

Claims (5)

A heat transfer tube group (h) in which a plurality of heat transfer tubes (4) are arranged, a first refrigerant header (2) provided on one end side of the heat transfer tube group (h), and the heat transfer tube group (h) A second refrigerant header (3) provided on the other end side, and a heat transfer fin (5) provided between adjacent heat transfer tubes (4) in the heat transfer tube group (h),
A partition member that divides the pipe of at least one refrigerant header (2, 3) in the length direction so that the heat transfer pipe group (h) is divided into a high temperature side path (h1) and a low temperature side path (h2). 8) is a heat exchanger in which the refrigerant flowing inside the heat transfer tube (4) changes its temperature,
The heat transfer fin (5) has heat conduction that hinders heat conduction between at least the heat transfer tube (4) in the high-temperature side path (h1) and the heat transfer tube (4) in the low-temperature side path (h2). A heat exchanger characterized in that an obstruction means is provided. In claim 1,
The heat exchanger, wherein the heat transfer fin (5) is provided with heat conduction inhibiting means for preventing heat conduction between all adjacent heat transfer tubes (4). In claim 1 or 2,
The heat exchanger is characterized by comprising a cut surface (10) that divides the heat transfer fin (5) between the adjacent heat transfer tubes (4) as a whole. In claim 1 or 2,
The heat conduction inhibiting means comprises a cut surface (20) that partially divides the heat transfer fin (5) between the adjacent heat transfer tubes (4). In claim 1 or 2,
The heat exchanger is characterized by comprising a material (30) having a lower thermal conductivity than the heat transfer fin (5).

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