JPH058354U - Heat exchanger - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a heat exchanger whose performance does not deteriorate excessively during frost formation. [Structure] A pair of parallel headers made of large-diameter tubes, and an outer diameter of 4 m, which is arranged at regular intervals and is joined to the headers so that they communicate with each other.
A small-diameter tube group consisting of tubes of m or less was provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

  The present invention relates to an outdoor heat exchanger applied to an air-cooled heat pump.

[0002]

[Prior art]

  FIG. 6 is a refrigerant circuit diagram of a general heat pump air conditioner. In the figure, 1 is outdoor A heat exchanger, 2 is an indoor heat exchanger, 3 is a compressor, 4 is a four-way valve, and 5 is a throttle.

[0003]   FIG. 7 is a partially enlarged view of the conventional outdoor heat exchanger 1. The same figure (a) is a top view and the same figure. 7B is a cross-sectional view taken along line CC of FIG. 7A, and FIG. 8 is DD of FIG. 7B during frost formation. FIG. The heat exchanger connects the tubes 6 and 6 with a U-shaped tube 6a, The tube 7 is arranged orthogonal to the tube 6. The heat pump air conditioner It absorbs heat from the outside through the space between the cores 7 and dissipates heat in the indoor heat exchanger 2 for heating. However, when the outside air temperature is low, frost 8 adheres to the surface of the fin 7 as shown in FIG. Lengthen. Therefore, the thermal resistance of the frost 8 increases and the heat transfer property decreases, so the characteristic diagram of FIG. As indicated by the dotted line in, there is a drawback in that the heat exchange capacity is reduced.

[0004]

[Problems to be solved by the device]

  The present invention solves the above-mentioned drawbacks of the prior art, and even if the frost 8 adheres and grows, the heat exchange ability is improved. The purpose of the present invention is to provide a heat exchanger in which the reduction in power does not occur much.

[0005]

[Means for Solving the Problems]

  The present invention solves the above problems and relates to a heat exchanger having the following features. It is something. (1) Between a pair of parallel headers made of large diameter tubes and the same pair of headers 4m outside diameter connected to the header at regular intervals so that they communicate with each other A small-diameter tube group consisting of tubes of m or less was provided. (2) In the heat exchanger according to the above item (1), each small-diameter tube in the small-diameter tube group is provided at one location. Bending as described above to form a plurality of rows of small-diameter tube groups. (3) In the heat exchanger according to the above item (1), each header of the pair of headers is 1 Forming multiple rows of small-diameter tubes by bending at multiple points.

[0006]

[Action]

  In the heat exchanger of the present invention, heat exchange is performed in the small diameter tube group. For small diameter tubes In addition, when frost adheres and grows, the heat transfer area increases, so the heat transfer performance is reduced. It is erased and prevented. According to the experimental results (Fig. 9 described later), the outer diameter of the thin tube of 4 mm was frosted. At times, it is the limit to maintain the performance before frost formation. In practice, use a pipe of 4 mm or less. Need to be present.

[0007]

【Example】

  FIG. 1 (a) is a front view of a first embodiment of a heat exchanger of the present invention, and FIG. 1 (b) is the same view (a). 3 is a sectional view taken along line AA of FIG. In the figure, 9 is an upper header made of a circular pipe, and 10 is a circular pipe. The lower header 11 is composed of a straight thin tube which connects the upper and lower headers. Book The heat exchanger is made of a long material, but in making it into a product, Is cut out to a required size L and used. For the small diameter pipe 11, a pipe with an outer diameter of 4 mm or less is used. Can be

[0008]   FIG. 2 is a perspective view of a second embodiment of the present invention. This example shows the above element with the necessary dimensions cut out. In a small diameter tube group of material, it is configured as a three-row heat exchanger by bending it in two places. 11a is the bent thin tube.

[0009]   FIG. 3 is a perspective view of a third embodiment of the present invention, shown in FIG. 1 cut out to a certain length. It is configured as a three-row heat exchanger by stacking three material heat exchangers.

[0010]   FIG. 4 is a perspective view of a fourth embodiment of the present invention, showing the upper and lower parts of the material heat exchanger. Badders each bent at two places and meandered to form a three-row heat exchanger And 9a and 10a are bent headers at the upper and lower portions, respectively.

FIG. 5 is a cross-sectional view in a state where the frost 8 is attached around the small diameter tube 11. The heat transfer amount Q of the heat exchanger is expressed by the following equation. Q = k ・ A ・ △ T ……………………………… (1) where k: heat transfer rate A: heat transfer area ΔT: temperature difference heat transfer area Q becomes large. The heat transfer area A _O per unit length of the thin tube before frost formation is A _O = πd _O , and the heat transfer area A _f when frost having a thickness t _f is attached is A _f = π (d _O + 2t _f ). It increased ratio of heat transfer area is _{therefore, A f / A O = (} d o + 2t f) / d o ............ (2) Now, for example, d _O = 2 mm, if t _f = 1 mm, the heat transfer area The increase ratio of is A _f / A _O = 2. In the case of the conventionally used flat plate, the heat transfer area does not change before and after frost formation, but in the case of using a small diameter tube, it increases after frost formation. Therefore, the performance at the time of frosting is improved as compared with the conventional flat plate.

[0012]   FIG. 9 is a performance comparison diagram of the present invention and a conventional example (flat plate) based on experiments. Heat exchange capacity In the heat exchanger of the present invention, the conventional type decreases with the passage of frosting time. Shows that the performance improves with the passage of frosting time, or that the performance deterioration is minimal. It The outer diameter of the thin tube is 4 mm, which is the limit for maintaining the performance before frost formation.

[0013]

[Effect of device]

  The heat exchanger of the present invention includes a pair of parallel headers made of large-diameter tubes, and A pair of headers are placed at regular intervals so that they can communicate with each other and contact the headers. It is equipped with a small-diameter tube group consisting of combined tubes with an outer diameter of 4 mm or less. Each of the diameter pipes may be bent at one or more places to form a row of small diameter pipes, or a pair of heads Bend each header of one or more parts to form multiple rows of small diameter tubes. Therefore, it is possible to provide a heat exchanger that does not excessively deteriorate the performance when frost is formed. it can.

[Brief description of drawings]

FIG. 1A is a front view of a first embodiment of a heat exchanger of the present invention, and FIG. 1B is a sectional view taken along line AA of FIG.

FIG. 2 is a perspective view of a second embodiment of the heat exchanger of the present invention.

FIG. 3 is a perspective view of a third embodiment of the heat exchanger of the present invention.

FIG. 4 is a perspective view of a fourth embodiment of the heat exchanger of the present invention.

FIG. 5 is a cross-sectional view of a thin tube of the heat exchanger of the present invention during frost formation.

FIG. 6 is a refrigerant circuit diagram of a general heat pump air conditioner.

FIG. 7 is a partially enlarged view of a conventional outdoor heat exchanger.

FIG. 8 is a cross-sectional view taken along line DD of FIG. 7B when frost is formed.

FIG. 9 is a heat exchange capacity comparison diagram.

[Explanation of symbols]

1 outdoor heat exchanger 2 Indoor heat exchanger 3 compressor 4 four-way valve 5 aperture 6 tubes 6a U-shaped tube 7 fins 8 frost 9 Upper header 9a Upper bend header 10 Lower header 10a Lower bend header 11 small diameter tube 11a Small diameter bent pipe

Claims (3)

[Scope of utility model registration request] 1. A pair of parallel headers made of large-diameter tubes, and an outer diameter 4 joined to the headers arranged at regular intervals so as to communicate between the same pair of headers.
A heat exchanger comprising a small-diameter tube group composed of tubes of mm or less. 2. The heat exchanger according to claim 1, wherein each small diameter tube of the small diameter tube group is bent at one or more places to form a plurality of rows of small diameter tube groups. 3. The heat exchanger according to claim 1, wherein each of the pair of headers is bent at one or more places to form a plurality of rows of small-diameter tube groups.