JP2009145010A - Fin-less heat exchanger for air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve heat exchange performance while securing compactness without causing increase of pressure loss in comparison with a fin-and-tube heat exchanger in a fin-less heat exchanger for an air conditioner. <P>SOLUTION: The fin-less heat exchanger 10 is equipped with a plurality of flat tubes 1 having flat passage cross section, and header tanks 2 connected to both ends of the flat tubes 1. In each flat tube 1, a tube with a minor outer diameter A within a range of 0.31-1.50 mm is used. The flat tubes 1 are arranged such that the major diameter direction is substantially in parallel with a flow 4 of air, and the flat tubes 1 are arranged at equal intervals in one row in a direction crossing a direction of the flow 4 of air. With the pitch of the flat tubes 1 represented by B, the flat tubes 1 are installed such that when A is 0.31 mm, B/A is 2.5-5.6, A is 0.63, B/A is 2.5-3.1, A is 1.00, B/A is 1.9-2.1, A is 1.25, B/A is 1.8-1.9, and A is 1.40, B/A is 1.74. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a finless heat exchanger for an air conditioner, and is particularly suitable for a finless heat exchanger for an air conditioner in which a plurality of flat tubes are juxtaposed in a row.

  BACKGROUND ART A heat exchanger that circulates a refrigerant inside and exchanges heat with air by evaporating and condensing the refrigerant is widely used in various fields including an air conditioner and a refrigerator. Although it is a heat exchanger that plays an active role in various applications such as cooling of heat-generating equipment and heating to working fluid, improvement of heat exchange performance and compactness is always required in every field, and both of these are essential for the equipment itself. It goes without saying that it works preferentially.

  Currently, there is a fin-and-tube heat exchanger as one of typical heat exchangers. This fin-and-tube heat exchanger is manufactured by passing a plurality of tubes through a plurality of thin fins in a direction perpendicular to the fin surface and expanding the tubes. This fin-and-tube heat exchanger features heat exchange performance and compactness by flowing refrigerant into the tube and exchanging heat with air using fins with a large heat transfer area that is in close contact with the outer wall of the tube. Various attempts have been made to improve sex. For example, in order to increase the heat transfer area, the fins are thinned to increase the number of fins or slits are provided on the fin surface, and the inner wall of the pipe is also uneven to increase the heat transfer area. The tube has been improved.

  However, in order to pursue further improvements in heat exchange performance and compactness in the future, it will be difficult to expect great effects only by accumulating partial improvements within the category of fin-and-tube heat exchangers. It is coming.

  Against this background, many studies on new types of heat exchangers that replace conventional fin-and-tube heat exchangers have been conducted. Among them, a finless heat exchanger, which is a heat exchanger configured without using fins, has recently attracted attention by increasing the heat transfer area by closely arranging a large number of tubes. There are various types of finless heat exchangers, ranging from the orthodox type in which circular tubes are regularly arranged to the complex type in which tubes having a rectangular, elliptical, or streamlined cross-section are irregularly arranged. Forms have been devised.

  For example, in Japanese Patent Application Laid-Open No. 2002-115934 (Patent Document 1), an evaporator installed in a refrigeration vehicle is composed of a plurality of flat tubes and header tanks arranged at both ends thereof, and a cross section of the flat tube. The major axis direction is arranged in parallel along the air flow direction. Thereby, since the development of frost in the evaporator is limited to the back side of the flat tube that is not directly exposed to air, it is possible to prevent a reduction in refrigeration capacity due to the development of frost formation in the air passage.

JP 2002-115934 A

  When it is necessary to keep the interior of the vehicle at a low temperature while regularly opening and closing the door as in the above-described Patent Document 1, it is particularly important to prevent a reduction in refrigeration capacity due to the development of frost formation. However, when the evaporator for a refrigeration vehicle of Patent Document 1 is used as a finless heat exchanger for an air conditioner, in terms of heat exchange performance, there is a risk that a decrease in heat exchange performance due to the elimination of fins becomes very large. There is. For example, a fin-and-tube heat exchanger having a tube outer diameter of about 7 mm, a fin pitch of about 1 mm, and a wind speed of air sent by a fan of about 1 m / s, such as an indoor heat exchanger of a domestic air conditioner, When changing to a finless heat exchanger using flat tubes without changing the exchanger size and fan input, the tube short outer diameter, which is the short diameter of the tube outer diameter, is reduced to about 2-3 mm, and the arrangement pitch Even if it is made small, the heat transfer area is insufficient and the heat exchange performance may be greatly reduced. In addition, if the arrangement pitch is further reduced to increase the heat transfer area, there is a problem in that the pressure loss due to the arrangement pitch being too small is caused and the application to the air conditioner becomes difficult. .

  An object of the present invention is to provide finless heat exchange for an air conditioner capable of improving heat exchange performance while ensuring compactness without causing an increase in pressure loss as compared with a fin-and-tube heat exchanger. Is to provide a vessel.

  In order to achieve the above-described object, the present invention provides a plurality of flat tubes having a flat channel cross section through which a refrigerant flows, and both ends of the plurality of flat tubes connected to both the flat tubes to allow the refrigerant to flow in and out. In the finless heat exchanger for an air conditioner, which is provided in a flow of air sent by a blower device, each flat tube has a short tube outer diameter which is a short diameter of the tube outer diameter. The flat tubes are formed in a range of 0.31 to 1.40 mm, and the long diameter direction of each of the flat tubes is arranged substantially parallel to the air flow, and the flat tubes are disposed of the air. When the flat tubes are juxtaposed at equal intervals in a direction intersecting the flow direction, the short tube outer diameter is A, and the pitch of each flat tube is B, A is 0.31 mm and B When / A is 2.5 to 5.6 and A is 0.63 mm, B / A is 2.5. 3.1, when A is 1.00 mm, B / A is 1.9 to 2.1, when A is 1.25 mm, B / A is 1.8 to 1.9, and when A is 1.40 mm, B / A is B / A. Each said flat tube is installed so that it may become in the range of 1.74.

A more preferable specific configuration example of the present invention is as follows.
(1) Each said flat tube has the curved surface shape where the both-ends wall surface part of the major axis direction has a moderate curved surface shape, and the side wall surface part which connects these both wall surface parts has a substantially flat shape.
(2) The header tank is formed by closing both ends of a cylindrical tube, and each flat tube is formed in the same length by vertically cutting both ends in the longitudinal direction and inserted into the header tank. Connected to the header tank.
(3) The flat tube is composed of a circular tube group in which a plurality of circular tubes are continuously arranged.
(4) The flat tube is one in which corrugated fins are inserted and brazed.

  According to the finless heat exchanger for an air conditioner of the present invention, the heat exchange performance is improved while ensuring compactness without causing an increase in pressure loss as compared with the fin-and-tube heat exchanger. be able to.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. The same reference numerals in the drawings of the respective embodiments indicate the same or equivalent.

(First embodiment)
The finless heat exchanger for air conditioners of 1st Embodiment of this invention is demonstrated using FIG. 1A, FIG. 1B, FIG. 2A, and FIG. 2B.

  First, the configuration and basic functions of the finless heat exchanger 10 of the present embodiment will be described with reference to FIGS. 1A and 1B. FIG. 1A is a partial cross-sectional perspective view of the finless heat exchanger 10 of the present embodiment, and FIG. 1B is an enlarged view showing a part of the arrangement of the flat tubes 1 taken along line CC in FIG. 1A.

  The finless heat exchanger 10 is connected to a plurality of flat tubes 1 having a flat channel cross section through which a refrigerant flows, and both end portions 1a of these flat tubes 1, and a header that allows the refrigerant to flow into and out of these flat tubes 1. And a tank 2. The flow of the refrigerant is indicated by reference numeral 3 in FIG. 1A.

  The finless heat exchanger 10 is disposed in an air flow 4 sent by a blower device inside an indoor unit of an air conditioner. This air conditioner is a general home air conditioner composed of an indoor unit and an outdoor unit, and the speed of the air flow 4 is about 1 m / s (specifically, 0.9 to 1.1 m). / S range). And the finless heat exchanger 10 comprises a part of refrigeration cycle of an air conditioner.

  In the flat tube 1, both end wall surfaces 1 b in the major axis direction have a gently curved surface shape, and a side wall surface portion 1 c connecting these both end wall surfaces 1 b has a substantially flat shape. The flat tube 1 is used in a range where the short tube outer diameter A (see FIG. 1B), which is the short dimension of the tube outer diameter, is 0.31 to 1.50 mm.

  The plurality of flat tubes 1 are arranged such that the long diameter direction of each flat tube 1 is substantially parallel to the air flow 4 and each flat tube 1 is 1.4 to 5.6 times the short tube outer diameter A. They are juxtaposed in a row in a direction that intersects the direction of air flow 4 with a pitch B within the range (see FIG. 1B).

  The header tank 2 has a structure in which one end of a cylindrical tube is completely closed and the other end is closed with a circulation port. Specifically, one end of each header tank 2 is closed by welding a cap having no flow port, and the other end is closed by welding a cap having a flow port. Each flat tube 1 is formed in the same length by vertically cutting both ends in the longitudinal direction, and is inserted into the header tank 2 and connected to the header tank 2. According to such a structure, the finless heat exchanger 10 can be manufactured at low cost.

  The refrigerant 3 flowing through the refrigeration cycle first flows into the header tank 2 on the back side of the drawing, and is distributed from the header tank 2 to the plurality of flat tubes 1. The refrigerant flowing through each flat tube 1 is heat-exchanged with the air flowing outside the flat tube 1. Here, when the finless heat exchanger 10 is used as an evaporator, the refrigerant flowing through each flat tube 1 is evaporated by exchanging heat with the air flowing outside the flat tube 1, and the finless heat exchanger 10 is a condenser. When the refrigerant is used as the refrigerant, the refrigerant flowing through each flat tube 1 is condensed by exchanging heat with the air flowing outside the flat tube 1. The refrigerant 3 that has passed through the flat tube 1 flows into the header tank 2 on the near side of the drawing, and flows out through the circulation port at the end of the header tank 2.

  Next, the flat tubes 1 are juxtaposed in a row in a direction crossing the direction of the air flow 4 with a pitch B in the range of 1.4 to 5.6 times the short tube outer diameter A. The reason will be described with reference to FIGS. 2A and 2B. FIG. 2A is a diagram showing the relationship between the pitch / tube diameter and the heat exchange amount ratio in the finless heat exchanger having the structure shown in FIG. 1A as a result of thermal fluid analysis, and FIG. 2B is the finless heat exchanger having the structure shown in FIG. 1A. It is a figure showing the relationship between a pitch / pipe diameter and a pressure loss ratio with the result of a thermal fluid analysis. The heat exchange amount ratio in FIG. 2A and the pressure loss ratio in FIG. 2B are comparative values for a fin-and-tube heat exchanger under the same heat exchanger size and fan input conditions.

  In the finless heat exchanger 10 using the flat tube 1 installed in a limited space inside the air conditioner, the short outer diameter A of the flat tube 1 and the flow of air flowing from the outside of the flat tube 1 It was found by thermal fluid analysis that two elements consisting of an arrangement pitch B perpendicular to the direction of 4 are very important parameters that determine performance.

  That is, as apparent from FIG. 2A, when the tube short outer diameter A is 0.31 mm, B / A is 5.6 or less, and when the tube short outer diameter A is 0.63 mm, B / A is 3.1 or less. B / A is 2.1 or less when the outer diameter A is 1.00 mm, B / A is 1.9 or less when the short tube outer diameter A is 1.25 mm, and B / A is when the short tube outer diameter A is 1.40 mm. When the tube outer diameter A is 1.50 mm or less and the B / A is 1.65 or less, the heat exchange amount ratio is 1 or more. In addition, 0.31 mm of the short pipe outer diameter A is a lower limit value in consideration of productivity.

  2B, when the tube short outer diameter A is 0.31 mm, B / A is 2.5 or more, and when the tube short outer diameter A is 0.63 mm, B / A is 2.1 or more. When the outer diameter A is 1.00 mm, B / A is 1.9 or more. When the tube short outer diameter A is 1.25 mm, B / A is 1.8 or more. When the tube outer diameter A is 1.40 mm, B / A is B / A. When the pipe outer diameter A is 1.50 mm or more and the B / A is in the range of 1.75 or more, the pressure loss ratio is 1 or more.

  Therefore, B / A is 2.5 to 5.6 when the tube short outer diameter A is 0.31 mm, and B / A is 2.1 to 3.1 when the tube short outer diameter A is 0.63 mm. When A is 1.00 mm, B / A is 1.9 to 2.1, when tube short outer diameter A is 1.25 mm, B / A is 1.8 to 1.9, and tube short outer diameter A is 1.40 mm. By installing each flat tube so that B / A is in the range of 1.74, it is possible to reduce the heat loss while ensuring compactness without causing an increase in pressure loss compared to the fin-and-tube heat exchanger. The exchange performance can be improved. In addition, when the short pipe outer diameter A is 1.50 mm, there is no range where B / A is 1 or more. As a result, the short pipe outer diameter A has an upper limit of 1.40 mm.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a sectional view showing a part of the arrangement of the flat tubes 1 of the finless heat exchanger for an air conditioner according to the second embodiment of the present invention.

  In the second embodiment, each flat tube 1 is composed of a circular tube group in which a plurality of circular tubes 5 are continuously arranged, but other configurations are the same as those of the first embodiment. In the flat tube 1 as well, it is possible to obtain the same heat exchange amount and pressure loss effect by setting the dimension ranges of the tube short outer diameter A and the arrangement pitch B in the same manner as in the first embodiment. It was confirmed by. According to this 2nd Embodiment, the performance improvement accompanying the increase in the heat-transfer area with respect to the refrigerant | coolant which flows through the inside of a pipe | tube, and the improvement of a pressure resistance can be anticipated further.

  In addition, you may comprise each flat tube 1 in the flat tube group which has arrange | positioned several flat tubes continuously. In this case, as compared with the second embodiment, the performance improvement and the pressure resistance improvement accompanying the increase in the heat transfer area are suppressed, but the manufacture becomes easy.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a sectional view showing a part of the arrangement of the flat tubes 1 of the finless heat exchanger for an air conditioner according to the third embodiment of the present invention.

  In the third embodiment, corrugated fins 6 are inserted into each flat tube 1 and brazed, and other configurations are the same as those in the first embodiment. According to the third embodiment, compared with the case of only the flat tube 1 of the first embodiment, an improvement in pressure resistance can be expected, and compared to the case of the flat tube 1 made of the circular tube group of the second embodiment. Thus, the manufacturing process can be reduced.

It is a partial cross section perspective view of the finless heat exchanger of a 1st embodiment of the present invention. It is an enlarged view which shows a part of arrangement | sequence of the flat tube cut | disconnected along CC line of FIG. 1A. It is a figure showing the relationship between the pitch / pipe diameter and heat exchange amount ratio in the finless heat exchanger of the structure shown to FIG. 1A by the result of a thermal fluid analysis. It is a figure showing the relationship between the pitch / tube diameter and the pressure loss ratio in the finless heat exchanger having the structure shown in FIG. It is sectional drawing which shows a part of arrangement | sequence of the flat tube of the finless heat exchanger for air conditioners of 2nd Embodiment of this invention. It is sectional drawing which shows a part of arrangement | sequence of the flat tube of the finless heat exchanger for air conditioners of 3rd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Flat tube, 2 ... Header tank, 3 ... Flow of refrigerant, 4 ... Flow of air, 5 ... Circular pipe, 6 ... Corrugated fin, 10 ... Finless heat exchanger, A ... Short pipe outer diameter (tube diameter), B: Arrangement pitch.

Claims (5)

A plurality of flat tubes having flat channel cross sections through which the refrigerant flows, and header tanks connected to both ends of the plurality of flat tubes to allow the refrigerant to flow into and out of the flat tubes; In a finless heat exchanger for an air conditioner arranged in a flow,
Each said flat tube is formed in the range whose tube short outside diameter which is the short axis size of the tube outside diameter is 0.31-1.40 mm,
The plurality of flat tubes are arranged such that the major axis direction of each flat tube is substantially parallel to the air flow, and the flat tubes are arranged in a row in a direction intersecting the air flow direction. Juxtaposed at equal intervals,
When each of the flat tubes has a short tube outer diameter A and the pitch of each flat tube is B, B / A is 2.5 to 5.6 when A is 0.31 mm, and B / A when A is 0.63 mm. When A is 2.5 to 3.1, A is 1.00 mm, B / A is 1.9 to 2.1, and when A is 1.25 mm, B / A is 1.8 to 1.9, and A is 1. The finless heat exchanger for an air conditioner, wherein each of the flat tubes is installed so that B / A is within a range of 1.74 at 40 mm.   2. Each flat tube according to claim 1, wherein both end wall surfaces in the major axis direction have a gently curved shape, and side wall surfaces connecting these both end wall surfaces have a substantially flat shape. Finless heat exchanger for air conditioner.   2. The header tank according to claim 1, wherein both ends of a cylindrical tube are closed, and each flat tube is formed to have the same length by vertically cutting both ends in the longitudinal direction. A finless heat exchanger for an air conditioner, which is inserted into the header tank and connected to the header tank.   The finless heat exchanger for an air conditioner according to claim 1, wherein the flat tube is formed of a circular tube group in which a plurality of circular tubes are continuously arranged.   2. The finless heat exchanger for an air conditioner according to claim 1, wherein the flat tube is one in which a corrugated fin is inserted and brazed.

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