JP2008275303A - Heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger having superior heat exchanging efficiency and a small pressure loss during frosting. <P>SOLUTION: The heat exchanger 100 is equipped with a heat transfer tube 33 for distributing a refrigerant inside the heat exchanger 100, and a plurality of fins 31 aligned in parallel to each other to form an air flow passage on the outside of the heat transfer tube 33. Louvered parts 111, 121, 131 are provided on the surface of the fins 31 for promoting heat exchange by applying change of the air flow direction. Each of the louvered parts 111, 121, 131 extends diagonally from a fin 31 toward another fin 31 adjacent to the fin 31 where it is provided. Heights H<SB>1</SB>, H<SB>2</SB>, H<SB>3</SB>of the louvered parts 111, 121, 131 are equal to a gap P between a pair of fins 31, 31 adjacent to each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat exchanger, and more particularly to a heat exchanger used as an evaporator in a heat pump.

  Heat exchangers used as evaporators for air conditioners and water heaters are arranged in parallel to each other with a plurality of heat transfer tubes arranged in parallel in a plurality of rows, with a space for air flow, and the heat transfer tubes pass And a plurality of plate-like fins that cross and are coupled to the heat transfer tube. The refrigerant flowing in the heat transfer tube crosses the longitudinal direction of the heat transfer tube through the heat transfer tube and the fin, that is, exchanges heat with the air blown by the blower along the fin plate surface.

  As in Patent Document 1 and Patent Document 2, the fin surface is cut and raised obliquely (louver), or as in Patent Document 3 and Patent Document 4, the fin surface is cut and raised in parallel ( By providing a slit), heat exchange between air and fins can be promoted.

  For example, the fin of Patent Document 1 has a stepped louver 72 as shown in FIG. 9A. A bent air flow path is formed between one fin 70 and another fin 70. According to such an air flow path, since the development of the boundary layer can be suppressed, the heat transfer performance of the fin is improved. However, since the tip of the louver 72 is located between the fin 70 and the fin 70, the frost 75 is concentrated on the tip of the louver 72 under the condition that frost is formed on the fin 70 as shown in FIG. 9B. The air flow path may be blocked. Fins (heat exchangers) having such problems are essentially unsuitable for use at low temperatures.

  In response to such a problem, in Patent Document 2, the louver is not provided in the fin close to the air inflow portion where frost formation is likely to occur, and the louver is provided in a portion close to the air outflow portion, thereby blocking the air flow path due to frost formation. Is delayed.

  In patent document 3, the blockage | closure of the air flow path by frost formation is delayed by restraining the cut-and-raised height of a slit low.

In Patent Document 4, the slits are provided stepwise to delay the blockage of the air flow path due to frost formation.
Japanese Patent Laid-Open No. 60-30999 Japanese Patent Laid-Open No. 10-220977 JP 2002-243383 A JP 2006-258383 A

  However, if it is set as patent document 2, depending on inflow air conditions and refrigerant | coolant conditions, frost formation may concentrate on the part near an air outflow part. As a result, the air flow path in the vicinity of the air outflow portion is abruptly blocked, preventing efficient heat exchange.

  Furthermore, if it is set as the structure like patent document 3, when the clearance gap between the base material which produced | generated the slit and the slit is obstruct | occluded by frost formation, an air pressure loss will rise and an air flow rate will fall. At the same time, since the leading edge portion of the fin disappears, the heat transfer coefficient is significantly reduced.

  Moreover, if it is set as the structure like patent document 4, since it is necessary to provide very many slits in the step shape from the upstream to the downstream with respect to an air flow, a more precise process will be needed than before. Further, as the number of slits increases, the rigidity of the fins decreases and assembly becomes difficult. Further, there is a problem that the air pressure loss increases as the number of slits increases.

  Of course, the fact that frost adheres to the fins is also evidence that efficient heat exchange is performed, so it is important to suppress the increase in pressure loss as much as possible while allowing frost formation. Furthermore, it is also important that the processing and assembly be easy in order to prevent variations in performance from product to product and to achieve stable performance. An object of this invention is to provide the novel heat exchanger which can respond to such a request | requirement.

That is, the present invention
A heat exchanger for exchanging heat between the first fluid and the second fluid,
A heat transfer tube for circulating the first fluid inside, and a plurality of fins arranged in parallel to each other so that the flow path of the second fluid is formed outside the heat transfer tube,
Each of the surfaces of the plurality of fins is provided with a cut and raised to promote heat exchange between the first fluid and the second fluid by changing the flow direction of the second fluid,
The cut and raised portion extends obliquely toward another fin adjacent to the fin having the cut and raised portion,
Provided is a heat exchanger in which the height of the cut and raised is equal to the interval between the pair of adjacent fins.

In another aspect, the present invention provides:
A heat exchanger for exchanging heat between the first fluid and the second fluid,
A heat transfer tube for circulating the first fluid inside, and a plurality of fins arranged in parallel to each other so that the flow path of the second fluid is formed outside the heat transfer tube,
Each of the plurality of fins is provided with a cut and raised portion for promoting heat exchange between the first fluid and the second fluid by changing the flow direction of the second fluid. A flat portion that is not a portion,
The cut and raised is inclined with respect to the flat portion so as to extend obliquely toward another fin adjacent to the fin having the cut and raised,
Allowing the second fluid to flow from the flow path on the first side of the fin to the flow path on the second side of the fin adjacent to the upstream end of the cut and raised in the flow direction of the second fluid Gap is formed,
Provided is a heat exchanger in which a height from a surface of the flat portion to an upstream end of the cut and raised is equal to a distance between a pair of adjacent fins.

  According to the heat exchanger of the present invention, the height of the cut and raised coincides with the interval between the fins. Thereby, at the time of non-frosting, the leading edge effect can be obtained at the tip of the cut and raised (upstream end), and further, the heat transfer coefficient on the surface of the fin is improved by changing the flow direction of the second fluid, Efficient heat exchange is possible. On the other hand, at the time of frost formation, even if clogging occurs at the leading end of the cut and raised, it is possible to avoid the blockage of the flow path of the second fluid, and it is possible to suppress an increase in pressure loss. After clogging, a flow path having the same shape as that of a conventional corrugated fin can be formed. Since the flow direction of the second fluid can be changed, a decrease in the heat transfer coefficient on the surface of the fin can also be suppressed. Thus, according to the present invention, it is possible to realize a heat exchanger that can obtain a high heat transfer coefficient and can suppress an increase in ventilation resistance during frost formation. Further, since the height of the cut and raised is made to coincide with the interval between the fins, the size of one cut and raised becomes relatively large. Therefore, processing and assembly are also easy.

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

  FIG. 1 is an external view of a heat exchanger according to an embodiment of the present invention. FIG. 2 is a partial plan view of the fins of the heat exchanger shown in FIG. 3 is a cross-sectional view taken along the line A-A ′ of FIG. 2.

  As shown in FIG. 1, the heat exchanger 100 of this embodiment includes a plurality of plate-like fins 31 arranged in parallel at a predetermined interval P (hereinafter referred to as fin pitch P), and these fins 31. And a heat transfer tube 33 inserted into the through hole. A large number of flow paths for circulating air (second fluid) are formed between the fins 31 and 31. Heat exchange is performed between the air flowing through these flow paths and the refrigerant (first fluid) flowing inside the heat transfer tube 33.

  In the heat exchanger 100, the arrangement direction of the fins 31 is defined as the Z direction, the arrangement direction of the heat transfer tubes 33 inserted into the fins 31 is defined as the Y direction, and the direction orthogonal to the Z direction and the Y direction is defined as the X direction. The Z direction coincides with the thickness direction of the fin 31. The Y direction coincides with the longitudinal direction of the fin 31. The air is guided to the heat exchanger 100 so as to proceed in parallel to the X direction, and flows along the X direction through a flow path formed between the fins 31 and 31.

  The fin 31 is made of a thin and long aluminum plate. In the present embodiment, the fins 31 are arranged in two rows in the front-rear direction with respect to the X direction. The fins 31 constituting the front row portion 3 and the fins 31 constituting the rear row portion 5 are shifted by a half pitch (P / 2) with respect to the Z direction. Thereby, also in the back row part 5, the same front edge effect as the front row part 3 is acquired.

  The heat transfer tube 33 is inserted into the through hole of the fin 31 so that the longitudinal direction of the heat transfer tube 33 coincides with the Z direction. The heat transfer tube 33 is typically made of a metal having excellent thermal conductivity, such as copper or a copper alloy. The heat transfer tubes 33 constituting the front row portion 3 and the heat transfer tubes 33 constituting the rear row portion 5 may be in a staggered arrangement or a lattice arrangement. Further, the heat transfer tube 33 may be formed by connecting a plurality of heat transfer tubes, or may be formed by bending one heat transfer tube.

  As shown in FIG. 2, the plurality of fins 31 have louvers 111, 121, 131 (cut and raised), a collar 11, and a flat portion 35, respectively. The louvers 111, 121, 131 are for promoting heat exchange between the air flowing between the fins 31 and the fins 31 and the refrigerant flowing inside the heat transfer tubes 31 by changing the flow direction of the air. It is. The flat portion 35 is a portion where the louvers 111, 121, and 131 are not formed, and has a surface parallel to the XY plane. The collar 11 is formed so as to rise along the outer peripheral surface of the heat transfer tube 33, and functions as a support member that maintains the distance between adjacent fins 31 by being in close contact with the heat transfer tube 33. A heat transfer tube 33 is inserted into the through hole surrounded by the collar 11.

  As shown in FIG. 3, the louvers 111, 121, 131 have a flat portion 35 that extends obliquely toward another fin 31 adjacent to the fin 31 on which the louvers 111, 121, 131 are provided. Is inclined. In other words, the louvers 111, 121, 131 are inclined with respect to the XY plane. Ventilation gaps 113, 123, 133 are formed adjacent to the upstream ends of the louvers 111, 121, 131 in the air flow direction (X direction). Through the ventilation gaps 113, 123, and 133, air can flow from a flow path formed on the upper side or lower side of any fin 31 to a flow path formed on the lower side or upper side of the arbitrary fin 31.

Heights H ₁ , H ₂ , H ₃ from the surface of the flat portion 35 to the tips (upstream ends) of the louvers 111, 121, 131 are equal to the distance P between the fins 31. In other words, the louvers 111, 121, 131 are designed so that the heights H ₁ , H ₂ , H ₃ coincide with the interval P between the fins 31. Therefore, as will be described later with reference to FIG. 6, even if frost adheres to the tips of the louvers 111, 121, 131 to some extent, the air flow path is not blocked, and excessive pressure loss can be prevented.

Note that “matching” does not necessarily mean complete matching. Even if there is a difference between the heights H ₁ , H ₂ , H ₃ and the distance P, it is included in the “match” if it is within the range of tolerance that inevitably occurs in the manufacturing process of the heat exchanger It is.

  Both end portions 112, 122, 132 of the louver 111, 121, 131 are connected to the flat portion 35, and the louver 111, 121, 131 is fixed to the flat portion 35 by the both end portions 112, 122, 132. The position where the louvers 111, 121, 131 are formed is a region between two heat transfer tubes 33, 33 adjacent to each other in the Y direction. That is, the louvers 111, 121, 131 and the heat transfer tubes 33 are alternately arranged in the Y direction.

  Further, with respect to both the air flow direction (X direction) and the longitudinal direction (Y direction) of the fin 31, the position of each louver 111, 121, 131 formed on the arbitrary fin 31 and adjacent to the arbitrary fin 31. The position of each louver 111, 121, 131 formed in another matching fin 31 coincides. That is, the louvers 111, 121, and 131 of an arbitrary fin 31 and the louvers 111, 121, and 131 of another fin 31 adjacent thereto are in a translational symmetry relationship with respect to the Z direction. If it does in this way, it will become easy to prevent obstruction | occlusion of the flow path at the time of frost formation, and it will become easy to adhere frost to the fin 31 uniformly.

  The upstream end of the louver 111 located on the most upstream side in the air flow direction is located upstream of the upstream end of the heat transfer tube 33. In this way, since the air guided to the heat exchanger 100 first comes into contact with the louver 111, a high leading edge effect can be obtained at the upstream end of the louver 111. Further, both end portions 112 and 122 of the louvers 111 and 121 are gently inclined toward the heat transfer tube 33. By such both end portions 112 and 122, air can be guided toward the side portion of the collar 11, which is one of the portions having the best heat transfer performance.

As shown in FIG. 2, in this embodiment, three louvers 111, 121, 131 are formed along the air flow direction. The lateral width W ₁ of the louver 111 and the louver 131 is larger than the lateral width W ₂ of the louver 121 and is the maximum lateral width that can form the collar 11. Note that “horizontal width of the louver” means the length of the louver in the Y direction. On the other hand, as shown in FIG. 3, the lengths T ₁ , T ₂ , T ₃ of the louvers 111, 121, 131 in the X direction are the same for all the louvers 111, 121, 131, for example, 1.8P ≦ T ₁ It is determined to satisfy the relationship of (, T ₂ , T ₃ ) ≦ 2.2P. In this way, air can flow smoothly and pressure loss can be prevented from rising excessively. Of course, the lengths T ₁ , T ₂ , T _{3 of the} louvers 111, 121, 131 may be different from each other. For example, the lengths T ₁ and T _{3 of} the louvers 111 and 113 may be equal to each other and larger than the length T _{2 of the} louvers 112. The “length of the louver in the X direction” means the length from the upstream end of the ventilation gaps 113, 123, 133 to the downstream end of the louvers 111, 121, 131.

  In the present embodiment, the inclination angle of the louvers 111, 121, 131 with respect to a plane (XY plane) parallel to the plurality of fins 31 is set to 30 °. As is apparent from the results of computer simulation described later, the heat exchange efficiency can be optimized by setting the inclination angle of the louvers 111, 121, 131 to 30 °. Note that “the inclination angle is 30 °” does not necessarily mean that the inclination angle completely coincides with 30 °. For example, if it is within a range of 30 ° ± 2 °, the “inclination angle is 30 °”.

  As shown in FIG. 3, the three louvers 111, 121, 131 are cut so that the louver 111 located on the most upstream side and the louver 131 located on the most downstream side face the same side in the Z direction. It has been awakened. The louver 121 between the two louvers 111 and 131 is cut and raised so as to face the opposite direction with respect to the Z direction. In other words, two louvers (louver 111 and louver 121, louver 121 and louver 131) that are adjacent to each other with respect to the air flow direction, are a first louver formed to guide air to the first side in the Z direction; And a second louver formed to guide air to the second side in the Z direction. In this way, since the air flow path meanders in the Z direction, the development of the boundary layer can be effectively prevented, and the heat transfer coefficient on the surface of the fin is increased. However, as shown in FIG. 4, the louvers 111, 121, 131 may be cut and raised in the same direction. From the viewpoint of suppressing an increase in pressure loss, the embodiment of FIG. 4 is also suitable.

  Note that the number of louvers to be formed along the air flow direction is not limited to three as long as the rigidity of the fins 31 can be sufficiently maintained. As long as a plurality of louvers are provided, the effect of meandering the flow path can be obtained.

  Moreover, as shown in FIG. 1, both the fin 31 which comprises the front row | line | column part 3 and the fin 31 which comprises the back row | line | column part 5 may have louvers 111, 121, 131, or either Only may have louvers 111, 121, 131. In the latter case, for example, a conventional corrugated fin may be used as the fin not having the louvers 111, 121, and 131. Corrugated fins can be used as the fins constituting the front row portion 3 where frost formation is more likely to occur, and the louver fins 31 of the present embodiment can be used as the fins constituting the rear row portion 5.

  Next, the operation of this embodiment will be described. FIG. 5 is an explanatory diagram relating to the air flow during drying as seen from the viewpoint of FIG. The air that flows in from the left of the drawing reaches the louver 111, and at the tip of the louver 111, passes through the ventilation gap 113 and branches into a flow 511 that flows above the louver 111 in the drawing and a flow 512 that flows below the louver 111 in the drawing. At this time, since the temperature boundary layer is also divided, the heat transfer coefficient is improved by the leading edge effect. Thereafter, also in the louver 121, the air flow is branched into the flow 522 flowing downward and the flow 521 flowing upward, and the heat transfer coefficient is improved. Further, in the louver 131, the heat transfer coefficient is similarly improved.

  Moreover, FIG. 6 is explanatory drawing regarding the air flow at the time of frost formation. Frosting occurs intensively at a portion where the amount of heat exchange is large, that is, at the tip portions of the louvers 111, 121, and 131. Therefore, when the amount of frost formation is large, the ventilation gaps 113, 123, 133 are closed by frost as shown in FIG. At this time, since the leading edge portion disappears, the heat transfer rate is lowered, but the air flow path is meandering up and down like a conventional corrugated fin, and the rate of reduction can be kept small. Further, the disappearance of the leading edge portion does not concentrate the heat exchange amount in one place, and relatively uniform heat exchange is performed over the entire region, so that frost begins to adhere to the fins 31 evenly. As a result, blockage of the air flow path due to frost formation can be delayed. When the ventilation gaps 113 to 133 are not blocked by frost, the advantage of the louver fin can be enjoyed. On the other hand, even if the ventilation gaps 113, 123, 133 are blocked by frost, the advantage of the corrugated fin can be enjoyed.

  On the other hand, FIG. 8 is sectional drawing of the conventional slit fin heat exchanger, and explanatory drawing regarding the air flow at the time of frost formation. As shown in FIG. 8, since the air flow is branched at the tip of the slit 811, the heat transfer rate is high for the reasons described above, and heat exchange is easily performed. Therefore, frost formation is concentrated on the tip of the slit 811. Even after the amount of frost formation increases to some extent, the air is divided and flows at the tip of the slit 811. Therefore, the heat transfer rate does not decrease at the tip of the slit 811 after frost formation, and frost formation further grows. The grown frost closes the base material 812 of the slit 811 (part corresponding to the “flat part” in the present embodiment) and the base material 813 of the adjacent fin, thereby closing the air flow path. This significantly increases the air flow resistance and prevents efficient heat exchange. As described with reference to FIG. 9, the conventional louver fin has the same problem.

  In contrast, in the present embodiment, the blockage of the air flow path can be significantly delayed, and efficient heat exchange can be continued for a long time even during frost formation.

  Regarding the heat exchanger having the fins 31 shown in FIG. 2 and FIG. 3, changes in heat exchange amount and air pressure loss when the louvers 111, 121, 131 are cut and raised with respect to the air inflow direction (X direction). Was investigated by computer simulation. For the computer simulation, “Fluent” manufactured by Fluent Asia Pacific was used. The calculation was performed under conditions of an inflowing air wind speed of 0.5 to 1.5 meters / second, an air temperature of 16 ° C, and a refrigerant temperature of 5.3 ° C. The results are shown in FIG.

  The horizontal axis of FIG. 7 represents the inclination angle (cutting and raising angle) of the louvers 111, 121, and 131. The vertical axis in FIG. 7 represents the heat exchange amount and air pressure loss. As shown in FIG. 7, the amount of heat exchange increased as the cut and raised angle increased. The amount of heat exchange reached its maximum when the cut-and-raised angle was about 30 °, and then decreased. On the other hand, the air pressure loss increased monotonically with the increase in the cut and raised angle. Considering the balance between the heat exchange amount and the air pressure loss, the cut-and-raised angle of about 30 ° at which the heat exchange amount is maximized is the best configuration.

  The heat exchanger according to the present invention has excellent heat exchange performance, and is particularly useful as a heat exchanger for heat pump air conditioners and water heaters that use air as a heat source, assuming use in cold regions.

1 is an external perspective view of a heat exchanger according to an embodiment of the present invention. The partial top view of the fin of the heat exchanger shown in FIG. A-A 'sectional view of FIG. FIG. 2 is a sectional view taken along the line A-A ′ of FIG. The figure explaining the air flow at the time of non-frosting of the cross section shown in FIG. The figure explaining the air flow at the time of frost formation of the cross section shown in FIG. A diagram showing the relationship between the louver raising angle with respect to the air inflow direction, heat exchange amount and air pressure loss The figure explaining the air flow at the time of frost formation of the conventional slit fin Cross section of conventional louver fin Sectional drawing at the time of frost formation of the louver fin shown in FIG.

Explanation of symbols

31 Fin 33 Heat transfer tube 35 Flat part 100 Heat exchanger 111, 121, 131 Louver (cut and raised)
112, 122, 132 Both ends 113, 123, 133 of louver Ventilation gaps H ₁ , H ₂ , H ₃ louver height P Fin pitch

Claims (5)

A heat exchanger for exchanging heat between the first fluid and the second fluid,
A heat transfer tube for circulating the first fluid inside, and a plurality of fins arranged in parallel to each other so that the flow path of the second fluid is formed outside the heat transfer tube,
Each of the surfaces of the plurality of fins is provided with a cut and raised to promote heat exchange between the first fluid and the second fluid by changing the flow direction of the second fluid,
The cut and raised portion extends obliquely toward another fin adjacent to the fin having the cut and raised portion,
The heat exchanger, wherein the height of the cut and raised is equal to the interval between the pair of adjacent fins. A heat exchanger for exchanging heat between the first fluid and the second fluid,
A heat transfer tube for circulating the first fluid inside, and a plurality of fins arranged in parallel to each other so that the flow path of the second fluid is formed outside the heat transfer tube,
Each of the plurality of fins is provided with a cut and raised portion for promoting heat exchange between the first fluid and the second fluid by changing the flow direction of the second fluid. A flat portion that is not a portion,
The cut and raised is inclined with respect to the flat portion so as to extend obliquely toward another fin adjacent to the fin having the cut and raised,
Allowing the second fluid to flow from the flow path on the first side of the fin to the flow path on the second side of the fin adjacent to the upstream end of the cut and raised in the flow direction of the second fluid Gap is formed,
The heat exchanger, wherein a height from a surface of the flat portion to an upstream end of the cut and raised is equal to a distance between the pair of adjacent fins. When the direction perpendicular to both the flow direction of the second fluid and the arrangement direction of the plurality of fins is defined as the longitudinal direction of the fins,
With respect to both the flow direction of the second fluid and the longitudinal direction of the fin, the position of the cut and raised formed in any fin and the cut formed in another fin adjacent to the arbitrary fin. The heat exchanger according to claim 1 or 2, wherein the positions of the raised portions coincide with each other and the raised portions are in a translational symmetry relationship with respect to the arrangement direction of the plurality of fins. Each of the plurality of fins includes a plurality of the raised portions along the flow direction of the second fluid,
The two cut and raised adjacent to each other with respect to the flow direction of the second fluid are a first cut and raised formed to guide the second fluid to the first side with respect to the arrangement direction of the plurality of fins, The heat exchanger according to any one of claims 1 to 3, further comprising: a second cut and raised portion configured to guide two fluids to a second side in an arrangement direction of the plurality of fins.   The heat exchanger according to any one of claims 1 to 4, wherein an inclination angle of the cut and raised with respect to a plane parallel to the plurality of fins is 30 °.

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