JP2010025490A - Heat exchanger and air conditioner using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To smoothly discharge defrost water and dew condensation water by improving the shape of corrugated fins in a parallel flow type heat exchanger. <P>SOLUTION: This heat exchanger 1 includes: an upper header pipe 2 and a lower header pipe 3 disposed in parallel with each other at intervals; a plurality of flat tubes 4 disposed between the upper header pipe 2 and the lower header pipe 3 at prescribed pitches to communicate refrigerant passages 5 formed inside thereof to the inside of the upper header pipe 2 and the lower header pipe 3; and the corrugated fins 6 respectively disposed between the flat tubes 4. The corrugated fins 6 are bent at a right angle at corners of folds to form ventilation spaces 10 having the rectangular frontal shape. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a parallel flow type heat exchanger and an air conditioner using the same.

  A parallel arrangement in which a plurality of flat tubes are arranged between a plurality of (for example, two) header pipes so that a refrigerant passage inside the flat tubes communicates with the header pipe, and fins such as corrugated fins are arranged between the flat tubes. Flow type heat exchangers are widely used in outdoor units of car air conditioners and air conditioners for buildings.

  An example of a conventional parallel flow heat exchanger is shown in FIG. In the heat exchanger 1, two header pipes, an upper header pipe 2 and a lower header pipe 3, which are horizontal, are arranged in parallel at a predetermined interval as a plurality of header pipes. In FIG. 5, the upper side of the paper is the upper side in the vertical direction, and the lower side of the paper is the lower side in the vertical direction, and a plurality of flat tubes 4 are vertically arranged between the upper header pipe 2 and the lower header pipe 3 with a predetermined pitch ( (Tube pitch). The flat tube 4 is an elongated molded product obtained by extruding a metal having good heat conductivity such as aluminum, and a refrigerant passage 5 through which a refrigerant flows is formed inside. The upper header pipe 2 and the lower header pipe 3 are also made of a metal having good heat conduction, and the upper header pipe 2, the lower header pipe 3 and the flat tube 4 are fixed by brazing or welding.

  Since the flat tube 4 is disposed so that the extrusion molding direction is vertical, the refrigerant flow direction of the refrigerant passage 5 is also vertical. A plurality of refrigerant passages 5 having the same cross-sectional shape and cross-sectional area are arranged in the depth direction of FIG. 5, and thus the flat tube 4 has a harmonica-like cross section. Each refrigerant passage 5 communicates with the inside of the upper header pipe 2 and the lower header pipe 3.

  Between the flat tubes 4, corrugated fins 6 made of a metal having good heat conduction are arranged. The corrugated fin 6 has a saddle shape shown in FIG. 6 and a corrugated fin 6 shown in FIG. The corrugated fin 6 shown in FIG. 6 has a sawtooth shape having a sawtooth shape in which isosceles triangles whose apexes are directed horizontally and whose apex angles are acute are stacked with the apexes oriented alternately. The corrugated fin 6 shown in FIG. 7 has a semi-circular top portion. The flat tube 4 and the corrugated fin 6 are fixed by welding.

  Since a large number of flat tubes 4 are provided between the upper header pipe 2 and the lower header pipe 3, and the corrugated fins 6 are provided between the flat tubes 4, the heat dissipation (heat absorption) area of the heat exchanger 1 is large, and the efficiency Heat exchange can be performed. A refrigerant inlet 7 is provided at one end of the lower header pipe 3, and a refrigerant outlet 8 is provided at one end of the upper header pipe 2 at a position diagonal to the refrigerant inlet 7.

  When the parallel flow type heat exchanger 1 is used as an evaporator, a low-temperature refrigerant flows through the refrigerant passage 5, and the surface temperatures of the flat tubes 4 and the corrugated fins 6 are lowered. Thereby, the phenomenon (frosting phenomenon) that the water | moisture content in air adheres as a frost on the surface of the flat tube 4 or the corrugated fin 6 occurs. When frost formation occurs, the transfer of cold heat from the flat tube 4 or the corrugated fin 6 to the air is deteriorated, and the interval between the corrugated fins 6 is narrowed to make it difficult for the air to flow, so the heat exchange efficiency decreases. For this reason, the defrosting operation which reverses the roles of the evaporator and the condenser is sometimes performed to melt the frost.

  If the frost-melted water, that is, defrosted water remains attached to the flat tubes 4 and the corrugated fins 6, it will freeze when returning from the defrosting operation to the normal operation, thereby reducing the heat exchange efficiency. . Also, repeated defrosting may cause ice to grow and destroy the heat exchanger. Therefore, it is necessary to drain defrost water promptly.

  Further, in the indoor unit of the air conditioner, condensation occurs in the heat exchanger due to heat exchange with room air during the cooling operation. In the outdoor unit of the air conditioner, condensation occurs in the heat exchanger due to heat exchange with outdoor air during heating operation. Condensed water also reduces the heat exchange performance by narrowing the cross-sectional area of the air flow passage, so it must be drained quickly.

In order to quickly drain defrost water and dew condensation water, in the parallel flow type heat exchanger described in Patent Document 1, corrugated fin corrugated trough lines and ridge lines are inclined in the heat exchanger depth direction to remove defrost water. The water flows along the inclined fin surface to the lower end surface of the fin and flows down along the flat tube.
JP 2004-177040 A

  When defrosting is performed with a parallel flow heat exchanger, a bridge phenomenon (water film is stretched) due to the surface tension of water becomes a problem. When a bridging phenomenon occurs between corrugated fins, even if water hangs down to the end of the corrugated fin, only a film is stretched there and no dripping occurs. This is true for both defrosted water and condensed water.

  In the corrugated fin 6 shown in FIG. 6, a bridging phenomenon is likely to occur starting from the acute angle portion 9a of the heel. In the corrugated fin 6 shown in FIG. 7, a bridging phenomenon is likely to occur starting from a corner portion 9b that is tapered outside the semicircular top portion.

  The present invention has been made in view of the above points, and an object of the present invention is to allow the defrost water and condensed water to be smoothly drained by improving the shape of the corrugated fin in the parallel flow type heat exchanger. And

  In order to achieve the above object, the present invention provides a plurality of header pipes arranged in parallel at intervals, and a plurality of refrigerant pipes arranged at a predetermined pitch between the plurality of header pipes and provided inside. In the heat exchanger comprising a flat tube communicated with the inside of the header pipe, and a corrugated fin disposed between the flat tubes, the corrugated fin is bent at a right angle and has a rectangular front shape. It features a ventilation space.

  According to this configuration, the sharp or sunk corners where the water film tends to be stretched are eliminated from the corrugated fin ridges, and the bridge phenomenon is unlikely to occur. For this reason, the defrost water flows down smoothly, and when returning from the defrost operation to the normal operation, there is little possibility that water droplets remaining without being drained freeze and impair the heat exchange performance. Condensed water also flows down in the same manner as defrosted water, so that the cross-sectional area of the air flow passage is narrowed by the water, and there is no need to worry about reducing the heat exchange performance.

In the heat exchanger configured as described above, the ventilation space has a rectangular shape with a front shape and a short side of 5 mm.
As described above, the long side is preferably set to 10 mm or more.

  In the heat exchanger configured as described above, the corrugated fin is preferably made of aluminum.

  In the heat exchanger having the above configuration, the corrugated fin has a sawtooth shape, and a corrugated fin having a right angle is obtained by pressing the material between two parallel flat plates. Is preferred.

  With such a configuration, a desired ridge shape can be formed efficiently.

  Moreover, the present invention is an air conditioner that uses the heat exchanger unit.

  According to this configuration, it is possible to obtain an air conditioner in which the heat exchange performance is hardly deteriorated even when defrosted water or condensed water is generated.

  According to the present invention, the sharp or splayed corners where the water film tends to be stretched are eliminated from the corrugated fin ridges, so that the bridging phenomenon is less likely to occur. There is no need to worry about a decline in heat exchange performance.

  Hereinafter, an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a partial front view of the heat exchanger. Elements functionally common to the heat exchanger having the conventional structure shown in FIG. 5 are denoted by the same reference numerals as those used in FIG.

  In the corrugated fin 6 shown in FIG. 1, the corners of the ridges are bent at a right angle. For this reason, a front-shaped rectangular ventilation space 10 is formed between the corrugated fins 6.

  According to the above configuration, the sharp or sunk corners where the water film tends to be stretched are eliminated from the corrugated fin 6 ridges, and the bridge phenomenon is unlikely to occur. For this reason, the defrost water flows down smoothly, and when returning from the defrost operation to the normal operation, there is little possibility that water droplets remaining without being drained freeze and impair the heat exchange performance. Condensed water also flows down in the same manner as defrosted water, so that the cross-sectional area of the air flow passage is narrowed by the water, and there is no need to worry about reducing the heat exchange performance.

Both the flat tube 4 and the corrugated fin 6 are made of aluminum. Then, the rectangular shape of the front shape of the ventilation space 10 formed between the corrugated fins 6 is set such that the short side is 5 mm or more and the long side is 10 mm or more. By setting the dimensions in this way,
Defrost water and condensed water flow smoothly without causing a bridging phenomenon. 10mm short side
The above is even better. The tube pitch of the flat tubes 4 and the fin pitch of the corrugated fins 6 are set so that the dimensions of the ventilation space 10 are as described above.

The above dimension setting is based on the drainage test result shown in FIG. In the test, a frame-shaped test piece in which the front shape of the internal space (ventilation space) was rectangular was created using an aluminum plate. A plurality of types of test pieces were prepared by changing the X-direction dimension and the Y-direction dimension of the rectangle in various ways. The test piece was submerged in water 5 mm from the lower end so that the axis of the internal space was vertical, and then slowly pulled up. Ten seconds after the test piece was separated from the water, it was examined whether or not a bridging phenomenon occurred in the internal space. Here, it was determined that “there is a bridging phenomenon” when water forms a film over 10% of the cross-sectional area of the internal space. This test was repeated three times for each test piece, and if no bridging phenomenon occurred in all three times, the test was indicated by “◯”. When the bridging phenomenon occurs once or twice in three times, it is indicated by “Δ” in the table. When the bridging phenomenon occurred three times, it was indicated by “x” in the table.

From the above test results, the rectangular shape, which is the front shape of the internal space (ventilated space), has a short side of 5 mm.
As described above, it can be seen that when the long side is 10 mm or more, the bridging phenomenon is less likely to occur. If the short side is 10 mm or more, the bridging phenomenon will not occur.

  The corrugated fin 6 in which the corners of the ridges are bent at right angles can be formed as follows.

  First, as a first method, there is a method in which an aluminum plate is pressed to make a ridge having a rectangular front shape.

  As a second method, there is a method shown in FIG. Here, the material 11 in which the hook shape is serrated like the one shown in FIG. 6 is prepared. When the material 11 is sandwiched between two parallel flat plates 12 and pressed, a corrugated fin 6 having a hook shape with right-angled corners can be obtained as seen on the right side of the figure. If such a manufacturing method is employ | adopted, the corrugated fin 6 of a desired shape can be manufactured efficiently.

  FIG. 4 shows a modification of FIG. The material 11 in FIG. 4 has a bowl shape in which acute angles and obtuse angles appear alternately. If the material 11 is also pressed between two parallel flat plates 12, as shown on the right side of the figure, the corrugated fin 6 has a hook shape with right angles.

  The heat exchanger 1 according to the present invention can be used, for example, in an air conditioner. In that case, it is preferable to install the heat exchanger 1 in the air conditioner as follows. That is, the longitudinal direction of the upper header pipe and the lower header pipe is horizontal, and the flat tube 4 is installed so as to be inclined when viewed from the side. The flat tube 4 is inclined so that the windward side faces upward and the leeward side faces downward. If installed in this way, the ventilation space of the corrugated fins 6 is higher on the windward side and lower on the leeward side, so that defrost water and dew condensation water generated on the surface of the corrugated fins 6 is caused by gravity on the leeward side end. It flows to the department. The water reaching the leeward end of the corrugated fin 6 flows or falls to the lower part of the heat exchanger 1 without causing a bridge phenomenon.

  The inclination of the flat tube 4 can be further extreme, and the flat tube 4 can be installed so as to be horizontal when viewed from the side. The defrost water and dew condensation water generated on the surface of the corrugated fins 6 flows to the leeward side end of the corrugated fins 6 due to gravity and dripped from there.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  The present invention is widely applicable to parallel flow heat exchangers.

The partial front view of the heat exchanger which concerns on embodiment of invention Table showing corrugated fin drainage test results Illustration of corrugated fin formation method Explanatory drawing of the modification of a corrugated fin formation method Vertical sectional view showing the schematic structure of a conventional parallel flow heat exchanger Partial front view of a parallel flow heat exchanger showing a conventional corrugated fin shape Partial front view of parallel flow type heat exchanger showing another example of conventional corrugated fin shape

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat exchanger 2 Upper header pipe 3 Lower header pipe 4 Flat tube 5 Refrigerant passage 6 Corrugated fin 7 Refrigerant inflow port 8 Refrigerant outflow port 10 Ventilation space 11 Material 12 Flat plate

Claims (5)

A plurality of header pipes arranged in parallel at intervals, and a plurality of flat tubes arranged at a predetermined pitch between the plurality of header pipes and having refrigerant passages provided therein communicated with the inside of the header pipe And a heat exchanger comprising corrugated fins disposed between the flat tubes,
The corrugated fin is a heat exchanger characterized in that a corner of a ridge is bent at a right angle to form a front-shaped rectangular ventilation space. 2. The heat exchanger according to claim 1, wherein the ventilation space has a rectangular shape with a front side set to have a short side of 5 mm or more and a long side of 10 mm or more.   The heat exchanger according to claim 1 or 2, wherein the corrugated fin is made of aluminum.   2. The corrugated fin according to claim 1, wherein the corrugated fin has a sawtooth shape, and a corrugated fin having a right angle is obtained by pressing the material between two parallel flat plates. The described heat exchanger.   An air conditioner using the heat exchanger according to any one of claims 1 to 4.

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